JP7298140B2 - Golf ball - Google Patents

Description

TECHNICAL FIELD The present invention relates to a golf ball having a core and a cover, which is intended for amateur users whose head speed is not high.

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

Various functional multi-piece solid golf balls have also been proposed in which the ball structure is multi-layered 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 Document Reference 5) discloses a multi-piece solid golf ball. The golf balls described in these publications satisfy the hardness relationship: ball surface hardness>intermediate layer surface hardness>enveloping layer surface hardness<core surface hardness. It gives performance. However, the golf ball proposed above has a compressive deformation amount from an initial load of 0.2 kg to a final load of 5 kg, and a compressive deformation from an initial load of 5 kg to a final load of 30 kg. It does not optimize the amount of compressive deformation, that is, it does not focus on the effect of ball characteristics depending on the degree of impact force applied to the golf ball. There is still room for improvement in terms of performance and good feel on impact.

JP-A-8-280845 JP 2014-132955 A JP 2015-173860 A JP 2016-16117 A JP 2016-179052 A

The present invention has been devised in view of the above circumstances, and provides excellent flight when hit by a so-called average golfer whose head speed is not so fast, and a soft and good hit with a feeling of flight on all clubs on full shots. To provide a golf ball for amateur users who have a sense of golf.

The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have found that, in a golf ball having a core and a cover, the relationship between the degree of impact force applied to the golf ball and ball characteristics such as flight and feel at impact. Specifically, regarding the amount of compressive deformation of the golf ball, the amount of compressive deformation (A) from the initial load of 0.2 kg to the final load of 5 kg, and the amount from the initial load of 5 kg to The amount of compression deformation (B) until a final load of 30 kg is applied, the amount of compression deformation (D) from the state of applying an initial load of 10 kg to the time of applying a final load of 130 kg, more preferably an initial load of 5 kg. By specifying the amount of compression deformation (C) from the state of being pulled to the time of applying a final load of 60 kg and the ratio of these deformation amounts, a golfer whose head speed is not fast can use a driver (W # 1) or an iron shot. Satisfactory flight performance can be obtained when hit with all clubs such as the above, and a hit feeling that combines a soft feel and a flight feel can be obtained with all clubs on full shots. This is what led to the golf ball of the invention.

Accordingly, the present invention provides the following golf balls.
[1] A golf ball comprising a core, a surrounding layer, an intermediate layer, and a cover, wherein a hardness difference (Cs-Cc) between the center and surface of the core is 20 or more in Shore C hardness, and the surrounding layer material hardness is 20 to 45 in Shore D hardness, material hardness of the intermediate layer is 50 to 62 in Shore D hardness, material hardness of the cover is 55 to 70, and 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)
is satisfied and the compressive deformation of the golf ball is measured after adjusting the temperature to 23.9°C using a compression tester with a pressure head down speed of 4.7 mm/sec. The amount of compressive deformation (A) from the applied state to the time of applying a final load of 5 kg is 0.21 mm or less, and the amount of compressive deformation (B) from the state of applying an initial load of 5 kg to the time of applying a final load of 30 kg. is 0.73 to 0.95 mm , the amount of compressive deformation (C) from the state where the initial load of 5 kg is applied to the final load of 60 kg is 1.55 to 1.80 mm, and the initial load is 10 kg. When the amount of compressive deformation from the state of being applied to the time of applying a final load of 130 kg is (D ) ,
(D)/(A) value: 16.0 to 20.5, and (D)/(C) value: 1.80 to 1.90
A golf ball characterized by satisfying
[ 2 ] The golf ball of [1] , wherein the compression deformation amount (D) is 2.80 to 3.40 mm.
[ 3 ] The above [1] or [2], wherein the ratio (D)/(B) of the compression deformation amount (D) to the compression deformation amount (B) is 3.65 to 4.20 Golf ball.
[ 4 ] The envelope layer has a thickness of 0.7 to 1.5 mm, the intermediate layer has a thickness of 0.7 to 1.5 mm, and the cover has a thickness of 0.6 to 1.5 mm. The golf ball according to any one of [1] to [3] above.
[ 5 ] The golf ball of any one of [1] to [4] , 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).
[ 6 ] The golf ball of any one of [1] to [5], 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 ≤ (initial velocity of ball - initial velocity of intermediate layer covered sphere) ≤ 0.4 m/s
... (3)
0 m/s ≤ (initial velocity of intermediate layer-covered sphere - initial velocity of envelope-covered sphere) ≤ 0.4 m/s
... (4)
[ 7 ] A golf ball comprising a core, a surrounding layer, an intermediate layer, and a cover, wherein a hardness difference (Cs-Cc) between the center and surface of the core is 20 or more in Shore C hardness, and the surrounding layer material hardness is 20 to 45 in Shore D hardness, material hardness of the intermediate layer is 50 to 62 in Shore D hardness, material hardness of the cover is 55 to 70, and 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)
is satisfied and the compressive deformation of the golf ball is measured after adjusting the temperature to 23.9°C using a compression tester with a pressure head down speed of 4.7 mm/sec. (A) is the amount of compressive deformation from the applied state to the time of applying a final load of 5 kg, (B) is the amount of compressive deformation from the state of applying an initial load of 5 kg to the time of applying a final load of 30 kg, and the initial load of 5 kg. When the amount of compressive deformation from the applied state to the time of applying a final load of 60 kg is (C), and the amount of compressive deformation from the state of applying an initial load of 10 kg to the time of applying a final load of 130 kg is (D), ( C) has a value of 1.55 to 1.80 mm, and (D) has a value of 2.80 to 3.40 mm,
(D)/(A) value: 16.0 to 20.5 and (D)/(B) value: 3.65 to 4.20
A golf ball characterized by satisfying

The golf ball of the present invention has excellent flight performance when hit by a golfer whose head speed is not so high, and also has a good hitting feel with a soft flight feeling, and is suitable as a golf ball for amateur golfers. be.

1 is a schematic cross-sectional view of a golf ball (four-layer structure) that is an embodiment of the present invention; FIG.

The present invention will be described in more detail below.
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 of the ball structure, and is usually formed by molding such as injection molding. Also, 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, still more preferably 35.0 mm or more, and the upper limit is preferably 37.0 mm or less, more preferably 36.5 mm or less, and further preferably 36.5 mm or less. Preferably, it is 36.0 mm or less. If the diameter of the core is too small, the spin rate increases when hit with a driver (W#1), and the target flight distance may not be obtained. On the other hand, if the diameter of the core is too large, the durability against repeated impacts may deteriorate, or the feel on impact may deteriorate.

The amount of compressive deformation (mm) when the core is loaded with an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf) 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 is preferably 7.0 mm or less, more preferably 6.0 mm or less, and still more 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 too much, resulting in poor flight or an excessively hard hitting feel. 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 will be too low and the ball will not fly, the feel on impact will be too soft, or the durability to cracking on repeated impact will be poor. can be.

The core is formed of a single layer or multiple layers of rubber material. Specifically, the rubber material for the core is mainly based on a base rubber, and is blended with a co-crosslinking agent, an organic peroxide, an inert filler, an organic sulfur compound, etc. to form a rubber composition. can be created. Polybutadiene is preferably used as the base rubber.

Commercially available polybutadiene can be used, and examples thereof include BR01, BR51, and BR730 (manufactured by JSR Corporation). Also, 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 added to the base rubber as long as the effects of the present invention are not impaired. Examples of rubber components other than polybutadiene include polybutadiene other than polybutadiene, and other diene rubbers such as styrene butadiene rubber, natural rubber, isoprene rubber, and ethylene propylene diene rubber.

Examples of co-crosslinking agents include unsaturated carboxylic acids and metal salts of unsaturated carboxylic acids. Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, and fumaric acid, with acrylic acid and methacrylic acid being particularly preferred. Although the metal salt of unsaturated carboxylic acid is not particularly limited, examples thereof include those obtained by neutralizing the above unsaturated carboxylic acid with a desired metal ion. Specific examples 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 the upper limit is usually 60 parts by mass, per 100 parts by mass of the base rubber. Below, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. If the amount is too large, the ball may become too hard, resulting in an unbearable feel on impact. If the amount is too small, the rebound may decrease.

Commercially available products can be used as the organic peroxide. For example, Permil D (manufactured by NOF Corporation), Perhexa C-40, Perhexa 3M (manufactured by NOF Corporation), Luperco 231XL (manufactured by Atochem) ) and the like can be suitably used. These may be used singly or in combination of two or more. The amount of the organic peroxide compounded is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, still more preferably 0.5 parts by mass or more, 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, still more 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, it may not be possible to obtain a suitable feel on impact, durability and resilience.

In addition, as a compounding agent to be compounded with the base rubber, an inert filler can be mentioned, and for example, zinc oxide, barium sulfate, calcium carbonate, etc. can be preferably used. These may be used individually by 1 type, and may use 2 or more types together. The amount of the inert filler compounded 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 proper mass and suitable resilience.

Furthermore, an anti-aging agent can be blended as necessary. ) made) and the like. These may be used individually by 1 type, and may use 2 or more types together.

The amount of the antioxidant compounded 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 parts by mass 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, and most preferably not more than 0.5 parts by mass. If the blending amount is too large or too small, it may not be possible to obtain suitable resilience and durability.

In addition, an organic sulfur compound may be blended into 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, Zinc salts of parachlorothiophenol, diphenylpolysulfides having 2 to 4 sulfur atoms, dibenzylpolysulfides, dibenzoylpolysulfides, dibenzothiazolylpolysulfides, dithiobenzoylpolysulfides, etc., and zinc salts of pentachlorothiophenol are particularly preferred. used for The amount of the organic sulfur compound compounded is 0 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably 0.2 parts by mass or more, with respect to 100 parts by mass of the base rubber. It is recommended to use 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. If the amount is too large, the effect of improving the resilience (especially on W#1 hits) cannot be expected any more, and the core may become too soft or the feel on impact 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 blending water (a water-containing material) directly with the core material, decomposition of organic peroxides in the core formulation can be accelerated. Further, it is known that the decomposition efficiency of the organic peroxide in the core rubber composition changes depending on the temperature, and the decomposition efficiency increases as the temperature rises above a certain temperature. If the temperature is too high, the amount of decomposed radicals will be too large, and the radicals will recombine or be inactivated. As a result, the number of radicals that effectively work for cross-linking is reduced. Here, when decomposition heat is generated by decomposition of the organic peroxide during core vulcanization, the temperature near the core surface is maintained at approximately the same temperature as that of the vulcanization mold, but the temperature near the core center is maintained on the outside. Since the decomposition heat of the organic peroxide decomposed from the mold is accumulated, the temperature becomes considerably higher than the mold temperature. When water (a material containing water) is added directly to the core, water acts to promote the decomposition of the organic peroxide, so it is possible to change the above-mentioned radical reaction between the core center and the core surface. can. That is, in the vicinity of the core center, the decomposition of the organic peroxide is further promoted, and the deactivation of radicals is further promoted, resulting in a further decrease in the amount of effective radicals. and cores with different dynamic viscoelastic properties at the center of the core can be obtained.

The water to be mixed with the core material is not particularly limited, and may be distilled water or tap water. In particular, it is preferable to use distilled water containing no impurities. be. The amount of water to be blended is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, with respect to 100 parts by mass of the base rubber, and the upper limit is preferably 5 parts by mass or less. 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, it is kneaded using a kneader such as a Banbury mixer or a roll, compression molded or injection molded using a core mold, and the temperature is 100 to 100 as a temperature sufficient for the organic peroxide or co-crosslinking agent to act. By appropriately heating the molded article under conditions of 200° C., preferably 140 to 180° C., for 10 to 40 minutes, the molded article can be cured and produced.

In addition, the core can be formed not only as a single layer but also as two layers of an inner core layer and an outer core layer. When the core is formed of two layers, an inner core layer and an outer core layer, the above-described rubber material can be used as the main material for both the inner layer core and the outer core layer. Further, the rubber material of the outer core layer covering the inner core layer may be the same as or different from the material of the inner core. Specifically, it is the same as explained 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, and 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, and further Preferably it is 60 or less. If this value is too large, the hit feeling may become hard, or the spin may increase on full shots, making it impossible to obtain the desired flight distance. On the other hand, if the above value is too small, the resilience will be low and the ball will not fly, or the durability to cracking upon repeated hitting will deteriorate. The above Shore C hardness is a hardness value measured with a Shore C hardness tester conforming to the ASTM D2240 standard.

The center hardness (Cc) of the core is preferably 26 or more, more preferably 28 or more, and still more preferably 30 or more in terms of Shore D hardness, and the upper limit is preferably 40 or less, more preferably 37. Below, more preferably 34 or less.

The surface hardness (Cs) of the core is preferably 73 or more, more preferably 77 or more, and still more preferably 79 or more in Shore C hardness, and the upper limit thereof is preferably 89 or less, more preferably 87 or less, and further Preferably it is 85 or less. Deviating from these hardnesses may lead to the same disadvantageous results as explained for the center hardness (Cc) of the core.

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

The difference between the surface hardness (Cs) of the core and the central 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. Below, more preferably 30 or less. If this value is too small, the effect of lowering the spin rate of the ball on driver shots may not be sufficient, and the flight distance may not be obtained. If the above value is too large, the initial velocity of the ball when actually hit may be low, resulting in a loss of flight distance, or the durability to cracking when hit repeatedly may be poor.

Next, the cover will be explained.
The material hardness of the cover is not particularly limited, but the Shore D hardness is preferably 55 or more, more preferably 59 or more, and still more preferably 61 or more, and the upper limit is preferably 70 or less, more preferably 68 or less. , and more preferably 65 or less. The cover surface hardness (also referred to as ball surface hardness), in Shore D hardness, is preferably 61 or more, more preferably 65 or more, and still more preferably 67 or more. It is preferably 74 or less, more preferably 71 or less. If the material hardness of the cover and the ball surface hardness are too soft, when hit with a driver (W#1), the spin rate increases and the initial velocity of the ball decreases, resulting in a loss of distance. If the above material hardness and surface hardness are too high, the durability to cracking 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, still more preferably 1.3 mm or less. If the cover is too thin, the durability to cracking due to repeated impacts may deteriorate. On the other hand, if the cover is too thick, the spin rate when hit with a driver (W#1) will be too high, resulting in a loss of distance, or the short game and putter feel will be too hard.

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

Between the core and the cover, an enveloping layer and an intermediate layer, which will be described below, can be provided. That is, the preferred ball structure of the present invention is not limited to a two-piece golf ball consisting of a core and a cover (single layer), but may be a three-piece golf ball or a four-piece golf ball. In particular, it is preferable to employ a three-layer golf ball comprising a core, an intermediate layer and a cover, or a four-layer golf ball comprising a core, a surrounding layer, an intermediate layer and a cover. For example, there is the golf ball G shown in FIG. 1. The golf ball G in FIG. It has a cover 4 covering 3 . Except for the coating layer, the cover 4 is the outermost layer in the golf ball layer structure. Each layer of the intermediate layer and the surrounding layer can be formed of 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 film layer 5 is formed on the surface of the cover 4 .

The surrounding layer is described below.
The material hardness of the envelope layer is not particularly limited, but the Shore D hardness is preferably 20 or more, more preferably 23 or more, and still more preferably 27 or more, and the upper limit is preferably 45 or less, more preferably 42. 40 or less, more preferably 40 or less. In addition, the surface hardness of the sphere obtained by coating the core with the envelope layer (envelope-layer-coated sphere) is preferably 28 or more, more preferably 31 or more, and still more preferably 35 or more in Shore D hardness. It is preferably 53 or less, more preferably 50 or less, still more preferably 48 or less. If the material hardness and surface hardness of these envelope layers are too soft, the spin rate of the ball on full shots will increase too much, resulting in a loss of flight distance or reduced durability to cracks on repeated impacts. . If the above material hardness and surface hardness are too high, the durability to cracking on repeated impacts will be poor, or the spin rate on full shots will increase, resulting in a loss of distance, especially at low head speeds, and a poor feel on impact. be.

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 still more 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 rate of the ball on a full shot may increase, resulting in a loss of flight distance.

The material of the envelope layer is not particularly limited, but various thermoplastic resin materials can be suitably used. A thermoplastic polyetherester elastomer is particularly preferred because it provides good resilience within the desired hardness range.

There is no particular limit to the amount of compressive deformation (mm) when a sphere whose core is covered with an envelope layer (envelope-layer-covered sphere) is loaded with an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf). However, it is preferably 3.4 mm or more, more preferably 3.8 mm or more, still more preferably 3.9 mm or more, and the upper limit is preferably 4.7 mm or less, more preferably 4.5 mm or less, and still more preferably 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 too much, resulting in poor flight or an excessively hard hitting feel. 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 will be too low and the ball will not fly, the feel on impact will be too soft, or the durability to cracking on repeated impact will be poor. It can get worse.

Next, the intermediate layer will be explained below.
The material hardness of the intermediate layer is not particularly limited, but the Shore D hardness is preferably 40 or more, more preferably 45 or more, and still more preferably 50 or more, and the upper limit is preferably 62 or less, more preferably 60. 58 or less, more preferably 58 or less. The surface hardness of the sphere obtained by coating the envelope-coated sphere with the intermediate layer (intermediate-layer-coated sphere) is preferably 46 or more, more preferably 51 or more, and still more preferably 56 or more in terms of Shore D hardness. is preferably 68 or less, more preferably 66 or less, and even more preferably 64 or less. If the material hardness and surface hardness of these intermediate layers are too soft, the spin rate on full shots will increase too much, resulting in a loss of flight distance or lack of flight feeling. If the above material hardness and surface hardness are too high, the durability to cracking due to repeated impacts may deteriorate, and the softness 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 the intermediate 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 intermediate layer is too thick, the spin rate of the ball on a full shot may increase, resulting in a loss of flight distance.

Known resins can be used as materials for forming the intermediate layer, and are not particularly limited. Examples of preferred materials include the following components (A) to (D),
(a-1) an olefin-unsaturated carboxylic acid binary random copolymer and/or a metal ion neutralized product of an olefin-unsaturated carboxylic acid binary random copolymer;
(a-2) Metal ion-neutralized olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer and/or olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer (A) base resin blended so that the mass ratio is 100: 0 to 0: 100,
(B) Fatty acid and/or derivative thereof having a molecular weight of 228 to 1500 for 100 parts by mass of a resin component blended with (B) a non-ionomer thermoplastic elastomer at 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 unneutralized acid groups in components (A) and (C) are blended as essential components. can be exemplified by the resin composition formed by

For the above components (A) to (D), for example, intermediate layer resin materials (A) to (D) described in JP-A-2010-253268 can be suitably employed.

A non-ionomer thermoplastic elastomer can be blended in the intermediate layer material. The amount of the non-ionomer thermoplastic elastomer to be blended is preferably 0 to 50 parts by mass per 100 parts by mass of the base resin.

Examples of the non-ionomer thermoplastic elastomers include polyolefin elastomers (including polyolefins and metallocene polyolefins), polystyrene elastomers, diene polymers, polyacrylate polymers, polyamide elastomers, polyurethane elastomers, polyester elastomers, polyacetal, and the like. can be mentioned.

Arbitrary additives can be appropriately added to the intermediate layer material depending on the application. For example, various additives such as pigments, dispersants, anti-aging 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, with respect to the total 100 parts by mass of the base resin, and the upper limit is preferably It is 10 parts by mass or less, more preferably 4 parts by mass or less.

The compressive deformation (mm) of a sphere obtained by covering an envelope-covered sphere with an intermediate layer (intermediate-layer-covered sphere) from an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf) is Although not particularly limited, it is preferably 3.3 mm or more, more preferably 3.45 mm or more, still more preferably 3.6 mm or more, and the upper limit 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 too much, resulting in poor flight or an excessively hard hitting feel. 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 will be too low and the ball will not fly, or the feel on impact will be too soft, or the durability to cracking upon repeated impact will be poor. It can get worse.

A multi-piece solid golf ball formed by stacking the layers of the core, envelope layer, intermediate layer and cover (outermost layer) described above can be manufactured by a conventional injection molding method or the like. For example, a multi-piece golf ball can be obtained by sequentially injecting an envelope layer material and an intermediate layer material around a core to obtain an intermediate layer-covered sphere and then injection molding a cover material. Alternatively, a golf ball can be produced by wrapping the coated sphere with two half-cups, which have been formed in advance into a semi-spherical shape, as the respective coating layers, and molding the coated sphere under heat and pressure.

The amount of compressive deformation (A) of the golf ball of the present invention from an initial load of 0.2 kg to a final load of 5 kg is preferably 0.21 mm or less, more preferably 0.19 mm or less. , and more preferably 0.17 mm or less. This lower limit is preferably 0.10 mm or more, more preferably 0.12 mm or more, and still more preferably 0.15 mm or more. When this value becomes small, if it is caused by the hardness of the cover, the cover may be too hard and the durability to cracking upon repeated impact may deteriorate. Also, if the decrease in the above value is due to the compression of the inner layer, the feel of the ball on a full shot may become too hard. On the other hand, when the above value increases, if it is caused by the hardness of the cover, the spin rate of the ball on a full shot may increase, resulting in a loss of flight distance. Also, if the increase in the above value is due to the compression of the inner layer, the ball loses the feel of bounce when hit on a 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 an initial load of 5 kg to a final load of 30 kg is preferably 0.73 mm or more, more preferably 0.74 mm or more. The upper limit is preferably 0.95 mm or less, more preferably 0.90 mm or less, and even more preferably 0.88 mm or less. If this value is small, the hitting feeling may become too hard when hit with a utility (UT) or an iron. On the other hand, if the above value is large, the feel of hitting the ball with a utility (UT) or an iron will be reduced, and the flight distance may not be obtained.

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

The amount of compressive deformation (D) from an initial load of 10 kg to a final load of 130 kg of the golf ball of the present invention is preferably 2.80 mm or more, more preferably 2.90 mm or more, and even more preferably 2.90 mm or more. 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 still more preferably 3.28 mm or less. If this value is too small, the spin rate of the ball will increase, resulting in poor flight or an excessively hard hitting feel. On the other hand, if the above value is too high, the resilience of the ball becomes too low, resulting in poor flight, too soft feel on impact, and poor durability to cracking upon repeated hitting.

The ratio (D)/(C) between the compression deformation amount (D) and the compression deformation amount (C) is preferably 1.80 to 1.90. If the ball is out of this range, the feel of flight becomes poor, and there may be hit conditions where the flight distance is reduced.

The ratio (D)/(B) of the compression deformation amount (D) to the compression deformation amount (B) is preferably 3.65 or more, more preferably 3.67 or more, and still more preferably 3.69 or more. On the other hand, the upper limit is preferably 4.20 or less, more preferably 4.15 or less, still more preferably 4.10 or less. If the ball is out of this range, the feel of flight becomes poor, and there may be hit conditions where the flight distance is reduced.

The ratio (D)/(A) of the compression deformation amount (D) to the compression deformation amount (A) is preferably 16.0 or more, more preferably 17.0 or more, and still more preferably 17.5 or more. On the other hand, the upper limit is preferably 20.5 or less, more preferably 20.3 or less, still more preferably 20.0 or less. If this value is out of the above range, the ball may have too much spin, or the initial speed at impact may be low, resulting in a reduced flight distance depending on the number of the club.

[ Relationship of surface hardness of each layer ]
In the present invention, the hardness relationship of each layer preferably satisfies the following formula (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 hardness of the cover surface means the surface hardness of the ball. The hardness of the surface of the intermediate layer means the surface hardness of the intermediate layer-covered sphere, and the hardness of the envelope layer surface means the surface hardness of the envelope-layer-covered sphere.
If the above hardness relationship is not satisfied, it may not be possible to obtain a good flight and a feeling of hitting that combines a soft feel and a flight feeling.

As shown in the above formula, the cover surface hardness is greater than the intermediate surface hardness. The value of cover surface hardness-intermediate layer surface hardness is preferably 1 to 14, more preferably 3 to 10, still more preferably 5 to 8 in Shore D hardness. If this value is small, the amount of spin on the ball on a full shot will increase, which may result in a loss of flight distance. On the other hand, if this value is large, the feel on impact may be poor, and the durability to cracking due to repeated impact may be poor.

As shown in the above formula, the intermediate layer surface hardness is greater than the envelope layer surface hardness. The value of intermediate layer surface hardness-surrounding layer surface hardness is preferably 10 to 28, more preferably 13 to 26, and still more preferably 15 to 24 in Shore D hardness. If this value is small, the amount of spin on the ball on a full shot will increase, which may result in a loss of flight distance. On the other hand, if this value is large, the feel on impact may be poor, and the durability to cracking due to repeated impact may be poor.

As shown in the above formula, the envelope layer surface hardness is greater than the core center hardness. The value of envelope layer surface hardness-core center hardness is preferably 3 to 23, more preferably 5 to 20, still more preferably 7 to 17 in Shore D hardness. The value of the surface hardness of the envelope layer minus the surface hardness of the core is preferably -20 to 8, more preferably -15 to 5, and still more preferably -10 to 2 in Shore D hardness. If these values are small, the spin rate of the ball on a full shot increases, which may result in a loss of distance. On the other hand, if these values are large, the feel on impact may be poor, and the durability to cracking due to repeated impact may be poor.

The value of core surface hardness - ball surface hardness is preferably -30 to -10, more preferably -27 to -14, and still more preferably -24 to -17 in Shore D hardness. If this value is too small, the feel of flight may be lost, and the durability to cracking due to repeated impacts may deteriorate. On the other hand, if this value is large, there may be hit conditions where the spin rate of the ball increases and the flight distance is reduced.

[ Relationship of compressive deformation amount of each covered sphere ]
If the amount of compressive deformation (mm) of the core and the surrounding layer covering sphere from the initial load of 98 N (10 kgf) to the final load of 1,275 N (130 kgf) is respectively set as P and Q, the value of PQ 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 be poor, and the durability to cracking due to repeated impact may be poor. On the other hand, when this value is large, the spin rate of the ball on a full shot increases, which may result in a loss of distance.

Assuming that the amount of compressive deformation (mm) of each of the envelope-covered sphere and the intermediate-layer-covered sphere when an initial load of 98 N (10 kgf) and a final load of 1,275 N (130 kgf) are applied is Q and R, respectively, Q− The value of R is preferably 0.1-0.8 mm, more preferably 0.2-0.7 mm, still more preferably 0.3-0.6 mm. If this value is small, the amount of spin on the ball on a full shot will increase, which may result in a loss of flight distance. On the other hand, if this value is large, the feel on impact may be poor, and the durability to cracking due to repeated impact may be poor.

Let P and (D) be 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 each sphere of the core and the ball, then P-(D) The value is preferably 1.0-1.7 mm, more preferably 1.1-1.6 mm, even more preferably 1.2-1.5 mm. If this value is small, the amount of spin on the ball on a full shot will increase, which may result in a loss of flight distance. On the other hand, if this value is too large, the feel of flight may be lost, and the durability to cracking due to repeated impacts may deteriorate.

[ Relationship between initial velocity of each coated sphere ]
The ball initial velocity-core initial velocity value is preferably -0.8 to 0 m/s, more preferably -0.6 to -0.1 m/s, and still more preferably -0.5 to -0.2 m/s. is s. If this value is too small, the resilience of the ball as a whole may be low, or the spin rate on a full shot may be too high, resulting in a loss of flight distance. On the other hand, if this value is too large, the cover may become hard and have poor durability to cracking upon repeated impact. Here, the above-mentioned "initial velocity" is an initial velocity measuring instrument of the same method as the USGA drum rotation type initial velocity meter for balls, cores, intermediate layer-covered spheres, and envelope layer-covered spheres, which will be described later. is the initial velocity measured by the measurement method specified in the golf ball initial velocity rule.

Ball Initial Velocity—The value of the initial velocity of the intermediate layer-covered sphere is preferably −0.4 to 0.4 m/s, more preferably −0.3 to 0.3 m/s, and still more preferably −0.2 to 0.1 m/s. If this value is too large, the effect of reducing the spin rate on full shots is insufficient, resulting in a short flight distance, and the hard cover may deteriorate durability to cracks upon repeated hitting. On the other hand, if the above value is too small, the cover becomes soft, which may result in increased spin on full shots, resulting in a loss of flight distance and loss of feel.

The initial velocity of the spheres covered with the intermediate layer - the initial velocity of the spheres covered with the surrounding layer is preferably 0.0 m/s or more, preferably 0.05 to 0.4 m/s, more preferably 0.1 to 0.3 m. /s. If this value is too small, the effect of reducing the spin rate on full shots may be insufficient, resulting in a loss of flight distance. On the other hand, if the above value is too large, the material of 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 cover, which is the outermost layer. The number of dimples arranged on the surface of the cover 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. 1 or less, more preferably 340 or less. If the number of dimples exceeds the above range, the trajectory of the ball will be low and the flight distance will be reduced. Conversely, if the number of dimples is small, the trajectory of the ball becomes high, and the flight distance may not increase.

As for the shape of the dimples, one type such as circular, various polygonal, dewdrop, and other elliptical shapes can be appropriately used, or a combination of two or more types can be used. For example, when circular dimples are used, the diameter can be about 2.5 mm or more and 6.5 mm or less, and the depth can be about 0.08 mm or more and 0.30 mm or less.

The dimple occupancy rate of the spherical surface of the golf ball, specifically, the total dimple area defined by the edge of the plane surrounded by the edges of the dimples occupies the spherical area of the ball assuming no dimples. The ratio (SR value) is desirably 70% or more and 90% or less from the viewpoint of being able to sufficiently exhibit the aerodynamic characteristics. Also, the value _V0 obtained by dividing the spatial volume of a dimple under a plane surrounded by the edges of each dimple by the volume of a cylinder whose bottom is the plane and whose height is the maximum depth of the dimple from this bottom is From the point of view of optimizing the trajectory of the ball, it is preferable to set it to 0.35 or more and 0.80 or less. Furthermore, the total dimple volume formed downward from the plane surrounded by the edges of the dimples occupies the ball volume assuming that no dimples exist, and the VR value should be 0.6% or more and 1.0% or less. is preferred. If the range of each numerical value is deviated from the range described above, the trajectory may not provide a good flight distance, and a sufficiently satisfactory flight distance may not be obtained.

It is preferable to apply a clear coating to the surface of the cover also from the viewpoint of securing the appearance. It is preferable that the coating composition used for clear coating uses two kinds of polyester polyols as main ingredients and polyisocyanate as a curing agent. In this case, various organic solvents can be mixed depending on the coating conditions. Examples of such organic solvents 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. A petroleum hydrocarbon solvent or the like can be used.

The hardness of the coating film layer (coating layer) formed by the clear coating is preferably 40 to 80, more preferably 47 to 72, further preferably 55 to 65 in Shore C hardness. If this coating layer is too soft, the surface of the ball tends to be stained with mud during golf use. Also, if the coating layer is too hard, the coating layer may easily come off when the ball is hit.

The value of the core center hardness (Cc) minus the hardness of the coating layer is preferably -15 to 5, more preferably -10 to 0, and still more preferably -8 to -5 in Shore C hardness. If this value deviates from the above range, the spin rate of the ball on a full shot increases, which may result in a loss of flight distance.

The thickness of the coating film layer (coating layer) is usually 9 to 22 μm, preferably 11 to 20 μm, 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 will not be sharp, and as a result, the flight distance may not be achieved.

The multi-piece solid golf ball of the present invention can comply with the Rules of Golf for competition use, and has an outer diameter of 42.672 mm or less, which does not pass through a ring with an inner diameter of 42.672 mm, and a mass of preferably 42.80 mm or less. It can be formed from 45.0 to 45.93 g.

EXAMPLES The present invention will be specifically described below by showing examples and comparative examples, but the present invention is not limited to the following examples.

[Examples 1 to 5, Comparative Examples 1 to 5]
core formation
After preparing the rubber compositions of Examples and Comparative Examples shown in Table 1, solid cores were produced by vulcanization molding under vulcanization conditions of 155° C. for 15 minutes.

In addition, the details of each component described in Table 1 are as follows.
・Polybutadiene A: manufactured by JSR, trade name “BR01”
・Polybutadiene B: manufactured by JSR, trade name “BR51”
・ Zinc acrylate: “ZN-DA85S” (manufactured by Nippon Shokubai Co., Ltd.)
・Organic peroxide (1): Dicumyl peroxide, trade name “Percumyl D” (manufactured by NOF Corporation) ・Organic peroxide (2): 1,1-di(t-butylperoxy)cyclohexane and silica A mixture with the product name “Perhexa C-40” (manufactured by NOF Corporation)
・Water: pure water (manufactured by Seiki Pharmaceutical Co., Ltd.)
· Anti-aging agent: 2,2-methylenebis (4-methyl-6-butylphenol), trade name Nocrack NS-6 (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
・Barium sulfate: Arsenic barium sulfate Barico #100 (manufactured by Shiramizu Chemical Industry Co., Ltd.)
・ Zinc oxide: Product name “Three kinds of zinc oxide” (manufactured by Sakai Chemical Industry Co., Ltd.)
・Pentachlorothiophenol zinc salt: manufactured by Wako Pure Chemical Industries, Ltd.

Formation of Enveloping Layer and Intermediate Layer Next, in each of the examples and comparative examples except Comparative Example 5, an enveloping layer was formed around the core by an injection molding method using the enveloping layer material blend shown in Table 2. After that, an intermediate layer was formed by an injection molding method using an intermediate layer material compounded as shown in the same table to obtain a sphere coated with the surrounding layer and the intermediate layer. For Comparative Example 5, an intermediate layer was formed around the core by an injection molding method using an intermediate layer material compounded as shown in Table 2 to obtain a sphere covered with the intermediate layer.

Formation of cover (outermost layer) Next, for all the examples and comparative examples, a cover ( outermost layer) was formed. At this time, a predetermined number of dimples common to all the examples and comparative examples were formed on the cover surface.

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

Formation of Coating Layer (Coating Layer) Next, in the formulation of the coating shown in Table 3 below, the cover (outermost layer) surface on which many dimples were formed was coated with the above coating using an air spray gun to form a coating with a thickness of 15 μm. A layered golf ball was made.

A polyester polyol synthesized by the following method was used as the main polyol.
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 placed in a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube and a thermometer. After charging, the temperature was raised to 200 to 240° C. while stirring, and the mixture was heated (reacted) for 5 hours. Thereafter, 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. Additives, i.e., water-repellent additives, are all commercially available products, and are silicone-based additives, stain-resistant silicone additives, and fluorine-based polymers having an alkyl group chain length of 7 or less. added.
As the isocyanate of the curing agent, Duranate TPA-100 (NCO content: 23.1%, non-volatile content: 100%) manufactured by Asahi Kasei Corporation, which is a nurate form (isocyanurate form) of hexamethylene diisocyanate (HMDI), was used. .
Butyl acetate was used as a solvent for the main agent, and ethyl acetate and butyl acetate were used as solvents for the curing agent. The Shore C hardness in the above table is a value measured by a Shore C hardness tester conforming to the ASTM D2240 standard after preparing three sheets having a thickness of 2 mm.

For each golf ball thus obtained, various physical properties such as center and surface hardness of the core, outer diameter of the core and each coated sphere, thickness and material hardness of each layer, surface hardness of each coated sphere, initial velocity and amount of compressive deformation under a predetermined load. was evaluated by the following method and shown in Table 4.

At a temperature of 23.9±1° C. of the outer diameter of each sphere of the core, the envelope-covered sphere, and the intermediate-layer-covered sphere, five arbitrary surfaces are measured, and the average value is taken as the measured value of one sphere, An average value of 10 measurements was obtained.

At a temperature of 23.9±1° C., the diameter of the ball was measured at 15 locations without any dimples. .

Amount of compressive deformation of core, envelope-covered sphere, intermediate-layer-covered sphere, and ball Each sphere is placed on a hard plate and compressed from an initial load of 0.2 kg to a final load of 5 kg. Amount of deformation (A), amount of compression deformation (B) from applying an initial load of 5 kg to applying a final load of 30 kg, and amount of compressive deformation from applying an initial load of 5 kg to applying a final load of 60 kg. (C), and the amount of compressive deformation (D) from when an initial load of 10 kg was applied to when a final load of 130 kg was applied were measured. In addition, all of the above amounts of compressive deformation are measured values after the temperature is adjusted to 23.9°C. A high-load compression tester manufactured by Mu Seiki Co., Ltd. was used as a measuring instrument, and the downward speed of the pressure head was measured at 4.7 mm/sec.

Core Hardness Distribution The surface of the core is spherical, and the needle of a hardness tester was set so as to be substantially perpendicular to the spherical surface, and the core surface hardness was measured in terms of Shore C hardness according to ASTM D2240. The center of the core was measured by cutting the core into a hemispherical shape, flattening the cross section, and vertically pressing the needle of the hardness tester against the central portion. It is indicated by the value of Shore C hardness.

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

Surface hardness (Shore D hardness) of envelope-covered spheres, intermediate-layer-covered spheres, and balls
Measurements were taken by pressing the needle perpendicular to the surface of each sphere. The surface hardness of the ball (cover) is the measured value of land portions on the surface of the ball where no dimples are formed. Shore D hardness was measured by a type D durometer according to ASTM D2240 standard.

The initial velocities of the core, envelope-covered sphere, intermediate-layer-covered sphere, and ball were measured using an initial velocity measuring instrument of the same type as the USGA drum rotation type initial velocity meter, which is an apparatus approved by the R&A. After the core, envelope-covered sphere, intermediate-layer-covered sphere and ball were temperature-controlled in an environment of 23.9±1° C. for 3 hours or longer, they were tested in a room at room temperature of 23.9±2° C. 5. Strike the ball with a 250 lb (113.4 kg) head (striking mass) at a striking speed of 143.8 ft/s (43.83 m/s), striking each of the dozen balls four times6. The time to pass through 28ft (1.91m) was measured and the initial speed (m/s) was calculated. This cycle was performed for about 15 minutes.

The flight performance and feel on impact of each golf ball were evaluated by the following methods. Table 6 shows the results.

Various clubs (W#1, UT#4, I#6) were attached to the golf hitting robot, and the flight distance was measured under the conditions shown in Table 5 below. Judged.

The club names "PHYZ" in the above table refer to "PHYZ Driver" (loft angle 10.5°), "PHYZ Utility U4" (loft angle 22°), and "PHYZ Iron I#6" manufactured by Bridgestone Sports. "It was used.

Sensory evaluation was carried out by an amateur user at a head speed of 30 to 40 m/s with a driver (W#1), and both "soft feel" and "flying feel" were evaluated according to the following criteria.
(1) Judgment criteria for “soft feeling”
More than 12 out of 20 people evaluated it as having a soft feeling ... ○
7 to 11 out of 20 people who evaluated it as having a soft feeling ・・・ △
Less than 6 out of 20 people who evaluated that it has a soft feeling ... ×
(2) Judgment criteria for “flying feeling”
More than 12 out of 20 people evaluated it as having a flying feel ・・・ ○
7 to 11 out of 20 people who evaluated that it has a feeling of flying ・・・ △
Less than 6 out of 20 people who evaluated that it has a feeling of flying ... ×

As shown in Table 6, the golf balls of Comparative Examples 1 to 5 are inferior to the products of the present invention (Examples) in the following points.
In Comparative Example 1, the amount of compressive deformation (C) from the state of applying an initial load of 5 kg to the time of applying a final load of 60 kg is greater than 1.80 mm, and the amount of compressive deformation (D) and the amount of compressive deformation (A) The value of the ratio (D)/(A) is greater than 20.5, and the ratio (D)/(C) of the compression deformation amount (D) to the compression deformation amount (C) is 1.80 less than As a result, the flight feeling is inferior, and the flight distance when hit with a driver (W#1) and a 6-iron (I#6) at HS=35 m/s is inferior.
In Comparative Example 2, the amount of compressive deformation (B) from the state of applying an initial load of 5 kg to the time of applying a final load of 30 kg is less than 0.73 mm, and the amount of compressive deformation (C) is less than 1.55 mm. As a result, the soft feel is inferior, and the flight distance when hit with a 6-iron (I#6) is inferior.
In Comparative Example 3, the amount of compression deformation (B) is greater than 0.95 mm, the amount of compression deformation (C) is greater than 1.80 mm, and the amount of compression deformation (D) and the amount of compression deformation (C ) is smaller than 1.80, and the ratio (D)/(B) of the amount of compression deformation (D) to the amount of compression deformation (B) is 3.0. 65, resulting in poor flight feeling and poor flight distance when hit with UT and I#6.
In Comparative Example 4, the amount of compression deformation (B) is greater than 0.95 mm, the amount of compression deformation (C) is greater than 1.80 mm, and the amount of compression deformation (D) and the amount of compression deformation (C ) is smaller than 1.80, and the ratio (D)/(B) of the amount of compression deformation (D) to the amount of compression deformation (B) is 3.0. 65, resulting in poor flight feeling and poor flight distance when hit with UT and I#6.
In Comparative Example 5, the amount of compressive deformation (B) is less than 0.73 mm, the amount of compressive deformation (C) is less than 1.55 mm, and from the state where the initial load of 10 kg is applied to the final load of 130 kg. The compressive deformation amount (D) is less than 2.80 mm, the ratio (D)/(B) of the compressive deformation amount (D) to the compressive deformation amount (B) is less than 3.65, and the compressive deformation The ratio (D)/(A) of the amount (D) to the compression deformation amount (A) is greater than 20.5. ), UT and I#6, the flight distance is inferior.

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

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

Claims (7)

A golf ball comprising a core, an envelope layer, an intermediate layer, and a cover, wherein a hardness difference (Cs-Cc) between the center and surface of the core is 20 or more in Shore C hardness, and the material hardness of the envelope layer. is 20 to 45 in Shore D hardness, the material hardness of the intermediate layer is 50 to 62 in Shore D hardness, the material hardness of the cover is 55 to 70, and 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)
is satisfied and the compressive deformation of the golf ball is measured after adjusting the temperature to 23.9°C using a compression tester with a pressure head down speed of 4.7 mm/sec. The amount of compressive deformation (A) from the applied state to the time of applying a final load of 5 kg is 0.21 mm or less, and the amount of compressive deformation (B) from the state of applying an initial load of 5 kg to the time of applying a final load of 30 kg. is 0.73 to 0.95 mm , the amount of compressive deformation (C) from the state where the initial load of 5 kg is applied to the final load of 60 kg is 1.55 to 1.80 mm, and the initial load is 10 kg. When the amount of compressive deformation from the state of being applied to the time of applying a final load of 130 kg is (D ) ,
(D)/(A) value: 16.0 to 20.5, and (D)/(C) value: 1.80 to 1.90
A golf ball characterized by satisfying 2. The golf ball of claim 1 , wherein the compression deformation amount (D) is 2.80 to 3.40 mm. 3. The golf ball according to claim 1, wherein a ratio (D)/(B) of the compression deformation amount (D) to the compression deformation amount (B) is 3.65 to 4.20. The envelope layer has a thickness of 0.7 to 1.5 mm, the intermediate layer has a thickness of 0.7 to 1.5 mm, and the cover has a thickness of 0.6 to 1.5 mm. 4. The golf ball according to any one of items 1 to 3 . The golf ball of any one of claims 1 to 4, wherein a coating layer is formed on the cover surface, and the material hardness of the coating layer is higher than the core center hardness (Cc). The golf ball of any one of claims 1 to 5 , 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 ≤ (initial velocity of ball - initial velocity of intermediate layer covered sphere) ≤ 0.4 m/s
... (3)
0 m/s ≤ (initial velocity of intermediate layer-covered sphere - initial velocity of envelope-covered sphere) ≤ 0.4 m/s
... (4) A golf ball comprising a core, an envelope layer, an intermediate layer, and a cover, wherein a hardness difference (Cs-Cc) between the center and surface of the core is 20 or more in Shore C hardness, and the material hardness of the envelope layer. is 20 to 45 in Shore D hardness, the material hardness of the intermediate layer is 50 to 62 in Shore D hardness, the material hardness of the cover is 55 to 70, and 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)
is satisfied and the compressive deformation of the golf ball is measured after adjusting the temperature to 23.9°C using a compression tester with a pressure head down speed of 4.7 mm/sec. (A) is the amount of compressive deformation from the applied state to the time of applying a final load of 5 kg, (B) is the amount of compressive deformation from the state of applying an initial load of 5 kg to the time of applying a final load of 30 kg, and the initial load of 5 kg. When the amount of compressive deformation from the applied state to the time of applying a final load of 60 kg is (C), and the amount of compressive deformation from the state of applying an initial load of 10 kg to the time of applying a final load of 130 kg is (D), ( The value of C) is 1.55 to 1.80 mm, the value of (D) is 2.80 to 3.40 mm,
(D)/(A) value: 16.0 to 20.5 and (D)/(B) value: 3.65 to 4.20
A golf ball characterized by satisfying

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