GOLF CLUB HEAD

Description

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Japanese Patent Application No. 2024-128750 filed on Aug. 5, 2024. The entire contents of this Japanese Patent Application are hereby incorporated by reference.

BACKGROUND

Technical Field

The present disclosure relates to golf club heads.

Description of the Related Art

A golf club head is known that includes a face portion in which a fiber reinforced resin is used. JP 2013-236953A (US 2009/0163291A1) discloses a golf club head that includes a face plate having a lay-up of multiple, composite prepreg plies.

SUMMARY

It has been found that a new layered structure provides an improved face member. One of the objectives of the present disclosure is to provide a golf club head that includes a face member including a fiber reinforced resin and that exhibits excellent design flexibility regarding rebound properties.

In one aspect, a golf club head includes: a face member including a plurality of fiber reinforced resin layers; and a body member. The face member includes a quasi-isotropic layered portion in which at least some of the fiber reinforced resin layers are superposed on one another such that relative angles of fiber orientations of the respective fiber reinforced resin layers form a quasi-isotropic pattern. The face member further includes one or more configurations selected from a group consisting of the following (x), (y), and (z):

• • (x) a configuration that includes a distinct fiber-orientation layer containing fibers oriented at a predetermined fiber orientation angle that is different from fiber orientation angles of the fiber reinforced resin layers included in the quasi-isotropic layered portion;
  • (y) a configuration that includes a fiber-amount increasing layer that relatively increases the amount of fibers at a predetermined fiber orientation angle selected from the fiber orientation angles of the fiber reinforced resin layers included in the quasi-isotropic layered portion; and
  • (z) a configuration that includes a high elastic layer that has a relatively high fiber elastic modulus at a predetermined fiber orientation angle selected from the fiber orientation angles of the fiber reinforced resin layers included in the quasi-isotropic layered portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a golf club head according to a first embodiment;

FIG. 2 is a plan view of the golf club head according to the first embodiment;

FIG. 3 is a front view of the golf club head according to the first embodiment;

FIG. 4 is an exploded perspective view of the golf club head according to the first embodiment;

FIG. 5 is a cross-sectional view taken along line A-A in FIG. 2;

FIG. 6 is a front view of a body member according to the first embodiment;

FIG. 7 is a cross-sectional view taken along line A-A in FIG. 6;

FIG. 8A is an exploded view illustrating an example of the layered structure of the face member (body part), and FIG. 8B is an exploded view illustrating another example of the layered structure of the face member (body part);

FIG. 9 is an exploded view illustrating another example of the layered structure of the face member (body part), the example of FIG. 9 including a distinct fiber-orientation layer;

FIG. 10A and FIG. 10B are exploded views illustrating other examples of the layered structure of the face member (body part), the examples of FIG. 10A and FIG. 10B including their respective fiber-amount increasing layers;

FIG. 11A and FIG. 11B are exploded views illustrating other examples of the layered structure of the face member (body part), the examples of FIG. 11A and FIG. 11B including their respective high elastic layers;

FIG. 12 is a conceptual diagram illustrating an effect brought about by anisotropy;

FIG. 13 is a perspective view of a golf club head according to a second embodiment;

FIG. 14 is a plan view of the golf club head according to the second embodiment;

FIG. 15 is a front view of the golf club head according to the second embodiment;

FIG. 16 is an exploded perspective view of the golf club head according to the second embodiment;

FIG. 17 is a cross-sectional view taken along line A-A in FIG. 14;

FIG. 18 is a conceptual diagram for illustrating a reference state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present disclosure will be described in detail based on preferred embodiments with appropriate references to the accompanying drawings. The same or corresponding elements in the following embodiments are denoted by the same reference symbols. Repeated explanations are omitted as appropriate.

In the present disclosure, a reference state, a reference perpendicular plane, a toe-heel direction, a face-back direction, an up-down direction, a face center, and a face front view are defined as follows.

The reference state is defined as a state where a head is placed at a predetermined lie angle on a ground plane HP. As shown in FIG. 18, in the reference state, a shaft axis line Z lies in (is contained in) a plane VP that is perpendicular to the ground plane HP. The shaft axis line Z is defined as the center line of a shaft. The shaft axis line Z normally coincides with the center line of a hosel hole. The plane VP is referred to as the reference perpendicular plane. The predetermined lie angle is shown in product catalogs, for example.

A club is known that allows adjustment of its loft angle, lie angle, and face angle by, for example, changing the rotational position of a sleeve provided at the tip portion of the shaft. In such a club, the sleeve can be detachably fixed to the head with a fixing means, such as a screw. For this reason, in this club, the shaft is attachable to and detachable from the head. In a club having such an attachable and detachable mechanism, all adjustable items are set to their respective neutral positions when the club is in the reference state. The term “neutral” refers to the center of the adjustment range. All adjustable items can be set to their respective neutral positions by attaching a shaft, equipped with a sleeve that is not inclined relative to the shaft, to a head, and aligning the center line of the hosel hole with the shaft axis line.

In the reference state, a face angle is 0°. That is, in a planar view of a head as viewed from above, a line normal to its striking face at the face center is set to be perpendicular to the toe-heel direction. The definitions of the face center and the toe-heel direction are as explained below.

In the present disclosure, the toe-heel direction is defined as the direction of an intersection line NL between the reference perpendicular plane VP and the ground plane HP (see FIG. 18).

In the present disclosure, the face-back direction is defined as a direction that is perpendicular to the toe-heel direction and is parallel to the ground plane HP.

In the present disclosure, the up-down direction is defined as a direction that is perpendicular to the toe-heel direction and is perpendicular to the face-back direction. In other words, the up-down direction in the present disclosure is a direction perpendicular to the ground plane HP.

In the present disclosure, the face center is determined in the following manner. First, a point Pr is selected roughly at the center of a striking face in the up-down direction and the toe-heel direction. Next, a plane that passes through the point Pr, extends in the direction of a line normal to the striking face at the point Pr, and is parallel to the toe-heel direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Px of this intersection line is determined. Next, a plane that passes through the midpoint Px, extends in the direction of a line normal to the striking face at the midpoint Px, and is parallel to the up-down direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Py of this intersection line is determined. Next, a plane that passes through the midpoint Py, extends in the direction of a line normal to the striking face at the midpoint Py, and is parallel to the toe-heel direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Px of this intersection line is newly determined. Next, a plane that passes through this newly-determined midpoint Px, extends in the direction of a line normal to the striking face at this midpoint Px, and is parallel to the up-down direction is determined. An intersection line between this plane and the striking face is drawn, and a midpoint Py of this intersection line is newly determined. By repeating the above-described steps, points Px and Py are sequentially determined. In the course of repeating these steps, when the distance between a newly-determined midpoint Py and a midpoint Py determined in the immediately preceding step first becomes less than or equal to 0.5 mm, the newly-determined midpoint Py (the midpoint Py determined last) is defined as the face center.

In the present disclosure, the face front view refers to an orthogonal projection of a head obtained by projecting the head in a projecting direction that is a direction of a line normal to the striking face at the face center. Unless otherwise described, shapes, areas, dimensions and the like of respective portions/regions/parts of a face portion are determined in the face front view. The face front view is also simply referred to as a front view in the present disclosure.

FIG. 1 is a perspective view of a head 4 according to a first embodiment of the present disclosure. FIG. 2 is a plan view of the head 4 as viewed from a crown side. FIG. 3 is a front view of the head 4 as viewed from a face side. FIG. 4 is an exploded perspective view of the head 4. FIG. 5 is a cross-sectional view taken along line A-A in FIG. 2. FIG. 6 is a front view of a body member b1 of the head 4. FIG. 7 is a cross-sectional view taken along line A-A in FIG. 6. FIG. 3 is an example of the face front view.

As shown in FIG. 1, the head 4 includes a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 includes a striking face 10a. The striking face 10a constitutes the outer surface of the face portion 10. The striking face 10a is also simply referred to as a face or a face surface. The striking face 10a is a portion that comes into contact with a ball when the head 4 strikes the ball. The crown portion 12 includes an upper surface (crown surface) of the head 4. The sole portion 14 includes a lower surface (sole surface) of the head 4. The striking face 10a includes a face center Fc as defined above. The hosel portion 16 has a hosel hole (shaft receiving hole) 16a.

The head 4 has a hollow structure. The head 4 is designed as a driver (also known as a number one wood). The head 4 is a wood type head. The type of the head 4 is not limited. The head 4 may be a wood type head, a hybrid type head, an iron type head, or a putter type head. Examples of the wood type head include a driver head, a fairway wood head.

As shown in FIG. 4, from the viewpoint of constituent members, the head 4 includes a face member f1 and the body member b1. The face member f1 is fixed to the body member b1.

As shown in FIG. 4 and FIG. 5, the face member f1 includes a front surface f10, a rear surface f11, a side surface f12, and an outer peripheral edge f13. The front surface f10 is the outer surface of the face member f1. The front surface f10 constitutes the striking face 10a. In the present embodiment, the entirety of the front surface f10 is the striking face 10a. The rear surface f11 is the inner surface of the face member f1. The rear surface f11 faces a hollow interior 20 of the head 4, except for a portion supported by a support portion 18b (described later) (see FIG. 5). The side surface f12 extends between the front surface f10 and the rear surface f11. The outer peripheral edge f13 is formed by the intersection of the side surface f12 and the front surface f10.

A large portion of the face member f1 is not supported by the body member b1 (support portion 18b). Preferably, the ratio of the area of the portion of the face member f1 whose rear surface f11 faces an empty space (i.e., the hollow interior 20) to the total area of the face member f1 is greater than or equal to 60%. More preferably, the ratio of the area of the portion of the face member f1 whose rear surface f11 faces an empty space (i.e., the hollow interior 20) to the total area of the face member f1 is greater than or equal to 62%. Still more preferably, the ratio of the area of the portion of the face member f1 whose rear surface f11 faces an empty space (i.e., the hollow interior 20) to the total area of the face member f1 is greater than or equal to 64%. This ratio of the areas may be less than 100%, further may be less than or equal to 90%, and still further may be less than or equal to 80%. The area (total area) of the face member f1 is defined as the area of the striking face 10a formed by the face member f1. In the present embodiment, the area of the face member f1 is defined as the area of the front surface f10. When the striking face 10a includes score lines, the area is measured in a state where the score lines are filled to form a smooth striking face.

As shown in FIG. 6 and FIG. 7, the body member b1 includes an opening 18. The opening 18 forms a through hole that penetrates through the wall of the head 4 from the outer surface to the inner surface of the head 4. The opening 18 includes an opening edge 18a that defines the through hole, and the support portion 18b formed around the opening edge 18a. The opening 18 includes a contour edge 18c formed on the outer surface of the head 4. The shape of the contour edge 18c corresponds to the shape of the outer peripheral edge f13 of the face member f1. The opening 18 includes a stepped surface 18d. The stepped surface 18d extends from the outer edge of the support portion 18b to the contour edge 18c. The stepped surface 18d faces the side surface f12 of the face member f1 (see FIG. 5). The height of the stepped surface 18d corresponds to the wall thickness of the face member f1. The support portion 18b supports the peripheral part of the face member f1 from the back side.

The body member b1 includes at least a part of the crown portion 12. In the present embodiment, the body member b1 includes the entirety of the crown portion 12. The body member b1 includes at least a part of the sole portion 14. In the present embodiment, the body member b1 includes the entirety of the sole portion 14. The body member b1 includes at least a part of the hosel portion 16. In the present embodiment, the body member b1 includes the entirety of the hosel portion 16.

The body member b1 may include a part of the face portion 10. In the present embodiment, a large part of the face portion 10 is formed by the face member f1. The body member b1 may include a part of the striking face 10a. In the present embodiment, the entirety of the striking face 10a is formed by the face member f1.

The body member b1 may be integrally formed as a single-piece member. Alternatively, the body member b1 may be formed by joining a plurality of members to each other. The material of the body member b1 is not limited. Examples of the preferable material for the body member b1 include metals, fiber reinforced resins, and combinations thereof. Examples of the metals include titanium alloys, pure titanium, stainless steel, maraging steel, and soft iron. Examples of the fiber reinforced resins include carbon fiber reinforced resins. In the present embodiment, the body member b1 is integrally produced as a single-piece member by casting. In the present embodiment, the body member b1 is made of a titanium alloy.

The face member f1 is made of a fiber reinforced resin. As shown in an enlarged portion of FIG. 5, the face member f1 is formed by a plurality of fiber reinforced resin layers S superposed on one another. Each fiber reinforced resin layer S is formed from a prepreg (i.e., a prepreg sheet). In the prepreg, fibers are substantially oriented in one direction. Such a prepreg in which fibers are oriented substantially in one direction is also referred to as a UD prepreg. The term “UD” stands for unidirectional. Alternatively, a prepreg other than the UD prepreg may be used. For example, the prepreg may contain fibers oriented in multiple directions, which may be woven. The fibers are not limited to a specific type. Examples of the fibers include carbon fibers and glass fibers. From the viewpoint of strength, carbon fibers are preferably used. In the present embodiment, the fiber reinforced resin layers S are carbon fiber reinforced resin layers.

The fiber reinforced resin layers S are formed from respective prepreg sheets cut out to have the same shape as the face member f1. The prepreg sheets are superposed on one another and then pressurized and heated in a mold to form the face member f1.

A fiber orientation angle (i.e., the angle of orientation of the fibers) is predetermined for the fibers contained in each of the fiber reinforced resin layers S in the face member f1. To specify the fiber orientation angle, a fiber orientation angle θ is defined in the present disclosure. As shown in the face front view (FIG. 3), the toe-heel direction is designated as 0°, and the fiber orientation angle θ (positive θ) is defined as the angle measured clockwise from this 0° reference. The fiber extending direction of each fiber reinforced resin layer S can be indicated by the fiber orientation angle θ.

The face member f1 includes a quasi-isotropic layered portion in which the fiber reinforced resin layers S are superposed on one another such that the relative angles of fiber orientations of the respective fiber reinforced resin layers S form a quasi-isotropic pattern. The quasi-isotropic layered portion is constituted by at least some of the fiber reinforced resin layers S constituting the face member f1. In other words, the quasi-isotropic layered portion is constituted by either a subset of the fiber reinforced resin layers S constituting the face member f1, or all of the fiber reinforced resin layers S constituting the face member f1.

Table 1 below shows examples of quasi-isotropic patterns.

TABLE 1
Example of quasi-isotropi patients

		Angular
	Number of	interval
□	angles n	(degree)	Fiber extending direction(relative angle α (degree))

A	2	90.0	0.0	90.0	□	□	□	□	□	□	□
B	3	60.0	0.0	60.0	120.0	□	□	□	□	□	□
C	4	45.0	0.0	45.0	90.0	135.0	□	□	□	□	□
D	5	36.0	0.0	36.0	72.0	108.0	144.0	□	□	□	□
E	6	30.0	0.0	30.0	60.0	90.0	120.0	150.0	□	□	□
F	7	25.7	0.0	25.7	51.4	77.1	102.9	128.6	154.3	□	□
G	8	22.5	0.0	22.5	45.0	67.5	90.0	112.5	135.0	157.5	□
H	9	20.0	0.0	20.0	40.0	60.0	80.0	100.0	120.0	140.0	160.0
I	10	18.0	0.0	18.0	36.0	54.0	72.0	90.0	108.0	126.0	144.0
J	11	16.4	0.0	16.4	32.7	49.1	65.5	81.8	98.2	114.5	130.9
K	12	15.0	0.0	15.0	30.0	45.0	60.0	75.0	90.0	105.0	120.0
L	13	13.8	0.0	13.8	27.7	41.5	55.4	69.2	83.1	96.9	110.8
M	14	12.9	0.0	12.9	25.7	38.6	51.4	64.3	77.1	90.0	102.9
N	15	12.0	0.0	12.0	24.0	36.0	48.0	60.0	72.0	84.0	96.0
O	16	11.3	0.0	11.3	22.5	33.8	45.0	56.3	67.5	78.8	90.0
P	17	10.6	0.0	10.6	21.2	31.8	42.4	52.9	63.5	74.1	84.7
Q	18	10.0	0.0	10.0	20.0	30.0	40.0	50.0	60.0	70.0	80.0

	□	Fiber extending direction(relative angle α (degree))

	A	□	□	□	□	□	□	□	□	□
	B	□	□	□	□	□	□	□	□	□
	C	□	□	□	□	□	□	□	□	□
	D	□	□	□	□	□	□	□	□	□
	E	□	□	□	□	□	□	□	□	□
	F	□	□	□	□	□	□	□	□	□
	G	□	□	□	□	□	□	□	□	□
	H	□	□	□	□	□	□	□	□	□
	I	162.0	□	□	□	□	□	□	□	□
	J	147.3	163.6	□	□	□	□	□	□	□
	K	135.0	150.0	165.0	□	□	□	□	□	□
	L	124.6	138.5	152.3	166.2	□	□	□	□	□
	M	115.7	128.6	141.4	154.3	167.1	□	□	□	□
	N	108.0	120.0	132.0	144.0	156.0	168.0	□	□	□
	O	101.3	112.5	123.8	135.0	146.3	157.5	168.8	□	□
	P	95.3	105.9	116.5	127.1	137.6	148.2	158.8	169.4	□
	Q	90.0	100.0	110.0	120.0	130.0	140.0	150.0	160.0	170.0

Table 1 shows examples of 17 quasi-isotropic patterns, classified as Pattern A to Pattern Q. In a quasi-isotropic pattern, the fiber extending directions are equally distributed with equal angular intervals calculated as 180/n, where n is an integer greater than or equal to 2. The symbol “n” refers to the number of angles. In Pattern A, for example, the number n of angles is 2, and the relative angles α indicating the fiber extending directions are 0° and 90°. When using UD prepreg sheets, a prepreg sheet having a fiber extending direction of 0° and a prepreg sheet having a fiber extending direction of 90° are layered to form a layered structure having a quasi-isotropic pattern. The quasi-isotropic pattern achieves symmetry in the fiber extending directions. Although Table 1 shows examples of quasi-isotropic patterns having the number of angles from 2 to 18, the number n of angles may obviously be greater than or equal to 19. From the viewpoint of productivity of the face member f1, the number n of angles can be less than or equal to 18, further can be less than or equal to 10, and still further can be less than or equal to 6. Note that regarding the angular intervals in the quasi-isotropic patterns, variation ranging from −10% to +10% relative to the predetermined angular interval can be considered as a permitted tolerance. Accordingly, each quasi-isotropic pattern does not have to have constant angular intervals. For example, the angular intervals in Pattern E can vary in the range of greater than or equal to 27° and less than or equal to 33°.

The fiber extending directions in Table 1 are indicated by relative angles α. The relative angle α is a relative value that defines the angular difference between the fiber extending directions of the layers. When the face member f1 has a quasi-isotropic pattern, the relationship between the fiber orientation angle θ° and the relative angle α° may be predetermined. Accordingly, for example, the fiber orientation angle θ in the direction where the relative angle α is 0° can be set freely. For example, in the quasi-isotropic pattern A, when the fiber orientation angle θ in the direction where the relative angle α is 0° is set to 45°, the fiber orientation angles θ are 45° and 135°.

FIG. 8A, FIG. 8B, FIG. 9, FIG. 10A, FIG. 10B, FIG. 11A, and FIG. 11B are exploded views schematically illustrating layers superposed on one another in the face member f1. These exploded views are also diagrams illustrating the prepreg sheets constituting the respective layers. In each layer, the fiber extending direction is indicated by hatching lines.

FIG. 8A and FIG. 8B show examples of the quasi-isotropic layered portion T included in the face member f1.

In the embodiment of FIG. 8A, the quasi-isotropic layered portion T is a quasi-isotropic layered portion TC that has the quasi-isotropic pattern C shown in Table 1. The quasi-isotropic pattern C has a number n of angles of 4 and angular intervals of 45°. In the quasi-isotropic layered portion TC of this embodiment, the fiber orientation angle θ in the direction where the relative angle α is 0° is set to 0°. This quasi-isotropic layered portion TC is constituted by a fiber reinforced resin layer S0 having a fiber orientation angle θ of 0°, a fiber reinforced resin layer S45 having a fiber orientation angle θ of 45°, a fiber reinforced resin layer S90 having a fiber orientation angle θ of 90°, and a fiber reinforced resin layer S135 having a fiber orientation angle θ of 135°.

In the embodiment of FIG. 8B, the quasi-isotropic layered portion T is a quasi-isotropic layered portion TE that has the quasi-isotropic pattern E shown in Table 1. The quasi-isotropic pattern E has a number n of angles of 6 and angular intervals of 30°. In the quasi-isotropic layered portion TE, the fiber orientation angle θ in the direction where the relative angle α is 0° is set to 0°. This quasi-isotropic layered portion TE is constituted by a fiber reinforced resin layer S0 having a fiber orientation angle θ of 0°, a fiber reinforced resin layer S30 having a fiber orientation angle θ of 30°, a fiber reinforced resin layer S60 having a fiber orientation angle θ of 60°,a fiber reinforced resin layer S90 having a fiber orientation angle θ of 90°, a fiber reinforced resin layer S120 having a fiber orientation angle θ of 120°, and a fiber reinforced resin layer S150 having a fiber orientation angle θ of 150°.

The order of layers in the quasi-isotropic layered portion T is not limited. Additionally, a layer that does not constitute a part of the quasi-isotropic layered portion T (such as an anisotropy-creating layer described later) may be disposed between the layers of the quasi-isotropic layered portion T. Depending on the wall thickness of the face member f1 and/or other conditions, multiple sets of quasi-isotropic patterns may be layered. In this configuration, the multiple sets of quasi-isotropic patterns may collectively constitute the quasi-isotropic layered portion T. The quasi-isotropic layered portion T may include multiple types of quasi-isotropic patterns.

From the viewpoint of achieving isotropy, the prepreg sheets constituting the respective fiber reinforced resin layers S in the quasi-isotropic layered portion T may have the same specifications as one another, except for a fiber-amount increasing layer Sy and a high elastic layer Sz described later. Examples of the specifications for each prepreg sheet include fiber basis weight (i.e., the weight of fibers per unit area), fiber content, resin content, thickness, and the elastic modulus of fibers (hereinafter, also referred to as fiber elastic modulus). Typically, the fiber content (% by weight) is equivalent to the value calculated by subtracting the resin content (% by weight) from 100. These specifications may be identical for all the fiber reinforced resin layers S constituting the quasi-isotropic layered portion T, except for the fiber-amount increasing layer Sy and the high elastic layer Sz described later. The specifications of the fiber reinforced resin layers S are considered equivalent to the specifications of the respective prepreg sheets used in the fiber reinforced resin layers S. From the viewpoint of enhancing isotropic properties, the same prepreg sheets may be used for the respective fiber reinforced resin layers S constituting the quasi-isotropic layered portion T, except for the fiber-amount increasing layer Sy and the high elastic layer Sz described later. The inclusion of the quasi-isotropic layered portion T ensures the overall strength of the face member f1. Of course, the quasi-isotropic layered portion T may be constituted by prepreg sheets having different specifications. The quasi-isotropic pattern only defines the fiber orientations of the layers.

The face member f1 is constituted by the fiber reinforced resin layers S layered to exhibit anisotropy. Specifically, this anisotropy refers to anisotropy in the rigidity of the face member f1. This anisotropy allows for diverse designs of the rigidity distribution of the face member f1, for example. The face member f1 may include one or more configurations selected from the group consisting of the following: (x), (y), and (z).

• • (x) A configuration that includes a distinct fiber-orientation layer Sx containing fibers oriented at a predetermined fiber orientation angle that is different from the fiber orientation angles of the fiber reinforced resin layers S included in the quasi-isotropic layered portion T.
  • (y) A configuration that includes the fiber-amount increasing layer Sy that relatively increases the amount of fibers at a predetermined fiber orientation angle selected from the fiber orientation angles of the fiber reinforced resin layers S included in the quasi-isotropic layered portion T.
  • (z) A configuration that includes the high elastic layer Sz that has a relatively high fiber elastic modulus at a predetermined fiber orientation angle selected from the fiber orientation angles of the fiber reinforced resin layers S included in the quasi-isotropic layered portion T.

Anisotropy can be created by a configuration that disrupts the mechanical symmetry resulting from fibers extending in directions with equal angular spacing. Examples of such a configuration include the configurations (x), (y), and (z) described above. The distinct fiber-orientation layer Sx, the fiber-amount increasing layer Sy, and the high elastic layer Sz are collectively referred to as anisotropy-creating layers.

FIG. 9 shows an example of the aforementioned configuration (x). This embodiment includes the quasi-isotropic layered portion T (quasi-isotropic layered portion TC) and the distinct fiber-orientation layer Sx. The distinct fiber-orientation layer Sx is not included in the quasi-isotropic layered portion T. The fibers of the distinct fiber-orientation layer Sx are oriented at a fiber orientation angle that is different from the fiber orientation angles of the fiber reinforced resin layers S included in the quasi-isotropic layered portion TC. The distinct fiber-orientation layer Sx has a predetermined fiber orientation angle θ1 as the fiber orientation angle θ. In the present embodiment, the predetermined fiber orientation angle θ1 is 150°.

As described above, the distinct fiber-orientation layer Sx is not included in the quasi-isotropic layered portion T. The distinct fiber-orientation layer Sx may be disposed between the fiber reinforced resin layers S constituting the quasi-isotropic layered portion T.

The fiber elastic modulus of the distinct fiber-orientation layer Sx may be the same as the fiber elastic modulus of each of the fiber reinforced resin layers S in the quasi-isotropic layered portion T. Alternatively, the fiber elastic modulus of the distinct fiber-orientation layer Sx may be greater than the fiber elastic modulus of each of the fiber reinforced resin layers S in the quasi-isotropic layered portion T. This configuration can enhance the advantageous effect of creating anisotropy brought about by the distinct fiber-orientation layer Sx (this advantageous effect of creating anisotropy is hereinafter also referred to as the anisotropy-creating effect). Further alternatively, the fiber elastic modulus of the distinct fiber-orientation layer Sx may be smaller than the fiber elastic modulus of each of the fiber reinforced resin layers S in the quasi-isotropic layered portion T. Since the distinct fiber-orientation layer Sx is an additional layer not included in the quasi-isotropic layered portion T, the presence of the distinct fiber-orientation layer Sx brings about the anisotropy-creating effect irrespective of its fiber elastic modulus.

The fiber basis weight of the distinct fiber-orientation layer Sx may be the same as the fiber basis weight of each of the fiber reinforced resin layers S in the quasi-isotropic layered portion T. Alternatively, the fiber basis weight of the distinct fiber-orientation layer Sx may be greater than the fiber basis weight of each of the fiber reinforced resin layers S in the quasi-isotropic layered portion T. This configuration can enhance the anisotropy-creating effect brought about by the distinct fiber-orientation layer Sx. Further alternatively, the fiber basis weight of the distinct fiber-orientation layer Sx may be smaller than the fiber basis weight of each of the fiber reinforced resin layers S in the quasi-isotropic layered portion T. Since the distinct fiber-orientation layer Sx is an additional layer not included in the quasi-isotropic layered portion T, the presence of the distinct fiber-orientation layer Sx brings about the anisotropy-creating effect irrespective of its fiber basis weight.

FIG. 10A and FIG. 10B show examples of the aforementioned configuration (y).

In the embodiment of FIG. 10A, the quasi-isotropic layered portion T (quasi-isotropic layered portion TE) includes the fiber-amount increasing layer Sy. The fiber-amount increasing layer Sy is included in the quasi-isotropic layered portion TE. Among the layers in the quasi-isotropic layered portion TE, the fiber reinforced resin layer S150 having a fiber orientation angle θ of 150° is the fiber-amount increasing layer Sy. That is, the predetermined fiber orientation angle θ1 in configuration (y) is set to 150°. This fiber reinforced resin layer S150 has a higher fiber basis weight (i.e., the weight of fibers per unit area) compared to the other fiber reinforced resin layers S of the quasi-isotropic layered portion TE. The following (y1) and/or (y2) are examples of methods for increasing the fiber basis weight.

• • (y1) Increase the fiber content. In other words, reduce the resin content.
  • (y2) Increase the thickness (volume).

In the embodiment of FIG. 10B, the fiber-amount increasing layer Sy is provided in addition to the quasi-isotropic layered portion T (quasi-isotropic layered portion TE). The fiber-amount increasing layer Sy is not included in the quasi-isotropic layered portion TE. The fiber orientation angle θ of the fiber-amount increasing layer Sy is the same as the fiber orientation angle θ of any one of the fiber reinforced resin layers S included in the quasi-isotropic layered portion TE. In this embodiment, the specifications of the fiber-amount increasing layer Sy are the same as the specifications of the fiber reinforced resin layer S150 in the quasi-isotropic layered portion TE. By increasing the number of the fiber reinforced resin layers S oriented at a predetermined fiber orientation angle θ1, the amount of fibers at the fiber orientation angle θ1 is relatively increased.

As described above, the fiber-amount increasing layer Sy may be included in the quasi-isotropic layered portion T, or may not be included in the quasi-isotropic layered portion T. The fiber-amount increasing layer Sy can also serve as the high elastic layer Sz.

When the fiber-amount increasing layer Sy is not included in the quasi-isotropic layered portion T, the fiber-amount increasing layer Sy is an additional layer other than the fiber reinforced resin layers S in the quasi-isotropic layered portion T. Accordingly, the presence of the fiber-amount increasing layer Sy brings about the anisotropy-creating effect irrespective of the specifications (fiber basis weight, fiber content, and fiber elastic modulus) of the fiber-amount increasing layer Sy. To enhance the anisotropy-creating effect, the values of the specifications can be increased.

FIG. 11A and FIG. 11B show examples of the aforementioned configuration (z).

In the embodiment of FIG. 11A, the quasi-isotropic layered portion T (quasi-isotropic layered portion TE) includes the high elastic layer Sz. The high elastic layer Sz is included in the quasi-isotropic layered portion TE. Among the layers in the quasi-isotropic layered portion TE, the fiber reinforced resin layer S150 having a fiber orientation angle θ of 150° is the high elastic layer Sz. This fiber reinforced resin layer S150 has a higher fiber elastic modulus (tensile elastic modulus) compared to the other fiber reinforced resin layers S of the quasi-isotropic layered portion TE.

The other fiber reinforced resin layers S in the quasi-isotropic layered portion TE (excluding the high elastic layer Sz) may have fiber elastic moduli that differ from one another. In this configuration, the fiber elastic modulus of the high elastic layer Sz may be greater than the maximum value of the fiber elastic moduli of the other fiber reinforced resin layers S in the quasi-isotropic layered portion TE.

In the embodiment of FIG. 11B, the high elastic layer Sz is provided in addition to the quasi-isotropic layered portion T (quasi-isotropic layered portion TE). The high elastic layer Sz is not included in the quasi-isotropic layered portion TE. The fiber orientation angle θ1 of the high elastic layer Sz is the same as the fiber orientation angle θ of any one of the fiber reinforced resin layers S included in the quasi-isotropic layered portion TE. In the present embodiment, the fiber orientation angle θ1 of the high elastic layer Sz is 150°. That is, the predetermined fiber orientation angle θ1 in configuration (z) is 150°. The high elastic layer Sz, which is not included in the quasi-isotropic layered portion TE, increases the elastic modulus of fibers oriented at the predetermined fiber orientation angle θ1. At the same time, the high elastic layer Sz, which is not included in the quasi-isotropic layered portion TE, increases the amount of fibers at the predetermined fiber orientation angle θ1 (150° in this embodiment). Accordingly, the high elastic layer Sz also serves as the fiber-amount increasing layer Sy.

The fiber reinforced resin layers S in the quasi-isotropic layered portion TE may have fiber elastic moduli that differ from one another. In this configuration, the fiber elastic modulus of the high elastic layer Sz may be greater than or equal to the maximum value of the fiber elastic moduli of the fiber reinforced resin layers S in the quasi-isotropic layered portion TE. The fiber elastic modulus of the high elastic layer Sz may be greater than the maximum value of the fiber elastic moduli of the fiber reinforced resin layers S in the quasi-isotropic layered portion TE.

As described above, the high elastic layer Sz may be included in the quasi-isotropic layered portion T, or may not be included in the quasi-isotropic layered portion T. The high elastic layer Sz can also serve as the fiber-amount increasing layer Sy.

When the high elastic layer Sz is not included in the quasi-isotropic layered portion T, the high elastic layer Sz is an additional layer other than the fiber reinforced resin layers S in the quasi-isotropic layered portion T. Accordingly, the high elastic layer Sz brings about the anisotropy-creating effect irrespective of the fiber basis weight and fiber content of the high elastic layer Sz. To enhance the anisotropy-creating effect, the values of these specifications can be increased.

In the face member f1, all the fiber reinforced resin layers S have a contour shape that is identical to the contour shape of the face member f1. In the face member f1, all the fiber reinforced resin layers S are overall layers that extend across the entirety of the face member f1. The face member f1 is constituted only by the overall layers. The face member f1 has a constant wall thickness. Note that, as used in the present disclosure, the term “constant wall thickness” permits tolerances ranging from −0.1 mm to +0.1 mm. The face member f1 may include one or more partial layers disposed on a part of the face member f1. The wall thickness of the face member f1 does not have to be constant.

FIG. 12 is a front view illustrating an example of anisotropy of the face member f1. For example, introducing anisotropy to the flexural rigidity of the face member f1 can selectively reduce its flexural rigidity in a specific region. In the embodiment of FIG. 12, the flexural rigidity is reduced in a region R1 that extends from the heel lower side to the toe upper side of the face member f1. In FIG. 12, the region R1 is indicated with broken line hatching. This configuration causes a larger deformation in the region R1 of the face portion 10 when the head 4 strikes a golf ball, which can enhance rebound performance. The region R1 can function as an area that exhibits high rebound performance (hereinafter, such an area is also referred to as a high rebound area). This head 4 is effective for a golfer whose impact region, where golf ball impact points are located with high probability, approximately coincides with the region R1 (hereinafter, such a region where golf ball impact points are located with high probability is also referred to as an “impact point distribution region”).

For example, when the orientation angle θ2 of the lengthwise direction D2 of the region R1 is 60°, the distinct fiber-orientation layer Sx, the fiber-amount increasing layer Sy, or the high elastic layer Sz can be disposed such that the fiber orientation angle θ1 of its fiber extending direction D1 is 150°. The fiber extending direction D1 is perpendicular to the lengthwise direction D2. The flexural rigidity is reduced in the direction perpendicular to the fiber extending direction D1. By setting the predetermined fiber orientation angle θ1 in the direction perpendicular to the lengthwise direction D2, the lengthwise direction D2 of the region R1 can be oriented in an intended direction.

All five embodiments described with reference to FIG. 9 through FIG. 11 can be employed as a layered configuration to achieve the region R1 shown in FIG. 12. In the embodiment of FIG. 9, since the fiber orientation angle θ1 of the distinct fiber-orientation layer Sx is 150°, the orientation angle θ2 of the region R1 can be set to 60°. In the embodiments of FIG. 10A and FIG. 10B, since the fiber orientation angle θ1 of the fiber-amount increasing layer Sy is 150°, the orientation angle θ2 of the region R1 can be set to 60°. In the embodiments of FIG. 11A and FIG. 11B, since the fiber orientation angle θ1 of the high elastic layer Sz is 150°, the orientation angle θ2 of the region R1 can be set to 60°.

FIG. 13 is a perspective view of a head 40 according to a second embodiment. FIG. 14 is a plan view of the head 40 as viewed from the crown side. FIG. 15 is a front view of the head 40 as viewed from the face side. FIG. 16 is an exploded perspective view of the head 40. FIG. 17 is a cross-sectional view taken along line A-A in FIG. 14.

As shown in FIG. 13, the head 40 includes a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 includes a striking face 10a. The striking face 10a is the outer surface of the face portion 10.

As shown in FIG. 16, from the viewpoint of constituent members, the head 40 includes a face member f2 and a body member b1. The face member f2 is fixed to the body member b1.

The face member f2 includes a resin layer f3 and a body part f4. The body part f4 is made of a fiber reinforced resin. The body part f4 has the same configuration as the face member f1 of the first embodiment. The resin layer f3 is made of a resin that does not contain fibers. The resin layer f3 is the outermost layer of the face member f2. The resin layer f3 forms the front surface f10 of the face member f2. The resin layer f3 forms the striking face 10a. The difference between the head 40 of the present embodiment and the head 4 of the first embodiment is only the presence or absence of the resin layer f3.

Examples of the resin used as the material for the resin layer f3 include synthetic resins and natural resins. Examples of synthetic resins include thermoplastic resins and thermosetting resins. Synthetic resins include elastomers. Elastomers include synthetic rubbers. The presence of the resin layer f3 can improve ball sticking feel and feel at impact with a golf ball. The term “ball sticking feel” refers to a feel in which the ball adheres to the striking face 10a without slipping on the striking face 10a during impact.

The method for producing the resin layer f3 is not limited. For example, the resin layer f3 may be formed separately from the body part f4 and subsequently attached to the body part f4. Alternatively, for example, the resin layer f3 may be placed on the body part f4 within a mold during molding. Further alternatively, the resin layer f3 may be provided as a coating film. The resin layer f3 can be formed on the body part f4 by, for example, the following methods.

• • (1) Prepare the resin layer f3 formed separately from the body part f4, and subsequently adhere the resin layer f3 to the surface of the body part f4 with an adhesive.
  • (2) Prepare a tentative resin layer f3 formed separately from the body part f4; apply a primer to a part of the body part f4 where the resin layer f3 is to be disposed; place the tentative resin layer f3 on the primer of the body part f4 and set them into a mold; and form the resin layer f3 by heating and melting the tentative resin layer f3 in the mold.
  • (3) Place unreacted resin raw material into a mold in which the body part f4 has already been set; and cause a reaction to form the resin layer f3 on the body part f4.
  • (4) Subject a thermoplastic resin to injection molding (insert molding) in a mold in which the body part f4 has already been set to form the resin layer f3 on the body part f4.

Examples of the resin used as the material for the resin layer f3 include synthetic resins and natural resins.

A polyurethane may be used for the resin as the material of the resin layer f3. The polyurethane has excellent strength and abrasion resistance. The polyurethane is a polymer having a urethane bond. Examples of the polyurethane include a thermoplastic polyurethane and a thermosetting polyurethane. The thermoplastic polyurethane is a polyurethane that exhibits plasticity by heating. In general, the thermoplastic polyurethane means a polyurethane having a linear chain structure of a high molecular weight to a certain extent. The thermosetting polyurethane is a polyurethane obtained by polymerization through a reaction between a low molecular weight urethane prepolymer and a curing agent (chain extender) when forming the resin layer f3. The thermosetting polyurethane is also referred to as two-component curing type polyurethane. Examples of the thermosetting polyurethane include a polyurethane having a linear chain structure and a polyurethane having a three-dimensional crosslinked structure, which can be obtained by controlling the number of the functional group of the prepolymer or curing agent (chain extender). The polyurethane may be a thermoplastic elastomer.

The thermoplastic polyurethane is not limited, as long as the thermoplastic polyurethane has a plurality of polyurethane bonds within a molecule and exhibits thermo-plasticity. For example, the thermoplastic polyurethane includes a reaction product having a urethane bond formed in a molecule by reacting a polyisocyanate with a polyol, and further with a polyamine as necessary.

The polyisocyanate component constituting the thermoplastic polyurethane is not particularly limited, as long as the polyisocyanate component has two or more isocyanate groups. Examples of the polyisocyanate component include an aromatic polyisocyanate such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3′-bitolylene-4,4′-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), para-phenylene diisocyanate (PPDI); and an alicyclic polyisocyanate or aliphatic polyisocyanate such as 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI), hydrogenated xylylene diisocyanate (H₆XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI). The above polyisocyanate components may be used solely or as a mixture of two or more of them.

From the viewpoint of enhancing abrasion resistance, the polyisocyanate component of the polyurethane is preferably the aromatic polyisocyanate. When the aromatic polyisocyanate is used, the resultant polyurethane has enhanced mechanical properties, and thus the obtained resin layer f3 has excellent abrasion resistance. Further, from the viewpoint of enhancing weather resistance, the polyisocyanate component of the polyurethane is preferably a non-yellowing polyisocyanate (such as TMXDI, XDI, HDI, H₆XDI, IPDI, H₁₂MDI, and NBDI), and more preferably 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI). Since 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI) has a rigid structure, the resultant polyurethane has enhanced mechanical properties, and the obtained resin layer f3 has excellent abrasion resistance. From the viewpoint of improving the ball sticking feel, another polyisocyanate component may be selected.

The polyol component constituting the thermoplastic polyurethane is not particularly limited as long as the polyol component has a plurality of hydroxyl groups. Examples of the polyol component include a low molecular weight polyol and a high molecular weight polyol. Examples of the low molecular weight polyol include a diol such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; and a trial such as glycerin, trimethylolpropane, and hexanetriol. Examples of the high molecular weight polyol include a polyether polyol such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG); a condensed polyester polyol such as polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA); a lactone polyester polyol such as poly-ε-caprolactone (PCL); a polycarbonate polyol such as polyhexamethylene carbonate; and an acrylic polyol. The above polyol components may be used solely or as a mixture of two or more of them.

An average molecular weight of the high molecular weight polyol is not particularly limited, and is preferably, for example, greater than or equal to 400, and more preferably greater than or equal to 1000. This is because an excessively small average molecular weight of the high molecular weight polyol makes the resultant polyurethane hard, which can result in deterioration of feel at impact with a golf ball. An upper limit of the average molecular weight of the high molecular weight polyol is not particularly limited, and it is preferably less than or equal to 10000, and more preferably less than or equal to 8000.

The polyamine which can constitute the thermoplastic polyurethane as necessary is not particularly limited, as long as it has at least two amino groups. Examples of the polyamine include an aliphatic polyamine such as ethylene diamine, propylene diamine, butylene diamine, and hexamethylene diamine; an alicyclic polyamine such as isophorone diamine, and piperazine; and an aromatic polyamine.

The aromatic polyamine is not particularly limited, as long as it has at least two amino groups directly or indirectly bonded to an aromatic ring. Herein, the “indirectly bonded to an aromatic ring” means that the amino groups are bonded to an aromatic ring via, for example, a lower alkylene group. The aromatic polyamine may be, for example, a monocyclic aromatic polyamine having at least two amino groups bonded to one aromatic ring, or a polycyclic aromatic polyamine having at least two aminophenyl groups each having at least one amino group bonded to one aromatic ring.

Examples of the monocyclic aromatic polyamine include: a type wherein amino groups such as phenylenediamine, tolylenediamine, diethyltoluenediamine, and dimethylthiotoluenediamine, are directly bonded to an aromatic ring; and a type wherein amino groups such as xylylenediamine are bonded to an aromatic ring via a lower alkylene group. Further, the polycyclic aromatic polyamine may be either a poly(aminobenzene) having at least two aminophenyl groups directly bonded to each other, or a compound having at least two aminophenyl groups bonded to each other via a lower alkylene group or an alkylene oxide group. Among them, a diaminodiphenylalkane having two aminophenyl groups bonded to each other via a lower alkylene group is preferable, and 4,4′-diaminodiphenylmethane and a derivative thereof are particularly preferable.

The configuration of the thermoplastic polyurethane is not particularly limited. Examples of the configuration include: a configuration where the thermoplastic polyurethane is composed of the polyisocyanate component and the high molecular weight polyol component; a configuration where the thermoplastic polyurethane is composed of the polyisocyanate component, the high molecular weight polyol component and the low molecular weight polyol component; a configuration where the thermoplastic polyurethane is composed of the polyisocyanate component, the high molecular weight polyol component, the low molecular weight polyol component and the polyamine component; and a configuration where the thermoplastic polyurethane is composed of the polyisocyanate component, the high molecular weight polyol component and the polyamine component.

Examples of the thermoplastic polyurethane include an MDI-based polyurethane in which MDI is used as the polyisocyanate component, and a hydrogenated MDI-based polyurethane in which H₁₂MDI is used as the polyisocyanate component.

Specific examples of the thermoplastic polyurethane include product names “Elastollan XNY90A”, “Elastollan XNY97A”, “Elastollan XNY585”, “Elastollan 1180A10”, “Elastollan 1185A50”, “Elastollan 1190A10TR”, “Elastollan 1195A50STR” and “Elastollan 1164D50” put on the market by BASF Japan Ltd.

The resin used as the material for the resin layer f3 is not particularly limited as long as the resin is contained as a basis resin component. For example, when the resin is a polyurethane, the resin is not specifically limited as long as the resin contains the polyurethane as a basis resin component. When the polyurethane is a thermoplastic polyurethane, the content of the thermoplastic polyurethane contained in the resin component constituting the material of the resin layer f3 is preferably greater than or equal to 50% by weight, more preferably greater than or equal to 70% by weight, and still more preferably greater than or equal to 90% by weight. In addition, it is also preferable that the resin component constituting the material of the resin layer f3 substantially consists only of a polyurethane (for example, only a thermoplastic polyurethane).

In addition to the resin component, the material of the resin layer f3 may further contain, for example, a pigment component such as a white pigment (e.g. titanium oxide), a blue pigment and a red pigment, a weight adjusting agent such as calcium carbonate and barium sulfate, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent material or fluorescent brightener, as long as they do not impair the performance of the resin layer f3.

The Shore D hardness of the striking face 10a formed by the resin layer f3 is not limited. From the viewpoint of feel at impact with a golf ball, the Shore D hardness can be set within a predetermined range. The lower limit of the Shore D hardness of the striking face 10a can be greater than or equal to 65, further can be greater than or equal to 70, and still further can be greater than or equal to 75. The upper limit of the Shore D hardness of the striking face 10a can be less than or equal to 99, further can be less than or equal to 95, and still further can be less than or equal to 90.

The Shore D hardness of the striking face 10a is measured in a finished head. After a head is stored at a temperature of 23° C. for two weeks, the hardness of the striking face 10a of the head is measured using ASKER Durometer Type D. The measurement is performed by pressing the durometer against the striking face 10a of the head. The number n of times of the measurements is 10. The average value of 10 data is considered as a measured value. The Shore D hardness is measured at a position where the score lines are not present. When the resin material constituting the resin layer f3 is measured independently, its Shore D hardness may be less than or equal to 40. However, when the Shore D hardness is measured in a state where the resin layer f3 is attached to the body part f4, the measured Shore D hardness increases because the durometer needle penetrates the resin layer f3 and comes into contact with the body part f4.

The thickness of the resin layer f3 is not limited. From the viewpoint of the ball sticking feel, the thickness of the resin layer f3 is preferably greater than or equal to 0.3 mm, more preferably greater than or equal to 0.32 mm, and still more preferably greater than or equal to 0.35 mm. From the viewpoint of rebound performance, the thickness of the body part f4 is preferably less than or equal to 0.8 mm, more preferably less than or equal to 0.7 mm, and still more preferably less than or equal to 0.6 mm. The thickness of the body part f4 is measured in the direction normal to the striking face 10a.

The above-described embodiments exhibit the following advantageous effects. In the following description, the term “face member f1, f2” is used when referring to both the face member f1 and the face member f2.

The presence of the quasi-isotropic layered portion T ensures the overall strength of the face member f1, f2. Additionally, anisotropy can be introduced to the face member f1, f2 by providing one or more layers selected from the distinct fiber-orientation layer Sx, the fiber-amount increasing layer Sy, and the high elastic layer Sz. This anisotropy makes it possible to design an intended rigidity distribution of the face member f1, f2. Specifically, the anisotropy enables the design of a high rebound area, for example. The quasi-isotropic layered portion T includes at least one type of quasi-isotropic pattern. The quasi-isotropic layered portion T may include two or more different types of quasi-isotropic patterns. For example, the quasi-isotropic layered portion T may include the quasi-isotropic pattern C and the quasi-isotropic pattern E.

A predetermined fiber orientation angle θ1 can be set for each of the distinct fiber-orientation layer Sx, the fiber-amount increasing layer Sy, and the high elastic layer Sz. Setting the predetermined fiber orientation angle θ1 can reduce the flexural rigidity of the region R1 in the direction perpendicular to the fiber orientation angle θ1. This results in the region R1 being a high rebound area. Since the high rebound area can be designed by setting the predetermined fiber orientation angle θ1, the design process is simplified.

The anisotropy-creating layers Sx, Sy, and Sz may have one fiber orientation angle θ1, or may have two or more fiber orientation angles θ1. For example, multiple distinct fiber-orientation layers Sx may be provided, with their respective fiber orientation angles θ differing from one another. In this configuration, the average value of these fiber orientation angles θ can be defined as the predetermined fiber orientation angle θ1.

When the predetermined fiber orientation angle θ1 is 90°, the region R1 exhibiting a high rebound performance extends in the 0° direction. On the other hand, the impact point distribution region on the striking face 10a tends to extend in an inclined direction. From this viewpoint, the predetermined fiber orientation angle θ1 may be set to an angle other than 90°.

When the predetermined fiber orientation angle θ1 is 0°, the region R1 exhibiting a high rebound performance extends in the 90° direction. On the other hand, the impact point distribution region on the striking face 10a tends to extend in an inclined direction. From this viewpoint, the predetermined fiber orientation angle θ1 may be set to an angle other than 0°.

The predetermined fiber orientation angle θ1 may be greater than 90° and less than 180°. The impact point distribution region can extend from the toe upper side to the heel lower side of the striking face 10a. By setting the predetermined fiber orientation angle θ1 within the range of 90°<θ1<180°, the region extending from the toe upper side to the heel lower side can become a high rebound area. In the embodiment of FIG. 12, the predetermined fiber orientation angle θ1 is set to 150°. As a result, the region R1, extending from the toe upper side to the heel lower side along the direction D2, is the high rebound area.

When the club has a long length, the impact point distribution region tends to extend from the toe upper side to the heel lower side. From this viewpoint, when the real loft angle is less than 15° (and greater than or equal to 7°), the predetermined fiber orientation angle θ1 may be set to greater than or equal to 105° and less than or equal to 135°. In this configuration, the orientation angle θ2 (see FIG. 12) of the region R1 can be greater than or equal to 15° and less than or equal to 45°. When the club has a relatively short length, the real loft angle increases, and the variation of impact points in the up-down direction also increases. In this configuration, the direction in which the impact point distribution region extends tends to become more horizontal. From this viewpoint, when the real loft angle is greater than or equal to 15° (and less than or equal to) 35°, the predetermined fiber orientation angle θ1 may be set to greater than or equal to 90° and less than or equal to 120°. In this configuration, the orientation angle θ2 (see FIG. 12) of the region R1 can be greater than or equal to 0° and less than or equal to 30°. The position of the impact point distribution region may differ depending on the club length. By setting the predetermined fiber orientation angle θ1 according to the real loft angle, which varies with club length, the high rebound area can be made to coincide with the impact point distribution region. When the real loft angle is less than 15° (and greater than or equal to 7°), the club length can be greater than or equal to 43.5 inches (and less than or equal to 47 inches). A head having a real loft angle of less than 15° (and greater than or equal to 7°) is preferably a large-sized head as described later, and more preferably a driver head. When the real loft angle is greater than or equal to 15° (and less than or equal to 35°), the club length can be less than 43.5 inches (and greater than or equal to 39 inches). A head having a real loft angle of greater than or equal to 15° (and less than or equal to) 35° is preferably a medium-sized head or a small-sized head as described later, and more preferably a fairway wood type head or a hybrid type head. The club length is measured in accordance with the regulations defined by the R&A (the Royal and Ancient Golf Club of Saint Andrews). The regulations are described in “1 c Length” in “1 Clubs” of “Appendix II Design of Clubs” in the latest version of Rules of Golf issued by the R&A. This measurement method is also referred to as the “60-degree measurement method” because it is performed by placing the club on a horizontal plane and resting the sole against a plane that is inclined at a 60-degree angle relative to the horizontal plane. The club length can be converted into millimeters, with 1 inch being equivalent to 25.4 millimeters.

In the face member f1, f2, the rigidity distribution is designed through anisotropy, eliminating the need for wall thickness distribution to achieve the desired rigidity distribution. If wall thickness distribution were to be provided in the face member f1, f2 made of fiber reinforced resin, a partial layer disposed only in a part of the face member f1, f2 would be necessary. The presence of such a partial layer creates a step at its edge, and the step can lead to void formation. The voids can reduce the durability of the face member f1, f2. By making all the fiber reinforced resin layers S overall layers, void formation can be suppressed. This can enhance the durability of the face member f1, f2. From this viewpoint, the face member f1, f2 does not have to have wall thickness distribution. In other words, the face member f1, f2 may have a constant wall thickness.

The rigidity distribution of the face member f1, f2 is designed through anisotropy created by fiber orientation, eliminating the need for wall thickness distribution in the face member f1, f2 to achieve the desired rigidity distribution. When the face member f1, f2 has a constant wall thickness, strength reduction due to the presence of a thin-wall portion can be prevented.

The wall thickness of the face member f1, f2 is not limited. From the viewpoint of durability, the wall thickness of the face member f1, f2 is preferably greater than or equal to 3.0 mm, more preferably greater than or equal to 3.5 mm, and still more preferably greater than or equal to 4.0 mm. From the viewpoint of weight reduction of the face portion 10, the wall thickness of the face member f1, f2 is preferably less than or equal to 9.0 mm, more preferably less than or equal to 8.5 mm, and still more preferably less than or equal to 8.0 mm. The wall thickness of the face member f1, f2 can be set by adjusting the number of layers according to the thicknesses of the prepreg sheets being used.

The thickness of each prepreg sheet is not limited. Additionally, the number of prepreg sheets (the total number of the fiber reinforced resin layers S layered to constitute the face member f1, f2) is not limited. An excessively small number of layers reduces the flexibility in designing fiber orientations. From this viewpoint, the thickness of each prepreg sheet can be less than or equal to 0.15 mm, further can be less than or equal to 0.14 mm, and still further can be less than or equal to 0.13 mm. An excessively large number of layers can reduce productivity. From this viewpoint, the thickness of each prepreg sheet can be greater than or equal to 0.02 mm, further can be greater than or equal to 0.03 mm, still further can be greater than or equal to 0.05 mm, and yet further can be greater than or equal to 0.06 mm. From the viewpoint of the flexibility in designing fiber orientations, the total number of the fiber reinforced resin layers S can be greater than or equal to 20, further can be greater than or equal to 30, still further can be greater than or equal to 35, and yet further can be greater than or equal to 40. From the viewpoint of productivity, the total number of the fiber reinforced resin layers S can be less than or equal to 80, further can be less than or equal to 70, still further can be less than or equal to 65, and yet further can be less than or equal to 60.

From the viewpoint of effectively creating anisotropy, the ratio of the number of anisotropy-creating layers to the total number of layers can be greater than or equal to 10%, further can be greater than or equal to 13%, and still further can be greater than or equal to 16%. From the viewpoint of the overall strength of the face member f1, f2, the ratio of the number of anisotropy-creating layers to the total number of layers can be less than or equal to 40%, further can be less than or equal to 35%, and still further can be less than or equal to 30%.

When multiple anisotropy-creating layers are provided, all the anisotropy-creating layers may be arranged together at a single position in the layered structure, or the anisotropy-creating layers may be arranged at separate positions in the layered structure. From the viewpoint of the strength of the face member f1, f2, it is preferable that the multiple anisotropy-creating layers are arranged at two or more separate positions in the layered structure. It is preferable that the quasi-isotropic layered portion T is disposed between the anisotropy-creating layers. When multiple sets of laminations, each having their respective quasi-isotropic patterns, are provided, the anisotropy-creating layers may be disposed between these sets.

From the viewpoint of the strength of the face member f1, it is preferable that the anisotropy-creating layers are not located at the outermost layer of the face member f1, and more preferably are not located at either the outermost layer or the innermost layer of the face member f1. From the viewpoint of the strength of the face member f2, it is preferable that the anisotropy-creating layers are not located at the outermost layer of the body part f4, and more preferably are not located at either the outermost layer or the innermost layer of the body part f4.

The face member f1 (body part f4) may have either a constant wall thickness or a varying wall thickness. As described above, the rigidity distribution of the face member f1, f2 can be achieved through anisotropy, eliminating the need for thickness distribution created by a partial layer. Excluding the use of a partial layer suppresses void formation and improves durability. From this viewpoint, it is preferable that all layers constituting the face member f1 (body part f4) are overall layers. In this configuration, the wall thickness of the face member f1 (body part f4) can be constant. From the viewpoint of excluding the use of a partial layer, the face member f1 (body part f4) preferably has a constant wall thickness.

In the head 40 of the second embodiment, the resin layer f3 containing no fibers is provided as the outermost layer. The resin layer f3 can improve the ball sticking feel and feel at impact with a golf ball. Additionally, the resin layer f3 can increase the backspin rate.

The matrix resin of the fiber reinforced resin layers S is not limited. Examples of the matrix resin include an epoxy resin. The hardness of the matrix resin in the fiber reinforced resin layer S forming the front surface f10 of the face member f1 may be lower than the hardness of the matrix resin in the other fiber reinforced resin layers S. This configuration can increase the backspin rate.

The center of gravity of the face member f1, f2 may be positioned closer to its rear than to its front within the face member f1, f2. In other words, the shortest distance between the center of gravity of the face member f1, f2 and the rear surface f11 may be less than the shortest distance between the center of gravity of the face member f1, f2 and the front surface f10. This position of the center of gravity can be achieved by creating a difference in specific gravity among the fiber reinforced resin layers S constituting the face member f1, f2. The difference in specific gravity among the fiber reinforced resin layers S can be created by differences in the specific gravities of the matrix resins or fibers. This position of the center of gravity is useful for increasing the depth of the center of gravity of the head, where “depth” refers to the distance from the center of gravity of the head to the striking face 10a in the face-back direction.

A glass fiber reinforced resin layer containing glass fibers as the reinforcing fibers may be disposed at a position on the rear side relative to the center in the thickness direction of the face member f1, f2. The glass fiber reinforced resin layer may be disposed as the innermost layer forming the rear surface f11. Glass fibers exhibit excellent durability against impact. The glass fiber reinforced resin layer disposed closer to the rear than to the front within the face member f1, f2 can enhance the impact resistance of the face member f1, f2. This can increase the strength of the face member f1, f2 against impact with a golf ball.

The head volume is not limited. Each of the heads 4 and 40 may be a large-sized head having a head volume of greater than or equal to 400 cm³. In this configuration, the area of the front surface f10 of the face member f1, f2 can be greater than or equal to 3000 mm². In this configuration, the weight of the face member f1, f2 can be less than or equal to 35 g, further can be less than or equal to 34 g, and still further can be less than or equal to 33 g. The weight of the face member f1, f2 can be reduced by the fiber reinforced resin layers S. Reducing the weight of the face member f1, f2 allows the saved weight to be allocated to desired portions of the body member b1, which can improve the flexibility in designing the body member b1. In such a large-sized head, from the viewpoint of strength, the weight of the face member f1, f2 can be greater than or equal to 25 g, further can be greater than or equal to 26 g, and still further can be greater than or equal to 27 g. In such a large-sized head, the head volume can be less than or equal to 470 cm³, and the area of the front surface f10 of the face member f1, f2 can be less than or equal to 4800 mm². Such a large-sized head can be preferably used for driver heads.

Each of the heads 4 and 40 may be a medium-sized head having a head volume of less than 300 cm³. In this configuration, the area of the front surface f10 of the face member f1, f2 can be greater than or equal to 2000 mm². In this configuration, the weight of the face member f1, f2 can be less than or equal to 25 g, further can be less than or equal to 24 g, and still further can be less than or equal to 23 g. The weight of the face member f1, f2 can be reduced by the fiber reinforced resin layers S. Reducing the weight of the face member f1, f2 allows the saved weight to be allocated to desired portions of the body member b1, which can improve the flexibility in designing the body member b1. In such a medium-sized head, from the viewpoint of strength, the weight of the face member f1, f2 can be greater than or equal to 13 g, further can be greater than or equal to 14 g, and still further can be greater than or equal to 15 g. In such a medium-sized head, the head volume can be greater than 200 cm³, and the area of the front surface f10 of the face member f1, f2 can be less than or equal to 3500 mm². Such a medium-sized head can be preferably used for fairway wood type heads.

Each of the heads 4 and 40 may be a small-sized head having a head volume of less than or equal to 200 cm³. In this configuration, the area of the front surface f10 of the face member f1, f2 can be greater than or equal to 1800 mm². In this configuration, the weight of the face member f1, f2 can be less than or equal to 20 g, further can be less than or equal to 19 g, and still further can be less than or equal to 18 g. The weight of the face member f1, f2 can be reduced by the fiber reinforced resin layers S. Reducing the weight of the face member f1, f2 allows the saved weight to be allocated to desired portions of the body member b1, which can improve the flexibility in designing the body member b1. In such a small-sized head, from the viewpoint of strength, the weight of the face member f1, f2 can be greater than or equal to 12 g, further can be greater than or equal to 13 g, and still further can be greater than or equal to 14 g. In such a small-sized head, the head volume can be greater than or equal to 80 cm³, and the area of the front surface f10 of the face member f1, f2 can be less than or equal to 3000 mm². Such a small-sized head can be preferably used for hybrid type heads.

EXAMPLES

Example 1

A head having the same configuration as the head 4 of the first embodiment was produced. All layers of the face member were formed using prepreg sheets each having a thickness of 0.08 mm, a carbon fiber basis weight of 132 g/m², a resin content of 24% by weight (corresponding to a fiber content of 76% by weight), and a fiber elastic modulus of 24 t/mm². The layered configuration illustrated in FIG. 9 was employed. The quasi-isotropic layered portion TC having the quasi-isotropic pattern C was employed as the quasi-isotropic layered portion T. Ten sets, each including four prepreg sheets having the quasi-isotropic pattern C, were prepared. One distinct fiber-orientation layer Sx having a fiber orientation angle θ of 150° was disposed between each pair of adjacent sets. In total, 40 prepreg sheets, constituting the quasi-isotropic layered portions TC, and 9 fiber reinforced resin layers S150, forming the distinct fiber-orientation layers Sx, were layered. The total number of layers was 49. All of the prepreg sheets were cut into the same shape as the face member f1, layered, and then subjected to heating and pressurization in a mold to produce the face member f1. A titanium alloy was subjected to lost-wax precision casting to produce the body member b1. The face member f1 was bonded to the opening 18 of the body member b1 using an adhesive to produce the head of Example 1.

Example 2

The layered configuration illustrated in FIG. 10A was employed. The quasi-isotropic layered portion TE having the quasi-isotropic pattern E was employed as the quasi-isotropic layered portion T. Eight sets, each including six prepreg sheets having the quasi-isotropic pattern E, were prepared. In each of these sets, the fiber-amount increasing layer Sy was used as the fiber reinforced resin layer S150 having a fiber orientation angle θ of 150°. As this fiber-amount increasing layer Sy, a prepreg sheet having a thickness of 0.10 mm, a carbon fiber basis weight of 165 g/m², a resin content of 24% by weight (corresponding to a fiber content of 76% by weight), and a fiber elastic modulus of 24 t/mm² was employed. The other layers were formed using the same prepreg sheets as in Example 1. The fiber basis weight of the prepreg sheet for the fiber-amount increasing layer Sy was 165 g/m², which was greater than the fiber basis weight of the other prepreg sheets (132 g/m²). These eight sets were layered. In total, 48 prepreg sheets, constituting the quasi-isotropic layered portions TE, were layered. Of the 48 prepreg sheets, 8 prepreg sheets were the fiber-amount increasing layers Sy. The fiber-amount increasing layer Sy was disposed at an identical position within each of the eight sets of the layered configurations. As a result, the fiber-amount increasing layers Sy were disposed separately from one another. The total number of layers was 48. Except for the above-described matters, the head of Example 2 was obtained in the same manner as in Example 1.

Example 3

The layered configuration illustrated in FIG. 11B was employed. The quasi-isotropic layered portion TE having the quasi-isotropic pattern E was employed as the quasi-isotropic layered portion T. Seven sets, each including six prepreg sheets having the quasi-isotropic pattern E, were prepared. One high elastic layer Sz having a fiber orientation angle θ of 150° was disposed between each pair of adjacent sets. As this high elastic layer Sz, a prepreg sheet having a thickness of 0.08 mm, a carbon fiber basis weight of 132 g/m², a resin content of 25% by weight (corresponding to a fiber content of 75% by weight), and a fiber elastic modulus of 40 t/mm² was employed. The other layers were formed using the same prepreg sheets as in Example 1. The fiber elastic modulus of the prepreg sheet for the high elastic layer Sz was 40 t/mm², which was greater than the fiber elastic modulus of the other prepreg sheets (24 t/mm²). In total, 42 prepreg sheets, constituting the quasi-isotropic layered portions TE, and 6 fiber reinforced resin layers S150, forming the high elastic layers Sz, were layered. The total number of layers was 48. Except for the above-described matters, the head of Example 3 was obtained in the same manner as in Example 1.

Example 4

A resin layer f3 was bonded to the surface of the face member f1 obtained in Example 1 using an adhesive. A sheet made of an MDI-based polyurethane was used as the resin layer f3.

In the heads of Examples 1 to 4, the region extending in the direction at 90° relative to the fiber orientation angle θ of the anisotropy-creating layers Sx, Sy, or Sz exhibited relatively high rebound performance.

Regarding the above-described embodiments, the following clauses are disclosed.

Clause 1

A golf club head includes: a face member including a plurality of fiber reinforced resin layers; and a body member, wherein

• • the face member includes a quasi-isotropic layered portion in which at least some of the fiber reinforced resin layers are superposed on one another such that relative angles of fiber orientations of the respective fiber reinforced resin layers form a quasi-isotropic pattern,
  • the face member further includes one or more configurations selected from a group consisting of the following (x), (y), and (z):
  • (x) a configuration that includes a distinct fiber-orientation layer containing fibers oriented at a predetermined fiber orientation angle that is different from fiber orientation angles of the fiber reinforced resin layers included in the quasi-isotropic layered portion;
  • (y) a configuration that includes a fiber-amount increasing layer that relatively increases an amount of fibers at a predetermined fiber orientation angle selected from the fiber orientation angles of the fiber reinforced resin layers included in the quasi-isotropic layered portion; and
  • (z) a configuration that includes a high elastic layer that has a relatively high fiber elastic modulus at a predetermined fiber orientation angle selected from the fiber orientation angles of the fiber reinforced resin layers included in the quasi-isotropic layered portion.

Clause 2

The golf club head according to clause 1, wherein

• • all the fiber reinforced resin layers are overall layers that extend across an entirety of the face member.

Clause 3

The golf club head according to clause 1 or 2, wherein

• • the face member has a constant wall thickness.

Clause 4

The golf club head according to any one of clauses 1 to 3, wherein

• • a toe-heel direction is designated as 0°, and the fiber orientation angles are defined as angles measured clockwise from 0°, and
  • the predetermined fiber orientation angle is greater than or equal to 90° and less than 180°.

Clause 5

The golf club head according to any one of clauses 1 to 4, wherein

• • the distinct fiber-orientation layer, the fiber-amount increasing layer, and the high elastic layer are collectively referred to as anisotropy-creating layers, and
  • the anisotropy-creating layers are not located at an outermost layer of the face member.

Clause 6

The golf club head according to any one of clauses 1 to 5, wherein

• • the face member further includes a resin layer that contains no fibers; and
  • the resin layer is an outermost layer of the face member.

List of Reference Symbols

• • 4, 40 Head
  • 10 Face portion
  • 10a Striking face
  • 12 Crown portion
  • 14 Sole portion
  • 16 Hosel portion
  • 18 Opening
  • 20 Hollow interior
  • S Fiber reinforced resin layer
  • Sx Distinct fiber-orientation layer (Anisotropy-creating layer)
  • Sy Fiber-amount increasing layer (Anisotropy-creating layer)
  • Sz High elastic layer (Anisotropy-creating layer)
  • S0 Fiber reinforced resin layer having a fiber orientation angle θ of 0°
  • S45 Fiber reinforced resin layer having a fiber orientation angle θ of 45°
  • S90 Fiber reinforced resin layer having a fiber orientation angle θ of 90°
  • S135 Fiber reinforced resin layer having a fiber orientation angle θ of 135°
  • S30 Fiber reinforced resin layer having a fiber orientation angle θ of 30°
  • S60 Fiber reinforced resin layer having a fiber orientation angle θ of 60°
  • S120 Fiber reinforced resin layer having a fiber orientation angle θ of 120°
  • S150 Fiber reinforced resin layer having a fiber orientation angle θ of 150°
  • T Quasi-isotropic layered portion
  • f1, f2 Face member
  • f3 Resin layer of the face member
  • f4 Body part of the face member
  • f10 Front surface of the face member
  • f11 Rear surface of the face member
  • b1 Body member
  • Fc Face center

The above descriptions are merely illustrative and various modifications can be made without departing from the principles of the present disclosure.

The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The use of the terms “a”, “an”, “the”, and similar referents in the context of throughout this disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. As used throughout this disclosure, the word “may” is used in a permissive sense (i.e., meaning “having the potential to”), rather than the mandatory sense (i.e., meaning “must”). Similarly, as used throughout this disclosure, the terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted.