JP3762505B2 - Four Piece Solid Golf Ball - Google Patents

Description

【００２６】
【表２】

【００２７】
(注1) 日本合成ゴム(株)製ハイシスポリブタジエンゴム（1,4-シス-ポリブタジエン含量：96％）
(注2) 吉富製薬(株)製ヨシノックス425
(注3) 三井デュポンポリケミカル(株)製のナトリウムイオン中和エチレン-メタクリル酸共重合体系アイオノマー樹脂、MI＝2.8、曲げ剛性率＝約310MPa
(注4) 三井デュポンポリケミカル(株)製の亜鉛イオン中和エチレン-メタクリル酸共重合体系アイオノマー樹脂、MI＝0.8、曲げ剛性率＝約260MPa
(注5) 大日本インキ化学工業(株)製のポリウレタン系熱可塑性エラストマー
【００２８】
（試験方法）
▲１▼飛距離
ツルーテンパー社製スイングロボットにドライバー(Ｗ＃１)を取付け、ゴルフボールをヘッドスピード40m/秒で打撃し、落下点までの距離(キャリー)を飛距離として測定した。
▲２▼打出角およびスピン量
ゴルフボールとクラブヘッドのインパクトの瞬間を一定間隔に設置した２台のカメラによって、一定時間ずらして撮影して、その差から算出した。
▲３▼打撃時フィーリング
プロゴルファーによりドライバーで実打して評価する。評価基準は下記の通りである。
評価基準
○ …軟らかく良い
× …硬くて悪い
【００２９】
（試験結果）
【表３】

【表４】

【００３０】
以上の結果から明らかなように、本発明のフォーピースソリッドゴルフボールは、従来技術のスリーピースソリッドゴルフボールに比べて、ソフトな打撃時フィーリングを維持したまま、打撃時のボール打出角を大きくすることにより、更に飛行性能が向上することが認められた。
【００３１】
【発明の効果】
本発明のフォーピースソリッドゴルフボールは、センターと２層の中間層とカバーとから成り、センター、中間層内層、中間層外層、カバーの硬度分布を柔、剛、柔、剛となるように特定範囲に設定することで、ソフトな打撃時フィーリングを維持したまま、飛行性能を向上させ得たものである。
【図面の簡単な説明】
【図１】 本発明のゴルフボールの断面概略図である。
【符号の説明】
１ … センター
２ … 中間層内層
３ … 中間層外層
４ … カバー層
５ … 中間層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a four-piece golf ball having excellent flight performance and feeling at impact, and more particularly to a four-piece solid golf ball having a high ball launch angle at impact.
[0002]
[Prior art]
There are mainly two types of golf balls, one is a thread wound golf ball and the other is a solid golf ball. A typical example of a solid golf ball is a two-piece solid golf ball, which has a structure composed of a solid rubber core and a cover made of a thermoplastic resin.
[0003]
Although the two-piece solid golf ball has the simple structure as described above, the flight distance and durability are large, and it is generally used for amateur golfers. However, the two-piece solid golf ball is hard and has a bad shot feeling, and also has poor controllability at the time of approach.
[0004]
Various attempts have been made to improve the disadvantages of the solid golf ball. As a representative example, it has been proposed that the core has two layers or the cover has two layers. In either method, although a certain degree of effect has been obtained to soften the shot feeling, there is still room for improvement.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the problems of the conventional golf balls as described above, and to provide a golf ball having an improved flight distance while maintaining an excellent feel at impact.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors, in a four-piece solid golf ball comprising a center, two intermediate layers formed on the center, and a cover covering the intermediate layer, Center → Middle layer inner layer → Middle layer outer layer → Cover hardness distribution is set to a specific range of soft → rigid → flexible → rigid, so that the ball strikes at the time of hitting while maintaining the soft hitting feeling It has been found that a golf ball with improved flight performance can be obtained by increasing the angle, and the present invention has been completed.
[0007]
That is, the present invention comprises a center (1), two intermediate layers (5) formed on the center (1) and comprising an inner layer (2) and an outer layer (3), and the intermediate layer (5). In a four-piece solid golf ball comprising a cover (4) for covering, the center (1) has a diameter of 15 to 30 mm and a JIS-C hardness of 65 to 78 , and the intermediate layer (2) has a thickness of 1 to 3 mm and JIS-C hardness 90 to 100, the intermediate layer (3) has a thickness of 2 to 12 mm and JIS-C hardness 60 to 80, and is formed by vulcanizing and pressing a rubber composition. The cover has a thickness of 1 to 3 mm and a Shore D hardness of 62 to 72, and relates to a four-piece solid golf ball. Furthermore, in order to more suitably implement the present invention, it is desirable that (the hardness of the inner layer of the intermediate layer) − (the hardness of the center) = 15 to 35.
[0008]
The four-piece solid golf ball of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view of a four-piece solid golf ball of the present invention. In the four-piece solid golf ball of the present invention, the intermediate layer (5) is formed on the center (1), and the cover (4) is formed on the intermediate layer (5). The intermediate layer (5) is composed of two layers, an intermediate layer inner layer (2) and an intermediate layer outer layer (3). The four-piece solid golf ball of the present invention has a center (1), a two-layered intermediate layer (5), and dimensions (diameter and thickness) and hardness of the cover set within a specific range.
[0009]
The center (1) is formed to have a diameter of 15 to 30 mm and a JIS-C hardness of 60 to 80. If the diameter is smaller than 15 mm, it is difficult to understand that the feeling as a ball is soft even if the center is soft, and if it is larger than 30 mm, the resilience performance of the ball is greatly reduced and the flight distance is reduced. On the other hand, if the JIS-C hardness of the center is less than 60, it becomes too soft and the resilience performance is lowered, and if it is more than 80, it becomes too hard and the feeling becomes hard and bad.
[0010]
This center (1) is usually obtained by subjecting a known rubber composition containing a base rubber, a crosslinking agent, a metal salt of an unsaturated carboxylic acid, a filler, an anti-aging agent, etc., to heat and pressure molding. Can be formed. As the base rubber of the rubber composition, natural rubber and / or synthetic rubber conventionally used for solid golf balls is used. Particularly, cis-1,4-bond is at least 40% or more, preferably 80% or more. A so-called high-cis polybutadiene rubber is preferable. If desired, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, EPDM, or the like may be blended.
[0011]
Crosslinking agents include organic peroxides such as dicumyl peroxide or t-butyl peroxide, with dicumyl peroxide being preferred. The blending amount is preferably 1.0 to 2.0 parts by weight with respect to 100 parts by weight of the base rubber. If it is less than 1.0 part by weight, it will be too soft and the rebound will be worse and the flight distance will be reduced. If it exceeds 2.0 parts by weight, it becomes too hard and the feeling becomes worse.
[0012]
The metal salt of unsaturated carboxylic acid acts as a co-crosslinking agent, and is particularly monovalent such as zinc or magnesium salt of α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms such as acrylic acid or methacrylic acid. Or although a bivalent metal salt is mentioned, the zinc acrylate which provides high resilience is suitable. In addition, an α, β-unsaturated carboxylic acid metal salt may be used by reacting an α, β-unsaturated carboxylic acid with a metal oxide such as zinc oxide during kneading during preparation of the rubber composition. Good. The blending amount is preferably 15 to 30 parts by weight with respect to 100 parts by weight of the base rubber. If it exceeds 30 parts by weight, it will become too hard and the feeling will be poor, and if it is less than 15 parts by weight, the rebound will be poor and the flight distance will be reduced.
[0013]
The filler is not particularly limited as long as it is usually blended in the core of the golf ball. For example, inorganic salts (specifically, zinc oxide, barium sulfate, calcium carbonate), high specific gravity metal powder (for example, tungsten powder, molybdenum powder). Etc.) and mixtures thereof. Furthermore, an anti-aging agent or a peptizer can be blended as necessary.
[0014]
In the present invention, the intermediate layer (2) is coated on the center (1), and the difference in hardness between the two is obtained by changing the composition and vulcanization conditions of the composition.
(Hardness of inner layer of intermediate layer) − (Hardness of center) = 15 to 35 The intermediate layer (2) can be formed by the same method as the cover such as injection molding or press molding.
[0015]
The intermediate layer (2) is set to have a thickness of 1 to 3 mm and a JIS-C hardness of 90 to 100, and is coated on the center (1). This is because a high launch angle of the flight performance can be obtained by making the hardness distribution between the center (1) and the intermediate layer (2) into a discontinuous ultra-outer-hard / inner-soft hardness distribution. If the thickness is less than 1 mm, the resilience performance will be degraded, and if it is greater than 3 mm, the feeling at impact will be hard. The intermediate layer (2) can be formed of an ionomer resin that is usually used as a cover material for solid golf balls. As the ionomer resin, one obtained by neutralizing a part of the carboxylic acid in the ethylene- (meth) acrylic acid copolymer with a metal ion or a mixture thereof is used. Examples of the metal ions to be neutralized include alkali metal ions such as Na ions, K ions and Li ions; divalent metal ions such as Zn ions, Ca ions and Mg ions; trivalent metal ions such as Al ions, Nd ions and the like; and mixtures thereof, Na ions, Zn ions, Li ions, etc. are often used from the viewpoint of resilience and durability. Specific examples of ionomer resins include, but are not limited to, Hi Milan 1557, 1605, 1652, 1705, 1706, 1707, 1855, 1856 (Mitsui / DuPont Polychemical), IOTEC 7010, 8000 (Exxon) ) And the like.
[0016]
The intermediate layer outer layer (3) is set to have a thickness of 2 to 12 mm and a JIS-C hardness of 60 to 80, and is coated on the intermediate layer inner layer (2). If the thickness is less than 2 mm, the feeling at impact will be hard, and if it is more than 12 mm, the resilience performance will be reduced. Although the intermediate layer (3) is not particularly limited, for example, the same as the center (1) except that the amount of the crosslinking agent is 1.0 to 3.0 parts by weight with respect to 100 parts by weight of the base rubber, A known rubber composition containing a base rubber, a crosslinking agent, a metal salt of an unsaturated carboxylic acid, a filler, and an anti-aging agent as necessary can be formed by heat and pressure molding.
[0017]
The cover (4) is set to have a thickness of 1 to 3 mm and a Shore D hardness of 62 to 72, and is formed on the intermediate layer outer layer (3). If the thickness is less than 1 mm, the resilience performance is lowered and the flight distance is reduced. If the thickness is more than 3 mm, the feeling at impact is hard. This cover can be formed of an ionomer resin that is normally used as a cover material for solid golf balls. As the ionomer resin, one obtained by neutralizing a part of the carboxylic acid in the ethylene- (meth) acrylic acid copolymer with a metal ion or a mixture thereof is used. Examples of the metal ions to be neutralized include alkali metal ions such as Na ions, K ions and Li ions; divalent metal ions such as Zn ions, Ca ions and Mg ions; trivalent metal ions such as Al ions, Nd ions and the like; and mixtures thereof, Na ions, Zn ions, Li ions, etc. are often used from the viewpoint of resilience and durability. Specific examples of ionomer resins include, but are not limited to, Hi Milan 1557, 1605, 1652, 1705, 1706, 1707, 1855, 1856 (Mitsui / DuPont Polychemical), IOTEC 7010, 8000 (Exxon) ) And the like.
[0018]
In addition, the cover composition includes a filler such as barium sulfate, an additive such as titanium dioxide for coloring, and other additives such as an ultraviolet absorber, a light stabilizer, and a fluorescent material or a brightening agent. May be contained as long as the desired characteristics of the golf ball cover are not impaired. Usually, the blending amount of the colorant is preferably 0.1 to 0.5 parts by weight.
[0019]
The cover layer of the present invention is formed by a generally known method used for forming a golf ball cover, such as injection molding or press molding. When covering the cover layer, a number of depressions called dimples are usually formed on the surface. The golf ball of the present invention is usually put on the market with a paint finish, a marking stamp, etc. in order to enhance the beauty and increase the commercial value.
[0020]
【Example】
Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
[0021]
(Examples 1-6 and Comparative Examples 1-3)
Creation of center A composition for a center having the composition shown in Table 1 (Example) and Table 2 (Comparative Example) below was kneaded, pressure-molded at 140 ° C for 25 minutes, and then 165 ° C x 20 The center having the diameter or thickness and the JIS-C hardness shown in Table 3 (Example) and Table 4 (Comparative Example) was obtained by pressure molding for a minute.
[0022]
Intermediate layer inner layer On the center obtained as described above, an intermediate layer inner layer composition having the composition shown in Table 1 (Example) and Table 2 (Comparative Example) is formed by coating by injection molding. Thus, intermediate layer inner layers having thicknesses and JIS-C hardnesses shown in Table 3 (Examples) and Table 4 (Comparative Examples) were obtained.
[0023]
Intermediate layer outer layer The intermediate layer inner layer obtained as described above was coated with an intermediate layer outer layer composition having the composition shown in Table 1 (Example) and Table 2 (Comparative Example) below. The intermediate layer outer layer having the thickness and JIS-C hardness shown in Table 3 (Example) and Table 4 (Comparative Example) was obtained by pressure molding at 155 ° C. for 20 minutes.
[0024]
Cover On the outer layer of the intermediate layer obtained as described above, a cover composition having the composition shown in Table 1 (Example) and Table 2 (Comparative Example) below was coated by injection molding. A four-piece solid golf ball having the thickness and Shore D hardness shown in Table 3 (Example) and Table 4 (Comparative Example) was formed, and paint was applied on the cover in the same manner as a normal golf ball to produce a ball. Completed. The resulting golf balls were evaluated for flight performance (launch angle, spin rate, flight distance) and feel at impact, and the results are shown in Table 3 (Examples) and Table 4 (Comparative Examples). The test method was as described below.
[0025]
(Comparative Example 4)
Golf balls were produced in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 3 except that the intermediate layer outer layer was not coated. For the obtained three-piece solid golf ball, the flight performance (launch angle, spin amount, flight distance) and feel at impact were evaluated in the same manner, and the results are shown in Table 3 (Example) and Table 4 (Comparative Example). It was. The test method was as described below.
[0025]
[Table 1]

[0026]
[Table 2]

[0027]
(Note 1) Nippon Synthetic Rubber Co., Ltd. high cis polybutadiene rubber (1,4-cis-polybutadiene content: 96%)
(Note 2) Yoshinox 425 manufactured by Yoshitomi Pharmaceutical Co., Ltd.
(Note 3) Sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui DuPont Polychemical Co., Ltd., MI = 2.8, flexural rigidity = approximately 310 MPa
(Note 4) Zion ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui DuPont Polychemical Co., Ltd., MI = 0.8, flexural rigidity = approx. 260 MPa
(Note 5) Polyurethane thermoplastic elastomer manufactured by Dainippon Ink & Chemicals, Inc. [0028]
(Test method)
(1) Flying distance A driver (W # 1) was attached to a swing robot manufactured by True Temper, a golf ball was hit at a head speed of 40 m / sec, and the distance to the falling point (carry) was measured as the flying distance.
{Circle around (2)} Launch angle and spin amount The moments of impact between the golf ball and the club head were photographed while being shifted by a certain time with two cameras set at regular intervals, and calculated from the difference.
(3) Evaluation by hitting with a driver by a feeling professional golfer when hitting. The evaluation criteria are as follows.
Evaluation criteria ○… soft and good ×… hard and bad 【0029】
(Test results)
[Table 3]

[Table 4]

[0030]
As is clear from the above results, the four-piece solid golf ball of the present invention increases the ball launch angle at the time of hitting while maintaining a soft hitting feeling as compared to the three-piece solid golf ball of the prior art. As a result, it was recognized that the flight performance was further improved.
[0031]
【The invention's effect】
The four-piece solid golf ball of the present invention comprises a center, two intermediate layers and a cover, and the hardness distribution of the center, intermediate layer inner layer, intermediate layer outer layer and cover is specified to be flexible, rigid, flexible and rigid. By setting the range, the flight performance can be improved while maintaining a soft feel at impact.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a golf ball of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Center 2 ... Middle layer inner layer 3 ... Middle layer outer layer 4 ... Cover layer 5 ... Middle layer

Claims (2)

Center (1), two intermediate layers (5) formed on the center (1) and comprising an inner layer (2) and an outer layer (3), and a cover (4) covering the intermediate layer (5) The center (1) has a diameter of 15 to 30 mm and a JIS-C hardness of 65 to 78 , and the intermediate layer (2) has a thickness of 1 to 3 mm and a JIS-C hardness. 90 to 100, the intermediate layer outer layer (3) has a thickness of 2 to 12 mm and a JIS-C hardness of 60 to 80, and is formed by vulcanizing and pressing a rubber composition, and the cover is thick. A four-piece solid golf ball having a thickness of 1 to 3 mm and a Shore D hardness of 62 to 72.   The four-piece golf ball according to claim 1, wherein the intermediate layer has a JIS-C hardness of 15 to 35 higher than that of the center.

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