JP2007181553A - String for racket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a string for a racket which is excellent in ball hitting durability, and in addition, can provide a good ball hitting feeling. <P>SOLUTION: This string 1 for the racket is constituted by providing a resin coating layer 4 around a filament 2 made of a synthetic resin. In the string 1 for the racket, the resin coating layer 4 contains at least a synthetic resin, and a solid coaxial multilayer structure type ultra-thin carbon fiber which is contained in the synthetic resin, and is concentrically overlaid with graphene sheet cylinders to a cylinder core section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a racquet string (also referred to as gut) made of synthetic resin fibers used in various rackets such as tennis, badminton, soft tennis, squash and the like.

  As a string for rackets, natural gut made from sheep intestines and whale muscles was used in the old days. Although these natural guts have excellent resilience and excellent performance such as giving a player a pleasant shot feeling, natural guts have a problem of poor moisture resistance and short service life.

  In contrast to such natural guts, in recent years, a string using a synthetic filament monofilament or multifilament such as polyamide as a core component, or a core-sheath structure in which a side yarn of a synthetic fiber such as polyamide is wound around the core component. Synthetic fiber strings are widely used as racket strings because of their excellent durability.

  However, as the performance of the racket is improved, a string having a longer hitting durability and a longer life is required. Thus, various proposals have been made for the purpose of imparting excellent hitting durability by using a composite resin for the surface coating layer of the string.

  For example, Patent Document 1 discloses that a core component is formed of a single monofilament made of a synthetic fiber having a specific thickness for the purpose of obtaining a racket gut having a good shot feeling and excellent durability and resilience. The intermediate layer is formed of a plurality of monofilaments having a specific proportion of thickness relative to the monofilament of the core component, and the outer layer has a specific number of microfibers of a specific thickness made of synthetic fibers with respect to the total fiber amount. A technique is disclosed in which the outermost peripheral surface is coated with a surface coating layer containing metal powder formed by multifilaments used up to 60% by weight. Thereby, durability and resilience can be improved without impairing the original shot feeling and vibration absorption.

  Patent Document 2 discloses that a nylon monofilament is arranged in a core portion and has a plurality of surroundings for the purpose of obtaining a string for a racket that maintains durability and improves transparency and increases commercial value. In a racket string in which a nylon monofilament is arranged and a nylon resin coating layer is present around the nylon monofilament, a technique of adding 1 to 30% by weight of aluminum borate whisker to the surface resin coating layer is disclosed.

  However, in Patent Document 1, the diameter of the synthetic fiber that forms the outer layer, particularly the microfiber of the polyamide fiber, is as small as about 10 to 50 μm. In particular, there is a problem that durability is greatly reduced due to wear. Furthermore, even when the surface coating layer contains a metal powder such as titanium powder in order to improve durability, the thermal conductivity of the gut itself is lowered, so the vibration of the gut generated at the time of ball impact is consumed as thermal energy. As a result, it is predicted that the vibration damping property of the gut is poor and it is difficult to obtain a good shot feeling.

  Moreover, in patent document 2, since the heat conductivity of the said aluminum borate whisker itself is low, there exists a problem that friction heat which generate | occur | produces in the cross | intersection part of a string is not easily radiated, and wear advances by accumulation | storage of friction heat.

Therefore, there is one using a material that easily radiates frictional heat (see, for example, Patent Document 3). In Patent Document 3, for the purpose of obtaining a string that can suppress wear over a long period of time and has a good shot feeling, it has a fine hollow portion at the center and a thermal conductivity of 1,000 to 3. A technique is disclosed in which fine carbon fibers such as carbon nanofibers or carbon nanotubes having a fiber diameter of 10 to 300 nm at 1,000 W / (m · K) are mixed into the surface coating resin layer and / or the adhesive layer. Since the fine carbon fiber has high thermal conductivity and excellent heat dissipation characteristics, it can prevent wear of the surface coating resin layer due to frictional heat, improve vibration damping and obtain a good shot feeling. Is possible.
Japanese Patent No. 3166031 Japanese Patent No. 3025431 Japanese Patent Laid-Open No. 2004-202000

In Patent Document 3, the fine carbon fibers are preferably mixed in the surface coating resin layer in the range of 0.5 to 10% by weight, particularly in the range of 1 to 5% by weight. However, the inventor of the present application stretched the string with a tension of 60 pounds in the warp and weft threads on a carbon fiber reinforced resin racket having a face area of 100 cm ² for the string having the configuration described in Patent Document 3, When a tennis ball was launched, and a hitting test was performed at a hitting portion racket speed of 81 km / hour and a hitting interval of 18 times / minute was performed, and the surface of the coating resin layer was observed, the content of the fine carbon fiber was 1% by weight. When exceeded, the fine carbon fiber was excessively exposed on the surface of the string to the extent that it was visible to the naked eye. This is presumably because the dispersion state of the fine carbon fibers in the surface coating resin layer deteriorates and the adhesive strength deteriorates. Therefore, in the string described in Patent Document 3, it is predicted that it is difficult to suppress the wear of the string over a long period of time.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a racket string that is excellent in hitting durability and can obtain a good shot feeling.

The racquet string according to the present invention is a racquet string provided with a resin coating layer on an outer peripheral surface. The resin coating layer is contained in at least a synthetic resin and the synthetic resin, for example, an arc discharge method, a high frequency plasma combustion. The graphene sheet cylinder synthesized by the method and the template method includes a solid coaxial multi-layer structure type ultrafine carbon fiber that is laminated concentrically to the center of the cylinder.
Thereby, the string for rackets which is excellent in hit ball durability and can obtain a good shot feeling can be provided.

In the racket string of the present invention, the ultrafine carbon fiber preferably has a diameter of 1 to 100 nm and a length of 1 μm or more.
In general, as the diameter of the ultrafine carbon fiber is narrower or the length is longer, the characteristic performance of the ultrafine carbon fiber is exhibited. From a practical aspect, the ultrafine carbon fiber has a diameter of less than 1 nm. However, the durability of the ultrafine carbon fiber itself is low, and even when mixed with a synthetic resin, sufficient strength cannot be imparted. Moreover, if the length of the ultrafine carbon fiber is less than 1 μm, sufficient strength cannot be imparted even when mixed with a synthetic resin.

Moreover, the string for rackets of this invention WHEREIN: It is preferable that the said ultra-fine carbon fiber is 0.01 to less than 0.5 weight% with respect to the said synthetic resin.
If the content of the ultrafine carbon fiber with respect to the synthetic resin is less than 0.01% by weight, the amount is too small to give sufficient strength to the string. It is predicted that it is difficult to suppress wear over a long period of time because the ultrafine carbon fibers are exposed on the string surface due to the deterioration of force.

  In the racket string of the present invention, a side thread is spirally wound around the outer periphery of the core thread, the core thread and the side thread are integrally bonded with an adhesive, and the resin coating layer is formed on the outer periphery thereof. It can be set as the provided structure.

The racket string according to the present invention includes a core yarn, an intermediate layer formed of a plurality of filaments wound around the outer periphery of the core yarn and integrally bonded with an adhesive, and a spiral shape on the outer periphery of the intermediate layer. And an outer layer composed of a plurality of filaments integrally bonded with an adhesive, and the resin coating layer is provided on the outer periphery of the outer layer.
By using such a multi-layer structure, the width of the combination of filaments and the like is widened, and thus a string having a characteristic hitting performance can be manufactured.

Moreover, the string for rackets of this invention WHEREIN: The said resin coating layer can also be set as the structure containing the multiple side thread by which the string-making process was carried out, and was integrally adhere | attached with the adhesive agent.
Thus, it is possible to provide a racket string that has a good and characteristic hitting performance even if it is relatively thin. In particular, it is suitable as a badminton string.

Moreover, the string for rackets of this invention WHEREIN: By containing a dispersing agent with the said ultrafine carbon fiber in the said resin coating layer, the dispersibility of the said ultrafine carbon fiber can be improved.
Thereby, since the dispersibility of the ultrafine carbon fiber can be improved, the ultrafine carbon fiber can be dispersed almost uniformly. As a result, it is possible to sufficiently exhibit the excellent characteristics of the ultrafine carbon fiber in the synthetic resin, and it is possible to provide a racket string that is excellent in hitting durability and can obtain a good shot feeling.

  According to the present invention, a graphene (a plane or an aspect formed by two-dimensionally arranging carbon six-membered rings) sheet cylinders are stacked concentrically up to the center of a cylinder on a resin coating layer formed using a synthetic resin. By including the ultrafine carbon fiber having a solid coaxial multilayer structure, it is possible to obtain a racket string that is excellent in hit ball durability and has a good shot feeling.

  As a result of intensive studies, the present invention has shown that a graphene (planar or phase formed by two-dimensionally arranging six-membered carbon rings) sheet cylinders in a concentric cylinder form on a resin coating layer using a synthetic resin. An ultrafine carbon fiber having a solid coaxial multilayer structure that is densely laminated to the center is contained. Thereby, it is possible to obtain a string for a racket that is superior in ball hitting durability and has a good shot feeling compared to the case of containing a hollow ultrafine carbon fiber having a fine cavity in the center.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a racket string according to the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
The string according to the first embodiment will be described in detail with reference to FIG.
As shown in FIG. 1, a core yarn 2 made of a substantially cylindrical monofilament is disposed at the center of the string 1. A side thread 3 made of a plurality of monofilaments is spirally wound around the outer periphery of the core thread 2. The core yarn 2 and the side yarn 3 are integrally bonded with an adhesive. A resin coating layer 4 containing ultrafine carbon fibers is formed on the outer periphery of the side yarn 3. As described above, the string 1 has a three-layer structure including the core yarn 2, the side yarn 3, and the coating layer 4, and the outer shape thereof is a columnar shape.

  Synthetic monofilaments, multifilaments or multimonofilaments used for the core yarn 2 include polyamide (nylon 6, nylon 66, nylon 12, etc.), polyester (polybutylene terephthalate, polyethylene terephthalate, etc.), polyolefin, polyphenylene sulfide, Highly rigid filament fibers such as polyetheretherketone are preferred. In particular, it is preferable to use nylon 6 and nylon 66 polyamide fibers.

  Synthetic monofilaments, multifilaments or multimonofilaments used for the side yarn 3 include polyamide (nylon 6, nylon 66, nylon 12, etc.), polyester (polybutylene terephthalate, polyethylene terephthalate, etc.), polyolefin, polyphenylene. Highly rigid filament fibers such as sulfide and polyetheretherketone are suitable. In particular, it is preferable to use nylon 6 or nylon 66 polyamide fibers.

  Moreover, as a synthetic resin used for the resin coating layer 4, a polyamide resin and a urethane resin, a polyester resin (polyethylene terephthalate, nylon 6, nylon 66, nylon 12, or any two or more of these are used. Polyethylene naphthalate, polybutylene terephthalate, polylactic acid, etc.) are preferred. In particular, it is preferable to use a polyamide-based resin.

  The ultrafine carbon fibers contained in the resin coating layer 4 are so-called carbon nanotubes or carbon nanofibers. For example, graphene (carbon six carbon) synthesized by an arc discharge method, a high-frequency plasma combustion method, or a template method is used. A flat or curved surface formed by two-dimensionally arranging member rings) is a solid coaxial multi-layer structure type ultrafine carbon fiber in which sheet cylinders are densely stacked concentrically to the center of the cylinder. The ultrafine carbon fiber has a diameter of 1 to 100 nm and a length of 1 μm or more. Further, an ultrafine wire may be inserted in the center of the ultrafine carbon fiber.

  The content of the ultrafine carbon fiber is preferably 0.01% by weight or more and less than 0.5% by weight, particularly preferably 0.05 to 0.3% by weight, based on the synthetic resin. If the ultrafine carbon fiber content is less than 0.01% by weight, sufficient durability cannot be obtained. On the other hand, when the content is 0.5% by weight or more, the dispersion state of the fine carbon fibers deteriorates and the adhesive strength deteriorates, so that the fine carbon fibers are exposed on the surface of the string and the hit ball durability is lowered. The feeling characteristics are inferior.

  In the present invention, when the ultrafine carbon fiber is contained in the synthetic resin, a good nanocomposite resin can also be produced by dispersing the ultrafine carbon fiber almost uniformly using a dispersant.

  As the dispersant used in this case, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant are used, and a nonionic surfactant is preferably used. Furthermore, any nonionic surfactant of fatty acid type, higher alcohol type, or alkylphenol type may be used, but particularly preferred is a fatty acid type nonionic surfactant. Examples of the fatty acid nonionic surfactant include sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkanolamide and the like.

  The content of the dispersant can be appropriately determined depending on the content of the ultrafine carbon fiber, but is preferably 1 to 10 times, particularly preferably 3 to 7 times the amount of the ultrafine carbon fiber. If the amount is less than 1-fold, the amount of the dispersant for the ultrafine carbon fibers is insufficient, so that some of the ultrafine carbon fibers aggregate to form a precipitate. On the other hand, when the amount exceeds 10 times, the dispersant is adsorbed on the synthetic resin or there is an unadsorbed dispersant, and the hit ball durability is lowered.

  The arc discharge method is a method in which arc discharge is performed between two carbon materials and carbon is evaporated by the heat of the arc.

  The high-frequency plasma combustion method is a method for directly evaporating a carbon material using high-frequency plasma.

  The template method is a method in which organic molecules are inserted into fine pores of the template, and then the template is thermally decomposed to carbonize the filler.

  As described above, according to the first embodiment, the resin coating layer contains the ultrafine carbon fiber in an amount of 0.01% by weight or more and less than 0.5% by weight, and a dispersant is added in an amount of 1 to By containing 10 times the amount, it is possible to obtain a racket string having excellent hitting durability and having a good shot feeling.

(Embodiment 2)
As shown in FIG. 2, a core yarn 12 made of a substantially cylindrical multifilament is disposed at the center of the string 11. An intermediate layer 15 made of a plurality of monofilaments is spirally wound in a single layer around the outer periphery of the core yarn 12. The core yarn 12 and the intermediate layer 15 are integrally bonded with an adhesive. An outer layer 16 made of a plurality of monofilaments is spirally wound around the outer periphery of the intermediate layer 15 as a single layer. Then, on the outer periphery of the outer layer 16, a resin coating layer 4 containing ultrafine carbon fibers similar to that in the first embodiment is formed. As described above, the string 11 has a four-layer structure including the core yarn 12, the intermediate layer 15, the outer layer 16, and the coating layer 4, and the outer shape thereof is cylindrical.

  With this configuration, it is possible to provide a racket string having a characteristic hitting performance that is different from that of the first embodiment, for example, having both flexibility and durability.

(Embodiment 3)
As shown in FIG. 3, a core yarn 22 made of a substantially columnar multi-monofilament is disposed at the center of the string 21. An intermediate layer 25 composed of a plurality of monofilaments is spirally wound around the core yarn 22 in a single layer. The core yarn 22 and the intermediate layer 25 are integrally bonded with an adhesive. An outer layer 26 composed of a plurality of multifilaments is spirally wound around the outer periphery of the intermediate layer 25 in a single layer. Then, on the outer periphery of the outer layer 16, a resin coating layer 4 containing ultrafine carbon fibers similar to that in the first embodiment is formed. As described above, the string 21 has a four-layer structure including the core yarn 22, the intermediate layer 25, the outer layer 26, and the coating layer 4, and the outer shape thereof is cylindrical. The multi-monofilament is configured by converging a plurality of monofilaments having relatively small diameters.

  With this configuration, it is possible to provide a string for a racket having a characteristic hitting performance different from the first and second embodiments, for example, having both resilience and controllability. It is particularly suitable as a soft tennis string.

(Embodiment 4)
As shown in FIG. 4, a core yarn 32 made of a substantially columnar monofilament is disposed at the center of the string 31. Side threads 33 made of a plurality of monofilaments are braided on the outer periphery of the core yarn 32 in the form of braids. And the resin coating layer 34 containing the ultra fine carbon fiber similar to the said Embodiment 1 is formed in the outer periphery of the core thread 32 so that the side thread 33 may be included. As described above, the string 31 has a three-layer structure including the core yarn 32, the side yarn 33, and the coating layer 34, and the outer shape thereof is a columnar shape.

  With this configuration, it is possible to provide a racket string that has a good and characteristic hitting performance even if it is relatively thin. In particular, it is suitable as a badminton string.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to the following Example.

<Example 1>
As shown in FIG. 1, a nylon 6 monofilament having a diameter of 0.93 mm is used as the core yarn 2, and 16 nylon 6 monofilaments having a diameter of 0.2 mm are spirally wound around the core yarn 2 as the side yarn 3. The string yarn portion was constructed by integrally bonding using an adhesive for nylon.

  A graphene sheet cylinder with a diameter of 5 to 35 nm and a length of 1 μm or more, which is synthesized by performing arc discharge between two carbon materials and evaporating carbon with the heat of the arc, is densely stacked in a concentric cylinder shape to the center of the cylinder The outer circumference of the side yarn 3 is made of a polyamide-based resin composed of a nylon copolymer of nylon 6 and nylon 12 containing 0.05% by weight of a solid coaxial multilayer structure type ultrafine carbon fiber as a resin coating layer 4 having a thickness of 10 μm. The string 1 having a diameter of 1.35 mm was produced by coating the film.

  As a result of measuring Young's modulus (longitudinal elastic modulus) with respect to the mechanical properties of the solid coaxial multi-layer structure type ultrafine carbon fiber by, for example, evaluation by manipulation in a transmission electron microscope (TEM), 1,500-2 500 GPa.

<Example 2>
In Example 1, a nylon copolymer of nylon 6 and nylon 12 containing 0.05% by weight of a solid coaxial multilayer structure type ultrafine carbon fiber was used. In Example 2, a solid coaxial multilayer structure type ultrafine fiber was used. A polyamide-based resin made of a nylon copolymer of nylon 6 and nylon 12 containing 0.1% by weight of carbon fiber was used as the resin coating layer 4. Except for this, a string was produced in the same manner as in Example 1.

<Example 3>
In Example 1, a nylon copolymer of nylon 6 and nylon 12 containing 0.05% by weight of a solid coaxial multilayer structure type ultrafine carbon fiber was used. In Example 3, a solid coaxial multilayer structure type ultrafine fiber was used. A polyamide-based resin comprising a nylon copolymer of nylon 6 and nylon 12 containing 0.1% by weight of carbon fiber and 0.5% by weight of a fatty acid-based nonionic surfactant was used as the resin coating layer 4. Except for this, a string was produced in the same manner as in Example 1.

<Example 4>
In Example 1, a nylon copolymer of nylon 6 and nylon 12 containing 0.05% by weight of a solid coaxial multilayer structure type ultrafine carbon fiber was used. In Example 4, a solid coaxial multilayer structure type ultrafine fiber was used. A polyamide resin comprising a nylon copolymer of nylon 6 and nylon 12 containing 0.3% by weight of carbon fibers and 1.5% by weight of a fatty acid-based nonionic surfactant was used as the resin coating layer 4. Except for this, a string was produced in the same manner as in Example 1.

<Example 5>
In Example 1, a nylon copolymer of nylon 6 and nylon 12 containing 0.45% by weight of a solid coaxial multilayer structure type ultrafine carbon fiber was used, but in Example 5, a solid coaxial multilayer structure type ultrafine fiber was used. A polyamide resin composed of a nylon copolymer of nylon 6 and nylon 12 containing 0.45% by weight of carbon fiber and 2.25% by weight of a fatty acid-based nonionic surfactant was used as the resin coating layer 4. Except for this, a string was produced in the same manner as in Example 1.

<Example 6>
In Example 1, a nylon copolymer of nylon 6 and nylon 12 containing 0.05% by weight of a solid coaxial multilayer structure type ultrafine carbon fiber was used. In Example 6, a solid coaxial multilayer structure type ultrafine fiber was used. A polyamide-based resin composed of a nylon copolymer of nylon 6 and nylon 12 containing 1.0% by weight of carbon fiber was used as the resin coating layer 4. Except for this, a string was produced in the same manner as in Example 1.

<Example 7>
In Example 1, a nylon copolymer of nylon 6 and nylon 12 containing 0.05% by weight of a solid coaxial multilayer structure type ultrafine carbon fiber was used. In Example 7, a solid coaxial multilayer structure type ultrafine fiber was used. A polyamide resin made of a nylon copolymer of nylon 6 and nylon 12 containing 1.5% by weight of carbon fiber was used as the resin coating layer 4. Except for this, a string was produced in the same manner as in Example 1.

<Comparative Example 1>
As shown in FIG. 1, a nylon 6 monofilament having a diameter of 0.93 mm is used as the core yarn 2, and 16 nylon 6 monofilaments having a diameter of 0.2 mm are spirally wound around the core yarn 2 as the side yarn 3. The string yarn portion was constructed by integrally bonding using an adhesive for nylon.
A string resin 1 having a diameter of 1.35 mm was produced by coating the outer periphery of the yarn portion with a polyamide-based resin made of a nylon copolymer of nylon 6 and nylon 12 as the resin coating layer 4.
That is, a string in which the ultrafine carbon fiber was removed from the coating of Example 1 was produced.

<Comparative example 2>
Nylon co-polymerization of nylon 6 and nylon 12 containing 0.1% by weight of hollow coaxial multilayer structure type ultrafine carbon fiber having a diameter of 10 to 30 nm and a length of 100 nm or more, synthesized by chemical vapor deposition (CVD) A string was produced in the same manner as in Comparative Example 1 except that a polyamide-based resin composed of a coalescence was used as the resin coating layer 4.
In addition, as a result of measuring the Young's modulus of the said hollow coaxial multilayer structure type ultra fine carbon fiber, it was 400-600 GPa.

  Using the strings produced in the above examples and comparative examples, the string performance was evaluated by the following durability test and actual hit test.

(Durability test)
A string is stretched on a carbon fiber reinforced resin racket with a face area of 100 cm ² with a tension of 60 pounds for both warp and weft threads, and an actual tennis ball is launched on the racket. The racket speed is 81 km / hour and the launch interval is 18 times / minute. I kept hitting until the string was cut.

(Actual test)
In the above durability test, an actual hit test was performed using a racket in which a string was stretched, and the hit feeling at the time of hitting the ball felt by the player was evaluated.

  Table 1 shows the number of times until cutting in the durability test (number of cut balls) and the evaluation results of the hit feeling in the actual hit test.

From Table 1, in Examples 1 to 6 containing a solid coaxial multilayer structure type ultrafine carbon fiber in the resin coating layer, the number of cut balls of the string is increased as compared with Comparative Example 1 not containing the ultrafine carbon fiber, and the hitting durability. It can be seen that the shot feel is excellent. However, in Example 7 in which the content of the solid coaxial multilayer structure type ultrafine carbon fiber is 1.5% by weight, the number of cut balls of the string is reduced, the hit ball durability is lowered, and the shot feel is also deteriorated. You can see that Further, in Example 6 in which the content of the solid coaxial multilayer structure type ultrafine carbon fiber is 1.0% by weight, although the hit ball durability is superior to that of Comparative Example 1, the shot feeling is deteriorated.
From the above, the content of the solid coaxial multilayer structure type ultrafine carbon fiber is preferably 0.01% by weight or more and less than 0.5% by weight.

  Further, in Comparative Example 2 using the hollow coaxial multilayer structure type ultrafine carbon fiber, the number of cut spheres of the string is slightly increased as compared with Comparative Example 1 not containing the ultrafine carbon fiber, but the content of the ultrafine carbon fiber is the same. As compared with Example 2 that is, the number of cut spheres of the string decreased. As described above, the hollow coaxial multi-layer structure type ultrafine carbon fiber has a Young's modulus (1,500 to 2500 GPa), which is a Young's modulus (400 of a hollow ultrafine carbon fiber having a fine cavity in the center. ˜600 GPa), which is considered to be because of excellent mechanical properties.

Table 1 is shown below.

  In addition, although the Example 1-7 about Embodiment 1 was described in the said Example, Embodiment 2-4 is also the solid coaxial multilayer structure type extra fine carbon fiber similarly to Embodiment 1. The resin coating layer to be contained is provided, and it is considered that the same results as in Examples 1 to 7 described above can be obtained in the examples of Embodiments 2 to 4.

  The racquet string of the present invention has a longer life and superior hitting durability as compared to conventional racquet strings, and has excellent feeling characteristics when hitting a ball, such as tennis, badminton, soft tennis, squash, etc. It can be used for various rackets.

Sectional drawing of the string concerning Embodiment 1 of this invention. Sectional drawing of the string concerning Embodiment 2 of this invention. Sectional drawing of the string concerning Embodiment 3 of this invention. Sectional drawing of the string concerning Embodiment 4 of this invention.

Explanation of symbols

1, 11, 21, 31 String 2, 12, 22, 32 Core yarn 3, 33 Side yarn 4, 34 Resin coating layer 15, 25 Intermediate layer 16, 26 Outer layer

Claims (7)

In the racket string provided with a resin coating layer on the outer peripheral surface,
The resin coating layer includes at least a synthetic resin and a solid coaxial multilayer structure type ultrafine carbon fiber that is contained in the synthetic resin and in which a graphene sheet cylinder is stacked concentrically to the center of the cylinder. A string for rackets characterized by The racket string according to claim 1, wherein the ultrafine carbon fiber has a diameter of 1 to 100 nm and a length of 1 µm or more. The racket string according to claim 1 or 2, wherein the ultrafine carbon fiber is contained in an amount of 0.01 wt% or more and less than 0.5 wt% with respect to the synthetic resin. The side yarn is spirally wound around the outer periphery of the core yarn, the core yarn and the side yarn are integrally bonded with an adhesive, and the resin coating layer is provided on the outer periphery thereof. The string for rackets according to claim 3. A core yarn, an intermediate layer formed of a plurality of filaments wound around the outer periphery of the core yarn and integrally bonded with an adhesive, and a spiral wound around the outer periphery of the intermediate layer and integrated with the adhesive The racket string according to any one of claims 1 to 3, further comprising an outer layer made of a plurality of bonded filaments, wherein the resin coating layer is provided on an outer periphery of the outer layer. The racquet string according to any one of claims 1 to 3, wherein the resin coating layer includes a plurality of side threads that are formed into a string and are integrally bonded with an adhesive. The said resin coating layer contains a dispersing agent with the said ultra-fine carbon fiber, The string for rackets in any one of Claims 1-3 characterized by the above-mentioned.

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