JP2000061001A - Multi-piece solid golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sense a soft touch in hitting a golf ball along with excellent flying performance and durability. SOLUTION: A cover 4 is formed of a cover material using a thermoplastic resin as a main material having the Shore D hardness 10-50 as in the shore D hardness of an envelope layer 2 and an intermediate layer 3 to satisfy the relationship of the Shore D hardness of the envelop layer <= the Shore D hardness of the intermediate layer <= the Shore D hardness of the cover, and an inorganic filler is added to the cover material. The hardness of a solid core is 2.5-7.0 mm in terms of the deformation value A (mm) in the care of application of a load of 100 kg. The deformation value B (mm) in the case of application of the load of 100 kg of a spherical body covered with the envelop layer on the circumference of a solid core, the deformation value C (mm) in the core of application of the load of 100 kg of the spherical body covered with the intermediate layer on the circumference of the envelop layer and the deformation value D (mm) in the case of application of the load of 100 kg of the whole of a ball satisfy respectively relations of 0.85<=B/A<=1.15, 0.85<=C/B<=1.15, and 0.7<=D/C<=1.0.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a multi-piece solid golf ball having at least a four-layer structure including a solid core, a surrounding layer, an intermediate layer and a cover, which is excellent in resilience (flying performance) and durability. The present invention relates to a multi-piece solid golf ball which is very soft and has a good feel.

[0002]

2. Description of the Related Art Conventionally, many solid golf balls such as two-piece golf balls, which have been proposed, have a trajectory which is a so-called stick ball in both driver shots and iron shots as compared with wound golf balls. In addition to having such a structure, it has an advantage that the total flight distance is increased due to a large number of runs due to the structural characteristics that the spin is hard to be applied.

On the other hand, the solid golf ball tends to be inferior in controllability as compared with the thread-wound golf ball because it is hard to spin with an iron and thus it is hard to stop on the green.

On the other hand, a golf ball has an essential element of hitting feel at the time of hitting as the flight distance increases, and without it, the commercial value is impaired. In general, a thread-wound golf ball has a structural characteristic that it is very soft and has a good feel when compared with a solid golf ball.

For this reason, in a two-piece solid golf ball consisting of a core and a cover, it is generally practiced to soften the ball structure in order to achieve a soft feel at the time of striking. Many three-piece solid golf balls which have not been obtained and which have an intermediate layer between the core and the cover have been proposed.These proposals also provide the flight distance of a two-piece solid golf ball and the hitting of a thread-wound golf ball. It was extremely difficult to obtain a golf ball having a feeling.

Recently, a multi-piece solid golf ball having a four-layer structure or more has been proposed (Japanese Patent Laid-Open Nos. 9-266959, 10-127818, 10-127819, etc.).

These proposals propose a solid golf ball having a four-layer structure including a solid core having a three-layer structure including an inner layer, an intermediate layer, and an outer layer, and a cover for covering the solid core. By providing a difference, the feel and controllability are improved.

However, when the hardness difference between the layers is large, or when the thickness and the material of the layers are not appropriate, the amount of deformation at the time of striking greatly differs between the layers, resulting in energy loss at the interface between the layers and repulsion. There is a problem in that, as a result, the flight distance is reduced, and in addition, the durability at the time of continuous impact is deteriorated.

In particular, when the materials of the adjacent layers are different and the adhesiveness thereof is low, this tendency is remarkable, and if the hardness difference between the adjacent layers is reduced, the effect of improving the feel on impact is deteriorated. There is a problem that it ends up.

The present invention has been made in view of the above circumstances, and includes a solid core, an envelope layer that covers the core, at least one intermediate layer that covers the envelope layer, and at least one layer that covers the intermediate layer. To provide a multi-piece solid golf ball having a very soft hit feeling and excellent continuous hitting durability while maintaining the excellent flight performance of the solid golf ball in a multi-piece solid golf ball having a cover of With the goal.

[0011]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above object, the present inventor has found that at least four layers including a solid core, an envelope layer, an intermediate layer and a cover are provided. In a multi-piece solid golf ball with a structure, the resilience is adjusted by adjusting the hardness and thickness of each layer, the material, and the rate of change of the amount of deformation of each spherical body before and after each layer is covered so as to satisfy a certain range. It has been found that a multi-piece solid golf ball that is excellent in golf ball feel, is extremely soft, and has a good feel at impact can be obtained.

That is, a multi-piece solid golf ball provided with a solid core, an envelope layer covering the core, at least one intermediate layer covering the envelope layer, and at least one cover covering the intermediate layer. At
Shore D hardness of the envelope layer and the intermediate layer is 10 to 50,
Forming such that the Shore D hardness of the envelope layer and the intermediate layer and the Shore D hardness of the cover satisfy the relationship of Shore D hardness of the envelope layer ≦ Shore D hardness of the intermediate layer ≦ Shore D hardness of the cover, that is, the cover. By forming the intermediate layer and the envelope layer so that they become softer toward the inside, the energy loss due to deformation at the time of impact can be suppressed as small as possible, and the resilience is improved.
The amount of deformation A (mm) under a load of 00 kg is 2.5 to 7.
0 mm, and the deformation amount B (mm) of a spherical body having a solid core coated with an envelope layer under a load of 100 kg
And a spherical body with an intermediate layer covering the surrounding layer of 100 k
The deformation amount C (mm) when a g load is applied and the deformation amount D (mm) when a 100 kg load is applied to the entire ball are 0.85 ≦ B / A ≦ 1.15 and 0.85 ≦ C /, respectively. B ≦
By satisfying the relationship of 1.15 and 0.7 ≦ D / C ≦ 1.0, the change rate of the deformation amount of each spherical body before and after each layer is covered (B / A, C / B, D / C) ) Can be set to a value close to 1, energy loss on the surface of each layer at the time of impact can be minimized, reduction in rebound can be suppressed, and the cover is mainly made of a thermoplastic resin. It is formed from a cover material as a material, and by adding an inorganic filler to this cover material, the durability upon continuous impact is dramatically improved due to its reinforcing effect, and more preferably the envelope layer and the intermediate layer are of the same kind. By forming the thermoplastic resin as a main material, the adhesion between the envelope layer and the intermediate layer is improved, and the rebound is excellent, and
Have been found to act synergistically to obtain a multi-piece solid golf ball having excellent hitting performance and durability, which is extremely soft and has a good feel. It is a thing.

Therefore, the present invention comprises (1) a solid core, at least one envelope layer that covers the core, an intermediate layer that covers the envelope layer, and at least one cover that covers the intermediate layer. In the provided multi-piece solid golf ball, the shore D hardness of the envelope layer and the intermediate layer is 10 to 50, and the Shore D hardness of the envelope layer and the intermediate layer and the Shore D hardness of the cover are the shore D of the envelope layer.
Hardness ≤ Shore D hardness of the intermediate layer ≤ Shore D hardness of the cover, and the cover is formed of a cover material containing a thermoplastic resin as a main material, and an inorganic filler is added to the cover material. In addition, the solid core has a hardness of 2.5 to 100 in a deformation amount A (mm) under a load of 100 kg.
It is 7.0 mm, and the deformation amount B (m of a spherical body having a solid core coated with an envelope layer under a load of 100 kg is
m) and a spherical body having an intermediate layer coated around the surrounding layer.
The deformation amount C (mm) under a load of 0 kg and the deformation amount D (mm) of the whole ball under a load of 100 kg are 0.85 ≦ B / A ≦ 1.15 and 0.85 ≦ C /, respectively. B
A multi-piece solid golf ball, wherein the relationship of ≦ 1.15 and 0.7 ≦ D / C ≦ 1.0 is satisfied,
(2) The multi-piece solid golf ball of (1), wherein the cover has a Shore D hardness of 48 to 68 and a thickness of 1.0 to 3.5 mm, and (3) a combined thickness of the envelope layer and the intermediate layer. A multi-piece solid golf ball according to (1) or (2), wherein
(4) The multi-piece solid golf ball according to (1), (2) or (3), wherein the envelope layer and the intermediate layer are formed of the same kind of thermoplastic resin as a main material, and (5) the cover is made of an ionomer resin as a main material. And the specific gravity thereof is 1.0 to 1.5 (1) to (4), and the inorganic filler is barium sulfate (1). A multi-piece solid golf ball according to any one of items (5) to (5) is provided.

The present invention will be described in more detail below. In the multi-piece golf ball G of the present invention, as shown in FIG. 1, a solid core 1, an envelope layer 2 covering the core 1, and an envelope layer. 2 is provided with at least one intermediate layer 3 covering the intermediate layer 2 and at least one cover 4 covering the intermediate layer 3.

The solid core 1 can be formed from a rubber composition containing a base rubber having polybutadiene rubber, polyisoprene rubber, natural rubber, and silicone rubber as a main component as a main component, and particularly, the resilience is improved. Polybutadiene rubber is preferred for this purpose. The polybutadiene rubber has a cis-structure having a cis-structure of at least 40% or more.
1,4-polybutadiene is preferred. Further, in this base rubber, natural rubber, polyisoprene rubber, styrene-butadiene rubber, etc. can be appropriately blended with the above polybutadiene, if desired, but the resilience of the golf ball is improved by increasing the polybutadiene rubber component. Therefore, the rubber component other than polybutadiene is preferably 10 parts by weight or less with respect to 100 parts by weight of polybutadiene.

In addition to the rubber component, a zinc salt of an unsaturated fatty acid such as zinc methacrylate or zinc acrylate, a magnesium salt or an ester compound such as trimethylpropane methacrylate may be added to the above rubber composition. Particularly, zinc acrylate can be preferably used because of its high resilience. The amount of these cross-linking agents blended is preferably 10 to 40 parts by weight with respect to 100 parts by weight of the base rubber.

The rubber composition usually contains a vulcanizing agent such as dicumyl peroxide, and the amount of the vulcanizing agent is 0.1 to 5 relative to 100 parts by weight of the base rubber. It can be part by weight.

The rubber composition may further contain, if necessary,
Zinc oxide, barium sulfate, or the like can be blended as an antioxidant or a filler for adjusting the specific gravity, and the blending amount of these fillers is 0 to 130 parts by weight with respect to 100 parts by weight of the base rubber.

Preferred embodiments of the rubber composition for cores of the present invention are as follows.

Cis-1,4-polybutadiene 100 parts by weight zinc oxide 0 to 50 parts by weight zinc acrylate 10 to 40 parts by weight barium sulfate 0 to 50 parts by weight peroxide 0.1 to 5.0 parts by weight antioxidant suitable amount Vulcanization conditions: preferably 5 to 20 at 150 ± 10 ° C
Vulcanize for minutes.

The core rubber composition is kneaded using a conventional kneading machine (for example, Banbury mixer, kneader, roll, etc.), and the obtained compound is injection-molded or compression-molded using a core mold. Formed by.

The solid core thus obtained is
The diameter is preferably 25.7 to 37.7 mm, more preferably 28 to 37 mm.

The amount of deformation A (mm) of the core under a load of 100 kg is 2.5 to 7.0 mm, preferably 2.8 to 6.8 mm, and more preferably 2.5 to 6.5 m.
m. If the amount of deformation is less than 2.5 mm, the feel on impact, especially when hit with large deformation such as a driver shot, becomes hard, while if it exceeds 7.0 mm, the resilience is reduced and good flight performance cannot be obtained.

The core may have a single-layer structure made of one kind of material, or a multi-layer structure made of two or more layers in which layers made of different materials are laminated.

In the present invention, the envelope layer 2 is formed by coating around the core 1. The envelope layer 2 is formed of a thermoplastic resin as a main component, and includes, for example, an ionomer resin, a polyester elastomer, a polyamide elastomer,
Examples thereof include styrene-based elastomers, polyurethane-based elastomers, olefin-based elastomers, and mixtures thereof, and thermoplastic polyester-based elastomers and polyurethane-based elastomers having a desired hardness and good resilience are particularly preferable. Specifically, "Hytrel"
Commercially available products such as (manufactured by Toray DuPont), “Pandex” (manufactured by Dainippon Ink and Chemicals, Inc.), and “Primalloy” (manufactured by Mitsubishi Chemical Co., Ltd.) can be used.

If desired, an antioxidant, a dispersant such as metal soap, etc. may be added to the envelope layer composition, and the envelope layer may be formed of a plurality of layers made of different materials. Absent.

The method of coating the surrounding layer around the core is not particularly limited, and ordinary injection molding or compression molding can be used.

The thickness of the envelope layer thus formed is preferably 0.5 to 4.0 mm, more preferably 0.7.
˜3.5 mm and its Shore D hardness is preferably 1
It is 0 to 50, more preferably 15 to 47.

Here, the deformation amount B (mm) of the spherical body formed by coating the envelope layer on the core under a load of 100 kg is 2.3 to 7.0 mm, preferably 2.5 to 6.5 mm. .

Next, at least one layer, preferably one layer or two layers, of the intermediate layer 3 is formed around the surrounding layer 2. It is preferable that the intermediate layer 3 is formed of the same kind of thermoplastic resin as the main material of the envelope layer as a main material. By forming the envelope layer and the intermediate layer from the same material in this manner, the adhesion between the two becomes high, The durability and resilience are improved. In addition, a UV absorber, an antioxidant, a dispersant such as metal soap, and the like can be added to the intermediate layer material, if necessary.

The method for coating the above-mentioned intermediate layer around the surrounding layer is not particularly limited, and ordinary injection molding or compression molding can be employed.

The thickness of the intermediate layer thus formed is preferably 0.5 to 4.0 mm, more preferably 0.7.
The total thickness of the envelope layer and the intermediate layer is preferably 2.0 to 5.0 mm, more preferably 2.0 to 4.5 mm. If the total thickness of the envelope layer and the intermediate layer is less than the above range, the effect of improving the feel on impact may be reduced, while if the total thickness is more than the above range, the resilience may be reduced.

The Shore D hardness of the intermediate layer is preferably 10 to 50, more preferably 15 to 47. When the intermediate layer is a multilayer, the Shore D hardness of each layer is within the above hardness range.

Here, the deformation amount C (mm) of the spherical body having the surrounding layer coated with the intermediate layer under a load of 100 kg is 2.3 to 6.5 mm, preferably 2.5 to 6.0 mm. . The cover 4 can be formed by using an ordinary thermoplastic resin as a main material. For example, an ionomer resin, a polyester-based elastomer, a polyamide-based elastomer,
Examples thereof include styrene-based elastomers, polyurethane-based elastomers, olefin-based elastomers, and mixtures thereof, but it is particularly preferable to use an ionomer resin as a main material. , "Surlyn" (manufactured by DuPont). In addition, a UV absorber, an antioxidant, a dispersant such as metal soap, and the like can be added to the cover material, if necessary.

The cover can be formed in at least one layer or more, preferably in one or two layers, and the method for coating the cover is not particularly limited, and ordinary injection molding or compression molding can be adopted. .

The thickness of the cover thus formed is preferably 1.0 to 3.5 mm, more preferably 1.0.
˜3.0 mm and its Shore D hardness is preferably 4
It is 8 to 68, more preferably 50 to 65.

Here, the amount of deformation D (mm) of a spherical body (that is, the entire ball) having a cover formed around the intermediate layer under a load of 100 kg is 2.3 to 6.0 mm, preferably 2.5. Is about 5.5 mm.

In the present invention, an appropriate amount of inorganic filler is added to the cover. In this case, the inorganic filler is preferably 5 to 100 parts by weight of the resin component forming the cover.
50 parts by weight, more preferably 10 to 45 parts by weight are added. If the amount of the inorganic filler added is less than 5 parts by weight, the reinforcing effect may not be obtained, while if it exceeds 50 parts by weight, the dispersibility and the resilience may be adversely affected.

The average particle size of this inorganic filler is usually 0.
The thickness is 01 to 100 μm, preferably 0.1 to 10 μm, and more preferably 0.1 to 1.0 μm. If the average particle size is too small or too large, the dispersibility at the time of filling may be deteriorated, and the effects of the present invention may not be achieved.

The specific gravity of the inorganic filler is usually preferably 4.8 or less. If the specific gravity exceeds 4.8, the cover itself becomes very heavy, which may be impractical in a golf ball whose overall weight is regulated by the Golf Rules.

Examples of such an inorganic filler include barium sulfate, titanium dioxide, calcium carbonate and the like, and one of these may be used alone or two or more of them may be used in combination, and especially barium sulfate. Is preferred.

When the inorganic filler is added to the cover as described above, the specific gravity of the cover to which the inorganic filler is added is 1.0.
˜1.5, preferably 1.05 to 1.45.

In the present invention, the Shore D hardness of the envelope layer, the intermediate layer and the cover must satisfy the relationship of Shore D hardness of the envelope layer ≦ Shore D hardness of the intermediate layer ≦ Shore D hardness of the cover. Preferably, the Shore D hardness of the envelope layer is 3 to 30 lower than the Shore D hardness of the intermediate layer, and the Shore D hardness of the intermediate layer is 5 to 3 lower than the Shore D hardness of the cover.
It is formed 5 lower.

As described above, each layer constituting the ball satisfies the above-mentioned Shore D hardness range, that is, the cover, the intermediate layer, and the surrounding layer are formed so as to become softer toward the inside. The energy loss can be suppressed as small as possible, the resilience is improved, and the flight distance is increased.

In the present invention, the rate of change (B / A, C / B, D / C) of the deformation amounts A to D of each spherical body under a load of 100 kg before and after covering each layer is set to 1. Set so that the values are close.

That is, the amount of deformation A (mm) of the solid core under a load of 100 kg, and the amount of deformation B of the spherical body with the surrounding layer coated around the solid core under a load of 100 kg.
(Mm), the amount of deformation C (mm) of the spherical body having the surrounding layer coated with the intermediate layer under a load of 100 kg, and the amount of deformation D (mm) of the entire ball under a load of 100 kg are as follows. It is necessary to meet relationships.

0.85 ≦ B / A ≦ 1.15, preferably 0.87 ≦ B / A ≦ 1.13 0.85 ≦ C / B ≦ 1.15, preferably 0.87 ≦ C
/B≦1.13 0.7 ≦ D / C ≦ 1.0, preferably 0.72 ≦ D
/C≦0.98 If the rate of change in the amount of deformation of each of these spherical bodies deviates from the above relationship, the amount of deformation at the time of impact greatly differs between layers, energy loss occurs at the interface of each layer, and the resilience decreases, It becomes impossible to increase the flight distance.

The multi-piece solid golf ball of the present invention has the above-mentioned constitution, and the materials, hardness, thickness, and
By adjusting the rate of change of the amount of deformation of each spherical body before and after covering each layer to an optimal one, it is possible to form a ball structure with less energy loss, and to improve the resilience to achieve superior flight performance. In addition to having excellent durability at the time of continuous impact, it has a very soft feel at the time of large deformation impact (driver) and small deformation impact (putter).

The golf ball of the present invention has a large number of dimples formed on the surface thereof, and the surface can be subjected to finishing treatment such as painting and stamping if necessary.
Further, the ball diameter and weight can be formed in accordance with the R & A golf rules to have a diameter of 42.67 mm or more and a weight of 45.93 g or less.

[0050]

According to the present invention, it is possible to obtain a multi-piece solid golf ball which has excellent flight performance and durability and has a very soft hit feeling.

[0051]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. The blending amounts in Table 1 are all parts by weight.

[Examples, Comparative Examples] The rubber compositions for cores having the compounding formulations shown in Table 1 were kneaded with a kneader and vulcanized in a core mold at a temperature of 155 ° C. for about 15 minutes. 1-4, the solid core of Comparative Examples 1-3 was created.

A solid having a four-layer structure of Examples 1 to 4 and Comparative Example 3 was formed by coating the surrounding layer material, the intermediate layer material and the cover material shown in Table 1 around the obtained core by injection molding. I made a golf ball. Comparative Example 1 is a two-piece golf ball including a core and a cover without an envelope layer and an intermediate layer, and Comparative Example 2 is a three-piece golf ball without an envelope layer.

Next, regarding the obtained golf ball,
Various properties were evaluated by the methods shown below. The results are shown in Table 2.
Shown in. Incidentally, the solid core hardness A, the hardness B of the spherical body with the surrounding layer coated around the core, the hardness C of the spherical body with the intermediate layer coated around the surrounding layer, and the ball hardness D were formed by coating each layer in the molding process. The measurement was performed in each state. Solid core hardness A Amount of deformation when a load of 100 kg is applied to the core (mm)
Expressed as Hardness of Spherical Body Coated with Envelope Layer Around the Core B The amount of deformation (mm) when a load of 100 kg was applied to the spherical body coated with an envelope layer around the core was expressed. Hardness C of Spherical Body Coated with Intermediate Layer Around Envelope Layer C The amount of deformation (mm) when a load of 100 kg was applied to the spherical body coated with an intermediate layer around the envelope layer. Ball hardness D Amount of deformation when a load of 100 kg is applied to the ball (m
m). Flying performance At a head speed of 45 m / sec (HS45), a swing robot manufactured by Miyame Co., Ltd. is used to carry a club with a driver ("PRO230 Titan loft 10 degrees" (manufactured by Bridgestone Sports Co., Ltd.)) and carry, total flying The distance was measured. Durability The club is driven by the Miyayamae swing robot with 10 balls obtained (see "PRO230Tit").
an loft 10 degrees "(manufactured by Bridgestone Sports Co., Ltd.) using a head speed of 45 m / sec (HS4
In 5), it was repeatedly hit 300 times, and the number of cracks was expressed. Hitting Feel Five golfers evaluated the feel when hitting actually with a driver and a putter as a club according to the following criteria. ◎: Very soft ○: Soft △: Normal ×: Hard

[0055]

[Table 1] * 1: "Hytrel" Toray-Dupont polyester-based elastomer * 2: "Primalloy" alloy material whose main component is Mitsubishi Chemical Industries polyester-based elastomer * 3: "Pebax" Atochem polyamide-based elastomer * 4: "Pandex" Dainippon Ink and Chemicals, Inc. polyurethane elastomer * 5: "Hi-Milan" Mitsui DuPont Polychemical ionomer resin * 6: "Sarin" DuPont ionomer resin

[0056]

[Table 2]

As is clear from the results shown in Table 2, Comparative Example 1
Is a general two-piece solid golf ball, which has relatively good flight distance and durability, but is hard and inferior in both the hit feeling of the driver and putter.

Comparative Example 2 is a three-piece solid golf ball similar to that disclosed in Japanese Patent Application Laid-Open No. 9-313643, in which the flight distance is slightly reduced, the durability is reduced, and the hit feeling between the driver and the putter is both slightly hard and inferior. It is a thing.

Comparative Example 3 is a four-piece solid golf ball similar to that disclosed in Japanese Unexamined Patent Publication No. 10-127819, but the hardness and thickness of each layer are not appropriate, and energy loss occurs at the interface of each layer. The flight distance and durability are both extremely poor, and the feel on impact with a small deformation (putter) is hard.

On the other hand, the balls of Examples 1 to 4 are excellent in resilience because they have a ball structure with extremely little energy loss, and the flight distance is increased. It is very soft and has a good feel.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multi-piece solid golf ball according to an embodiment of the present invention.

[Explanation of symbols]

1 solid core 2 envelope layers 3 Middle class 4 cover G golf ball

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Dr. Higuchi             Bridgestone, 20 Onohara, Chichibu City, Saitama Prefecture             Within Sports Co., Ltd. (72) Inventor Yasumasa Shimizu             Bridgestone, 20 Onohara, Chichibu City, Saitama Prefecture             Within Sports Co., Ltd.

Claims (6)

[Claims] 1. A solid core, at least one envelope layer covering the core, and an intermediate layer covering the envelope layer.
In a multi-piece solid golf ball having at least one cover for covering the intermediate layer, the shore D hardness of the envelope layer and the intermediate layer is 10 to 50, and the Shore D hardness and cover of the envelope layer and the intermediate layer are Has a Shore D hardness of the envelope layer ≦ a Shore D hardness of the intermediate layer ≦ a Shore D hardness of the cover, and the cover is formed of a cover material mainly composed of a thermoplastic resin. It is a material with an inorganic filler added,
Further, the hardness of the solid core is 2.5 to 7.0 mm in the deformation amount A (mm) when a load of 100 kg is applied, and the solid core has a spherical body coated with an envelope layer at 100 k.
g Deformation amount B (mm) when a load is applied, deformation amount C (mm) when a spherical body having an intermediate layer around the surrounding layer is applied a load of 100 kg, and deformation amount when the entire ball is applied a load of 100 kg D (mm) is 0.85 ≦ B / A ≦
1.15, 0.85 ≦ C / B ≦ 1.15, 0.7 ≦ D /
A multi-piece solid golf ball having a relationship of C ≦ 1.0. 2. The Shore D hardness of the cover is 48-6.
8. The multi-piece solid golf ball of claim 1, having a thickness of 1.0 to 3.5 mm. 3. The total thickness of the envelope layer and the intermediate layer is 2.
The multi-piece solid golf ball according to claim 1, which has a diameter of 0 to 5.0 mm. 4. The multi-piece solid golf ball according to claim 1, wherein the surrounding layer and the intermediate layer are formed of the same type of thermoplastic resin as a main material. 5. The cover mainly comprises an ionomer resin,
The multi-piece solid golf ball according to any one of claims 1 to 4, which has a specific gravity of 1.0 to 1.5. 6. The multi-piece solid golf ball according to claim 1, wherein the inorganic filler is barium sulfate.