JP2001017570A - Solid golf ball - Google Patents

Abstract

(57) Abstract: In a multilayer golf ball comprising a core and a four-layer cover, the first layer cover covering the core has a Shore D hardness of 55 or more, and the first layer cover covering the first layer cover has a hardness of 55 or more. The Shore D hardness of the two-layer cover is 45 or less, the difference in hardness between the third layer cover and the second layer cover covering the second layer cover is 5 or more in Shore D hardness, and the third layer cover is covered. A multi-layer solid golf ball, wherein the fourth layer cover is formed to be harder than the third layer cover. The golf ball of the present invention has good flight distance performance irrespective of high / low head speed, and can improve the flight distance even when the head speed is low, and also has a good feeling. It is good.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid golf ball having a multilayer structure in which a core has at least four layers of covers.

[0002]

2. Description of the Related Art Hitherto, as a structure of a solid golf ball, a multi-layer solid golf ball having a multi-layered core and cover has been proposed (JP-A-8-336617 and JP-A-8-336617). 336618
No., 9-56848, 9-295510, 1
Nos. 1-417 and 11-4916).

The purpose of multilayering a solid golf ball is to
On the one hand, the same feeling as a thread wound golf ball is obtained, and on the other hand, the aim is to improve the flight distance. However, in general, the flight distance is not satisfied when the feeling is emphasized, and the feeling decreases when the flight distance is satisfied. In addition, many of the conventional proposals are mainly aimed at players with a high head speed, so that they provide a sufficient flight distance even when shot at a low head speed and have a good feeling The development of golf balls is further desired.

[0004] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a multi-layer solid golf ball that provides a sufficient flight distance and has a good feeling even when shot at a low head speed as well as a high head speed.

[0005]

SUMMARY OF THE INVENTION The present invention provides the following golf ball to achieve the above object. 2. A multilayer golf ball comprising a core and a four-layer cover, wherein the first layer cover covering the core has a Shore D hardness of 5%.
5 or more, the Shore D hardness of the second layer cover covering the first layer cover is 45 or less, and the hardness difference between the third layer cover and the second layer cover covering the second layer cover is 5 Shore D hardness. In addition to the above, the fourth layer covering the third layer cover
A multilayer solid golf ball, wherein the layer cover is formed harder than the third layer cover. Claim 2 The first layer cover has a Shore D hardness of 55 to 70,
The solid golf ball according to claim 1, wherein the Shore D hardness of the layer cover is 10 to 45, and the Shore D hardness of the third layer cover is 25 to 50. Claim 3 The core has a diameter of 26 to 35 mm, the surface of the core has a Shore D hardness of 40 or more, and the thickness of the fourth layer cover is 0.5.
The solid golf ball according to claim 1, wherein the diameter is from 3.0 to 3.0 mm. Claim 4 The second layer and the third layer cover are each a polyester resin,
The solid golf ball according to any one of claims 1 to 3, wherein the solid golf ball is formed of one or more of a polyurethane resin and a polyamide-based thermoplastic elastomer. 5. The solid golf ball according to claim 1, wherein the fourth layer cover is formed of an ionomer resin.

That is, the present inventor has conducted intensive studies in view of the above-mentioned object, and as a result, by forming at least the four-layer cover described above, the intermediate cover between the second and third layer covers has been formed. It is possible to provide a difference in hardness, and this makes it possible to smooth the change in hardness, thereby improving resilience and feeling, and optimizing the amount of deformation. It has been found that the present invention can be obtained, and the present invention has been accomplished.

Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention has at least one or more cores and a four-layer cover. As shown in FIG. 1, a first-layer cover 2 is formed to cover the core 1, The layer cover 3, the third layer cover 4, and the fourth layer cover 5 may be covered and formed.

The core has a diameter of 26 mm or more, particularly 29 mm or more, and 35 mm or less, particularly 33.5 or more.
mm.

[0009] The core can be formed of a rubber composition, a thermoplastic resin, or a mixture thereof. As the rubber composition, those having a known composition can be used.
Those using polybutadiene as a substrate are preferred.
The polybutadiene has a cis structure of at least 4
Preferable is 1,4-cis polybutadiene having 0% or more. In the base rubber, a natural rubber, a polyisoprene rubber, a styrene-butadiene rubber, or the like can be appropriately blended with the polybutadiene, if desired. By increasing the rubber component, the resilience of the golf ball can be improved.

The rubber composition may contain 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 as a crosslinking agent. Zinc may be suitably used. It is preferable that the compounding amount of these crosslinking agents is 10 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the base rubber.

A vulcanizing agent is usually compounded in the rubber composition, and peroxide (organic peroxide) is suitably used as the vulcanizing agent. Examples of such a peroxide include commercially available products, such as Parkmill D and Perhexa 3M (manufactured by NOF CORPORATION).
The compounding amount can be 0.6 parts by weight or more and 2 parts by weight or less based on 100 parts by weight of the base rubber.

Further, if necessary, zinc oxide, barium sulfate and the like can be blended as an antioxidant and a filler for adjusting specific gravity.

The core has a surface having a Shore D hardness of 4
0 or more, more preferably 45 or more, still more preferably 49
It is preferably 65 or less, more preferably 63 or less.

In this case, the core can be formed in a multilayer structure of two or more layers. For example, the innermost core is formed of a rubber composition, and the outer core is formed of a thermoplastic resin such as an ionomer resin so as to cover the innermost core. The outer core may be formed in such a form that the Shore D hardness is set to the above value.

The first to fourth layer covers are preferably formed of a thermoplastic resin, respectively, but can also be formed of a rubber-based material. Examples of the thermoplastic resin include polyurethane resin (polyurethane-based thermoplastic elastomer), polyester resin (polyester-based thermoplastic elastomer), polyamide-based thermoplastic elastomer,
Examples of ionomer resins include commercially available products such as Pandex (polyurethane-based thermoplastic elastomer manufactured by Dainippon Ink Co., Ltd.), Hytrel (polyester-based thermoplastic elastomer manufactured by Toray DuPont), Surlyn (manufactured by DuPont) Ionomer resin), Himilan (ionomer resin manufactured by DuPont-Mitsui), Rilsan (polyamide resin manufactured by Toray), Pepax (polyamide-based thermoplastic elastomer manufactured by Toray) and the like can be suitably used.

Here, the first layer cover is formed to have a Shore D hardness of 55 or more, preferably 60 or more. in this case,
The upper limit is a Shore D hardness of 70 or less, more preferably 68.
It is preferable to set the following. If the Shore D hardness is too low, the effect of restraining the deformation of the core is not sufficient, and there is a disadvantage that the rebound is reduced.

The first layer cover may be made of any resin as long as it is a thermoplastic resin giving the above hardness, but it is preferable to use an ionomer resin, especially a high acid ionomer resin.

The thickness of the first layer cover is 0.5 mm or more,
More preferably 0.8 mm or more, more preferably 1.0 mm
mm or more, and preferably 4.0 mm or less, more preferably 3.0 mm or less, and still more preferably 2.5 mm or less.

Next, the second layer cover has a Shore D hardness of 4
5 or less, preferably less than 45, more preferably 40 or less. If the second layer cover is harder than the above value, there is a disadvantage that a soft feeling cannot be obtained. The lower limit of the Shore D hardness of the second layer cover is preferably 10 or more, more preferably 20 or more, and further preferably 25 or more.

The second layer cover is preferably formed of a polyester resin, a polyurethane resin, a polyamide-based thermoplastic elastomer, or a mixture thereof from the viewpoint of ensuring rebound. If necessary, an ionomer resin may be mixed.

The thickness of the second layer cover is 0.5 mm or more,
More preferably 0.8 mm or more, more preferably 1.0 mm
mm or more, and preferably 4.0 mm or less, more preferably 3.0 mm or less, and still more preferably 2.5 mm or less.

The third layer cover is formed such that the difference in hardness from the second layer cover is 5 or more, especially 7 or more, in Shore D hardness. In this case, the third layer cover is preferably formed to be harder than the second layer cover. The upper limit of the hardness difference is preferably 30 or less, particularly preferably 20 or less in Shore D hardness. The resilience is improved by the difference in hardness between the second and third layer covers.

The Shore D hardness of the third layer cover is 25
The above, more preferably 30 or more, further preferably 40 or more, and preferably 50 or less, more preferably 48 or less.

This third-layer cover is preferably formed of a polyester resin, a polyurethane resin, a polyamide-based thermoplastic elastomer, or a mixture thereof, similarly to the second-layer cover. If necessary, an ionomer resin may be mixed.

The thickness of the third layer cover is 0.5 mm or more,
More preferably 0.8 mm or more, more preferably 1.0 mm
mm or more, and preferably 4.0 mm or less, more preferably 3.0 mm or less, and still more preferably 2.5 mm or less.

The fourth-layer cover needs to be formed harder than the third-layer cover. If the fourth-layer cover is softer than the third-layer cover, the object of the present invention cannot be achieved. in this case,
The Shore D hardness of the fourth layer cover is 55 or more, more preferably 60 or more, and 70 or less, more preferably 65 or less.
The following is preferred.

The material of the fourth layer cover is not particularly limited, but is preferably formed of an ionomer resin.

The thickness of the fourth layer cover is 0.5 mm or more,
More preferably, it is 1.0 mm or more, and 3.0 mm
Or less, more preferably 2.5 mm or less.

The first to fourth layer covers are preferably formed of a thermoplastic resin as described above, but may be mixed with an inorganic filler for the purpose of adjusting the specific gravity or the like. Adding an additive is optional.

The golf ball of the present invention has a thickness of 300 to 600 in accordance with a well-known arrangement as in a normal golf ball.
Individual dimples can be formed.

The golf ball of the present invention can be formed to have a diameter and a weight of 42.65 mm or more, particularly 42.67 mm or more and 42.75 mm or less in accordance with the Rules of Golf, and a weight of 45.93 g or less. Especially 45.90g
Below, it can be formed to 45.10 g or more.

[0032]

The golf ball of the present invention has good flight distance performance irrespective of high / low head speed, and can improve the flight distance even when the head speed is low. The ring is good.

[0033]

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

[Examples and Comparative Examples]
Five-piece solid golf balls shown in Table 3 were produced by the resin formulation shown in Table 2, and their flying performance and feeling were evaluated by the following methods. Table 3 shows the results. Flying performance Using a swing robot, the golf ball was hit with a driver at a head speed of 45 m / sec and 35 m / sec, respectively, and the initial speed, carry and total flight distance were measured. Feeling Three professional golfers actually tried and evaluated. ◎: Very good ○: Excellent △: Normal ×: Poor

[0035]

[Table 1] * Vulcanization conditions Core: 155 ° C, 15 minutes Inner / middle layer: 130 ° C, 10 minutes (semi-cured) → 155
℃, 15 minutes (total vulcanization)

[0036]

[Table 2]

[0037]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 core 2 first layer cover 3 second layer cover 4 third layer cover 5 fourth layer cover

Claims (5)

[Claims] 1. A multi-layer golf ball comprising a core and a four-layer cover, wherein the first layer cover covering the core has a Shore D hardness of 55 or more, and the second layer cover covering the first layer cover has a Shore D hardness of 55 or more. A D-hardness of 45 or less, a hardness difference between the third-layer cover and the second-layer cover covering the second-layer cover is 5 or more in Shore D hardness, and a fourth-layer cover covering the third-layer cover. Is formed to be harder than the third layer cover. 2. The first layer cover has a Shore D hardness of 55 to 7
2. The solid golf ball according to claim 1, wherein the second layer cover has a Shore D hardness of 10 to 45, and the third layer cover has a Shore D hardness of 25 to 50. 3. 3. The core according to claim 1, wherein the core has a diameter of 26 to 35 mm, the surface of the core has a Shore D hardness of 40 or more, and the thickness of the fourth layer cover is 0.5 to 3.0 mm. Solid golf ball. 4. The method according to claim 1, wherein the second and third layer covers are each formed of one or more of a polyester resin, a polyurethane resin, and a polyamide-based thermoplastic elastomer. Solid golf ball. 5. The solid golf ball according to claim 1, wherein the fourth layer cover is formed of an ionomer resin.