JP2000060997A - Multi-piece solid golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give a golf ball an excellent flying performance, an extremely soft and good impact feeling, and a durability to continuous strokes. SOLUTION: The multi-piece solid golf ball G is provided with a solid core 1, at least one surrounding layer 2 covering the core 1, an intermediate layer 3 covering the surrounding layer 2 and at lest one cover 4 covering the intermediate layer 3. The solid core 1 has a hardness that exhibits deformation from 2.5 to 7.0 mm under a load of 100 kg. The intermediate layer 3 and cover 4 mainly consist of similar thermoplastic resins. The cover 4 has a Shore D hardness not less than 53, which is larger than that of the intermediate layer 3. At least either of the intermediate layer 3 and cover 4 is mixed with an inorganic filler.

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 at least a four-layer structure including a solid core, a surrounding layer, an intermediate layer and a cover, and optimizes the hardness, thickness, material, etc. of each layer. Thus, the present invention relates to a multi-piece solid golf ball which is excellent in resilience, is extremely soft, has a good feel at impact and has excellent continuous impact durability.

[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, at least one envelope layer that covers the core, an intermediate layer that covers the envelope layer, and at least one layer that covers the intermediate layer. In a multi-piece solid golf ball having a cover of, the object is to provide a multi-piece solid golf ball having a soft hit feeling and excellent continuous hit durability while maintaining the excellent flight performance of the solid golf ball. And

[0011]

Means for Solving the Problems and Embodiments of the Invention In order to achieve the above-mentioned object, the present inventor has realized a multi-piece solid golf ball having at least a four-layer structure including a solid core, an envelope layer, an intermediate layer and a cover. As a result of earnestly examining the hardness, thickness, materials, etc. of each layer in the ball,
By using the same type of thermoplastic resin, especially ionomer resin, for the cover and the intermediate layer, the adhesiveness between them is improved and the durability is improved, and the intermediate layer is made softer than the cover, and the envelope layer is made softer than the intermediate layer. In other words, by forming a ball structure that becomes softer toward the inside, it is possible to minimize energy loss due to deformation at the time of hitting, prevent reduction in resilience,
In addition to improving the durability, it has a soft hitting feel, and it is preferable to use a thermoplastic resin excellent in resilience, particularly a thermoplastic polyester elastomer or a polyurethane elastomer as a material for the envelope layer covering the periphery of the core. It has been found that it is effective and that by adding an inorganic filler to at least one layer of the cover and the intermediate layer, durability is improved due to the reinforcing effect of the inorganic filler.

As a result of further intensive studies by the present inventor based on the above findings, a solid core, at least one envelope layer covering the core, an intermediate layer covering the envelope layer, In a multi-piece solid golf ball having at least one cover that covers the intermediate layer, the solid core has a hardness of 2.5 to 7.0 mm in terms of deformation under a load of 100 kg, and the intermediate layer and the cover are The cover is formed of the same kind of thermoplastic resin as a main material, and the Shore D hardness of the cover is 53 or more. The Shore D hardness of the cover is formed higher than the Shore D hardness of the intermediate layer, and at least the cover and the intermediate layer are formed. Addition of an inorganic filler to one layer, preferably, the Shore D hardness of the envelope layer is formed to 10 to 50, and the Shore D hardness of this envelope layer is the Shore D hardness of the intermediate layer. By making the hardness lower than D hardness, the hardness, thickness, material, etc. of each layer constituting the multi-piece solid golf ball are optimized, and these layers act synergistically with each other to obtain a ball structure with extremely little energy loss. It has excellent flight performance due to improved resilience and a very soft hitting feel, and the durability of continuous impact is dramatically improved by the reinforcing effect of the inorganic filler added to any one of the cover and intermediate layer. Found that improved multi-piece solid golf ball,
The present invention has been completed.

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 hardness of the solid core is 100k.
The amount of deformation under g load is 2.5 to 7.0 mm, the intermediate layer and the cover are formed of the same kind of thermoplastic resin as a main material, and the Shore D hardness of the cover is 53 or more,
A multi-piece solid golf ball, characterized in that the Shore D hardness of the cover is formed higher than the Shore D hardness of the mid layer, and an inorganic filler is added to at least one of the cover and the mid layer, (2) cover. The total thickness of the intermediate layer and the intermediate layer is 1.5 to 5.0 mm, and the thickness of the envelope layer is 1.0 to 5.0 mm. The multi-piece solid golf ball according to (1) or (2), wherein the intermediate layer is mainly composed of an ionomer resin.
(4) The Shore D hardness of the envelope layer is 10 to 50, and the Shore D hardness of the envelope layer is lower than the Shore D hardness of the intermediate layer (1), (2) or (3). A solid golf ball, (5) the multi-piece solid golf ball according to any one of (1) to (4), wherein the layer containing an inorganic filler has a specific gravity of 1.0 to 1.5.
And (6) the multi-piece solid golf ball according to any one of (1) to (5), wherein the inorganic filler is barium sulfate.

The present invention will be described in more detail below. As shown in FIG. 1, the multi-piece golf ball G of the present invention comprises a solid core 1 and at least one envelope layer 2 covering the core 1. An intermediate layer 3 for covering the envelope layer 2 and at least one cover 4 for covering the intermediate layer 3 are provided, and each layer has proper hardness, material and thickness as described later. The inorganic filler is added to at least one of the cover and the intermediate layer.

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 22.7 to 37.7 mm, more preferably 28 to 37 mm.

The amount of deformation of the core under a load of 100 kg is 2.5 to 7.0 mm, preferably 2.8 to.
It is 6.8 mm, more preferably 3.0 to 6.5 mm. If the amount of deformation is less than 2.5 mm, the feel on impact may become 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, at least one, preferably one or two surrounding layers are formed by coating around the core. The envelope layer 2 is formed of a thermoplastic resin as a main component, and examples thereof include an ionomer resin, a polyester elastomer, a polyamide elastomer, a styrene elastomer, a polyurethane elastomer, an olefin elastomer, and a mixture thereof.
In particular, thermoplastic polyester elastomers and polyurethane elastomers having desired hardness and good resilience are suitable. Specifically, "Hytrel" (made by Toray-Dupont), "Pandex" (made by Dainippon Ink and Chemicals)
Commercially available products such as can be used.

If necessary, an antioxidant, a dispersant such as metal soap, etc. may be added to the envelope layer composition.

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 1.0 to 5.0 mm, more preferably 1.0.
~ 4.0 mm, Shore D hardness is preferably 10
50, more preferably 15 to 47.

Next, an intermediate layer 3 is formed on the periphery of the envelope layer 2 by coating. The intermediate layer 3 can be formed by using an ordinary thermoplastic resin as a main material, and examples thereof include polyester elastomers, ionomer resins, styrene elastomers, polyurethane elastomers, hydrogenated butadiene resins, and mixtures thereof. Ionomer resins are preferred. Specifically, "High Milan" (Mitsui
Commercially available products such as "DuPont Polychemical Co., Ltd." and "Surlyn" (manufactured by DuPont) can be used. 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 adopted.

The thickness of the intermediate layer thus formed is preferably 0.5 to 3.5 mm, more preferably 0.7.
~ 3.0 mm, Shore D hardness is preferably 45 ~
63, more preferably 50 to 60, and the Shore D hardness of the intermediate layer is preferably higher than the Shore D hardness of the envelope layer, and the difference in hardness is usually 5 to 5 in Shore D.
It is about 0.

The cover 4 is made of the same material as that of the intermediate layer 3, and is preferably made of an ionomer resin as a main material. By forming the cover and the intermediate layer from the same kind of material as described above, the adhesion between them is increased and the durability is improved. 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 of 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 0.5 to 3.5 mm, more preferably 0.7.
Is 3.0 mm, and the total thickness of the cover and the intermediate layer is 1.5 to 5.0 mm, preferably 2.0 to 4.5.
mm.

The Shore D hardness of the cover is 53 or more,
It is preferably 53 to 65, and the Shore D hardness of this cover needs to be formed higher than the Shore D hardness of the intermediate layer, and the hardness difference is 20 or less, preferably 1 to 15 in Shore D. . If the Shore D hardness of the cover is lower than the Shore D hardness of the intermediate layer, a ball structure in which energy loss due to deformation at the time of impact is minimized cannot be obtained, and the object of the present invention cannot be achieved.

In the present invention, an appropriate amount of an inorganic filler is added to at least one of the cover and the intermediate layer, that is, the cover only, the intermediate layer only, or both the cover and the intermediate layer.

In this case, the inorganic filler is preferably added in an amount of 5 to 50 parts by weight, more preferably 10 to 45 parts by weight, based on 100 parts by weight of the resin component forming the cover or the intermediate layer. 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 or the intermediate layer itself becomes very heavy, and the overall weight is defined by the golf rules. In some cases it may not be realistic.

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 intermediate layer and the cover as described above, the specific gravity of the intermediate layer or the cover to which the inorganic filler is added is 1.0 to 1.5, preferably 1.05.
It is 1.45.

The multi-piece solid golf ball of the present invention has the above-mentioned constitution, and the material, hardness, thickness and the like between the multiple layers should be adjusted to an optimum one, and in particular, the same thermoplastic resin for the cover and the intermediate layer. (Ionomer resin), the intermediate layer is softer than the cover, and the envelope layer is softer than the intermediate layer, that is, the ball structure becomes softer toward the inside.
To use a thermoplastic resin (thermoplastic polyester elastomer, polyurethane elastomer) that is soft and has excellent resilience as a material for the envelope layer that covers the periphery of the core, and add an inorganic filler to at least one of the cover and the intermediate layer. As a result, they act synergistically to obtain a ball structure with less energy loss than ever before, and have excellent flight performance due to improved resilience, as well as large deformation impact (driver) and small deformation impact. (Putter) has a very soft feel and has excellent durability against continuous impact.

A large number of dimples are formed on the surface of the golf ball of the present invention, and the surface can be subjected to finishing treatment such as painting and stamping if necessary.
The amount of deformation of the entire ball under a load of 100 kg is preferably 2.0 to 5.5 mm, more preferably 2.3 to 5.5 mm.
5.0 mm, the ball diameter and the weight are 42.67 mm or more and the weight is 45.9 according to the R & A golf rules.
It can be formed to 3 g or less.

[0044]

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

[0045]

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 and 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. Solid cores of 1 to 5 and Comparative Examples 1 to 3 were prepared.

The surrounding layer material, the intermediate layer material and the cover material shown in Table 1 were formed around the obtained core by injection molding to form solids having a four-layer structure of Examples 1 to 5 and Comparative Example 3. 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,
The core, ball hardness, flight performance, durability and feel on impact were measured by the following methods. The results are shown in Table 2. Hardness of core, ball The amount of deformation (mm) when a load of 100 kg was applied to the core or the ball. 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 ×: Hard

[0049]

[Table 1] * 1: "Hytrel" Toray-Dupont polyester elastomer * 2: "Pandex" Dainippon Ink & Chemicals, Inc. polyurethane elastomer * 3: "Pebax" Atochem polyamide elastomer * 4: "Hi-Milan""Mitsui DuPont Polychemical Ionomer Resin * 5:" Surrin "DuPont Ionomer Resin

[0050]

[Table 2]

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

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

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 extremely poor, and since the cover formed to be stiff is thick, the shot feel is particularly hard when hitting with a small deformation (putter).

On the other hand, in the balls of Examples 1 to 5, by optimizing the material, thickness and hardness of each layer formed in the multilayer structure, a ball structure with less energy loss can be obtained and the resilience is improved. In addition to having excellent flight performance, it has a very soft feel when hit by a driver or putter, and has excellent continuous impact durability.

[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 that covers the intermediate layer, the solid core has a hardness of 2.5 to 7.0 mm when deformed under a load of 100 kg. Is mainly formed of the same kind of thermoplastic resin, the Shore D hardness of the cover is 53 or more, and the Shore D hardness of this cover is higher than the Shore D hardness of the intermediate layer, and
A multi-piece solid golf ball, wherein an inorganic filler is added to at least one of the cover and the mid layer. 2. The combined thickness of the cover and the intermediate layer is 1.
The thickness of the envelope layer is 1.0 to 5 mm.
The multi-piece solid golf ball according to claim 1, which is 5.0 mm. 3. The multi-piece solid golf ball according to claim 1, wherein the cover and the intermediate layer are mainly made of an ionomer resin. 4. The multi-piece solid golf according to claim 1, wherein the envelope layer has a Shore D hardness of 10 to 50 and the envelope layer has a Shore D hardness lower than that of the intermediate layer. ball. 5. The specific gravity of the layer to which the inorganic filler is added is 1.0.
The multi-piece solid golf ball according to claim 1, wherein the multi-piece solid golf ball has a weight ratio of 1.5 to 1.5. 6. The multi-piece solid golf ball according to claim 1, wherein the inorganic filler is barium sulfate.