JP2002355344A - Golf ball - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a golf ball having a soft and comfortable shot feeling and a remarkably improved durability upon continuous hitting. SOLUTION: In a golf ball provided with a core, one intermediate layer surrounding the core, and a cover mainly composed of an ionomer resin for covering the intermediate layer, the core is mainly composed of a rubber base material. The diameter of the core is 28 to 38 mm
And the amount of deformation of the core under a load of 100 kg is 3.
0 mm or more, the intermediate layer and the cover each contain a resin component and 5 to 40 parts by weight of an inorganic filler with respect to 100 parts by weight of the resin component, and the specific gravity of the cover is 1 0.0 to 1.3, the middle layer has a Shore D hardness of 45 to 70, the cover has a Shore D hardness of 45 to 70, and the middle layer hardness is lower than the cover hardness. Golf ball.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a golf ball having a good shot feeling and a significantly improved durability by adding an appropriate amount of an inorganic filler to a cover and an intermediate layer comprising one or two layers. About the ball.

[0002]

2. Description of the Related Art Conventionally, many techniques for adding an inorganic filler to a cover material have been proposed (JP-B 5-73427, JP-A-6-27712, JP-A-57-25867 and JP-A-60-210272).

[0003] Above all, Japanese Patent Application Laid-Open No. Hei 6-27712 discloses that by adding an inorganic filler such as titanium white and barium sulfate to a cover material, the weight distribution in the ball is shifted from the center of the core to the cover side. By increasing the moment of inertia of the ball itself, suppressing the decay of spin during flight,
As a result, it becomes difficult to apply the initial spin at the time of impact, and the flight distance can be increased.

However, all of these proposals basically aim at increasing the moment of inertia of the ball by increasing the specific gravity of the cover and improving the flight distance performance. If too much is added, the resilience and cracking durability of the ball are impaired.

[0005] On the other hand, a golf ball is required to have a comfortable feel at the time of hitting, and without it, the commercial value is impaired.

For this reason, various proposals have been made to improve the feel at impact, but in the category of the prior art, if a soft feel at impact is obtained, on the other hand, durability in continuous hitting is reduced. It has been extremely difficult to provide a good feel at impact and an improvement in durability with continuous hits at the same time.

The present invention has been made in view of the above circumstances, and an object thereof is to form an intermediate layer and a cover consisting of one or two layers in which an appropriate amount of an inorganic filler is added around a soft core. It is an object of the present invention to provide a golf ball capable of improving a good shot feeling and durability during continuous hitting.

[0008]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has found that a core and an intermediate layer comprising one or two layers surrounding the core are provided. In a golf ball having a layer and a cover mainly composed of a thermoplastic resin covering the intermediate layer, by adding an appropriate amount of an inorganic filler to the cover and the intermediate layer,
It has been found that the golf ball has a soft feel at impact and excellent continuous hitting durability.

That is, in a golf ball having a core, an intermediate layer consisting of one or two layers surrounding the core, and a cover mainly composed of an ionomer resin, which covers the intermediate layer, the core comprises a core. The rubber base material is a main component, the core has a diameter of 28 to 38 mm, the deformation of the core under a load of 100 kg is 3.0 mm or more, and at least one layer of the intermediate layer and the cover are made of resin. Component and 100 parts by weight of this resin component, inorganic filler 5
The cover is formed from a resin composition containing 40 parts by weight, and the specific gravity of the cover is set to 1.0 to 1.3, preferably the specific gravity of the intermediate layer is set to 1.0 to 1.3. The thickness is formed to be 0.5 to 6.0 mm. Further, when the intermediate layer is one layer, the Shore D hardness of the intermediate layer is 45 to 7
0, when the number of intermediate layers is two, the Shore D hardness of one layer is 45 to 70, and the Shore D hardness of at least one layer is 55 or less; and the Shore D hardness of the cover is 45 to 70. By setting the specific gravity of the inorganic filler to 70, especially 50 to 68, and even 6.5 or less, the softly formed core, the intermediate layer and the cover to which an appropriate amount of the inorganic filler is added, surprisingly Acting synergistically, it was found that a golf ball having a soft and comfortable hitting feel at the time of hitting and having excellent durability at the time of continuous hitting can be obtained without impairing the appearance of the ball, and completed the present invention. It was done.

It is an object of the present invention to increase the moment of inertia of a ball by adding an inorganic filler to a cover material and increasing the specific gravity of the cover, as in the prior art, to improve flight performance. Rather, by combining a soft core and a single or double-layered intermediate layer and cover in which an inorganic filler is uniformly dispersed in an appropriate amount, these act synergistically, It is an object of the present invention to obtain a golf ball having an unprecedented good shot feeling and excellent durability in continuous hitting.

Accordingly, the present invention provides a golf ball comprising: (1) a core, a single intermediate layer surrounding the core, and a cover mainly composed of an ionomer resin, which covers the intermediate layer. A rubber base material as a main component, the diameter of the core is 28 to 38 mm, the deformation of the core under a load of 100 kg is not less than 3.0 mm, and the intermediate layer and the cover are , This resin component 1
It contains 5 to 40 parts by weight of an inorganic filler with respect to 00 parts by weight, and the specific gravity of the cover is 1.0 to 1.
3, the middle layer has a Shore D hardness of 45 to 70,
A golf ball, wherein the cover has a Shore D hardness of 45 to 70 and an intermediate layer hardness lower than the cover hardness, (2) an intermediate layer comprising a core and two layers surrounding the core And a cover comprising an ionomer resin as a main material covering the intermediate layer.
The core has a rubber base as a main component, and the core has a diameter of 28.
And the deformation of the core under a load of 100 kg is 3.0 mm or more, and at least one of the intermediate layers and the cover are filled with a resin component and 100 parts by weight of the resin component with an inorganic filler. 5 to 40 parts by weight of the agent, and the specific gravity of the cover is 1.0 to
1.3 and the inner middle layer has a Shore D hardness of 45-7.
0, the outer middle layer has a Shore D hardness of 55 or less, the cover has a Shore D hardness of 45 to 70, and the outer middle layer hardness is lower than the inner middle layer and the cover hardness. A golf ball is provided.

Hereinafter, the present invention will be described in more detail. As shown in FIG.
A solid core 1, an intermediate layer 2 surrounding the solid core 1 (single layer) or a multilayered two-layer structure (FIG. 1 shows a case where the intermediate layer is a single layer); And a cover 3 having a multi-layer structure. As described later, an appropriate amount of an inorganic filler is added to at least one of the intermediate layers and the cover.

The solid core 1 can be formed from a rubber composition mainly composed of a base rubber mainly composed of polybutadiene rubber, polyisoprene rubber, natural rubber, and silicone rubber. For this purpose, polybutadiene rubber is preferred. As the polybutadiene rubber, a cis-structure having at least 40% or more of a cis structure can be used.
1,4-polybutadiene is preferred. In the base rubber, natural rubber, polyisoprene rubber, styrene-butadiene rubber, and the like can be appropriately blended with the polybutadiene, if desired. Therefore, the rubber component other than polybutadiene is preferably not more than 10 parts by weight based on 100 parts by weight of polybutadiene.

The rubber composition may contain, in addition to the rubber component, a crosslinking agent such as zinc salts of unsaturated fatty acids such as zinc methacrylate and zinc acrylate, magnesium salts, and ester compounds such as trimethylpropane methacrylate. Particularly, zinc acrylate can be suitably used because of its high resilience. The amount of these crosslinking agents is preferably 15 to 40 parts by weight based on 100 parts by weight of the base rubber.

The rubber composition usually contains a vulcanizing agent such as dicumyl peroxide and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane. The amount of this vulcanizing agent is 10
It can be 0.1 to 5 parts by weight with respect to 0 parts by weight.

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

Preferred embodiments of the rubber composition for a core according to the present invention are as follows.

Cis-1,4-polybutadiene 100 parts by weight Zinc oxide 5-40 parts by weight Zinc acrylate 15-40 parts by weight Barium sulfate 0-40 parts by weight Peroxide 0.1-5.0 parts by weight 1,1- Bis (t-butylperoxy) 3,3,5-trimethylcyclohexane 0.1 to 5.0 parts by weight Antioxidant appropriate amount Vulcanization condition: preferably 5 to 20 at 150 ± 10 ° C
Vulcanize for a minute.

The above-mentioned rubber composition for a core is kneaded using a usual kneader (for example, a Banbury mixer, a kneader or a roll), and the obtained compound is subjected to injection molding or compression molding using a core mold. Is formed.

The solid core thus obtained is
Its diameter is 28-38mm, preferably 30-37mm
Having a specific gravity of 1.05 to 1.25, preferably 1.0 to 1.25.
7 to 1.23.

The amount of deformation of the core under a load of 100 kg must be 3.0 mm or more, preferably 3.0 to 8 mm, more preferably 3.3 to 7.0 mm.
It is. If the amount of deformation of the core is less than 3.0 mm, the core becomes too hard, the shot feeling at the time of hitting becomes hard, and the object of the present invention cannot be achieved. On the other hand, if it exceeds 8 mm, the core becomes too soft, and the resilience may be significantly reduced. The core may have a single-layer structure made of one kind of material, or may have a multi-layer structure made up of two or more layers made of different kinds of materials.

The intermediate layer 2 can be formed as a single layer around the core, or can be formed as two layers around the core.

The intermediate layer mainly contains a thermoplastic resin,
For example, polyester elastomer, ionomer resin,
Examples thereof include styrene-based elastomers, urethane-based resins, hydrogenated butadiene resins, and mixtures thereof. Specific examples include “Himilan” (manufactured by DuPont Mitsui Polychemicals), “Surlyn” (manufactured by DuPont), and “ Commercial products such as "Hytrel" (manufactured by Dupont Toray) and "Pandex" (manufactured by Dainippon Ink and Chemicals, Inc.) can be used.

Here, when the intermediate layer is formed as a single layer around the core, it is particularly preferable to use an ionomer resin as a main material, and two intermediate layers (around the first intermediate layer) around the core. When the second intermediate layer is coated).
It is preferable that a relatively high hardness ionomer resin is used as a main component for the first intermediate layer, and a polyester-based elastomer, a polyurethane-based elastomer, or the like, which is softer than the first intermediate layer, is used for the second intermediate layer.

In the present invention, when the intermediate layer has one layer, an inorganic filler is added to the intermediate layer. When the intermediate layer has a two-layer structure, an inorganic filler is added to only one or both layers.

In this case, 5 to 4 parts by weight of the inorganic filler are added to 100 parts by weight of the resin component forming the intermediate layer to which the inorganic filler is added.
0 parts by weight, preferably 10 to 38 parts by weight, more preferably 13 to 36 parts by weight. The amount of inorganic filler added is 5
If the amount is less than the weight part, the reinforcing effect may not be generated. On the other hand, if it exceeds 40 parts by weight, the dispersibility and resilience may be adversely affected.

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

The specific gravity of the inorganic filler is usually 6.5 or less, preferably 2.0 to 6.0.

Examples of such an inorganic filler include barium sulfate (specific gravity of about 4.47), rutile type titanium white (specific gravity of about 4.17), and calcium carbonate (specific gravity of about 2.6).
These can be used alone or in combination of two or more.

Incidentally, an antioxidant, a dispersant such as metal soap and the like can be added to the intermediate layer composition, if necessary.

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

The specific gravity of the intermediate layer thus formed is 1.0 to 1.3 as a whole, preferably 1.02 to 1.2.
8, more preferably 1.05 to 1.26.

The total thickness of the intermediate layer is preferably 0.5 to 6.0 mm, more preferably 1.0 to 5.0 m.
m, and when the number of the intermediate layers is two, the thickness of the layer to which the inorganic filler is added is preferably 0.7 to 4.0 mm, more preferably 0.8 to 3.5 mm.

When the number of the intermediate layers is one, the Shore D hardness is 45 to 70, preferably 55 to 70. When the intermediate layer has a two-layered multilayer structure, the outer intermediate layer has a Shore D hardness of 55 or less, and the inner intermediate layer has a Shore D hardness of 45 to 70, preferably 55 to 70.

The cover is coated around the spherical body comprising the intermediate layer containing the soft core and the inorganic filler thus obtained.

The cover 3 is formed of a cover material mainly composed of an ionomer resin. As the ionomer resin, specifically, “HIMILAN” (manufactured by DuPont Mitsui Polychemicals) and “Surlyn” (manufactured by DuPont) ).

In the present invention, an appropriate amount of an inorganic filler is added to the cover. In this case, the amount of the inorganic filler to be added is 5 to 40 with respect to 100 parts by weight of the resin component forming the cover.
Parts by weight, preferably 8 to 37 parts by weight.

As such an inorganic filler, the same one as the above-mentioned intermediate layer can be used. Note that a UV absorber, an antioxidant, a dispersant such as metal soap, or the like can be added to the cover material as needed.

The method for coating the cover on the intermediate layer is not particularly limited, and ordinary injection molding or compression molding can be employed.

The cover thus formed has a specific gravity of 1.0 to 1.3, preferably 1.03 to 1.28.
It is.

The thickness of the cover is preferably 0.5 to
The cover has a Shore D hardness of 45 to 70, preferably 5 to 2.5 mm, more preferably 0.8 to 2.3 mm.
0 to 68. The cover may be formed in a plurality of layers selected from different materials.

The golf ball of the present invention has a soft and comfortable feel at impact and durability in repeated hits dramatically improved by having the above structure.

Incidentally, 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 a finishing treatment such as painting and stamping if necessary. In addition, the hardness of the entire ball is preferably 2.6 to 5.0 m, which is a deformation amount generated when a load of 100 kg is applied.
m, more preferably 3.0 to 4.8 mm, and the ball diameter and weight are in accordance with the R & A Golf Rules, and the diameter is 42.
It can be formed in a size of 67 mm or more and a weight of 45.93 g or less.

[0044]

According to the present invention, a golf ball having a soft and comfortable shot feeling and a durability upon continuous hitting dramatically improved by a combination of a soft core, an intermediate layer to which an appropriate amount of an inorganic filler is added, and a cover. Is obtained.

[0045]

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. The amounts in Tables 1 and 2 are all parts by weight.

[Examples and Comparative Examples] The rubber compositions for cores having the composition shown in Table 1 were kneaded in a kneader and vulcanized in a core mold at a temperature of 155 ° C for about 15 minutes. A solid core of a comparative example was prepared.

Solid golf balls of Examples 1 to 4 and Comparative Examples 1 and 2 were formed by coating an intermediate layer material and a cover material shown in Table 2 around the obtained core by injection molding in combination with the combinations shown in Table 3. It was created. Comparative Example 2 is a two-piece golf ball having a core and a cover without an intermediate layer.

Next, regarding the obtained golf ball,
Core hardness, continuous impact durability, shot feeling, and appearance were measured by the following methods. The results are also shown in Table 3. Core Hardness Deformation (mm) when a 100 kg load was applied to the core. Use a continuous impact durability swing robot to drive the ball (J's
World Stage With a loft angle of 11 degrees (Bridgestone Sports Co., Ltd.), a head speed of 4
After repeatedly hitting at a condition of 5 m / sec, the state of occurrence of cracks on the ball surface was relatively compared by the number of hits. ：: No problem at all ○: Cracks generated Δ: Relatively early destruction ×: Premature destruction hitting feeling Feel when actually hit by four professional golfers was evaluated according to the following criteria. ：: soft and comfortable ○: good △: slightly hard ×: hard appearance The state of the ball surface after molding was visually observed and evaluated according to the following criteria. ：: extremely good ○: good △: slightly bad ×: bad

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

[Table 3]

From the results shown in Table 3, in Comparative Example 1, the first intermediate layer and the cover contained only 2 parts by weight of the inorganic filler, the second intermediate layer did not contain the inorganic filler, and the specific gravity of the cover was 0.1%. 9
Since it is as small as 8, the durability in continuous hitting is inferior.

Comparative Example 2 is a conventional two-piece ball having a core and a cover, which is inferior in durability and ball appearance in continuous hitting, and extremely poor in shot feeling.

On the other hand, in the balls of Examples 1 to 4, the intermediate layer and the cover were formed by adding an inorganic filler around the soft core, so that durability in continuous impact, shot feeling, and ball appearance were obtained. Both are excellent.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a golf ball according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid core 2 Intermediate layer 3 Cover G Golf ball

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Junji Hayashi Inside Bridgestone Sports Co., Ltd. 20 Onohara, Chichibu City, Saitama Prefecture

Claims (5)

[Claims] 1. A golf ball comprising a core, an intermediate layer surrounding the core, and a cover mainly composed of an ionomer resin for covering the intermediate layer, wherein the core comprises a rubber base material as a main component. And the diameter of the core is 28 to 38 mm
And the amount of deformation of the core under a load of 100 kg is 3.
0 mm or more, the intermediate layer and the cover each contain a resin component and 5 to 40 parts by weight of an inorganic filler with respect to 100 parts by weight of the resin component, and the specific gravity of the cover is 1 0.0 to 1.3, the middle layer has a Shore D hardness of 45 to 70, the cover has a Shore D hardness of 45 to 70, and the middle layer hardness is lower than the cover hardness. Golf ball. 2. A golf ball comprising: a core; an intermediate layer comprising two layers surrounding the core; and a cover mainly composed of an ionomer resin, which covers the intermediate layer.
The core has a rubber base as a main component, and the core has a diameter of 28.
And the deformation of the core under a load of 100 kg is 3.0 mm or more, and at least one of the intermediate layers and the cover are filled with a resin component and 100 parts by weight of the resin component with an inorganic filler. 5 to 40 parts by weight of the agent, and the specific gravity of the cover is 1.0 to
1.3 and the inner middle layer has a Shore D hardness of 45-7.
0, the outer middle layer has a Shore D hardness of 55 or less, the cover has a Shore D hardness of 45 to 70, and the outer middle layer has a lower hardness than the inner middle layer and the cover hardness. Characteristic golf ball. 3. The golf ball according to claim 1, wherein the specific gravity of the intermediate layer is 1.0 to 1.3. 4. The thickness of the intermediate layer is 0.5 to 6.0 mm.
The golf ball according to claim 1, 2 or 3, wherein 5. The golf ball according to claim 1, wherein the specific gravity of the inorganic filler is 6.5 or less.