JP5228296B2 - Gut - Google Patents

Description

  The present invention relates to a gut suitably used for racket applications such as tennis, squash, badminton and the like.

  In recent years, synthetic fiber guts are generally used in place of animal fiber guts (so-called natural guts) in the field of racket sports such as tennis, squash, badminton and the like because of the advantage of being inexpensive and excellent in durability.

  One of the required properties required for synthetic fiber guts is high resilience. In recent years, the speed of ball and shuttle launches has improved dramatically with the improvement of athlete technology. Depending on the player's play style, especially in the field of badminton, high repulsion, so-called good play, is required in order to improve the response from the collision to a shuttle or other gut.

  In the prior art, studies on a gut that satisfies the above-described required characteristics have been studied from various aspects such as a core yarn material, a side yarn material, a covering layer material, and stress-strain characteristics.

Among them, Patent Document 1 describes a technique focusing on stress-strain characteristics as in the present invention. Patent Document 1 discloses that a gut excellent in repulsive force can be obtained by “a racket gut having a tension of 28 to 60 kgf / mm ² when made of a polyamide-based synthetic fiber and having a strain rate of 10%”. It is described. In other words, the technique described in Patent Document 1 focuses on the characteristics of the initial stage of extension before being stretched on the racket, and suggests that a gut having excellent repulsive force can be obtained as the tension at 10% extension is higher. ing.

When the method described in Patent Document 1 is used, a gut that is superior to the repulsive force as compared with a normal gut can be obtained, but there is a problem that it is difficult to stretch the racket because the tension at the initial stage of extension is high. It was.
Japanese Patent Laid-Open No. 62-201166

  An object of the present invention is to provide a gut that is suitable for tennis, squash, and badminton use, has high resilience, and can be easily stretched on a racket.

As a result of repeated studies by the inventors in view of the background of the prior art, the stress-strain curve has an elongation of 11 to 15% when a tension of 29.4 kgf / mm ² is applied, and a tension of 29 Got tension during 2% elongation when a .4kgf / mm ² was zero point, characterized in that a on 8.75kgf / mm ² or more was found to achieve the above-mentioned problem. Further, the gut of the present invention preferably has a tension at 10% elongation of 10 to 26 kgf / mm ² and an elongation at 41.3 kgf / mm ² of 12 to 17% in the stress-strain curve. It is a form.

  The gut of the present invention is a gut having a high repulsive force after the racket is stretched compared to the conventional gut on the racket, and is excellent in feeling of playing, hitting sound, and response at the time of hitting.

  The gut structure of the present invention is not particularly limited, and a commonly known gut structure (for example, core yarn + side yarn + coating layer) can be employed. At this time, the core yarn and / or the side yarn may be impregnated with an adhesive or the like, and the side yarn and the core yarn may be bonded with an adhesive. Moreover, as a form of a core yarn and a side yarn, well-known fibers, such as a multifilament, a monofilament, a spun yarn, and a slit yarn, can be used, but it is preferable to use a multifilament from a viewpoint of manufacturing cost. In addition, in order to adjust the thickness of the gut, the thickness of the fiber to be used and the processing form can be freely changed, or the outer layer of the side yarn may have a layer made of fiber or resin.

  As long as the filament used in the gut of the present invention does not impair the effects of the present invention, specifically, 5% by weight or less based on the total amount of the filament and the additive, different polymers, various light-proofing agents, and pigments are used. Further, additives such as flame retardants, matting agents, lubricants and pigments may be contained. Further, the single yarn cross section of the filament may be an irregular cross section other than the round cross section, and the irregular cross sectional shape may be a flat type, a triangular type, a C type, a Y type, a dumpling type, a hollow type, or a combination thereof. However, the present invention is not limited to this.

  The material used for the core yarn and the side yarn used in the gut of the present invention is not particularly limited, and may be aliphatic and / or aromatic polyester, aliphatic and / or aromatic nylon, polyolefin as long as the present invention is satisfied. Ordinarily known resins such as can be used. However, from the viewpoint of durability, it is preferable to use a polyamide-based resin, particularly nylon 66 excellent in processability, economy, and toughness. By using nylon 66, not only can the gut be produced at a low cost, but a gut having high strength and excellent wear resistance can be obtained by making 95 mol% or more hexamethylene adipamide units.

  When nylon 66 is used, the copolymer component may be contained if it is less than 5 mol%, and when the hexamethylene adipamide unit is less than 95 mol%, the crystallinity in the nylon 66 multifilament is lowered. It becomes difficult to get a high-powered gut. Examples of the copolymer component include ε-capramide, tetramethylene adipamide, hexamethylene sebacamide, hexamethylene isophthalamide, tetramethylene terephthalamide, and xylylene phthalamide.

  Moreover, it is preferable that nylon 66 contains 10-500 ppm of a copper compound as a copper metal amount, and a more preferable range is 50-100 ppm. By making the amount of copper metal within the above range, excellent weather resistance and heat resistance are exhibited in actual use. Examples of the copper compound include copper iodide, copper chloride, copper bromide and the like, but are not limited thereto, and conventionally known inorganic and organic copper salts and simple copper metal can be used. . The nylon 66 filament may contain other heat-resistant agents such as amine compounds, mercapto compounds, phosphorus compounds and hindered phenol compounds in addition to copper compounds. In addition, the measuring method of the amount of copper compounds is not particularly limited, and for example, it may be measured by an EPMA (Electron Probe Micro Analyzer) method using a calibration curve using JXA-8200 manufactured by JEOL.

  The relative viscosity of sulfuric acid of the nylon 66 filament is preferably 3 to 5.5, more preferably 3.5 to 5. When the relative viscosity of sulfuric acid is less than 3, it is impossible to stably obtain nylon 66 filament having the strength required for the gut application used in the present invention. When the relative viscosity of sulfuric acid exceeds 5.5, the viscosity is too high, and it is difficult to obtain nylon 66 filaments with good yarn production.

  The strength of the filament used in the gut of the present invention is preferably 9.5 to 12 cN / dtex. The strength of the filament usually used for the gut is at most 9 cN / dtex. There has never been a racket gut using a filament having a strength exceeding 9.5 cN / dtex, and by arranging a filament of 9.5 cN / dtex or more on the core yarn, the strength per unit cross-sectional area is high and fine. A gut that can be gauged can be obtained. Originally, there is no upper limit on the strength of the filament, but there is an upper limit on the strength at which a filament can be obtained with good productivity by each material. For example, in the case of nylon 66 filament, it is possible to obtain a filament exceeding 12 cN / dtex with good productivity. Have difficulty.

  The breaking elongation of the filament used in the gut of the present invention is preferably 16 to 24%, more preferably 16 to 22%. When the elongation at break is less than 16%, there is a problem that the play portion is small when the gut is stretched on the racket and the actual tension is different from the tension applied during the stretch, or when the gut is stretched on the racket. There is a problem that it is difficult to tie. Further, when the elongation at break exceeds 24%, the vibration at the time of hitting the ball is large, and there is a possibility that the hit feeling is inferior.

  The filament used in the gut of the present invention preferably has a single yarn fineness of 1 to 20 dtex. If the single yarn fineness is less than 1 dtex, the single yarn fineness is too thin, the strength per single yarn is insufficient, and the process passability deteriorates in the gut manufacturing process. Moreover, when the single yarn fineness exceeds 20 dtex, the durability of the gut may be lowered. That is, when the single yarn fineness exceeds 20 dtex, there is a concern that the fatigue property of the gut is deteriorated because the outer stretch and the inner shrinkage of the portion subjected to the bending of each single yarn at the time of hitting are large. The single yarn fineness is preferably in the range of 1 to 15 dtex, more preferably 1 to 10 dtex.

  The total fineness of the filament used in the gut of the present invention is preferably 420 to 3600 dtex. When the total fineness is less than 420 dtex, the productivity at the time of filament production is poor and the cost increases, and when the total fineness exceeds 3600 dtex, it is difficult to obtain a filament with good yarn production.

  The degree of amorphous molecular orientation (fa) when N66 filament is used as the filament used for gut is preferably 0.72 to 0.9. The degree of amorphous molecular orientation (fa) indicates the orientation of tie molecules linking crystal molecules in the nylon 66 filament, and when nylon 66 filament having an amorphous molecular orientation degree (fa) of less than 0.7 is used for the gut. Since the orientation of tie molecules in nylon 66 filament is poor, it is difficult to obtain a high strength gut. In addition, it is difficult to obtain nylon 66 filaments with an amorphous molecular orientation altitude exceeding 0.9 with good spinning properties.

The degree of amorphous molecular orientation (fa) is determined by birefringence, crystallinity obtained from density, and crystal orientation. S. Stein et al. Polymer Sci. , 21, 381, (1956).
Δ = XfcΔ ⁰ c + (1−X) faΔ ⁰ a
Here, Δ = birefringence, X: crystallinity, fc: crystal orientation, fa: amorphous molecular orientation, Δ ⁰ c: intrinsic birefringence of crystal part, Δ ⁰ a: intrinsic birefringence of amorphous part , (Δ ⁰ c = Δ ⁰ a = 0.73)
The birefringence is measured by a Belek compensator method using a POH polarization microscope manufactured by Nippon Kogyo Kogyo Co., Ltd., and the density is measured by a density gradient tube method using toluene as a light liquid and carbon tetrachloride as a heavy liquid. It can be measured at ° C. The crystallinity may be calculated using the following formula.
Crystallinity (X) = {dc (d-da)} / {d (dc-da)}
At this time, dc represents the crystal density, da represents the amorphous density, and d represents the density of the sample.

Further, the degree of crystal orientation (fc) was measured using an X-ray generator (4036A2 type) manufactured by Rigaku Denki Co., Ltd. using CuKα (using a Ni filter) as a radiation source (output 35 KV, 15 mA, slit 2 mmφ). What is necessary is just to obtain | require using the following formula | equation from the half value width H ° of the intensity distribution obtained by scanning the (100) plane observed in the vicinity of 2Θ = 20.6 ° in the circumferential direction.
fc = (180 ° −H °) / 180 °
The gut of the present invention is not particularly limited in the coating resin used. Natural resins may be used as well as synthetic resins such as polyamide, polyester, polyurethane, etc., and they may contain additives such as different polymers, various light-proofing agents, pigments, matting agents, lubricants, pigments, etc. .

  The present invention does not lose its effect due to the gut diameter, and the thickness may be appropriately changed according to the application.

  When using a multifilament for the gut core yarn of the present invention, the core yarn is preferably twisted. By twisting, the convergence of the multifilament is improved and the process passability is stabilized. The number of twists is not particularly limited as long as it does not impair the scope of the present invention, and examples thereof include a range of 10 to 1000 T / m.

  An example of a method for producing a gut filament is shown below by taking nylon 66 multifilament as an example, but the production method is not limited to this.

  Nylon 66 multifilament is obtained by cooling and solidifying melt-spun yarns, applying an oil agent, and drawing the yarns between rollers. In order to obtain high-strength fibers, it is preferable to employ a multi-stage stretching method of 3 to 5 stages. The following description will be made by a three-stage stretching method.

  The water content of the polymer used for melt spinning is preferably 0 to 200 ppm. The moisture content may be measured by a generally known method. For example, it can be measured by a coulometric titration method using a Karl Fischer moisture meter (AQ-2100) manufactured by Hiranuma Sangyo Co., Ltd.

  The spinning temperature can be changed depending on the presence or absence of a copolymer component, but is usually set to 250 to 300 ° C.

  Immediately below the spinneret, the upper end is 0 to 15 cm from the spinneret surface, and a range of 5 to 100 cm from the upper end is surrounded by a heating tube and / or a heat insulating tube, and the spinning yarn is placed in a high temperature atmosphere of 200 to 280 ° C. Passing through is a preferred form. The orientation of the spun yarn is relaxed by slow cooling through the high temperature atmosphere surrounded by the heating tube and / or the heat insulation tube without immediately cooling the spun yarn, and the molecular orientation between the single fibers Since the uniformity can be improved, it is possible to increase the strength of the nylon 66 multifilament. On the other hand, if it cools immediately without letting it pass in a high temperature atmosphere, the orientation of an undrawn yarn will increase and the orientation degree distribution between single fibers will become large. When such an unstretched yarn is heat-drawn, there is a possibility that a nylon 66 multifilament having high strength and excellent heat resistance may not be obtained as a result.

  The unstretched yarn that has passed through the high-temperature atmosphere is then preferably cooled and solidified by blowing air at 10 to 100 ° C., preferably 10 to 75 ° C. When the cooling air is less than 10 ° C., a large cooling device is required separately from the normal device, which is not preferable. In addition, when the cooling air exceeds 100 ° C., the single fiber sway during spinning becomes large, so that the single fibers collide with each other, making it difficult to produce the fibers with good spinning properties. The air cooling device may be a horizontal blowing type or an annular blowing type.

  The oil agent is then applied to the cooled and solidified unstretched yarn. The oil agent is preferably a non-aqueous oil agent containing a smoothing agent as a main component and containing a surfactant, an antistatic agent, an extreme pressure agent component and the like.

  The unstretched yarn to which the oil is applied is wound around a take-up roller (1FR) and taken up. The surface speed of 1FR, that is, the take-up speed is preferably 300 m / min or more, more preferably 500 m / min or more. If the take-up speed is less than 300 m / min, the production efficiency is low and it is difficult to adopt. Although there is no particular upper limit to the take-up speed, the take-up speed is preferably 2000 m / min or less for industrially stable production.

  The undrawn yarn taken up at the take-up speed is drawn once or continuously without being taken up. A Nelson type roller having two rollers as one unit includes a yarn feeding roller (2FR), a first stretching roller (1DR), a second stretching roller (2DR), a third stretching roller (3DR), and a relaxation roller (RR). ) Are arranged side by side, and the yarn is sequentially wound to perform a drawing heat treatment. Usually, stretching is performed between 1FR and 2FR to focus the yarn. A preferred stretch ratio is in the range of 1 to 7%, more preferably 1 to 5%. The yarn subjected to the drawing heat treatment is wound up by a winder.

  Stretching is performed between 2FR and 1DR, between 1DR and 2DR, and between 2DR and 3DR. At this time, in the stretching between 2FR and 1DR, it is preferable that the draw point, that is, the point at which the yarn is sharply reduced by stretching does not exist on 2FR. The draw point is more preferably within 10 cm from the 2FR exit. By setting the position of the draw point within the above range, it is possible to obtain a high-strength nylon 66 multifilament. The position of the draw point can be adjusted by changing the draw ratio, roller temperature, and roller surface friction according to the degree of orientation of the fiber.

  The draw point may be determined by measuring the yarn speed from 2FR to 1DR using a laser Doppler velocimeter (LS-50M manufactured by TSI), and setting the draw point as the point where the speed suddenly increases to near the 1DR surface speed. .

  The first stage stretching is performed between 2FR and 1DR, the 2FR temperature is 30 to 80 ° C, the 1DR temperature is 80 to 150 ° C, and the first stage stretching ratio is preferably 20 to 90% of the total stretching ratio. Furthermore, it is more preferable to set it to 20 to 50%.

  The second stage stretching is performed between 1DR and 2DR, but the 2DR temperature is 180 to 240 ° C., and the second stage stretching ratio is preferably 20 to 40% of the total stretching ratio, and more preferably 20 to 30%. preferable.

  The third stage stretching is performed between 2DR and 3DR. The temperature of 3DR is 180 to 250 ° C., and stretching is performed so that the target total stretching ratio is obtained at the third stage stretching ratio.

  The finished yarn is subjected to a relaxation treatment of 0 to 5% between 3DR and RR, and then wound up by a winder. By the relaxation treatment, not only the strain caused by the thermal stretching can be removed, but also the highly oriented structure achieved by the stretching can be fixed, the orientation of the amorphous region can be relaxed and the thermal shrinkage rate can be lowered. RR uses a non-heated roller or a roller heated to 160 ° C. or less. Usually, RR becomes a temperature of 90 to 150 ° C. regardless of the presence or absence of heating due to the heat brought in by the yarn heated at the time of hot drawing.

  Thus, the filament used for the gut of the present invention can be obtained.

In the gut of the present invention, in the stress-strain curve, it is essential that the tension at 2% elongation when the tension is 29.4 kgf / mm ² is zero point is 8.75 kgf / mm ² or more, preferably 9 0.5 kgf / mm ² or more. This requirement is the most different point between the prior art and the present invention.

The gut is tensioned to the racket with a constant tension (for example, 25-40 pounds for badminton gut). The tension of 29.4 kgf / mm ^{2 of} the present invention corresponds to the tension that the gut receives after being stretched on the racket. In the stress-strain curve, the gut of the present invention in which the stress at 2% elongation when the tension is 29.4 kgf / mm ² is zero point or more is 8.75 kgf / mm ² or more has a modulus after being stretched on the racket. high order, good stress at 2% elongation as compared with conventional gut less than 8.75kgf / mm ² repulsive force when the tension 29.4kgf / mm ² was zero, the result as a ball or, , The ball leaving when you hit the shuttle is fast, enabling speedy competition. In conventional gut development, there was no technology that focused on gut behavior (modulus) after racket tensioning.

There is no particular upper limit to the stress at 2% elongation when the tension is 29.4 kgf / mm ² , but considering the ease of tensioning the racket and the burden on the elbow during competition, 26.5 kgf / Mm ² or less is preferable, and 13.3 kgf / mm ² or less is more preferable.

The gut of the present invention preferably has a tension at 10% elongation of 10 to 26 kgf / mm ² . Further preferred examples of the tension at 10% elongation include 14 to 22 kgf / mm ² . If the tension at 10% elongation is less than 10 kgf / mm ² , the tension is too low and it may be difficult to stretch the racket. On the other hand, when the tension at 10% extension exceeds 26 kgf / mm ² , the tension at the initial stage of the extension is strong and the elbow is damaged greatly. It may be difficult to set up. That is, the technique of the present invention, unlike the technique described in Patent Document 1, has ease of tensioning on the racket and resilience that satisfies the player's requirements.

Gut of the present invention is Ru elongation 11-15% der at the time of application of a tension of 29.4kgf / mm ^2. When 29.4 kgf / mm ² tension is applied, that is, when the elongation under a tension of a general racket is less than 11%, the workability may be deteriorated because the elongation of the gut at the time of tension is small. There is. In addition, if the elongation at the time of applying a tension of 29.4 kgf / mm ² exceeds 15%, it is excessively stretched when it is stretched to the racket. There is a possibility of becoming thinner than the diameter.

In the stress-strain curve of the gut of the present invention, the elongation at 41.3 kgf / mm ² tension is preferably 12 to 17%, and more preferably 13 to 16%. In a stress-strain curve where the elongation at 41.3 kgf / mm ² tension exceeds 17%, the stress at 2% elongation when the tension is 29.4 kgf / mm ² is outside the scope of the present invention. Not only is there a possibility, but there is a possibility that it will be difficult to stretch the gut due to excessive elongation. On the other hand, a gut of less than 12% may be difficult to stretch on a racket because of its small elongation.

  The gut of the present invention has been found as a result of various studies on gut characteristics by the present inventors, and by setting the gut characteristics to a specific range, it has not been possible to achieve high performance. The idea is completely different from the prior art that achieved the repulsion effect.

  Next, a badminton gut is illustrated as an example of the method for producing a racket gut according to the present invention, but the method for producing a racket gut is not limited thereto.

  The nylon 66 multifilament obtained by the above method is twisted to obtain a core yarn. At this time, the number of nylon 66 multifilaments used may be adjusted so that the fineness required for the core yarn is obtained, and twisting may be performed while combining the yarns as necessary. At this time, the core yarn may be impregnated with an adhesive or the like, but it is preferable not to impregnate the core yarn with an adhesive or the like in order to improve the durability of the gut.

  Side threads are arranged on the obtained core yarn, and a resin coating is applied. When arranging the side yarn on the core yarn, the side yarn can be fixed with an adhesive as necessary. The side yarn to be used is not limited, and a plurality of types of fibers may be used, and the side yarn to be used may be arranged in a plurality of layers according to the thickness of the gut required. . As a method for arranging the side yarns, a known method such as braiding or winding can be employed. Examples of the resin coating method include a dipping method and a melt coating method.

  The gut having the characteristics of the present invention can be obtained by controlling the temperature and tension at the time of heat setting applied in a state where tension is applied after resin coating, and by applying relaxation treatment after heat setting. Specifically, except for special cases, the heat setting conditions that are usually adopted at present are a temperature of 150 to 190 ° C. and a stretching ratio between rollers of 0 to 15%. And a relaxation treatment, a gut having the characteristics of the present invention can be obtained. The heat setting temperature at this time is preferably a melting point of the filament of −50 ° C. to a melting point of the filament of −10 ° C. Further, the stretching ratio between the rollers is preferably 10 to 30%, and more preferably 15 to 30. In the relaxation treatment, the relaxation rate is preferably 0.5% to 10%, and the temperature is more preferably a melting point of the filament of −50 ° C. to a melting point of the filament of −10 ° C. In addition, when a filament having the strength currently used in ordinary gut is applied to the core yarn, the fiber may be deteriorated or broken at the time of high-temperature high-tensile heat setting. Therefore, 9.5 cN / dtex as described above is set. It is preferable to use a filament exceeding that, particularly nylon 66 filament excellent in toughness.

  Thus, the gut of the present invention can be obtained.

  Hereinafter, embodiments of the present invention will be described in more detail by way of examples. The definition and measurement method of the characteristics used in the specification text and examples are as follows.

  [Sulfuric acid relative viscosity]: 1 g of a sample was dissolved in 100 ml of 98% sulfuric acid, and measured with an Ostwald viscometer at 25 ° C. The average value of the number of executions 2 times was used.

  [Total Fineness]: Measured using a JIS L1013A method with a predetermined load of 5 mN / tex and a yarn length of 90 m. Moreover, the value which divided the total fineness by the number of single fibers which comprised was used for the single yarn fineness.

  [Fiber strength and elongation]: Measured by the method of JIS L1013. Using a Tensilon tensile tester manufactured by Orientec Co., Ltd., measurement was performed under the conditions of a test length of 250 mm and a tensile speed of 300 mm / min. Each sample was measured 5 times, and the average value was obtained.

[Amorphous molecular orientation]:
The degree of amorphous molecular orientation (fa) is determined by birefringence, crystallinity obtained from density, and crystal orientation. S. Stein et al. Polymer Sci. , 21, 381, (1956), and an average value of two measurements was obtained.
Δ = XfcΔ ⁰ c + (1−X) faΔ ⁰ a
Here, Δ = birefringence, X: crystallinity, fc: crystal orientation, fa: amorphous molecular orientation, Δ ⁰ c: intrinsic birefringence of crystal part, Δ ⁰ a: intrinsic birefringence of amorphous part , (Δ ⁰ c = Δ ⁰ a = 0.73)
For the birefringence, the average value of three trials obtained by measuring by the Belek Compensator method using a POH polarization microscope manufactured by Nihon Kogyo Kogyo Co., Ltd. was used.

  For the density, an average value of three trials obtained by measuring at 25 ° C. by a density gradient tube method using toluene as a light liquid and carbon tetrachloride as a heavy liquid was used.

The crystallinity was calculated using the following formula.
Crystallinity (X) = {dc (d-da)} / {d (dc-da)}
At this time, dc is the crystal density (= 1.24 g / cm ³ ), da is the amorphous density (= 1.09 g / cm ³ ), and d is the density of the sample.

The degree of crystal orientation (fc) was measured using an X-ray generator (4036A2 type) manufactured by Rigaku Corporation with CuKα (using a Ni filter) as a radiation source (output 35 KV, 15 mA, slit 2 mmφ). What is necessary is just to obtain | require using the following formula | equation from the half value width H ° of the intensity distribution obtained by scanning the (100) plane observed in the vicinity of 2Θ = 20.6 ° in the circumferential direction.
fc = (180 ° −H °) / 180 °

[Linear strength of monofilament]:
It measured by the method of JIS L1013. Using a Tensilon tensile tester manufactured by Orientec Co., Ltd., measurement was performed under the conditions of a test length of 250 mm and a tensile speed of 300 mm / min. Each sample was measured 5 times, and the average value was obtained.

[Gut productivity]: Evaluated in two stages from the situation of continuous production.
A: Stable production for a long time is possible. 0.05 times / less than 10,000 m ○: Some yarn breakage occurred. 0.05-0.5 times / 10,000m.
Δ: Many yarn breaks. It exceeds 0.5 times / 10,000m.

[Gut strength]: Measured using a Tensilon tensile tester manufactured by Orientec Co., Ltd. under conditions of a test length of 250 mm and a tensile speed of 300 mm / min. Further, from the stress-strain curve curve obtained at that time, the tension at the time of 2% extension when the tension of 29.4 kgf / mm ² was taken as the zero point was obtained. Each sample was measured 5 times, and the average value was obtained.

[Gut elongation]: Using a Tensilon tensile tester manufactured by Orientec, draw a stress-strain curve under the conditions of a test length of 250 mm and a tensile speed of 300 mm / min, and give a tension of 29.4 kgf / mm ² from the curve. The elongation at the time of 41.3 kgf / mm ² hours was calculated | required. Each sample was measured 5 times, and the average value was obtained.

[Monitor test]: In an actual hit test by an athlete with 11 years of competition experience, a one-hour hit test was conducted using a racket (NS7000 manufactured by Yonex Co., Ltd.) with a gut stretched at a tension of 25 pounds. . The repulsive force and feel at impact when using the gut of Comparative Example 1 that is close to a normal sales product was evaluated as 5 points as follows.
5: Particularly excellent, 4: Excellent, 3: Normal, 2: Inferior, 1: Particularly inferior

(Production example)
[Manufacture of filament A]
An 80% aqueous solution of hexamethylene diammonium adipate was placed in a polymerization vessel, polymerized by heating to 300 ° C., and the polymerization time was adjusted so that the relative viscosity was 3.9. The obtained polymer was pelletized to obtain nylon 66 pellets having a diameter of 2.5 mm and a length of 4.0 mm. The obtained nylon 66 pellets were melt-spun at 280 ° C. using an extruder-type spinning machine. The molten polymer was weighed with a gear pump so as to have a fineness of 1050 dtex, filtered through a 20 μm metal nonwoven fabric filter in a spinning pack, and spun from a 210-hole die with a hole diameter of 0.3φ. A 15 cm heating cylinder and a 15 cm heat insulation cylinder were attached 3 cm below the base surface, and heated so that the in-cylinder atmosphere temperature was 250 ° C. Here, the in-cylinder atmosphere temperature is an air layer temperature in a central portion of the heating cylinder length and a portion 1 cm away from the inner wall.

  An annular blow-off chimney was attached immediately below the heating cylinder, and cold air of 30 ° C. was blown onto the yarn at a rate of 35 m / min to cool and solidify, and then an oil agent was applied to the yarn.

  After two unstretched yarns to which an oil agent was applied were combined, the yarn was wound around 1FR rotating at a surface speed of 370 m / min, and then stretched at 5.95 times. The take-up yarn was continuously wound without being wound once, and stretched at a stretch rate of 5% between the take-up roller and 2FR, followed by three-stage heat drawing, and wound at a speed of 2200 m / min. 1FR was unheated, 2FR was 60 ° C, 1DR was 115 ° C, 2DR was 200 ° C, 3DR was 210 ° C, and RR was unheated. The number of times the yarn was wound around the roller was 3, 4, 4, 4, 5, and 4, respectively. An entanglement nozzle was installed between the RR and the winder to entangle the fibers. The entanglement is performed by injecting high pressure air of 2 kg / cm 2 in a direction substantially perpendicular to the running yarn in the entanglement applying device to obtain nylon 66 multifilament, and the first stage draw ratio is 40% of the total draw ratio. The second stage stretch ratio was set to 35%, and the third stage stretch ratio was set to 25%. The physical properties of the obtained fiber were a fineness of 2100 dtex, a strength of 9.8 cN / dtex, an elongation of 20%, and an amorphous orientation of 0.79.

[Manufacture of filament B]
An 80% aqueous solution of hexamethylene diammonium adipate was placed in a polymerization vessel, polymerized by heating to 300 ° C., and the polymerization time was adjusted so that the relative viscosity was 3.9. The obtained polymer was pelletized to obtain nylon 66 pellets having a diameter of 2.5 mm and a length of 4.0 mm. The obtained nylon 66 pellets were melt-spun at 280 ° C. using an extruder-type spinning machine. The molten polymer was weighed with a gear pump so as to have a fineness of 1050 dtex, filtered through a 20 μm metal nonwoven fabric filter in a spinning pack, and spun from a 210-hole die with a hole diameter of 0.3φ. A 15 cm heating cylinder and a 15 cm heat insulation cylinder were attached 3 cm below the base surface, and heated so that the in-cylinder atmosphere temperature was 250 ° C. Here, the in-cylinder atmosphere temperature is an air layer temperature in a central portion of the heating cylinder length and a portion 1 cm away from the inner wall.

  An annular blow-off chimney was attached immediately below the heating cylinder, and cold air of 30 ° C. was blown onto the yarn at a rate of 35 m / min to cool and solidify, and then an oil agent was applied to the yarn.

  After two unstretched yarns to which an oil agent was applied were combined, the yarn was wound around 1FR rotating at a surface speed of 370 m / min, and then stretched by 5.50 times. The take-up yarn was continuously wound without being wound once, and stretched at a stretch rate of 5% between the take-up roller and 2FR, followed by three-stage heat drawing, and wound at a speed of 2200 m / min. 1FR was unheated, 2FR was 60 ° C, 1DR was 115 ° C, 2DR was 200 ° C, 3DR was 210 ° C, and RR was unheated. The number of times the yarn was wound around the roller was 3, 4, 4, 4, 5, and 4, respectively. An entanglement nozzle was installed between the RR and the winder to entangle the fibers. The entanglement is performed by injecting high pressure air of 2 kg / cm 2 in a direction substantially perpendicular to the running yarn in the entanglement applying device to obtain nylon 66 multifilament, and the first stage draw ratio is 40% of the total draw ratio. The second stage stretch ratio was set to 35%, and the third stage stretch ratio was set to 25%. The physical properties of the obtained fiber were a fineness of 2100 dtex, a strength of 9.0 cN / dtex, an elongation of 22%, and an amorphous orientation of 0.70.

[Manufacture of filament C]
An 80% aqueous solution of hexamethylene diammonium adipate was placed in a polymerization vessel, polymerized by heating to 300 ° C., and the polymerization time was adjusted so that the relative viscosity was 3.5. The obtained polymer was pelletized to obtain nylon 66 pellets having a diameter of 2.5 mm and a length of 4.0 mm. The obtained nylon 66 pellets were melt-spun at 280 ° C. with an extruder-type spinning machine. The molten polymer was weighed by a gear pump, and the spun yarn melt-extruded from a nozzle having a discharge hole diameter of 0.25 mm was immediately introduced into a 75 ° C. cooling water bath. The unstretched yarn after cooling is taken up at 40 m / min, and then steam-stretched 5.5 times between rollers without being wound once, and nylon 66 monofilament with an average wire diameter of 60 μm is wound at a spinning speed of 200 m / min. I took it. The linear strength of the obtained monofilament was 2.3N.

(Examples 1-4, Comparative Examples 1 and 2)
The core yarn obtained by twisting the filaments shown in Table 1 at 100 T / m was wound with 16 filaments as a side yarn and spirally wound, and a phenolic adhesive solution (Amilan T-100L (Toray Industries, Inc.) (Made by Co., Ltd.): phenol: xylene = 15 wt%: 80 wt%: 5 wt%) Amylan T-100L (manufactured by Toray Industries, Inc.) melted at 220 ° C. after being heated and dried at 70 ° C., fixed, and melt-dip method And coated. The gut after resin solidification was heat-set in a 230 ° C dry heat furnace installed between rollers rotating at the speed difference shown in Table 1, and then 1% relaxation treatment was performed in the 230 ° C dry heat furnace. A gut having a diameter of 0.7 mm was obtained. The physical properties of the obtained gut were evaluated and shown in Table 1.

  As is clear from Table 1, the gut of the present invention is a gut that is very excellent in repulsive force as compared with a gut having the normal physical properties described in the comparative examples.

Claims (3)

In the stress-strain curve, the elongation when applying a tension of 29.4 kgf / mm ² is 11 to 15%, and the tension when the tension is 2% when the tension is 29.4 kgf / mm ² is zero. gut, which is a 8.75kgf / mm ² or more on. The gut according to claim 1, wherein a tension at 10% elongation is 10 to 26 kgf / mm ² . The gut according to claim 1 or 2, wherein an elongation at 41.3 kgf / mm ² is 12 to 17% in a stress-strain curve.