JPH0956848A - Multi-piece solid golf ball - Google Patents

Abstract

(57) Abstract: A core comprising an inner core ball and at least one surrounding layer covering the inner core ball, an inner cover for covering the core, and an outer cover for covering the inner cover. In a multi-piece solid golf ball having a cover made of, the hardness of the inner core ball is 3.5-10.0 mm, which is the softest with a deflection amount under a load of 100 kg, and the hardness of the outer cover is Shore D58. The hardness of the inner core ball is A / the hardness B of the golf ball is A / in the amount of deflection under a load of 100 kg.
A multi-piece solid golf ball, wherein B = 1.1 to 4.0. [Effect] When a player with a low head speed shots because the solid golf ball has excellent spin feeling, good flight performance, and excellent durability without sacrificing durability, and less dependency on head speed. But it can show great flight distance.

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 a structure of four or more layers. More specifically, the flight performance, the feel on impact and the control performance are improved, and the head speed dependency is small, In particular, the present invention relates to a multi-piece solid golf ball having a great flight performance even at a low head speed.

[0002]

2. Description of the Related Art
Golf balls of various structures are provided on the market, and among those generally used as golf balls for competition, a two-piece solid golf ball in which a rubber-based core is covered with a cover made of an ionomer resin or the like is used. A thread-wound golf ball in which a thread rubber is wound around a solid or liquid center and covered with a cover covers the majority.

[0003] The two-piece solid golf ball is
Although it is used by many general golfers because of its excellent flight performance and durability, it has the drawbacks that it feels very hard to hit and that it is inferior in controllability due to the speed at which the ball is released when hit. However, for this reason, professional golfers and advanced amateurs often prefer the wound golf ball to the two-piece solid golf ball. On the other hand, the thread-wound golf ball has excellent feel and controllability, but is inferior to the two-piece solid golf ball in terms of flight distance and durability.
When used by a player having a low head speed such as a senior player, the golf ball cannot be sufficiently deformed, so that the dependency of the head speed is increased, and the flight distance is not increased and a good feeling cannot be obtained. As described above, the two-piece golf ball and the thread-wound golf ball have opposing performances, and the current situation is that a player selects a golf ball to be used according to his / her skill level and preference.

For this reason, various proposals have recently been made regarding a new type of three-piece solid golf ball in order to realize a feeling similar to a wound golf ball in a solid golf ball. To obtain a feel and controllability, a soft and relatively small inner layer (outer diameter: 2
4 to 29 mm, hardness: Shore D 15 to 30 degrees) and a hard outer layer (outer diameter: 36 to 41 mm, hardness: Shore D 55 to 65)
Formed with a core coated with (degree) (Japanese Patent Publication No. 4-550)
No. 77, JP-A-64-80377), and a center core and an outermost layer of the ball in order to improve the feeling without deteriorating the good flying performance and durability characteristic of solid golf balls. There is one in which a soft intermediate layer is provided between the cover and the cover (JP-A-7-24084).

However, the above-mentioned three-piece solid golf ball having a core in which a soft and relatively small inner layer is covered with a hard outer layer does not surpass the two-piece solid golf ball in flight performance, and a hard member other than the inner layer is used. Therefore, it has not been able to satisfy the feeling of flying and feeling in a player with a low head speed. Further, since the hardness difference between the inner layer and the outer layer is large, the durability was also extremely inferior to the current two-piece solid golf ball. Further, even in a three-piece solid golf ball provided with a soft mid layer between the center core and the cover of the outermost layer of the ball, it has not been possible to obtain a good feeling yet, and a further good feeling, flight It is desired to develop a golf ball that has high performance, and particularly has sufficient flight performance even for a player with a low head speed.

The present invention has been made in view of the above circumstances, and has a soft feeling and does not spin too much without impairing the good flight performance and durability which are the features of a solid golf ball. An object of the present invention is to provide a multi-piece solid golf ball which has good flight performance, has less dependency on head speed, and has great flight performance even when shot by a player with a low head speed.

[0007]

Means for Solving the Problems and Embodiments of the Invention In order to achieve the above object, the present invention relates to the relationship between the hardness of the inner core ball and the hardness of the core in a multi-piece solid golf ball having four or more layers. As a result of earnestly examining the relationship between the hardness of the inner core ball and the ball hardness, the cover hardness, etc.,
The hardness of the inner core is 3.5-
The softest inner cover is 10.0 mm, the outer cover has a hardness of Shore D 58 degrees or more, and the inner cover has a soft inner cover, and the ratio of the hardness A of the inner core ball to the hardness B of the golf ball is 100 kg load. Deflection at time A / B =
By forming the golf ball so as to have a range of 1.1 to 4.0, the synergistic effect of the solid golf ball maintains the good flight performance and durability characteristic of the solid golf ball, and the feeling on shot is soft and good. Has a good feeling,
It reduces head speed dependency and enables great flight performance at all head speeds.In particular, even when used by low head speed players such as beginners, ladies and senior players, the flight distance increases and It was found that a good feeling can be obtained, and the present invention has been completed.

Therefore, according to the present invention, (1) a core consisting of an inner core sphere and at least one surrounding layer covering the inner core sphere, an inner cover for covering the core and the inner cover for coating the core. In a multi-piece solid golf ball having an outer cover and a cover, the hardness of the inner core ball is 3.5 to 1 in terms of the amount of deflection under a load of 100 kg.
The outer cover is formed to have a softness of 0.0 mm and the outer cover has a hardness of Shore D of 58 degrees or more, and the ratio of the hardness A of the inner core ball to the hardness B of the golf ball is 100 k.
A multi-piece solid golf ball, characterized in that the deflection amount under g load is A / B = 1.1 to 4.0,
(2) The inner core ball has a diameter of 35 mm or less, and the core has a diameter of 3
0 to 39 mm, the Shore D hardness of the inner core ball is smaller than the Shore D hardness of the envelope layer, and the amount of deflection of the core under a load of 100 kg is 2.8 to 6.5 mm. , And (3) the thickness of the outer cover is 0.5
~ 3.0mm, inner cover thickness 0.5 ~ 5.0mm
The golf ball according to (1) or (2), wherein the hardness of the inner cover is shore D57 degrees or less.

Hereinafter, the present invention will be described in more detail. The multi-piece solid golf ball 1 of the present invention
As shown in FIG. 1, a solid core 2 including an inner core ball 3 and an envelope layer 4 covering the inner core ball 3 and a cover 5 including an inner cover 6 and an outer cover 7, of which the outer cover 7 is It is characterized in that it is the hardest and the inner core ball 3 is the softest. The envelope layer 4 may be formed as a single layer (in this case, the golf ball has a four-layer structure) or a plurality of layers.

Here, the outer cover 7 is formed to have a Shore D hardness of 58 degrees or more, preferably 60 to 80 degrees, and more preferably 60 to 70 degrees. If the hardness is lower than 58 degrees,
The resilience of the ball decreases, and good flight performance cannot be obtained. On the other hand, the inner cover 6 has a Shore D hardness of 57 degrees or less,
Preferably, it is formed at 35 to 56 degrees. If the hardness is higher than 57 degrees, the flight distance cannot be obtained at a low head speed, and the feeling becomes hard. On the other hand, if the hardness is lower than 35 degrees, the resilience of the ball may decrease.

In this case, the inner cover 6 is formed softer than the outer cover 7, and if the inner cover 6 is harder than the outer cover 7, the above-described object of the present invention cannot be achieved. The inner cover 6 is recommended to have a Shore D hardness of 5 degrees or more, more preferably 5 to 30 degrees, and further preferably 5 to 20 degrees lower than the outer cover 7 for the purpose of the present invention.

The thickness of the outer cover 7 is 0.5 to 3.0.
mm, more preferably 1.0 to 2.5 mm, and the thickness of the inner cover 6 is 0.5 to 5.0 mm, more preferably 1.0 to 4.0 mm. Further, in this case, the total thickness of the cover 5 is preferably 1.0 to 8.0 mm, particularly preferably 2.0 to 6.5 mm. If the outer cover 7 is too thin, the durability of the ball deteriorates, and if it is too thick, the resilience decreases. Further, if the inner cover 6 is too thin, the feeling becomes worse, while if it is too thick, the resilience decreases. Further, if the total thickness of the cover 5 is too thin, the durability of the ball is deteriorated and the feeling is deteriorated. If it is too thick, the resilience of the ball is deteriorated and good flight performance cannot be obtained.

The material forming the inner cover 6 and the outer cover 7 is not particularly limited, and a thermoplastic resin such as an ionomer resin or a non-ionomer resin can be used to form the above-mentioned hardness. In this case, the inner covers are Hytrel 4047, 4767, 5557 (Toray
Commercially available thermoplastic elastomers such as those manufactured by DuPont) are preferably used. Also, as the outer cover, Hi-Milan 1605, 1706, AM7317, AM731
Commercially available ionomer resins such as No. 8, No. 1601, No. 1557 (manufactured by Mitsui DuPont Polychemical Co., Ltd.) and Surlyn 8120 (manufactured by DuPont) are exemplified, and these may be used alone or in combination of two or more kinds. You can

In addition to the above resin components, various additives such as pigments, dispersants, antioxidants, UV absorbers, mold release agents and the like are usually added to the cover material in a usual amount, if necessary. You can

Next, in the solid core 2, the inner core ball 3 has a hardness of 3.5 to 10.0 mm as a deflection amount when a load of 100 kg is applied, and particularly 4.0 to 9.
It is preferably 5 mm. Further, the amount of deflection when a load of 30 kg is applied is preferably 1.74 to 5.40 mm, and particularly preferably 2.02 to 5.11 mm. If the hardness of the inner core ball 3 is too small, the resilience tends to decrease, and the flight distance tends to decrease. If the hardness is too large, the feeling tends to decrease. The Shore D hardness is preferably 10 to 55 degrees, more preferably 15 to 50 degrees.

The inner core ball 3 is made of a rubber base mainly composed of polybutadiene, as in the core of a conventional two-piece solid golf ball, using an organic peroxide with a crosslinking agent such as zinc (meth) acrylate. Vulcanized ones can be used.

The envelope layer 4 covering the inner core 3 has a Shore D hardness of 45 to 70 degrees, and more preferably 48 to 69 degrees. Further, the hardness of the envelope layer 4 is preferably Shore D hardness higher than the inner core ball 3 from the viewpoint of supplementing the resilience of the very soft inner core ball 3, and the inner core ball 3
It is preferable that the hardness of the core 2 including the envelope layer 4 and the envelope layer 4 is 2.8 to 6.5 mm, particularly 3.0 to 5.5 mm in terms of the amount of deflection when a load of 100 kg is applied. Furthermore, when a 30 kg load is applied to the core 2, the deflection amount is 1.35.
˜3.43 mm, especially 1.46˜2.87 mm is preferable in order to exert the sufficient effect of the present invention.

The diameter of the inner core 3 is preferably 35 mm or less, more preferably 15 to 34 mm. If the inner core 3 is too small, it may not be possible to obtain sufficient resilience, while if it is too large, the feel on impact is adversely affected. The diameter of the core 2 including the inner sphere and the envelope layer is 30 to 39 mm, and particularly 3
It is preferably 2 to 38 mm.

The golf ball of the present invention has a hardness of 10
Deflection amount when a load of 0 kg is applied is 2.3 to 4.5 m
It is preferably m, particularly 2.5 to 4.0 mm.

In this case, the ratio of the hardness A of the inner core ball to the hardness B of the golf ball is A / B = 1.1 to 4.0, particularly 1.2 to 3. Must be 5. If A / B is smaller than 1.1, both the feel (feeling) and the resilience cannot be satisfied at the same time. When A / B is larger than 4.0, good resilience cannot be obtained and the flight distance becomes insufficient.

In the present invention, there is no limitation on the material and manufacturing method of the inner core ball of the core, and any known material and manufacturing method can be used as long as the above-mentioned golf ball characteristics can be achieved.

More specifically, the inner core sphere of the core used in the golf ball of the present invention can be obtained by adjusting the vulcanization conditions, the compounding ratio and the like by a conventional method. Usually, the base sphere is blended with a base rubber, a crosslinking agent, a co-crosslinking agent, an inert filler and the like. As the base rubber, natural rubber and / or synthetic rubber conventionally used for solid golf balls can be used. In the present invention, 1,4-polybutadiene having a cis structure of at least 40% or more is used. Particularly preferred. In this case, if necessary, natural rubber, polyisoprene rubber, styrene-butadiene rubber, or the like may be appropriately blended with the polybutadiene.

Examples of the crosslinking agent include organic peroxides such as dicumyl peroxide and di-t-butyl peroxide, but dicumyl peroxide is particularly preferable. Usually, the compounding amount of the crosslinking agent is preferably 0.5 to 1.0 part by weight based on 100 parts by weight of the base rubber.

The co-crosslinking agent is not particularly limited, and examples thereof include metal salts of unsaturated fatty acids, particularly zinc salts and magnesium salts of unsaturated fatty acids having 3 to 8 carbon atoms (eg acrylic acid, methacrylic acid, etc.). However, zinc acrylate is particularly preferred. The blending amount of this co-crosslinking agent is appropriately adjusted within 5 to 50 parts by weight with respect to 100 parts by weight of the base rubber.

Examples of the inert filler include zinc oxide, barium sulfate, silica, calcium carbonate, zinc carbonate and the like, but zinc oxide and barium sulfate are generally used, and the compounding amounts thereof are the specific gravity of the core and the cover and the ball. Although not particularly limited, the amount is usually 5 to 100 parts by weight with respect to 100 parts by weight of the base rubber. In the present invention, the optimum hardness of the inner core sphere can be obtained by appropriately adjusting the mixing ratio of zinc oxide and barium sulfate.

The composition for inner spheres obtained by blending the above components is kneaded using an ordinary kneading machine such as a Banbury mixer or a roll, and compressed or injection-molded in a die for inner spheres to obtain a molded body. Is cured by heating at a temperature sufficient for the crosslinking agent and the co-crosslinking agent to act (for example, when dicumyl peroxide is used as the crosslinking agent and zinc acrylate is used as the co-crosslinking agent, about 130 to 170 ° C.). To prepare inner spheres.

The envelope layer 4 can be formed by using a rubber base material as a main component similarly to the inner core sphere 3. It can also be formed from a thermoplastic resin such as a known ionomer resin. Specifically, commercially available ionomer resins such as Himilan 1605, 1706, 1601 and 1557 (manufactured by Mitsui-DuPont Polychemical Co., Ltd.) are used. These are exemplified, and these can be used alone or in admixture of two or more.

The envelope layer 4 can be formed on the inner core ball 3 by compression molding or injection molding using the above material to form the core 2. Furthermore, the core can be formed by the same method even when the number of surrounding layers is two or more.

The method of coating the core with the above-mentioned cover is not particularly limited, and usually, the core is wrapped with two covers which are molded in a half shell shape in advance, and the mixture is heat-pressed or the composition for the cover is injection-molded. You may wrap the core.

The golf ball thus obtained is
Dimples are formed on the cover. The geometrical arrangement is octahedron, icosahedron, etc., and the dimple pattern is any of square type, hexagon type, pentagon type, triangle type, etc. It doesn't matter.

The multi-piece solid golf ball of the present invention is suitable for medium and high head speed players, as well as low head speed, particularly head speed of about 35 m / sec, to obtain good flight distance and feel. It has very little dependence.

Although the golf ball of the present invention has the above-mentioned structure, the diameter and weight thereof can be appropriately set to a diameter of 42.67 mm or more and a weight of 45.93 g or less in accordance with the golf rules.

[0033]

EFFECTS OF THE INVENTION The multi-piece solid golf ball of the present invention is excellent in feeling without impairing proper spin performance, good flight performance, and durability which the solid golf ball originally has, and has a head speed dependency. Because of the small number, it is possible to achieve a great flight distance even when a player with a low head speed shoots.

[0034]

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] The rubber composition for inner spheres having the formulation shown in Table 1 was kneaded using a kneading roll, and
The inner core sphere was prepared by press molding at 5 ° C. for 15 minutes. The envelope layer composition having the composition shown in Table 1 was used on the inner core to obtain a core by the following method. In the case of a rubber base material, it is kneaded by a kneading roll and molded into a half-vulcanized state in a semi-vulcanized state, and then the above inner core ball is encapsulated and pressure-molded again at 155 ° C for 15 minutes to obtain a core. (Examples 2-5). On the other hand, in the case of a thermoplastic material, a core was obtained by injection molding on the above inner core ball (Example 1, Comparative Example 4).

On the obtained core, inner and outer cover materials prepared by the formulation shown in Table 1 were sequentially coated by injection molding to produce golf balls of Examples 1-5 and Comparative Examples 1-4. did. The amounts in Table 1 are all parts by weight,
The ratio is independent for the inner sphere, the surrounding layer, and the cover.

[0037]

[Table 1] * 1: Ionomer resin manufactured by Mitsui-DuPont Polychemical Co., Ltd. * 2: Polyester thermoplastic elastomer from Toray DuPont Co., Ltd. * 3: Ionomer resin manufactured by DuPont

Next, the obtained golf ball was driven with a driver (# W1) at a head speed of 45 m / sec (H
S45) and spin, carry, total flight distance, angle when shot at 35 m / sec (HS35),
The hit feeling was evaluated. Table 2 shows the results.

The hit feeling is a head speed of 45 m / se.
3 professionals from c and 3 female top amateurs with 35m / sec
The feel when hitting by name was evaluated according to the following criteria. ◎: Very soft ○: Soft △: Slightly hard ×: Hard

[0040]

[Table 2]

From the results shown in Table 2, it was confirmed that the golf ball of the present invention has a good flight feeling with an increased flight distance regardless of the high head speed (HS45) and the low head speed (HS35).

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a golf ball of the present invention.

[Explanation of symbols]

 1 Golf Ball 2 Core 3 Inner Core Sphere 4 Envelope Layer 5 Cover 6 Inner Cover 7 Outer Cover

Claims (3)

[Claims] 1. A core comprising an inner core ball and at least one surrounding layer covering the inner core ball, a cover comprising an inner cover for covering the core and an outer cover for covering the inner cover. In the multi-piece solid golf ball having the above-mentioned, the hardness of the inner core ball is 3.5-10.0 mm, which is the softest, and the outer cover has the hardness of Shore D 58 degrees or more. Formed, and the ratio of the hardness A of the inner core ball to the hardness B of the golf ball is A / in the amount of deflection under a load of 100 kg.
A multi-piece solid golf ball, wherein B = 1.1 to 4.0. 2. The diameter of the inner core sphere is 35 mm or less, the diameter of the core is 30 to 39 mm, the Shore D hardness of the inner core sphere is smaller than the Shore D hardness of the surrounding layer, and the core has a hardness of 100.
The golf ball according to claim 1, wherein the amount of deflection under a load of kg is 2.8 to 6.5 mm. 3. The thickness of the outer cover is 0.5 to 3.0 m.
The golf ball according to claim 1 or 2, wherein m, the thickness of the inner cover is 0.5 to 5.0 mm, and the hardness of the inner cover is 57 degrees or less of Shore D.