JP3505243B2 - 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 having improved resilience and durability.

[0002]

2. Description of the Related Art Generally, a solid golf ball includes a rubber-made portion of a golf ball.
Included are the body portion of a one-piece golf ball, the core of a two-piece or three-piece solid golf ball, and the solid center of a wound golf ball. Of these, the rubber quality of the solid golf ball is mostly a base rubber such as high-cis polybutadiene, a co-crosslinking agent consisting of a metal salt of α, β unsaturated carboxylic acid, a metal oxide,
It is composed of a high-hardness and high-elasticity rubber obtained by crosslinking a compounding system composed of an organic peroxide (JP-A-49-48423). Such compounded rubber is also applied as a solid center of a wound golf ball (Japanese Patent Laid-Open No. 60-725).
73 publication). As such, the rubbery portion itself is of fairly good performance.

However, in recent years, particularly for solid golf balls, there has been a strong demand for golf balls having a better shot feeling. Therefore, it is common to make such a rubber portion softer than before. Such softening naturally has a limit in the conventional rubber material, resulting in a situation where the resulting golf ball lacks in resilience and durability. In order to improve this point, various investigations have been conducted on the amount of co-crosslinking agent, the amount of peroxide, the vulcanization temperature, etc., but satisfactory results have not yet been obtained, and the repulsion of the rubber portion of the golf ball The current situation is that drastic improvements in durability are strongly desired.

[0004]

As described above, in a golf ball having a rubber-like portion obtained by crosslinking a composition containing a base rubber, a co-crosslinking agent, a metal oxide and an organic peroxide, its rebound and durability Is desired. Therefore,
An object of the present invention is to provide a golf ball having a rubbery portion which is excellent in resilience and durability.

[0005]

In order to solve the above problems, the inventors of the present invention have made intensive studies by paying particular attention to the base rubber among the materials constituting the rubber portion of the golf ball, and as a result, Using high-cis polybutadiene containing a carboxyl group as an essential component of this base rubber, this base rubber, α,
It was found that a golf ball having a rubbery portion obtained by crosslinking a rubber composition containing a β-unsaturated carboxylic acid metal salt, a metal oxide and an organic peroxide has excellent repulsion and durability. The invention was completed.

Namely, the present invention is at least in part, in the golf ball composed of rubber, the rubber portion is cis 1, 4 bonds of 40% or more of high-cis polybutadiene Jie
A base rubber containing a carboxyl group-containing high cis polybutadiene formed by adding maleic anhydride to a vinyl ester as an essential component, a rubber composition containing a metal salt of an α, β unsaturated carboxylic acid, a metal oxide and an organic peroxide. Provided is a golf ball obtained by crosslinking an article.

In the present invention, the rubber portion having the above-mentioned specific structure usually constitutes a core in a two-piece solid golf ball, and constitutes an inner core or an outer core or both an inner core and an outer core in a three-piece solid golf ball. In the one-piece solid golf ball, the main body portion is formed, and in the thread wound golf ball, the center portion is formed.

In the present invention, since the carboxyl group of the carboxyl group-containing high-cis polybutadiene, which is an essential component of the base rubber, has the ability to form a metal salt, it interacts with the metal oxide during vulcanization to give a general high-cis content. It is possible to provide a crosslinked body having higher hardness and higher strength as compared with the case of using polybutadiene. Therefore, it is possible to obtain the same hardness with a smaller amount of the co-crosslinking agent, that is, it is possible to increase the fraction of the high-cis polybutadiene having good repulsion, so that high repulsion is also achieved. Conceivable. Hereinafter, the constitution of the present invention will be described in more detail.

The base rubber of the present invention contains a carboxyl group-containing high cis polybutadiene as an essential component, and the base polybutadiene has at least 40 cis 1,4 bonds.
%, Preferably 80% or more, it is desirable from the viewpoint of impact resilience. Usually, cis min 96
% Of high cis polybutadiene is commercially available, for example, BR-11 and BR-18 of Japan Synthetic Rubber, BR-200 and BR-1502 of Ube Industries, and they can be preferably used.

The carboxyl group-containing high cis polybutadiene of the present invention can be obtained by introducing a carboxyl group into the above polybutadiene by an addition reaction or the like. The introduction of such a carboxyl group is not particularly limited, for example,
This can be easily achieved by using a known technique as shown below. Further, the reaction can be carried out in solution or in solid phase.

Examples of such a carboxyl group-introducing reaction include addition reaction of maleic anhydride by heat or peroxide (Japanese Patent Publication No. 6-4751), addition reaction of thioglycolic acid in the presence of peroxide ( Rubber Chemistry and
Technology (Rubber Chemistry and Technology) No. 30
Vol., 1347 (1957)), 4-carboxy-phenyl-1,2,4-
Method using triazoline-3,5-dione (JP-A-48-8647)
7), a method using 4-carboxybenzhydroxamyl chloride (Journal of Japan Rubber Association, Vol. 43, No. 5, 36)
3 (1970)) and the like, and by modifying under the conditions described therein, a high cis polybutadiene having a carboxyl group can be obtained. The amount of the modifier used in this introduction reaction is not particularly limited, but is usually rubber 100.
It is within the range of 0.05 to 20 parts by weight and 0.2 to 10 parts by weight per part by weight.

The base rubber of the rubber composition includes the above-mentioned high-cis polybutadiene having a carboxyl group, general unmodified polybutadiene rubber, and styrene-butadiene rubber (SB
R), natural rubber, synthetic polyisobrene, ethylene-propylene-diene rubber (EPDM) and the like can be appropriately mixed and used, but 50% by weight or more of the base rubber is the above-mentioned carboxyl group-containing high cis polybutadiene. preferable.

The co-crosslinking agent blended in the rubber composition is α,
It is preferably a monovalent or divalent metal salt of β-unsaturated carboxylic acid, and specific examples thereof include zinc diacrylate, basic zinc methacrylate and zinc dimethacrylate. These α, β-unsaturated carboxylic acid metal salts can be used in a rubber composition in which a metal oxide such as zinc oxide (zinc white) is previously kneaded, in addition to the usual method of mixing a base rubber or the like as it is. Α, such as acrylic acid and methacrylic acid
A β-unsaturated carboxylic acid was added and kneaded, and the α, β-unsaturated carboxylic acid and the metal oxide were reacted in the rubber composition to obtain a metal salt of the α, β-unsaturated carboxylic acid. May be. Further, when a metal salt of α, β unsaturated carboxylic acid coated or mixed with a metal salt of a higher fatty acid described in JP-B-4-51190 is used as a co-crosslinking agent, further excellent physical properties can be obtained, and therefore it is particularly preferable. Can be used.

The blending amount of the above-mentioned co-crosslinking agent is not particularly limited, but it is usually preferably 10 to 70 parts by weight with respect to 100 parts by weight of the base rubber. If the blending amount of the co-crosslinking agent is less than the above range, the crosslinking will be insufficient, and as a result, the resilience performance will be reduced, the flight distance will be reduced, and the durability will be poor. On the other hand, if the blending amount of the co-crosslinking agent is larger than the above range, the compression becomes too large and the shot feeling becomes poor.

In the present invention, the rubber composition constituting the rubbery portion contains metal oxides and peroxides as essential components in addition to the co-crosslinking agent. Among them, the metal oxide acts as a cross-linking agent, and the heat applied to the rubber composition with the carboxyl group-containing high-cis polybutadiene can cause a metal ion cross-linking interaction. It can give strong properties to the rubbery part. Examples of such metal oxides include zinc oxide (zinc white), magnesium oxide, calcium oxide and the like. Among them, zinc oxide is particularly excellent and preferable.

Next, the peroxides act as an initiator for the crosslinking of the rubber and the co-crosslinking agent, graft polymerization and the like.
Suitable specific examples of the peroxides include dicumyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, 2,
Examples thereof include 5-dimethylhexane-2,5-dihydroperoxide.

The blending amount of the peroxides is 100
0.2 to 5 parts by weight is preferable with respect to parts by weight. If the amount of the peroxide compounded is less than the above range, crosslinking or the like cannot be sufficiently advanced, and as a result, the resilience performance is lowered, the flight distance is shortened, and the durability is deteriorated. On the other hand, if the blending amount of the peroxides is more than the above range, overcuring causes brittleness, resulting in poor durability.

The rubber composition may further contain, if necessary.
Fillers such as barium sulfate, antioxidants, chain transfer agents,
Additives such as zinc stearate, and metal hydroxides, carbonates, acetates, etc., such as basic zinc carbonate, zinc acetate, etc., in order to promote the interaction with the carboxyl groups of the carboxyl group-containing high-cis polybutadiene. You may mix | blend.

The formation of the rubbery part from this composition is
A general rubber vulcanizing method, for example, a normal rubber vulcanizer, for example, a hydraulic or hydraulic press, a predetermined mold is attached to a rubber injection, and the rubber composition is filled in the mold,
It is performed by heating.

A typical example of a golf ball having a rubber portion to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a one-piece solid golf ball. In FIG. 1, 1 is a main body portion and 1a is a dimple. In this one-piece solid golf ball, a rubber portion (that is, a base rubber containing a carboxyl group-containing high A rubber-like portion formed of a crosslinked product of a rubber composition containing cis-polybutadiene constitutes the main body portion 1.

FIG. 2 is a sectional view showing a two-piece solid golf ball. In FIG. 2, 11 is a core and 12 is a cover, and the cover 12 covers the core 11. And 12a is a dimple. In this two-piece solid golf ball, the rubber-like portion (that is, the rubber-like portion formed of the crosslinked product of the rubber composition containing the carboxyl group-containing high cis polybutadiene in the base rubber) constitutes the core 11.

FIG. 3 is a sectional view showing a three-piece solid golf ball. In FIG. 3, 21 is a core, 22 is an outer layer core, 23 is a cover, and 23a is a dimple.
In this three-piece solid golf ball, the outer core 22 is formed outside the inner core 21, and the inner core 21 and the outer core 22 constitute a so-called solid core, and the cover 23 is the outer core 22 of the solid core.
The top is covered. In the three-piece solid golf ball, the rubber-like portion (that is, the rubber-like portion formed of the crosslinked product of the rubber composition containing the carboxyl group-containing high cis polybutadiene in the base rubber) has the inner core 21 or the outer core 22. Alternatively, both the inner core 21 and the outer core 22 are configured.

FIG. 4 is a sectional view showing a thread-wound golf ball. In FIG. 4, 31 is a solid center, 32 is a thread rubber layer, 33 is a cover, and 33a is a dimple. In this thread-wound golf ball, the thread rubber layer 32 is formed by stretching and winding the thread rubber on the outside of the solid center 31, and the solid center 31 and the thread rubber layer 32 are formed.
And a so-called thread winding thread winding core, and the cover 33 covers the thread rubber layer 32. In this thread-wound golf ball, the rubber-like portion (that is, the rubber-like portion formed of the crosslinked body of the rubber composition containing the carboxyl group-containing high cis polybutadiene in the base rubber) constitutes the solid center 31.

The one-piece solid golf ball shown in FIG. 1 and the two-piece solid golf ball shown in FIG.
The three-piece solid golf ball shown in FIG. 3 and the thread-wound golf ball shown in FIG.
a, 23a, and 33a are provided on the outer peripheral portion of the solid golf ball in an appropriate number and shape according to need or desired characteristics. In the one-piece solid golf ball shown in FIG. It is formed on the outer peripheral portion, and is formed on the outer peripheral portions of the covers 12, 23 and 33 in FIGS.
Further, these golf balls are provided with paint or markings on the surface of the balls as needed.

Next, the outline of a typical method for producing the golf ball of the present invention will be described. First, the body portion of the one-piece solid golf ball, the core of the two-piece solid golf ball, the inner layer core of the three-piece solid golf ball, and the solid center of the thread-wound golf ball are composed of a base rubber containing a carboxyl group-containing polybutadiene, etc., respectively. The product is put in a predetermined mold and is cross-linked and molded by pressing. The crosslinking conditions are preferably a temperature of 130 to 180 ° C. and a time of 10 to 50 minutes. The temperature during the cross-linking molding is not necessarily constant, and the temperature may be changed in two or more steps.

In a three-piece solid golf ball,
A sheet-shaped product of the rubber composition for an outer layer core is attached to the outside of the inner layer core obtained as described above and crosslinked by pressing to form a solid core having a two-layer structure. However, in this case, the method is not limited to this method, and for example, a method of molding a half shell and pasting it or a method of molding by injection molding can be adopted. Also, in wound golf balls,
A highly stretched rubber thread is wound around the solid center obtained as described above to form a wound core.

The cover of the two-piece solid golf ball, the three-piece solid golf ball, and the thread-wound golf ball is composed of a resin component containing an ionomer resin as a main component, and if necessary, an inorganic white pigment such as titanium dioxide and an additive such as a light stabilizer. It is formed by coating the above-mentioned core with a cover composition in which the above is properly blended. For coating, an injection molding method is usually adopted, but the method is not limited to this.

Desired dimples are formed, if necessary, at the time of molding the main body of the one-piece solid golf ball, and at the time of molding the cover of the two-piece solid golf ball, the three-piece solid golf ball and the thread wound golf ball. If necessary, a paint or marking is applied to the subsequent solid golf ball to finish the ball.

In the three-piece solid golf ball, the outer core may be made of the rubber composition of the present invention composed of a base rubber containing carboxyl group-containing polybutadiene, instead of the inner core described above. Alternatively, both the inner core and the outer core may be made of the rubber composition of the present invention comprising a base rubber containing a carboxyl group-containing polybutadiene.

[0030]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to those examples. (Examples 1 to 6, Comparative Examples 1 to 3) Various polybutadiene rubbers were roll-kneaded with zinc diacrylate, zinc oxide, dicumyl peroxide and an antioxidant, and the resulting rubber compositions were heated at 150 ° C for 30 minutes. It was pressure-crosslinked to obtain a core having a diameter of 38.5 mm. Table 1 shows the types of polybutadiene rubber used in Examples and Comparative Examples and the content of its blending.

[0031]

[Table 1]

(* 1) High cis polybutadiene with maleic anhydride added as a carboxyl group. Using BR-11 made by Japan Synthetic Rubber as high-cis polybutadiene,
Maleic anhydride was added and introduced by the method described below. BR-11 was dissolved in xylene, and in a nitrogen stream,
BR-11 maleic anhydride and hydroquinone / maleic anhydride
/Hydroquinone=100/7.0/2.0 parts by weight,
Benzoyl peroxide was added at 0.5% by weight of BR-11.
The mixture was reacted with stirring at 0 ° C. for 2 hours. The reaction solution was poured into a large amount of acetone, the precipitate was filtered and dried. (* 2) High-cis polybutadiene with maleic anhydride added as a carboxyl group. It was produced by the same method as (* 1) except that BR-150L manufactured by Ube Industries was used as the high-cis polybutadiene. (* 3) A high-cis polybutadiene having a carboxyl group introduced by the following method using 4-carboxybenzhydroxal chloride. BR-11 made by Nippon Synthetic Rubber is dissolved in a mixed solvent of toluene and methanol, 4-carboxybenzhydroxal chloride is dissolved in this solution, triethyleneamine is added thereto, and the mixture is reacted overnight at room temperature, and hydrochloric acid is added. After acidification, methanol is added to precipitate the polymer. This was purified by reprecipitation with toluene / methanol and dried to obtain a high-cis polybutadiene having a carboxyl group introduced. Here, BR-11 / 4-carboxybenzhydroxal chloride / triethyleneamine = 100/5/6 weight ratio was added. (* 4) A high-cis polybutadiene having a carboxyl group introduced by the following method using 4- (p-carboxyphenyl) -1,2,4-triazolidine-3,5-dione. Add BR-11 to the Brabender type plastomill and knead at rotor 50 rpm. 4- (p-carboxyphenyl) -1,2,4-triazolidine-3, dissolved in THF (tetrahydrofuran),
5-dione was added, and the mixture was kneaded at 130 ° C. for reaction. The end point of the reaction is detected by the increase of the torque value. Where BR-1
1 / 4- (p-Carboxyphenyl) -1,2,4-triazolidine-3,
5-dione was added at a weight ratio of 100 / 7.4. (* 5) Trade name of high-cis polybutadiene made by Japan Synthetic Rubber. M _{L1 + 4} (100 ° C.) = 43, cis content = about 96%. (* 6) Ube Industries' high-cis polybutadiene product name. M _{L1 + 4} (100 ° C.) = About 40, cis content = about 96%. (* 7) Zinc diacrylate containing 10% by weight of zinc stearate. (* 8) Trade name of 2,2′-methylenebis (4-ethyl-6-t-butyl-phenol), an antioxidant manufactured by Yoshitomi Pharmaceutical Co., Ltd.

Next, the core obtained as described above is coated with a composition for a cover comprising a mixture of 100 parts by weight of an ionomer resin and 2 parts by weight of titanium dioxide by an injection molding method to form a cover. A two-piece solid golf ball having a diameter of 42.7 mm was produced. The ionomer resin used is
It is a mixture of Himilan # 1706 (trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd.) and Himilan # 1605 (trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd.) in a weight ratio of 50:50.

With respect to the two-piece solid golf ball thus obtained, its weight and compression
(PGA display), ball initial velocity, flight distance (carry), and hammering durability were measured. The results are shown in Table 2.

[0035]

[Table 2]

As is clear from the results shown in Table 2, the golf balls of Examples 1 to 6 of the present invention have a ball initial velocity higher than that of the golf balls of Comparative Examples 1 to 3 which are composed of cores using ordinary polybutadiene. Large, that is, good repulsion, increased flight distance, and excellent durability.

(Examples 7 to 10, Comparative Examples 4 to 6) The compounding materials shown in Table 3 were kneaded with a kneader and a roll to prepare a rubber composition, and the obtained rubber composition was filled in a mold. , 17
By pressure crosslinking for 18 minutes at 4 ° C., a one-piece solid golf ball composed of an integrally molded body having an outer diameter of 42.7 mm was produced.

[0038]

[Table 3]

With respect to the obtained one-piece solid golf ball, the weight, compression (indicated by PGA), ball initial velocity, flight distance (carry) and hammering durability were measured as in the case of the two-piece solid golf ball. The results are shown in Table 4.

[0040]

[Table 4]

As shown in Table 5, also in these one-piece solid golf balls, Examples 7 to 7 of the present invention were performed.
The golf ball of No. 10 had a higher initial velocity of the ball, that is, good repulsion, increased flight distance, and excellent hammering durability as compared with the golf balls of Comparative Examples 4 to 6.

The methods for measuring the ball initial velocity, flight distance and hammering durability are as follows. (Initial speed of the ball) Attach the No. 1 wood club to the swing robot manufactured by Trutemper, and head speed the ball.
Hit at 45 m / sec and measure the ball's initial velocity at that time. (Flying distance (carry)) Distance to the drop point of the ball when the No. 1 wood club is attached to the swing robot made by Trutemper and the ball is hit at a head speed of 45 m / sec.
Measure (yard). (Hummering durability) The ball was repeatedly collided with the collision plate at a speed of 45 m / sec, the number of collisions until the ball was broken was examined, and the number of times until the ball of Comparative Example 1 was broken was 100.
It shows with the index.

[0043]

According to the present invention, there is provided a golf ball having a rubber portion having excellent resilience and durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a one-piece solid golf ball.

FIG. 2 is a cross-sectional view of a two-piece solid golf ball.

FIG. 3 is a cross-sectional view of a three-piece solid golf ball.

FIG. 4 is a cross-sectional view of a thread-wound golf ball.

[Explanation of symbols]

1… Main body 1a, 12a, 23a, 33a ... Dimples 11… Core 12, 23, 33… Cover 21… Inner core 22… Outer core 31… Solid Center 32… Thread rubber layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI C08L 13/00 C08L 13/00 (58) Fields investigated (Int.Cl. ⁷ , DB name) A63B 37/00

Claims (4)

(57) [Claims] 1. A golf ball, at least a portion of which is made of rubber, wherein the rubber portion is cis 1 , 4
High-cis polybutadiene with 40% or more bonds to anhydrous male
Crosslinking a base rubber containing a high-cis polybutadiene having a carboxyl group as an essential component formed by adding an acid, a rubber composition containing a metal salt of an α, β unsaturated carboxylic acid, a metal oxide and an organic peroxide. A golf ball which is obtained by 2. The golf ball according to claim 1, wherein the proportion of the high-cis polybutadiene having a carboxyl group in the base rubber is 50% by weight or more. 3. The α, β unsaturated carboxylic acid metal salt is zinc diacrylate or zinc dimethacrylate or basic zinc methacrylate or a mixture thereof, and the metal oxide is zinc white. Golf ball. 4. (a) cis 1, 4 bonds of 40% or more of high
Add maleic anhydride to cis-polybutadiene
Forming a high cis polybutadiene containing a xyl group,
And (b) the carboxyl group-containing high-cis polybutadiene
Of base rubber containing α and β unsaturated carboxylic acids
Rubber composition containing metal salt, metal oxide and organic peroxide
Including the step of cross-linking objects to form rubbery parts,
Both are made of golf balls, some of which are made of rubber.
Build method.