JPS6215239B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a racket string, and more particularly to a string attached to a frame of a racket suitable for sports such as tennis, badminton, and squash. Conventionally, the guts of rackets used in the above-mentioned competitions are made from animal sinew, such as sheep intestines or whales, twisted to an appropriate degree and then processed to form bristles. However, this animal muscle gut is not moisture resistant,
Moreover, it has disadvantages such as the production quantity is limited due to resources and there are difficulties in supply sources, and properties such as breaking strength and tensile modulus are difficult to be uniform depending on the raw material, and it is also expensive. There is. Racket strings made of synthetic fibers have been developed that have eliminated the disadvantages of animal string strings in terms of moisture resistance, variability, availability, and price. It has a smaller tensile modulus than Gatsuto, and its mode has drawbacks. To explain this in more detail, the tensile modulus mode of animal muscle elongates in almost direct proportion to the tensile load, whereas in the case of synthetic fibers, there is little or no elongation in the range of small tensile loads, and a certain tensile modulus It has the characteristic of rapidly elongating when the load reaches a certain value. (See Figure 3) For this reason, in the case of conventional synthetic fibers, the elongation may vary greatly depending on the strength of the ball and the way it is hit. It is desirable for tennis guts to have not only high strength but also a large modulus, and its mode is also directly proportional to the elongation rate. On the other hand, a synthetic fiber filament with a rough surface is coated with a treatment agent consisting of a glue that maintains its tackiness and a small amount of filler that helps impart friction properties, resulting in better friction properties (specially used tennis guts). Kosho 43
-29283 Publication) and synthetic fiber multifilament which is twisted appropriately and the surface layer is heat-sealed with a stretch of 0% or more (Japanese Unexamined Patent Publication No. 48-45347). However, none of these methods could fundamentally improve the drawbacks of synthetic fibers, and their tensile modulus is low and the elongation mode has not been improved, so they are still inferior to animal muscle fibers. Furthermore, in order to correct this drawback, attempts have been made to mix metal wires such as wires into synthetic fibers, but since the specific stiffness of metal wires is small, if the addition is sufficient to obtain the effect of mixing, the resulting gutt will be It has the disadvantage of being heavy and lacking in flexibility. Therefore, it was necessary to take measures such as reducing the wire diameter of the strings to prevent an increase in the weight of the racket, and changing the way the strings were tensioned. In addition, conventionally, with regard to repulsive force, if the gut is stretched beyond the range where the tension and the strain caused by the tension are proportional, the repulsive force will decrease and the flight will be poor. Furthermore, if the gut is stretched loosely within the range where the tension and the strain caused by the tension are proportional, the repulsive force will increase. Therefore, the present inventors conducted research with the aim of combining the advantages of animal muscle string and synthetic fiber string, and also provided an excellent racket string that has never existed before. The above-mentioned racket string is made by twisting carbon fiber multifilament, which is made by bundling several carbon fibers in one direction, and nylon multifilament, which is made by bundling many fine nylon filaments in one direction, and coating the obtained fibers with nylon resin. The present invention was completed based on the knowledge that the object could be achieved. It is particularly preferable to use carbon fibers having high strength (150 Kg/mm ² or more), high elasticity (14 t/mm ² or more), and an elongation of 1 to 4%. At this time, carbon fiber multifilament and nylon multifilament are twisted together by combining the high tensile strength and low elongation properties of carbon fiber with the high elongation properties of nylon fiber. This is to create a structure with characteristics suitable for tennis guts through supplementary and synergistic effects. Furthermore, since the carbon fiber multifilament is an aggregate of fine particles, it can be easily twisted and twisted with the nylon multifilament even though the carbon fiber has high elasticity and high strength. To strengthen a combination of various fibers with resin, the combined fibers are passed through a molten resin.
The surface of the fibers may be coated with a resin layer, or each fiber may be coated with a resin layer. Coating with nylon resin in this way not only creates excellent firmness by highly replenishing each other and exhibiting a synergistic effect, but also coats carbon fiber with low frictional abrasion strength with nylon.
The surface is protected and strengthened from abrasion caused by friction, and carbon fiber multifilament and nylon multifilament are twisted together and coated with nylon resin to prevent untwisting, which can cause strings to break, and improve waterproofness. It also has many effects of smoothing the surface. By twisting and twisting the carbon fiber multifilament and the nylon multifilament in this manner, and further coating them with nylon resin, an excellent effect as a tennis string is produced. This embodiment will be explained in the drawings. FIG. 1 is an enlarged cross-sectional view of a gut according to an embodiment of the present invention, in which carbon fiber multifilament 1 and nylon multifilament 2 are twisted at a ratio of 3 to 1 each and covered with nylon resin 3. The second
The figure is a sectional view taken along the line -' in FIG. 1. Furthermore, FIG. 3 shows the results of a tensile test of the gutts of the present invention and the gutts of other products. The material of the racket gut of the present invention is easily available, inexpensive, and has excellent moisture resistance.
In addition, the product has little variation, has excellent moldability, and can have a tensile modulus appropriately larger than that of animal muscle guts, and can have elongation mode characteristics almost the same as animal muscle guts. Can be used stably for a long period of time. In other words, it is possible to combine the advantages of animal muscle gutt with the advantages of synthetic fiber gutt. Next, embodiments of the present invention will be described. Example 1 As shown in Figures 1 and 2, carbon fiber multifilament (elastic modulus 18t/mm ² , strength 300Kg/mm ² , elongation 1.7%) 1 is made from 2000 3-denier carbon fibers.
Bundle and nylon multifilament (strength 34Kg/
mm ² , elastic modulus 200 Kg/mm ² ), 3 bundles and 4 bundles were twisted together, and the resulting fibers were passed through a nylon bath and coated with nylon. The diameter of each piece of gutt obtained was 1.4mm, and the various properties of this piece were determined and compared with conventional products, as shown in the table below.

[Table] As is clear from the above table, the products of this example had better properties such as breaking strength and tensile modulus than any of the conventional products. In the table above, it was found that gutt made of 100% carbon fiber has an exceptionally high breaking strength and tensile modulus, and is therefore preferably combined with other fibers. Example 2 A racket made of the product of Example 1 and strings made of nylon thread is strung at 50 pounds (22.50Kg), the racket is set vertically at an angle of 10 degrees, and a tennis ball made of automatic tennis is attached to the racket. Initial speed 100Km/hr from a distance of 10m using a sender
I launched the ball and hit each gut, and conducted a flight distance test 10 times. The results are shown in Table 2.

[Table] As is clear from the above table, the product of this example had a smaller standard deviation than the conventional nylon yarn, and the flight distance was extended by about 8%. Example 3 A tensile test was conducted on the product of Example 1, commercially available sheep intestine guts, and nylon guts, and the elongation (%)-tensile load (Kg) curves for each were determined and the results are shown in FIG. As is clear from Figure 3, the modulus of elasticity of conventional nylon thread products changes significantly when the elongation reaches a certain value, but in this example, the elongation rate remains constant under tensile load. , the growth rate does not change significantly depending on the strength of the ball.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of a gut according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line -' in FIG. Further, FIG. 3 shows the elongation rate (%) vs. tensile load (Kg) curves obtained by conducting a tensile test on the product of this example, commercially available sheep intestine guts, and nylon guts. 1... Carbon fiber multifilament, 2... Nylon multifilament, 3... Nylon layer.

Claims (1)

[Claims] 1 Carbon fiber multifilament, which is a large number of fine carbon fiber filaments bundled in one direction, and nylon multifilament, which is a large number of fine nylon filaments bundled in one direction, are twisted and twisted, and the resulting fibers are covered with nylon resin. Guts for rackets.