JPH0910368A - String for racket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a string for a racket capable of rising the commercial value by improving the transparency as well as prolonging the durability, by compounding aluminum borate whisker or particles into a surface resin coating layer. SOLUTION: This string 1 for a racket comprises a monofilament 2 being a core component fiber, monofilaments 3 around it, and surface resin coating layer 4 and 5 surrounding them. The surface resin coating layers 4 and 5 may be the same substance, and the surface resin coating layer 4 has a function of uniting the monofilament 2 as core component fiber and the monofilaments 3 as cover component fibers. With the surface resin coating layer 5, at least one kind of inorganic fillers selected from the whiskers or particles of aluminum borate are compounded by 1-30wt.%, and they exhibit an improving action on durability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket string for tennis, badminton, squash, etc., which is excellent in hitting performance and durability.

[0002]

2. Description of the Related Art Conventionally, strings for rackets such as tennis, badminton and squash have a playability.
The natural gut was used because of its superiority, but because of its poor durability, a string made of mono- or multi-filament made of synthetic fiber (Shinsa Tech) is used. Playability and durability (Durab), which are important characteristics required for this racket string,
ility) is inversely related and has the following relationship. (1) Durability; Natural gut <Sinsatech string made of multifilament <Sinsatech string made of monofilament (2) Hitting property; Natural gut ≧ Sinsatech string made of multifilament> Synthetic string made of monofilament That is, durability and hitting property are It was a mutually conflicting relationship and it was difficult to make them compatible. In particular, a racket string composed of a polyamide-based synthetic fiber multifilament has a hitting performance comparable to that of natural gut, but has a durability as compared with a monofilament synsatech string (for example, Japanese Patent Laid-Open No. 6-218081). Inferiorly, this improvement was requested. In addition, blending potassium titanate whiskers on the surface of a string using a monofilament as a core is disclosed in Japanese Patent Publication No.
No. 10 is proposed.

[0003]

However, the potassium titanate whiskers proposed by the above Japanese Patent Publication No. 2-56110 have a problem in hitting ability, and are basically inferior in transparency and have low commercial value. There was a problem.

In order to solve the above-mentioned conventional problems, it is an object of the present invention to provide a racket string which maintains high durability and has improved transparency to enhance commercial value.

[0005]

In order to achieve the above object, the racket string of the present invention has a monofilament arranged in a core portion, a plurality of monofilaments arranged around the monofilament, and a resin coating layer around the monofilament. In the existing racket string, the surface resin coating layer contains at least one inorganic filler selected from aluminum borate whiskers and aluminum borate particles in the range of 1.0% by weight or more and 30.0% by weight or less. It is characterized by

In the above-mentioned constitution, it is preferable that at least one inorganic filler selected from aluminum borate whiskers and aluminum borate particles is subjected to surface coupling treatment.

Further, in the above structure, it is preferable that the resin coating layer on the surface is made of polyamide resin or urethane resin. Further, in the above structure, the thickness of the monofilament in the core portion is 0.4 mm or more and 1.0 or more.
It is preferable that the thickness of the monofilament is not more than 0.1 mm, and the thickness diameter of the surrounding monofilament is not less than 0.1 mm and not more than 0.3 mm.

The whiskers have an average fiber length of 1 to 320.
One having an average fiber diameter of 0.1 μm, an average fiber diameter of 0.1 to 1.6 μm, and an aspect ratio (average fiber length / average fiber diameter) of 10 to 200 can be used as an example. More preferred whiskers are
Average fiber length 10 to 20 μm, average fiber diameter 0.2 to 0.5
μm, aspect ratio (average fiber length / average fiber diameter) 20 to
A range of 55 is preferred. In the case of particles, the average particle diameter is preferably in the range of 1 to 30 μm.

The surface coating resin is preferably a polyamide resin, a polyurethane resin or the like because of its adhesiveness to the polyamide-based synthetic fibers constituting the string and abrasion resistance. The whiskers or particles are mixed in a state where these resins are in a hot melt state.

The currently known whiskers include the following. Aluminum borate (9Al ₂ O ₃・ 2
B ₂ O ₃ , white needle crystal potassium titanate (K ₂ O ・ 6
TiO ₂ , white needle crystals, barium titanate (BaT)
iO ₃ , white needle crystals), silicon carbide (SiC, green needle crystals), silicon nitride (Si ₃ N ₄ , white needle crystals), zinc oxide (ZnO, tetrapot crystals), basic magnesium sulfate, Graphite, magnesia, calcium sulfate (Na ₂ C ₂ aP ₂ O ₁₈ ), magnesium borate, α-
Alumina, chrysotile, wollastonite, etc.

Among these whiskers, particularly useful for the racket string is the effect of improving durability,
Moreover, it is an aluminum borate whisker with excellent transparency similar to natural gut. Aluminum borate particles are similarly excellent in transparency. The aluminum borate whiskers and particles have a relatively low refractive index of 1.60 to 1.63, and when mixed with a polyamide resin or a polyurethane resin, their refractive indexes are close to each other and have high translucency and transparency. Sex is obtained.

The content of the inorganic filler is 1.0% by weight.
If it is less than the above, the effect of improving durability is not sufficient. On the other hand, if it exceeds 30% by weight, the elasticity of the coating layer decreases, and it is impossible to follow the expansion and contraction of the string for each hit ball, and cracks occur. It is recognized that it will decrease.

In addition to whiskers, the coating resin is not limited to containing other additives such as a leveling agent, a coloring agent, and a stabilizer. According to the present invention, the hitting property is good and the durability is also high. In addition, the stringability for the racket string, which is an important characteristic, is excellent, and it can be realized at low cost.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As the core fiber and the coated fiber used in the present invention, a polyamide synthetic fiber can be used. As the polyamide-based synthetic fiber, nylon 6, nylon 66, or a copolymer thereof is preferable because high strength can be easily obtained. Strength is 5g from the viewpoint of durability
/ Denier or more, and the elongation is preferably about 10 to 30%.

[0015] Then the preferred borate made of aluminum whiskers or particles used in the present invention, if Shimese by Formula is _{9AL 2 O 3 · 2B 2 O} 3, whiskers average fiber length 10 to 30 [mu] m, average fiber The diameter is 0.5-1.
0 μm, the particles have an average particle diameter of 3 to 100 μm.

If the amount is 1% by weight or less, the effect is difficult to obtain, and preferably 3% by weight or more is desirable. On the other hand, if the amount exceeds 30% by weight, the whole string becomes hard, which is not suitable for the soft ring which is the object of the present invention, and is 30% by weight or less, preferably 15% by weight or less. These effects not only improve the durability of the string, but also improve the stretchability, probably because of the smoothing of the surface. Aluminum borate is particularly useful because it has a lower refractive index than other materials and can form a transparent string.

Finally, in order to improve the durability during stretching and hitting, a resin having a thickness after drying of 30 μm or more and 150 μm or less is coated by a usual method. In this case, the resin is preferably nylon, polyurethane or the like from the viewpoint of durability.

Further, when a whisker made of aluminum borate is added to the above coating resin, the durability is further improved. Further, a smoothing agent such as wax and silicone oil is applied to obtain the final product.

FIG. 1 shows a model example of a cross section of a racket string 1 according to an embodiment of the present invention. FIG.
In, the racket string 1 includes a monofilament 2 that is a core component fiber, a monofilament 3 that is a coating component fiber around the core filament, and surface resin coating layers 4 and 5 around the monofilament 3. The surface resin coating layers 4 and 5 may be the same substance, and the surface resin coating layer 4 has a function of integrating the monofilament 2 of the core component fiber and the monofilament 3 of the coating component fiber. The surface resin coating layer 4 is an adhesive used during twisting.
The surface resin coating layer 5 exerts an action of improving durability by adding an inorganic filler (for example, whiskers).

Further, FIG. 2 shows a model example of the cross section of the racket string 11 according to another embodiment of the present invention. The difference from FIG. 1 is that the number of monofilaments 13 that are coating component fibers is large. That is, it is composed of a monofilament 12 that is a core component fiber, a monofilament 13 that is a coating component fiber around it, and surface resin coating layers 14 and 15 around it. The surface resin coating layer 14 is an adhesive used at the time of twisting, and the surface resin coating layer 14 has a function of integrating the monofilament 12 of the core component fiber and the monofilament 13 of the coating component fiber. Surface resin coating layer 1
No. 5 exhibits an effect of improving durability by adding an inorganic filler (for example, whiskers or particles).

[0021]

The present invention will be described in more detail with reference to the following examples. (Example 1) One nylon 6 monofilament having a diameter of 1.0 mm was used as the core component fiber, and 25 nylon 6 monofilaments having a diameter of 0.115 mm were wound as the covering component fibers in a spiral shape around the core component fiber. Attach it and fix it with nylon adhesive at the same time.
A 23 mm linear body was obtained.

Aluminum borate whiskers surface-treated with an alkylsilane coupling agent (average fiber length 20 μm, average fiber diameter 0.75 μm, aspect ratio (average fiber length / average fiber diameter) 27) were provided around the outer periphery of this linear body. Of 30% by weight of nylon 6,6 master pellet 30
Parts by weight and 70 parts by weight of ordinary nylon 6,6 pellets were mixed to obtain hot-melt nylon (whisker content 9
% By weight) to obtain a racket string by a conventional coating method.

The obtained racket string has a diameter of 1.
299 mm, tensile strength 82.2 kg, knot strength 45.7
The elongation was 1 kg and the elongation was 19.8%. The coating thickness was 100μ. The obtained string was transparent and had a high-class feel. A schematic sectional view is shown in FIG.

The string was stretched on a carbon fiber reinforced resin racket having a face area of 110 square inches with both vertical and horizontal threads under a tension of 60 pounds. The string tension and waist were moderate, the surface hardness was moderate, the slipperiness was good, and the stretchability was much better than the natural gut and even better than the comparative example containing no whiskers.

Then, hit an actual tennis ball,
The speed was 127 km / hour, the launch interval was 15 times / minute, and the launch distance was 50 cm until the string was cut. In a total of two tests, the number of times of ejection until cutting was 1,450 times and 1,464 times, respectively.

As a comparative example, a string obtained by the same method except that the whiskers of the above-mentioned example were not contained was subjected to the same method under other conditions, and the result was 938 times.

(Example 2) Core component fiber has a diameter of 1.0
mm nylon 6 monofilament is used, 44 nylon 6 monofilament having a diameter of 0.115 mm is wound around the core component fiber in a double spiral shape as a covering component fiber, and a nylon adhesive is used at the same time. And fixed to obtain a linear body having a diameter of 1.23 mm.

Using this linear material, hot-melt nylon 6 containing 6% by weight of aluminum borate particles (average particle diameter 3 μm) on the outer periphery was coated by a conventional method to obtain a racket string. .

Diameter of the obtained racket string 1.
310 mm, tensile strength 72.1 kg, knot strength 40.2
It was kg and the elongation was 19.0%. The coating thickness is
It was about 100μ. The obtained string was transparent and had a high-class feel. A schematic sectional view is shown in FIG.

The durability of this string was examined by the same method as in the above-mentioned embodiment. The tension, waist and surface hardness of the string were moderate, the slipperiness was good, and the stretchability was very good. In a total of two tests, the number of times of ejection until cutting was 1242 times and 1220 times, respectively.

[0031]

As described above, according to the present invention, in the racket string in which the monofilament is arranged in the core portion, a plurality of monofilaments are arranged around the core filament, and the resin coating layer is present around the monofilament. The surface resin coating layer contains at least one inorganic filler selected from aluminum borate whiskers and aluminum borate particles in a range of 1.0% by weight or more and 30.0% by weight or less, thereby maintaining high durability. In addition, it is possible to provide a racket string with improved transparency and commercial value.

[Brief description of the drawings]

FIG. 1 is a model cross-sectional view of a racket string according to a first embodiment of the present invention.

FIG. 2 is a model cross-sectional view of a racket string according to a second embodiment of the present invention.

[Explanation of symbols]

1,11 Racket string 2,12 Multi-filament fiber of multiple polyamide synthetic fibers 3,13 Adhesive resin layer used during twisting 4,14 Surface resin coating layer with whiskers added

Claims (4)

[Claims] 1. A racket string in which a monofilament is arranged in a core portion, a plurality of monofilaments is arranged around the core portion, and a resin coating layer is present around the monofilament, and in the surface resin coating layer, aluminum borate whiskers and A racket string, wherein at least one inorganic filler selected from aluminum borate particles is blended in a range of 1.0% by weight or more and 30.0% by weight or less. 2. The racket string according to claim 1, wherein at least one inorganic filler selected from aluminum borate whiskers and aluminum borate particles is subjected to a surface coupling treatment. 3. The racket string according to claim 1, wherein the resin coating layer on the surface is a polyamide resin or a urethane resin. 4. The thickness diameter of the core monofilament is in the range of 0.4 mm or more and 1.0 mm or less, and the thickness diameter of the surrounding monofilaments is in the range of 0.1 mm or more and 0.3 mm or less. The racket string described.