Golf ball

Abstract

A golf ball 2 includes a spherical core 4, an inner mid layer 6, an outer mid layer 8, a reinforcing layer 10, and a cover 12. When distances (%) from a central point of the core 4 to nine points and JIS-C hardnesses at the nine points, which nine points are obtained by dividing a region from the central point of the core 4 to a surface of the core 4 at intervals of 12.5% of a radius of the core 4, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. Hm1 is greater than Hm2. Hc is less than Hm1. T2 is equal to or greater than 0.5 mm but equal to or less than 1.6 mm.

Description

[0001]This application claims priority on Patent Application No. 2012-99641 filed in JAPAN on Apr. 25, 2012, Patent Application No. 2012-116542 filed in JAPAN on May 22, 2012, Patent Application No. 2012-118422 filed in JAPAN on May 24, 2012, Patent Application No. 2012-118544 filed in JAPAN on May 24, 2012, Patent Application No. 2012-124924 filed in JAPAN on May 31, 2012, and Patent Application No. 2012-124249 filed in JAPAN on May 31, 2012. The entire contents of these Japanese Patent Applications are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to golf balls. Specifically, the present invention relates to golf balls that include a solid core, a mid layer, and a cover.[0004]2. Description of the Related Art[0005]Golf players' foremost requirement for golf balls is flight performance. In particular, golf players place importance on flight performance upon a shot with a driver. Flight performance corr...

AI Technical Summary

Benefits of technology

[0018]A golf ball according to the present invention includes a spherical core, an inner mid layer positioned outside the core, an outer mid layer positioned outside the inner mid layer, and a cover positioned outside the outer mid layer. When distances (%) from a central point of the core to nine points and JIS-C hardnesses at the nine points, which nine points are obtained by dividing a region from the central point of the core to a surface of the core at intervals of 12.5% of a radius of the core, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. A Shore D hardness Hm1 of the inner mid layer is greater than a Shore D hardness Hm2 of the outer mid layer. A Shore D hardness Hc of the cover is less than the hardness Hm1. A thickness T2 of the outer mid layer is equal to or greater than 0.5 mm but equal to or less than 1.6 mm. In the golf ball according to the present invention, a hardness distribution is appropriate. In the golf ball, the energy loss is low when being hit. The golf ball has excellent resilience performance. When the golf ball is hit with a driver, the spin rate is low. The great resilience performance and the low spin rate achieve a large flight distance. When the golf ball is hit with a short iron, the spin rate is high. The golf ball has excellent controllability. In the golf ball, the local load applied when being hit is low. The golf ball has excellent durability. Furthermore, in the golf ball, soft feel at impact is obtained.

[0019]According to another aspect, a golf ball according to the present invention includes a spherical core, an inner mid layer positioned outside the core, an outer mid layer positioned outside the inner mid layer, and a cover positioned outside the outer mid layer. When distances (%) from a central point of the core to nine points and JIS-C hardnesses at the nine points, which nine points are obtained by dividing a region from the central point of the core to a surface of the core at intervals of 12.5% of a radius of the core, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. A Shore D hardness Hm2 of the outer mid layer is greater than a Shore D hardness Hm1 of the inner mid layer. A Shore D hardness Hc of the cover is less than the hardness Hm2. The hardness Hm1 is less than 50. In the golf ball according to the present invention, a hardness distribution is appropriate. In the golf ball, the energy loss is low when being hit. The golf ball has excellent resilience performance. When the golf ball is hit with a driver, the spin rate is low. The great resilience performance and the low spin rate achieve a large flight distance. When the golf ball is hit with a short iron, the spin rate is high. The golf ball has excellent controllability. In the golf ball, the local load applied when being hit is low. The golf ball has excellent durability.

[0020]According to still another aspect, a golf ball according to the present invention includes a core, a mid layer positioned outside the core, an inner cover positioned outside the mid layer, and an outer cover positioned outside the inner cover. When distances (%) from a central point of the core to nine points and JIS-C hardnesses at the nine points, which nine points are obtained by dividing a region from the central point of the core to a surface of the core at intervals of 12.5% of a radius of the core, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. A Shore D hardness Hm of the mid layer is greater than a Shore D hardness Hc1 of the inner cover. The hardness Hm is greater than a Shore D hardness Hc2 of the outer cover. A thickness T1 of the inner cover is equal to or greater than 0.1 mm but equal to or less than 0.8 mm. In the golf ball according to the present invention, a hardness distribution is appropriate. In the golf ball, the energy loss is low when being hit. When the golf ball is hit with a driver, the spin rate is low. The low spin rate achieves a large flight distance. When the golf ball is hit with a short iron, the spin rate is high. The golf ball has excellent controllability.

[0021]According to still another aspect, a golf ball according to the present invention includes a core, a mid layer positioned outside the core, an inner cover positioned outside the mid layer, and an outer cover positioned outside the inner cover. When distances (%) from a central point of the core to nine points and JIS-C hardnesses at the nine points, which nine points are obtained by dividing a region from the central point of the core to a surface of the core at intervals of 12.5% of a radius of the core, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. A Shore D hardness Hm of the mid layer is greater than a Shore D hardness Hc1 of the inner cover. A Shore D hardness Hc2 of the outer cover is greater than the hardness Hc1. In the golf ball according to the present invention, a hardness distribution is appropriate. In the golf ball, the energy loss is low when being hit. When the golf ball is hit with a driver, the spin rate is low. The low spin rate achieves a large flight distance. When the golf ball is hit with a short iron, the spin rate is high. The golf ball has excellent controllability.

Problems solved by technology

With a golf ball that achieves a high trajectory by a high spin rate, a flight distance is insufficient.

When a backspin rate is high, the run is short.

When being hit with a driver or the like, a golf ball receives great shock and deforms.

When a local load is applied to a part of the ball due to the deformation, the golf ball is broken.

However, a golf ball having a low spin rate has inferior controllability.

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