JP4431845B2 - Rubber composition for golf ball and golf ball - Google Patents

Description

【００４２】
表１の結果より、本発明のゴルフボール用ゴム組成物にて形成されたソリッドコアは、いずれも加圧成形が採用できる加硫時間で成形でき、適度な硬度と、優れた初速性能を有するものであった。
【００４３】
これに対して、比較例１，２は、いずれも初速性能が実施例よりも劣るものであった。
特に、実施例と比較例１とを比較すると、ｔ−ノニルメルカプタンの配合の有無以外は同一組成であり、実施例はコアの硬度（変形量）は若干比較例１より低いが、いずれも比較例１よりも初速性能に優れていることが確認された。
【００４４】
また、比較例３，４のコア材中には、芳香族硫黄化合物が少量配合されているが、初速が遅く、硬度もやわらかすぎるものであった。
特に、実施例と比較例３，４とは有機硫黄化合物の種類が異なる以外は同様の組成であるが、これらの加硫時間を比較すると、実施例に比べ比較例はいずれも長いことが確認された。
【００４５】
〔実施例６，比較例５〕
表２に示した組成のゴム用材料をニーダーにて混練し、所定のスラグを得た後、１６５℃の条件にて金型内で、加圧成形を行ない、直径４２．７ｍｍのワンピースゴルフボールを得た。
得られたワンピースゴルフボールについて、下記方法で加硫時間を測定した以外は上記ソリッドコアと同様にして初速と硬度を調べた。結果を表２に併記する。
加硫時間
ＪＳＲキュラストメータにて１６５℃で４５分間測定し、下記式のトルク値Ａまでの時間を加硫時間とした。
〔（最大トルク値−最小トルク値）×０．９〕＋最小トルク値＝Ａ
【００４６】
【表２】

[0001]
BACKGROUND OF THE INVENTION
The present invention is excellent in productivity of a solid core, a solid center (hereinafter collectively referred to as a center core) and a one-piece golf ball of a solid golf ball or a wound golf ball, and a composition capable of imparting high resilience and the composition. The golf ball having a high resilience obtained by the present invention will be described in more detail. For a golf ball that is suitable for pressure molding and has a suitable hardness and an excellent initial speed performance. The present invention relates to a rubber composition and a golf ball having high resilience formed using the rubber composition for a golf ball.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, rubber compositions for golf balls have been used as molding materials for center cores and one-piece golf balls used for solid golf balls and thread wound golf balls.
[0003]
Various improvements have been made to golf ball rubber compositions. For example, JP-A-11-262544 discloses a mercapto group in a composition such as a base rubber and a co-crosslinking agent. By blending organic sulfur compounds such as benzothiazol or thiadiazol with aromatics and aromatic thiophenols (such as pentadichlorothiophenol), the rubber composition is adjusted to a material suitable for injection molding with a low vulcanization rate. However, a method for manufacturing a rubber ball has been proposed.
[0004]
However, the organic sulfur compound in the above proposal is blended for the purpose of delaying the vulcanization speed in order to make the rubber composition suitable for injection molding, and the rubber composition is used for the golf ball rubber composition. When it is used for pressure molding usually adopted as a molding method, the vulcanization time is long and the productivity is deteriorated.
[0005]
The present invention has been made in view of the above circumstances, and is a rubber composition for a golf ball that can be suitably used for pressure molding of a solid golf ball, a center core of a wound golf ball, and a one-piece golf ball, and has an appropriate hardness. It is an object of the present invention to provide a rubber composition for a golf ball that can have a molded article with improved initial speed, and a golf ball having high resilience using the rubber composition for a golf ball.
[0006]
Means for Solving the Problem and Embodiment of the Invention
As a result of intensive studies to achieve the above object, the present inventor has (A) a base rubber, (B) a metal salt of an unsaturated carboxylic acid, and / or an unsaturated carboxylic acid and zinc oxide, (C) In the rubber composition for golf balls formed by blending an organic peroxide, with respect to 100 parts by mass of the base rubber, (D) general formula R-SH (wherein R is a carbon number of 3 A golf ball rubber composition comprising 0.1 to 5 parts by mass of a mercaptan represented by 1 to 25 linear or branched alkyl groups) is an organic sulfur compound. Mercaptans are blended, but the vulcanization rate does not decrease and is suitable for pressure molding, and the above-mentioned specific mercaptans can be molded under almost the same molding conditions and have an appropriate hardness And molded products with excellent initial speed performance And finding that it is reliably manufactured.
[0007]
And when the present inventors further examined, a golf ball having a center core formed of the rubber composition for golf balls and a one-piece golf ball formed of the composition have an appropriate hardness, The present inventors have found that the golf ball has an excellent rebound and has a ball structure, and have achieved the present invention.
[0008]
Therefore, the present invention provides the following golf ball rubber composition and golf ball.
Claim 1: Golf comprising (A) base rubber, (B) metal salt of unsaturated carboxylic acid and / or unsaturated carboxylic acid and zinc oxide, and (C) organic peroxide. In the ball rubber composition, (D) general formula R-SH (wherein R represents a linear or branched alkyl group having 3 to 25 carbon atoms) with respect to 100 parts by mass of the base rubber. A rubber composition for golf balls, comprising 0.1 to 5 parts by mass of a mercaptan represented by formula (1).
Claim 2: The rubber composition for a golf ball according to claim 1, wherein the mercaptan as the component (D) is selected from amyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, dodecyl mercaptan, stearyl mercaptan, octadecan mercaptan. object.
Claim 3: In a golf ball comprising a center core and at least one layer of cover, the center core is formed of the rubber composition for golf balls according to claim 1 or 2. A featured golf ball.
[4] The golf ball of [3], wherein the cover is multi-layered into two or more layers.
Claim 5: A one-piece golf ball formed of the rubber composition for a golf ball according to claim 1 or 2.
[0009]
Hereinafter, the rubber composition for golf balls of the present invention will be described in more detail with reference to (A) a base rubber, (B) a metal salt of an unsaturated carboxylic acid, and / or an unsaturated carboxylic acid and zinc oxide. , (C) an organic peroxide, and (D) a specific mercaptan as an essential component, and can be suitably used for any one-piece golf ball material, solid core material, and solid center material. It can be done.
[0010]
Here, as the base rubber of the component (A), polybutadiene which is used as a known rubber base for golf balls can be preferably used. Specifically, 1,4-cis polybutadiene, particularly cis 1,4-cis polybutadiene having a structure of at least 40% or more can be preferably used. In this base rubber, natural rubber, polyisoprene rubber, styrene butadiene rubber and the like can be used in combination with the above-mentioned polybutadiene if desired.
[0011]
The composition of the present invention contains (B) a metal salt of an unsaturated carboxylic acid and / or an unsaturated carboxylic acid and zinc oxide as essential components. The component (B) is used for the golf ball of the present invention. A component whose composition is selected according to a molded product produced by the composition. For example, when the golf ball composition of the present invention is used for a solid center material or a solid core material, a metal salt of an unsaturated carboxylic acid is used. When used as a one-piece golf ball material, an unsaturated carboxylic acid and zinc oxide are blended as essential components.
[0012]
Here, specifically, as the metal salt of unsaturated carboxylic acid, zinc methacrylate, zinc acrylate, or the like can be suitably blended, but zinc acrylate can be suitably used because of its particularly high resilience. The compounding amount of the metal salt of these unsaturated carboxylic acids is preferably 5 parts by mass or more, particularly 15 parts by mass or more, and the upper limit is 45 parts by mass or less, particularly 30 parts by mass or less with respect to 100 parts by mass of the base rubber. .
[0013]
As the unsaturated carboxylic acid, specifically, methacrylic acid, acrylic acid, and the like can be suitably blended, and methacrylic acid can be favorably used because of its particularly high durability. The amount of the unsaturated carboxylic acid is preferably 5 parts by mass or more, particularly 15 parts by mass or more, and 45 parts by mass or less, particularly 30 parts by mass or less as an upper limit with respect to 100 parts by mass of the base rubber.
[0014]
In blending the unsaturated carboxylic acid, it is essential to use zinc oxide in combination. The blending amount of zinc oxide is preferably 5 parts by mass or more, particularly 15 parts by mass or more, and the upper limit is 45 parts by mass or less, particularly 30 parts by mass or less with respect to 100 parts by mass of the base rubber.
[0015]
In addition to the above essential components, the solid core material, solid center material and one-piece solid golf ball material include, as an optional component, an unsaturated carboxylic acid, zinc oxide, one-piece as an optional component. The solid golf ball material can be mixed with a metal salt of an unsaturated carboxylic acid. Preferred examples of the unsaturated carboxylic acid and the metal salt of the unsaturated carboxylic acid include those mentioned above. The blending amount of the optional component can be appropriately selected within a range that does not affect the essential components.
[0016]
Examples of the organic peroxide of the component (C) of the present invention include 1,1-bis-t-butylperoxy-3,3,5-trimethylcyclohexane, dicumyl peroxide, di (t-butylperoxy). ) -Meta-diisopropylbenzene, 2,5-dimethyl-2,5-di-t-butylperoxyhexane and the like. The blending amount can be 0.2 parts by mass or more, particularly 0.5 parts by mass or more, and 5 parts by mass or less, particularly 2 parts by mass or less as an upper limit with respect to 100 parts by mass of the base rubber. One organic peroxide can be used alone, or two or more organic peroxides can be mixed and used.
[0017]
The rubber composition for a golf ball of the present invention has an essential requirement that a mercaptan represented by the general formula R-SH is blended as the component (D).
[0018]
Here, R in the general formula is a monovalent hydrocarbon group excluding an aromatic group having 3 to 25 carbon atoms, particularly 7 to 20 carbon atoms, and more specifically, a linear or branched alkyl group or An alkenyl group.
[0019]
Specific examples of the mercaptan of the component (D) of the present invention include amyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, dodecyl mercaptan, stearyl mercaptan, octadecan mercaptan and the like, particularly t-nonyl mercaptan, stearyl mercaptan. Is preferred.
[0020]
In the present invention, the compounding amount of the mercaptans is 0.1 parts by mass or more, particularly 0.3 parts by mass or more, and 5 parts by mass or less, particularly 2 parts by mass or less as an upper limit with respect to 100 parts by mass of the base rubber. It is necessary to blend, and by using within these ranges, in combination with the above essential components, a decrease in vulcanization rate and a decrease in hardness of the molded product itself are suppressed, and an excellent initial speed for the molded product Performance and resilience are added. If the blending amount is small, the initial speed of the molded product cannot be improved.If the blending amount is large, the vulcanization rate is lowered and the productivity is lowered, and the hardness and resilience of the resulting molded product are greatly decreased. End up.
[0021]
The composition of the present invention comprises (A) a base rubber, (B) a metal salt of an unsaturated carboxylic acid, and / or an unsaturated carboxylic acid and zinc oxide, (C) an organic peroxide, (D) specific The mercaptans are blended as essential components, and various additives can be blended as necessary. Here, when using a filler, for example, barium sulfate, calcium carbonate and the like can be blended, and the blending amount of these fillers is usually in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the base rubber. It can be used for adjusting the specific gravity.
[0022]
In order to obtain the rubber composition for a golf ball of the present invention, the above-described materials may be kneaded according to a conventional method. For example, a method of kneading the above materials with a Banbury mixer, a kneader or the like can be employed.
[0023]
When the golf ball rubber composition is formed into a molded product, it can be produced by pressure molding in the same manner as the production of a known center core and one-piece golf ball. And put the created slag in a predetermined mold, 140 ° C. or higher, particularly 150 ° C. or higher, the upper limit is 180 ° C. or lower, especially 165 ° C. or lower, 10 minutes or longer, especially 15 minutes or longer, the upper limit is 60 minutes or less, In particular, it is possible to employ a method of vulcanizing and pressure forming within 30 minutes. The composition of the present invention can employ the same vulcanization time as when a conventional rubber composition is used.
[0024]
Next, as long as the golf ball of the present invention is formed by using the golf ball composition of the present invention, there is no limitation on the mode thereof, and specifically, for the golf ball of the present invention. One-piece golf ball formed only by the composition, two-piece golf ball formed by covering the solid core formed by the composition for golf ball of the present invention with a cover, multi-piece golf ball having three or more pieces, and golf ball of the present invention Various golf balls such as a thread-wound golf ball having a solid center formed of the composition for use can be exemplified.
[0025]
When the golf ball of the present invention is a two-piece solid golf ball comprising a solid core and a single layer cover, the golf of the present invention contains a metal salt of an unsaturated carboxylic acid as a component (B). It is manufactured using a rubber composition for balls. In this case, the composition can be manufactured by employing a pressure molding method.
[0026]
The diameter of the solid core of the present invention can be usually 30 mm or more, particularly 35 mm or more, the upper limit is 41 mm or less, particularly 39 mm or less, and the weight is usually 20 g or more, particularly 30 g or more, and the upper limit is 40 g or less, particularly 37 g or less. can do.
[0027]
The solid core formed from the composition of the present invention has a very high resilience and has a high initial velocity even when the hardness is low, as compared with a solid core formed from a normal golf ball rubber composition. . The hardness of the solid core is not particularly limited, but the deformation amount of the ball under a heavy load of 100 kg is usually 2.0 mm or more, particularly 2.5 mm or more, and the upper limit is 5.0 mm or less, especially 4. It can be 0 mm or less. When the amount of deformation is small, the hit feeling is deteriorated, and when the amount is large, the resilience may be lowered.
[0028]
In the solid golf ball of the present invention, a cover is formed on the solid core, and the cover can be formed using a known cover material. Specific examples of the cover material include ionomer resins, balata rubber, polyurethane elastomers, polyamide elastomers, polyester elastomers, and the like.
[0029]
As a method of covering the solid core with a cover, a known cover forming method can be employed, and examples thereof include injection molding and compression molding. For example, when injection molding is performed, a solid core prepared in advance is placed in a predetermined mold, and a cover material is injected according to a conventional method. When compression molding is performed, a pair of half cups made of cover material is used. The method of encapsulating the solid core and pressing in a predetermined mold can be employed.
[0030]
It is recommended that the thickness of the cover of the present invention is usually 0.5 mm or more, preferably 1.0 mm or more, and the upper limit is 4 mm or less, preferably 2.5 mm or less. If the cover is thin, the durability may be reduced. If the cover is thick, the resilience may be reduced.
[0031]
When the golf ball of the present invention is a solid golf ball, in addition to the two-piece solid golf ball described above, a three-piece or more multi-piece golf ball in which a core or a cover is multilayered into two or more layers may be used. Also in the case of obtaining a modified golf ball, it can be manufactured according to a known method using the core material and the cover material described above.
[0032]
When the golf ball of the present invention is a thread wound golf ball having a solid center, the rubber composition for a golf ball of the present invention containing a metal salt of an unsaturated carboxylic acid as the component (B) in the same manner as the solid core. Create a solid center.
[0033]
The diameter of the solid center of the present invention can be usually 25 mm or more, particularly 28 mm or more, and the upper limit is 38 mm or less, particularly 33 mm or less. Also, the weight can be 15 g or more, particularly 20 g or more, and the upper limit can be 30 g or less, particularly 25 g or less. If the weight of the solid center is small, the flight distance is reduced, and if it is large, the standard in the golf rules may be exceeded. .
[0034]
The hardness of the solid center is not particularly limited, but the deformation amount of the ball under a heavy load of 100 kg is usually 1 mm or more, particularly 1.5 mm or more, and the upper limit is 10 mm or less, particularly 6 mm or less. it can. When the amount of deformation is small, the hit feeling is lowered, and when the amount is large, the productivity of the wound ball may be lowered.
[0035]
In order to use the solid center as a thread-wound core, a known method can be employed. For example, a thread rubber formed of polyisoprene can be wound with a predetermined random winding. The cover can be formed by using the same materials and methods as those used for the solid golf ball cover.
[0036]
When the golf ball of the present invention is a one-piece golf ball, the rubber composition for a golf ball of the present invention containing an unsaturated carboxylic acid and zinc oxide as the component (B) is prepared, and in accordance with the pressure molding conditions of the above composition It can be manufactured by employing a pressure molding method of molding in a predetermined one-piece golf ball mold.
[0037]
In addition, the golf ball of the present invention can be formed with a diameter and a weight of 42.67 mm or more and 42.75 mm or less and a weight of 45.2 g or more and 45.93 g or less according to the golf regulations.
[0038]
【The invention's effect】
The rubber composition for a golf ball of the present invention is suitable for pressure molding, has excellent productivity without lowering the vulcanization speed, has a suitable hardness, and can obtain a molded product with high resilience. In addition, the golf ball of the present invention is formed of the above composition and has excellent resilience.
[0039]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.
[0040]
[Examples 1 to 5, Comparative Examples 1 to 4]
A rubber material having the composition shown in Table 1 was kneaded with a kneader to obtain a predetermined slag, and then pressure-molded in a mold at 155 ° C. to obtain a solid core having a diameter of 38.7 mm. Obtained.
About the obtained solid core, various performance was investigated as follows. The results are shown in Table 1.
Deflection amount of solid core when core hardness is 100kg heavy load. It shows that it is so soft that a numerical value is large.
Core initial speed Measured with an initial speedometer of the same type as the official agency USGA.
Vulcanization time Measured with a JSR curast meter at 155 ° C. for 30 minutes, and the time until the torque value A of the following formula was determined as the vulcanization time.
[(Maximum torque value−minimum torque value) × 0.9] + minimum torque value = A
[0041]
[Table 1]

[0042]
From the results of Table 1, the solid cores formed with the rubber composition for golf balls of the present invention can be molded with a vulcanization time in which pressure molding can be employed, and have an appropriate hardness and excellent initial speed performance. It was a thing.
[0043]
On the other hand, Comparative Examples 1 and 2 were inferior to the Examples in initial speed performance.
In particular, when Example and Comparative Example 1 are compared, the composition is the same except for the presence or absence of t-nonyl mercaptan, and the Examples have slightly lower core hardness (deformation amount) than Comparative Example 1, but both are comparative. It was confirmed that the initial speed performance was superior to that of Example 1.
[0044]
The core materials of Comparative Examples 3 and 4 contained a small amount of an aromatic sulfur compound, but the initial speed was slow and the hardness was too soft.
In particular, the examples and comparative examples 3 and 4 have the same composition except that the types of organic sulfur compounds are different, but when these vulcanization times are compared, it is confirmed that all of the comparative examples are longer than the examples. It was done.
[0045]
[Example 6, Comparative Example 5]
A rubber material having the composition shown in Table 2 was kneaded in a kneader to obtain a predetermined slag, and then pressure-molded in a mold at 165 ° C. to form a one-piece golf ball having a diameter of 42.7 mm. Got.
About the obtained one-piece golf ball, initial velocity and hardness were examined in the same manner as the solid core except that the vulcanization time was measured by the following method. The results are also shown in Table 2.
Vulcanization time Measured with a JSR curast meter at 165 ° C. for 45 minutes, and the time until the torque value A of the following formula was determined as the vulcanization time.
[(Maximum torque value−minimum torque value) × 0.9] + minimum torque value = A
[0046]
[Table 2]

Claims (5)

  A rubber composition for a golf ball comprising (A) a base rubber, (B) a metal salt of an unsaturated carboxylic acid, and / or an unsaturated carboxylic acid and zinc oxide, and (C) an organic peroxide. In the product, with respect to 100 parts by mass of the base rubber, (D) represented by the general formula R-SH (wherein R represents a linear or branched alkyl group having 3 to 25 carbon atoms) A rubber composition for a golf ball, comprising 0.1 to 5 parts by mass of a mercaptan.   The rubber composition for a golf ball according to claim 1, wherein the mercaptan as the component (D) is selected from amyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, dodecyl mercaptan, stearyl mercaptan, and octadecan mercaptan.   A golf ball comprising a center core and at least one layer of a cover, wherein the center core is formed of the rubber composition for a golf ball according to claim 1 or 2. ball.   4. The golf ball according to claim 3, wherein the cover is multi-layered into two or more layers.   A one-piece golf ball comprising the rubber composition for a golf ball according to claim 1 or 2.