JP2001149506A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball having good workability, high repulsiveness, an improved initial velocity and an increased distance. SOLUTION: This golf ball consists of a thermal molding of a rubber composition formed by using a base material rubber containing 10 to 100 mass % polybutadiene which is a polybutadiene containing >=90% cis-1,4 bond and the Mooney viscosity of which is <50 and in which the ratio Mw/Mn of the weight average molecular weight Mw (×104) to the number average molecular weight Mn (×104) is 2.0 to 4.0 and which is synthesized by using a rare earth element catalyst as an essential component. The rubber composition is compounded with an inorganic filler at <=20 mass parts per 100 mass part base material rubber and is used as the constitution element of the golf ball.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD [0001] The present invention has good processability,
In addition, the present invention relates to a golf ball using a rubber composition giving high resilience.

[0002]

2. Description of the Related Art Golf balls are roughly classified into solid golf balls and thread-wound golf balls. BACKGROUND ART A rubber composition is used as a material for an intermediate layer and a cover of a solid core, and in some cases, a multiple solid golf ball of three pieces or more. In a thread wound golf ball, a rubber composition is used for materials such as a solid center and thread rubber.

[0003] The rubber composition used in such golf balls is generally desired to have high resilience.
Conventionally, in the development of a high resilience rubber composition, as a base rubber constituting a main component of the rubber composition, a material having a high Mooney viscosity and a high average molecular weight has been regarded as an important index of high resilience. .

For example, a conventionally proposed rubber composition for golf balls has been synthesized using a nickel catalyst and / or a cobalt catalyst as polybutadiene.
And Mooney viscosity [ML _{1 + 4} (100 ° C)] 70-1
A polybutadiene having a Mooney viscosity [ML _{1 + 4} (100 ° C.)] of less than 50 parts by mass or a nickel-based catalyst, /
Alternatively, 20 to 80 parts by mass of a polybutadiene synthesized using a cobalt catalyst and having a Mooney viscosity [ML _{1 + 4} (100 ° C.)] of 20 to 50 is blended to make the total amount of polybutadiene 100 parts by mass ( 6-801
No. 23), 5 to 50% by mass of an ultrahigh molecular weight polybutadiene rubber having at least 80% or more of cis-1,4 bonds and having a number average molecular weight of more than 40 × 10 ⁴ , and cis-1,4
Having at least 80% or more bonds and a number average molecular weight of 40 ×
A solid polybutadiene (JP-A-3-151985) obtained from a solution mixture of about 95 to 50% by mass of a polybutadiene rubber of less than 10 ⁴ , a lanthanum-based rare earth element compound-based catalyst, a nickel-based catalyst or a cobalt-based catalyst At least 4 cis-1,4 bonds obtained using
0% or more, Mooney viscosity [ML _{1 + 4} (100
C) is 50 to 70% or a mixture of polybutadienes having different catalysts of the above polybutadiene, and 60 to 95% by mass,
A rubber component containing a mixture of 5 to 40% by mass of polyisoprene containing at least 90% of cis-1,4 bonds and having a Mooney viscosity [ML _{1 + 4} (100 ° C.)] of 70 to 90 (Japanese Unexamined Patent Application Publication No. No. 6-190083), the base rubber has a Mooney viscosity [ML _{1 + 4} (100 ° C.)] of 45 to 90, and a ratio (Mw / Mn) between the number average molecular weight (Mn) and the weight average molecular weight (Mw). 0 to 8.0, and at least 40% by mass or more of polybutadiene rubber having at least 80% or more of cis-1,4 bond (Japanese Patent No. 2644)
No. 226).

[0005] Here, the processability of the rubber composition is an important problem that cannot be ignored by golf ball manufacturers. In order to improve the processing performance of the rubber composition, it was said that a wider molecular weight distribution was better and a lower Mooney viscosity was better. Therefore, as described above, a blend of polybutadiene having high Mooney viscosity and polyisoprene may be blended (Japanese Patent Laid-Open No. 6-1900).
No. 83), using polybutadiene having a high Mooney viscosity and a wide molecular weight distribution (Japanese Patent No. 2644226), blending a high molecular weight polybutadiene with a low molecular weight polybutadiene (Japanese Patent Application Laid-Open No. 3-151985), Blend Mooney viscosity polybutadiene with high Mooney viscosity polybutadiene
No. 80123), thereby achieving both resilience and workability.

[0006] However, a material having higher resilience and excellent workability is desired.

The present invention has been made in view of the above circumstances. By using a rubber composition which is excellent in processability and gives high resilience, the productivity is good, the initial speed is large, and the flight distance is increased. It is intended to provide a golf ball.

[0008]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, as described above, when developing a highly resilient rubber composition, Viscosity and high average molecular weight had been used, but found that Mooney viscosity was not always high and average molecular weight was not necessarily high enough to give satisfactory results. As a result of repeated studies on compatibility, it was found that the cis-1,4 bond was 90% or more and the molecular weight distribution (weight average molecular weight /
When the number average molecular weight is 2.0 to 4.0 and the Mooney viscosity (10
Addition of a small amount of an inorganic filler to a base rubber containing polybutadiene obtained by using a rare earth element-based catalyst having an ML _{1 + 4} ) of less than 50 (0 ° C., ML _{1 + 4} ) provides both good workability and resilience. I found that. That is, as a method of improving the processability of the rubber composition, there is a method of compounding a relatively large amount of a filler. In such a case, 100 parts of a base rubber (parts by
The same applies to the following), by adding a large amount of an inorganic filler, for example, 50 parts or more, the shape at the time of rubber extrusion can be stabilized, but on the other hand, the rubber fraction in the rubber composition decreases, Although it was inevitable that the resilience was reduced, the polybutadiene was used as a base rubber component, and 20 parts or less, particularly 10 to 20 parts of an inorganic filler was compounded with respect to 100 parts of the base rubber. Thereby, even if the molecular weight distribution of polybutadiene is as low as 2.0 to 4.0, the kneading of the polybutadiene has a very good winding property on a roll, and the state of rubber when processed into a sheet, etc. The rubber composition has high resilience even if the Mooney viscosity is low, and the inorganic filler is added to the base rubber containing the polybutadiene. Mix a small amount By using the rubber composition, the initial velocity was increased, and it was found that a flight distance could be increased, that is, a rubber composition having both processability and resilience was obtained, and the present invention was accomplished. Things.

Accordingly, the present invention provides a method for preparing a cis-1,4 bond at 9
A polybutadiene containing 0% or more, having a Mooney viscosity of less than 50 and a ratio Mw / Mn of the weight average molecular weight Mw (× 10 ⁴ ) to the number average molecular weight Mn (× 10 ⁴ ) of 2.
0 to 4.0, and a base rubber containing 10 to 100% by mass of polybutadiene synthesized using a rare earth element-based catalyst, and 20 parts or less of an inorganic filler based on 100 parts of the base rubber. Provided is a golf ball characterized by comprising, as a component, a heat molded product of a compounded rubber composition.

Hereinafter, the present invention will be described in more detail.
The rubber composition used in the golf ball of the present invention contains 90% or more of cis-1,4 bonds as a rubber base material and has a Mooney viscosity (100 ° C., ML _{1 + 4} ) of less than 50, preferably 45. In the following, a polybutadiene whose lower limit is preferably 20 is used. It is not preferable that the Mooney viscosity is 50 or more from the viewpoint of processability. This polybutadiene has a weight average molecular weight of Mw (× 1
0 ⁴ ), and when the number average molecular weight is Mn (× 10 ⁴ ), the molecular weight distribution Mw / Mn is 2.0 to 4.0, preferably 2.
It is necessary to be 3 to 3.7, more preferably 2.5 to 3.5. If Mw / Mn is smaller than 2.0, processability is poor, and if Mw / Mn is larger than 4.0, resilience is reduced.

In this case, the polybutadiene has a viscosity η of a 5% toluene solution at 25 ° C. from the viewpoint of resilience.
(MPa · s) is 100 or more, especially 150 or more,
More preferably, it is 200 to 600.
Similarly, from the viewpoint of resilience, it is preferable that the viscosity η and the Mw satisfy the relationship of η> 5 × Mw-150.

The Mw is 30 to 80 (× 10 ⁴ ).
In the range.

As the above-mentioned polybutadiene, commercially available products can be used, and among them, those formed using a rare earth element-based catalyst as a polymerization catalyst, and those formed using a neodymium-based catalyst are preferable.

Incidentally, polybutadiene is described in, for example,
A polymer modified by reacting with a terminal modifier after polymerization by the method described in -268132 or the like can be used.

In the base rubber of the present invention, the above polybutadiene can be used in a proportion of 10 to 100% by mass. In this case, the proportion can be selected according to where the rubber composition is used in the golf ball, etc., but the effect can be exhibited even if the polybutadiene is less than 50% by mass.

The rubber component other than the above-mentioned polybutadiene includes other polybutadienes, such as the polybutadiene described in the above-mentioned conventional example, other polybutadienes commonly used in golf balls, and polyisoprene.
Diene rubbers such as styrene butadiene rubber and natural rubber can be used.

The rubber composition of the present invention may further comprise, in addition to the above base rubber, zinc salts of unsaturated fatty acids such as zinc acrylate and zinc methacrylate, magnesium salts of unsaturated fatty acids, other metal salts, and triethanolpropane methacrylate. And the like, and a crosslinking agent such as an unsaturated fatty acid such as methacrylic acid for 100 parts of the base rubber.
It is contained in the range of 0 parts.

Further, an organic peroxide such as dicumyl peroxide is preferably used in an amount of 0.1 part per 100 parts of the base rubber.
It is contained in the range of 1 to 3 parts. Further, if necessary, a vulcanizing agent such as an organic sulfur compound such as pentachlorothiophenol zinc salt or diphenyl disulfide can be blended in an amount of 0.01 to 5 parts with respect to 100 parts of the base rubber.

Further, if necessary, an anti-aging agent such as 2,2-methylenebis (4-methyl-6-tert-butylphenol) and a filler such as zinc oxide, barium sulfate, calcium carbonate and the like for adjusting specific gravity. Can be blended. In this case, the compounding amount of the filler is, in the present invention,
20 parts or less, preferably 10 to 10 parts of base rubber
The amount is 20 parts, and if it is more than 20 parts, it is not preferable in terms of resilience.

The rubber composition is kneaded using a usual kneading machine, for example, a Banbury mixer, kneader, roll, or the like, and the obtained compound is formed into a desired shape by compression molding, injection molding, or the like. In this case, vulcanization can be performed at 130 to 180 ° C. for 10 to 60 minutes.

The golf ball of the present invention is a one-piece solid golf ball, a two-piece solid golf ball,
Multiple solid golf balls, three or more pieces,
Although it can be manufactured as a thread wound golf ball, the rubber composition according to the present invention can be used for one-piece golf balls, two-piece golf balls,
It can be used as the rubber material of the innermost layer solid core, outermost layer cover and intermediate layer formed between these cores and the cover of multiple solid golf balls of three pieces or more. Or one or more layers of cover material.

In this case, the configuration of the golf ball can be an ordinary configuration, for example, a known configuration such that the solid core has one or more layers and the cover has one or more layers. And can be formed to a diameter of not less than 42.67 mm and a weight of not more than 45.93 g according to the Rules of Golf.

[0023]

The golf ball of the present invention has excellent workability, high resilience, improved initial velocity and increased flight distance.

[0024]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

EXAMPLES / COMPARATIVE EXAMPLE I Using the polybutadiene (BR) shown in Table 1, the components shown in Table 2 were kneaded in a kneader, and then pressed at 155 ° C. for 25 minutes to form a diameter 3
An 8.5 mm solid core was made.

An ionomer resin (Himilan 16) colored and adjusted in specific gravity as a cover material is added to the solid core.
05, manufactured by DuPont-Mitsui Polychemicals Co., Ltd.), and covered with a cover by injection molding to have a diameter of 42.7 mm and a weight of 4
5.2 g of a two-piece solid golf ball was obtained.

Table 2 shows the measurement results of the hardness and initial velocity of the solid core, the flight distance of the solid golf ball, and the workability.

[0028]

[Table 1] Note that η (mPa · s) of BR (a) is 260.

[0029]

[Table 2] * 1: Anti-aging agent Nocrack NS-6 / Ouchi Shinko Chemical * 2: Core hardness Deflection of core under 980N load load The larger the value, the softer the core. * 3: Core initial speed Same type as the official agency USGA Measured with an initial speedometer Expressed as a difference based on the value of Comparative Example 2 * 4: Ball flying distance Comparative example of carry when a W # 1 club is attached to a robot machine and hit at a head speed of 45 m / s * 5: Processability Judged from the state of wrapping around a roll, the state of rubber processed into a sheet, and the state of dispersion of chemicals.

Example / Comparative Example II The components shown in Table 3 were kneaded in a kneader and then pressed at 155 ° C. for 25 minutes to produce an inner core having a diameter of 35.2 mm.

The inner layer was coated with an intermediate layer by injection molding using an ionomer resin (Himilan 1855, manufactured by DuPont-Mitsui Polychemicals Co., Ltd.) whose coloring and specific gravity had been adjusted to form a solid core having a diameter of 38.6 mm. ,
Further, the cover was covered by injection molding using an ionomer resin (Himilan 1605, manufactured by Du Pont-Mitsui Polychemicals Co., Ltd.) whose coloring and specific gravity were adjusted, and the diameter was 42.7 mm.
A three-piece solid golf ball weighing 45.2 g was obtained.

Table 3 shows the results of measuring the hardness and initial velocity of the solid core, the flight distance of the solid golf ball, and the workability.

[0033]

[Table 3] * 1: Anti-aging agent Nocrack NS-6 / Ouchi Shinko Chemical * 2: Core hardness Deflection of core under 980N load load The larger the value, the softer the core. * 3: Core initial speed Same type as the official agency USGA Measured with an initial speedometer Expressed as the difference based on the value of Comparative Example 5 * 4: Ball flying distance Comparative example of carry when a W # 1 club is attached to a robot machine and hit at a head speed of 45 m / s * 5: Processability Judged from the state of wrapping around a roll, the state of rubber processed into a sheet, and the state of dispersion of chemicals.

Claims (1)

[Claims] 1. A polybutadiene containing at least 90% of cis-1,4 bonds, having a Mooney viscosity of less than 50, a weight average molecular weight Mw (× 10 ⁴ ) and a number average molecular weight M
a base rubber containing 10 to 100% by mass of polybutadiene having a ratio Mw / Mn to n (× 10 ⁴ ) of 2.0 to 4.0, and synthesized using a rare earth element-based catalyst, 20 parts of the inorganic filler is added to 100 parts by mass of the base rubber.
A golf ball comprising, as a constituent, a heat-molded product of a rubber composition compounded in an amount of not more than part by mass.