JPH09248351A - Golf ball - Google Patents

Abstract

(57) Abstract: A core, an innermost layer cover that covers the core, one or more intermediate layer covers that cover the innermost layer cover, and an outermost layer cover that covers the intermediate layer cover. A golf ball comprising a cover having a multi-layered structure of 3 or more layers, which comprises one or more intermediate layers having a cover harder than the innermost layer cover and the outermost layer cover. [Effect] A golf ball that has a good soft feeling, improves the initial velocity of the ball, increases the flight distance, and improves the spin characteristics, and particularly has excellent controllability on approach shots with sand wedges and putters. can get.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball having a multi-layered cover having three or more layers. More specifically, the golf ball has a soft feeling and the speed at which the ball jumps out when shot with a driver (ball initial velocity).
The present invention relates to a golf ball having improved spin rate, good spin on shots with a sand wedge, excellent controllability on approach shots, and excellent flight performance.

[0002]

2. Description of the Related Art Conventionally, a cover material for a thread-wound golf ball or a solid golf ball is mainly made of an ionomer resin and is molded by an injection molding method or a compression molding method. Various golf balls in which such a cover is covered with a wound core or a solid core have been proposed.

However, the above golf balls are not always fully optimized in terms of feeling, initial ball speed and spin characteristics, and if the spin characteristics are good, the ball initial speed upon shot with a driver When the initial velocity of the ball is not sufficient, the feeling may become harder, the spin characteristics may deteriorate, and the controllability on approach shots with sand wedges and putters may decrease. An optimum golf ball satisfying all the conditions has not yet been obtained, and its development has been desired.

The present invention has been made in view of the above circumstances, has a good soft feeling, improves the ball initial velocity on a shot with a driver, and improves the spin characteristics on a shot with a sand wedge or the like. It is an object of the present invention to provide a golf ball having excellent controllability on approach shots.

[0005]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the core, the innermost layer cover for covering the core, and the One or more intermediate layer covers that cover the inner layer cover;
It consists of the outermost layer cover that covers this intermediate layer cover 3
In a golf ball having a multi-layered cover having at least one layer, by forming a cover that is harder than the innermost layer cover and the outermost layer cover in the intermediate layer,
It has been found that a golf ball having a good feel, improved initial ball speed, and good spin characteristics can be obtained.

That is, the present inventors pay attention to the speed of the head speed and the resilience of the ball as the factors that influence the initial speed of the ball. Of these, the speed of the head speed is a subjective factor of the player, Repulsion of the ball affects the improvement of the initial velocity of the ball. In this case, the ball repulsion is related to the core and the cover, and if the core factor is constant, the cover factors (hardness, thickness, It was found that the initial velocity of the ball depends on the material).

Based on the above findings, the inventors of the present invention have made further studies, and as a result, in a golf ball having a core and a multi-layered cover having three or more layers covering the core,
The innermost layer cover and the outermost layer cover are formed so as to be softer than the innermost intermediate layer cover that covers immediately above the innermost layer cover, and in particular, the Shore D hardness of the outermost layer cover is less than 55 degrees, and the Shore D of the innermost layer cover is set. By setting the hardness to less than 55 degrees and forming the Shore D hardness of the innermost intermediate layer cover covering just above the innermost layer cover to 55 degrees or more,
A hard cover layer in the middle provides a sufficient initial ball velocity, which can increase the flight distance, and a soft innermost cover and outermost cover provide a good feeling and improved spin characteristics. However, the spin amount B when shot with a sand wedge at a constant head speed and the spin amount A when shot with a driver
The ratio B / A is as large as 2.5 or more, and a golf ball with excellent controllability on approach shots can be obtained, which is better than that of conventional single-layer cover or double-layer cover golf balls. The present invention has been completed by finding that a golf ball having an excellent soft feeling, an improved initial velocity of the ball, and an increased flight distance can be obtained.

Therefore, the present invention comprises a core, an innermost layer cover that covers the core, one or more intermediate layer covers that cover the innermost layer cover, and an outermost layer cover that covers the intermediate layer cover. A golf ball having a multi-layered cover having three or more layers, wherein the cover has a harder cover than the innermost cover and the outermost cover as an intermediate layer.

Hereinafter, the present invention will be described in more detail.
The golf ball of the present invention is provided with a core and a cover having a multi-layer structure of three or more layers, and various factors such as hardness, thickness, arrangement and material of the cover are adjusted to an optimum state.

Here, in the golf ball comprising the multi-layered cover of the present invention, the innermost layer cover covering the core preferably has a Shore-D hardness of less than 55 degrees, particularly 40 to 40 degrees.
51 degrees, the next innermost intermediate layer cover is preferably Shore-D
The hardness is 55 degrees or more, particularly 61 to 66 degrees, and the outermost layer cover preferably has a Shore D hardness of less than 55 degrees, particularly 34 degrees.
Form at ~ 52 degrees. In this case, it is necessary to satisfy the above three conditions, that is, it is necessary to form the innermost layer cover and the outermost layer cover softer than the innermost intermediate layer cover in order to exert the excellent effect of the present invention. If the Shore D hardness is out of the above-mentioned optimum range, the feel becomes hard, the initial velocity of the ball cannot be obtained, and the spin characteristics may be deteriorated.

In the present invention, the intermediate layer cover can be formed in one or more layers, more preferably in one or two layers. When the intermediate layer cover is two or more layers, the cover covers just above the innermost layer cover. The innermost intermediate layer cover (for example, when the cover has a four-layer structure, it means the third layer from the outermost layer side, and when it has a five-layer structure cover, it means the fourth layer from the outermost layer side). As for the hardness of the intermediate cover layer other than this, it is preferable to use a hard cover if pursuit of flying performance is desired, while it is preferable to use a soft cover if the feeling of feel is further emphasized.

The innermost cover layer has a thickness of 1.0-2.
It is preferably 0 mm, particularly 1.4 to 1.8 mm, and the material thereof is not particularly limited, but ionomer resin, polyester elastomer, polyamide elastomer, polyurethane elastomer and the like can be preferably used.
As the ionomer resin, it is possible to use a conventionally known one, for example, "HIMILAN" manufactured by Mitsui DuPont Polychemical Co., "Surlyn" manufactured by DuPont, USA, and "Iotech" manufactured by Exxon Chemical Co., Ltd. These are exemplified, and these can be used alone or in combination of two or more. Further, specific gravity and hardness can be adjusted by adding titanium dioxide, barium sulfate, magnesium stearate or the like to an ionomer resin or the like. Furthermore, if necessary, a UV absorber, an antioxidant, a dispersion aid such as metal soap, etc. may be added. The method of coating the innermost layer cover on the core is not particularly limited, and usually, the core is wrapped with two covers formed in a hemispherical shell shape in advance, and the mixture is heated and pressure-molded or the cover composition is injection-molded. Then, the method of wrapping the core and the like are preferably adopted.

The thickness of the intermediate layer cover is 1.7 to 2.5 m in the case of a golf ball having a three-layer structure cover.
m, particularly preferably 1.9 to 2.3 mm, and the material thereof can be mainly formed of the same ionomer resin as described above, and the coating method is not limited, and the injection molding method or the heat and pressure molding method can be used. Can be adopted.

When the intermediate layer cover is composed of two or more layers, it is preferable that the total thickness of these covers is considered to be the intermediate layer cover and the thickness is within the above range.
Further, in this case, it is preferable that the innermost intermediate layer cover covering immediately above the innermost layer cover has the largest thickness of the plurality of intermediate layer covers, and particularly 1.7 mm or more. Further, this innermost intermediate layer cover is preferably the hardest of the plurality of intermediate layer covers, and as described above, the Shore D hardness is 55 degrees or more, and particularly preferably 61 to 66 degrees. In this case, the hardness of the other intermediate layer is preferably the same as or slightly lower than the hardness of the outermost layer cover or the innermost layer cover. Specifically, the Shore D hardness is 30 to 54 degrees, and particularly 30 to 52 degrees. The degree is preferably. The other intermediate layers can be formed of ionomer resin, polyester elastomer, polyamide elastomer, polyurethane elastomer or the like.

The thickness of the outermost layer cover is 0.02 to 1.1.
mm, particularly preferably 0.1 to 0.5 mm,
As the material, an ionomer resin, an ethylene-vinyl acetate copolymer (EVA), polyurethane, polyethylene or the like can be used alone, or one kind or a mixture of two or more kinds thereof can be used.

The method of coating the outermost layer cover is not particularly limited, and examples thereof include an injection molding method and a heat and pressure molding method, and the heat and pressure molding method is particularly preferably used. In this case, a laminated film can be formed by the intermediate layer cover and the outermost layer cover, and the laminated film is not limited to two layers, and if desired, a laminated film having three layers, four layers or more can be used. it can. The method for forming the laminate film is not particularly limited, and a known method can be adopted, and specific examples thereof include hot melt lamination and extrusion lamination (extrusion type laminating).

A method for coating the above laminated film and
Although not particularly limited, the innermost layer cover is previously attached to the core.
Golf ball with a dimple on its surface
The laminated film on the ball.
Coat, transfer into vacuum packing machine and pack. This bow
90 ° to 150 ° C., 2
-10 minutes, 500-20,000 N / cm^Two Under the conditions
Dimples are formed on the ball surface by heat and pressure molding
You.

In the present invention, it is acceptable to form a coating film on the outermost layer cover, but the outermost layer cover has an effect as a coating film, and it is not always necessary to form a coating film. However, after the outermost layer cover is formed, it is possible to grind the burrs that have been produced and use the product as it is.
Thereby, the coating process can be omitted and a layer having a uniform thickness can be formed.

Next, the golf ball of the present invention is not particularly limited, and it can be suitably used as a wound golf ball or a solid golf ball.
The details will be described in detail.

In the case of a thread-wound golf ball, as the center ball, those normally used for thread-wound golf balls can be used, and either a liquid center or a solid center can be used, and these have a known composition. Can be

Here, when the liquid center is used, water is preferably used as the enclosed liquid. The specific gravity at this time is preferably in the range of 1.0 to 2.3, particularly 1.0 to 1.7, and in order to achieve the above specific gravity, fine powder, a surfactant or the like may be added. The above-mentioned fine powder may be any fine powder that can be made into fine powder without being dissolved in water, and specific examples thereof include fillers such as barium sulfate, zinc white, and silica. Further, examples of the surfactant include dodecylbenzene sulfonic acid, sodium dodecylbenzene sulfonate, and the like. As the rubber bag (center bag) for filling the enclosed liquid, a known bag can be used.

When a solid center is used, the composition of the polymer compound material forming the center ball is not particularly limited, but polybutadiene rubber obtained by crosslinking and curing with an unsaturated carboxylic acid or a metal salt thereof, A polybutadiene rubber obtained by crosslinking and curing with an unsaturated carboxylic acid ester, a polybutadiene rubber obtained by crosslinking and curing with an unsaturated carboxylic acid or a metal salt thereof and an unsaturated carboxylic acid ester, and the like can be preferably used. Further, in the above composition, other components such as zinc oxide, organic peroxide, and filler may be added in an appropriate ratio.

A wound core formed by winding a rubber thread around the center ball may be used. Here, the diameter of the center ball is 24-32 mm, especially 27-3.
It is preferably 1 mm, and its weight is 10 to 10.
It is preferably 26 g, particularly 16 to 23 g. Further, the type of the rubber thread and the winding method can be in accordance with a known technique, but the diameter of the thread winding core formed by winding the rubber thread around the center ball is 34 to 39 mm, particularly 3 mm.
It is preferable that the bending amount is 5 to 37 mm and the hardness is 2.8 to 6.0 mm when a load of 100 kg is applied, and particularly 3.6 to 4.8 mm.

In the case of a solid golf ball,
It is preferably used for a multi-piece solid golf ball or the like in which a solid core is covered with a cover having a multilayer structure of three or more layers. The solid core is not particularly limited, but preferably has a weight of 22 to 32 g, particularly 25 to 29 g, and a diameter of 33 to 38 mm, particularly 34 to
It is preferable that the flexure amount is 2.8 to 6.0 mm, particularly 3.5 to 4.5 mm when the load is 36 mm and the hardness is 100 kg.

There is no limitation on the material, manufacturing method, etc. of the solid core. Usually, the core is compounded with a base rubber, a crosslinking agent, a co-crosslinking agent, an inert filler and the like. In this case, natural rubber and / or synthetic rubber conventionally used for solid golf balls can be used as the base rubber, but in the present invention, 1,4-having a cis structure of at least 40% or more is used. Polybutadiene is especially 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 cross-linking agent include organic peroxides such as dicumyl peroxide and di-t-butyl peroxide, but dicumyl peroxide is particularly preferable. The co-crosslinking agent is not particularly limited, and is a metal salt of unsaturated fatty acid, particularly unsaturated fatty acid having 3 to 8 carbon atoms (eg acrylic acid, methacrylic acid, etc.).
Examples thereof include zinc salts and magnesium salts, and zinc acrylate is particularly preferred. The compounding amount of the crosslinking agent is appropriately set, and usually, with respect to 100 parts by weight of the base rubber component,
It is about 0.5 to 2 parts by weight. Further, examples of the inert filler include zinc oxide, barium sulfate, silica, calcium carbonate, zinc carbonate, and the like. Among these, zinc oxide and barium sulfate are common, and the compounding amount thereof is that of the core and the cover. It depends on the specific gravity and the weight standard of the ball and is not particularly limited, but usually 1 per 100 parts by weight of the base rubber.
0 to 30 parts by weight. In the present invention, optimum hardness of the core can be obtained by appropriately adjusting the blending ratio of the filler such as zinc oxide and barium sulfate.

The core composition obtained by blending the above-mentioned components is kneaded using an ordinary kneading machine such as a Banbury mixer or a roll, and is compressed or injection-molded with a core mold to give a molded product containing a crosslinking agent and Sufficient temperature for the co-crosslinking agent to work (for example, using dicumyl peroxide as the crosslinking agent,
When zinc acrylate is used as the co-crosslinking agent, about 13
The solid core can be prepared by heat curing at 0 to 170 ° C.

With the golf ball of the present invention having the above-mentioned structure, the head speed of 45 m /
The ratio B / A of the spin amount A when shot at sec and the spin amount B when shot at a head speed of 19 m / sec by a sand wedge is 2.5 or more, more preferably 2.55 to 2.65. Especially, the controllability at the approach shot becomes excellent. The hardness of the golf ball of the present invention is not particularly limited and is 100 k
The amount of deflection under a load of g is preferably 2.5 to 3.8 mm, and particularly preferably 2.7 to 3.1 mm.

The golf ball of the present invention has the above constitution, but the diameter, weight and initial velocity of the ball are in accordance with the Rules of Golf, the diameter is 42.67 mm or more, and the weight is 45.
It can be formed below 93g, and the initial velocity of the ball is 2
It can be 50 feet / sec (76.2 m / sec) + 2% or less.

[0029]

EFFECT OF THE INVENTION The golf ball of the present invention having the above-mentioned constitution has a good soft feeling, an improved initial velocity of the ball, an increased flight distance and an improved spin characteristic, and particularly a sand wedge. A golf ball with excellent controllability on approach shots with or putter can be obtained.

[0030]

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] Using the rubber compositions having the following compositions, solid cores were prepared by a conventional method. Rubber composition cis-1,4-polybutadiene 100 parts by weight Zinc acrylate 24 〃 Zinc oxide 19 〃 Anti-aging agent 1 〃 Dicumyl peroxide 1 〃

The core was formed by kneading each component with a kneading roll and press-molding at 155 ° C. for 15 minutes. The cover is formed based on the cover composition shown in Table 1,
The innermost layer cover and the intermediate layer cover were formed by injection molding, and the outermost layer cover was formed by pressing the film-shaped covers in Examples 1 to 4 and Comparative Example 2 in a mold. The diameter of each golf ball obtained was 42.7 mm.

Next, each solid golf ball was evaluated for flight performance, spin characteristics and feel by the following methods. Table 2 shows the results. Flying performance and spin characteristics Using a swing robot manufactured by Miyamae, a driver (W
Head speed 45m / sec (# 1) (HS4 in the table
5) and a sand wedge (SW) at a head speed of 19 m / sec (abbreviated as HS19 in the table),
Initial velocity (m / sec) and spin amount (rp)
m) was measured. A Science Eye (manufactured by Bridgestone Sports Co., Ltd.) was used to measure the spin rate. (1) Club with W # 1 head: J's-METAL loft angle 9.5 °, lie angle 57 ° made by Bridgestone Sports Co., Ltd. SUS630 stainless lost wax manufacturing shaft: Harmotech Pro HM-70 LK (tone) hardness X (2) W # 1 striking method Set the club, and set the ball 10 cm forward from the position where the shaft vertically descends to strike (Fig. 1) (3) Club head using SW: Bridgestone Sports Co., Ltd. J's-IRON
Classic Edition Loft angle 57 °, lie angle 62 ° S25C mild steel forging Shaft: Harmotech Pro HM-70 MK (medium tone) hardness X (4) SW striking method From the position where the club is set down vertically, Set the ball 30 cm behind and hit the ball (Fig. 2). 3 pros with a hitting head speed of 45 m / sec (A in Table 2,
The feel at the time of actual hitting with B and C) was evaluated according to the following criteria. ◎: Very soft ○: Soft △: Slightly hard

[0034]

[Table 1]

[0035]

[Table 2]

From the results shown in Tables 1 and 2, Comparative Example 1 is a two-piece solid golf ball having a one-layer cover. Since the cover is hard, a sufficient spin amount cannot be obtained, and the feel at impact becomes slightly hard. Further, both Comparative Example 2 and Comparative Example 3 are three-piece solid golf balls each having a cover having two layers. In Comparative Example 2, the outermost layer cover is soft and the innermost layer cover is hard, and Comparative Example 3 is the outermost layer. The cover is hard and the innermost layer cover is formed softly. Especially, in Comparative Example 3, the outermost layer cover is hard and thus the spin characteristics are inferior.

On the other hand, the golf balls of the present invention (Examples 1 to 4) are each composed of a cover having a multilayer structure of three or more layers, and the outermost cover and the innermost cover are formed so as to be softer than the innermost intermediate cover. By doing so, it was confirmed that the initial speed was improved, the spin characteristics were improved, the spin amount was increased especially in shots with a sand wedge, and the controllability on approach shots was excellent.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a method of shooting with a driver in an example and a comparative example.

FIG. 2 is an explanatory diagram of a method of shot with a sand wedge in Examples and Comparative Examples.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Michio Inoue Bridgestone Sports Co., Ltd., 20, Onohara, Chichibu City, Saitama Prefecture (72) Inventor Atsuki Kasashima, 20, Bridgestone Sports Co., Ltd.

Claims (4)

[Claims] 1. Three or more layers consisting of a core, an innermost layer cover that covers the core, one or more intermediate layer covers that cover the innermost layer cover, and an outermost layer cover that covers the intermediate layer cover. 2. A golf ball comprising the multilayer cover as described above, wherein the intermediate layer has one or more harder covers than the innermost cover and the outermost cover. 2. The golf ball according to claim 1, wherein the innermost layer cover and the outermost layer cover are formed so as to be softer than an innermost intermediate layer cover that covers immediately above the innermost layer cover. 3. The Shore D hardness of the outermost layer cover is less than 55 degrees, the Shore D hardness of the innermost layer cover is less than 55 degrees, and the Shore D hardness of the innermost intermediate layer cover covering just above the innermost layer cover is 55 degrees. The golf ball according to claim 1 or 2, wherein the golf ball has a degree or more. 4. A head speed of 45 m depending on the driver.
4. The ratio B / A of the spin rate A when shot at 1 / sec and the spin rate B when shot at a head speed of 19 m / sec with a sand wedge is 2.5 or more. A golf ball according to the item.