JPH0423551B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a synthetic fiber string used for rackets for hard and soft tennis, badminton, squash and the like.

[Background technology]

Conventionally, animal fibers such as cow or sheep intestine or whale muscle have been used for racket guts. For example, when using cow intestine, first cut the cow's intestine into linear bodies, twist 15 to 20 of these linear bodies and glue them with gelatin, urethane resin, etc. to obtain twisted threads. I try to use it as a gut. A racket using guts made of twisted yarns of animal fibers has excellent resilience, has little slack, produces a pleasant hitting sound, and gives the player a pleasant hitting feeling.

However, this product has the disadvantage of poor water resistance and is very expensive, so it has not achieved widespread general demand.

For this reason, at present, rackets using strings made of monofilament, which are excellent in water resistance and are inexpensive, are popular on the market, although they are somewhat unsatisfactory in terms of the feel the player receives, such as the sound and feel of the ball when hit.

However, recently, from the perspective of placing importance on the player's feel during play, guts made of multifilament that provide a soft feel have come into use.

However, it has been found that this material has the disadvantage that it cannot maintain the original resilience for a long time because it loosens significantly with use. For example, 30Kg, which corresponds to a typical tensioning tension.
Find the tension after continuously applying the tension for 1 hour,
From this, stress relaxation is calculated to be 83% for natural sheep, 73% to 82% for monofilament type nylon guts, and 65.3% to 65.3% for multifilament type.
It was 76.3%.

For this reason, there has been a desire for a racket string that has the above-mentioned advantages of the multifilament type but also has less slack, which is a drawback.

[Purpose of the invention]

This invention was made in view of the above circumstances, and has excellent repulsion properties, less slack, and
To provide a racket gut that produces a pleasant hitting sound and gives a player a pleasant hitting feeling, has excellent water resistance, and is inexpensive, and a manufacturing method thereof.

[Disclosure of the invention]

In order to achieve the above objectives of excellent resilience, pleasant hitting sound, and pleasant hitting feeling, the inventors decided to use a large number of twisted single fibers, that is, multifilament, and to achieve water resistance and low cost. , polyamide-based synthetic fibers are used for the fibers, and in order to eliminate slack in twisting, each single fiber, or filament, of the twisted yarn is adhered to each other, and in order to improve water resistance and durability, the outer periphery of the twisted yarn is coated with resin. It was discovered that it is sufficient to cover it with Furthermore, the present invention was completed based on the discovery that if an ultraviolet curable resin is used as the adhesive, the twisting can be fixed instantly, which is suitable for achieving the object of the present invention, and also has good workability.

Therefore, the first invention has a multifilament main body formed by twisting together a large number of polyamide synthetic fibers with a single thread fineness of 10 deniers or less, and the strands of the main body are fixed with an ultraviolet curable adhesive. The gist of the second invention is a racket gut whose outer periphery is coated with a resin layer with a thickness of 30 μm or more. In order to obtain a racket string in which the twisted parts of the main body are fixed with an adhesive and the outer periphery is covered with a resin layer, an ultraviolet curable resin is used as the adhesive, and the resin is impregnated. The gist of this invention is to provide a method for manufacturing racket strings in which polyamide synthetic fibers are twisted together in a stretched state and cured by irradiating ultraviolet rays.

Below, first, the first invention will be explained in detail.

FIG. 1 shows a racket gutt A according to the present invention.
An example of this is shown. As shown in the figure, in this racket string A, the individual twisted yarns of each single fiber of polyamide synthetic fiber are impregnated with adhesive and adhered to each other, and the outer periphery of the multifilament 1 is coated with a resin coating 2. Covered.

In addition, in order to improve the convergence of each filament and further improve the durability when hitting the ball, a fine monofilament is spirally wound around the outer periphery of the entire multifilament 1, and then the outer periphery is coated with resin. You may also do so.

For example, nylon can be used as the polyamide synthetic fiber. In this case, all nylons can be used, including nylon 6, nylon
66 or a copolymer thereof is desirable in terms of water resistance, fatigue resistance, etc. In order for the player to obtain a soft feeling when hitting a ball, the thickness of each single fiber, that is, the single filament fineness, is preferably about 2 to 9 d (denier); if it is 10 d or more, it becomes difficult to obtain a soft feeling. Further, the strength of the twisted yarn bundle is preferably 5 g/d or more, and the elongation is preferably about 10% to 30%. In order to obtain appropriate strength and cross-sectional shape, the number of twists is preferably 50 to 300 turns/m.

As the adhesive 2, any UV curable resin can be used in the present invention as long as it can effectively fix the twisting of the twisted yarn. The ultraviolet curable resin may contain a photopolymerizable prepolymer, a photopolymerizable monomer, and a photoinitiator, and may also contain a sensitizer, a pigment,
It may contain a filler, an inert organic polymer, a leveling agent, a thixotropic agent, a thermal polymerization inhibitor, and a solvent. Photopolymerizable prepolymers include polyester acrylate, polyurethane acrylate, epoxy acrylate,
Examples include polyether acrylate, oligoacrylate, alkyd acrylate, polyol acrylate, etc., but polyester acrylate, polyurethane acrylate, and epoxy acrylate are preferred, and polyurethane acrylate is particularly preferred from the viewpoint of soft feel and resilience. This polyurethane acrylate can be produced by reacting an acrylate having a hydroxy group with an isocyanate group-containing substance such as tolylene diisocyanate, and is an acrylic resin that has a polyester structure in the center of the molecule and isocyanate groups at both ends. It is.

The various acrylates described above turn into polymers with amide bonds in a short time when irradiated with ultraviolet rays,
It cures quickly and exhibits excellent adhesion to polyamide synthetic fibers such as nylon.

Examples of photoinitiators include sulfur compounds, acetophenones, and carbonyl compounds such as benzophenones.

Next, the second invention will be explained in detail.

A large number of polyamide synthetic fibers are impregnated with ultraviolet curable resin, twisted together and irradiated with ultraviolet rays to cure the fibers in a very short time, firmly fixing the twisting of each single fiber. The present invention may use ultraviolet light as long as it can effectively photopolymerize and cure the ultraviolet curable resin used as the adhesive. For example, the ultraviolet irradiation device is
A commercially available device that includes an ultraviolet lamp that generates ultraviolet light and a system that condenses the generated ultraviolet light and irradiates the object to be irradiated can be used.

In this invention, when twisting a large number of filaments to form the multifilament 1, each filament is impregnated with an ultraviolet curable resin in advance and irradiated with ultraviolet rays while being twisted to harden the impregnated resin in a short time. . This is because in the method of impregnating an ultraviolet curable resin after twisting, the resin does not sufficiently penetrate into the filaments inside the twisted yarn bundle, and therefore the filaments do not adhere to each other with sufficient strength. In addition, in this invention, the required number of filaments may be twisted together at once to form the multifilament 1 (main body), or the required number of filaments may be divided into portions and each loosely twisted in advance to form the multifilament. These lightly twisted multifilaments may be twisted together to form the main body. moreover,
In this invention, since the resin is cured in a short time by ultraviolet irradiation, the resin does not leak out from the fibers during twisting, and sufficient adhesion can be expected. Finally, the thickness is 30μm to prevent fatigue of the fibers during tensioning and hitting and improve durability.
The above resin is coated on the twisted yarn using a conventional method. As the resin in this case, nylon, urethane, etc. are particularly desirable from the viewpoint of water resistance and abrasion resistance.

(Example) Examples of the present invention will be described in detail below.

While twisting a nylon multifilament with a single thread fineness of 6d and 1350 single threads at a twist rate of 100 turns/m, triresin isocyanate and 2-hydroxyacrylate were added to the polyester of 1,6-hexanediol and adipic acid. The polyurethane acrylate obtained by the reaction is impregnated with an ultraviolet curable resin made by adding trimethylol and propanol acrylate as photopolymerizable monomers and benzophenone as a photoinitiator,
After passing through a 1.1 mmφ nozzle and constricting it, it was irradiated with ultraviolet rays using a high-pressure mercury lamp. The linear body thus obtained had a diameter of 1.14 mm. The outer periphery of this linear body was coated with nylon 6 by a conventional method to obtain a racket string. The diameter of the linear body after coating was 1.33 mm, and the thickness of the coating was about 100 μm. Moreover, the tensile strength was 75 kg and the elongation was 26%. 30Kg in this gut
When the stress relaxation rate after 1 hour was examined, it was 82.5%. From this, it was found that the racket string according to the present invention has extremely superior loosening resistance compared to general multifilament. In addition, as a result of actual trial shooting,
It was found that multifilament provides a soft feel at impact that cannot be obtained with monofilament. In addition, 60 strokes/minute between guts,
The number of strokes required for friction and cutting was investigated under the condition of a rubbing load of 2.7 kg. As a result, while the gutt using natural fibers had a score of 29, the one according to this invention had a score of 345 before coating.
It was 445 after coating. From this result, it was also found that the racket string according to the present invention has excellent wear resistance. Finally, when I soaked the guttu made from natural fibers in water and rubbed it with my fingers, it came apart.
The racket string according to the present invention does not unravel at all, and from this fact, it has been found that it can withstand use during play in rainy weather.

〔Effect of the invention〕

Since the racket gut according to the present invention is constructed as described above, it has excellent resilience, relaxation resistance, and fatigue resistance, emits a pleasant hitting sound, and gives the player a pleasant hitting feeling. Moreover,
It has excellent water resistance and is inexpensive.

In addition, in the method for manufacturing racket strings according to the present invention, the multifilament is impregnated with an ultraviolet curable resin in advance and is irradiated with ultraviolet rays while being twisted, so that the impregnated resin is cured in a short time, so that the adhesive is strong. This makes it possible to provide a racket string with excellent loosening resistance.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a racket string according to the present invention. A... Gut for racket, 1... Multifilament, 2... Resin coating.

Claims (1)

[Scope of Claims] 1. The main body is a multifilament made by twisting together a large number of polyamide synthetic fibers with a single thread fineness of 10 deniers or less, and the twists of the main body are fixed with an ultraviolet curable adhesive, and , the outer periphery is thick
Racket guts coated with a resin layer of 30μm or more. 2. To obtain a racket string having a main body made of a multifilament made by twisting together a large number of polyamide synthetic fibers, the above-mentioned twists of this main body being fixed with an adhesive, and the outer periphery being covered with a resin layer. In this method, a UV-curable resin is used as the adhesive, and polyamide synthetic fibers impregnated with the resin are twisted together and cured by irradiation with UV rays.