JP2000051397A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball having soft and comfortable ball hit feeling and remarkably improved in durability at the time of continuous hitting. SOLUTION: A golf ball includes a core 1, an intermediate layer formed by one or two layers enveloping the core, and a cover 3 mainly composed of thermoplastic resin for covering the intermediate layer, wherein the core is mainly composed of a rubber base material, when 100 kg of load is applied, the deformation amount is 3.0 mm or more, an inorganic filler is added to at least one layer of the cover and the intermediate layer, and the specific gravity of the cover is 1.0-1.3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has 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 more layers. Related to golf balls.

[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 composed of one or more layers containing an appropriate amount of an inorganic filler around a soft core. Another object of the present invention is to provide a golf ball capable of improving a good shot feeling and durability at the time of continuous hitting.

[0008]

Means for Solving the Problems and Embodiments of the Invention The present inventor has made intensive studies to achieve the above object, and as a result, has been made up of a core and one or more layers surrounding the core. In a golf ball including an intermediate 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, a soft feel at impact and excellent continuity are obtained. It has been found that it has impact durability.

That is, in a golf ball having a core, an intermediate layer comprising one or more layers surrounding the core, and a cover mainly composed of a thermoplastic resin covering the intermediate layer, The core is mainly composed of a rubber base material.
The amount of deformation under a load of 00 kg is 3.0 mm or more, an inorganic filler is added to at least one of the cover and the intermediate layer, and the specific gravity of the cover is 1.0 to 1.0.
3, preferably at least one of the intermediate layers is
The intermediate layer is formed of a resin composition containing 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 has a specific gravity of 1.0 to 1.3 and a thickness of 0. .5
By forming the core to a thickness of about 6.0 mm, the softly formed core, the intermediate layer and the cover to which an appropriate amount of an inorganic filler has been added surprisingly act synergistically, and without impairing the appearance of the ball, The present invention has been found to provide a golf ball having a soft and comfortable shot feeling at the time of hitting, and also having excellent durability in continuous hitting.

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 one or two or more multilayered intermediate layers and covers 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 hit feeling and excellent durability in continuous hitting.

Accordingly, the present invention provides (1) a core and an intermediate layer comprising one or more layers surrounding the core;
In a golf ball having a cover mainly composed of a thermoplastic resin and covering the intermediate layer, the core has a rubber base material as a main component, and the core has a deformation amount under a load of 100 kg.
A golf ball having a thickness of 0 mm or more, an inorganic filler added to at least one of the cover and the intermediate layer, and a specific gravity of the cover of 1.0 to 1.3. At least one of the layers is composed of a resin component and 100 parts by weight of the resin component and inorganic filler 5 to 5 parts by weight.
(3) The golf ball according to (1) or (2), wherein the specific gravity of the intermediate layer is 1.0 to 1.3. (1) The thickness of the intermediate layer is 0.5 to 6.0 mm (1), (2).
Alternatively, (1) the golf ball according to (3), and (5) the cover includes a resin component and 5 to 40 parts by weight of an inorganic filler based on 100 parts by weight of the resin component.
The golf ball according to any one of (1) to (4) is provided.

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

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 above-mentioned polybutadiene, but the resilience of the golf ball is improved by increasing the polybutadiene rubber component. 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, as a crosslinking agent, 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. 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
The diameter is preferably 28 to 38 mm, more preferably 30 to 37 mm, and the specific gravity is preferably 1.05 to
1.25, more preferably 1.07 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 may be formed as a single layer around the core, or may be formed as multiple layers, preferably two or three 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. If the amount of the inorganic filler is less than 5 parts by weight, the reinforcing effect may not be produced. 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), rutin 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 intermediate layer has two or more layers, 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 multilayer structure of two or more layers, it is preferable that at least one layer has a Shore D hardness of 55 or less.

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 a thermoplastic resin, and examples thereof include polyester elastomers, ionomer resins, styrene elastomers, urethane resins, hydrogenated butadiene resins, and mixtures thereof. Particularly, an ionomer resin is preferable, and specific examples thereof include "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.

In the golf ball of the present invention, a large number of dimples are 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 surface of the ball 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, the balls of Examples 1 to 4 were formed by forming an intermediate layer and a cover to which an inorganic filler was added around a 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 Middle layer 3 Cover G Golf ball

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junji Hayashi F-term (reference) 4J002 AC01W AC03W AC06W AC08W BB23X BB23Y BC05W BC05X BC05Y BL01X BL01Y CF00X CF00Y CK02X CK02DE CP03 CP03 DE236 DG046 FD016 FD050 FD070 FD097 FD140 GC01 GF00

Claims (5)

[Claims] 1. A golf ball comprising a core, an intermediate layer surrounding the core and one or more layers, and a cover mainly composed of a thermoplastic resin covering the intermediate layer. The core is mainly composed of a rubber base material, and 100
The amount of deformation under a kg load is 3.0 mm or more, an inorganic filler is added to at least one of the cover and the intermediate layer, and the specific gravity of the cover is 1.0 to 1.3.
A golf ball, characterized in that: 2. At least one of the intermediate layers comprises a resin component and an inorganic filler 5 per 100 parts by weight of the resin component.
2. The golf ball according to claim 1, wherein the golf ball contains about 40 parts by weight. 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 according to claim 1, wherein the cover contains a resin component and 5 to 40 parts by weight of an inorganic filler based on 100 parts by weight of the resin component. ball.