JPH0230267B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a racket string. Conventionally, guts used in tennis and badminton rackets have been made by twisting the sinew of animals such as sheep and whales to an appropriate degree and solidifying them with a binding agent to form bristles. In terms of quality, these conventional guttets have moderate strength and elongation characteristics, are highly rigid and highly elastic, and exhibit excellent physical properties such as little loosening during use, and also have a good feel when hitting the ball. It also has excellent batting sound. However, it has the disadvantage of extremely poor water resistance, and in addition, animal muscle guts of this type are also problematic in terms of resources.
Therefore, they are generally expensive. In order to overcome these drawbacks of animal muscle guts, synthetic fiber guts, which are made by appropriately twisting and resin-processing monofilament or multifilament polyamide synthetic fibers, have been developed and are now in widespread use. However, even with gutts made from thermoplastic fibers, although they are superior in water resistance and durability compared to animal muscle guttets, they are inferior in rigidity and elastic modulus, and the threads may loosen during use, causing problems when hitting the ball. Both the feel of the ball and the repulsive force of the ball were not satisfactory. The present invention was made in order to solve these conventional problems, and is a synthetic fiber gutt with excellent water resistance and durability, which also has the advantages of animal muscle gut, which is high rigidity and high elasticity. To provide a racket gut that has the same features and is inexpensive. Therefore, the features of the present invention are as follows:
In the synthetic fiber string made of monofilament and/or multifilament of synthetic fiber, the synthetic fiber string made of monofilament or multifilament or those is zone heat treated by passing through a narrow heating zone of 3 mm or less, 20 kg load, The elongation rate (load state) after one hour at a temperature of 20°C is set to 9% or less, and the tension when the strain rate is 5% is set to 12Kg to 23Kg. Hereinafter, the racket string of the present invention will be explained in detail. The gutt of the present invention is a synthetic fiber gutt, which is made by suitably twisting and resin processing polyamide synthetic fiber monofilament or multifilament, and has an outer diameter of 1.6 mm or less, preferably 1.4 mm or less, The structure itself is not particularly limited. Note that monofilament and multifilament may be used in common. Examples of polyamide synthetic fibers include nylon 6, nylon 6.6, nylon 11, and nylon 12. The monofilament or multifilament, or the synthetic fiber string formed by twisting and resin processing thereof, is subjected to zone stretching and zone heat treatment. The equipment used for this treatment is equipped with three mechanisms: heating the zone, generating tension, and moving the heating furnace or the workpiece. Specifically, the heating furnace is fixed and the workpiece is moved. The fiber is passed through a heating furnace at a constant speed while tension is generated in the fiber by two rolls rotating at different speeds. However, zone heat treatment is characterized by very high tension and movement in a narrow heating zone, and local heating of the object to be treated involves a wide range of sliding of the molecular chains because the object is sandwiched between the solid phase above and below. In addition, the total tension applied concentrates on the softened narrow part and becomes effective in elongating the molecular chain.
Furthermore, the movement of the heating zone enables the formation of an orderly structure sequentially from one end of the object to be treated, giving the object more uniform properties. Zone heat treatment is intended to achieve an irreversible transformation of crystal morphology from lamellae to extended chain crystals starting from one end of the workpiece. In general, synthetic fiber gutt is
As disclosed in Japanese Patent Publication No. 58-39662,
It includes stretching and heat treatment steps. These conventional methods cannot prevent the molecular chains from sliding over a wide range, making it difficult to effectively use the applied tension. However, the above-mentioned zone heat treatment method does not have this problem, and produces a material similar to gutt made from sheep intestine. It can be made into a characteristic gut. Next, the characteristics of the gutt according to the present invention will be clarified through experimental examples (see the attached drawings). For the experimental method, we used a commercially available polyamide synthetic fiber called "Hi-Sheep".
(manufactured by Gosen Co., Ltd.) is fixed with a tension of 10 kg,
This string was passed through a ring-shaped heating furnace with an inner diameter of 4 mm and a thickness of 3 mm, and the heating furnace was set at a furnace speed of 100 mm/min and a furnace temperature of 180°C, and the string was subjected to zone heat treatment for 6 hours.
Repeated times (sample A). Separately, "High Sheep" was fixed with a tension of 5.2 kg and heat treated under the same conditions as above (Sample B). Furthermore, another "High Sheep" was fixed with a tension of 5.2 kg and the zone heat treatment was repeated 12 times (Sample C). In addition, as a comparative product, the conventional synthetic fiber Gatsu "Hi-Sheep"
(Sample E) and sheep intestine gut "Victor Imperial" (manufactured by Victor Sports Inc.) (Sample D) were used. As is clear from the figure, the elongation rate of the conventional synthetic fiber gut (Sample E) is greater than that of the sheep intestine gut (Sample D), which is an animal muscle gut.
The initial elongation due to the load when hitting the ball becomes very large. Therefore, the repulsion force is inferior, the feel at impact is dull, the player is required to use strong hitting force, which causes great fatigue, and moreover, the ball sag during use. Furthermore, the tension (modulus of elasticity) is lower than that of the sheep intestine gutt (sample D), which can be said to be one of the reasons for the poor repulsion and feeling when hitting the ball. However, the synthetic fiber guts of the present invention (samples A, B, and C)
According to the research, the tensile properties were significantly improved, especially when the strain rate was 10%, the synthetic fiber gutt (sample A) had almost the same properties as the sheep intestine gutt (sample D), and the tensile strength (longitudinal elastic modulus) was The tension (longitudinal elastic modulus) of the sheep intestine gut (sample D) was equal to or higher than that of the sheep intestine gutt (sample D). When this synthetic fiber gut (Sample A) was stretched over a racket frame and played, the feel at impact and the flight performance of the ball were close to those of the sheep intestine gut. Note that the tension (longitudinal elastic modulus) of the other samples B and C was also larger than that of sample E. Furthermore, another experimental example will be shown. Inner diameter 5mm, thickness 15
mm ring-shaped heating furnace is fixed and a polyamide-based synthetic fiber gut (tan rope) is applied with a tension of 8 kg.
DTS-2000) was passed through the furnace at a furnace temperature of 190°C at a speed of 200 mm/min. The obtained sample G - that is, the product according to the present invention - and the untreated polyamide synthetic fiber gut (sample F)
(Dunlop DTS-2000) and Victor Imperial (Sample H) were stretched at strain rates of 5% and 10%, respectively, and the respective tensions (Kg) and loads of 20Kg and 25Kg were applied, respectively. Elongation rate after being left at 20℃ for 1 hour (measured under load)
The following table shows the comparison.

〔Effect of the invention〕

As described above, the present invention is characterized in that a monofilament or multifilament or a synthetic fiber string made of them is subjected to zone heat treatment by passing through a narrow heating zone of 3 mm or less, and the elongation rate after 1 hour at a load of 20 kg and a temperature of 20 ° C. (load condition) is set to 9% or less, and the tension when the strain rate is 5% is set to 12Kg to 23Kg, so by applying tension by local heating, the molecular It prevents extensive chain slippage and is effective in elongating molecular chains.
It makes it possible to form an orderly structure, and the guts have uniform quality (strength).Although it is a synthetic fiber gutt, it has high rigidity and elasticity, and has the advantages of animal muscle guts. Furthermore, manufacturing equipment can also be downsized.

[Brief explanation of drawings]

The figure is a tension strain diagram showing the tension characteristics of the string according to the present invention in comparison with a conventional string.

Claims (1)

[Claims] 1. In a synthetic fiber string made of monofilament and/or multifilament synthetic fiber, the monofilament or multifilament, or the synthetic fiber string made of them, passes through a narrow heating zone of 3 mm or less. zone heat treated,
The elongation rate (load state) after 1 hour at a load of 20Kg and a temperature of 20℃ is set to 9% or less,
A racket gutt characterized by having a tension set at 12Kg to 23Kg when the strain rate is 5%.