JP2022025188A - Multi-piece solid golf ball - Google Patents

Abstract

To provide a golf ball which allows a user to obtain a sufficient carry by an iron full shot, have an advantage in a short game, and obtain an excellent hitting feeling, and is excellent in durability.SOLUTION: A golf ball comprises a core, an envelope layer, an intermediate layer and a cover, in which: the core comprises a single layer or a plurality of layers and is formed from a rubber composition; the envelope layer comprises a single layer or a plurality of layers and is formed from a resin material; the intermediate layer comprises a single layer and is formed from a resin material; the cover comprises a single layer of a thickness of 1.0 mm or less and is formed from a resin material; a Shore C hardness of a core surface, a Shore C hardness of an envelope layer-covering sphere surface, a Shore C hardness of an intermediate layer-covering sphere surface, and a Shore C harness of a ball surface satisfy conditions of (the Shore C hardness of the envelope layer-covering sphere surface)>(the Shore C hardness of the core surface), and (the Shore C hardness of the intermediate layer-covering sphere surface)>(the Shore C hardness of the ball surface); and when deflection quantities upon application of a prescribed load to the core and the ball are C, B(mm), B≥3.0, and 2.5≤C-B≤4.3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multi-piece solid golf ball consisting of four or more layers including a core, a single layer or a plurality of surrounding layers, an intermediate layer and a cover.

Many ideas have been made to design the ball into a multi-layered structure, and many balls have been developed that satisfy not only professional golfers but also advanced and intermediate amateur golfers. For example, a functional multi-piece solid golf ball in which the surface hardness of each layer of the core, the surrounding layer, the intermediate layer, and the cover (outermost layer) is optimized is widespread. In addition, focusing on the core hardness distribution that occupies most of the volume of the ball, we have proposed several technologies to provide high-performance golf balls for professionals and intermediate-advanced players by designing various forms of core internal hardness. Has been done.

Examples of such technical documents include the following patent documents 1 to 15. These golf balls relate to golf balls having a multi-layer structure of four or more layers, and patents focusing on the surface hardness of each layer of the core, surrounding layer, intermediate layer and cover (outermost layer), the thickness of each layer, and the core hardness distribution. It is a document.

However, the golf ball proposed above still has room for improvement in optimizing the hardness distribution of the core and the thickness relationship with each layer. That is, even if the golf ball proposed above can maintain a good flight distance when hit by a driver (W # 1), many of them are insufficient in terms of flight distance when hit by an iron shot. In addition, among the golf balls proposed above, if an attempt is made to obtain superior flight distance performance not only when hitting a driver but also when hitting an iron, a sufficiently high spin performance is exhibited in terms of spin performance when approaching. There are some golf balls that cannot be played, are not highly game-friendly, or have a poor feel on a full shot.

Further, for a certain user group of amateur users, it may be possible to improve the game quality of golf if the flight distance performance when hitting an iron is superior to the flight distance when hitting a driver. Therefore, it is desired for the user group to propose and develop a golf ball having a high short game property while greatly improving the flight distance performance when hitting an iron and improving the feel and durability which are other characteristics. There is.

Japanese Unexamined Patent Publication No. 9-248351 Japanese Unexamined Patent Publication No. 2006-326301 Japanese Unexamined Patent Publication No. 2007-319667 Japanese Unexamined Patent Publication No. 2012-071163 Japanese Unexamined Patent Publication No. 2007-330789 Japanese Unexamined Patent Publication No. 2008-08077 Japanese Unexamined Patent Publication No. 2009-034507 JP-A-2009-095364 Japanese Unexamined Patent Publication No. 2016-101254 Japanese Unexamined Patent Publication No. 2016-116627 Japanese Unexamined Patent Publication No. 2009-095358 Japanese Unexamined Patent Publication No. 2016-101256 Japanese Unexamined Patent Publication No. 2008-149131 Japanese Unexamined Patent Publication No. 2009-095365 Japanese Unexamined Patent Publication No. 2009-095369

The present invention has been made in view of the above circumstances, and has good controllability in a short game while ensuring an increase in flight distance when hitting an iron, imparting a soft hit feeling, and durability against cracking due to repeated hits. It is an object of the present invention to provide a multi-piece solid golf ball having good properties.

As a result of diligent studies to achieve the above object, the present inventor has formed a relatively soft cover and a relatively hard intermediate layer for a golf ball including a core, a surrounding layer, an intermediate layer and a cover. Focusing on forming the surrounding layer adjacent to the inside of the intermediate layer into a single layer or a plurality of layers so as to be softer than the intermediate layer and harder than the core surface, it has been found that the problem of the present invention can be solved. That is, the core is formed of a single layer or a plurality of layers with a rubber composition, the surrounding layer is formed of a single layer or a plurality of layers with a resin material, the intermediate layer is formed of a single layer with a resin material, and the cover is made to have a thickness of 1. A single layer of 0 mm or less is formed of a resin material, and the surface hardness of the core, the surface hardness of the surrounding layer-coated sphere, the surface hardness of the intermediate layer-coated sphere, and the surface hardness of the ball are determined (the surface of the surrounding layer-coated sphere). The hardness relationship was specified so as to satisfy the conditions of (hardness)> (surface hardness of the core) and (surface hardness of the sphere coated with the intermediate layer)> (ball surface hardness), and a predetermined load was applied to the core and the ball. When the amount of deflection at the time is C and B (mm), the golf ball is designed so that B ≧ 3.0 and 2.5 ≦ CB ≦ 4.3, respectively, and the iron full shot is used. We have found that a good flight distance is obtained due to the low spin effect, a very soft and good feel is obtained, and both crack durability due to repeated hits and controllability around the green are good. It is the one that led to the ball.

In other words, the golf ball of the present invention is a spin-type golf ball having three or more cover layers, which is specialized for the flight distance of an iron full shot, and is spun in a short game and is green. Satisfy the needs of users who demand controllability around them. In addition, the golf ball of the present invention is soft and gives a good feel on all shots. Normally, it is difficult for a driver (W # 1) to hit a golf ball well, and it depends on the time when the driver (W # 1) flies or does not fly well. On the other hand, the golf ball of the present invention is a golf ball that can surely obtain a flight distance at least when hitting an iron, and is a golf ball that specializes in the flight distance of an iron full shot and is intended for such a user. ..

Therefore, the present invention provides the following multi-piece solid golf balls.
1. 1. A multi-piece solid golf ball comprising a core, an enclosing layer, an intermediate layer and a cover, wherein the core is formed of a single layer or multiple layers of a rubber composition and the enclosing layer is formed of a single layer or multiple layers of a resin material. The intermediate layer is a single layer made of a resin material, and the cover is made of a single layer having a thickness of 1.0 mm or less and made of a resin material. The shore C hardness of the surface of the sphere (surrounding layer-coated sphere), the shore C hardness of the surface of the sphere (intermediate layer-coated sphere) in which the surrounding layer-coated sphere is coated with the intermediate layer, and the shore C hardness of the surface of the ball. However, the conditions of (shore C hardness of the surface of the surrounding layer-coated sphere)> (shore C hardness of the surface of the core) and (shore C hardness of the surface of the intermediate layer-coated sphere)> (shore C hardness of the ball surface) are set. While satisfying, the amount of deflection when an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf) is applied to the core is C (mm), and the final load of the ball is from an initial load of 98 N (10 kgf). A multi-piece solid characterized in that B ≧ 3.0 and 2.5 ≦ CB ≦ 4.3 when the amount of deflection when 1,275 N (130 kgf) is loaded is B (mm). Golf ball.
2. 2. The relationship between the shore C hardness on the surface of the surrounding layer-coated sphere and the shore C hardness on the surface of the intermediate layer-coated sphere is as follows: (Surface shore C hardness of the intermediate layer-coated sphere)> (Surface shore C hardness of the surrounding layer-coated sphere). The multi-piece solid golf ball according to 1 above that satisfies the conditions.
3. 3. The multi-piece solid golf ball according to 1 or 2 above, wherein the relationship of the thickness of each layer satisfies the condition of (cover thickness) <(intermediate layer thickness) ≤ (total thickness of surrounding layer thickness).
4. The multi-piece solid golf according to any one of 1 to 3 above, wherein the ratio of the thickness of each layer satisfies the condition of (total thickness of surrounding layer thickness) / (cover thickness + intermediate layer thickness) ≧ 1.0. ball.
5. The multi-piece solid golf ball according to any one of 1 to 4 above, wherein the initial velocity of the ball is 76.8 m / s or more.
6. The multi-piece solid golf ball according to any one of 1 to 5 above, wherein the relationship between the core diameter and the ball diameter satisfies the condition of 0.65 ≤ (core diameter) / (ball diameter) ≤ 0.80.
7. Regarding the internal hardness of the core, when the shore C hardness at the center of the core is Cc, the shore C hardness on the surface of the core is Cs, and the shore C hardness at the midpoint between the core surface and the core center is Cm, (Cs-Cm). ) / (Cm-Cc) ≧ 1.1 The multi-piece solid golf ball according to any one of 1 to 6 above.
8. The multi-piece solid golf ball according to any one of 1 to 7 above, wherein the surrounding layer comprises an inner surrounding layer and an outer surrounding layer, and is formed into at least two layers.
9. The relationship between the shore C hardness of the surface hardness of each layer is as follows: (shore C hardness of the ball surface) <(shore C hardness of the surface of the intermediate layer coated sphere)> (shore C hardness of the surface of the outer surrounding layer coated sphere) ≧ The multi-piece solid golf ball according to 8 above, which satisfies the condition of (shore C hardness on the surface of the inner surrounding layer covering sphere)> (shore C hardness on the surface of the core).
10. Core volume (mm ³ ) x shore C hardness (Cm) at the midpoint between the core surface and core center is Core vh, inner surrounding layer volume (mm ³ ) x inner surrounding layer covering sphere surface hardness (shore C) Is IE vh, and when the volume of the outer surrounding layer (mm ³ ) × the surface hardness (shore C) of the outer surrounding layer covering sphere is OE vh, 1.0 ≤ (OE vh + IE vh) / Core vh ≤ 2. The multi-piece solid golf ball according to 8 or 9 above, which satisfies the condition of 3.

According to the multi-piece solid golf ball of the present invention, a good flight distance can be obtained with a low spin on an iron full shot, a very soft and good hit feeling can be obtained, crack durability due to repeated hits, and around the green. Both are good in controllability, and are particularly useful for golf users who place importance on the flight distance of iron full shots.

It is a schematic sectional drawing of the multi-piece solid golf ball (five-layer structure) of this invention. It is a top view which shows the mode (pattern) of the dimple common to each Example and each comparative example.

Hereinafter, the present invention will be described in more detail.
As shown in FIG. 1, the multi-piece solid golf ball of the present invention covers the core 1, the surrounding layer 2 covering the core, the intermediate layer 3 covering the surrounding layer, and the intermediate layer. A golf ball G having four or more layers having a cover 4 and the like. In FIG. 1, the siege layer 2 is formed into two layers, an inner siege layer 2a and an outer siege layer 2b. A large number of dimples D are usually formed on the surface of the cover 4. Further, although not particularly shown, a coating film layer is usually formed on the surface of the cover 4 by painting. The cover 4 is located on the outermost layer in the layer structure of the golf ball, except for the coating film layer. The core 1 or the surrounding layer 2 is not limited to a single layer, and may be formed into a plurality of two or more layers, but the intermediate layer 3 or the cover 4 is formed into a single layer.

The diameter of the core is preferably 24.7 mm or more, more preferably 25.7 mm or more, still more preferably 26.7 mm or more. The upper limit of this diameter is preferably 34.7 mm or less, more preferably 33.3 mm or less, still more preferably 31.7 mm or less.

The value of the core diameter / ball diameter is preferably 0.65 or more, more preferably 0.67 or more, still more preferably 0.70 or more, and the upper limit value is preferably 0.80 or less. It is preferably 0.76 or less, more preferably 0.73 or less. If this value is too small, the initial velocity of the ball may be low, the deflection hardness of the entire ball may be hard, and the spin rate at the time of a full shot may increase, making it impossible to obtain the desired flight distance. If the above value is too large, the amount of spin during an iron full shot may increase and the target flight distance may not be obtained, or the crack durability when repeatedly hit may be deteriorated.

The amount of deflection (mm) when an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf) is applied to the core is not particularly limited, but is preferably 5.0 mm or more, more preferably 5. It is 5 mm or more, more preferably 6.0 mm or more, and the upper limit value is preferably 9.0 mm or less, more preferably 8.5 mm or less, still more preferably 8.0 mm or less. If the amount of deflection of the core is too small, that is, if the core is too hard, the amount of spin of the ball may increase too much and the ball may not fly or the feel of hitting may become too hard. On the other hand, if the amount of deflection of the core is too large, that is, if the core is too soft, the repulsion of the ball becomes too low to fly, the hitting feeling becomes too soft, or the cracking durability at the time of repeated hitting deteriorates. Sometimes.

The core is obtained by vulcanizing a rubber composition containing a rubber material as a main material. The rubber composition is usually mainly composed of a base rubber, and a co-crosslinking agent, a cross-linking initiator, an inert filler, an organic sulfur compound and the like are blended therein to obtain a rubber composition.

It is preferable to use polybutadiene as the base rubber. As the type of polybutadiene, a commercially available product can be used, and examples thereof include BR01, BR51, and BR730 (manufactured by JSR Corporation). The proportion of polybudaziene 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 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.

The co-crosslinking agent is an α, β-unsaturated carboxylic acid and / or a metal salt thereof. 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 the unsaturated carboxylic acid is not particularly limited, and examples thereof include those obtained by neutralizing the unsaturated carboxylic acid with a desired metal ion. Specific examples thereof include zinc salts such as methacrylic acid and acrylic acid, magnesium salts and the like, and zinc acrylate is particularly preferably used.

The unsaturated carboxylic acid and / or a 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 usually 60 parts by mass as an upper limit with respect to 100 parts by mass of the base material rubber. Hereinafter, it is preferably blended in an amount of 50 parts by mass or less, more preferably 40 parts by mass or less. If the blending amount is too large, the feel may become too hard and the feel may be unbearable, and if the blending amount is too small, the resilience may decrease.

It is preferable to use an organic peroxide as the cross-linking initiator. Specifically, commercially available organic peroxides can be used, for example, Park Mill D (manufactured by NOF Corporation), Perhexa C-40, Perhexa 3M (manufactured by NOF Corporation), Luperco 231XL (Atchem). (Manufactured by the company) and the like can be preferably used. These may be used alone or in combination of two or more. The blending amount of the organic peroxide is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and further preferably 0.5 part by mass or more with respect to 100 parts by mass of the base material rubber. As the upper limit, 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, it may not be possible to obtain a suitable feel, durability and resilience.

As the filler, 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 blending amount of the filler can be preferably 1 part by mass or more, more preferably 3 parts by mass or more, based on 100 parts by mass of the base rubber. The upper limit of the blending amount can be preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and further preferably 100 parts by mass or less with respect to 100 parts by mass of the base rubber. If the blending amount is too large or too small, it may not be possible to obtain an appropriate mass and suitable resilience.

As the anti-aging agent, for example, commercially available products such as Nocrack NS-6, NS-30, 200, and MB (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) can be adopted. These may be used alone or in combination of two or more.

The amount of the antiaging agent to be blended is not particularly limited, but is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.0 as an upper limit with respect to 100 parts by mass of the base rubber. By mass or less, more preferably 0.7 parts by mass or less, still more preferably 0.5 parts by mass or less. If the blending amount is too large or too small, an appropriate core hardness gradient may not be obtained, and suitable resilience, durability and a low spin effect at the time of a full shot may not be obtained.

Further, the rubber composition may contain an organic sulfur compound in order to impart excellent resilience, and specifically, thiophenol, thionaphthol, thiophenol halide or a metal salt thereof may be added. More specifically, zinc salts such as pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, parachlorothiophenol, pentachlorothiophenol, and diphenylpolysulfide having a sulfur number of 2 to 4 are recommended. , Dibenzylpolysulfide, dibenzoylpolysulfide, dibenzothiazoylpolysulfide, dithiobenzoylpolysulfide and the like, and in particular, zinc salts of pentachlorothiophenol and diphenyldisulfide can be preferably used.

The organic sulfur compound is 0.05 parts by mass or more, preferably 0.07 parts by mass or more, more preferably 0.1 parts by mass or more, and the upper limit is 5 parts by mass or less, preferably 5 parts by mass or more, with respect to 100 parts by mass of the base material rubber. It is blended in an amount of 4 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. If the blending amount is too large, the hardness becomes too soft, and if the blending amount is too small, improvement in resilience cannot be expected.

The core can be produced by vulcanizing and curing a rubber composition containing each of the above components. For example, kneading is performed using a kneading machine such as a Banbury mixer or a roll, and compression molding or injection molding is performed using a core mold. The molded product can be cured and produced by appropriately heating the molded product at 200 ° C., preferably 140 to 180 ° C. for 10 to 40 minutes.

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

Next, the hardness distribution of the core will be described. The hardness of the core described below means the shore C hardness. This shore C hardness is a hardness value measured by a shore C hardness tester conforming to the ASTM D2240 standard.

The central hardness (Cc) of the core is preferably 33 or more, more preferably 38 or more, still more preferably 43 or more, and its upper limit is preferably 62 or less, more preferably 59 or less, still more preferably 54 or less. Is. If this value is too large, the feel of hitting may become hard, or the amount of spin may increase in a full shot and the target flight distance may not be obtained. On the other hand, if the above value is too small, the resilience may be low and the ball may not fly, or the cracking durability when repeatedly hit may be deteriorated.

The surface hardness (Cs) of the core is preferably 45 or more, more preferably 50 or more, still more preferably 55 or more, and the upper limit thereof is preferably 74 or less, more preferably 70 or less, still more preferably 66 or less. Is. Deviating from these hardnesses may lead to the same disadvantageous results as described in Core Hardness (Cc) above.

The hardness (Cm) of the midpoint between the core surface and the core center is preferably 37 or more, more preferably 42 or more, still more preferably 47 or more, and the upper limit thereof is preferably 66 or less, more preferably 63. Below, it is more preferably 58 or less. Deviating from these hardnesses may lead to the same disadvantageous results as described in Core Hardness (Cc) above.

The difference between the surface hardness (Cs) of the core and the center hardness (Cc) of the core is preferably 5 or more, more preferably 7 or more, still more preferably 10 or more, and the upper limit value is preferably 25 or less, more preferably 25 or less. Is 20 or less, more preferably 15 or less. If this value is too small, the amount of spin on a full shot with a driver will increase, and the desired flight distance may not be obtained. If the above value is too large, the cracking durability when repeatedly hit may be deteriorated, or the actual hitting initial velocity may be lowered and the target flight distance may not be obtained.

Regarding the internal hardness of the core, the value of (Cs-Cm) / (Cm-Cc) is preferably 1.1 or more, more preferably 1.3 or more, still more preferably 1.6 or more. The upper limit is preferably 8.0 or less, more preferably 4.0 or less. If this value is too large, the cracking durability when repeatedly hit may be deteriorated, or the actual initial velocity may be lowered and the target flight distance may not be obtained. On the other hand, if the above value becomes too small, the amount of spin at the time of a full shot increases, and the target flight distance may not be obtained.

Next, the surrounding layer will be described.
In the present invention, the surrounding layer can be formed into a single layer or a plurality of layers of two or more layers. When two or more surrounding layers are formed, the innermost layer is referred to as an inner surrounding layer, and the outermost layer is referred to as an outer surrounding layer. When there are a plurality of surrounding layers, the material hardness and surface hardness of the surrounding layer described below mean the material hardness and surface hardness of the outer surrounding layer.

The material hardness of the surrounding layer is not particularly limited, but the shore C hardness is preferably 67 or more, more preferably 70 or more, still more preferably 72 or more, and the upper limit value is preferably 90 or less, more preferably 89. Below, it is more preferably 88 or less. The shore D hardness is preferably 43 or more, more preferably 45 or more, still more preferably 47 or more, and the upper limit is preferably 60 or less, more preferably 56 or less, still more preferably 54 or less.

The surface hardness of the sphere whose core is covered with the surrounding layer is the shore C hardness, preferably 75 or more, more preferably 78 or more, still more preferably 80 or more, and the upper limit value is preferably 95 or less, more preferably 93. Below, it is more preferably 92 or less. The shore D hardness is preferably 49 or more, more preferably 51 or more, still more preferably 53 or more, and the upper limit is preferably 66 or less, more preferably 62 or less, still more preferably 60 or less.

If the material hardness and surface hardness of the surrounding layer are too softer than the above range, too much spin may be applied at the time of a full shot, or the initial velocity may be lowered and the flight distance may not be obtained. On the other hand, if the material hardness and surface hardness of the surrounding layer are too hard than the above range, the feel of hitting becomes hard, the cracking durability when repeatedly hit is deteriorated, the spin amount at the time of a full shot increases, and the flight distance May not appear.

When there are a plurality of surrounding layers, the surface hardness of the outer surrounding layer is preferably higher than the surface hardness of the inner surrounding layer, and one or more layers are interposed between the inner surrounding layer and the outer surrounding layer. In this case, it is preferable to design each layer so as to gradually increase from the inner surrounding layer to the outer surrounding layer. If this is not the case, the amount of spin at the time of a full shot may increase and the flight distance may not be obtained. Further, when the surrounding layer is designed to have a plurality of layers in this way, the flight distance may be superior due to the low spin effect at the time of a full shot as compared with the case where the surrounding layer is a single layer.

The thickness of the surrounding layer is preferably 2.0 mm or more, more preferably 2.7 mm or more, still more preferably 3.5 mm or more. On the other hand, the upper limit of the thickness of the surrounding layer is preferably 7.0 mm or less, more preferably 6.5 mm or less, and further preferably 6.0 mm or less. The thickness of the surrounding layer as used herein means the total thickness of the surrounding layer when the surrounding layer is a plurality of layers. If the siege layer is too thin, the low spin effect at the time of iron full shot may not be sufficient and the target flight distance may not be obtained. If the siege layer is too thick, the initial velocity of the entire ball will be low, the actual initial velocity will be too low, and the target flight distance may not be obtained.

Further, the thickness of the surrounding layer must satisfy the condition of (cover thickness) <(intermediate layer thickness) ≤ (total thickness of the surrounding layer) in relation to the thickness of the intermediate layer and the cover, which will be described later. Suitable. Further, regarding the ratio of the thickness of each layer, the value of (total thickness of surrounding layer thickness) / (cover thickness + intermediate layer thickness) preferably satisfies 1.0 or more, more preferably 1.5 or more. It is more preferably 1.8 or more, and the upper limit is preferably 3.5 or less, more preferably 3.0 or less, still more preferably 2.6 or less. If the above value is too large, the initial velocity may be low, the flight distance may not be obtained, or the cracking durability due to repeated impacts may be deteriorated. If the above value is too small, the low spin effect may be insufficient and the flight distance may not be obtained.

The material of the surrounding layer is not particularly limited, but known resins can be used, and examples of particularly preferable materials include the following components (a) to (c).
(A) Metal ion neutralized product of olefin-unsaturated carboxylic acid binary random copolymer and / or olefin-unsaturated carboxylic acid binary random copolymer.
(B) 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. A base resin blended so that the mass ratio is 100: 0 to 0: 100, and
(C) A resin composition in which a non-ionomer thermoplastic elastomer is blended so as to have a mass ratio of 100: 0 to 50:50 can be exemplified.

For the above components (a) to (c), for example, the resin material of the intermediate layer described in JP-A-2010-253268 can be preferably adopted.

Any additive can be appropriately added to the above resin material depending on the intended use. 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 thereof is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and preferably the upper limit with respect to 100 parts by mass of the total of the base resin. It is 10 parts by mass or less, more preferably 4 parts by mass or less.

Next, the intermediate layer will be described.
The material hardness of the intermediate layer is not particularly limited, but the shore D hardness is preferably 58 or more, more preferably 60 or more, still more preferably 63 or more, and the upper limit value is preferably 70 or less, more preferably 68. Below, it is more preferably 65 or less. The shore C hardness is preferably 87 or more, more preferably 89 or more, still more preferably 93 or more, and the upper limit is preferably 100 or less, more preferably 98 or less, still more preferably 96 or less.

The surface hardness of the sphere (intermediate layer-coated sphere) in which the surrounding layer-coated sphere is coated with the intermediate layer is the shore D hardness, preferably 64 or more, more preferably 66 or more, still more preferably 69 or more, and the upper limit. The value is preferably 76 or less, more preferably 74 or less, still more preferably 71 or less. The shore C hardness is preferably 90 or more, more preferably 93 or more, still more preferably 96 or more, and the upper limit is preferably 100 or less, more preferably 99 or less, still more preferably 98 or less.

If the material hardness and surface hardness of the above intermediate layer are too softer than the above range, too much spin may be applied at the time of a full shot, or the initial velocity may be lowered and the flight distance may not be obtained. On the other hand, if the material hardness and the surface hardness of the intermediate layer are too hard than the above range, the cracking durability at the time of repeated hitting may be deteriorated, or the hitting feeling at the time of putting or short approach may be too hard.

Further, the surface hardness of the intermediate layer-coated sphere is related to the ball surface hardness.
(Surface hardness of intermediate layer coated sphere)> (Ball surface hardness)
It is desirable to meet the conditions of. If this is not the case, the amount of spin during a full shot may increase and the flight distance may not be obtained, or the controllability during a short game may deteriorate.

The thickness of the intermediate layer is preferably 0.7 mm or more, more preferably 0.8 mm or more, still more preferably 1.0 mm or more. On the other hand, the upper limit of the thickness of the intermediate layer is preferably 1.8 mm or less, more preferably 1.4 mm or less, and further preferably 1.2 mm or less. It is preferable that the thickness of the intermediate layer is thicker than that of the cover (outermost layer) described later. If the thickness of the intermediate layer deviates from the above range or is formed thinner than the cover, the low spin effect at the time of hitting the driver (W # 1) may be insufficient and the flight distance may not be obtained. Further, if the intermediate layer is too thin, the cracking durability at the time of repeated striking and the durability at a low temperature may deteriorate.

As the material of the intermediate layer, various thermoplastic resins used as golf ball materials, particularly high neutralization type resin materials and ionomer resins containing the components (a) to (c) described in the material of the surrounding layer are adopted. It is preferable to do so.

Specific examples of the ionomer resin material include sodium-neutralized ionomer resin and zinc-neutralized ionomer resin, and one of these can be used alone or in combination of two or more.

Particularly preferable is an embodiment in which a zinc-neutralized ionomer resin and a sodium-neutralized ionomer resin are mixed and used as a main material. The blending ratio is 25/75 to 75/25, preferably 35/65 to 65/35, and more preferably 45/55 to 55/45 in the zinc neutralized type / sodium neutralized type (mass ratio). If Zn-neutralized ionomers and Na-neutralized ionomers are not included in this ratio, the repulsion will be too low to obtain the desired flight, the cracking durability during repeated impacts at room temperature will deteriorate, and the temperature will be even lower. Cracking durability at (below zero) may deteriorate.

Further, as the resin material of the intermediate layer, a high acid content ionomer resin having an acid content of 16% by mass or more among commercially available ionomer resins can be blended with a normal ionomer resin, and this blend has high resilience and low. It is possible to obtain a good flight distance when hitting the driver (W # 1) by spinning.

High acid content The content of unsaturated carboxylic acid contained in the ionomer resin (acid content is usually 16% by mass or more, preferably 17% by mass or more, more preferably 18% by mass or more, and the upper limit is preferably. It is 22% by mass or less, more preferably 21% by mass or less, still more preferably 20% by mass or less. If this value is too small, the spin may increase at the time of a full shot and the target flight distance may not be obtained. In addition, if the above value is too large, the feel of hitting may become too hard, or the cracking durability at the time of repeated hitting may deteriorate.

Further, the high acid content ionomer resin is preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 60% by mass or more with respect to 100% by mass of the resin material. If the amount of the above-mentioned high acid content ionomer resin is too small, the spin may increase when the driver (W # 1) is hit, and the flight distance may not be obtained.

Any additive can be appropriately added to the intermediate layer material depending on the intended use. 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 thereof is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and the upper limit is preferably 10 parts by mass with respect to 100 parts by mass of the base resin. Parts or less, more preferably 4 parts by mass or less.

As for the intermediate layer material, it is preferable to polish the surface of the intermediate layer in order to increase the degree of adhesion with polyurethane, which is preferably used in the cover material described later. Further, it is preferable to apply a primer (adhesive) to the surface of the intermediate layer after the polishing treatment, or to add an adhesion reinforcing material to the material.

The specific gravity of the intermediate layer material is usually less than 1.1, preferably 0.90 to 1.05, and more preferably 0.93 to 0.99. If the ball deviates from that range, the repulsion of the entire ball may become low and the flight distance may not be obtained, or the cracking durability due to repeated hits may deteriorate.

Next, the cover (outermost layer) will be described.
The material hardness of the cover is not particularly limited, but the shore D hardness is preferably 35 or more, more preferably 40 or more, further preferably 45 or more, and the upper limit value is preferably 60 or less, more preferably 60 or less. It is 55 or less, more preferably 50 or less. The shore C hardness is preferably 57 or more, more preferably 63 or more, still more preferably 70 or more, and the upper limit is preferably 89 or less, more preferably 83 or less, still more preferably 76 or less.

The surface hardness of the sphere (ball-coated sphere) in which the intermediate layer-coated sphere is covered with a cover is the shore D hardness, preferably 50 or more, more preferably 53 or more, still more preferably 56 or more, and the upper limit value is It is preferably 70 or less, more preferably 67 or less, still more preferably 64 or less. The shore C hardness is preferably 75 or more, more preferably 80 or more, still more preferably 85 or more, and the upper limit is preferably 95 or less, more preferably 92 or less, still more preferably 90 or less.

If the material hardness and ball surface hardness of these covers are too softer than the above range, the amount of spin may increase in an iron full shot and the flight distance may not be obtained. On the other hand, if the material hardness and the ball surface hardness of the cover are too hard than the above ranges, spin may not be applied by the approach or the scratch resistance may be deteriorated.

The thickness of the cover is preferably 0.3 mm or more, more preferably 0.45 mm or more, still more preferably 0.6 mm or more. On the other hand, the upper limit of the thickness of the cover is 1.0 mm or less, preferably 0.9 mm or less, and more preferably 0.85 mm or less. If the cover is too thick, the repulsion may be insufficient or the spin may increase during an iron full shot, resulting in a short flight distance. On the other hand, if the cover is too thin, the scratch resistance may be deteriorated, or the spin in the approach may not be applied, resulting in insufficient controllability.

As the material of the cover, various thermoplastic resins and thermosetting resins used in the cover material of golf balls can be used, but urethane resin is preferably used from the viewpoint of controllability and scratch resistance. can do. In particular, from the viewpoint of mass productivity of ball products, it is preferable to use mainly thermoplastic polyurethane, and more preferably, (I) thermoplastic polyurethane and (II) polyisocyanate compound as main components. It can be formed from a resin compound.

It is recommended that the total mass of the above components (I) and (II) combined is 60% or more, more preferably 70% or more, based on the total amount of the resin composition of the cover. The above-mentioned component (I) and component (II) will be described in detail below.

Regarding (I) thermoplastic polyurethane, the structure of the thermoplastic polyurethane consists of a soft segment made of a polymer polyol (polymeric glycol) which is a long-chain polyol and a hard segment made of a chain extender and a polyisocyanate compound. include. Here, as the long-chain polyol as a raw material, any of those conventionally used in the techniques related to thermoplastic polyurethane can be used, and the present invention is not particularly limited, but for example, a polyester polyol, a polyether polyol, and a polycarbonate polyol. , Polyester polycarbonate polyol, polyolefin-based polyol, conjugated diene polymerization-based polyol, castor oil-based polyol, silicone-based polyol, vinyl polymerization-based polyol, and the like. One type of these long-chain polyols may be used, or two or more types may be used in combination. Among these, a polyether polyol is preferable because it can synthesize a thermoplastic polyurethane having a high rebound resilience and excellent low temperature characteristics.

As the chain extender, those used in the conventional techniques for thermoplastic polyurethane can be preferably used. For example, a low molecular weight of 400 or less having two or more active hydrogen atoms capable of reacting with an isocyanate group in the molecule. It is preferably a molecular compound. Examples of the chain extender include 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol and the like. However, it is not limited to these. Among these, as the chain extender, an aliphatic diol having 2 to 12 carbon atoms is preferable, and 1,4-butylene glycol is more preferable.

As the polyisocyanate compound, those used in the conventional techniques for thermoplastic polyurethane can be preferably used, and there is no particular limitation. Specifically, 4,4'-diphenylmethane diisocyanate, 2,4- (or) 2,6-toluene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, naphthylene 1,5-diisocyanate, tetramethylxylene diisocyanate, hydrogenated One or more selected from the group consisting of xylylene diisocyanate, dicyclohexamethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate, and dimerate diisocyanate can be used. However, depending on the isocyanate type, it may be difficult to control the crosslinking reaction during injection molding. In the present invention, 4,4'-diphenylmethane diisocyanate, which is an aromatic diisocyanate, is most preferable from the viewpoint of the balance between the stability during production and the physical characteristics developed.

As the specific thermoplastic polyurethane of the component (I), a commercially available product can be used, and examples thereof include Pandex T8295, T8290, and T8260 (all manufactured by DC Cobestropolymer).

Although it is not an essential component, a thermoplastic elastomer other than the above-mentioned thermoplastic polyurethane can be blended with the above-mentioned components (I) and (II) as another component (III). By blending this component (III) into the resin formulation, various physical properties required for a golf ball cover material, such as further improvement of fluidity, resilience, and scratch resistance of the resin formulation, can be enhanced. ..

The composition ratios of the components (I), (II) and (III) are not particularly limited, but in order to fully exert the effects of the present invention, the mass ratios (I): (II) are used. : (III) = 100: 2 to 50: 0 to 50, more preferably (I) :( II) :( III) = 100: 2 to 30: 8 to 50 (mass ratio). It is to be.

Further, various additives other than the components constituting the above-mentioned thermoplastic polyurethane can be added to the above-mentioned resin formulation, if necessary, such as pigments, dispersants, antioxidants, and light-resistant stabilizers. , Ultraviolet absorber, mold release agent and the like can be appropriately blended.

The method for manufacturing a multi-piece solid golf ball formed by laminating each layer of the core, the surrounding layer, the intermediate layer, and the cover (outermost layer) described above can be performed by a conventional method such as a known injection molding method. For example, around the core, each material of the surrounding layer and the intermediate layer is sequentially injected with each injection molding die to obtain each coated sphere, and finally, the material of the cover which is the outermost layer is injection-molded. Allows you to obtain a multi-piece golf ball. Further, as each coating layer, a golf ball can be produced by wrapping the coated sphere with two half cups previously formed into a hemi-shell spherical shape and heat-pressing molding.

The amount of deflection (mm) when an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf) is applied to a golf ball needs to be 3.0 mm or more, preferably 3.2 mm or more. , More preferably 3.4 mm or more. On the other hand, the upper limit of the amount of deflection is preferably 4.5 mm or less, more preferably 4.2 mm or less, still more preferably 4.0 mm or less. If the amount of deflection of the golf ball is too small, that is, it is too hard, the amount of spin may increase too much and the ball may not fly or the feel of hitting may become too hard. On the other hand, if the amount of deflection is too large, that is, if the sphere is too soft, the repulsiveness of the ball becomes too low to fly, the hitting feeling becomes too soft, or the cracking durability at the time of repeated hitting deteriorates. Sometimes.

The amount of deflection when an initial load of 98N (10kgf) to a final load of 1,275N (130kgf) is applied to the core is C (mm), and the amount of deflection when a ball is loaded from an initial load of 98N (10kgf) to a final load of 1,275N. When the amount of deflection when loaded with (130 kgf) is B (mm), the value of CB is preferably 2.5 mm or more, more preferably 2.6 mm or more, still more preferably 2.7 mm or more. The upper limit is preferably 5.0 mm or less, more preferably 4.6 mm or less, still more preferably 4.3 mm or less. If the above value is too large, the initial velocity of the actual hit may be low, the flight distance may not be obtained, or the cracking durability due to repeated hits may be deteriorated. If the above value is too small, the low spin effect may be insufficient and the flight distance may not be obtained.

[ Hardness of each layer ]
In the present invention, the shore C hardness of the surface of the core, the shore C hardness of the surface of the sphere whose core is coated with the surrounding layer (surrounding layer-coated sphere), and the sphere whose surrounding layer-coated sphere is coated with the intermediate layer (intermediate). The shore C hardness of the surface of the layer-coated sphere) and the shore C hardness of the surface of the ball are
(Shore C hardness on the surface of the surrounding layer-coated sphere)> (Shore C hardness on the surface of the core) and (Shore C hardness on the surface of the intermediate layer-coated sphere)> (Shore C hardness on the surface of the ball)
It is necessary to meet the conditions of.

The value obtained by subtracting the surface hardness of the core from the surface hardness of the surrounding layer-covered sphere is greater than 0 in shore C hardness, preferably 8 or more, more preferably 15 or more, and the upper limit is preferably 50 or less. It is preferably 43 or less, more preferably 36 or less. If the above value deviates from the above numerical range, the amount of spin at the time of a full shot increases, and the target flight distance may not be obtained.

The value obtained by subtracting the ball surface hardness from the surface hardness of the intermediate layer-coated sphere is greater than 0 in shore C hardness, preferably 3 or more, more preferably 5 or more, and the upper limit value is preferably 30 or less, more preferably. Is 22 or less, more preferably 15 or less. If the above value is too small, controllability in a short game may deteriorate. On the other hand, if the above value is too large, the amount of spin in a full shot increases, and the target flight distance may not be obtained.

The value obtained by subtracting the center hardness of the core from the surface hardness of the surrounding layer-covered sphere is preferably 29 or more, more preferably 32 or more, still more preferably 35 or more in shore C hardness, and the upper limit value is It is preferably 55 or less, more preferably 50 or less, still more preferably 45 or less. If the above value is too large, the cracking durability when repeatedly hit may be deteriorated, or the actual hitting initial velocity may be lowered and the target flight distance may not be obtained. On the other hand, if the above value becomes too small, the amount of spin at the time of a full shot increases, and the target flight distance may not be obtained.

The value obtained by subtracting the surface hardness of the surrounding layer-coated sphere from the surface hardness of the intermediate layer-coated sphere is preferably greater than 0 in shore C hardness, more preferably 4 or more, still more preferably 8 or more, and the upper limit value is It is preferably 28 or less, more preferably 22 or less, and even more preferably 16 or less. If the above value deviates from the above numerical range, the amount of spin at the time of a full shot increases, and the target flight distance may not be obtained.

The value obtained by subtracting the center hardness of the core from the surface hardness of the intermediate layer-coated sphere is preferably 33 or more in shore C hardness, more preferably 38 or more, still more preferably 43 or more, and the upper limit value is preferable. Is 65 or less, more preferably 60 or less, still more preferably 55 or less. If the above value is too large, the cracking durability when repeatedly hit may be deteriorated, or the actual hitting initial velocity may be lowered and the target flight distance may not be obtained. On the other hand, if the above value becomes too small, the amount of spin at the time of a full shot increases, and the target flight distance may not be obtained.

[Relationship between core and surrounding layer volume and hardness]
Core volume (mm ³ ) x shore C hardness (Cm) at the midpoint between the core surface and core center is Core vh, inner surrounding layer volume (mm ³ ) x inner surrounding layer covering sphere surface hardness (shore C) Is IE vh, and the volume of the outer surrounding layer (mm ³ ) × the surface hardness (shore C) of the outer surrounding layer covering sphere is OE vh, the value of (OE vh + IE vh) / Core vh is 1.0. The above is preferable, more preferably 1.2 or more, still more preferably 1.4 or more, and the upper limit value is preferably 2.3 or less, more preferably 2.1 or less, still more preferably 1. It is 9 or less. If the above value is too large, the initial velocity of the actual hit may be low, the flight distance may not be obtained, or the cracking durability due to repeated hits may be deteriorated. On the other hand, if the above value is too small, the low spin effect may be insufficient and the flight distance may not be obtained.

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 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. The number or less, more preferably 340 or less, can be provided. If the number of dimples exceeds the above range, the trajectory of the ball becomes low and the flight distance may decrease. On the contrary, when the number of dimples is small, the trajectory of the ball becomes high and the flight distance may not be extended.

As for the shape of the dimples, one type or a combination of two or more types such as a circular shape, various polygonal shapes, a dewdrop shape, and an elliptical shape can be appropriately used. For example, when a circular dimple is used, 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 occupancy of the dimples on the sphere of the golf ball, specifically the total dimple area defined by the surface edge of the plane surrounded by the edges of the dimples, occupies the ball area assuming no dimples. The ratio (SR value) is preferably 70% or more and 90% or less from the viewpoint of sufficiently exhibiting aerodynamic characteristics. Further, the value V ₀ obtained by dividing the space volume of the dimples under the plane surrounded by the edges of each dimple by the volume of a cylinder having the plane as the bottom surface and the maximum depth of the dimples from the bottom surface as the height is From the viewpoint of optimizing the trajectory of the ball, it is preferably 0.35 or more and 0.80 or less. Furthermore, the VR value of the total volume of dimples formed downward from the plane surrounded by the edges of the dimples to the volume of the ball ball assuming that the dimples do not exist shall be 0.6% or more and 1.0% or less. Is preferable. If it deviates from the range of each of the above-mentioned numerical values, the trajectory may not be able to obtain a good flight distance, and a sufficiently satisfactory flight distance may not be obtained.

A coating film layer (coating layer) can be formed on the cover surface. This coating layer can be coated with various paints, and as the paint, it is necessary to withstand the harsh usage conditions of golf balls, so it is for paints containing urethane paint composed of polyol and polyisocyanate as the main component. It is preferable to use the composition.

Examples of the polyol component include acrylic polyols and polyester polyols. It should be noted that these polyols contain a modified form of the polyol, and other polyols can be added in order to further improve workability.

As the polyol component, it is preferable to use two kinds of polyester polyols in combination. In this case, assuming that the two types of polyester polyols are the component (a) and the component (b), as the polyester polyol of the component (a), a polyester polyol having a cyclic structure introduced into the resin skeleton can be adopted, for example. , Cyclohexanedimethanol and the like, and examples thereof include polyester polyols obtained by polycondensation of a polyol having an alicyclic structure with polybasic acid, or polycondensation of a polyol having an alicyclic structure with diols or triol and polybasic acid. .. On the other hand, as the polyester polyol of the component (b), a polyester polyol having a multi-branched structure can be adopted, and examples thereof include a polyester polyol having a branched structure such as "NIPPOLAN 800" manufactured by Tosoh Corporation.

On the other hand, the polyisocyanate is not particularly limited and is a commonly used aromatic, aliphatic, alicyclic or the like polyisocyanate. Specifically, it is a tolylene diisocyanate, a diphenylmethane diisocyanate, or a xylylene diisocyanate. , Tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 1,4-cyclohexylene diisocyanate, naphthalene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexammethane diisocyanate, 1-isocyanato-3,3,5-trimethyl-4-isosia Examples thereof include natomethylcyclohexane. These can be used alone or in combination.

Various organic solvents can be mixed with the coating composition 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. , Methylisobutylketone, ketone solvent such as cyclohexanone, ether solvent such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, alicyclic hydrocarbon solvent such as cyclohexane, methylcyclohexane, ethylcyclohexane, mineral spirit and the like. Petroleum hydrocarbon solvents etc. can be used.

The thickness of the coating film layer made of the above coating composition is not particularly limited, but is usually 5 to 40 μm, preferably 10 to 20 μm. The thickness of the coating film layer referred to here means the average thickness of the coating film measured at three points in total, that is, the center of the dimples and the two positions between the center of the dimples and the dimple edges.

In the present invention, the elastic work recovery rate of the coating film layer made of the above coating composition needs to be 60% or more, preferably 80% or more. When the elastic work recovery rate of the coating film layer is within the above range, the coating film layer has a high elastic force, so that the self-repairing function is high and the wear resistance is very excellent. In addition, various performances of the golf ball coated with the above-mentioned coating composition can be improved. The above-mentioned method for measuring the elastic work recovery rate is as follows.

Elastic work recovery rate is an ultra-fine hardness test method that controls the indentation load on the order of micronewton (μN) and tracks the indenter depth at the time of indentation with an accuracy of nanometer (nm). It is one of the parameters of the nanoindentation method for evaluating physical properties. With the conventional method, only the size of the deformation mark (plastic deformation mark) corresponding to the maximum load can be measured, but with the nanoindentation method, the relationship between the indentation load and the indentation depth is measured automatically and continuously. Can be obtained. Therefore, it is considered that the physical properties of the coating film layer can be evaluated with high accuracy without individual differences as in the case of visually measuring the deformation marks with an optical microscope as in the conventional case. Since the coating film layer on the ball surface is greatly affected by the impact of the driver and various clubs, and the influence of the coating film layer on the physical characteristics of the golf ball is not small, the coating film layer is measured by the ultra-fine hardness test method. However, performing with higher accuracy than before is a very effective evaluation method.

The hardness of the coating film layer is preferably 40 or more, more preferably 60 or more, and the upper limit is preferably 95 or less, more preferably 85 or less. The shore M hardness is based on ASTM D2240. The hardness of the coating film layer is preferably 40 or more, more preferably 50 or more, in terms of shore C hardness. The upper limit is preferably 80 or less, and more preferably 70 or less. The shore C hardness is based on ASTM D2240. If the coating film layer is too high above the hardness range, the coating film becomes brittle when repeatedly hit, and the cover layer may not be protected. If the coating film layer is too small than the above hardness range, the ball surface is easily scratched when it hits a hard object, which is not preferable.

When using the above paint composition, the paint composition of the present invention is adjusted at the time of painting on a golf ball manufactured by a known method, applied to the surface by adopting a normal painting process, and dried. A coating film layer can be formed on the surface of the ball. In this case, as the coating method, a spray coating method, an electrostatic coating method, a dipping method and the like can be preferably adopted, and there is no particular limitation.

The multi-piece solid golf ball of the present invention can comply with the Rules of Golf for competition, the outer diameter of the ball is a size that does not pass through a ring having an inner diameter of 42.672 mm, and the mass is preferably 45.0. It can be formed to ~ 45.93 g.

The initial velocity of the golf ball based on the R & A golf rule is usually 76.8 m / s or more, preferably 77.0 m / s or more, more preferably 77.1 m / s or more, and the upper limit is set as an upper limit. It is 77.724 m / s or less. If this initial velocity value exceeds 77.724 m / s, it will be out of the official rule. On the other hand, if the above initial velocity value is too low, the flight distance on a full shot may not be obtained.

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 4, Comparative Examples 1 to 8]
Core formation
After preparing the rubber compositions of each Example and Comparative Example shown in Table 1, a solid core was prepared by vulcanization molding under the vulcanization conditions of each example shown in Table 1.

However, for Examples 1 and 2 and Comparative Examples 7 and 8, cores are prepared based on the formulation shown in Table 1 in the same manner as described above.

The details of each component shown in Table 1 are as follows.
-Polybutadiene: JSR, product name "BR730"
-Zinc acrylate: "ZN-DA85S" (manufactured by Nippon Shokubai)
-Organic peroxide: A mixture of 1,1-di (t-butylperoxy) cyclohexane and silica, trade name "Perhexa C-40" (manufactured by NOF CORPORATION)
-Zinc stearate: Product name "Zinc stearate G" (manufactured by NOF CORPORATION)
-Anti-aging agent: 2,2-methylenebis (4-methyl-6-butylphenol), trade name "Nocrack NS-6" (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
-Zinc oxide: Product name "Three types of zinc oxide" (manufactured by Sakai Chemical Industry Co., Ltd.)
・ Pentachlorothiophenol zinc salt: manufactured by Wako Pure Chemical Industries, Ltd.

Envelopment layer (inside / outside)
Next, for each example and each comparative example except Comparative Examples 4 to 6, the No. 1 shown in Table 2 was placed around the core. An inner surrounding layer was formed by an injection molding method using the inner surrounding layer material of the formulation of No. 1, and then No. 1 shown in the same table. 1, No. 2 or No. An outer siege layer was formed by an injection molding method using the outer siege layer material of the formulation of 3. For Comparative Examples 4 to 6, No. 1 in Table 2. 1 or No. A single siege layer (detailed in the "Outer Siege Layer" column in the table) was formed around the core by injection molding using the materials of the formulation of 3.

However, for Examples 1 and 2 and Comparative Examples 7 and 8, a surrounding layer is prepared based on the formulation shown in Table 2 in the same manner as described above.

Formation of Intermediate Layer and Cover (Outermost Layer) Next, for all Examples and Comparative Examples, No. 1 of the formulations shown in Table 2 was formed around the surrounding layer-coated spheres obtained above. 4 or No. An intermediate layer was formed by an injection molding method using the intermediate layer material having the composition of 5. Next, around the intermediate layer-coated spheres of each of the above examples, No. 1 of the formulations shown in Table 2 was added. 6 or No. A cover (outermost layer) was formed by an injection molding method using the cover material having the composition of 7. At this time, a large number of predetermined dimples common to all the examples and comparative examples were formed on the cover surface.

However, for Examples 1 and 2 and Comparative Examples 7 and 8, the intermediate layer and the cover are prepared based on the formulation shown in Table 2 in the same manner as described above.

The product names of the main materials listed in the table are as follows.
"HPF1000""HPF2000" (Trademark) "HPF" manufactured by THE DOW CHEMICAL COMPANY
"Himiran 1605""Himiran1557""Himiran1706" Ionomer "Sarrin 8120" manufactured by Mitsui Dow Polychemical Co., Ltd. Ionomer "Dynaron 6100P" manufactured by THE DOW CHEMICAL COMPANY Hydrated polymer "Behenic acid" NOF "NAA222-S" manufactured by the company (designated beads)
"Calcium hydroxide""CLS-B" manufactured by Shiraishi Kogyo Co., Ltd.
"Trimethylolpropane" Tokyo Chemical Industry Co., Ltd. "TPU (1)""TPU(2)" DIC Cobestropolymer Co., Ltd. trade name "Pandex", ether type thermoplastic polyurethane

Eight kinds of circular dimples are used as dimples common to all the examples and comparative examples, the details thereof are shown in Table 3 below, and the arrangement mode thereof is as shown in FIG. FIG. 2A shows a plan view of the dimples, and FIG. 2B shows a side view thereof.

Definition of dimples <br /> Edge: Highest point in the cross section passing through the center of the dimples Diameter: Diameter of the plane surrounded by the edges of the dimples Depth: Maximum depth of the dimples from the plane surrounded by the edges of the dimples SR: The ratio of the total dimple area defined in the plane surrounded by the edges of the dimples to the ball ball area assuming that the dimples do not exist. Ratio of dimple volume to the volume of a cylinder with the same diameter as the dimple VR: The total volume of dimples formed downward from the plane surrounded by the edges of the dimples is the ball ball volume assuming that the dimples are not present.

Formation of paint layer (coating layer) Next, as the paint composition common to all the examples and comparative examples, the paint compositions shown in Table 4 below were used, and a large number of the paint compositions were formed on the surface of the cover (outermost layer). The above paint was applied with an air spray gun to produce a golf ball having a paint layer having a thickness of 15 μm.
However, in Examples 1 and 2 and Comparative Examples 7 and 8, the above paint is applied to produce a golf ball having a paint layer having a thickness of 15 μm formed in the same manner as described above.

[Synthesis example of polyester polyol (A)]
A reactor equipped with a reflux condenser, a dropping funnel, a gas introduction tube and a thermometer was provided with 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. The temperature was raised to 200 to 240 ° C. with stirring, and the mixture was heated (reacted) for 5 hours. Then, a "polyester polyol (A)" having an acid value of 4, a hydroxyl value of 170 and a weight average molecular weight (Mw) of 28,000 was obtained.
Next, the synthesized polyester polyol (A) described above was dissolved in butyl acetate to prepare a varnish having a non-volatile content of 70% by mass.

The coating composition "C" in Table 4 contains "polyester polyol (B)" (saturated aliphatic polyester polyol "NIPPOLAN 800" manufactured by Toso Co., Ltd., weight average molecular weight (weight average molecular weight) with respect to 23 parts by mass of the polyester polyol solution. Mw) 1,000, solid content 100%) was mixed with 15 parts by mass and an organic solvent to prepare a main agent. This mixture had a non-volatile content of 38.0% by weight.

Elastic work recovery rate The elastic work recovery rate of the paint is measured using a coating film sheet having a thickness of 50 μm. As the measuring device, an ultra-micro hardness tester "ENT-2100" manufactured by Elionix Inc. is used, and the measurement conditions are as follows.
・ Indenter: Berkovich indenter (Material: Diamond, Angle α: 65.03 °)
・ Load F: 0.2mN
・ Loading time: 10 seconds ・ Holding time: 1 second ・ Unloading time: 10 seconds Based on the pushing work amount _Welast (Nm) and the mechanical pushing work amount W _total (Nm) due to the return deformation of the coating film. The elastic work recovery rate is calculated by the following formula.
Elastic work recovery rate = _{We last} / W _total x 100 (%)

Shore C hardness and Shore M hardness For the Shore C hardness and Shore M hardness in Table 3 above, prepare a sheet with a thickness of 2 mm, stack three sheets, and use an ASTM D2240 standard-compliant Shore C hardness tester and Shore M hardness as test pieces. Each was measured using a meter.

For each golf ball obtained, various physical properties such as the internal hardness of the core, the outer diameter of the core and each coated sphere, the thickness and material hardness of each layer, and the surface hardness of each coated sphere were evaluated by the following methods, and Table 5 And shown in Table 6.

Measure 5 points on any surface at a temperature of 23.9 ± 1 ° C. on the outer diameter of each sphere of the core, (inner / outer) surrounding layer-coated sphere, and intermediate layer-coated sphere, and measure the average value of each sphere. The average value was obtained when the number of measured pieces was 10.

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

The core, the coated sphere of each layer and the amount of deflection of the ball The core, the coated sphere of each layer or the target coated sphere of the ball is placed on a hard plate, and the initial load of 98 N (10 kgf) is applied to the final load of 1275 N (130 kgf). Measure the amount of deflection when you do. The amount of deflection is a measured value after the temperature is adjusted to 23.9 ° C. The pressurizing speed of the core, the coated sphere of each layer, or the head for compressing the ball is 10 mm / s.

Core hardness distribution The surface of the core is a spherical surface, but the needle of the hardness tester was set on the spherical surface so as to be substantially vertical, and the core surface hardness was measured by Shore C hardness according to ASTM D2240. An automatic rubber hardness tester "P2" manufactured by Polymer Meter Co., Ltd. equipped with a Shore C type hardness tester is used for measuring the hardness. Read the maximum hardness value. All measurements are made in an environment of 23 ± 2 ° C. Regarding the cross-sectional hardness at a predetermined position of each core, which is the center hardness Cc of the core, the surface hardness Cs, and the midpoint hardness Cm between the center and the surface of the core, the core is cut into a hemispherical shape and the cross section is made flat to make the hardness at the measurement portion. The measurement was performed by pressing the needle of the meter vertically. It is indicated by the value of Shore C hardness.

(Inner / outer) Material hardness of surrounding layer, intermediate layer and cover (Shore C hardness, Shore D hardness)
The resin material of each layer was formed into a sheet having a thickness of 2 mm, and left at a temperature of 23 ± 2 ° C. for 2 weeks. At the time of measurement, three sheets are overlapped. Shore C hardness and Shore D hardness were measured with a Shore C hardness tester and a Shore D hardness tester conforming to the ASTM D2240 standard, respectively. For the measurement of hardness, an automatic rubber hardness tester "P2" manufactured by Polymer Meter Co., Ltd. equipped with a Shore C type hardness tester or a Shore D type hardness tester is used. Read the maximum hardness value.

(Inner / outer) Surface hardness of surrounding layer-coated sphere, intermediate layer-coated sphere, and ball sphere (shore C hardness, shore D hardness)
The measurement was performed by pressing the needle so that it was perpendicular to the surface of each sphere. The surface hardness of the ball (cover) is a measured value in the land area where dimples are not formed on the surface of the ball. Shore C hardness and Shore D hardness were measured with a Shore C hardness tester and a Shore D hardness tester conforming to the ASTM D2240 standard, respectively. For the measurement of hardness, an automatic rubber hardness tester "P2" manufactured by Polymer Meter Co., Ltd. equipped with a Shore C type hardness tester or a Shore D type hardness tester is used. Read the maximum hardness value.

The measurement was performed using an initial velocity measuring device of the same type as the drum rotation type initial velocity meter of USGA, which is a device approved by the ball initial velocity R & A. The balls were temperature adjusted in an environment of 23.9 ± 1 ° C. for 3 hours or more, and then tested in a room at room temperature of 23.9 ± 2 ° C. 6. Hit the ball with a 250-pound (113.4 kg) head (striking mass) at a hitting speed of 143.8 ft / s (43.83 m / s) and hit a dozen balls four times each. The time to pass between 28ft (1.91m) was measured, and the initial speed (m / s) was calculated. This cycle was performed in about 15 minutes.

The flight performance (I # 6) of each golf ball, the amount of spin at the time of approach, the feel of hitting, and the durability due to repeated hits are evaluated by the following methods. The results are shown in Table 7.

Flying performance (I # 6)
An iron (I # 6) was attached to a golf hitting robot, and the flight distance when hitting at a head speed of 44 m / s was measured and judged according to the following criteria. The club used "TourB X-CB" (I # 6) manufactured by Bridgestone Sports. Similarly, the spin amount was measured by the initial condition measuring device for the ball immediately after being hit.
<criterion>
Total flight distance 179.0m or more ・ ・ ・ ○
Total flight distance less than 179.0m ・ ・ ・ ×

Evaluation of Spin Amount at Approach The judgment was made based on the amount of spin when a golf hitting robot was hit with a sand wedge (SW) at a head speed (HS) of 20 m / s. Similarly, the spin amount was measured by the initial condition measuring device for the ball immediately after being hit. As the sand wedge (SW), "TourB XW-1" (SW) manufactured by Bridgestone Sports Co., Ltd. was used.
<criterion>
Spin amount is 5900 rpm or more ... ○
Spin amount is less than 5900 rpm ・ ・ ・ ×

Hit feeling An amateur golfer with a handicap of 15 to 25 evaluates the hit feeling when making a full shot with an iron (I # 6) according to the following criteria.
<criterion>
The number of people who evaluated it as very soft and good hitting feeling is 15 out of 20 people ... ○
The number of people who evaluated it as soft and good hitting was 10 or more and 14 or less out of 20 ... △
The number of people who evaluated it as soft and good hitting feeling is 9 out of 20 people ... ×

Cracking durability due to repeated hits A driver (W # 1) was attached to a golf hitting robot, and a ball with a measured number of N = 10 was repeatedly hit at a head speed of 45 m / s, and the judgment was made according to the following criteria.
<criterion>
Using 10 balls, count the number of hits when each ball starts to crack, select 3 balls with the least number of hits, and use the average value of the number of cracks of the 3 balls as the "cracking" of each example. It was evaluated as "number of times". The number of cracks in Example 3 was set to 100 as an index.
Index 90 or more ・ ・ ・ 〇Index less than 90 ・ ・ ・ ×

As shown in the results of Table 7, the golf balls of Comparative Examples 1 to 8 are inferior to the product of the present invention (Example) in the following points.
In Comparative Example 1, the value of (ball deflection amount)-(core deflection amount) is larger than 4.3 mm, and as a result, the cracking durability due to repeated impact is not good.
In Comparative Example 2, the value of (ball deflection amount)-(core deflection amount) is larger than 4.3 mm, and as a result, the cracking durability due to repeated hitting is not good, the flight distance of the iron is inferior, and the flight distance of the iron is inferior. It is hard to say that the feel of hitting is also good.
In Comparative Example 3, the ball deflection amount is smaller than 3.0 mm, and the value of (ball deflection amount)-(core deflection amount) is smaller than 4.3 mm, and as a result, the feel of hitting is not good.
In Comparative Example 4, the ball deflection amount is smaller than 3.0 mm, and the value of (ball deflection amount)-(core deflection amount) is smaller than 4.3 mm. Is not good.
In Comparative Example 5, the ball deflection amount is smaller than 3.0 mm, and the value of (ball deflection amount)-(core deflection amount) is smaller than 4.3 mm, and as a result, the flight distance of the iron is inferior and the feel at impact is reduced. Is not good.
In Comparative Example 6, the ball deflection amount is smaller than 3.0 mm, and the value of (ball deflection amount)-(core deflection amount) is smaller than 4.3 mm, and as a result, the flight distance of the iron is inferior and the feel at impact is reduced. Is not good.
In Comparative Example 7, the ball surface hardness is larger than the intermediate layer surface hardness, and as a result, the spin amount at the time of hitting the iron increases, the flight distance is inferior, and the spin amount in the approach decreases.
In Comparative Example 8, the thickness of the cover (outermost layer) is larger than 1.0 mm, and as a result, the spin amount at the time of hitting the iron is increased, the actual hitting initial velocity is lowered, and the flight distance is inferior.

Claims (10)

A multi-piece solid golf ball comprising a core, an enclosing layer, an intermediate layer and a cover, wherein the core is formed of a single layer or multiple layers of a rubber composition and the enclosing layer is formed of a single layer or multiple layers of a resin material. The intermediate layer is a single layer made of a resin material, and the cover is made of a single layer having a thickness of 1.0 mm or less and made of a resin material. The shore C hardness of the surface of the sphere (surrounding layer-coated sphere), the shore C hardness of the surface of the sphere (intermediate layer-coated sphere) in which the surrounding layer-coated sphere is coated with the intermediate layer, and the shore C hardness of the surface of the ball. However, the conditions of (shore C hardness of the surface of the surrounding layer-coated sphere)> (shore C hardness of the surface of the core) and (shore C hardness of the surface of the intermediate layer-coated sphere)> (shore C hardness of the ball surface) are set. While satisfying, the amount of deflection when an initial load of 98 N (10 kgf) to a final load of 1,275 N (130 kgf) is applied to the core is C (mm), and the final load of the ball is from an initial load of 98 N (10 kgf). A multi-piece solid characterized in that B ≧ 3.0 and 2.5 ≦ CB ≦ 4.3 when the amount of deflection when 1,275 N (130 kgf) is loaded is B (mm). Golf ball. The relationship between the shore C hardness on the surface of the surrounding layer-coated sphere and the shore C hardness on the surface of the intermediate layer-coated sphere is as follows: (Surface shore C hardness of the intermediate layer-coated sphere)> (Surface shore C hardness of the surrounding layer-coated sphere). The multi-piece solid golf ball according to claim 1, which satisfies the conditions. The multi-piece solid golf ball according to claim 1 or 2, wherein the relationship of the thickness of each layer satisfies the condition of (cover thickness) <(intermediate layer thickness) ≤ (total thickness of surrounding layer thickness). The multi-piece according to any one of claims 1 to 3, wherein the ratio of the thickness of each layer satisfies the condition of (total thickness of surrounding layer thickness) / (cover thickness + intermediate layer thickness) ≥ 1.0. Solid golf ball. The multi-piece solid golf ball according to any one of claims 1 to 4, wherein the initial velocity of the ball is 76.8 m / s or more. The multi-piece solid golf ball according to any one of claims 1 to 5, wherein the relationship between the core diameter and the ball diameter satisfies the condition of 0.65 ≤ (core diameter) / (ball diameter) ≤ 0.80. Regarding the internal hardness of the core, when the shore C hardness at the center of the core is Cc, the shore C hardness on the surface of the core is Cs, and the shore C hardness at the midpoint between the core surface and the core center is Cm, (Cs-Cm). ) / (Cm-Cc) ≧ 1.1 The multi-piece solid golf ball according to any one of claims 1 to 6. The multi-piece solid golf ball according to any one of claims 1 to 7, wherein the surrounding layer comprises an inner surrounding layer and an outer surrounding layer, and is formed into at least two layers. The relationship between the shore C hardness of the surface hardness of each layer is as follows: (shore C hardness of the ball surface) <(shore C hardness of the surface of the intermediate layer coated sphere)> (shore C hardness of the surface of the outer surrounding layer coated sphere) ≧ The multi-piece solid golf ball according to claim 8, which satisfies the condition of (shore C hardness on the surface of the inner surrounding layer covering sphere)> (shore C hardness on the surface of the core). Core volume (mm ³ ) x shore C hardness (Cm) at the midpoint between the core surface and core center is Core vh, inner surrounding layer volume (mm ³ ) x inner surrounding layer covering sphere surface hardness (shore C) Is IE vh, and when the volume of the outer surrounding layer (mm ³ ) × the surface hardness (shore C) of the outer surrounding layer covering sphere is OE vh, 1.0 ≤ (OE vh + IE vh) / Core vh ≤ 2. The multi-piece solid golf ball according to claim 8 or 9, which satisfies the condition of 3.

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