JP7288924B2 - Method for manufacturing rubber products using gamma ray emitting powder as vulcanizing agent - Google Patents

Description

The present invention relates to a rubber product in which a gamma ray emitting powder having a predetermined radiation intensity is used as a vulcanizing agent for a rubber product to crosslink the rubber component, and after vulcanization, the gamma ray emitted from the product can be continuously used . The present invention relates to a manufacturing method and a grip manufactured using the same .

Conventionally, the vulcanization of rubber products generally refers to the thermal curing of rubber as vulcanization/crosslinking. It means that it becomes a mesh-like structure in which sulfur binds a part of the molecular chains. Through this chemical reaction, rubber acquires strong elasticity and stable heat resistance.
In general, the meaning of “crosslinking” is used in the same way as “vulcanization”, but molecular bonding using organic peroxides other than sulfur, metal oxides, organic amine compounds, etc. is called “crosslinking”. There are a wide variety of cross-linking methods for obtaining this rubber elasticity, and by creating cross-linked portions in the arrangement of network-like molecular bonds, a wide range of elastic materials can be created, from liquid-like soft substances to ebonite-like hard substances. be able to.
Generally, in golf balls, since the elastic core material is formed using a vulcanizing agent, the hardness inside the core is high on the outside and low on the center (Patent Document 1). On the other hand, it is characterized by being a rubber product or leather product that contains, as main raw materials, natural ore powder with far-infrared radiation characteristics and rubber raw material or leather raw material, and that it relates to a part that can come into contact with the human body. Golf equipment has been proposed (Patent Document 2). Focusing on zirconium ore containing radioactive elements, it has been proposed to knead fine powder of the zirconium ore into a rubber composition to provide a rubber product with medical effects by radium radiation (Patent Document 3). ).

JP-A-2000-80203 Japanese Patent Application Laid-Open No. 2001-252388 Japanese Unexamined Patent Application Publication No. 2007-209441

However, all rubber products use a cross-linking agent or a vulcanizing agent in addition to the filler to cross-link the rubber component, which complicates the structure of the rubber composition, but is insufficient. For example, in the case of a golf ball, a rubbery elastic material is used as the core. It was found that the nonuniformity affects the coefficient of restitution. On the other hand, conventional mixing of natural ore powder with far-infrared radiation characteristics does not radiate gamma rays, and the effect of imparting hormesis is insufficient. In addition, the zirconia ore powder has a small radiation dose, and for example, the actually used radiation dose of 0.12±0.003 μSv/h (equivalent to 1.1 mSv/y) cannot crosslink the rubber component.
Therefore, it is desired to manufacture a rubber product, such as a core ball, having a uniform hardness distribution. However, even if the vulcanizing agent is uniformly mixed and dispersed, it is difficult to uniformly heat the inside and outside. However, it has not been adopted because it is difficult to ensure safety against

In the manufacture of golf balls, an excipient such as zinc oxide is added to adjust the weight of the ball . When the radiation dose at the time of contact with the gamma ray measuring instrument is adjusted to 3 to 20 mSv/y (millisieverts per year), the weight of the ball can be adjusted, and at the same time, It has been found that the rubber component of the core can be evenly vulcanized with a desired hardness by combined use with an ordinary cross-linking agent to form a ball with a uniform hardness distribution. That is, by using a predetermined radium ore powder and adjusting the radiation dose of the radium wire within a predetermined range, the rubber component can be vulcanized, and the product rubber hardness and radium We have found that both the dose of radiation can be adjusted.
Accordingly, an object of the present invention is to provide a method for producing rubber products using a rubber composition which is vulcanized using radium ore powder alone or as a vulcanizing agent.

The present invention was made by paying attention to the fact that synthetic rubber such as silicone rubber, butadiene, and natural rubber can be crosslinked with gamma ray radiation powder. When 15 to 100 parts by weight of radium ore powder of sievert) and is vulcanizable, and can be used to provide gamma-radiative products such as golf ball uniform hardness cores and grips. The rubber composition of the present invention is a golf ball comprising a core and a cover surrounding the core, wherein the core contains 200 to 1000 becquerels of radium ore powder per gram per 100 parts by weight of synthetic rubber or natural rubber. 15 to 100 parts by weight of is mixed and vulcanized, and is made of a rubber material having a gamma ray radiation amount of at least 3 to 20 mSv/y when in contact with a gamma ray measuring instrument, and radium ore powder is used instead of ZnO as a filler. A gamma ray radiation rubber characterized by mixing, kneading and quenching to evenly crosslink the core rubber component, making the Shore C hardness almost uniform from the outside to the center of the core, and having a good coefficient of restitution. Applied to golf balls using the composition,
Secondly, a grip of a golf club, which is vulcanized by mixing 15 to 100 parts by weight of radium ore powder of 200 to 1000 becquerels per gram with 100 parts by weight of synthetic rubber or natural rubber. The grip is made of a rubber material with a gamma radiation dose of at least 3 to 20 mSv/y when in contact with a gamma ray measuring instrument, mixed with radium ore powder as a filler, kneaded with rubber, and quenched. In order to control the bending of the shaft, the grip tapers gradually from the end to the tip. At least the hardness of the tip of the grip is increased so that the grip force up to the tip of the grip can be easily transmitted to the shaft, and excessive bending of the shaft can be controlled. It is applied to a club grip using a gamma ray emitting rubber composition characterized by:

The present invention uses a radium ore powder that emits radiation gamma rays as a cross-linking agent, uniformly cross-links rubber products, and can provide rubber products that can continue to use radiation gamma rays even after cross-linking.

In particular, when it is used to manufacture a rubbery elastic core for a solid golf ball comprising a rubbery elastic core and a single- or multiple-layered resin cover covering the outer side of the elastic core, unique effects can be obtained. Demonstrate. That is, with 100 parts by weight of synthetic rubber or natural rubber, 15 to 100 parts by weight of radium ore powder of 0 to 1000 becquerel per gram is mixed to adjust the weight, and vulcanized as usual to obtain a uniform shear hardness. A solid golf ball is manufactured having an elastic core with a

In golf balls, ZnO is used as an excipient for weight adjustment, but if radium ore powder is used instead, it not only works as an excipient to adjust weight, but also functions as a vulcanizing agent. do. Considering the Becquerel value per gram of radium ore powder, it can be mixed in an amount of 15 to 100 parts by weight, preferably 25 to 50 parts by weight, with respect to 100 parts by weight of the rubber material, either alone or In combination with other vulcanizing agents, it is possible to produce a rubbery core with a desired hardness.
Synthetic rubber is usually used for the core material, and when a vulcanizing agent is added and quenched, the hardness gradually decreases from the outside to the inside. When 25% ZnO excipient and vulcanizing agent are added to the rubber material and kneaded, and the outer side is baked so that the C hardness is 80, the C hardness is about 55 to 65 near the center of the core. For example, 1) when radium ore powder is mixed into the rubber material of the core instead of ZnO, and the rubber is kneaded as usual and quenched as usual, gamma rays are emitted from the radium ore powder and the rubber component is crosslinked. It progresses evenly and can have the same hardness from the outside to the central part. By the way, the Shore C hardness was uniform from 65 to around 70 from the outside to the center of the core, and a better coefficient of restitution than before was maintained. When it was finished into a ball and measured (assuming the same cover material), 510 kg was required for the above-mentioned conventional core to deform by 10 mm, but the core containing radium powder required 440 kg for the same amount of deformation. . That is, in comparison with the core, the same coefficient of restitution was obtained with 15% weaker force, which is a good result for women and senior golfers with slow head speeds.
2) When the vulcanization method of the present invention was applied to golf grips, the following results were obtained. The grip gradually becomes thinner from the end of the grip, and becomes considerably thinner at the tip. As a result of being able to increase the hardness of the shaft and control the excessive bending of the shaft, it becomes easier to design a hardness that makes it easy to transfer the grip force up to the tip of the grip to the shaft. In addition, the gamma rays continuously emitted from the entire grip give a hormesis effect to the hand holding the grip, giving a good grip feeling.

1 is a table showing components and measurement results of radium ore powder used in the present invention. 1 is a cross-sectional view of a golf ball according to the present invention; FIG. 1 is a cross-sectional view of a club grip according to the present invention; FIG.

The present invention will be described in more detail below. In Embodiment 1, the golf ball obtained according to the present invention has an elastic core of rubbery uniform hardness, which can be manufactured using known synthetic rubbers and natural rubbers. This ball 10 is manufactured by forming an inner cover 12 and an outer cover 13 on a core 11, as shown in FIG. Embodiment 2 describes a grip product attached to a club shaft. The grip 20, as shown in FIG. 3, is constructed to increase the hardness of at least one-third, or the entirety, of the tip 22 of the grip body 21 to limit bending of the club shaft.

[Embodiment 1] The elastic core material of a golf ball can be formed from a rubber composition whose main component is, for example, a base rubber whose main component is polybutadiene, polyisoprene, natural rubber, or silicone rubber. Polybutadiene is particularly preferred for increasing the resilience. In this case, the polybutadiene is preferably 1,4-cis polybutadiene having a cis structure of at least 40%. If desired, natural rubber, polyisoprene, styrene-butadiene, or the like can be blended with the above-mentioned polybutadiene. preferably.

In the rubber composition, conventionally, in addition to the above-mentioned base rubber, known compounding components such as zinc methacrylate, zinc salts of unsaturated fatty acids such as zinc acrylate, magnesium salts, trimethylpropane methacrylate, etc. are used as cross-linking agents. Although an ester compound or the like is blended, in the present invention, radium ore powder is used in addition to or instead of this. Although the amount of the radium ore powder cross-linking agent to be blended depends on the amount of other cross-linking agents, it is usually 15 parts by weight or more and 100 parts by weight, particularly 25 parts by weight or more, with an upper limit of 50 parts by weight, per 100 parts by weight of the base rubber. parts by weight are preferred.

A vulcanizing agent such as dicumyl peroxide is usually blended in the rubber composition, and uniform vulcanization and vulcanization with a desired hardness can be achieved by using this together.

Zinc oxide, barium sulfate, and the like have conventionally been added to the rubber composition as antioxidants and fillers for adjusting specific gravity, but these fillers need not be added.

An example of a preferred embodiment of the rubber composition for elastic core is shown below.
[Example] Cis-1,4-polybutadiene 100 parts by weight Radium ore powder (500 becquerel/g) 15 to 50 parts by weight Zinc acrylate 15 to 40 parts by weight Barium sulfate 0 to 40 parts by weight Peroxide 0.1 to 5 .0 part by weight Vulcanization conditions: Knead at room temperature for 30 to 60 minutes, preferably vulcanize at 155°C ± 10°C for 5 to 20 minutes.
As the radium ore powder, boxwood radium ore powder having the performance shown in FIG. 1 was used.

[Comparative Example] 100 parts by weight of cis-1,4-polybutadiene,
5 to 40 parts by weight of zinc oxide,
15 to 40 parts by weight of zinc acrylate,
0 to 40 parts by weight of barium sulfate,
0.1 to 5.0 parts by weight of peroxide Vulcanization conditions: Vulcanization is preferably carried out at 155°C ± 10°C for 5 to 20 minutes.

The elastic core is produced by kneading the above core rubber composition with a conventional kneader (e.g., Banbury mixer, kneader, roll, etc.), and injection molding or compression molding the resulting compound using a core mold. It can be obtained by adopting. In this case, the vulcanization conditions of the rubber composition are not particularly limited, but usually quenching is performed at 155°C ± 10°C for 5 to 20 minutes.

The hardness of the elastic core is not particularly limited, but it can be determined by the amount of radium ore powder blended with respect to the rubber component in order to more reliably exhibit excellent performance for the inner and outer covers. Shore C hardness is adjusted around 60 to 70. Normally, the amount of deflection when a load of 980.7 N (100 kgf) is applied is usually adjusted to 3.0 mm or more, especially 3.2 mm or more, and the upper limit is 4.5 mm or less, especially 4.3 mm or less.

Examples of the inner cover material include polyester resins, polyester elastomers, ionomer resins, styrene elastomers, polyurethane elastomers, hydrogenated butadiene resins and mixtures thereof, and ionomer resins are particularly preferred.

The inner cover can be manufactured by a known method, such as injection molding or compression molding.

The thickness of the inner cover is preferably 0.5 mm or more, preferably 1.0 mm or more, and the upper limit is 2.0 mm or less. The inner cover preferably has a Shore D hardness of 40 or more, particularly 45 or more, with an upper limit of 55 or less.

On the other hand, the outer cover constitutes the outermost layer of the ball, and can be made of a known cover material. The cover material can be arbitrarily selected from, for example, ionomer resins, polyurethane resins, polyester resins, polyester elastomers, styrene elastomers, polyurethane elastomers, hydrogenated butadiene resins, balata rubber, etc. Among these, ionomer resins are preferred. preferable.

The outer cover preferably has a thickness of less than 1.0 mm. The thickness of the outer cover is preferably optimized together with the thickness of the inner cover. The outer cover preferably has a Shore D hardness of 50 or more, particularly 55 or more, and an upper limit of 65 or less, particularly 60 or less. The Shore D hardness of the outer cover is preferably optimized together with the Shore D hardness of the inner cover. is preferred. Golf balls shall comply with the Rules of Golf for competition use.

[Embodiment 2]
In order to improve the supportability of the grip to the club shaft, the grip material is formed from a rubber composition whose main component is, for example, a base rubber containing polybutadiene, polyisoprene, natural rubber, or silicone rubber as a main component. can be done. The grip of the golf club is made by mixing 100 parts by weight of synthetic rubber or natural rubber with 15 to 100 parts by weight of radium ore powder of 200 to 1000 becquerels per gram, vulcanizing it, and measuring the gamma ray at the time of contact with a gamma ray measuring instrument. A rubber material with a radiation dose of at least 3-20 mSv/y is used. The radium ore powder shown in Fig. 1 is mixed as a filler, rubber kneaded, quenched, and hardened uniformly. However, at least the hardness of the grip tip portion 22 is increased so that the gripping force up to the tip portion of the grip body 21 can be easily transmitted to the shaft, and excessive bending of the shaft can be controlled. Also, radium ore powder may be distributed throughout the grip to provide a hormesis effect with a gamma radiation dose of at least 3-20 mSv/y in the hand holding the grip.

Claims (1)

A rubber product that exerts a hormesis effect when it comes into contact with the body is a grip member of a golf club. In manufacturing this , radium is used as a filler to exert a hormesis effect by gamma ray irradiation and at the same time impart cross-linking properties to the rubber. An ore powder is selected, and 15 to 50 parts by weight of radium ore powder of 200 to 1000 becquerel per gram is mixed with 100 parts by weight of a rubber component made of synthetic rubber or natural rubber to prepare a rubber composition. The composition is rubber kneaded and quenched, and in combination with another vulcanizing agent, the rubber component in the rubber composition is crosslinked and vulcanized in cooperation with the gamma ray radiation of the radium ore powder mixed in the rubber composition. While adjusting the hardness of the vulcanized rubber product, the gamma ray radiation level of the vulcanized rubber product is adjusted in the range of 3 to 20 mSv/y at the time of contact with the gamma ray measuring instrument to give a hormesis effect. A method for manufacturing a rubber article that contacts the body using a gamma ray emitting rubber composition.

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