JPH10328327A - Multi-piece solid golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the flying performance, the shooting feeling and the controllability, and especially provide an excellent linearly advancing property which is not affected by a delicate undulation on a green. SOLUTION: For this multi-piece solid golf ball equipped with a core 2 comprising an inner core ball 3 and a surrounding layer 4 of at least one layer, which covers the inner core ball 3, and a cover comprising an internal cover 6 which covers the core 2, and an external cover 7 which covers the internal cover 6, the hardness of the inner core ball 3 is 1.5-4.5 mm by a deformation amount when a load of 100 kg is loaded, and the surface hardness of the surrounding layer 4 is lower than the surface hardness of the inner core ball by a Shore D hardness, and the Shore D hardness of the internal cover 6 is 55 or higher, and the Shore D hardness of the external cover 7 is 35-53, and at the same time, the ball weight is 44.5-45.93 g, and the moment of inertia is (1.52 × (ball weight (g)) + 12.79) (g.cm<2> ) or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-piece solid golf ball having a structure of four or more layers. More specifically, the present invention improves flight performance, feel and controllability, and improves straightness on a green. An excellent multi-piece solid golf ball.

[0002]

2. Description of the Related Art
Golf balls having various structures are provided on the market. Among them, a two-piece solid in which a solid core mainly composed of a rubber base material is covered with a cover made of an ionomer resin or the like is generally used as a golf ball for competition. A thread-wound golf ball in which thread rubber is wound around a golf ball and a solid or liquid center, and this is covered with the cover.

Here, two-piece solid golf balls are used by many ordinary golfers because of their excellent flight performance and durability, but they have a very hard feel when hitting, and also have a tendency to separate when hit. Has the disadvantage of being inferior in controllability due to the speed of

[0004] In order to improve the hard feel of a solid golf ball, various types of soft two-piece solid golf balls have been proposed. As a tendency of such a soft solid golf ball, generally, a soft core is generally used, but if the core is soft, the resilience is reduced, the flying performance is reduced, and the durability is significantly reduced. Not only cannot the excellent flight performance and durability inherent in a solid golf ball be maintained, but also there is a problem that it becomes difficult to withstand actual use.

[0005] Therefore, there is a need for a solid golf ball capable of improving feeling and controllability without deteriorating the flight distance and durability. And a three-piece solid golf ball having a three-layer structure with an intermediate layer interposed therebetween.

As such a three-piece solid golf ball, for example, (1) a solid core having a relatively soft inner core sphere formed by coating an intermediate layer harder than the inner sphere, Three-piece solid golf ball (Japanese Patent Publication No. 4-55077, Japanese Patent Application Laid-Open No. 64-80377, etc.) in which the contact area ratio of the club face surface is specified, and (2) a solid core (inner core ball) as an intermediate layer. A three-piece solid golf ball in which the inner cover is covered and the outer cover is further formed on the surface thereof, wherein the diameter and specific gravity of the solid core, the thickness of the inner cover, the specific gravity and JIS-C hardness,
The thickness of the outer cover is specified.
-A three-piece solid golf ball having a relatively high C hardness (for example, JP-A-7-24084), and (3) the diameter and specific gravity of the solid core, the thickness, specific gravity and JIS of the intermediate layer (inner cover). Three-piece solid golf balls (for example, Japanese Patent Application Laid-Open No. 7-24085) in which the C hardness and the thickness of the outer cover are specified, and in particular, the JIS-C hardness of the intermediate layer is specified to be relatively high, have been proposed.

However, the proposal for the three-piece solid golf ball of (1) does not clearly define the hardness of the cover, but when a golf ball having a cover with a relatively soft hardness is formed, the resilience is insufficient. On the other hand, when a golf ball having a cover with a hard hardness is formed, the hitting feeling becomes hard due to a small deformation approach shot or the like because the intermediate layer covered with the cover is harder than the solid core.

[0008] The three-piece solid golf ball of (2) can provide a soft feel, but has poor controllability because the outer cover is hard.

Further, the three-piece solid golf ball of (3) also has a relatively soft core having a core that most affects the feel and resilience. However, the resilience is insufficient when the feel is sufficiently soft. The distance is not. Conversely, if the resilience is within a sufficient range of core hardness, the intermediate layer is also hard, so the hit feeling becomes hard, and furthermore, especially for players with low head speed, the ball is not sufficiently deformed and the flight distance is not sufficiently obtained. .

[0010] In recent years, there has been a proposal to improve the above-mentioned problem of the solid golf ball by increasing the moment of inertia. For example, Japanese Patent Publication 4-484
Japanese Patent No. 73 proposes a solid golf ball in which the moment of inertia is controlled by adding a filler to a cover material or a core material, thereby increasing the flight distance and not reducing the durability or appearance of the cover surface.

However, in this proposal, although the hardness of the core is not clearly defined, the hit feeling becomes harder when a hard core is used, and a soft feel can be obtained when a soft core is used. There is a problem that the resilience is reduced and the flight performance is poor, and the outer cover is hard and the controllability is poor.

The present invention has been made in view of the above circumstances, and by optimizing the inner core sphere, the surrounding layer, the inner cover, the outer cover, the ball weight and the moment of inertia, the flying performance, hit feeling, controllability, It is an object of the present invention to provide a multi-piece solid golf ball having excellent straightness on a green.

[0013]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that an inner core ball and at least one layer covering the inner core ball are provided. In a multi-piece solid golf ball having a cover consisting of a multiple solid core consisting of an enclosing layer, an inner cover covering the core, and an outer cover covering the inner cover, the hardness of the inner core ball is 100 k.
g The amount of deformation (deflection) under load is 1.5 to 4.5 mm, the surface hardness of the surrounding layer is lower than the surface hardness of the inner core ball in Shore D hardness, and the Shore D hardness of the inner cover. And the Shore D hardness of the outer cover is 35 to 53.
And the ball weight is 44.5 to 45.93 g,
The moment of inertia is [1.52 × (ball weight (g)) +
12.79] (g · cm ² ) or more, by forming a multi-piece solid golf ball, the weight and moment of inertia of each layer of the golf ball and the entire ball are optimized, and the impact of a driver, a long iron, etc. Occasionally, it shows high resilience, has a large moment of inertia, improves spin performance and flying performance, and has a good clicking feeling despite being soft, and when approaching shots with sand wedges and short irons It was found that the spin rate was large, the run was small, the hit feeling was good, and furthermore, when putting, the straightness was excellent without being affected by subtle undulations on the green. Moreover, in this case, the inner core ball is formed mainly of a rubber base material, the diameter is set to 20 to 37 mm, and the core diameter is set to 32.
To 41 mm, and the thickness of the inner cover is 0.5
３3 mm, the thickness of the outer cover is 0.3 to 3 mm, and the difference in Shore D hardness between the inner cover and the outer cover is 5 or more. The inventors have found that the above-mentioned excellent properties can be more remarkably exhibited by blending a specific gravity inorganic filler and forming the outer cover with a thermoplastic polyurethane elastomer, and have accomplished the present invention.

Accordingly, the present invention provides (1) a core comprising an inner core sphere and at least one or more surrounding layers covering the inner core sphere, an inner cover covering the core, and the inner cover. In a multi-piece solid golf ball having an outer cover and a cover having an outer cover, the hardness of the inner core ball is 1.5 to 4.5 in terms of deformation under a load of 100 kg.
mm, and the surface hardness of the surrounding layer is lower than the surface hardness of the inner core sphere in Shore D hardness.
Hardness is 55 or more, Shore D hardness of outer cover is 35 ~
53 and the ball weight is 44.5 to 45.93.
g, wherein the moment of inertia is [1.52 × (ball weight (g)) + 12.79] (g · cm ² ) or more,
(2) The inner core ball is mainly composed of a rubber base material and has a diameter of 2
The multi-piece solid golf ball according to (1), which has a core diameter of 0 to 37 mm and a core diameter of 32 to 41 mm.
(3) The thickness of the inner cover is 0.5 to 3 mm, the thickness of the outer cover is 0.3 to 3 mm, and the difference in Shore D hardness between the inner cover and the outer cover is 5 or more (1). Or the multi-piece solid golf ball according to (2),
(4) Any one of the outer cover, the inner cover, and the surrounding layer
The above is obtained by blending a high specific gravity inorganic filler (1) to (3).
(5) The multi-piece solid golf ball according to any one of (1) to (4), wherein the outer cover is a thermoplastic polyurethane elastomer.

Hereinafter, the present invention will be described in more detail. As shown in FIG. 1, a multi-piece solid golf ball 1 of the present invention comprises a solid core 2 comprising an inner core ball 3 and an envelope layer 4 covering the inner core ball. , Inner cover 6 and outer cover 7
As described above, the hardness of the inner core sphere, the difference in surface hardness between the inner sphere and the surrounding layer, the Shore D hardness of the inner and outer covers, The ball weight and the moment of inertia are optimized. In the present invention, the surrounding layer 4 may be formed as a single layer (in this case, the golf ball has a four-layer structure) or may be formed as a plurality of layers, and there is no particular limitation.

Here, the inner core ball 3 constituting the solid core 2 has a hardness of 1.5 to 4.5 mm in the amount of deformation (deflection) when a load of 100 kg is applied, and particularly 1.8.
It is preferable that it is 4.2 mm. Where 100k
g If the amount of deformation under load is too large, the resilience decreases,
The flight distance tends to decrease, and the click feeling disappears. If the deformation amount is too small, the feeling is too low and the feeling decreases. The preferred surface hardness of the inner core ball 3 is higher than the hardness of an envelope layer described later, and is usually 40 to 70 in Shore D hardness.
In particular, it is preferably from 42 to 65.

Although the specific gravity of the inner core ball 3 is not particularly limited, it is usually 1.0 to 1.7, particularly 1.0.
It is preferable to adjust to 5 to 1.5.

In the present invention, the above-mentioned inner core ball 3 is formed in the same manner as the core of a conventional two-piece solid golf ball,
Known materials, can be formed by a manufacturing method, for example, as a material that can be used, a rubber substrate, a crosslinking agent, a co-crosslinking agent,
Inert fillers and the like can be mentioned.

Here, as the rubber substrate, natural rubber and / or synthetic rubber can be preferably used, and in particular, 1,4-polybutadiene having a cis structure of at least 40% or more can be suitably used. In this case, natural rubber, polyisoprene rubber, styrene-butadiene rubber, or the like may be appropriately blended with the polybutadiene, if desired.

Examples of the crosslinking agent include organic peroxides such as dicumyl peroxide and di-t-butyl peroxide, with dicumyl peroxide being particularly preferred. Usually, the compounding amount of the crosslinking agent is preferably 0.5 to 2.0 parts by weight based on 100 parts by weight of the rubber substrate.

Examples of the co-crosslinking agent include metal salts of unsaturated fatty acids, in particular, zinc salts and magnesium salts of unsaturated fatty acids having 3 to 8 carbon atoms (for example, acrylic acid and methacrylic acid). Zinc acid is particularly preferred. The amount of the co-crosslinking agent is 5 to 100 parts by weight of the rubber substrate.
It can be adjusted appropriately within the range of 50 parts by weight.

Examples of the inert filler include zinc oxide, barium sulfate, silica, calcium carbonate, zinc carbonate and the like. Zinc oxide and barium sulfate are generally used, and the compounding amount is specific gravity of the solid core and the cover. Although it depends on the weight standard of the ball and the like and is not particularly limited, usually, the rubber substrate 1
It is 5 to 100 parts by weight based on 00 parts by weight. In the present invention, the optimum weight and the amount of deformation of the inner sphere under a load of 100 kg can be obtained by appropriately adjusting the mixing ratio of the crosslinking agent, co-crosslinking agent, inert filler, and the like.

The composition for the inner sphere obtained by blending the above components is kneaded using a usual kneading machine, for example, a Banbury mixer or a roll, and is compressed or injection-molded into a mold for the inner sphere, and molded. The body is heat cured at a temperature sufficient for the crosslinker and co-crosslinker to act (eg, about 130-170 ° C. when dicumyl peroxide is used as the crosslinker and zinc acrylate is used as the co-crosslinker). By doing so, an inner core sphere can be prepared.

The diameter of the inner core sphere obtained as described above is appropriately adjusted according to the thicknesses of an envelope layer, an inner cover and an outer cover which will be described later. In the present invention, the diameter is 20 to 37 mm. In particular, it is preferable that the thickness be 22 to 35 mm.

Next, the surrounding layer 4 which covers the inner sphere 3 is formed so that its surface hardness is softer than the surface hardness of the inner sphere in Shore D hardness. By covering the surrounding layer 4 with a relatively soft material, it is possible to obtain a soft and clicking feel while maintaining resilience. In this case, the surface hardness of the surrounding layer is preferably 20 to 55, particularly 25 to 50, in Shore D hardness, and is preferably 5 to 50, particularly 7 to 40, lower than the surface hardness of the inner sphere.

The envelope layer 4 can be formed with a rubber base material as a main component similarly to the inner core ball 3.
It can also be formed of a thermoplastic resin such as a polyester elastomer or an ionomer resin. In this case, specific examples of the thermoplastic polyester elastomer that can be used include commercially available products such as Hytrel 4001 and 3078 (manufactured by Du Pont-Toray Co., Ltd.). These can be exemplified, and these can be used alone or in combination of two or more.

In the present invention, when forming the envelope layer, the specific gravity can be adjusted by blending a high specific gravity inorganic filler into the material, and the specific gravity depends on the base material, the inner core sphere, the cover, etc. Depends on the specific gravity of
To 1.7, especially 1.0 to 1.5. In this case, specific examples of the high specific gravity inorganic filler that can be used include tungsten, zinc oxide, and barium sulfate.

In the present invention, when a high specific gravity inorganic filler is not blended, the specific gravity depends on the specific gravity of the base material, the inner core sphere, the cover and the like.
-1.3, particularly preferably 0.9-1.2.

In order to obtain the solid core 2 using the surrounding layer 4, first, the inner core ball 3 is set in a mold,
A method of covering the inner core ball 3 by compression molding or injection molding depending on the rubber composition or the resin material of the above material can be used. Further, when the surrounding layer 4 has two or more layers, a solid core can be formed in the same manner.

In the present invention, the inner core ball 3 and the surrounding layer 4
The solid core 2 is not particularly limited as long as it satisfies the above-described surface hardness range based on the Shore D hardness, and is not particularly limited.
mm, especially 34 to 40 mm.

The multi-piece solid golf ball of the present invention is obtained by covering the solid core 2 composed of the inner core ball 3 and the surrounding layer 4 described above with a cover 5.
Is an inner cover 6 covering the surface of the solid core 2,
The outer cover 7 covers the surface of the inner cover 6.

Here, the inner cover 6 has a Shore D hardness higher than the hardness of the outer cover 7 and a Shore D hardness of 55 or more,
Particularly, the hardness of the outer cover 7 is 55 to 70, and the hardness of the outer cover 7 is Shore D.
The hardness is 35 to 53, especially 40 to 53. The difference in hardness is desirably 5 or more, preferably 5 to 25.

By softening the outer cover in this manner, the spin performance at the time of approach shot and the feel at the time of approach shot and putting can be softened. In addition, by using a resin that is hard and has good resilience for the inner cover, it is possible to maintain good flight performance.

The thickness of the inner cover 6 is 0.5
The outer cover 7 preferably has a thickness of 0.3 to 3 mm, particularly 0.5 to 2.5 mm. If the inner cover is too thick, the feeling will deteriorate, and if it is too thin, the resilience of the ball will decrease,
Good flight performance may not be obtained. On the other hand, if the outer cover is too thin, the durability of the ball deteriorates, and if it is too thick, the resilience decreases.

Further, the material constituting the inner cover 6 and the outer cover 7 is not particularly limited, and a known cover material can be used. The above-mentioned hardness is obtained by using an ionomer resin or a non-ionomer thermoplastic resin. Can be formed. In this case, as the inner cover material, Himilan 1605, 1706, AM7317, AM73
Commercially available resins such as an ionomer resin such as No. 18 (manufactured by DuPont Mitsui Polychemicals) and a thermoplastic polyester elastomer such as Hytrel 5557 (manufactured by DuPont Toray) can be used. They can be used alone or in combination of two or more.

Further, specific examples of the outer cover material include a thermoplastic polyurethane elastomer, an ionomer resin, a polyester elastomer, and a polyamide elastomer, and one or more of these can be used. Specifically, Himilan 170
Ionomer resins such as No. 6 (manufactured by Dupont Mitsui Polychemicals) and Surlyn 8120 (manufactured by Dupont);
Commercially available thermoplastic polyurethane elastomers such as Pandex T7890 and T7298 (trade name: manufactured by Dainippon Ink and Chemicals, Inc.) can be mentioned. In the present invention, in particular, the thermoplastic resins described above are used. It is preferable to use a polyurethane elastomer as a main material.

A high specific gravity inorganic filler can be added to the inner cover 6 and the outer cover 7 in order to adjust the specific gravity. As the filler, those which can be used in the above-mentioned envelope layer are compounded. Accordingly, the specific gravity depends on the specific gravity of the resin and the core serving as a base, and can be usually 1.0 to 1.5. The specific gravity in the case where the high specific gravity inorganic filler is not added depends on the resin used, but can be 0.9 to 1.2.

The multi-piece solid golf ball of the present invention has a ball weight of 44.5 to 45.93 g and has a moment of inertia (MI) equal to or greater than the value determined by the following equation (1). .

MI (g · cm ² ) = 1.52 × (ball weight (g)) + 12.79 (1)

That is, according to the study of the present inventors, the moment of inertia has an appropriate range in correlation with the cover hardness. That is, if the cover is hard, the cover needs to be large, and if the cover is soft, the cover does not need to be large. If the cover is soft, the frictional force at impact is large and spin is easy to apply.On the other hand, if the cover is hard, the frictional force is small and spin is difficult to apply. If the moment of inertia is small, it will decay quickly, and will stall when falling. Conversely, a ball hit with a high spin rate using a soft cover, if the moment of inertia is too large, will have a small spin decay, and will tend to blow up due to excessive spin during flight, and all will have a short flight distance. It tends to decrease.

In the golf ball of the present invention, the cover 5 is composed of a hard inner cover and a soft outer cover. Since the solid core composed of the sphere and the soft surrounding layer is formed so as to cover the solid core, the definition of the moment of inertia suitable for the hard / soft structure is adapted to the range described above. Therefore, if the moment of inertia is lower than the above-described value, the spin holding force is not sufficient, and a trajectory with elongation cannot be obtained, resulting in a reduction in flight distance.

By increasing the moment of inertia in this way, the rolling performance on the green at the time of putting is improved, and an excellent straightness that is not affected by a subtle undulation on the green is obtained. Can be.

The moment of inertia is a calculated value obtained from the diameter (thickness) and specific gravity of each layer, and can be obtained by the following equation (2) by regarding the ball as a sphere. In this case, although the ball is spherical in calculation, the specific gravity of the outer cover layer is smaller than the actual outer cover resin because dimples actually exist. Here, it is called the outer cover virtual specific gravity, and the moment of inertia is calculated using this.

MI = A × ｛(ab) × m^Five+ (Bc) × n^Five+ (Cd) × p^Five + D × q^Five… ... (2) MI: Moment of inertia (gcm)^Two A: constant, π / 5880000 a: inner core specific gravity b: surrounding layer specific gravity c: inner cover specific gravity d: outer cover virtual specific gravity m: inner core spherical diameter n: core diameter p: after covering the core with the inner cover Sphere diameter q: ball diameter * The unit of diameter and thickness of each layer is mm

Accordingly, the specific gravity, diameter, and the like of the inner sphere, the surrounding layer, the inner cover, and the outer cover are appropriately selected, and the moment of inertia obtained from Equation (2) is calculated by the ball weight determined by Equation (1). The value is set to a value equal to or greater than the moment of inertia.

Although the above equation (2) is for a case where the surrounding layer is a single layer, the same equation can be used for the case where the surrounding layer is a multilayer.

As described above, the golf ball of the present invention
The respective layers of the inner core ball 3, the surrounding layer 4, the inner cover 6, and the outer cover 7, and the ball weight and the moment of inertia of the golf ball on which these layers are laminated are optimized.
When hit with a driver or long iron, it has good rebound and moderately suppressed spin amount, and it can increase the flight distance by extending trajectory with good spin holding power without blow-up When hit with a short iron or pitching wedge, the spin characteristics stop well, and a hit ball with less run and excellent controllability can be obtained, so you can aim the pin deadly and put it on the green In the case of performing, a good straightness that is hardly influenced by subtle undulations due to excellent rolling properties is obtained, a good hit feeling with a soft and moderate click feeling is obtained in any shot and putting, and a round It can exhibit excellent performance in every situation inside.

A large number of dimples can be formed on the surface of the golf ball of the present invention in the same manner as a normal golf ball. In this case, the number of dimples is not particularly limited, but is usually 300 to 550, particularly 33
It can be 0 to 500 pieces. Further, the dimples may be two or more types having different diameters and depths. The arrangement of the dimples is not particularly limited.
Known arrangements such as a dihedral arrangement and a regular icosahedral arrangement can be employed. Furthermore, the pattern drawn on the ball surface by the arrangement of dimples is also square, hexagon,
Various patterns such as a pentagon shape and a triangle shape can be used.

In the golf ball of the present invention, the properties of the ball can be appropriately set in accordance with the rules of golf as long as it does not deviate from the above range.

[0050]

According to the multi-piece solid golf ball of the present invention, since the inner core ball, the surrounding layer, the inner cover, and the outer cover, and the ball weight and the moment of inertia are optimized, the flying performance, hit feeling, It has excellent controllability and, in particular, has excellent straightness without being affected by subtle undulations on the green, and can exhibit excellent performance in any scene during a round.

[0051]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples and Comparative Examples] Solid golf balls having the properties shown in Table 2 by a known method using a rubber composition and a thermoplastic resin having the composition shown in Table 1 (all units are parts by weight). Was obtained respectively. In this case, the surface of the outer cover of the obtained golf ball has a dimple of 2
420 pieces were formed in an octahedral arrangement.

The golf balls of Comparative Examples 1 to 4 were formed based on the following publications and the like and have the following features.

Comparative Example 1: A three-piece solid golf ball formed according to JP-A-7-24085,
The core (only the inner core sphere) has a relatively high Shore D hardness (Shore D hardness of 50) and has no surrounding layer.

Comparative Example 2: A three-piece solid golf ball formed according to JP-A-7-24085,
The Shore D hardness of the core (only the inner core sphere) is relatively soft (Shore D hardness 42), and there is no surrounding layer.

Comparative Example 3: A three-piece solid golf ball formed according to Japanese Patent Publication No. 4-48473,
The specific gravity of the inner cover is relatively large, and the moment of inertia is large.

Comparative Example 4: A general two-piece solid golf ball having a relatively hard core (Shore D hardness: 5)
4) An outer cover softer than the Shore D hardness of the core is formed.

For each of the obtained golf balls, the moment of inertia, flying performance, spin performance, hit feeling, and rolling property were evaluated by the following methods. The results are also shown in Table 2.

[0059]Moment of inertia The diameter and thickness of each component were obtained by measuring five arbitrary points.
Values were averaged. On the way to make the ball for weight
With the inner core ball, core, inner cover,
Each weight was measured. Also, from this measurement
The weight and volume were calculated, and the specific gravity was calculated. In this case, outside
For the cover, the above-mentioned virtual specific gravity was used. These values
Is applied to the following equation (2) to calculate the moment of inertia.
Was. MI = A × ｛(ab) × m^Five+ (Bc) × n^Five+ (Cd) × p^Five + D × q^Five… ... (2) MI: Moment of inertia (gcm)^Two A: constant, π / 5880000 a: inner core specific gravity b: surrounding layer specific gravity c: inner cover specific gravity d: outer cover virtual specific gravity m: inner core spherical diameter n: core diameter p: after covering the core with the inner cover Sphere diameter q: ball diameter * The unit of diameter and thickness of each layer is mm

Flight performance Using a swing robot manufactured by True Temper, a driver (PRO 230) was used.
Head speed 50m using Titan, loft 10 degrees (Bridgestone Sports Co., Ltd.) (# W1)
/ Sec (HS50) and 35 m / sec (HS35) were measured for spin, carry, and total flight distance, respectively.

Spin Performance Using a swing robot similar to that described above, using a sand wedge (J's Classical Edition (manufactured by Bridgestone Sports Corp.) (#SW)) at a head speed of 25 m / sec (HS25). The spin amount and run (difference between the total and the carry) at the time of performing were measured.

The driving feel (# W1) and the sand wedge (#S) by five professional golfers with a hitting head speed of about 50 m / sec.
W) and the feel when hitting a putter (#PT) were evaluated according to the following criteria. (# W1) ：: Soft click feeling △: Soft but no click feeling and unreliable hit feeling ×: Hard (#SW) ○: Soft △: Normal ×: Hard (#PT) ：: Soft △: Normal × :hard

Rolling property The rolling condition of the ball at the time of putting in the hit feeling evaluation was evaluated according to the following criteria. ：: Straight ahead and rolling elongation. ×: lacks straightness and lacks elongation.

[0064]

[Table 1] Himilan: Ionomer resin manufactured by DuPont-Mitsui Polychemicals Surlyn: Ionomer resin manufactured by DuPont Hytrel: Polyester thermoplastic elastomer manufactured by Toray DuPont Pandex: Thermoplastic polyurethane elastomer manufactured by Dainippon Ink and Chemicals

[0065]

[Table 2] * Amount of ball deformation under a load of 100 kg (mm) ** Moment of inertia at a ball weight of 45.3 g determined from the above equation (1): 81.65 g · cm ²

According to the multi-piece solid golf ball of the present invention, the inner sphere, the surrounding layer, the inner cover, and the outer cover, and the ball weight and the moment of inertia are optimized, so that the flight distance is increased, The golf ball has excellent spin performance, soft and click feeling, and has few runs, so it has good controllability and is excellent in straightness not affected by subtle undulation on the green. Was done. On the other hand, Comparative Example 1
The golf ball of the golf ball of Comparative Example 2 has a hard hit feeling when hit with a driver and a small moment of inertia, thus lacking spin sustainability, inferior flight performance, and poor rolling at the time of putting. , But the feel is soft,
The so-called "coreless" softness has no clicking feeling, and the core and cover are soft, so it has poor resilience and a small moment of inertia, so it lacks spin persistence, poor flight performance, and when hitting putters Rolling condition is inferior.
Further, the golf ball of Comparative Example 3 has a large specific gravity of the inner cover and a large moment of inertia, so that the spin has sustainability and can provide a long flight distance, but the core is hard, so the hit feeling is hard, and the cover is hard. The golf ball of Comparative Example 4 is hard and lacks controllability. Further, the golf ball of Comparative Example 4 has a hard core, so that the hit feeling is hard, and the cover is soft, so the spin amount is large, the flight distance is poor, and the moment of inertia is low. Since it was small, it lacked spin sustainability, and was inferior in flight performance, controllability, and rolling condition during putting.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a multi-piece solid golf ball of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-piece solid golf ball 2 Solid core 3 Inner core ball 4 Surrounding layer 5 Cover 6 Inner cover 7 Outer cover

Claims (5)

[Claims] 1. A core comprising a core sphere and at least one surrounding layer covering the core sphere, a cover comprising an inner cover covering the core and an outer cover covering the inner cover. In the multi-piece solid golf ball, the hardness of the inner sphere is 1.5 to 4.5 mm in a deformation amount under a load of 100 kg, and the surface hardness of the surrounding layer is Shore D hardness and the surface of the inner sphere is The inner cover has a Shore D hardness of 55 or more, the outer cover has a Shore D hardness of 35 to 53, a ball weight of 44.5 to 45.93 g, and a moment of inertia of [1.52 × (ball weight (g)) + 12.79] (g
A multi-piece solid golf ball having a size of at least ² cm ² ). 2. The inner core ball is mainly composed of a rubber base material,
The diameter is 20 to 37 mm, and the core diameter is 32 to
The multi-piece solid golf ball according to claim 1, which is 41 mm. 3. The thickness of the inner cover is 0.5 to 3 mm,
3. The multi-piece solid golf ball according to claim 1, wherein the outer cover has a thickness of 0.3 to 3 mm, and a difference in Shore D hardness between the inner cover and the outer cover is 5 or more. 4. 4. The multi-piece solid golf ball according to claim 1, wherein at least one of the outer cover, the inner cover, and the surrounding layer contains a high specific gravity inorganic filler. 5. The multi-piece solid golf ball according to claim 1, wherein the outer cover is a thermoplastic polyurethane elastomer.