JPH0530473B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a cover composition for a golf ball and a golf ball obtained from the same. (Prior Art) There are two commonly used golf balls: thread-wound golf balls and two-piece golf balls. Two-piece golf balls are often used by amateur golfers, and because they have little spin when hit and a high launch angle, the trajectory of the ball after hitting does not feel like it hops midway through, making it a so-called stick ball. If you draw a trajectory like this, there will be more rolling after falling to the ground, increasing flight distance. Two-piece golf balls also have excellent durability. However, professional golfers and amateur players with a handicap of 10 or less who have a fast head speed prefer to use thread-wound golf balls. A thread-wound golf ball has a longer contact time between the club face and the ball, is more likely to spin than a two-piece golf ball, and has relatively little rolling after falling, improving the accuracy of the ball. Also, it is easy to apply intentional lifting and slicing. Therefore, it is often used because it is easy to control the ball and the impact force when hitting is small. However, such thread-wound golf balls are inferior to two-piece golf balls in terms of flight distance and durability. Recently, the number of dimples on the surface of a golf ball has been
So-called multi-dimples, which have 380 or more dimples, have become mainstream. This means that the trajectory of the ball after it is hit (ball trajectory) is better with multi-dimples than with conventional balls with 300 to 360 dimples.
The ball becomes more ball-like, like a two-piece ball, with more runs and better flight. In addition, a ball that flies like a stick ball is less affected by wind, and there is less loss in distance due to headwinds. This multi-dimple method is also used in thread-wound golf balls, resulting in balls that have a long flight distance and have a lot of runs. (Problems to be Solved by the Invention) Although thread-wound golf balls employing such a multi-dimple system can increase flight distance, they are inferior in controllability inherent to thread-wound golf balls. That is, if priority is given to flight distance, the inherent good controllability of a thread-wound golf ball is lost, and conversely, if good controllability is pursued, a reduction in flight distance is inevitable. Therefore, it is conceivable to provide good controllability to a thread-wound golf ball employing the multi-dimple system. For example, the depth of the dimples can be adjusted to improve controllability, that is, to make the ball run less and stop more easily, but in this case, the flight distance is significantly reduced. It is also possible to improve this defect from the cover material. The repulsion characteristics and spin function of a golf ball vary greatly depending on the cover material. Generally, high styrene resin and natural rubber are added as polymer components to a cover whose main component is transpolyisoprene.
-31744). Although this cover has good cut resistance in the summer, its repulsion properties deteriorate.
Also, because the cover has high hardness, it is difficult to spin. It is conceivable to add natural rubber to the conventional balata cover to lower the cover hardness and improve spin performance, but this would result in poor cut resistance and poor moldability. JP-A-61-16753 discloses a cover system in which trans-1,4-polybutadiene is blended with a balata cover, but since the hardness of the cover decreases, it becomes easier to spin, but on the other hand, it has poor cut resistance. Not sexual enough. In addition, since it has a high melting point, if more than 30% trans polybutadiene is blended, the fluidity during ball molding will be poor, and penetration (penetration of the cover material into the gaps between the thread rubber layers) will be poor.
The outer diameter of the ball increases. In addition, impact resistance also deteriorates. If the press temperature is increased during molding, the rubber thread will undergo thermal deterioration and its resilience properties will also decrease. Therefore, there is a need for a cover material that maximizes the performance of the multi-dimple type golf ball. (Means for solving the problem) That is, the present invention adds 5 to 42 parts by weight of trans polybutadiene, 1 to 15 parts by weight of fine fibers having an amide group, and 100 parts by weight of a cover material containing trans polyisoprene as a main component. A golf ball cover composition containing 5 to 30 parts by weight of natural rubber is provided. Furthermore, the present invention provides a thread-wound golf ball consisting of a thread-wound core and a cover, in which the cover contains 100 parts by weight of a cover material whose main component is trans-polyisoprene, 5-42 parts by weight of trans-polybutadiene, and 1-15 parts by weight of fine fibers having an amide group. To provide a thread-wound golf ball, which contains 5 to 30 parts by weight of natural rubber and 5 to 30 parts by weight of natural rubber, and has 380 to 510 dimples on the surface of the golf ball. Natural or synthetic trans-
A so-called balata cover made of 1,4-polyisoprene is used. Various conventionally known balata cover materials can be used. Any conventionally known transpolybutadiene may be used. Preferably, the trans polybutadiene has 85% or more of trans bonds, a weight average molecular weight of 30,000 to 300,000, and a molecular weight distribution (weight average molecular weight/number average molecular weight) of 1.2 to 5.0. Molecular weight and molecular weight distribution are determined by gel permeation chromatography (GPC) using styrene standards.
If the weight average molecular weight is less than 30,000, impact resistance will decrease, and if it exceeds 300,000, processing and moldability will deteriorate. This trans polybutadiene is a balata cover material 100%
It is added in an amount of 5 to 42 parts by weight, preferably 10 to 30 parts by weight. If it is less than 5 parts by weight, the hardness of the ball increases and good spin characteristics cannot be obtained. If it exceeds 42 parts by weight, the hardness decreases too much and sufficient durability cannot be obtained. Examples of fine fibers having an amide group include nylon fibers (such as nylon 6, nylon 610, nylon 12, nylon 611, and nylon 612) with a melting point of 190 to
225°C, preferably 200 to 220°C), or block copolymers of nylon and other polymers (nylon and liquid diene block copolymers). The fine fibers preferably have an average diameter of 0.05 to 0.8μ and a shortest fiber length in a circular cross section of 1μ or more, preferably 8μ or more. The fine fibers are generally incorporated into the balata cover material in a premixed mixture with other rubber components that are compatible with the transpolyisoprene. Examples of other rubber components that are compatible with transpolyisoprene include natural rubber, styrene-butadiene rubber, and cis-polyisoprene.
1,4-polybutadiene, trans-1,4-polybutadiene, 1,2-polybutadiene,
Examples include EPDM and NBR. Among these, natural rubber, which has extremely good processability, is most preferred. The amount of fine fibers to be blended is 1 to 15 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of the balata cover material. If the amount is less than 1 part by weight, the cut resistance will not improve, and if it exceeds 15 parts by weight, the impact resistance will deteriorate and the hardness of the cover will increase too much, resulting in poor feel when hitting the ball. Preferably, the fine fibers are grafted with other rubber components that are compatible with the transpolyisoprene. The graft bonding may be carried out, for example, via an alkyl phenol formaldehyde resin or a condensate of a novolak type phenol formaldehyde resin. The alkylphenol formaldehyde resin includes, for example, a resol-type initial condensate obtained by reacting an alkylphenol such as cresol with formaldehyde or acetaldehyde in the presence of an alkali solvent, and modified products thereof. In particular, alkylphenol formaldehyde resins having two or more methylol groups in the molecule are preferably used. As an alkyl phenol formaldehyde resin, for example, the initial condensate of a novolak type phenol formaldehyde resin is a mixture of phenols such as phenol and bisphenols and formaldehyde (paraformaldehyde may also be used).
These are soluble and fusible resins obtained by a homocondensation reaction, and modified products thereof. In the case of using the above-mentioned phenol formaldehyde resin, the graft bond is between the hydrogen atom of the methylene group in the polymer molecule of the other rubber component and the methylol in the phenol formaldehyde resin molecule. It is thought to be produced by a dehydration reaction with hydroxyl groups and a dehydration reaction between the hydrogen atoms of the amide groups of the amide group-containing fine fibers and the remaining methylol hydroxyl groups of the phenol formaldehyde resin bonded to the other rubber components. A method for manufacturing such a mixture of other rubbers and fine fibers having amide groups is disclosed in Japanese Patent Application Laid-Open No. 1986-
Publication No. 79037, Japanese Patent Application Publication No. 1983-43041, Japanese Patent Application Publication No. 1983
It is described in detail in Japanese Patent Laid-Open No. 19343-19343 and Japanese Patent Application Laid-open No. 1934-1988. Such a mixture is preferably available from Ube Industries, Ltd. under the name FRR. 5 to 5 parts of natural rubber per 100 parts by weight of balata cover
It is blended in an amount of 30 parts by weight, preferably 10 to 26 parts by weight.
When the nylon short fibers are supplied in a mixed form with natural rubber, the amount of natural rubber includes the above-mentioned short nylon fibers. If the natural rubber content is 5% by weight or less, the hardness of the cover will improve and the spin performance will deteriorate. If it exceeds 30% by weight, the hardness of the cover will decrease. The cover material of the present invention may contain a high styrene resin. The amount of high styrene resin blended is 15% by weight or less. High styrene resin is a styrene-butadiene copolymer with a high styrene content and is in the form of a resin. If the addition of high styrene resin exceeds 15% by weight, the repulsion properties will deteriorate. Addition of high styrene resin improves cut resistance. Other additives such as fillers (zinc oxide, titanium oxide, stearic acid, red iron, etc.), vulcanization accelerators (such as secondary amines), and sulfur may be added to the cover composition of the present invention. good. Methods for manufacturing golf balls using the above-mentioned cover compositions are conventionally known. For example, it can be obtained by wrapping a rubber thread around a rubber ball called a center or around a rubber ball filled with liquid, covering the outside with the coating material of the present invention, and vulcanizing it. The golf ball cover material of the present invention may be applied to conventional golf balls having 300 to 360 dimples, but is preferably applied to so-called multi-dimple type golf balls having 380 or more dimples. In the case of a multi-dimple type golf ball, the trajectory of the ball after being hit takes on the shape of a so-called two-piece golf ball, and it flies well.
In addition, when covered with the golf ball cover material of the present invention, there are disadvantages when using a multi-dimple system (for example, the ball rolls too much on the green and is difficult to stop, or the ball cannot be used with the conventional spin rate due to the intentional The drawbacks (such as difficulty in hooking and slicing, poor controllability, etc.) have been greatly improved, and while maintaining the long flight distance obtained with the multi-dimple method, the amount of spin is high, and the controllability when hitting iron shots has been greatly improved. You get the ball. (Effects of the Invention) According to the present invention, the drawbacks of conventional golf balls,
That is, poor durability and cut resistance can be greatly improved by incorporating fine fibers, and when the golf ball cover material of the present invention is applied to a multi-dimple type golf ball, it has excellent spin performance. , it is possible to obtain a golf ball with excellent controllability and less run, even though it has a long flight distance. Particularly, when hitting an iron shot, a golf ball that stops on the green can be obtained. (Example) The present invention will be explained in more detail with reference to Examples. Examples 1 and 2 and Comparative Examples 1 to 4 The cover components shown in Table 1 were thoroughly kneaded using an open roll. In addition to the components shown in Table 1, 5 parts by weight of zinc oxide, 1.2 parts by weight of secondary amine, 15 parts by weight of titanium oxide, and 1.5 parts by weight of sulfur were added and thoroughly kneaded. A pair of hemispherical shells molded from this cover material are wrapped around a 28.5 mm diameter liquid core (fluid sealed in a rubber bag) with rubber thread to create a thread winder with a diameter of approximately 39.5 mm. Cover over the core ball, approx. 85
After pressing at ℃ to form a large ball, gas vulcanization was performed using carbon disulfide for 48 hours. The golf ball was finished with a paint finish using a standard method, and the physical properties of the golf ball were examined. The results are shown in Table-1.

【table】

[Table] Comparative Examples 1 and 2 are trans-1,4-
Contains a large amount of polybutadiene and has poor cut resistance and impact resistance. The material shown in Comparative Row 3 contains only high styrene and has poor repulsion characteristics. Comparative Example 4 contains nylon fibers and is inferior in face scratches. Examples 3 and 4 and Comparative Examples 5 to 7 Golf balls were prepared as in Example 1 using the formulations shown in Table 2, and their physical properties were examined. The results are shown in Table-2.

【table】

[Table] Compared to the comparative example, the golf ball of the present invention had improved spin and reduced run.
It can be seen that the flying distance of the carry has increased.

Claims (1)

[Claims] 1. 100 parts by weight of a cover material whose main component is trans polyisoprene, and 5 to 5 parts by weight of trans polybutadiene.
A golf ball cover composition containing 42 parts by weight, 1 to 15 parts by weight of fine fibers having an amide group, and 5 to 30 parts by weight of natural rubber. 2 Fine fibers have an average diameter of 0.05 to 0.8μ and a shortest fiber length of 1μ.
2. The cover composition according to item 1, having the above. 3. The cover composition according to item 1, wherein the fine fibers are blended into the cover material in the form of a kneaded product of transpolyisoprene and other compatible rubber components. 4. The cover composition according to item 3, wherein the fine fibers are graft-bonded with other rubber components in the kneaded product. 5. The cover composition according to any one of items 1 to 4, wherein the composition further contains 15% by weight or less of high styrene resin. 6. In a thread-wound golf ball consisting of a thread-wound core and a cover, the cover contains 100 parts by weight of a cover material whose main component is trans polyisoprene, 5 to 42 parts by weight of trans polybutadiene, 1 to 15 parts by weight of fine fibers having an amide group, and A thread-wound golf ball comprising 5 to 30 parts by weight of natural rubber and having 380 to 510 dimples on the surface of the golf ball. 7 Fine fibers have an average diameter of 0.05 to 0.8μ and a shortest fiber length of 1μ.
7. The thread-wound golf ball according to item 6, which has the above. 8. The thread-wound golf ball according to item 6, wherein the fine fibers are blended into the cover in the form of a kneaded product of transpolyisoprene and other compatible rubber components. 9. The thread-wound golf ball according to item 8, wherein the fine fibers are graft-bonded with other rubber components in the kneaded product. 10 The composition further contains 15% by weight of high styrene resin.
The thread-wound golf ball according to any one of items 6 to 9, which contains the following: