JP2020081607A - Golf ball - Google Patents

Abstract

To provide a golf ball for amateur golfers with an excellent flight when hit by an average golfer whose head speed is not so high and also has a good feel at impact that is soft and solid on full shots with all golf club numbers.SOLUTION: A golf ball includes a core and a cover, and, in a compression deformation of the golf ball, has a compressive deformation (A) of 0.21 mm or less when the ball is subjected to a final load of 5 kg from an initial load state of 0.2 kg and a compressive deformation (B) of 0.73 to 0.95 mm when the ball is subjected to a final load of 30 kg from an initial load state of 5 kg. Also, letting (D) be a compressive deformation of the ball when the ball is subjected to a final load 130 kg from an initial load state of 10 kg and (C) be a compressive deformation of the ball when the ball is subjected to a final load of 60 kg from an initial load state of 5 kg, the golf ball satisfies a value (D)/(A) of 16.0 to 20.5 and a value (D)/(C) of 1.80 to 1.90.SELECTED DRAWING: Figure 1

Description

The present invention relates to a golf ball having a core and a cover, which is for an amateur user who does not have a high head speed.

In the market of golf balls for amateur golfers, many golf balls have hitherto been developed that satisfy an amateur golfer in flight and feel. For example, as an index of the influence on the ball characteristics when a small impact force is applied to a golf ball, the amount of compressive deformation from the state where an initial load of 0.2 kg is applied to the final load of 5 kg is used. A golf ball having a range of 0.26 to 0.40 mm is proposed in Japanese Patent Laid-Open No. 8-280845 (Patent Document 1). However, this golf ball is a spin type golf ball that places importance on approach spin, and is not sufficiently satisfactory in flight performance when hit by a driver.

In addition, various functional multi-piece solid golf balls have been proposed in which the ball structure is multilayered and the surface hardness of each of the core, surrounding layer, intermediate layer and cover (outermost layer) is optimized. For example, JP-A-2014-132955 (Patent Document 2), JP-A-2015-173860 (Patent Document 3), JP-A-2016-16117 (Patent Document 4), and JP-A-2016-179052 (Patent) The multi-piece solid golf ball described in Reference 5) is mentioned. The golf balls described in these publications satisfy a hardness relationship of ball surface hardness> middle layer surface hardness> surrounding layer surface hardness <core surface hardness, and are excellent even for an amateur golfer who does not have a high head speed. It gives performance. However, the golf ball proposed above has a compressive deformation amount from a state in which an initial load of 0.2 kg is applied to a final load of 5 kg, and a compression deformation amount from an initial load of 5 kg to a final load of 30 kg. It is not a thing that the amount of compressive deformation is optimized, that is, it does not focus on how the ball characteristics affect the impact force applied to the golf ball, and as a golf ball product for amateur users, There is still room for improvement in terms of performance and good feel.

JP-A-8-280845 JP, 2014-132955, A JP, 2005-173860, A JP, 2016-16117, A JP, 2016-179052, A

The present invention has been made in view of the above circumstances, the head speed is not so fast, the so-called average golfer is excellent in flying when hit, and in all the counts to make a full shot, a good hit with a soft and flying feeling. It is an object of the present invention to provide a golf ball for an amateur user who has a feeling of feeling.

As a result of intensive studies to achieve the above object, the present inventors have found that, in a golf ball including a core and a cover, the relationship between the degree of impact force applied to the golf ball and the ball characteristics of flight/hit feel. Focusing on the amount of compressive deformation of the golf ball, specifically, the amount of compressive deformation (A) from when the initial load of 0.2 kg was applied to when the final load of 5 kg was applied, and when the initial load of 5 kg was applied. Compressive deformation amount (B) until a final load of 30 kg is applied, compressive deformation amount (D) from a state where an initial load of 10 kg is applied to a final load of 130 kg, and more preferably, an initial load of 5 kg is applied. By specifying each compression deformation amount of the compression deformation amount (C) from the state where the final load is applied to 60 kg and the ratio thereof, a golfer whose head speed is not fast can drive a driver (W#1) or an iron shot. It was found that a satisfactory flight performance can be obtained when hit with all clubs such as, and a hit feeling that achieves both a soft feeling and a flying feeling can be obtained in all counts for full shots. The present invention has led to the invention of the golf ball.

Therefore, the present invention provides the following golf balls.
[1] A golf ball comprising a core and a cover, wherein the amount of compressive deformation (A) from the state of applying an initial load of 0.2 kg to the final load of 5 kg is (A) in the amount of compressive deformation of the golf ball. 0.21 mm or less, the amount of compressive deformation (B) from the state of applying an initial load of 5 kg to the final load of 30 kg of 0.73 to 0.95 mm, and an initial load of 10 kg To (D) the amount of compressive deformation from the application of a final load of 130 kg to (D), and the amount of compressive deformation from the state of applying an initial load of 5 kg to the final load of 60 kg (C),
Value of (D)/(A): 16.0 to 20.5, and value of (D)/(C): 1.80 to 1.90
A golf ball that satisfies:
[2] The golf ball according to [1], wherein the amount of compressive deformation (C) is 1.55 to 1.80 mm.
[3] The golf ball according to [1] or [2], wherein the compression deformation amount (D) is 2.80 to 3.40 mm.
[4] Any of the above [1] to [3], wherein the ratio (D)/(B) of the amount of compressive deformation (D) to the amount of compressive deformation (B) is 3.65 to 4.20. The golf ball described in Crab.
[5] At least an intermediate layer is included between the core and the cover, and the golf ball structure has three or more layers including a core, an intermediate layer, and a cover. 4] The golf ball according to any one of 4).
[6] At least an envelope layer and an intermediate layer are included between the core and the cover, and the golf ball structure has four or more layers including the core, the envelope layer, the intermediate layer and the cover. The golf ball according to any one of the above [1] to [4].
[7] The following relational expression (1) of surface hardness
Shore D hardness of cover surface> Shore D hardness of intermediate layer surface> Shore D hardness of envelope layer surface> Shore D hardness of core center (1)
The golf ball according to the above [6], which satisfies the above condition.
[8] The golf ball according to any one of [1] to [7], wherein the hardness difference (Cs-Cc) between the center and the surface of the core is 20 or more in Shore C hardness.
[9] The golf ball according to any one of the above [1] to [8], wherein a coating layer is formed on the surface of the cover, and the material hardness of the coating layer is higher than the core hardness (Cc).
[10] The golf ball according to any one of the above [6] to [9], which satisfies the following initial velocity relational expressions (2), (3) and (4).
−0.8 m/s≦(ball initial velocity−core initial velocity)≦0 m/s (2)
−0.4 m/s≦(ball initial velocity−intermediate layer-coated sphere initial velocity)≦0.4 m/s
...(3)
0 m/s ≤ (initial velocity of intermediate layer-coated sphere-initial velocity of envelope layer-coated sphere) ≤ 0.4 m/s
...(4)
[11] A golf ball having a core and a cover, wherein the amount of compressive deformation of the golf ball from a state in which an initial load of 0.2 kg is applied to a final load of 5 kg is (A). , (B) the amount of compressive deformation from the state of applying an initial load of 5 kg to the final load of 30 kg (B), and the amount of compressive deformation from the state of applying an initial load of 5 kg to the final load of 60 kg (C) When the amount of compressive deformation from the state where an initial load of 10 kg is applied to when the final load of 130 kg is applied is (D), the value of (C) is 1.55 to 1.80 mm, and the value of (D) is Is 2.80 to 3.40 mm, and
Value of (D)/(A): 16.0 to 20.5, and value of (D)/(B): 3.65 to 4.20
A golf ball that satisfies:
[12] At least an envelope layer and an intermediate layer are included between the core and the cover, and the structure of the golf ball is composed of four or more layers including the core, the envelope layer, the intermediate layer and the cover. The golf ball according to the above [11].

The golf ball of the present invention has excellent flight performance when hit by a golfer whose head speed is not so fast, and has a good hit feeling with a soft and flight feeling, and is suitable as a golf ball for amateur users. is there.

1 is a schematic cross-sectional view of a golf ball (4 layer structure) according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention has a core and a cover. In the present invention, the cover is a member located in the outermost layer in the ball structure, and is usually formed by molding such as injection molding. Further, a large number of dimples are usually formed on the outer surface of the cover simultaneously with the injection molding of the cover material.

The diameter of the core is preferably 34.0 mm or more, more preferably 34.5 mm or more, further preferably 35.0 mm or more, and the upper limit is preferably 37.0 mm or less, more preferably 36.5 mm or less, It is preferably 36.0 mm or less. If the diameter of the core is too small, the spin may increase when hit by a driver (W#1), and the desired flight distance may not be obtained. On the other hand, if the diameter of the core is too large, the durability against repeated impact may deteriorate or the feel on impact may deteriorate.

The amount of compressive deformation (mm) from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) applied to the core is not particularly limited, but is preferably 3.0 mm or more, more preferably It is 3.5 mm or more, more preferably 4.0 mm or more, and the upper limit value is preferably 7.0 mm or less, more preferably 6.0 mm or less, and further preferably 5.0 mm or less. If the amount of compressive deformation of the core is too small, that is, if the core is too hard, the spin of the ball may increase so much that the ball may not fly and the feel may be too hard. On the other hand, if the amount of compressive deformation of the core is too large, that is, if the core is too soft, the resilience of the ball becomes too low to fly and the feel at impact becomes too soft, or the crack durability upon repeated hitting is poor. May be.

The core is formed of a single layer or multiple layers of rubber material. As the rubber material for the core, specifically, a base rubber is mainly used, and a rubber composition is prepared by mixing a co-crosslinking agent, an organic peroxide, an inert filler, an organic sulfur compound and the like. Can be created. It is preferable to use polybutadiene as the base rubber.

As the type of polybutadiene, commercially available products can be used, and examples thereof include BR01, BR51, BR730 (manufactured by JSR Corporation). The proportion of polybutadiene in the base rubber is preferably 60% by mass or more, more preferably 80% by mass or more. In addition to the polybutadiene, other rubber components may be blended with the base rubber within a range that does not impair the effects of the present invention. Examples of the rubber component other than the polybutadiene include polybutadiene other than the polybutadiene and other diene rubbers such as styrene butadiene rubber, natural rubber, isoprene rubber, and ethylene propylene diene rubber.

Examples of the co-crosslinking agent include unsaturated carboxylic acids and metal salts of unsaturated carboxylic acids. Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like, and acrylic acid and methacrylic acid are particularly preferably used. The metal salt of unsaturated carboxylic acid is not particularly limited, and examples thereof include those obtained by neutralizing the above unsaturated carboxylic acid with a desired metal ion. Specific examples thereof include zinc salts and magnesium salts of methacrylic acid and acrylic acid, and zinc acrylate is particularly preferably used.

The unsaturated carboxylic acid and/or metal salt thereof is usually 5 parts by mass or more, preferably 9 parts by mass or more, more preferably 13 parts by mass or more, and generally 60 parts by mass as the upper limit, relative to 100 parts by mass of the base rubber. The following is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. If the blending amount is too large, the ball may be too hard and may have an unbearable feel, and if the blending amount is too small, the resilience may decrease.

As the organic peroxide, a commercially available product can be used. For example, Percumil D (manufactured by NOF CORPORATION), Perhexa C-40, Perhexa 3M (manufactured by NOF CORPORATION), Luperco 231XL (manufactured by Atochem Co., Ltd.). ) Etc. can be used suitably. These may be used alone or in combination of two or more. The content of the organic peroxide is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, still more preferably 0.5 part by mass or more, and most preferably 100 parts by mass of the base rubber. Is 0.6 parts by mass or more, and the upper limit is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, further preferably 3 parts by mass or less, and most preferably 2.5 parts by mass or less. If the blending amount is too large or too small, suitable hit feeling, durability and rebound may not be obtained.

In addition, as a compounding agent to be compounded with the base rubber, an inert filler may be mentioned, and for example, zinc oxide, barium sulfate, calcium carbonate and the like can be preferably used. These may be used alone or in combination of two or more. The content of the inert filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and the upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, relative to 100 parts by mass of the base rubber. And more preferably 35 parts by mass or less. If the blending amount is too large or too small, it may not be possible to obtain a proper mass and a suitable resilience.

Furthermore, if necessary, an antioxidant can be added, and for example, as commercially available products, Nocrac NS-6, Nocrac NS-30 (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), Yoshinox 425 (Yoshitomi Pharmaceutical Co., Ltd. ) Made) etc. are mentioned. These may be used alone or in combination of two or more.

The amount of the antioxidant added is 0 parts by mass or more, more preferably 0.05 parts by mass or more, particularly preferably 0.1 parts by mass or more, and the upper limit is preferably 3 with respect to 100 parts by mass of the base rubber. The amount is not more than 2 parts by mass, more preferably not more than 2 parts by mass, particularly preferably not more than 1 part by mass, most preferably not more than 0.5 parts by mass. If the blending amount is too large or too small, suitable resilience and durability may not be obtained.

In addition, an organic sulfur compound can be added to the core in order to impart good resilience. The organic sulfur compound is not particularly limited as long as it can improve the resilience of the golf ball, and examples thereof include thiophenols, thionaphthols, halogenated thiophenols and metal salts thereof. More specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, parachlorothiophenol, zinc salt of pentachlorothiophenol, zinc salt of pentafluorothiophenol, zinc salt of pentabromothiophenol, Examples include zinc salt of parachlorothiophenol, diphenyl polysulfide having 2 to 4 sulfur, dibenzyl polysulfide, dibenzoyl polysulfide, dibenzothiazoyl polysulfide, dithiobenzoyl polysulfide and the like, and zinc salt of pentachlorothiophenol is particularly preferable. Used for. The compounding amount of the organic sulfur compound is 0 part by mass or more, more preferably 0.1 part by mass or more, still more preferably 0.2 part by mass or more, and as the upper limit, preferably 100 parts by mass of the base rubber. It is recommended that the amount is 5 parts by mass or less, more preferably 3 parts by mass or less, and further preferably 2 parts by mass or less. If the blending amount is too large, the effect of improving resilience (particularly, hitting with W#1) cannot be expected any more, and the core may be too soft or the feel may be poor. On the other hand, if the blending amount is too small, the effect of improving the resilience cannot be expected.

More specifically, by directly blending water (a material containing water) into the above core material, the decomposition of the organic peroxide during the blending of the core can be promoted. Further, it is known that the decomposition efficiency of the organic peroxide in the rubber composition for the core changes depending on the temperature, and the decomposition efficiency increases as the temperature becomes higher than a certain temperature. If the temperature is too high, the amount of decomposed radicals will be too large, and the radicals will be recombined or inactivated. As a result, the number of radicals effectively working for crosslinking is reduced. Here, when decomposition heat is generated due to decomposition of the organic peroxide during core vulcanization, the temperature near the core surface is maintained at about the same temperature as the vulcanization mold, but the temperature near the center of the core is outside. Since the heat of decomposition of the organic peroxide decomposed from is accumulated, the temperature becomes considerably higher than the mold temperature. When water (a material containing water) is directly added to the core, water has a function of promoting the decomposition of the organic peroxide, so that the radical reaction as described above can be changed at the core center and the core surface. it can. That is, in the vicinity of the center of the core, the decomposition of the organic peroxide is further promoted, and the inactivation of the radicals is further promoted, so that the amount of effective radicals is further reduced, so that the crosslinking density between the core center and the core surface is significantly different. It is possible to obtain a core having different dynamic viscoelastic properties at the core center.

The water to be blended with the core material is not particularly limited and may be distilled water or tap water, but it is particularly preferable to use distilled water containing no impurities. It The amount of water blended is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and the upper limit is preferably 5 parts by mass or less with respect to 100 parts by mass of the base rubber. And more preferably 4 parts by mass or less.

The core can be produced by vulcanizing and curing a rubber composition containing the above components. For example, kneading is performed using a kneading machine such as a Banbury mixer or a roll, compression molding or injection molding is performed using a core mold, and a temperature sufficient to allow the organic peroxide and the co-crosslinking agent to act is 100 to By appropriately heating the molded body under the conditions of 200° C., preferably 140 to 180° C. and 10 to 40 minutes, the molded body can be cured to be manufactured.

The core may be formed not only in a single layer but also in two layers of an inner layer core and an outer layer core. When the core is formed in two layers of the inner layer core and the outer layer core, the rubber material described above can be used as the main material as the material of the inner layer and the outer layer core. Further, the rubber material of the outer core covering the inner core may be the same as or different from the material of the inner core. Specifically, it is the same as that described for each component of the rubber material of the core.

Next, the hardness distribution of the core will be described.

The center hardness (Cc) of the core is preferably 50 or more, more preferably 53 or more, still more preferably 55 or more in Shore C hardness, and the upper limit thereof is preferably 65 or less, more preferably 62 or less, It is preferably 60 or less. If this value is too large, the feel may be hard, or the spin may increase at full shot, and the desired flight distance may not be obtained. On the other hand, when the above value is too small, the resilience may be lowered and the ball may not fly, or the crack durability upon repeated impact may be deteriorated. The Shore C hardness is a hardness value measured by a Shore C hardness meter according to the ASTM D2240 standard.

Further, the center hardness (Cc) of the core, expressed in Shore D hardness, is preferably 26 or more, more preferably 28 or more, further preferably 30 or more, and the upper limit value is preferably 40 or less, more preferably 37. Below, it becomes 34 or less more preferably.

The surface hardness (Cs) of the core is a Shore C hardness of preferably 73 or more, more preferably 77 or more, further preferably 79 or more, and the upper limit thereof is preferably 89 or less, more preferably 87 or less, It is preferably 85 or less. Deviations from these hardnesses may lead to the same adverse results as described for the core hardness (Cc).

The surface hardness (Cs) of the core, expressed in Shore D hardness, is preferably 40 or more, more preferably 43 or more, still more preferably 45 or more, and the upper limit is preferably 54 or less, more preferably 52. Below, it becomes 50 or less more preferably.

The difference between the surface hardness (Cs) of the core and the center hardness (Cc) of the core is preferably 20 or more, more preferably 22 or more, still more preferably 24 or more in Shore C hardness, and the upper limit is preferably 32. Or less, more preferably 30 or less. If this value is too small, the low spin effect of the ball when shot with a driver may be insufficient and the flight distance may not be achieved. If the above value is too large, the initial velocity of the ball at the time of actual striking may be low and the flight distance may not be long, or the crack durability upon repeated striking may be poor.

Next, the cover will be described.
Although the material hardness of the cover is not particularly limited, it is Shore D hardness, preferably 55 or more, more preferably 59 or more, further preferably 61 or more, and the upper limit value is preferably 70 or less, more preferably 68 or less. , And more preferably 65 or less. Further, the cover surface hardness (also referred to as ball surface hardness) is Shore D hardness, preferably 61 or more, more preferably 65 or more, further preferably 67 or more, and the upper limit value is preferably 76 or less. It is preferably 74 or less, more preferably 71 or less. If the material hardness and the ball surface hardness of these covers are too softer than the above ranges, spin may increase when hit with a driver (W#1), the initial velocity of the ball may decrease, and the flight distance may not be achieved. If the material hardness and the surface hardness are too hard, the crack durability during repeated impact durability may deteriorate.

The thickness of the cover is preferably 0.6 mm or more, more preferably 0.8 mm or more, still more preferably 1.1 mm or more. On the other hand, the upper limit of the thickness of the cover is preferably 1.5 mm or less, more preferably 1.4 mm or less, and further preferably 1.3 mm or less. If this cover is too thin, the durability to cracking by repeated impact may deteriorate. On the other hand, if the cover is too thick, the spin amount at the time of hitting the driver (W#1) may be too large and the flight distance may not be long, or the hit feeling of the short game and putter may be too hard.

As the material for the cover, it is preferable to employ various thermoplastic resins used in the cover material for golf balls, particularly ionomer resins, and commercially available ionomer resins can be used. Further, as a resin material for the cover, a high acid content ionomer resin having an acid content of 18% by mass or more among commercially available ionomer resins can be blended with a normal ionomer resin to be used, and by this blending, high resilience and low spin are obtained. It is possible to obtain a good flight distance at the time of hitting the driver (W#1). Such high acid content ionomer resin is preferably 10% by mass or more, more preferably 30% by mass or more, further preferably 60% by mass or more in 100% by mass of the resin material, and the upper limit value is usually 100% by mass or less. , Preferably 90 mass% or less, more preferably 80 mass% or less. If the amount of the above-mentioned ionomer resin having a high acid content is too small, the spin rate may increase when hit with a driver (W#1) and the flight distance may not be achieved. On the other hand, if the amount of the above-mentioned ionomer resin having a high acid content is too large, the durability to cracking during repeated impact durability may deteriorate.

An envelope layer and an intermediate layer described below can be provided between the core and the cover. That is, the preferred ball structure of the present invention is not limited to a two-piece golf ball having a core and a cover (single layer), and a three-piece golf ball or a four-piece golf ball can be adopted. In particular, it is preferable to use a golf ball having three layers including a core, an intermediate layer and a cover, and a golf ball having four layers including a core, an envelope layer, an intermediate layer and a cover. For example, the golf ball G shown in FIG. 1 may be mentioned. The golf ball G shown in FIG. 1 has a core 1, an envelope layer 2 that covers the core 1, an intermediate layer 3 that covers the envelope layer, and the intermediate layer. It has a cover 4 for covering 3. The cover 4 is located at the outermost layer in the layer structure of the golf ball except the coating layer. Each of the intermediate layer and the surrounding layer may be a single layer or two or more layers. A large number of dimples D are usually formed on the surface of the cover (outermost layer) 4 in order to improve aerodynamic characteristics. A coating layer 5 is formed on the surface of the cover 4.

The envelope layer will be described below.
The material hardness of the envelope layer is not particularly limited, but is preferably a Shore D hardness of 20 or more, more preferably 23 or more, further preferably 27 or more, and the upper limit value thereof is preferably 45 or less, more preferably 42. Or less, more preferably 40 or less. The surface hardness of the sphere (enveloping layer-covered sphere) in which the core is covered with the enveloping layer is Shore D hardness, which is preferably 28 or more, more preferably 31 or more, and further preferably 35 or more. It is preferably 53 or less, more preferably 50 or less, still more preferably 48 or less. When the material hardness and the surface hardness of these envelope layers are too softer than the above ranges, the spin amount of the ball at the time of a full shot may be too large and the flight distance may not be obtained, or the crack durability due to repeated hits may be deteriorated. .. If the above material hardness and surface hardness are too hard, the durability to cracking by repeated hits may deteriorate, or the spin rate at full shot may increase, resulting in poor flight distance, especially at low head speed, and poor feel at impact. is there.

The thickness of the envelope layer is preferably 0.7 mm or more, more preferably 0.9 mm or more, still more preferably 1.1 mm or more. On the other hand, the upper limit of the thickness of the envelope layer is preferably 1.5 mm or less, more preferably 1.4 mm or less, and further preferably 1.3 mm or less. If the envelope layer is too thin, the durability to cracking due to repeated impacts may deteriorate, or the feel on impact may deteriorate. On the other hand, if the envelope layer is too thick, the spin amount of the ball at the time of a full shot may increase and the flight distance may not be achieved.

The material for the envelope layer is not particularly limited, but various thermoplastic resin materials can be suitably used, and specifically, ionomer resin, urethane-based, amide-based, ester-based, olefin-based, styrene It is possible to use thermoplastic elastomers such as those of the system and mixtures thereof, and in particular, thermoplastic polyetherester elastomers are preferable from the viewpoint that good rebound can be obtained in a desired hardness range.

There is no particular limitation on the amount of compressive deformation (mm) from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) applied to the sphere having the core covered with the enveloping layer (enveloping layer-covered sphere). However, it is preferably 3.4 mm or more, more preferably 3.8 mm or more, further preferably 3.9 mm or more, and the upper limit value is preferably 4.7 mm or less, more preferably 4.5 mm or less, and further preferably It is 4.4 mm or less. If the amount of compressive deformation of the sphere is too small, that is, if the sphere is too hard, the spin of the ball may increase so much that the ball may not fly and the feel may be too hard. On the other hand, if the amount of compressive deformation of the sphere is too large, that is, if the sphere is too soft, the resilience of the ball becomes too low to fly, the feel at impact becomes too soft, or the crack durability upon repeated hits is high. It may get worse.

Next, the intermediate layer will be described below.
The material hardness of the intermediate layer is not particularly limited, but is a Shore D hardness of preferably 40 or more, more preferably 45 or more, further preferably 50 or more, and the upper limit value is preferably 62 or less, more preferably 60. Or less, more preferably 58 or less. The surface hardness of a sphere (intermediate layer-covered sphere) obtained by coating the envelope layer-covered sphere with an intermediate layer is Shore D hardness, preferably 46 or more, more preferably 51 or more, still more preferably 56 or more, and the upper limit value. Is preferably 68 or less, more preferably 66 or less, and further preferably 64 or less. If the material hardness and the surface hardness of these intermediate layers are too softer than the above ranges, the spin amount at the time of a full shot may increase too much, and the flight distance may not be obtained or the flight feeling may be lost. If the material hardness and the surface hardness are too hard, the durability to cracking due to repeated impacts may deteriorate and the soft feel may be lost.

The thickness of the intermediate layer is preferably 0.7 mm or more, more preferably 0.9 mm or more, still more preferably 1.1 mm or more. On the other hand, the upper limit of the thickness of the intermediate layer is preferably 1.5 mm or less, more preferably 1.4 mm or less, still more preferably 1.35 mm or less. If this intermediate layer is too thin, the durability to cracking due to repeated impact may deteriorate, or the feel on impact may deteriorate. On the other hand, if the intermediate layer is too thick, the spin amount of the ball at the time of full shot may increase and the flight distance may not be achieved.

As a material for forming the intermediate layer, a known resin can be used and is not particularly limited, but examples of preferable materials include the following components (A) to (D),
(A-1) Metal ion neutralized product of olefin-unsaturated carboxylic acid binary random copolymer and/or olefin-unsaturated carboxylic acid binary random copolymer,
(A-2) Metal ion neutralized product of olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer and/or olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer And (A) a base resin in which the mass ratio is 100:0 to 0:100,
(C) Fatty acid having a molecular weight of 228 to 1500 and/or a derivative thereof with respect to 100 parts by mass of the resin component in which the non-ionomer thermoplastic elastomer is mixed in a mass ratio of 100:0 to 50:50. 5 to 120 parts by mass and (D) 0.1 to 17 parts by mass of a basic inorganic metal compound capable of neutralizing the unneutralized acid groups in the components (A) and (C) are blended as essential components. An example of the resin composition is as follows.

As the components (A) to (D), for example, the resin materials (A) to (D) of the intermediate layer described in JP 2010-253268 A can be preferably used.

In addition, a non-ionomer thermoplastic elastomer can be blended with the above-mentioned intermediate layer material. The blending amount of the non-ionomer thermoplastic elastomer is preferably 0 to 50 parts by mass with respect to 100 parts by mass of the total amount of the base resin.

Examples of the non-ionomer thermoplastic elastomer include polyolefin elastomers (including polyolefins and metallocene polyolefins), polystyrene elastomers, diene polymers, polyacrylate polymers, polyamide elastomers, polyurethane elastomers, polyester elastomers, polyacetals, etc. Can be mentioned.

The intermediate layer material may be appropriately blended with any additive depending on the application. For example, various additives such as pigments, dispersants, antiaging agents, ultraviolet absorbers and light stabilizers can be added. When these additives are blended, the blending amount is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and the upper limit is preferably 100 parts by mass with respect to the total amount of the base resin. It is 10 parts by mass or less, and more preferably 4 parts by mass or less.

The amount of compressive deformation (mm) from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) for the sphere (intermediate layer-coated sphere) obtained by coating the envelope layer-coated sphere with the intermediate layer is: There is no particular limitation, but it is preferably 3.3 mm or more, more preferably 3.45 mm or more, further preferably 3.6 mm or more, and the upper limit value is preferably 4.2 mm or less, more preferably 4.1 mm or less, More preferably, it is 4.0 mm or less. If the amount of compressive deformation of the sphere is too small, that is, if the sphere is too hard, the spin of the ball may increase so much that the ball may not fly and the feel may be too hard. On the other hand, if the amount of compressive deformation of the sphere is too large, that is, if the sphere is too soft, the resilience of the ball becomes too low to fly, or the feel at impact becomes too soft, or the crack durability upon repeated hits is high. It may get worse.

The method for producing the multi-piece solid golf ball formed by laminating the core, the surrounding layer, the intermediate layer and the cover (outermost layer) described above can be carried out by a conventional method such as a known injection molding method. For example, a multi-piece golf ball can be obtained by sequentially injecting an envelope layer material and an intermediate layer material around the core to obtain an intermediate layer-covered sphere, and then injection molding the material of the cover. Alternatively, a golf ball can be produced by wrapping the coated spheres with two half cups each having a half-shell sphere shape in advance as each coating layer and subjecting the coated spheres to heat-pressing.

The amount of compressive deformation (A) from the state where an initial load of 0.2 kg is applied to the final load of 5 kg of the golf ball of the present invention is preferably 0.21 mm or less, and more preferably 0.19 mm or less. , And more preferably 0.17 mm or less. This lower limit value is preferably 0.10 mm or more, more preferably 0.12 mm or more, and further preferably 0.15 mm or more. When this value decreases, if it is due to the cover hardness, the cover may be too hard and the durability to cracking upon repeated impact may deteriorate. Further, when the above value is small due to the compression of the inner layer, the shot feeling of the ball at the time of full shot may be too hard. On the other hand, when the above value becomes large, if it is due to the cover hardness, the spin amount of the ball at the time of a full shot may increase and the flight distance may not be achieved. Further, when the above value is increased due to the compression of the inner layer, the ball may lose the feeling of rebound at full shot and the flight distance may not be achieved.

The amount of compressive deformation (B) of the golf ball of the present invention from a state where an initial load of 5 kg is applied to a final load of 30 kg is preferably 0.73 mm or more, and more preferably 0.74 mm or more. The upper limit value is preferably 0.95 mm or less, more preferably 0.90 mm or less, and further preferably 0.88 mm or less. If this value is small, the feel may be too hard when hit with a utility (UT) or an iron. On the other hand, when the above value is large, the feeling of hitting when hit with a utility (UT) or an iron becomes small, and the flight distance may not be achieved.

The amount of compressive deformation (C) of the golf ball of the present invention from an initial load of 5 kg to a final load of 60 kg is preferably 1.55 mm or more, more preferably 1.56 mm or more, and more preferably Is 1.58 mm or more. The upper limit value is preferably 1.80 mm or less, more preferably 1.78 mm or less, and further preferably 1.77 mm or less. If this value is small, the feel may be too hard when hit with a utility (UT) or an iron. On the other hand, when the above value is large, the feeling of hitting when hit with a utility (UT) or an iron becomes small, and the flight distance may not be achieved.

The amount of compressive deformation (D) of the golf ball of the present invention from an initial load of 10 kg to a final load of 130 kg is preferably 2.80 mm or more, more preferably 2.90 mm or more, and further preferably. Is 2.95 mm or more, and the upper limit is preferably 3.40 mm or less, more preferably 3.34 mm or less, and further preferably 3.28 mm or less. If this value is small, the amount of spin of the ball may increase and the ball may not fly, or the feel may be too hard. On the other hand, when the above value is large, the ball resilience may be too low to fly, the feel may be too soft, or the crack durability upon repeated impact may be poor.

The value of the ratio (D)/(C) between the amount of compressive deformation (D) and the amount of compressive deformation (C) is preferably 1.80 to 1.90. If the distance is out of this range, the feeling of flight may deteriorate and the flight distance may be reduced.

The ratio (D)/(B) of the amount of compressive deformation (D) and the amount of compressive deformation (B) is preferably 3.65 or more, more preferably 3.67 or more, and further preferably. It is 3.69 or more. On the other hand, the upper limit value is preferably 4.20 or less, more preferably 4.15 or less, and further preferably 4.10 or less. If the distance is out of this range, the feeling of flight may deteriorate and the flight distance may be reduced.

The ratio (D)/(A) of the amount of compressive deformation (D) and the amount of compressive deformation (A) is preferably 16.0 or more, more preferably 17.0 or more, and further preferably. It is 17.5 or more. On the other hand, the upper limit value is preferably 20.5 or less, more preferably 20.3 or less, and further preferably 20.0 or less. If this value is out of the above range, the ball may be over-spun, the actual initial velocity may be low, and the flight distance may be reduced depending on the club number.

[ Relationship between surface hardness of each layer ]
In the present invention, it is preferable that the following mathematical formula (1) be satisfied regarding the hardness relationship of each layer.
Shore D hardness of cover surface> Shore D hardness of intermediate layer surface> Shore D hardness of envelope layer surface> Shore D hardness of core center (1)
The hardness of the cover surface means the surface hardness of the ball. The hardness of the intermediate layer surface means the surface hardness of the intermediate layer-covering sphere, and the hardness of the envelope layer surface means the surface hardness of the envelope-layer-covering sphere.
If the hardness relationship described above is not satisfied, it may be impossible to obtain a good flying feel and a hit feeling having both a soft hit feeling and a hit feeling.

According to the above formula, the cover surface hardness is higher than the intermediate surface hardness. The value of cover surface hardness-intermediate layer surface hardness is Shore D hardness, preferably 1 to 14, more preferably 3 to 10, and further preferably 5 to 8. If this value is small, the spin amount of the ball at the full shot may increase and the flight distance may not be achieved. On the other hand, if this value is large, the feel on impact may deteriorate, and the durability to cracking due to repeated impact may deteriorate.

According to the above formula, the surface hardness of the intermediate layer is larger than the surface hardness of the envelope layer. The value of the intermediate layer surface hardness-enveloping layer surface hardness is Shore D hardness, preferably 10 to 28, more preferably 13 to 26, and further preferably 15 to 24. If this value is small, the spin amount of the ball at the full shot may increase and the flight distance may not be achieved. On the other hand, if this value is large, the feel on impact may deteriorate, and the durability to cracking due to repeated impact may deteriorate.

According to the above formula, the surface hardness of the envelope layer is higher than the core hardness. The value of envelope layer surface hardness-core center hardness is Shore D hardness, preferably 3 to 23, more preferably 5 to 20, and further preferably 7 to 17. Further, the value of envelope layer surface hardness-core surface hardness is Shore D hardness, preferably -20 to 8, more preferably -15 to 5, and still more preferably -10 to 2. If these values are small, the spin amount of the ball at the full shot may increase and the flight distance may not be achieved. On the other hand, when these values are large, the feel on impact may be poor, or the durability to cracking by repeated impacts may be poor.

The value of core surface hardness-ball surface hardness is Shore D hardness, preferably -30 to -10, more preferably -27 to -14, and further preferably -24 to -17. If this value is small, the feeling of flying may be lost, or the durability to cracking due to repeated impacts may deteriorate. On the other hand, if this value is large, the hitting condition may occur in which the spin amount of the ball increases and the flight distance does not increase.

[ Relationship between compression deformation amount of each coated sphere ]
If the compression deformation amount (mm) from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) of each sphere of the core and the envelope layer-coated sphere is P and Q, respectively, the value of P-Q Is preferably 0 to 0.6 mm, more preferably 0.1 to 0.5 mm, still more preferably 0.2 to 0.4 mm. If this value is small, the feel on impact may deteriorate, or the durability to cracking due to repeated impacts may deteriorate. On the other hand, if this value is large, the spin amount of the ball at a full shot increases, and the flight distance may not be achieved.

Letting Q and R be the compression deformation amounts (mm) from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) of each sphere of the envelope layer-covered sphere and the intermediate layer-covered sphere, respectively, Q- The value of R is preferably 0.1 to 0.8 mm, more preferably 0.2 to 0.7 mm, and further preferably 0.3 to 0.6 mm. If this value is small, the spin amount of the ball at the full shot may increase and the flight distance may not be achieved. On the other hand, if this value is large, the feel on impact may deteriorate, and the durability to cracking due to repeated impact may deteriorate.

Letting P and (D) be the amounts of compressive deformation (mm) from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) of each sphere of the core and the ball, respectively, P-(D) The value is preferably 1.0 to 1.7 mm, more preferably 1.1 to 1.6 mm, and further preferably 1.2 to 1.5 mm. If this value is small, the spin amount of the ball at the full shot may increase and the flight distance may not be achieved. On the other hand, if this value is large, the feeling of flying may be lost, or the durability to cracking due to repeated impact may deteriorate.

[ Initial velocity relationship of each coated sphere ]
The value of ball initial velocity-core initial velocity is preferably -0.8 to 0 m/s, more preferably -0.6 to -0.1 m/s, and further preferably -0.5 to -0.2 m/s. s. If this value is too small, the resilience of the ball as a whole may be low, or the spin rate at the time of a full shot may increase too much, resulting in a loss of flight distance. On the other hand, if this value is too large, the cover becomes hard and the durability to cracking upon repeated impact may deteriorate. Here, the above-mentioned "initial velocity" refers to the balls, the core, the intermediate layer-covered spheres described later, and the surrounding layer-covered spheres, and the initial velocity measuring device of the same method as the USGA drum rotation type initial velocity meter. Means the initial velocity of the golf ball measured by the measuring method defined in the initial velocity rule.

Ball initial velocity-The initial velocity value of the intermediate layer-coated sphere is preferably -0.4 to 0.4 m/s, more preferably -0.3 to 0.3 m/s, and further preferably -0.2 to. It is 0.1 m/s. If this value is too large, the low spin effect at the time of a full shot may be insufficient to provide a long flight distance, or the cover may become hard, resulting in poor durability to cracking when repeatedly hit. On the other hand, if the above value is too small, the cover may be softened to increase the spin on a full shot, failing to provide a flight distance, or failing to provide a feeling of flight.

The initial velocity of the intermediate layer-coated sphere-the initial velocity of the envelope layer-coated sphere is preferably 0.0 m/s or more, preferably 0.05 to 0.4 m/s, and more preferably 0.1 to 0.3 m. /S. If this value is too small, the low spin effect at the time of a full shot may not be sufficient and the flight distance may not be achieved. On the other hand, if the above value is too large, the material for the intermediate layer becomes brittle and the durability to cracking upon repeated impact may deteriorate.

A large number of dimples can be formed on the outer surface of the outermost cover. The number of dimples arranged on the cover surface is not particularly limited, but is preferably 250 or more, preferably 300 or more, more preferably 320 or more, and the upper limit is preferably 380 or less, more preferably 350. It is possible to provide not more than 340 pieces, more preferably not more than 340 pieces. If the number of dimples exceeds the above range, the trajectory of the ball becomes low, and the flight distance may decrease. On the other hand, when the number of dimples decreases, the trajectory of the ball increases and the flight distance may not be extended.

As for the shape of the dimples, one kind or a combination of two or more kinds such as a circle, various polygons, a dew drop shape, and an oval shape can be appropriately used. For example, when using circular dimples, the diameter can be about 2.5 mm or more and 6.5 mm or less, and the depth can be 0.08 mm or more and 0.30 mm or less.

The dimple occupation ratio of the dimples on the spherical surface of the golf ball, specifically, the total of the dimple areas defined by the surface edges of the plane surrounded by the edges of the dimples occupies the ball sphere area assuming that no dimples exist. The ratio (SR value) is preferably 70% or more and 90% or less from the viewpoint that aerodynamic characteristics can be sufficiently exhibited. Further, the value V _{0 obtained} by dividing the spatial volume of the dimples under the plane surrounded by the edges of each dimple by the cylindrical volume having the plane as the bottom and the maximum depth of the dimples from this bottom as the height is From the viewpoint of optimizing the trajectory of the ball, 0.35 or more and 0.80 or less is preferable. Further, the VR value occupying the ball ball volume assuming that the dimples do not exist is the total VR value formed below the plane surrounded by the edges of the dimples is 0.6% or more and 1.0% or less. Is preferred. If the value deviates from the range of each of the above numerical values, the trajectory becomes a trajectory that does not provide a good flight distance, and it may not be possible to obtain a sufficiently satisfactory flight distance.

From the viewpoint of ensuring the appearance, it is preferable to apply a clear coating on the cover surface. In the coating composition used for clear coating, it is preferable to use two types of polyester polyols as a main component and polyisocyanate as a curing agent. In this case, various organic solvents can be mixed depending on the coating conditions. Examples of such an organic solvent include aromatic solvents such as toluene, xylene and ethylbenzene, ester solvents such as ethyl acetate, butyl acetate, propylene glycol methyl ether acetate and propylene glycol methyl ether propionate, acetone and methyl ethyl ketone. , Methyl isobutyl ketone, ketone solvents such as cyclohexanone, ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, mineral spirits, etc. Petroleum hydrocarbon solvents can be used.

The hardness of the coating layer (coating layer) formed by the clear coating is Shore C hardness, preferably 40 to 80, more preferably 47 to 72, and further preferably 55 to 65. If the coating layer is too soft, the surface of the ball may be easily covered with mud during golf use. Further, if the coding layer is too hard, the coating layer may be easily peeled off when the ball is hit.

The core center hardness (Cc)-hardness of the coating layer is Shore C hardness, preferably -15 to 5, more preferably -10 to 0, and further preferably -8 to -5. If this value deviates from the above range, the spin amount of the ball at the time of full shot may increase and the flight distance may not be achieved.

The thickness of the coating layer (coating layer) is usually 9 to 22 μm, preferably 11 to 20 μm, and more preferably 13 to 18 μm. If the coating layer is thinner than the above range, the protective effect of the cover may be insufficient. On the other hand, if the coating layer is thicker than the above range, the dimple shape may not be sharp, and as a result, the flight distance may not be obtained.

The multi-piece solid golf ball of the present invention can be used for competition and complies with the Rules of Golf. The outer diameter of the ball is 42.80 mm or less and the mass is preferably 42.672 mm or less. It can be formed to 45.0 to 45.93 g.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 5, Comparative Examples 1 to 5]
Formation of Core A solid core was prepared by preparing the rubber compositions of Examples and Comparative Examples shown in Table 1 and then vulcanizing and molding under vulcanization conditions of 155° C. for 15 minutes.

The details of each component shown in Table 1 are as follows.
-Polybutadiene A: JSR, product name "BR01"
・Polybutadiene B: product name "BR51" manufactured by JSR
Zinc acrylate: "ZN-DA85S" (manufactured by Nippon Shokubai Co., Ltd.)
-Organic peroxide (1): Dicumyl peroxide, trade name "Parkmill D" (manufactured by NOF CORPORATION)-Organic peroxide (2): 1,1-di(t-butylperoxy)cyclohexane and silica Mixture with, trade name "Perhexa C-40" (NOF Corporation)
・Water: Pure water (manufactured by Seiki Pharmaceutical Co., Ltd.)
-Antiaging agent: 2,2-methylenebis(4-methyl-6-butylphenol), trade name Nocrac NS-6 (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
・Barium sulfate: Barium sulfate arsenic Varico #100 (manufactured by Hakusui Chemical Co., Ltd.)
・Zinc oxide: Product name "Triple zinc oxide" (manufactured by Sakai Chemical Industry Co., Ltd.)
・Pentachlorothiophenol zinc salt: Wako Pure Chemical Industries, Ltd.

Formation of Envelope Layer and Intermediate Layer Next, for each of Examples and Comparative Examples except for Comparative Example 5, an envelope layer was formed around the core by an injection molding method using an envelope layer material having a composition shown in Table 2. After forming, an intermediate layer was formed by an injection molding method using the intermediate layer material having the composition shown in the same table to obtain a sphere coated with the envelope layer and the intermediate layer. For Comparative Example 5, an intermediate layer was formed around the core by an injection molding method using the intermediate layer material having the composition shown in Table 2 to obtain a sphere coated with the intermediate layer.

Formation of Cover (Outermost Layer ) Next, for all the Examples and Comparative Examples, a cover (injection molding method) was used around the intermediate layer-coated spheres obtained above by using a cover material having the composition shown in Table 2. Outermost layer). At this time, a predetermined number of dimples common to all the examples and the comparative examples were formed on the surface of the cover.

The trade names of the main materials listed in the table are as follows.
"Hytrel": polyester elastomer "HPF1000" manufactured by Toray DuPont: Dupont HPF (trademark) 1000
"HPF2000": Dupont HPF (trademark) 2000
"Himilan, AM7318, AM7327, AM7329": Ionomer made by Mitsui-DuPont Polychemical "Surlyn": Ionomer made by Dupont "AN 4221C": "Nucrel" made by Mitsui-Dupont Polychemical
"Magnesium stearate": "Magnesium stearate G" manufactured by NOF
"Magnesium oxide": "Kyowamag MF-150" manufactured by Kyowa Chemical Industry Co., Ltd.
"Titanium oxide": manufactured by Sakai Chemical Industry

Formation of Coating Layer (Coating Layer) Next, in the coating composition shown in Table 3 below, the above coating is applied by an air spray gun to the surface of the cover (outermost layer) on which a large number of dimples are formed, and a coating having a thickness of 15 μm is formed. A layer-formed golf ball was produced.

As the main component polyol, a polyester polyol synthesized by the following method was used.
In a reactor equipped with a reflux condenser, a dropping funnel, a gas introduction pipe and a thermometer, 140 parts by mass of trimethylolpropane, 95 parts by mass of ethylene glycol, 157 parts by mass of adipic acid and 58 parts by mass of 1,4-cyclohexanedimethanol were added. After charging, the temperature was raised to 200 to 240° C. with stirring, and heating (reaction) was performed for 5 hours. Then, a polyester polyol having an acid value of 4, a hydroxyl value of 170, and a weight average molecular weight (Mw) of 28,000 was obtained. As the additives, that is, the water-repellent additives, all of which are commercially available products, which are silicone-based additives and stain-contamination-improving silicone additives, in which the alkyl group chain length of the fluoropolymer is 7 or less, Was added.
As the isocyanate of the curing agent, a duranate TPA-100 (NCO content: 23.1%, nonvolatile content: 100%) manufactured by Asahi Kasei, which is a nurate (isocyanurate) of hexamethylene diisocyanate (HMDI), was used. ..
Butyl acetate was used as the solvent of the main agent, and ethyl acetate and butyl acetate were used as the solvents of the curing agent. The Shore C hardness in the above table is a value obtained by forming a sheet having a thickness of 2 mm, stacking three sheets, and measuring the Shore C hardness with a Shore C hardness meter conforming to the ASTM D2240 standard.

For each golf ball obtained, the physical properties of the center and surface hardness of the core, the outer diameter of the core and each coated sphere, the thickness and material hardness of each layer, the surface hardness of each coated sphere, the initial velocity and the amount of compressive deformation at a given load. Was evaluated by the following method and is shown in Table 4.

At the temperature of the outer diameter of each of the spheres of the core, the envelope layer-covered spheres and the intermediate layer-covered spheres, 23.9±1° C., 5 arbitrary surfaces were measured, and the average value was taken as the measured value for each sphere, The average value of 10 measurements was determined.

At a temperature of a ball diameter of 23.9±1° C., 15 parts without any dimples were measured, and the average value thereof was taken as the measured value of one ball, and the average value of 10 balls was measured. ..

Amount of compressive deformation of each sphere of core, envelope layer-covered sphere, intermediate layer-covered sphere and ball Place each sphere on a hard plate and compress from initial load of 0.2 kg to final load of 5 kg Deformation amount (A), compressive deformation amount from initial load of 5 kg to final load of 30 kg (B), amount of compressive deformation from initial load of 5 kg to final load of 60 kg (C) and the amount of compressive deformation (D) from the state in which the initial load of 10 kg was applied to the state in which the final load of 130 kg was applied were measured. The above-mentioned amounts of compressive deformation are all measured values after temperature adjustment to 23.9°C. A high load compression tester manufactured by Mu Seiki Co., Ltd. was used as a measuring instrument, and the down speed of the pressure head was measured at 4.7 mm/sec.

Core hardness distribution The surface of the core is a spherical surface, and the needle of the hardness meter was set to be substantially perpendicular to the spherical surface, and the core surface hardness was measured by Shore C hardness according to ASTM D2240. The center of the core was measured by cutting the core into a hemispherical shape to make the cross-section into a flat surface and pressing a needle of a hardness meter vertically against the central portion. It is indicated by the value of Shore C hardness.

Material hardness of the envelope layer, intermediate layer and cover (Shore D hardness)
The resin material for each layer was formed into a sheet having a thickness of 2 mm and left for 2 weeks or more. Thereafter, the Shore D hardness was measured according to the ASTM D2240 standard.

Surface hardness of sphere-covered spheres, intermediate-layer-covered spheres and balls (Shore D hardness)
The measurement was performed by pressing the needle perpendicular to the surface of each sphere. The surface hardness of the ball (cover) is a measured value at a land portion where dimples are not formed on the surface of the ball. Shore D hardness was measured with a type D durometer according to the ASTM D2240 standard.

Initial velocities of the core, the envelope layer-coated sphere, the intermediate layer-coated sphere, and the ball were measured using a USGA drum rotary initial velocimeter, which is an apparatus approved by R&A, and an initial velocity measuring device of the same system. The core, the envelope layer-coated sphere, the intermediate layer-coated sphere and the ball were temperature-controlled for 3 hours or more in a 23.9±1° C. environment, and then tested in a room at a room temperature of 23.9±2° C. 5. A 250 pound (113.4 kg) head (striking mass) was used to strike the ball at a striking speed of 143.8 ft/s (43.83 m/s), and 1 dozen balls each striking 4 times. The time required to pass between 28 ft (1.91 m) was measured, and the initial speed (m/s) was calculated. This cycle was run for about 15 minutes.

The flight performance and feel of each golf ball were evaluated by the following methods. The results are shown in Table 6.

Flying performance Various clubs (W#1, UT#4, I#6) are attached to the golf hitting robot, and the flight distance when hit under the conditions shown in Table 5 below is measured. It was judged.

The club name "PHYZ" in the table above is "PHYZ Driver" (loft angle 10.5°), "PHYZ Utility U4" (loft angle 22°), "PHYZ Iron I#6" manufactured by Bridgestone Sports Co., Ltd. "It was used.

Sensory evaluation was performed by an amateur user with a hitting driver (W#1) having a head speed of 30 to 40 m/s, and both "soft feeling" and "flying feeling" were judged according to the following criteria.
(1) 12 or more out of 20 criteria for "softness" are evaluated as softness.
7 to 11 out of 20 people who were evaluated as having a soft feeling... △
6 or less out of 20 people who evaluated that there is a soft feeling ・・・ ×
(2) Criteria for "feeling of flight" 12 or more out of 20 people evaluated that there was feeling of flight...
7 to 11 out of 20 people evaluated as having a feeling of flying... △
6 or less out of 20 people evaluated as having a feeling of flight...

As shown in the results of Table 6, the golf balls of Comparative Examples 1 to 5 are inferior to the inventive products (Examples) in the following points.
In Comparative Example 1, the amount of compressive deformation (C) from the state where an initial load of 5 kg was applied to when the final load of 60 kg was applied was greater than 1.80 mm, and the compressive deformation amount (D) and the compressive deformation amount (A) were The value of the ratio (D)/(A) is greater than 20.5, and the value of the ratio (D)/(C) of the compression deformation amount (D) and the compression deformation amount (C) is 1.80. Smaller than As a result, the flight feeling is inferior and the flight distance hit by the driver (W#1) and the 6th iron (I#6) at HS=35 m/s is inferior.
In Comparative Example 2, the amount of compressive deformation (B) from the state where an initial load of 5 kg was applied to when the final load of 30 kg was applied was smaller than 0.73 mm, and the compressive deformation amount (C) was smaller than 1.55 mm. As a result, the feel of softness is inferior and the flight distance hit by the 6th iron (I#6) is inferior.
In Comparative Example 3, the compression deformation amount (B) is larger than 0.95 mm, the compression deformation amount (C) is larger than 1.80 mm, the compression deformation amount (D) and the compression deformation amount (C). Value of the ratio (D)/(C) is smaller than 1.80, and the value of the ratio (D)/(B) of the compression deformation amount (D) and the compression deformation amount (B) is 3. As a result, the flight feeling is inferior and the flight distance hit by the UT and I#6 is inferior.
In Comparative Example 4, the compression deformation amount (B) is larger than 0.95 mm, the compression deformation amount (C) is larger than 1.80 mm, the compression deformation amount (D) and the compression deformation amount (C). Value of the ratio (D)/(C) is smaller than 1.80, and the value of the ratio (D)/(B) of the compression deformation amount (D) and the compression deformation amount (B) is 3. As a result, the flight feeling is inferior and the flight distance hit by the UT and I#6 is inferior.
In Comparative Example 5, the amount of compressive deformation (B) was smaller than 0.73 mm, the amount of compressive deformation (C) was smaller than 1.55 mm, and the initial load of 10 kg was applied to the final load of 130 kg. The compression deformation amount (D) is less than 2.80 mm, the ratio (D)/(B) of the compression deformation amount (D) and the compression deformation amount (B) is less than 3.65, and the compression deformation is The value of the ratio (D)/(A) between the amount (D) and the amount of compressive deformation (A) is larger than 20.5, resulting in poor softness and W#1 (HS=35 m/s). ), the flight distance hit by UT and I#6 is inferior.

[Comparative Examples 6 to 8]
As other companies' products, "XXIO Premium 2018 model" (Sumitomo Rubber Industries, Ltd.), "Titleist VG3 2018 model" (Acushnet) and "CHROME SOFT 2018 model" (Callaway) are each compared. As Comparative Examples 7 and 8, the compression deformation amount of each golf ball of each Comparative Example was measured, and the flight performance and feel of each golf ball were measured in the same manner as in the above Examples. It was evaluated by. Table 7 shows these compression deformation amounts and ball characteristics. Comparative Example 6 is a three-piece solid solid golf ball including a single-layer core, an intermediate layer and a cover, Comparative Example 7 is a three-piece solid solid golf ball including a two-layer core and a cover, and Comparative Example 8 Is a four-piece solid golf ball having a two-layer core, an intermediate layer and a cover.

As shown in the results of Table 7, the golf balls of Comparative Examples 6 to 8 are inferior to the inventive products (Examples) in the following points.
In Comparative Example 6, the compression deformation amount (A) is larger than 0.21 mm, the compression deformation amount (B) is larger than 0.95 mm, the compression deformation amount (C) is larger than 1.80 mm, and the compression deformation is The quantity (D) is larger than 3.40 mm. Further, the ratio of the amount of compression deformation: (D)/(C) is smaller than 1.80, the ratio of the amount of compression deformation: (D)/(B) is smaller than 3.65, The ratio of deformation amount: the value of (D)/(A) is smaller than 16.0. As a result, the flight feeling is inferior and the flight distance hit with W#1 (HS=40 m/s) and I#6 is inferior.
In Comparative Example 7, the compression deformation amount (A) is larger than 0.21 mm, the compression deformation amount (B) is larger than 0.95 mm, the compression deformation amount (C) is larger than 1.80 mm, and the compression deformation is The quantity (D) is larger than 3.40 mm. Further, the ratio of the amount of compression deformation: (D)/(C) is smaller than 1.80, the ratio of the amount of compression deformation: (D)/(B) is smaller than 3.65, The ratio of deformation amount: the value of (D)/(A) is smaller than 16.0. As a result, the flight feeling is inferior and the flight distance hit by the UT is inferior.
In Comparative Example 8, the amount of compressive deformation (A) is larger than 0.21 mm, and the ratio of the amount of compressive deformation: (D)/(A) is smaller than 16.0, resulting in poor flight feeling. At the same time, the flight distance hit with W#1 (HS=40 m/s) and I#6 is inferior.

Claims (12)

A golf ball comprising a core and a cover, wherein the amount of compressive deformation (A) from the state of applying an initial load of 0.2 kg to the final load of 5 kg is 0.21 mm in the compressive deformation amount of the golf ball. The amount of compressive deformation (B) from the state where an initial load of 5 kg is applied to when the final load of 30 kg is 0.73 to 0.95 mm, and the initial load of 10 kg is applied. Letting (D) be the amount of compressive deformation up to the load of 130 kg, and (C) the amount of compressive deformation from the state of applying an initial load of 5 kg to the final load of 60 kg,
Value of (D)/(A): 16.0 to 20.5, and value of (D)/(C): 1.80 to 1.90
A golf ball that satisfies: The golf ball according to claim 1, wherein the amount of compressive deformation (C) is 1.55 to 1.80 mm. The golf ball according to claim 1, wherein the compression deformation amount (D) is 2.80 to 3.40 mm. 4. The golf according to claim 1, wherein the ratio (D)/(B) of the compression deformation amount (D) and the compression deformation amount (B) has a value of 3.65 to 4.20. ball. At least an intermediate layer is included between the core and the cover, and the structure of the golf ball is composed of three or more layers including a core, an intermediate layer and a cover. A golf ball according to the item. At least an envelope layer and an intermediate layer are included between the core and the cover, and the structure of the golf ball is composed of four or more layers including the core, the envelope layer, the intermediate layer and the cover. 5. The golf ball according to any one of 4 to 4. The following surface hardness relational expression (1)
Shore D hardness of cover surface> Shore D hardness of intermediate layer surface> Shore D hardness of envelope layer surface> Shore D hardness of core center (1)
The golf ball according to claim 6, which satisfies: The golf ball according to claim 1, wherein a hardness difference (Cs-Cc) between the center and the surface of the core is 20 or more in Shore C hardness. 9. The golf ball according to claim 1, wherein a coating layer is formed on the surface of the cover, and the material hardness of the coating layer is higher than the core center hardness (Cc). The golf ball according to any one of claims 6 to 9, which satisfies the following initial velocity relational expressions (2), (3), and (4).
−0.8 m/s≦(ball initial velocity−core initial velocity)≦0 m/s (2)
-0.4 m/s ≤ (ball initial velocity-intermediate layer-covered sphere initial velocity) ≤ 0.4 m/s
...(3)
0 m/s ≤ (initial velocity of intermediate layer-coated sphere-initial velocity of envelope layer-coated sphere) ≤ 0.4 m/s
...(4) A golf ball comprising a core and a cover, wherein the amount of compressive deformation of the golf ball from an initial load of 0.2 kg to a final load of 5 kg is (A). The amount of compressive deformation from the state of applying 5 kg to the final load of 30 kg (B), the amount of compressive deformation from the state of applying an initial load of 5 kg to the final load of 60 kg (C), the initial load When the amount of compressive deformation from a state of applying 10 kg to a final load of 130 kg is (D), the value of (C) is 1.55 to 1.80 mm and the value of (D) is 2. 80 to 3.40 mm,
Value of (D)/(A): 16.0 to 20.5, and value of (D)/(B): 3.65 to 4.20
A golf ball that satisfies: At least an envelope layer and an intermediate layer are included between the core and the cover, and the structure of the golf ball is composed of four or more layers including the core, the envelope layer, the intermediate layer and the cover. The described golf ball.

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