JP2699257B2 - Golf ball - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball. More specifically, the present invention relates to a golf ball having high repulsion performance and good feeling when hitting a ball.

[0002]

2. Description of the Related Art A golf ball having a vulcanized molded product of a rubber composition as a core is called a solid golf ball and has a high rebound performance and a superior flight performance as compared with a thread-wound golf ball. There is a problem that the feeling is hard and bad.

[0003] For this reason, US Pat. No. 5,050,886 discloses that the inner core matrix is blended with a particle size of 0.8 to 7.0 m.
It has been proposed that a vulcanized rubber powder of m is blended to reduce the impact force at the time of hitting a ball to improve feeling.

[0004]

However, in the above-mentioned U.S. Patent, the rebound performance is reduced by the addition of the vulcanized rubber powder, and the flight distance is smaller than that of the comparative example in which the vulcanized rubber powder is not added. . In addition, no other case has been reported in which the blending of the vulcanized rubber powder dramatically improved the flight distance.

[0005] This is considered to be related to the fact that the conventional compounding of the vulcanized rubber powder has been carried out with resource recycling in mind.

In the present invention, the compounding of a vulcanized rubber powder that prioritizes high repulsion over recycling and cost reduction improves the flight distance and the feeling at the time of hitting, which are the desires of golf players. It is an object of the present invention to provide a golf ball that can achieve the above.

[0007]

According to the present invention, a metal salt of an α, β-unsaturated fatty acid is added to 100 parts by weight of a diene rubber.
The core matrix compound containing 5 parts by weight or more contains 25 parts by weight or less of α, β-unsaturated fatty acid metal salt with respect to 100 parts by weight of the diene rubber, and the average particle size before compounding is 0.8 mm.
The following vulcanized rubber powder was mixed with rubber 1
By blending 35 to 200 parts by weight with respect to 00 parts by weight, a golf ball having high repulsion performance and good feeling when hitting a ball is provided.

In the present invention, the reason why the compounding of the above-mentioned vulcanized rubber powder brings high repulsion performance and good feeling to the golf ball is not always clear at present, but the compounded vulcanized rubber powder is an inner core matrix. The softer, softer vulcanized rubber powder inhibits the formation of α, β-unsaturated fatty acid metal salt homopolymers (conjugates) that make the golf ball harder, and the fine vulcanized rubber powder is contained in the inner core matrix. A well-dispersed rubber that enhances repulsion performance, a strong matrix network of α, β-unsaturated fatty acid metal salt and a soft vulcanized rubber powder are present in a well-balanced manner.
It is considered that the golf ball has a high repulsion performance and a good feeling by achieving high repulsion and relaxation of impact force.

Hereinafter, the progress of completing the present invention and the significance of the requirements constituting the present invention will be described in detail.

The present inventors have previously found that the smaller the loss tangent at −50 ° C., the better the rebound performance. Therefore, as a result of various attempts to minimize the loss tangent at −50 ° C., if the amount of the α, β-unsaturated fatty acid metal salt used for vulcanization (crosslinking) is increased, the content at −50 ° C. It has been found that the loss tangent is reduced and the rebound performance is improved.

However, if the amount of the α, β-unsaturated fatty acid metal salt is more than 50 parts by weight with respect to 100 parts by weight of the rubber component, the repulsion performance is remarkably improved, but the impact force at the time of hitting the ball becomes large. The feeling becomes significantly worse.

Therefore, the present inventors have attempted to improve the feel at the time of hitting a ball while maintaining the high repulsion performance achieved by blending a large amount of a metal salt of an α, β-unsaturated fatty acid. The idea was to mix the vulcanized rubber powder that had been pulverized.

In order to improve the feel at the time of hitting the ball, a soft vulcanized rubber powder should be blended, and the composition thereof is blended with an inner core matrix (in the present specification, the blended inner core is a base rubber of the inner core. Vulcanized rubber having an average particle diameter of 0.8 mm, which is the same compounding system as in (1) above, and which contains not more than 25 parts by weight of α, β-unsaturated fatty acid metal salt per 100 parts by weight of diene rubber The pulverized vulcanized rubber powder is suitable below.

In this vulcanized rubber powder, α, β-unsaturated fatty acid metal salt is added in an amount of 2 parts per 100 parts by weight of diene rubber.
The reason for setting the content to 5 parts by weight or less is that if the content of the α, β-unsaturated fatty acid metal salt is larger than that, the hardness of the vulcanized rubber powder itself is increased, and the feeling at the time of hitting the ball is difficult to be improved. is there. As the content of the α, β-unsaturated fatty acid metal salt decreases, the softness increases, but if it is too soft, repulsion performance may decrease. As described above, the content is preferably 25 parts by weight or less and 10 parts by weight or more based on 100 parts by weight of the diene rubber. However, when the content of the α, β-unsaturated fatty acid metal salt in the inner core matrix is large, the vulcanized rubber powder may not contain the α, β-unsaturated fatty acid metal salt at all.

The amount of the vulcanized rubber powder is 35 to 200 parts by weight, preferably 40 to 100 parts by weight, based on 100 parts by weight of the rubber in the inner core matrix. If the compounded amount of the vulcanized rubber powder is less than the above range, the feel at the time of hitting is not sufficiently improved, and if the compounded amount of the vulcanized rubber powder is larger than the above range, the repulsion performance is reduced, and the flight distance is reduced. There is a possibility that it will decrease, and the durability will also deteriorate.

A rubber composition containing 35 parts by weight or more of a metal salt of an α, β-unsaturated fatty acid with a diene rubber such as butadiene rubber is suitable for the inner core matrix.
In this inner core matrix compounding, the content of the α, β-unsaturated fatty acid metal salt is set to 35 parts by weight or more with respect to 100 parts by weight of the diene rubber. When compounding sulfur rubber powder,
This is to prevent the high repulsion performance from being impaired.
And, as the content of the α, β-unsaturated fatty acid metal salt increases, the rebound performance increases, and therefore, the flight distance also increases. The feeling at the time of hitting is not improved, and the durability is lowered by a large amount of the vulcanized rubber powder.
It is preferably at least 5 parts by weight and at most 90 parts by weight.

As described above, when a rubber composition for an inner core containing a vulcanized rubber powder is vulcanized and molded to produce an inner core, the repulsion performance of the inner core itself is improved, so that the flight distance is improved. The impact force at the time was reduced and the feeling was good.

[0018] However, when the inner core is produced only by blending the inner core matrix without blending the vulcanized rubber powder, a considerable improvement in flight distance can be achieved, but the impact force upon hitting the ball is large and the feeling is poor. Was.

As described above, when the vulcanized rubber powder is blended, the impact force at the time of hitting the ball is reduced and the feeling becomes better than when only the inner core matrix without the vulcanized rubber powder is blended. Moreover, the improved high repulsion performance did not decrease due to the large amount of the α, β-unsaturated fatty acid metal salt.

[0020] Therefore, unlike the conventional core composition generally used, high rebound (improvement of flight distance) and improvement of feeling can be achieved at the same time.

Here, the reason why the compounding of the vulcanized rubber powder enables the golf ball to have a high repulsion performance and a good feeling can be explained again as follows.

When a vulcanized rubber powder is not compounded, a large amount of α, β-unsaturated fatty acid metal salt is compounded to
A strong matrix network of the rubber and the α, β-unsaturated fatty acid metal salt is formed, and the repulsion performance is enhanced. However, the homopolymer (combination) of the α, β-unsaturated fatty acid metal salts formed simultaneously is formed. Therefore, the ball becomes very hard.

However, when the vulcanized rubber powder is compounded,
Since the vulcanized rubber powder has a smaller amount of the α, β-unsaturated fatty acid metal salt than the inner core matrix and is soft, the soft vulcanized rubber powder is a homopolymer of the α, β-unsaturated fatty acid metal salt which hardens the ball. Inhibits the formation and disperses the fine vulcanized rubber powder in the inner core matrix.Therefore, a strong matrix network and soft vulcanized rubber powder exist in a well-balanced manner, achieving high repulsion and relaxation of impact force. It is thought that it becomes. Further, the flight distance is improved by the high repulsion, and the feeling is improved by relaxing the impact force, so that a good feeling can be obtained.

The vulcanized rubber powder to be used must have an average particle size of 0.8 mm or less before blending into the inner core matrix in order to improve dispersibility in the inner core matrix. 5 mm or less is preferable. In terms of improving the dispersibility, the smaller the particle size of the vulcanized rubber powder, the better, but if the particle size is too small, the vulcanized rubber will burn during pulverization, or cause an increase in pulverization cost. An average particle size of 0.05 mm or more is practical.

The α, β-unsaturated fatty acid metal salts used for blending the inner core matrix and preparing the vulcanized rubber powder include, for example, α, β-unsaturated acids such as acrylic acid and methacrylic acid.
Metal salts such as zinc salts and magnesium salts of unsaturated fatty acid metal salts. These α, β-unsaturated fatty acid metal salts are mixed with α, β-unsaturated fatty acid and a metal compound such as zinc oxide at the time of compounding. In the form of α, β-
It may be an unsaturated fatty acid metal salt.

A preferred example of blending the inner core matrix is as follows. For example, 35 to 90 parts by weight of a metal salt of an α, β-unsaturated fatty acid, 0.2 part by weight of peroxide and 100 parts by weight of a diene rubber ~ 1.0 parts by weight, and 0-20 parts by weight of a filler, and further, if necessary, chemicals such as antioxidants, additives, vulcanization aids such as stearic acid and palmitic acid. It is. Further, an adhesive may be blended to improve the adhesiveness of the interface with the vulcanized rubber powder.

As the diene rubber compounded with the inner core matrix, butadiene rubber is suitable, and one having a cis content of 40% or more, particularly preferably 80% or more, is preferred.

As the α, β-unsaturated fatty acid metal salt, various ones can be used as described above.
Zinc salts such as zinc acrylate and zinc methacrylate are particularly preferred.

The peroxide acts as an initiator for vulcanization (crosslinking). Examples of the peroxide include dicumyl peroxide and 1,1-bis-3,3,5.
Although various substances such as trimethylcyclohexane can be used, dicumyl peroxide is particularly preferred in the present invention.

The amount of the peroxide used is diene rubber 1
If the amount is less than 0.2 part by weight, the vulcanization becomes insufficient. If the amount is more than 1.0 part by weight, the inner core becomes hard and the impact force becomes large. 0.2 to 1.0 part by weight is suitable for 100 parts by weight of rubber. In particular, 0.3 parts by weight is particularly suitable from the viewpoint of the balance between repulsion performance and impact force.

Various fillers such as zinc oxide, barium sulfate and silica can be used as the filler, but zinc oxide is particularly preferred in the present invention.

The rubber composition for preparing the vulcanized rubber powder has the same compounding system as the compound of the inner core matrix, and includes a diene rubber, a metal salt of α, β-unsaturated fatty acid, a peroxide, a filler, and other components. The same chemicals as in the case of the inner core matrix are used, and the compounding amount of the inner core matrix is also different except that the compounding amount of the α, β-unsaturated fatty acid metal salt and the compounding amount of the filler are different. It is almost the same as the case.

That is, as a rubber composition for producing a vulcanized rubber powder, for example, 0 to 25 parts by weight of a metal salt of an α, β-unsaturated fatty acid, 100 parts by weight of a diene rubber, 0.2 to 1.0 parts by weight, filler 5 to 35
It is suitable to mix parts by weight and the like, and further, if necessary, mix chemicals such as an antioxidant, an additive and a vulcanization aid.

Regarding diene rubbers, metal salts of α, β-unsaturated fatty acids, peroxides, fillers, and other compounding chemicals, the preferable ones are the same as those in the case of the inner core matrix.

[0035]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

Examples 1 to 9 and Comparative Examples 1 to 7 First, in order to obtain the vulcanized rubber powder used in the Examples and Comparative Examples, zinc acrylate was used as a metal salt of an α, β-unsaturated fatty acid. The rubber compositions A to D described in were prepared. The amounts shown in the table are parts by weight. This is described later
The same applies to Tables 2 to 4.

[0037]

[Table 1]

The rubber composition prepared by the above-mentioned compounding composition was
The mixture was vulcanized at 60 ° C. for 30 minutes, and the obtained vulcanized rubber was pulverized to obtain a vulcanized rubber powder.

When indicating the type of the obtained vulcanized rubber powder, it is indicated by a combination of the composition (A, B, C, D) of the rubber composition and the average particle size.

In terms of composition, A, B and C fall within the scope of the present invention, and those having an average particle size of 0.8 mm or less fall within the scope of the present invention.

In this specification, as shown in FIG. 1, the average particle size of the vulcanized rubber powder is obtained by measuring the horizontal diameter x and the vertical diameter y of the vulcanized rubber powder 1 and calculating The particle size is determined according to the formula of (x + y) / 2, and the average value of the particle sizes of 100 vulcanized rubber powders is defined as the average particle size.

Next, the vulcanized rubber powder obtained as described above was blended into an inner core matrix formulation shown in Tables 2 to 4 to prepare a rubber composition for an inner core. It was filled in a mold and vulcanized at 160 ° C. for 30 minutes to obtain an inner core having a diameter of 38.5 mm.

Around the inner core obtained as described above,
Injection molding was carried out on a composition for a skin in which 2 parts by weight of titanium dioxide was added to 100 parts by weight of an ionomer, and an outer diameter of 42.
A 7-mm two-piece solid golf ball was produced.

The ball weight, coefficient of restitution, and impact force of the obtained golf ball were measured, and the feeling was evaluated by five players actually hitting with a No. 1 wood club. The results are shown in Tables 2 to 4 . The methods for measuring the coefficient of restitution and the impact force and the evaluation criteria for feeling are as follows.

Measurement method of coefficient of restitution: A stainless steel cylinder weighing 198 g was struck out with an air gun at an initial velocity of 45 m / s, and collided with a ball placed in front of it. Then, the coefficient of restitution is calculated from the speed and weight.

Measurement method of impact force: A Wood No. 1 club having an accelerometer attached to the back of the club was attached to a swing robot manufactured by True Temper, and a head speed was set to 45.
When 20 balls are hit at m / s in accordance with the flight distance test of the USGA, the acceleration at the time of hitting is obtained. The impact force is calculated from the acceleration, the ball weight, and the head weight thus obtained. And in the display,
It is indicated by an index with the golf ball of Example 3 being 100.

Feeling evaluation standard HH: The ball is too hard to hit. H: Hard. AH: Slightly hard, but within a good range. A: Good. AS: Slightly soft, but within a good range. S: Soft. SS: Too soft.

Table 2 shows the composition of the rubber composition for the core of Examples 1-4 and Comparative Examples 1-2, the ball weight, restitution coefficient, impact strength and feeling of the obtained golf balls. Shows those for Examples 5 to 8 and Comparative Examples 3 to 4, and Table 4 shows those for Example 9 and Comparative Examples 5 to 7. In these tables, an arrow (←) indicates that the value is the same as the value on the left.

In Tables 2 and 4, regarding the vulcanized rubber powder, the values in parentheses indicate the average particle size of the used vulcanized rubber powder after vulcanization molding. Regarding Table 3, since it cannot be indicated in the table due to space limitations, it is shown after Table 3 in comparison with the average particle size before compounding, but after vulcanization molding of the vulcanized rubber powder. The average particle size of the above-mentioned vulcanized rubber powder is blended in an inner core matrix composition, an inner core is produced with the obtained rubber composition, and an outer skin is coated thereon to produce a golf ball, and the obtained golf ball is halved. And the particle size of the vulcanized rubber powder in the cross section is measured in the same manner as the particle size of the vulcanized rubber powder before compounding.

The reason why the average particle size of the vulcanized rubber powder after the vulcanization molding is slightly smaller than the average particle size before the compounding is that the vulcanized rubber powder is crushed during vulcanization molding and that the maximum cross section of the vulcanized rubber powder is not necessarily observed. It is considered that this is not necessarily the case.

[0051]

[Table 2]

[0052]

[Table 3]

Comparison of average particle diameter of vulcanized rubber powder Composition Before compounding After vulcanization A 0.47 mm 0.41 mm B 0.08 mm 0.08 mm B 0.78 mm 0.72 mm B 1.02 mm 0.92 mm C 0.50 mm 0.45 mm D 0.52 mm 0.46 mm

[0054]

[Table 4]

As is clear from the results of Examples 1 to 4 shown in Table 2, the vulcanized rubber powder contained 35 to 200 parts by weight of the vulcanized rubber powder in a range of 35 to 200 parts by weight with respect to 100 parts by weight of the rubber contained in the inner core matrix. , High repulsion performance) and good feeling.

On the other hand, Comparative Example 1 in which the blended amount of the vulcanized rubber powder was small had a large impact force at the time of hitting, resulting in a poor feeling, and Comparative Example 2 in which the blended amount of the vulcanized rubber powder was large had a coefficient of restitution. Feeling was low and too soft.

Further, as is clear from the results shown in Table 3, Examples 5 to 8 in which the average particle size of the vulcanized rubber powder was 0.8 mm or less had a large coefficient of restitution and a good feeling. .

On the other hand, in Comparative Example 4 in which the average particle size of the vulcanized rubber powder was as large as 1.02 mm, the vulcanized rubber powder had a small coefficient of restitution and a large amount of the α, β-unsaturated fatty acid metal salt. In Comparative Example 3 using (Composition: D), the impact force at the time of hitting the ball was large and the feeling was poor.

As is clear from the results shown in Table 4, Example 9 in which the amount of zinc acrylate in the inner core matrix was 35 parts by weight had a high coefficient of restitution and a slightly soft feeling but in a good range. However, in Comparative Example 5 in which the amount of zinc acrylate was 28 parts by weight, the coefficient of restitution was small, and the feeling was too soft, which was not preferable.

In Comparative Examples 6 and 7 in which the vulcanized rubber powder was not blended, the impact force was large depending on the amount of zinc acrylate in each of the inner matrix matrices, or the ball was too hard to hit. Had the problem of.

Since the particle size of the vulcanized rubber powder after vulcanization molding is slightly smaller than the particle size before compounding, considering the vulcanized rubber powder after vulcanization molding, the average particle size is 0.75 mm.
Or less and preferably 0.01 mm or more.

In the above embodiment, the outer periphery of the inner core is covered with the outer shell composed mainly of resin. However, the golf ball of the present invention may have the outer skin covering the inner core with only the paint layer. .

[0063]

As described above, according to the present invention, a golf ball having high repulsion performance and good feeling can be provided.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a vulcanized rubber powder in order to explain a method for measuring a particle size of a vulcanized rubber powder in the present invention.

[Explanation of symbols]

 1 Vulcanized rubber powder

Claims (2)

(57) [Claims] 1. α, relative to 100 parts by weight of diene rubber
In an inner core matrix compound containing 35 parts by weight or more of β-unsaturated fatty acid metal salt, 25 parts by weight or less of α, β-unsaturated fatty acid metal salt is contained based on 100 parts by weight of diene rubber, and the average particle size before compounding Is 0.8 mm or less vulcanized rubber powder, 35 to 100 parts by weight of rubber in the inner core matrix compounding
A golf ball comprising an inner core made of a vulcanized molded product of a rubber composition mixed with 200 parts by weight. 2. The golf ball according to claim 1, wherein the average particle size of the vulcanized rubber powder after vulcanization molding of the rubber composition for the inner core is 0.75 mm or less.