Golf club head

Abstract

The present invention provides a golf club head capable of achieving both rebound performance and bite feeling. The golf club head (100) is provided with a club face portion (102) forming a hitting face (102a). The face section (102) has a metal face section (M1) formed from a metal, and a polyurethane layer section (U1) formed from a polyurethane, the polyurethane layer section (U1) being provided on the outside of the metal face section (M1). In the portion covered by the polyurethane layer portion (U1), the linear roughness of the outer surface of the metal rod surface portion (M1) is such that the arithmetic average roughness Ra is greater than 4.5 [mu] m or the maximum height Rz is greater than 25 [mu] m. In the golf club head (100), the linear roughness of the outer surface of the metal face portion (M1) may be such that the arithmetic average roughness Ra is greater than 4.5 [mu] m and the maximum height Rz is greater than 25 [mu] m.

Description

Technical Field

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

[0002] Golf club heads are made of various materials. Composite club heads made of two or more materials are also known. A material corresponding to the required performance of the club head can be used.

[0003] Japanese Patent Gazette No. 4733336 discloses a golf club head comprising: a main body made of a titanium alloy, a striking plate made of a titanium alloy mounted on the main body, and a thin layer made of thermosetting polyurethane, which is arranged on the outer surface of the striking plate, has a thickness in the range of 0.127 to 2.540 mm, and has a plurality of scoring lines. Prior art literature Patent Literature Patent Document 1: Japanese Patent No. 4733336 Technical problem to be solved by the invention

[0005] As a basic performance of a club head, there is rebound performance. With high rebound performance, the flight distance can be increased. On the other hand, if the rebound performance is high, the ball tends to leave early and the bite feeling tends to deteriorate. The ball leaves the ball and the ball contacts the hitting surface. The bite feeling refers to the feeling that the ball does not slide on the hitting surface but sticks to the hitting surface during the shot. It is difficult to achieve both rebound performance and good bite feeling at the same time. Summary of the invention

[0006] An object of the present invention is to provide a golf club head that can achieve both good rebound performance and a good feel for the ball. Technical means for solving technical problems

[0007] In one embodiment, the present invention is a golf club head having a face portion forming a striking surface. In the club head, the face portion has a metal face portion and a polyurethane layer portion, the metal face portion is formed of metal, the polyurethane layer portion is provided outside the metal face portion and is formed of polyurethane, and the line roughness of the outer surface of the metal face portion in the portion covered by the polyurethane layer portion is: an arithmetic mean roughness Ra greater than 4.5 μm, or a maximum height Rz greater than 25 μm. Effects of the Invention

[0008] As a side aspect, it is possible to provide a golf club head that achieves both rebound performance and a good feel for the ball. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a plan view of the golf club head according to the first embodiment. Figure 2 yes Figure 1 An underside view of a golf club head. Figure 3 (a) is Figure 1 A front view of a golf club head, Figure 3 (b) is along Figure 3 (a) is a cross-sectional line of the outer surface of the club head along line E1. Figure 4 yes Figure 1 A perspective view of a golf club head. Figure 5 yes Figure 1 An exploded perspective view of a golf club head. Figure 6 It is along Figure 3 (a) is a cross-sectional view of the line AA. Figure 7 yes Figure 6 A partial enlarged view of . Figure 8 It is a plan view of a golf club head according to a second embodiment. Fig. 9 yes Figure 8 An underside view of a golf club head. Fig.10 yes Figure 8 Front view of a golf club head. Fig.11 yes Figure 8 A front view of a club head body in a golf club head. Fig.12 yes Figure 8 A perspective view of a golf club head. Fig.13 yes Figure 8 A perspective view of a club head body in a golf club head. Fig.14 yes Figure 8 An exploded perspective view of a golf club head. Fig.15 It is along Fig.10 Cross-sectional view along line AA. Fig.16 yes Fig.15 A partial enlarged view of . Fig.17 It is a plan view of a golf club head according to a third embodiment. Fig.18 yes Fig.17 An underside view of a golf club head. Fig.19 yes Fig.17 Front view of a golf club head. Fig. 20 yes Fig.17 A front view of a club head body in a golf club head. Fig.21 yes Fig.17 A perspective view of a golf club head. Fig. 22 yes Fig.17 A perspective view of a club head body in a golf club head. Fig.23 yes Fig.17 An exploded perspective view of a golf club head. Fig.24 It is along Fig.19 Cross-sectional view along line AA. Fig.25 yes Fig.24 A partial enlarged view of . Fig.26 (a) is a front view of a club head body of a modified example, Fig.26 (b) is a front view of a club head body of another modified example. Fig.26 (c) is a front view of a club head body of another modified example. Fig.26 (d) is a front view of a club head body of another modified example. Fig.26 (e) is a front view of a club head body according to another modified example. Fig. 27 (a) is a cross-sectional view of a golf club head according to another modified example. Fig. 27 (b) is a cross-sectional view of a golf club head according to another modified example. Fig. 27 (c) is a cross-sectional view of a golf club head according to another modified example. Fig.28 This is a conceptual diagram for explaining the reference state. Explanation of symbols 100, 200, 300, 400, 500, 600, 700, 800… golf club heads 100a, 200a, 300a, 400a, 500a, 600a, 700a, 800a…club head body 102, 202, 302…Club Face 102a, 202a, 302a… striking surface 102b, 202b, 302b…Inner surface of the club face 104, 204, 304…crown 106, 206, 306… bottom 108, 208, 308…Hose 120, 220, 320… The outer surface of the metal rod face 124, 224, 324…Inner surface of the polyurethane layer 126, 226, 326 ... Outer surface of the polyurethane layer 130 ... recessed portion for arranging the polyurethane layer portion 232…Edge of polyurethane layer 234…Edge fixing part 328…Slot 330…Edge of polyurethane layer 334…Edge fixing part 750…Inner surface convex part s4, s5, s6, s7, s8...Metal slot g7…polyurethane tank k1…Contour of the polyurethane layer k2, k3…Boundaries between the polyurethane layer and the head body Fc…Center of the clubface U1, U2, U3…Polyurethane layer M1, M2, M3…Metal rod face. DETAILED DESCRIPTION

[0010] Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

[0011] In this application, a reference state, a reference vertical plane, a toe-heel direction, a face-back direction, an up-down direction, a face center, a longitudinal section, a cross section, and a front view are defined.

[0012] The state in which the club head is placed on the ground plane HP at a predetermined club head angle is the reference state. Fig.28 As shown, in this reference state, the shaft axis Z is included in the plane VP perpendicular to the ground plane HP. The shaft axis Z is the center line of the shaft. Usually, the shaft axis Z coincides with the center line of the bolt hole of the head. The above plane VP is set as a reference vertical plane. The specified head tilt angle is published in the product catalog, for example.

[0013] There is known a golf club that can adjust the face angle, head angle and face angle according to the rotation position of the sleeve provided at the top end of the shaft. In this golf club, the sleeve can be removably fixed to the club head by a fixing member such as a screw. Therefore, in this golf club, the shaft can be loaded and unloaded relative to the club head. In the golf club having such a loading and unloading mechanism, in the above-mentioned reference state, all adjustment items are set to the middle value. The middle value represents the center of the adjustment width. The golf club having the club head of the present invention can also have such a loading and unloading mechanism.

[0014] In this reference state, the face angle is 0 degrees. That is, in a top view from above, the normal line in the face center of the striking surface is perpendicular to the toe-heel direction. The definitions of the face center and the toe-heel direction are described below.

[0015] In this specification, the toe-heel direction is the direction of the intersection line NL of the reference vertical plane VP and the ground plane HP (refer to Fig.28 ). The toe side in the toe-heel direction is also referred to simply as the "toe side". The heel side in the toe-heel direction is also referred to simply as the "heel side".

[0016] In this specification, the face-back direction is a direction perpendicular to the toe-heel direction and parallel to the ground plane HP. The face side in the face-back direction is also simply referred to as the "face side". The back side in the face-back direction is also simply referred to as the "back side".

[0017] In this specification, the up-down direction is a direction perpendicular to the toe-heel direction and perpendicular to the face-back direction. In other words, in this specification, the up-down direction is a direction perpendicular to the ground plane HP. The upper side in the up-down direction is also referred to as the "crown side". The lower side in the up-down direction is also referred to as the "sole side".

[0018] In this specification, the center of the club face is determined as follows. First, select an arbitrary point Pr near the approximate center of the striking surface in the up-down direction and the toe-heel direction. Next, determine a plane that passes through the point Pr, extends in the normal direction of the striking surface at the point Pr and is parallel to the toe-heel direction. Draw the intersection line of the plane and the striking surface, and determine the midpoint Px. Next, determine a plane that passes through the midpoint Px, extends in the normal direction of the striking surface at the point Px and is parallel to the up-down direction. Draw the intersection line of the plane and the striking surface, and determine the midpoint Py. Next, determine a plane that passes through the midpoint Py, extends in the normal direction of the striking surface at the point Py and is parallel to the toe-heel direction. Draw the intersection line of the plane and the striking surface, and redetermine the midpoint Px. Next, determine a plane that passes through the new midpoint Px, extends in the normal direction of the striking surface at the point Px and is parallel to the up-down direction. Draw the intersection line between the plane and the striking surface, and determine the midpoint Py again. Repeat this process to determine Px and Py in sequence. During the repetition of this process, the new position Py (the final position Py) when the distance between the new midpoint Py and the previous midpoint Py becomes less than 0.5 mm for the first time is the center of the club face.

[0019] In this specification, a longitudinal section refers to a section based on a plane perpendicular to the toe-heel direction. In this specification, a cross section refers to a section based on a plane perpendicular to the up-down direction. In other words, in this specification, a cross section refers to a section based on a plane parallel to the ground plane HP.

[0020] In this specification, the front view refers to a vertical projection of the club head obtained by taking the normal line at the center of the club face as the projection direction. In addition, unless otherwise specified, the shape, area, size, etc. of each area of ​​the club face are determined in the front view of the club face. The drawings based on the front view are also referred to as the front view in this specification.

[0021] The top view of the club head 100 is a projection image obtained by projecting the club head in a reference state onto a plane parallel to the ground plane HP. In this specification, the top view of the club head is also referred to as a top view.

[0022] Figure 1 is a top view of the golf club head 100 according to the first embodiment. Figure 2 is a bottom view of the club head 100. Figure 3 (a) is a front view of the club head 100, Figure 3 (b) is based on Figure 3 The cross-sectional line of the outer surface of the club head of the cross-sectional E1 of (a), Figure 4 is a perspective view of the club head 100. Figure 5 is an exploded perspective view of the club head 100. Figure 6 It is along Figure 3 (a) is a cross-sectional view of the AA line, Figure 7 yes Figure 6 A partial enlarged view of .

[0023] like Figure 1 to Figure 7 As shown, the club head 100 includes a face portion 102 , a crown portion 104 , a sole portion 106 , and a hosel portion 108 .

[0024] The club head 100 may be a wood type. The club head 100 may be a hybrid type. The club head 100 may be an iron type. The club head 100 may be a putter type. In this embodiment, the club head 100 is a wood type. The club head 100 is a driver club head. Figure 6 As shown, the club head 100 has a hollow structure. The club head 100 has a hollow portion h.

[0025] like Figure 6 As shown, the face portion 102 is formed with a striking face 102a and a face inner surface 102b. The striking face 102a contacts a golf ball when hitting. The striking face 102a is the outer surface of the face portion 102. The striking face 102a is also referred to as simply the face portion. The face inner surface 102b is the inner surface of the face portion 102. The face inner surface 102b faces the hollow portion h.

[0026] The crown 104 constitutes the upper surface of the club head 100. The crown 104 forms a crown outer surface 104a and a crown inner surface 104b. The crown inner surface 104b faces the hollow portion h.

[0027] The sole 106 constitutes the lower surface of the club head 100. The sole 106 forms a sole outer surface 106a and a sole inner surface 106b. The sole inner surface 106b faces the hollow portion h.

[0028] The hosel 108 is provided on the heel side of the club head 100. The hosel 108 has a head bolt hole 108a. A shaft (not shown) can be inserted into the head bolt hole 108a. Alternatively, a sleeve (not shown) attached to the tip of the shaft can be inserted into the head bolt hole 108a.

[0029] like Figure 3 As shown in (a) of FIG. 1 , the striking surface 102a has the face center Fc defined as described above.

[0030] The periphery of the striking surface 102a can be defined as follows. Figure 3 As shown in (a) of FIG. 1 , there are a plurality of planes E1, E2, E3, ... including the normal line of the striking surface 102a at the face center Fc. Figure 3 (b) represents a cross-sectional line of the outer surface of the club head based on the plane E1. In the cross-sectional area formed by these planes E1 and the like, a point Q1 is determined where the radius of curvature r of the cross-sectional line of the outer surface of the club head becomes 200 mm for the first time from the club face center Fc side toward the outside of the striking surface 102a. The set of points Q1 can be regarded as the periphery of the striking surface 102a.

[0031] like Figure 1 As shown, the crown 104 has a crown protrusion 110. The crown protrusion 110 is a protrusion formed on the crown outer surface 104a. Although not shown, the crown protrusion 110 is a hollow protrusion. Although not shown, a concave portion is formed on the inner surface of the crown protrusion 110. The crown protrusion 110 can affect the performance of the club head 100. For example, the crown protrusion 110 can affect the aerodynamic characteristics of the club head 100.

[0032] In the same toe-heel direction range as the ball hitting area, 45-degree boundary lines are set on the crown side and the sole side. Figure 6 As shown, the plane tangent to the striking surface 102a at the center Fc of the club face is set as the reference plane S1. In the longitudinal section, the tangent point P1 between the straight line L1 at 45 degrees relative to the reference plane S1 and the outer surface of the club head is determined. The tangent point P1 can be used as the outer edge point of the striking area in the longitudinal section. The longitudinal section can be set at each position in the toe-heel direction, and the tangent point P1 can be determined in each longitudinal section. The set of these tangent points P1 is used as a 45-degree boundary line. The striking area refers to a strip-shaped area centered on the center line passing through the center Fc of the club face and extending in the up and down direction, and its toe-heel width is 1.68 inches (42.67mm). The striking area is judged in the front view.

[0033] like Figure 7As shown, the club head 100 has a polyurethane layer portion U1. The polyurethane layer portion U1 is provided on the face portion 102. The club head 100 is composed of a club head body 100a and the polyurethane layer portion U1. The material of the club head body 100a is metal (titanium alloy). The material of the club head body 100a is not limited. The club head body 100a can be composed of multiple materials. The club head body 100a can also be composed of multiple parts.

[0034] like Figure 7 As shown, the face portion 102 includes a metal face portion M1 formed of metal and a polyurethane layer portion U1 provided outside the metal face portion M1. The polyurethane layer portion U1 is formed of polyurethane.

[0035] The metal face portion M1 has an outer surface 120 and an inner surface 122. The metal face portion M1 is a part of the club head body 100a. The inner surface 122 of the metal face portion M1 faces the hollow portion h. The inner surface 122 constitutes the club face inner surface 102b. A polyurethane layer portion U1 is provided on the outer surface 120 of the metal face portion M1. An inner surface 124 of the polyurethane layer portion U1 is in contact with the outer surface 120. Other layers may be sandwiched between the outer surface 120 and the polyurethane layer portion U1. An outer surface 126 of the polyurethane layer portion U1 is the striking surface 102a. The metal face portion M1 supports the polyurethane layer portion U1 from the inner side of the club head 100.

[0036] In addition, the metal face portion M1 may be a layered component that is not part of the head body 100a. For example, the metal face portion M1 may be disposed between the polyurethane layer portion U1 and the head body 100a. In this case, the head body 100a located inside the metal face portion M1 may be formed of a metal different from the metal face portion M1, or may be formed of a non-metal (carbon fiber reinforced plastic, etc.).

[0037] The outer surface 120 of the metal face portion M1 has a portion covered by the polyurethane layer portion U1 and a portion not covered by the polyurethane layer portion U1 and exposed to the outside. In the portion exposed to the outside, the metal face portion M1 constitutes the striking surface 102a. In the portion covered by the polyurethane layer portion U1, the metal face portion M1 does not constitute the striking surface 102a, and the polyurethane layer portion U1 constitutes the striking surface 102a. In addition, the entire outer surface 120 of the metal face portion M1 may be covered by the polyurethane layer portion U1. The polyurethane layer portion U1 may also constitute the entire striking surface 102a.

[0038] The head body 100a has a recess 130 for arranging the polyurethane layer U1. The polyurethane layer U1 is arranged in the recess 130. The recess 130 is formed on the outer surface 120 of the metal face portion M1. The contour line 130a of the recess 130 coincides with the contour line k1 of the polyurethane layer U1 (see Figure 3(a)). The depth of the recess 130 corresponds to the thickness of the polyurethane layer U1. The height of the recess 130 in the contour line 130a is consistent with the thickness t of the polyurethane layer U1 in the contour line k1. The bottom surface 130b of the recess 130 is formed by the metal rod face M1. The bottom surface 130b of the recess 130 is the outer surface 120 of the metal rod face M1. The bottom surface 130b of the recess 130 is covered by the polyurethane layer U1. Due to the presence of the recess 130, the striking surface 102a has substantially no step (surface step) in the contour line k1 of the polyurethane layer. In the case where the contour line k1 is located within the striking surface 102a, the height of the surface step in the contour line k1 can be set to be less than 0.1 mm.

[0039] In the present embodiment, the entire polyurethane layer portion U1 belongs to the face portion 102. The entire polyurethane layer portion U1 is contained within the striking surface 102a. The polyurethane layer portion U1 forms a portion of the striking surface 102a. The striking surface 102a includes a portion formed by the polyurethane layer portion U1 and a portion formed by the metal face portion M1. The portion formed by the metal face portion M1 constitutes a metal striking surface 102c formed by metal. The polyurethane layer portion U1 is surrounded by the metal striking surface 102c. The polyurethane layer portion U1 may form the entire striking surface 102a. The contour line k1 of the polyurethane layer portion U1 may coincide with the contour line of the striking surface 102a.

[0040] In the portion covered by the polyurethane layer U1 , the line roughness of the outer surface 120 of the metal face portion M1 satisfies the following (a) and / or (b). In the present embodiment, the bottom surface 130b of the recess 130 satisfies the following (a) and / or (b). (a) The arithmetic mean roughness Ra is greater than 4.5 μm. (b) The maximum height Rz is greater than 25 μm.

[0041] The arithmetic mean roughness Ra and the maximum height Rz are defined by JIS B 0601:2013, respectively, and are measured based on the same JIS regulations and JIS B 0633:2001. These values ​​can be measured by a contact or non-contact surface roughness measuring device. For example, these values ​​can be measured using a 3D shape dimension measuring device VR-5200 produced by KEYENCE CORPORATION under the following measurement conditions. In addition, when multiple measurement values ​​are obtained in the measurement area, the maximum value can be used. Determination conditions: Cut-off value (λc): 0.8mm / 2.5mm / 8mm Filter type: Gaussian λs value: None 3D measurement settings: High precision (roughness)

[0042] The arithmetic mean roughness Ra and the maximum height Rz are set in the portion constituting the interface with the polyurethane layer portion U1. Fig.26 In the case of the metal grooves described in (a) to (e), the portion where the metal grooves are formed is not the object for setting the arithmetic mean roughness Ra and the maximum height Rz. The arithmetic mean roughness Ra and the maximum height Rz are set for the portion where the metal grooves are not formed.

[0043] In the portion covered by the polyurethane layer portion U1 , the outer surface 120 of the metal face portion M1 satisfies the following (c). (c) The developed area ratio Sdr is 0.12 or more.

[0044] The developed area ratio Sdr is set in the portion constituting the interface with the polyurethane layer portion U1. When the outer surface 120 of the metal face portion M1 has a metal groove described below, the portion where the metal groove is formed is not set for the developed area ratio Sdr.

[0045] The developed area ratio Sdr is defined by ISO25178 and is measured based on the same ISO regulations. The developed area ratio Sdr can be measured, for example, using a non-contact measuring device. The developed area ratio Sdr can be measured, for example, using a 3D shape dimension measuring device VR-5200 produced by Keyence Corporation under the following measuring conditions. In addition, when multiple measured values ​​are obtained in the measuring area, the maximum value can be used. Measurement conditions Size: 10000μm×10000μm Filter type: Gaussian Other filters: None Terminal effect correction: On

[0046] The outer surface 120 of the metal face portion M1 may also include fine irregularities with a height of 100 nanometers or less in the portion covered by the polyurethane layer portion U1. The height is the difference between the heights of adjacent peaks and valleys. A primer and / or adhesive is provided between the metal face portion M1 and the polyurethane layer portion U1.

[0047] Figure 8 is a top view of a golf club head 200 according to the second embodiment. Fig. 9 is a bottom view of the club head 200. Fig.10 is a front view of the club head 200, Fig.11 2 is a front view showing a state where the polyurethane layer portion U2 is removed from the club head 200. Fig.12 is a three-dimensional diagram of the club head 200. Fig.13 2 is a perspective view showing a state where the polyurethane layer portion U2 is removed from the club head 200. Fig.14 is an exploded perspective view of the club head 200. Fig.15 It is along Fig.10 The cross-sectional view of line AA, Fig.16 yes Fig.15 A partial enlarged view of .

[0048] like Figures 8 to 16 As shown in FIG. 2 , the club head 200 includes a club face 202, a crown 204, a sole 206, and a hosel 208. The club head 200 is a wood type. Fig.15 As shown, the club head 200 has a hollow structure. The club head 200 has a hollow portion h.

[0049] like Fig.15 As shown in FIG. 1 , the face portion 202 is formed with a striking surface 202a and a face inner surface 202b. The striking surface 202a is a surface that contacts a golf ball when hitting. The striking surface 202a is an outer surface of the face portion 202. The face inner surface 202b is an inner surface of the face portion 202. The face inner surface 202b faces the hollow portion h. Fig.10 As shown in FIG. 2 , the striking surface 202 a has the face center Fc defined as described above.

[0050] like Fig.15 As shown, the crown 204 constitutes the upper surface of the club head 200. The crown 204 forms a crown outer surface 204a and a crown inner surface 204b. The crown inner surface 204b faces the hollow portion h. The crown 204 has a crown convex portion 210. The bottom 206 constitutes the lower surface of the club head 200. The bottom 206 forms a bottom outer surface 206a and a bottom inner surface 206b. The bottom inner surface 206b faces the hollow portion h. The neck portion 208 is arranged on the heel side of the club head 200. The neck portion 208 has a club head bolt hole 208a.

[0051] like Fig.14 and Fig.16 As shown, the club head 200 has a polyurethane layer portion U2. The polyurethane layer portion U2 is provided on the club face portion 202. The polyurethane layer portion U2 forms the entirety of the striking surface 202a. The polyurethane layer portion U2 extends to the outside of the striking surface 202a. The polyurethane layer portion U2 extends to the 45-degree boundary line L2 (refer to Figure 6 ) on the back side.

[0052] The club head 200 is composed of a club head body 200a and a polyurethane layer portion 122. The material of the club head body 200a is metal (titanium alloy). Fig.14As shown, the head body 200a is composed of a plurality of parts. The head body 200a is composed of a face part 200b and a back part 200c. The back part 200c is joined to the back side of the face part 200b. The face part 200b has a portion constituting a face part 202. The back part 200c has a portion constituting a crown part 204 and a portion constituting a sole part 206. The back part 200c is a member having an opening 203 on the face side (see Fig.14 The opening 203 is closed by the face member 200 b. The face member 200 b and the back member 200 c are joined at a boundary 201 by welding. The boundary 201 is located at the outline of the opening 203.

[0053] like Fig.14 and Fig.16 As shown, the face portion 202 includes a metal face portion M2 formed of metal and a polyurethane layer portion U2 provided outside the metal face portion M2. The polyurethane layer portion U2 is formed of polyurethane.

[0054] At least a part of the metal face portion M2 is constituted by the face member 200b. In the present embodiment, the entire metal face portion M2 is constituted by the face member 200b.

[0055] The metal face portion M2 has an outer surface 220 and an inner surface 222. The inner surface 222 of the metal face portion M2 faces the hollow portion h. The inner surface 222 constitutes the face inner surface 202b. The outer surface 220 of the metal face portion M2 is provided with a polyurethane layer portion U2. The inner surface 224 of the polyurethane layer portion U2 is in contact with the outer surface 220. Other layers may be sandwiched between the outer surface 220 and the polyurethane layer portion U2. The outer surface 226 of the polyurethane layer portion U2 forms the striking surface 202a. The metal face portion M2 supports the polyurethane layer portion U2 from the inner side of the club head 200.

[0056] In the aforementioned club head 100, a portion of the outer surface 120 of the metal club face portion M1 is covered by the polyurethane layer portion U1. In contrast, in the club head 200, the entire outer surface 220 of the metal club face portion M2 is covered by the polyurethane layer portion U2. In the completed club head 200, the metal club face portion M2 cannot be seen from the outside. The boundary 201 between the club face component 200b and the back component 200c is also covered by the polyurethane layer portion U2. The polyurethane layer portion U2 extends to the outside of the striking surface 202a. The polyurethane layer portion U2 extends to the 45-degree boundary line L2 (refer to Figure 6 ). The polyurethane layer portion U2 extends to the crown 204. The polyurethane layer portion U2 extends to the back side of the 45-degree boundary line L2 on the crown side. The polyurethane layer portion U2 extends to the bottom 206. The polyurethane layer portion U2 extends to the back side of the 45-degree boundary line L2 on the bottom side.

[0057] The back part 200c has a step portion 228. The step portion 228 is arranged at a position corresponding to the rear edge 230 of the polyurethane layer portion U2. The step portion 228 is arranged on the crown 204. The step portion 228 is arranged on the bottom 206. The height of the step portion 228 corresponds to the thickness of the polyurethane layer portion U2 at the rear edge 230. In the boundary k2 between the polyurethane layer portion U2 and the back part 200c (the club head body 200a), the step (surface step) in the outer surface of the club head does not substantially exist. In the present embodiment, the boundary k2 is located outside the striking surface 202a. The surface step in the boundary k2 can be less than 2 mm, further can be less than 1 mm, and further can be less than 0.5 mm.

[0058] In the present embodiment, a part of the polyurethane layer portion U2 belongs to the face portion 202. The polyurethane layer portion U2 forms the entirety of the striking surface 202a. Furthermore, the polyurethane layer portion U2 extends to the outside of the boundary line of the striking surface 202a. The polyurethane layer portion U2 extends to the crown 204. The polyurethane layer portion U2 forms a part of the crown outer surface 204a. The polyurethane layer portion U2 extends to the sole 206. The polyurethane layer portion U2 forms a part of the sole outer surface 206a.

[0059] like Fig.16 As shown, in the club head 200 of the second embodiment, the polyurethane layer portion U2 extends to the outside of the striking surface 202a. The polyurethane layer portion U2 extends to the 45-degree boundary line L2 (see Figure 6 ) on the back side of the 45-degree boundary line L2. The club head body 200a has an edge fixing portion 234 fixing the edge 232 of the polyurethane layer portion 112 on the back side of the 45-degree boundary line L2. The edge fixing portion 234 is located outside the striking surface 202a. The edge fixing portion 234 is composed of the step portion 228 and the outer surface of the club head body 200a near the step portion 228. The edge fixing portion 234 fixes the edge 232 of the polyurethane layer portion 112 by bonding.

[0060] In the portion covered by the polyurethane layer portion U2 , the linear roughness of the outer surface 220 of the metal face portion M2 satisfies the following (a) and / or (b). (a) The arithmetic mean roughness Ra is greater than 4.5 μm. (b) The maximum height Rz is greater than 25 μm.

[0061] In the portion covered by the polyurethane layer portion U2, the outer surface 220 of the metal face portion M2 satisfies the following (c). (c) The developed area ratio Sdr is 0.12 or more.

[0062] The outer surface 220 of the metal face portion M2 includes fine irregularities with a height of 100 nanometers or less in the portion covered by the polyurethane layer portion U2. A primer and / or an adhesive is provided between the metal face portion M2 and the polyurethane layer portion U2.

[0063] Fig.17 is a top view of a golf club head 300 according to a third embodiment. Fig.18 is a bottom view of the club head 300. Fig.19 is a front view of the club head 300, Fig. 20 2 is a front view showing a state where the polyurethane layer portion U3 is removed from the club head 300. Fig.21 is a three-dimensional diagram of the club head 300. Fig. 22 2 is a perspective view showing a state where the polyurethane layer portion U3 is removed from the club head 300. Fig.23 is an exploded perspective view of the club head 300. Fig.24 It is along Fig.19 The cross-sectional view of line AA, Fig.25 yes Fig.24 A partial enlarged view of .

[0064] like Figures 17 to 25 As shown, the club head 300 has a club face 302, a crown 304, a sole 306, and a hosel 308. The club head 300 is a wood type. Fig.24 As shown, the club head 300 has a hollow structure. The club head 300 has a hollow portion h.

[0065] like Fig.24 As shown in FIG. 1 , the face portion 302 is formed with a striking surface 302a and a face inner surface 302b. The striking surface 302a is the surface that contacts the golf ball when hitting. The striking surface 302a is the outer surface of the face portion 302. The face inner surface 302b is the inner surface of the face portion 302. The face inner surface 302b faces the hollow portion h. Fig.19 As shown, the striking face 302a has the face center Fc defined as described above.

[0066] The crown 304 constitutes the upper surface of the club head 300. The crown 304 forms a crown outer surface 304a and a crown inner surface 304b. The crown inner surface 304b faces the hollow portion h. The crown 304 has a crown convex portion 310. The sole 306 constitutes the lower surface of the club head 300. The sole 306 forms a sole outer surface 306a and a sole inner surface 306b. The sole inner surface 306b faces the hollow portion h. The hosel 308 is provided on the heel side of the club head 300. The hosel 308 has a club head bolt hole 308a.

[0067] like Fig.23 and Fig.25As shown, the club head 300 has a polyurethane layer U3. The polyurethane layer U3 is provided on the club face portion 302. The polyurethane layer U3 forms the entirety of the striking surface 302a. The polyurethane layer U3 extends to the outside of the striking surface 302a. The polyurethane layer U3 extends to the 45-degree boundary line L2 (refer to Figure 6 ) on the back side.

[0068] The club head 300 is composed of a club head body 300a and a polyurethane layer portion 113. The material of the club head body 300a is metal (titanium alloy). Fig.23 As shown, the head body 300a is composed of a plurality of parts. The head body 300a is composed of a face part 300b and a back part 300c. The back part 300c is joined to the back side of the face part 300b. The face part 300b has a portion constituting a face part 302. The back part 300c has a portion constituting a crown part 304 and a portion constituting a sole part 306. The back part 300c is a member having an opening 303 on the face side, and the opening 303 is closed by the face part 300b. A boundary 301 (see FIG. 1 ) between the face part 300b and the back part 300c is formed. Fig. 22 ) are joined by welding.

[0069] like Fig.25 As shown, the face portion 302 includes a metal face portion M3 formed of metal and a polyurethane layer portion U3 provided outside the metal face portion M3. The polyurethane layer portion U3 is formed of polyurethane.

[0070] At least a part of the metal face portion M3 is constituted by the face member 300b. In the present embodiment, the entire metal face portion M3 is constituted by the face member 300b.

[0071] The metal face portion M3 has an outer surface 320 and an inner surface 322. The inner surface 322 of the metal face portion M3 faces the hollow portion h. The inner surface 322 constitutes the face inner surface 302b. The outer surface 320 of the metal face portion M3 is provided with a polyurethane layer portion U3. The inner surface 324 of the polyurethane layer portion U3 is in contact with the outer surface 320. Other layers may be sandwiched between the outer surface 320 and the polyurethane layer portion U3. The outer surface 326 of the polyurethane layer portion U3 is the striking surface 302a. The metal face portion M3 supports the polyurethane layer portion U3 from the inner side of the club head 300.

[0072] In the club head 300, the entire outer surface 320 of the metal face portion M3 is covered by the polyurethane layer portion U3. In the completed club head 300, the metal face portion M3 cannot be seen from the outside. The boundary 301 between the face component 300b and the back component 300c is also covered by the polyurethane layer portion U3. The polyurethane layer portion U3 extends to the outside of the striking surface 302a. The polyurethane layer portion U3 extends to the 45-degree boundary line L2 (refer to FIG. 1 ). Figure 6). The polyurethane layer portion U3 extends to the crown 304. The polyurethane layer portion U3 extends to the back side of the 45-degree boundary line L2 on the crown side. The polyurethane layer portion U3 extends to the bottom 306. The polyurethane layer portion U3 extends to the back side of the 45-degree boundary line L2 on the bottom side.

[0073] like Fig.25 As shown, the club head body 300a has a groove 328. The groove 328 is provided on the outer side of the striking surface 302a. The groove 328 is provided on the back part 300c. The groove 328 is provided at a position corresponding to the edge (rear edge) 330 of the polyurethane layer part U3. The groove 328 is provided on the crown 304. The groove 328 is provided on the bottom 306. The edge 330 of the polyurethane layer part U3 is bent in a direction toward the inner side of the club head 300. The extension direction of the edge 330 is consistent with the depth direction of the groove 328. The width of the groove 328 corresponds to the thickness of the edge 330. The edge 330 enters the groove 328. The groove 328 is filled with the edge 330.

[0074] In the boundary k3 between the polyurethane layer portion 110 and the back member 300c (the club head body 300a), the step (surface step) in the outer surface of the club head does not substantially exist. The boundary k3 is located outside the striking surface 302a. The surface step in the boundary k3 can be less than 2 mm, further can be less than 1 mm, and further can be less than 0.5 mm.

[0075] In this embodiment, a part of the polyurethane layer portion U3 belongs to the face portion 302. The polyurethane layer portion U3 forms the entirety of the striking surface 302a. The polyurethane layer portion U3 extends to the crown 304. The polyurethane layer portion U3 forms a part of the crown outer surface 304a. The polyurethane layer portion U3 extends to the sole 306. The polyurethane layer portion U3 forms a part of the sole outer surface 306a.

[0076] like Fig.25 As shown, in the club head 300 of the third embodiment, the polyurethane layer U3 also extends to the outside of the striking surface 302a. The polyurethane layer U3 extends to the 45-degree boundary line L2 (see Figure 6) on the back side of the 45-degree boundary line L2. The head body 300a has an edge fixing portion 334 that fixes the edge 330 of the polyurethane layer portion U3 on the back side of the 45-degree boundary line L2. The edge fixing portion 334 is located on the outside of the striking surface 302a. In the present embodiment, the edge fixing portion 334 is a groove 328. The edge fixing portion 334 is provided on the crown 304. The edge fixing portion 334 is provided on the bottom 306. The groove 328 (edge ​​fixing portion 334) physically stops the edge 330. Moreover, the edge 330 is fixed to the groove 328 (edge ​​fixing portion 334) by bonding. The thickness t of the polyurethane layer portion U3 in the area of ​​the striking surface 302a is less than the thickness t of the polyurethane layer portion U3 in the edge 330. That is, the thickness t of the polyurethane layer portion U3 in the edge 330 is greater than the thickness t of the polyurethane layer portion U3 in the area of ​​the striking surface 302a. The thickness t is measured along the normal direction of the outer surface of the head 300. The layer thickness v of the polyurethane layer portion U3 in the edge portion 330 is greater than the layer thickness v of the polyurethane layer portion U3 in the region of the striking surface 302a. The layer thickness v is measured along the direction in which the thickness becomes the smallest in the longitudinal section (refer to Fig.25 ).

[0077] In the portion covered by the polyurethane layer portion U3 , the linear roughness of the outer surface 320 of the metal face portion M3 satisfies the following (a) and / or (b). (a) The arithmetic mean roughness Ra is greater than 4.5 μm. (b) The maximum height Rz is greater than 25 μm.

[0078] In the portion covered by the polyurethane layer portion U3 , the outer surface 320 of the metal face portion M3 satisfies the following (c). (c) The developed area ratio Sdr is 0.12 or more.

[0079] The outer surface 320 of the metal face portion M3 may include fine irregularities with a height of 100 nanometers or less in the portion covered by the polyurethane layer portion U3. A primer and / or an adhesive is provided between the metal face portion M3 and the polyurethane layer portion U3.

[0080] Fig.26 (a) to (e) are front views of the club head body in the club head of the modified example. They show the club head in a state where the polyurethane layer portion is removed. The metal grooves in these modified examples can be applied to the club heads of the first embodiment to the third embodiment described above.

[0081] Fig.26 (a) is a front view of a club head body 400a in a club head 400 according to a modified example. Fig.26(a) is a front view of the state where the polyurethane layer portion is removed from the club head 400. The club head body 400a has a metal club face portion M4. In the portion covered by the polyurethane layer portion, the outer surface 420 of the metal club face portion M4 may also have one or more grooves. In the present embodiment, the outer surface 420 has a plurality of grooves s4. In order to distinguish from other grooves, in this specification, the groove s4 provided on the outer surface 420 of the metal club face portion M4 is also referred to as a metal groove. The metal groove s4 is covered by the polyurethane layer portion, and therefore cannot be seen from the outside in the club head 400. Of course, this is a case where the polyurethane layer portion is not transparent. The polyurethane layer portion may also have transparency. That is, the polyurethane layer portion may be transparent or translucent. In this case, the metal groove s4 can be seen from the outside.

[0082] The outer surface 420 of the metal face portion M4 has a central region 440 having no metal groove s4, a toe groove region 442 located on the toe side of the central region 440 and having the metal groove s4, and a heel groove region 444 located on the heel side of the central region 440 and having the metal groove s4. In the front view, the central region 440 includes the position of the face center Fc in the front view.

[0083] The metal face portion M4 has a striking face portion 446 covered by a portion constituting the striking face in the polyurethane layer portion. The central region 440, the toe groove region 442, and the heel groove region 444 are provided in the striking face portion 446. The central region 440 crosses the striking face portion 446 from the crown side to the sole side.

[0084] The metal grooves s4 extend in the longitudinal direction. The longitudinal direction may be a direction that forms an angle of ±20° or less with respect to the vertical direction in a front view. The metal grooves s4 extend in the longitudinal direction outside the ball hitting area. In the metal face portion M4, the density of the metal grooves s4 is higher outside the ball hitting area than inside the ball hitting area.

[0085] Fig.26 (b) is a front view of a club head body 500a in a club head 500 according to another modified example. Fig.26 (b) is a front view of the club head 500 with the polyurethane layer removed. The club head body 500a has a metal club face portion M5. In the portion covered by the polyurethane layer, the outer surface 520 of the metal club face portion M5 has a plurality of grooves (metal grooves) s5. The metal grooves s5 are covered by the polyurethane layer. In the case where the polyurethane layer is not transparent, the metal grooves s5 cannot be seen from the outside in the club head 500.

[0086] The outer surface 520 of the metal face portion M5 includes a central region 540 having no metal groove s5, a toe groove region 542 located on the toe side of the central region 540 and having the metal groove s5 arranged therein, a heel groove region 544 located on the heel side of the central region 540 and having the metal groove s5 arranged therein, an upper groove region 550 located on the upper side of the central region 540 and having the metal groove s5 arranged therein, and a lower groove region 552 located on the lower side of the central region 540 and having the metal groove s5 arranged therein. In the front view, the central region 540 includes the position of the face center Fc.

[0087] The metal face portion M5 has a striking face portion 546 covered by a portion constituting the striking face in the polyurethane layer portion. The striking face portion 546 includes a central region 540 , a toe groove region 542 , a heel groove region 544 , an upper groove region 550 , and a lower groove region 552 .

[0088] In the toe groove area 542 and the heel groove area 544, the metal groove s5 extends in the longitudinal direction. In the upper groove area 550 and the lower groove area 552, the metal groove s5 extends in the transverse direction. The transverse direction may be a direction that forms an angle of ±20° or less with respect to the toe-heel direction in a front view. The metal groove s5 is arranged in the longitudinal direction on the outside of the ball hitting area. The metal groove s5 is arranged in the transverse direction on the inside of the ball hitting area. The directions of the metal groove s5 are different on the inside and outside of the ball hitting area.

[0089] Fig.26 (c) is a front view of a club head body 600a in a club head 600 according to another modified example. Fig.26 (c) is a front view of the club head 600 with the polyurethane layer removed. The club head body 600a has a metal face portion M6. In the portion covered by the polyurethane layer, the outer surface 620 of the metal face portion M6 has a plurality of grooves (metal grooves) s6. The metal grooves s6 are covered by the polyurethane layer. In the case where the polyurethane layer is not transparent, the metal grooves s6 cannot be seen from the outside in the club head 600.

[0090] The outer surface 620 of the metal face portion 246 includes a central region 640 having no metal groove s6, a toe groove region 642 located on the toe side of the central region 640 and having the metal groove s6, and a heel groove region 644 located on the heel side of the central region 640 and having the metal groove s6. In front view, the central region 640 includes the center of the face.

[0091] The metal face portion M6 has a striking face portion 646 covered by a portion constituting the striking face in the polyurethane layer portion. The central region 640, the toe groove region 642, and the heel groove region 644 are provided in the striking face portion 646. The central region 640 crosses the striking face portion 646 from the crown side to the sole side.

[0092] In the toe groove region 642, the metal grooves s6 are curved and extend in a manner convex toward the toe side. In the heel groove region 644, the metal grooves s6 are curved and extend in a manner convex toward the heel side. In the metal face portion M6, the density of the metal grooves s6 is greater on the outside of the ball hitting region than on the inside of the ball hitting region.

[0093] Fig.26 (d) is a front view of a club head body 700a in a club head 700 according to another modification. Fig.26 (d) is a front view of the club head 700 with the polyurethane layer removed. The club head body 700a has a metal face portion M7. In the portion covered by the polyurethane layer, the outer surface 720 of the metal face portion M7 has a plurality of grooves (metal grooves) s7. The metal grooves s7 are covered by the polyurethane layer. In the case where the polyurethane layer is not transparent, the metal grooves s7 cannot be seen from the outside of the club head 700.

[0094] The outer surface 720 of the metal face portion 247 does not have a central region without the metal groove s7. The metal groove s7 is disposed on the entire outer surface 720. The metal face portion 247 has a striking face portion 746 covered by a portion constituting a striking face in the polyurethane layer portion. All the metal grooves s7 are disposed on the striking face portion 746. The metal grooves s7 extend in a lateral direction. The lateral direction may be a direction forming an angle of ±20° or less with respect to the toe-heel direction in a front view.

[0095] Fig.26 (e) is a front view of a club head body 800a in a club head 800 according to another modified example. Fig.26 (e) is a front view of the state where the polyurethane layer portion is removed from the club head 800. The club head body 800a has a metal club face portion M8. In the portion covered by the polyurethane layer portion, the outer surface 820 of the metal club face portion M8 has a plurality of grooves (metal grooves) s8. The metal grooves s8 are covered by the polyurethane layer portion. In the case where the polyurethane layer portion is not transparent, in the club head 800, the metal grooves s8 cannot be seen from the outside. The metal club face portion M7 has a striking face portion 846 covered by a portion constituting the striking face in the polyurethane layer portion. All the metal grooves s8 are arranged on the striking face portion 846. The metal grooves s8 extend along a circle centered on a predetermined point, respectively. The center point can be located at or near the club face center Fc. The position of the center point can be located within a circle of radius r centered on the club face center Fc in the front view, and the radius r can be 22 mm, further 16 mm, and further 10 mm.

[0096] The polyurethane layer portion may have one or more grooves on its outer surface. In order to distinguish it from other grooves, the groove is also called a polyurethane groove. The polyurethane groove is provided in the area constituting the striking surface. The polyurethane groove is a groove provided on the striking surface and can be a so-called surface groove (score line). In addition, in the following embodiments, although a polyurethane groove and a metal groove are provided, a polyurethane groove may be provided instead of a metal groove.

[0097] Fig. 27 (a) is a longitudinal sectional view of a modified example having a polyurethane groove. The club head of this modified example is a club head body 700a ( Fig.26 (d)) is formed by adding a polyurethane layer portion U7. The polyurethane layer portion U7 has a groove g7. The groove provided in the polyurethane layer portion U7 is also called a polyurethane groove. The polyurethane groove g7 is provided on the striking surface 702a. The polyurethane groove g7 extends in the above-mentioned lateral direction. The polyurethane groove g7 extends in parallel with the metal groove s7. A polyurethane groove g7 is provided between two adjacent metal grooves s7. The polyurethane groove g7 and the metal groove s7 are arranged alternately. The polyurethane groove g7 is provided at a position that does not overlap with the metal groove s7. The polyurethane groove g7 can be provided in accordance with the golf rules regarding the grooves in the hitting area.

[0098] The polyurethane layer portion U7 has a convex portion 750 on its inner surface 724. The convex portion 750 is also referred to as an inner surface convex portion. The inner surface 724 of the polyurethane layer portion U7 has an inner surface convex portion 750. The inner surface convex portion 750 enters the metal groove s7. The height of the inner surface convex portion 750 is consistent with the depth of the metal groove s7. The width of the inner surface convex portion 750 is consistent with the width of the metal groove s7. The inner surface convex portion 750 fills the metal groove s7. The inner surface convex portion 750 is set at a position that does not overlap with the metal groove s7. In addition, the inner surface convex portion 750 can be pre-formed in the polyurethane layer portion U7 and then inserted into the metal groove s7, or it can be formed by the metal groove s7.

[0099] Fig. 27 (b) is a longitudinal sectional view of another modified example. Fig. 27 The implementation method of (b) is Fig. 27 The difference between the embodiment (a) is only the depth of the metal groove s7 (and the height of the inner surface protrusion 750). In this embodiment, the depth of the metal groove s7 is different among the plurality of metal grooves s7. The closer the depth of the metal groove s7 is to the center Fc of the club face, the smaller it is. In other words, the farther the depth of the metal groove s7 is from the center Fc of the club face, the larger it is. This structure can be suitable for golfers of average level who often make off-center shots.

[0100] Fig. 27 (c) is a longitudinal sectional view of another modified example. Fig. 27 The implementation method of (c) is Fig. 27The difference between the embodiment (a) is only the depth of the metal groove s7 (and the height of the inner surface protrusion 750). In this embodiment, the depth of the metal groove s7 is different among the plurality of metal grooves s7. The closer the depth of the metal groove s7 is to the club face center Fc, the greater the depth. In other words, the farther the depth of the metal groove s7 is from the club face center Fc, the smaller the depth. This structure can be suitable for golfers such as advanced golfers and professional golfers who hit more near the club face center Fc.

[0101] Fig. 27 The implementation methods (a) to (c) are implemented by using Fig.26 (d) is a modified example of the club head body 700a, but the structure having the inner surface convex portion entering the metal groove can be applied to the club head body including Fig.26 Metal grooves of various structures including the respective embodiments (a) to (e).

[0102] The above-mentioned embodiments have the following effects.

[0103] By providing a metal club face, the structural part of the club head including the club face can be formed of metal, so the rebound performance can be improved. On the other hand, in a metal club head with high rebound performance, the ball leaves early or slips easily, so it is difficult to get a good bite feeling. That is, in this case, the ball tends to leave the hitting face early, and the ball tends to slide on the hitting face during hitting. As a result, operability is easily reduced. In addition, when the ball leaves early, the hitting feeling may feel harder. In addition, operability refers to the ability to consciously control the hitting performance. When the operability is poor, the probability of hitting with the desired trajectory will be reduced.

[0104] By providing a polyurethane layer on the metal shaft face, a club head with a metal structure having high rebound performance can have a good ball bite. By providing a polyurethane layer on the outside of the metal shaft face and increasing the surface roughness of the metal shaft face at the interface between the metal shaft face and the polyurethane layer, the ball bite can be improved. In addition, the ball bite is difficult to measure objectively, but golfers (especially advanced golfers and professional golfers) can recognize it as a hitting feeling.

[0105] During hitting, the polyurethane layer is easy to be in close contact with the shell of the ball which is also made of resin. Therefore, the sliding of the ball on the hitting surface during hitting is effectively suppressed. As a result, the ball bite feeling becomes stronger and the operability can be improved.

[0106] In addition, when the ball shell material is polyurethane, the close contact between the polyurethane layer and the ball shell is further improved, which can improve the ball bite feeling. In particular, advanced golfers and professional golfers tend to use balls with polyurethane shell materials.

[0107] By increasing the surface roughness of the metal shaft face, an anchoring effect is produced on the polyurethane layer, so that the polyurethane layer becomes less likely to slide relative to the metal shaft face during a shot, thereby improving the feel of the ball.

[0108] The anchoring effect based on the surface roughness of the metal shaft face can reach the ball through the polyurethane layer. The polyurethane layer is compressed by the strong pressing force during hitting the ball, and the unevenness of the metal surface can be reflected on the hitting surface. As a result, the bite feeling of the ball is further improved.

[0109] The anchoring effect based on the surface roughness of the metal rod face improves the fixation of the polyurethane layer to the metal rod face. Therefore, the polyurethane layer can be effectively prevented from sliding and falling off. By using an adhesive and / or a primer, the fixation of the polyurethane layer to the metal rod face can be further improved.

[0110] The surface roughness or developed area ratio of the metal rod face increases the surface area of ​​the metal rod face, and the bonding area increases. Therefore, the fixation of the polyurethane layer to the metal rod face is further improved. The surface area of ​​the metal rod face is further increased by the fine concavo-convex with a height of less than 100 nanometers, and the above fixation is further improved.

[0111] When the metal shaft face with high rebound performance contacts the ball, it is easy to feel a hard hitting feeling. The polyurethane layer portion disposed on the outer surface of the metal shaft face can provide a good hitting feeling.

[0112] In the club head 200 of the second embodiment, the polyurethane layer portion U2 extends to the outside of the striking surface 202a, and the edge 232 of the polyurethane layer portion U2 is fixed by the edge fixing portion 234 located outside the striking surface 202a. In this structure, as long as the ball collides with the striking surface 202a, the edge 232 will not collide with the ball. When the ball collides with the edge of the polyurethane layer portion U2, the polyurethane layer portion existing around the striking point is insufficient, and the fixing strength relative to the shear force is reduced. Since the edge 232 is located outside the striking surface 202a, it is difficult for the ball to collide, and it is difficult for the fixing strength to be insufficient. As a result, the fixing strength of the polyurethane layer portion U2 is improved.

[0113] In the club head 300 of the third embodiment, the edge fixing portion 334 provided on the outer side of the striking surface 302a is the groove 328. By inserting the edge 330 into the groove 328, the edge 330 is physically locked. In this embodiment, the effect of the edge fixing portion 334 disposed on the outer side of the striking surface 302a is further improved. In addition, the edge fixing portion 334 may also sandwich the edge 330. For example, the edge 330 may be compressed by the groove 328 and inserted into the groove 328.

[0114] like Fig.26As shown in (a) to (e) of FIG. 8 , metal grooves are provided in the club heads 400 to 800. These metal grooves suppress the sliding of the polyurethane layer relative to the metal club face portion through their edge effect. Moreover, the edge effect of the metal grooves can reach the ball through the polyurethane layer. The polyurethane layer is compressed by the strong pressing force during hitting the ball, and the edge effect of the metal grooves can be reflected on the hitting surface. As a result, the bite feeling of the ball can be further improved.

[0115] like Fig.26 As shown in (a) to (e) of FIG. 4 , metal grooves s4 to s8 are provided in the club heads 400 to 800. These metal grooves suppress the sliding of the polyurethane layer relative to the metal club face by their edge effect. The polyurethane layer is compressed by the strong pressing force when hitting the ball, and is embedded in the metal groove. Therefore, the above-mentioned edge effect is improved. The fixing strength of the polyurethane layer against the shear force is improved by the metal groove.

[0116] like Fig.26 As in the embodiments (a), (b) and (c) of the present invention, the metal grooves can be selectively (or at a high density) arranged on the peripheral side of the striking surface. As described above, when the ball collides with the edge of the polyurethane layer, the fixing strength against the shear force is likely to be insufficient. The metal grooves arranged on the peripheral side can effectively improve the fixing strength when the ball collides with the edge of the polyurethane layer. In addition, as Fig.26 As shown in (a) to (e) of FIG. 1 , the direction of the metal groove can be arranged to be substantially perpendicular to the direction of the shear force caused by the impact. This structure can improve the fixing strength against the shear force.

[0117] like Fig. 27 As shown in (a) to (c), when the inner surface protrusion 750 that enters the metal groove s7 is provided, the inner surface protrusion 750 engages with the metal groove s7, so the fixing strength against the shear force is further improved. In addition, by setting the polyurethane groove g7 at a position that does not overlap with the metal groove s7, the function of the polyurethane groove g7 as a surface groove is suppressed from being reduced. Fig. 27 As shown in (b), the metal groove s7 may become deeper as it moves away from the club face center Fc. In this case, the fixing strength on the peripheral side of the striking face can be effectively improved. Fig. 27 As shown in (c), the metal groove s7 may become deeper as it approaches the face center Fc. In this case, the fixing strength at the face center Fc where the hitting frequency is high can be effectively improved.

[0118] From the perspective of the ball biting feeling, the arithmetic mean roughness Ra of the outer surface of the metal rod face in the portion covered by the polyurethane layer is preferably greater than 4.5 μm, more preferably greater than 7 μm, and more preferably greater than 10 μm. From the perspective of the fixing strength, the arithmetic mean roughness Ra is also preferably larger. When the arithmetic mean roughness Ra is too large, the concavity and convexity of the metal rod face will be reflected excessively to the hitting surface through the polyurethane layer. In this case, the contact relationship between the concavity and the spherical dimple of the ball will affect the movement of the ball. From this perspective, the arithmetic mean roughness Ra is preferably less than 100 μm, more preferably less than 90 μm, and more preferably less than 80 μm.

[0119] It is preferable that the arithmetic mean roughness Ra as the linear roughness satisfies the above-mentioned preferred numerical range in both the above-mentioned longitudinal direction and the above-mentioned transverse direction. In this case, the fixing strength can be improved with respect to the shearing force in the longitudinal direction and the transverse direction.

[0120] From the perspective of the ball biting feeling, the maximum height Rz of the outer surface of the metal rod face in the portion covered by the polyurethane layer is preferably greater than 25 μm, more preferably greater than 40 μm, and more preferably greater than 60 μm. From the perspective of the fixing strength, the maximum height Rz is also preferably larger. When the maximum height Rz is too large, the concavity and convexity of the metal rod face will be reflected to the hitting surface too much through the polyurethane layer. In this case, the contact relationship between the concavity and the spherical dimple of the ball will affect the movement of the ball. From this perspective, the above-mentioned maximum height Rz is preferably less than 400 μm, more preferably less than 390 μm, and more preferably less than 380 μm.

[0121] It is preferable that the maximum height Rz as the line roughness satisfies the above-mentioned preferred numerical range in both the above-mentioned longitudinal direction and the above-mentioned transverse direction. In this case, the fixing strength can be improved with respect to the shearing force in the longitudinal direction and the transverse direction.

[0122] From the viewpoint of the ball biting feeling, the developed area ratio Sdr of the outer surface of the metal shaft face portion in the portion covered by the polyurethane layer portion is preferably 0.12 or more, more preferably 0.2 or more, and more preferably 0.25 or more. From the viewpoint of the fixing strength, the developed area ratio Sdr is also preferably larger. Considering the preferred upper limits of the arithmetic mean roughness Ra and the maximum height Rz, the developed area ratio Sdr is preferably 10 or less, more preferably 9 or less, and more preferably 8 or less.

[0123] From the viewpoint of the ball biting feeling, the outer surface of the metal shaft face portion may also satisfy the following condition (d) in the portion covered by the polyurethane layer portion. From the viewpoint of the fixing strength, this condition (d) may also be satisfied. (d) Sdr ≥ 0.02331Ra + 0.07 In this formula, Sdr is the above-mentioned developed area ratio, and Ra is the above-mentioned arithmetic mean roughness.

[0124] From the viewpoint of the ball biting feeling, the outer surface of the metal shaft face portion may also satisfy the following condition (e) in the portion covered by the polyurethane layer portion. From the viewpoint of the fixing strength, this condition (e) may also be satisfied. (e) The arithmetic mean roughness Ra is greater than 4.5, and the developed area ratio Sdr is greater than 0.07.

[0125] From the viewpoint of the ball biting feeling, the outer surface of the metal shaft face portion may also satisfy the following (f) in the portion covered by the polyurethane layer portion. From the viewpoint of the fixing strength, this (f) may also be satisfied. (f)Sdr≥0.0049Rz+0.05 In this formula, Sdr is the above-mentioned developed area ratio, and Rz is the maximum height roughness.

[0126] From the viewpoint of suppressing the sliding of the polyurethane layer and improving the bite feeling of the ball, the depth of the metal groove is preferably 0.1 mm or more, more preferably 0.15 mm or more, and more preferably 0.2 mm or more. From the viewpoint of the fixing strength, the depth of the metal groove is also preferably larger. From the viewpoint of the strength of the metal rod face, the depth of the metal groove is preferably 2 mm or less, more preferably 1.9 mm or less, and more preferably 1.8 mm or less. The depth of the metal groove is measured in a direction perpendicular to the striking surface.

[0127] From the viewpoint of suppressing the sliding of the polyurethane layer and improving the bite feeling of the ball, the width of the metal groove is preferably 0.5 mm or more, more preferably 0.75 mm or more, and more preferably 1 mm or more. From the viewpoint of fixing strength, the width of the metal groove is also preferably larger. From the viewpoint of the strength of the metal rod face, the width of the metal groove is preferably 6 mm or less, more preferably 5.5 mm or less, and more preferably 5 mm or less. The width of the metal groove is measured by the 30-degree measurement method (internal test regulations of R&A and USGA) as a method for measuring the width of the groove in the hitting area of ​​the hitting surface. In addition, the metal groove is not a groove of the hitting surface and is therefore not restricted by the rules of golf. Therefore, the metal groove may, for example, extend along a curve, the width of the bottom of the groove may be greater than the opening width of the groove, and the cross-sectional shape may be non-objective. The intervals between multiple metal grooves may also be inconsistent. The cross-sections of the metal grooves may also be inconsistent. The cross-sectional area of ​​the metal groove can be freely set.

[0128] The adhesive preferably has excellent bonding strength between the polyurethane layer and the metal rod surface. As such an adhesive, for example, the trade names "CHEMLOK 218E", "CHEMLOK 210" and "CHEMLOK IMB1040" ("CHEMLOK" is a registered trademark) produced by LORD Japan Co., Ltd. can be used. In addition, as other adhesives, for example, the trade names "METALOC C-12" and "METALOC UA" ("METALOC" is a registered trademark) produced by Toyo Chemical Research Institute Co., Ltd. can be listed. In addition, as other adhesives, for example, a two-component mixed epoxy adhesive can be listed. As such a two-component mixed epoxy adhesive, for example, the trade names "DP420" and "DP460" sold by 3M Japan Co., Ltd. can be cited.

[0129] The method for forming the polyurethane layer is not limited. For example, the polyurethane layer can also be installed on the rear head body after being formed separately from the head body. For example, the polyurethane layer can also be formed on the head body in a mold. The polyurethane layer can also be a coating. The polyurethane layer can be formed on the head body by the following method, for example. (1) A molded body of the polyurethane layer portion molded separately from the head body is prepared, and the molded body is adhered to the head surface with an adhesive. (2) A temporary molded body of a polyurethane layer portion temporarily formed separately from a club head body is prepared, a primer is applied to a portion of a metal club face portion where the polyurethane layer portion is arranged, a component in which the temporary molded body is arranged on the primer of the metal club face portion is set in a mold, and the temporary molded body is heated and melted in the mold to mold the polyurethane layer portion. (3) An unreacted polyurethane raw material is placed in a mold provided with a metal shaft face portion and reacted to form a polyurethane layer portion on the metal shaft face portion. (4) Thermoplastic polyurethane is injection-molded (insert-molded) in a mold provided with the metal face portion, thereby molding the polyurethane layer portion on the metal face portion.

[0130] There is no limitation on the method for roughening the outer surface of the metal rod face. The outer surface of the metal rod face may be roughened by forming based on a mold or by surface processing. Examples of surface processing methods include blasting such as shot peening or sand blasting, metal etching, CNC processing, laser processing, and combinations thereof. CNC is an abbreviation for Computerized Numerical Control.

[0131] exist Figure 7 , Fig.16 , Fig.25 and Fig. 27In (a), the thickness of the polyurethane layer is indicated by the double arrow t. From the viewpoint of the bite feeling of the ball, the thickness t of the polyurethane layer in the area of ​​the hitting surface is preferably greater than 0.3 mm, more preferably greater than 0.32 mm, and more preferably greater than 0.35 mm. When the thickness t is too large, the unevenness of the metal rod surface will not easily reach the ball, and the bite feeling of the ball will be reduced. From this viewpoint, the thickness t of the polyurethane layer in the area of ​​the hitting surface is preferably less than 0.8 mm, more preferably less than 0.7 mm, and more preferably less than 0.6 mm. From the viewpoint of rebound performance, the thickness t is also preferably smaller. In addition, the thickness t of the polyurethane layer in the area of ​​the hitting surface is measured at a position where the polyurethane groove g7 is not present (refer to Fig. 27 (a)). In addition, the thickness t of the polyurethane layer portion in the striking surface region is measured at a position where the inner surface protrusion 750 is not present.

[0132] The polyurethane layer is formed by polyurethane. Polyurethane is a polymer having a urethane bond. As the polyurethane, thermoplastic polyurethane and thermosetting polyurethane can be listed. Thermoplastic polyurethane is a polyurethane that shows plasticity by heating. Generally, thermoplastic polyurethane is a polyurethane with a linear structure that is high in molecular weight to a certain extent. Thermosetting polyurethane is a polyurethane obtained by reacting a low molecular weight polyurethane prepolymer with a hardener (chain extender) to obtain a high molecular weight when the polyurethane layer is formed. Thermosetting polyurethane is also called a two-liquid hardening polyurethane. Thermosetting polyurethane includes a polyurethane with a linear structure and a polyurethane with a three-dimensional cross-linked structure, which can be generated by controlling the number of functional groups of the prepolymer or curing agent (chain extender) used. The polyurethane can be a thermoplastic elastomer.

[0133] Thermoplastic polyurethane is not particularly limited as long as it has a plurality of urethane bonds in the molecule and exhibits thermoplasticity. For example, thermoplastic polyurethane is a product obtained by reacting polyisocyanate with polyol to form urethane bonds in the molecule, and further reacting polyamine or the like as needed.

[0134] The polyisocyanate component constituting the thermoplastic polyurethane is not particularly limited as long as it has two or more isocyanate groups, and examples thereof include aromatic polyisocyanates 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-naphthalene diisocyanate (NDI), 3,3'-dimethylbiphenyl-4,4'-diisocyanate (TODI), xylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), and p-phenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate (HDI); 12MDI), hydrogenated xylene diisocyanate (H 6 XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI) and other alicyclic polyisocyanates or aliphatic polyisocyanates, or a mixture of two or more thereof.

[0135] From the viewpoint of improving scratch resistance, aromatic polyisocyanates are preferably used as the polyisocyanate component of the polyurethane. By using aromatic polyisocyanates, the mechanical properties of the obtained polyurethane are improved, and a polyurethane layer with excellent scratch resistance can be obtained. In addition, from the viewpoint of improving weather resistance, non-yellowing polyisocyanates (TMXDI, XDI, HDI, H 6 XDI、IPDI、H 12 MDI, NBDI, etc.), and more preferably 4,4'-dicyclohexylmethane diisocyanate (H 12 MDI). 4,4'-dicyclohexylmethane diisocyanate (H 12 MDI) has a rigid structure, the mechanical properties of the obtained polyurethane are improved, and a polyurethane layer with excellent scratch resistance can be obtained. From the viewpoint of improving the ball bite feeling, other polyisocyanate components can also be selected.

[0136] The polyol component constituting the thermoplastic polyurethane is not particularly limited as long as it has a plurality of hydroxyl groups, and examples thereof include low molecular weight polyols and high molecular weight polyols, etc. Examples of the low molecular weight polyol include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; and triols such as glycerol, trimethylolpropane, and hexanetriol. As the high molecular weight polyol, there can be mentioned polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), polyoxytetramethylene glycol (PTMG); condensation polyester polyols such as polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols, etc., which can be a mixture of at least two or more of the above polyols.

[0137] The average molecular weight of the high molecular weight polyol is not particularly limited, for example, preferably 400 or more, more preferably 1000 or more. This is because when the average molecular weight of the high molecular weight polyol is too small, the obtained polyurethane sometimes becomes hard, and the hitting feeling is reduced. The upper limit of the average molecular weight of the high molecular weight polyol is not particularly limited, and is 10000 or less, more preferably 8000 or less.

[0138] In addition, the polyamines constituting the above-mentioned thermoplastic polyurethane as required are not particularly limited as long as they have at least two or more amino groups. As the above-mentioned polyamines, aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, alicyclic polyamines such as isophoronediamine and piperazine, and aromatic polyamines can be cited.

[0139] The aromatic polyamine is not particularly limited as long as at least two or more amino groups are directly or indirectly bonded to an aromatic ring. Here, indirect bonding means that the amino group is bonded to the aromatic ring, for example, via a lower alkylene group. The aromatic polyamine may be, for example, a monocyclic aromatic polyamine having two or more amino groups bonded to one aromatic ring, or a polycyclic aromatic polyamine containing two or more aminophenyl groups bonded to one aromatic ring via at least one amino group.

[0140] The monocyclic aromatic polyamines include, for example, those in which the amino group is directly bonded to the aromatic ring, such as phenylenediamine, toluenediamine, diethyltoluenediamine, dimethylthiotoluenediamine, and those in which the amino group is bonded to the aromatic ring via a lower alkylene group, such as phenylenediamine. In addition, the polycyclic aromatic polyamines include poly(aminobenzene) in which at least two aminophenyl groups are directly bonded, and those in which at least two aminophenyl groups are bonded via a lower alkylene group or an oxyalkylene group. Among them, diaminodiphenylalkanes in which two aminophenyl groups are bonded via a lower alkylene group are preferred, and 4,4'-diaminodiphenylmethane and its derivatives are particularly preferred.

[0141] The constitution of the thermoplastic polyurethane is not particularly limited. Examples of the constitution include a constitution of a polyisocyanate component and a high molecular weight polyol component; a constitution of a polyisocyanate component, a high molecular weight polyol component and a low molecular weight polyol component; a constitution of a polyisocyanate component, a high molecular weight polyol component, a low molecular weight polyol component and a polyamine component; a constitution of a polyisocyanate component, a high molecular weight polyol component and a polyamine component, and the like.

[0142] Examples of the thermoplastic polyurethane include MDI-based polyurethanes using MDI as the polyisocyanate and H-based polyurethanes using H-based polyisocyanate. 12 Hydrogenated MDI is a polyurethane.

[0143] Specific examples of the thermoplastic polyurethane include "Elastollan XNY90A", "Elastollan XNY97A", ​​"Elastollan XNY585", "Elastollan 1180A10", "Elastollan 1185A50", "Elastollan 1190A10TR", "Elastollan 1195A50STR", "Elastollan 1164D50" and the like sold by BASF Japan.

[0144] In the present invention, the material of the polyurethane layer portion is not particularly limited as long as it contains polyurethane as a base resin component. When the polyurethane is a thermoplastic polyurethane, the content of the thermoplastic polyurethane in the resin component constituting the polyurethane layer component material is 50% by mass or more, more preferably 70% by mass or more, and more preferably 90% by mass or more. In addition, it is also a preferred embodiment that the resin component constituting the polyurethane layer component material is substantially composed of only polyurethane (e.g., only thermoplastic polyurethane).

[0145] In addition to the above-mentioned resin components, the polyurethane layer component material of the present invention may also contain pigment components such as white pigments (such as titanium oxide), blue pigments, red pigments, specific gravity regulators such as calcium carbonate or barium sulfate, dispersants, antioxidants, ultraviolet absorbers, light stabilizers, fluorescent materials or fluorescent whitening agents, etc. within a range that does not excessively damage the performance of the polyurethane layer.

[0146] The Shore D hardness of the striking surface is not limited. From the perspective of the striking feeling, the Shore D hardness can be set to a predetermined range. The Shore D hardness of the striking surface can be 65 or more as a lower limit, further can be 70 or more, and further can be 75 or more. The Shore D hardness of the striking surface can be 99 or less, further can be 95 or less, and further can be 90 or less as an upper limit.

[0147] The Shore D hardness of the hitting surface is measured in the state of the completed club head. The club head is stored at 23°C for two weeks, and the hardness of the hitting surface of the club head is measured using an Asker rubber hardness meter type D. The hardness is measured by pressing the hardness meter on the hitting surface of the club head. The number of n measured is set to 10, and the average value of 10 data is taken as the measured value. The measurement is performed in a location without a metal groove or a polyurethane groove.

[0148] As the preferred material of the club head body, metal and fiber reinforced plastic are exemplified. As the metal, titanium alloy, pure titanium, stainless steel, aluminum alloy, Malay steel and soft iron are exemplified. As the fiber reinforced plastic, carbon fiber reinforced plastic is exemplified. The club head body may also have a metal part and a fiber reinforced plastic part. As the material of the metal club face, titanium alloy, pure titanium, stainless steel, aluminum alloy, Malay steel and soft iron are exemplified.

[0149] Preferred materials for the metal face portion include titanium alloy, pure titanium, stainless steel, aluminum alloy, Malayan steel, and soft iron. [Example]

[0150] [Example 1] A club head identical to the club head 300 of the third embodiment is produced. The face component 300b is produced by forging. The back component 300c is produced by lost wax precision casting. The face component 300b and the back component 300c are joined by welding to obtain the club head body 300a. The material of the face component 300b is Super-TIX 51AF, and the material of the back component 300c is Ti-811Plus. The outer surface of the metal face portion M3 in the face component 300b is subjected to laser-based surface processing to increase the surface roughness. The polyurethane layer U3 is formed separately from the club head body 300a. The polyurethane layer U3 uses thermoplastic polyurethane and is produced by injection molding. As the thermoplastic polyurethane of the material of the polyurethane layer U3, MDI-based polyurethane (trade name "Elastollan 1185A50" produced by BASF) is used. The polyurethane layer U3 is pasted to the face component 300b. As an adhesive, a product name "Chemlock 210" produced by LORD Japan Co., Ltd. was used. In addition, the edge 330 of the polyurethane layer portion U3 was embedded in the groove 328 and bonded to the groove 328. In this way, the golf club head of Example 1 was obtained. The shaft and the grip were combined with the club head to obtain the golf club (length 45.5 inches) involved in Example 1.

[0151] [Examples 2 to 10] Golf club heads and golf clubs of Examples 2 to 10 were obtained by making the same specifications as in Example 1 except for the specifications shown in Tables 1 and 2 below. However, in Example 5, Fig.26 In Example 5, the width of the metal groove is 0.15 mm, and the depth of the metal groove is 0.15 mm. In addition, in Example 6, Fig. 27 That is, Example 6 has a metal groove, an inner surface protrusion, and a polyurethane groove. The width of the metal groove and the inner surface protrusion is 0.15 mm, and the depth of the metal groove and the height of the inner surface protrusion are 0.15 mm.

[0152] [Comparative Examples 1 to 4] Golf club heads and golf clubs of Comparative Examples 1 to 4 were obtained by making the same as Example 1 except for the specifications shown in Tables 1 and 2 below. In Comparative Example 4, in which the thickness t is 0 mm, no polyurethane layer is provided, and the outer surface of the metal shaft face portion is the striking surface. The roughness of the striking surface of Comparative Example 4 is a general roughness used for a metal striking surface.

[0153] The evaluation method is as follows.

[0154] [Arithmetic mean roughness Ra, maximum height Rz and developed area ratio Sdr] In the above method, the arithmetic mean roughness Ra, the maximum height Rz and the developed area ratio Sdr of the outer surface of the metal rod face portion were measured. These measured values ​​are shown in Tables 1 and 2 below.

[0155] [Thickness t of polyurethane layer] The thickness t of the polyurethane layer portion in the region of the striking surface was measured. The measured values ​​are shown in Tables 1 and 2 below.

[0156] [Bite feeling] Ten golfers with a club difference of less than 10 and a club head speed of 45 to 50 m / s when serving hit the ball with each club and evaluated the bite feeling in five stages from 1 point to 5 points. The larger the point, the higher the evaluation. As a golf ball, the trade name "Slisheng Z-STAR XV" produced by Sumitomo Rubber Industries was used. The average value of the ten golfers is shown in the "Bite Feeling" column of Tables 1 and 2 below.

[0157] [Flight distance] The ten golfers hit five balls with each club and measured the flight distance. The total flight distance including the roll was measured. As the ball, the trade name "Slisheng Z-STAR XV" produced by Sumitomo Rubber Industries was used. The average value of the flight distance of all hits is shown in the following Tables 1 and 2.

[0158] [COR] For the club face center Fc, COR was measured. COR stands for Coefficient of Restitution. COR is measured based on "Interim Procedure for Measuring the Coefficient of Restitution of an Iron Clubhead Relative to a Baseline Plate Revision 1.3 January 1, 2006" prescribed by USGA (United States Golf Association). The measured values ​​are shown in Tables 1 and 2 below.

[0159]

Table 1

[0160]

Table 2

[0161] After the above evaluation, the state of the polyurethane layer was checked for all the examples and comparative examples. In comparative examples 1 to 3, a part of the polyurethane layer peeled off from the metal shaft face. On the other hand, in examples 1 to 10, such peeling did not occur, and the close contact between the polyurethane layer and the metal shaft face was maintained.

[0162] As shown in Tables 1 and 2, the evaluations of Examples were higher than those of Comparative Examples.

[0163] The following supplementary notes are a part of the invention included in the present invention. [Note 1] A golf club head includes a club face portion forming a striking surface. The face portion includes a metal face portion formed of metal and a polyurethane layer portion, the metal face portion being formed of metal, and the polyurethane layer portion being provided on the outer side of the metal face portion and being formed of polyurethane. In the portion covered by the polyurethane layer, the line roughness of the outer surface of the metal rod face portion is such that the arithmetic mean roughness Ra is greater than 4.5 μm or the maximum height Rz is greater than 25 μm. [Note 2] In the golf club head described in Supplementary Note 1, a developed area ratio Sdr of an outer surface of the metal face portion in a portion covered by the polyurethane layer portion is 0.12 or more. [Note 3] In the golf club head described in Supplementary Note 1 or 2, in the region of the striking surface, the thickness of the polyurethane layer portion is 0.3 mm or more and 0.8 mm or less. [Note 4] In the golf club head according to any one of Supplementary Notes 1 to 3, the outer surface of the metal face portion further has at least one groove referred to as a metal groove in the portion covered by the polyurethane layer portion. [Note 5] In the golf club head described in Supplementary Note 3, The outer surface of the polyurethane layer portion further has at least one groove called a polyurethane groove. The polyurethane groove is disposed at a position that does not overlap with the metal groove. [Note 6] In the golf club head described in Supplementary Note 4 or 5, the inner surface of the polyurethane layer portion further has an inner surface protrusion that enters the metal groove. [Note 7] In the golf club head according to any one of Supplementary Notes 4 to 6, A plurality of the above-mentioned metal grooves are provided, The plurality of metal grooves include the metal grooves having groove depths different from each other. [Note 8] In the golf club head according to any one of Supplementary Notes 1 to 7, The golf club head comprises a club head body and the polyurethane layer portion, wherein the club head body includes the metal club face portion. When the plane tangent to the striking surface at the center of the club face is taken as the reference plane, the points of contact between the straight line at 45 degrees to the reference plane and the outer surface of the club head in the longitudinal section are determined, and the set of the points of contact is defined as the 45-degree boundary line, The polyurethane layer extends to the back side of the 45-degree boundary line. The head body includes an edge fixing portion that fixes an edge of the polyurethane layer portion on a back side of the 45-degree boundary line. [Note 9] The edge fixing portion is a groove, and the edge portion of the polyurethane layer portion enters the groove.

Claims

1. A golf club head comprising a club face portion forming a striking surface, characterized in that: The face portion includes a metal face portion formed of metal and a polyurethane layer portion, the metal face portion being formed of metal, and the polyurethane layer portion being provided on the outer side of the metal face portion and being formed of polyurethane. In the portion covered by the polyurethane layer, the line roughness of the outer surface of the metal rod face portion is such that the arithmetic mean roughness Ra is greater than 4.5 μm or the maximum height Rz is greater than 25 μm.

2. The golf club head according to claim 1, wherein: In the portion covered by the polyurethane layer portion, a developed area ratio Sdr of the outer surface of the metal rod face portion is 0.12 or more.

3. The golf club head according to claim 1 or 2, characterized in that: In the region of the striking surface, the polyurethane layer portion has a thickness of 0.3 mm or more and 0.8 mm or less.

4. The golf club head according to claim 1 or 2, characterized in that: The outer surface of the metal face portion further has at least one groove called a metal groove in the portion covered by the polyurethane layer portion.

5. The golf club head according to claim 4, wherein: The outer surface of the polyurethane layer portion further has at least one groove called a polyurethane groove, The polyurethane groove is arranged at a position not overlapping with the metal groove.

6. The golf club head according to claim 4, wherein: The inner surface of the polyurethane layer portion further has an inner surface protrusion that enters the metal groove.

7. The golf club head according to claim 4, wherein: A plurality of the metal grooves are provided, The plurality of metal grooves include metal grooves having groove depths different from each other.

8. The golf club head according to claim 1 or 2, characterized in that: The golf club head comprises a club head body and the polyurethane layer portion, wherein the club head body includes the metal club face portion. When the plane tangent to the striking surface at the center of the club face is taken as the reference plane, the tangent points of the straight line at 45 degrees relative to the reference plane and the outer surface of the club head in the longitudinal section are determined, and the set of the tangent points is defined as the 45-degree boundary line, The polyurethane layer extends to the back side of the 45-degree boundary line. The head body includes an edge fixing portion that fixes an edge of the polyurethane layer portion on the back side of the 45-degree boundary line.

9. The golf club head according to claim 8, wherein: The edge fixing portion is a groove into which the edge portion of the polyurethane layer portion enters.

Images