JPH0822320B2 - Gatt for racket and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a racket gut and a method for manufacturing the same.

[Conventional technology and its problems]

Conventionally, the gut used for rackets for tennis and badminton has been obtained by applying a proper twist to animal muscles of sheep, whales, etc. and fixing it with a sizing agent to form bristles. Such a conventional gut has high rigidity and is extremely rich in elasticity, exhibits excellent physical properties such as little slack during use, and is also excellent in feel at hitting and hitting sound. However, it has a drawback that it is extremely weak in water resistance, its tension and strength are remarkably lowered in rainy weather, and that the animal muscle is generally effective.

Therefore, in order to eliminate such drawbacks of animal muscle gut, a twisted monofilament or multifilament is appropriately twisted, and a synthetic fiber gut obtained by resin processing is developed.
I've done my best. The synthetic fiber gut has a polyamide type and a non-polyamide type, and the former is composed of nylon 6, nylon 66 and a copolymer fiber thereof, and is superior in water resistance and durability to animal muscle gut, The rigidity and elastic modulus are inferior, the yarn is loosened during use, and the feel at the time of hitting the ball and the resilience of the ball are insufficient. For the latter, polyetheretherketone (Japanese Patent Laid-Open No.
60-21073), polyvinylidene fluoride (JP-A-57-8)
9611) and polyacetal (JP-A-60-279514).
However, all of them have high rigidity, but have a drawback of poor repulsion.

Further, recently, a thin metal wire is spirally wound around a polyamide-based monofilament, and the thin metal wire is covered with a synthetic fiber (Japanese Utility Model Publication No. 52-15301). Carbon fiber is used instead of the thin metal wire. A so-called composite gut, such as one in which a polyamide fiber and an aramid fiber are combined (JP-A-59-64073), has been developed.
Even in these cases, the rigidity is high, but the degree of stretching is small and the resilience is poor, so that there is a problem in that the feel at the time of hitting the ball is poor and the ball does not fly.

〔Purpose〕

The present invention solves these conventional problems, and provides a racket gut that has excellent water resistance and durability, high rigidity, and is highly elastic, and such high performance,
The purpose of the present invention is to easily and inexpensively produce a high quality racket gut.

[Means for Solving the Present Invention]

The racket gut according to the present invention is a racket gut made of a polyamide-based synthetic fiber, and has a strain rate τ.
Tension S in the case of 10% is set to ^{28kg / mm 2 ~60kg / mm 2} . Further, the method for producing a gut according to the present invention is such that the heating temperature T (unit: ° C) is 150 to 200 ° C while applying a tension of 5 to 17 kg / mm ² or stretching by a strain rate of 8 to 20%. Under the above conditions, the heating time (x) (unit: minutes) is set as x ≧ exp {(1300 / T) −6.5}.

[Action]

According to the structure of the above racket gut, the strain rate is 10%.
28kg / mm ^{2 to} 60kg, which is the optimum value for actual use
Since the racket gut is set to / mm ² , the racket gut is highly elastic, has excellent durability, and has excellent repulsion. Further, according to the method for producing the gut, the heat-stretched polyamide-based synthetic fiber is stretched by applying a predetermined high tension at a temperature near the melting point of the crystal, so that the crystal having a folded structure is partially formed. When the fibers are loosened, the fibers are reassembled, the melting point of the crystals is increased, and the heat resistance is improved. further,
By performing these predetermined heat treatments, the degree of orientation of the amorphous chain segments increases, the mechanical dispersion due to the micro Brownian motion of the segments shifts to the high temperature side, and synthetic fibers with low energy loss are produced. It

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

Fig. 2 shows an outer diameter of 1.1 mm used for racket gut
It is an example of a well-known synthetic fiber of ~ 1.4 mm,
[I] and [II] are a core wire 1 made of a polyamide-based synthetic fiber, and a large number of windings 2 of a heat-resistant synthetic fiber containing a polyamide-based synthetic fiber that also covers the core wire 1 by twisting and resin processing. And [III] is a multifilament 3 made of polyamide synthetic fiber formed by twisting and resin processing.

In the racket gut of the present invention, the synthetic fiber is heated and drawn under predetermined processing conditions, and although not shown, a monofilament of synthetic fiber mainly containing polyamide is used as a core wire and / or winding. It is also free to use it for wire and subject the constructed synthetic fiber gut to heat drawing processing.

Therefore, the above processing conditions are determined by the heating temperature, the heating time, and the tension of the synthetic fiber at the time of heating, and these conditions are set to values at which desired elasticity, durability, etc. can be achieved. That is, with respect to the heating temperature, if the heating temperature is too low, the treatment effect is small and the intended purpose cannot be achieved. Regarding the tension, when the tension is too low, it is difficult to obtain a highly elastic synthetic fiber, and when the tension is too high, the synthetic fiber may be cut, and the desired processing conditions are determined in consideration of these points. Specifically, the tension W of the synthetic fiber before processing is 5.0 kg / mm ^{2 to} 17 kg / mm ² . (Preferably ^{10kg / mm 2 ~15kg / mm 2} ), or stretch ratio ψ is 8% of the fibers
The heating temperature T is set to 20% (preferably 13% to 18%) and the heating temperature T is set to 150 ° C to 200 ° C (preferably 165 ° C to 190 ° C).

Further, the heating time x is expressed and determined as a function of the heating temperature T as shown in the following equation (i).

x = exp {(1300 / T) -6.5} (i) Therefore, when the heating temperature T is low, the heating time x requires a long time. The formula (i) shows the minimum time required for heating, and it is free to set the time longer than this. Further, the unit is such that the heating temperature T is “° C.” and the heating time x is “minute”. Then, the polyamide-based synthetic fiber heat-drawn under such processing conditions,
Since a predetermined high tension is applied and stretched at a temperature near the melting point of the crystal, the crystal having a folded structure is partially loosened, the fibers are reassembled, the melting point of the crystal is increased, and the heat resistance is improved. improves. Further, by performing these predetermined heat treatments, the orientation degree of the amorphous chain segment increases, the mechanical dispersion due to the micro Brownian motion of the segment shifts to the high temperature side, and synthetic fibers with small energy loss are obtained. Produced.

Therefore, the synthetic fiber is a product having high elasticity, excellent durability and excellent repulsion, and is optimal as a gut for a racket.

Next, the manufacturing method and characteristics of the gut of the present invention will be described in detail.

Generally, in the conventional method, untreated synthetic fibers are stretch-heated by subjecting them to zone stretching and zone heat treatment. In this method, however, the tension W during processing is small and the heating time x is short. High elasticity cannot be dealt with.

Therefore, in the present invention, the heat drawing process is performed by the method as described below. In the method below,
As the synthetic fiber before processing, a commercially available synthetic fiber that has been subjected to the zone stretching and zone heat treatment described above is used, and its characteristic is that the tension S when the strain rate τ is stretched at 10% is 14.0 to 27.0.
kg / mm ^2, the tensile strength is of 60~70kg / mm ^2.

In FIG. 3, 5 is a gut manufacturing apparatus of the present invention, which is a heating furnace 5 for heating the synthetic fibers 4, and the heating furnace 5.
And a pair of left and right sheaves 7, 7 which are disposed outside both ends of the synthetic fiber 4 and are engaged with the synthetic fiber 4, and a pair of left and right weights 8, 8 suspended by the synthetic fiber 4.

Thus, synthetic fibers 4, which is set at a predetermined position, predetermined load W is multiplied by the weight 8,8 always constant tension W'- i.e. ^{5kg / mm 2 ~17kg / mm 2} - is applied, Then, it is heated at 150 to 200 ° C. for a predetermined time and stretched. Table 1 exemplifies the processing conditions of the gut manufactured by the manufacturing apparatus, and Table 2 shows the tensile strength characteristics of the gut manufactured by the processing conditions of Table 1 as a commercially available conventional product (Dunlop DTS- 2000) and the strain rate τ was 5% and 10%.
The tension S when stretched in%, is shown along with other data. In Table 1, samples A to F use nylon monofilament, and sample G uses Dunlop DTS-20.
00 is used. The water content of the sample after heating is about 0.3%.

Then, as shown in Table 1, the tension W is 5.4 kg / mm.
It is set to ^{2 ~13kg} / mm ^2, a predetermined condition (5.0kg / mm ² ~17kg
/ mm ² ), the heating temperature T is set to 173 degrees, and the heating time x is calculated by the formula (i).
It is heated for a heating time of ≈ 2 minutes or more.

In addition, the tensile strength properties in Table 2 were measured according to JIS-L1070, and the tensile force S when stretched at a strain rate τ of 10% was significantly increased to 43.0 kg / mm. ^{2 to} 58.4 kg / m
It can be seen that the m ² ) breaking strength (kg) also increases about 1.3 times.
Further, FIG. 1 is a plot of the relationship between the strain rate ° C and the tension S in Table 2. From this figure, the tension W during processing is 10
It was found that it is preferably kg / mm ² or more, and it is also found that the heating time x is preferably longer.

Next, a stress relaxation test and an energy loss test were conducted using the sample B in Table 1 as a representative example in order to confirm the repulsive force characteristics in comparison with the conventional product.

Specifically, the stress relaxation experiment is to apply an initial tension of 25 kg / mm ^{2 to} the present gut and the conventional gut in a tensile tester,
The stretching rate was kept the same, and the retention rate after 1 hour was measured.

Further, the energy loss test, in a tensile tester, the present gut and the conventional gut are stretched at a speed of 200 m / min, respectively, and a tension of 30 kg / mm ² or 40 kg / mm ² is applied, and the stress at the time of stretching and The stress at the time of return is measured, and then the total energy given to the measured object and the energy lost due to internal heat generation of the measured object at the time of return are calculated, and the latter is divided by the former to calculate the energy loss. . Third result of stress relaxation test
The results of the energy loss test are shown in Table 4 and Table 4 respectively.

From these results, it was confirmed that the gut of the present invention has a smaller stress relaxation and a smaller energy loss than the gut of the conventional product, and it is proved that the gut of the present invention is rich in repulsive force.

 Further, another manufacturing method will be described in detail.

In FIG. 4, reference numeral 5 denotes another manufacturing apparatus, which is provided with a heating furnace 6 through which the synthetic fiber 4 is heated and passes through, and is disposed outside both ends of the heating furnace 6 and rotates in the direction of arrow M. , And an appropriate number of rollers 9 for continuously feeding and winding the synthetic fiber 4 in the arrow N direction.

Then, the synthetic fiber 4 is set at a predetermined position, and the rotation speed of the winding-side rollers 9 and 9 is set to the delivery-side rollers 9 and 9.
The desired gut is obtained by passing through the heating furnace 6 set to a predetermined heating condition while always maintaining a constant stretching ratio ψ, which is set to be higher than the rotation speed of No.

Table 5 illustrates the processing conditions of the gut manufactured by the manufacturing apparatus, and Table 6 shows the tensile strength characteristics of the gut manufactured under the processing conditions of Table 5 in comparison with the commercially available conventional product. It was made clear.

Then, in Table 5, samples H to J use nylon monofilaments, and sample K uses Dunlop DTS-2000.
Is heated and stretched.

Furthermore, the tension of the synthetic fiber 4 at the time of delivery was set to 2.3 kg / mm ² , and the drawing rate 4 was set to 10% and 15%, and the heating time x was calculated by the formula (i). The calculated heating time x is set to a time of 2 minutes or more.

Further, in Table 6, the commercially available conventional gut b to d are compared using Dunlop DTS-2000, Gohsen Audiogee Sheep Micro, and Nylon Monofilament, respectively. By subjecting the above-mentioned heat stretching treatment from these results,
It has been proved that both the elastic force and the breaking strength are greatly improved. Furthermore, FIG. 5 shows the strain rate τ and the tension S in Table 6.
It is a plot of the relationship with. From this figure, it is found that it is preferable that the stretching ratio ψ of the processing conditions is large.
In the manufacturing apparatus 5, the tension W may be constant instead of the constant stretching ratio ψ, and the nitrogen gas may be allowed to flow into the heating furnace 6.

Then, the gut whose tension when the strain rate τ is stretched to 10% as described above is set to the desired tension--that is, 28 to 60 kg / mm ² --is 27.2 kg of weft yarn and 21,8 kg of warp yarn. The repulsion coefficient and the durability were measured in order to test the practicality by mounting the racket under the tension of.

Specifically, the repulsion coefficient is measured as shown in FIG.
The racket 10 on which a plurality of guts 15 are stretched is suspended on the jig 11, and the tennis ball 13 stored in the launcher 12 is launched from the launcher 12 to the gut 15 of the racket 10. The tennis ball 13 is collided and repelled as shown by arrows Q and Q ', the velocity of the tennis ball 13 before and after the collision is measured by the ball velocity measuring device 14, and the restitution coefficient is calculated from the velocity ratio before and after the collision.

In the durability test, as shown in FIG. 7, a racket 10 on which a plurality of guts 15 are stretched is provided, and a launcher 12 in which a tennis ball 13 is stored is provided.
Fire a tennis ball 13 at a speed of 12 to 30 m / s,
The tennis ball 13 was continuously and repeatedly collided against the gut 15 in the direction of arrow R, and the number of collisions of the tennis ball 13 until the gut 15 was cut was measured and judged. The gut
In the repulsion coefficient and durability test of 15, the samples B and K were measured as typical examples, and as the conventional gut, sample b was measured as a comparative product. Furthermore, in the durability test, comparative experiments were conducted using samples G, K, b and c.

 The experimental results are shown in Tables 7 and 8, respectively.

As described above, the coefficient of repulsion and the durability were dramatically improved, and the excellent repulsion and durability were proved. In this way, the tension when stretched to a strain rate τ of 10% is 28 kg / mm ²
If it is set to -60 kg / mm ² , it is possible to obtain a synthetic fiber that matches the desired gut.

Further, FIG. 8 is a graph showing the result of viscoelasticity measurement which is a measure of the impact resilience of the gut of the present invention. The sample used for the viscoelasticity measurement was obtained by stretching a commercially available nylon gut having an outer diameter of 1.3 mm at a stretching rate of ψ8%, fixing the gut on a predetermined metal frame, and further heating at 172 ° C. After heating at T for 10 minutes and allowing to cool for a predetermined time, the gut was removed from the metal frame and subjected to a tensile test. The tensile test was carried out at a tensile rate of 20 mm / min, tension when the distortion rate τ was shown stretched 5% was 12.9 kg / mm ² (conventional gut (untreated GATT) is 7.4 kg / mm ²⁾ . Then, the viscoelasticity of the gut of the present invention and the conventional product were measured. As can be seen from this figure, the so-called mechanical dispersion shifts to the high temperature side, and the value of tan δ, which is a measure of the impact resilience of synthetic fibers, is within the range of −5 ° C. to 30 ° C. While the gut shows a maximum value of 0.082, the gut of the present invention 0.0
It was significantly reduced to 68, which also showed that the energy loss was small, and it was proved that the impact resilience was improved.

〔The invention's effect〕

According to the above configuration, the tension S when the strain rate τ is 10%
28 kg / mm ² since 60 kg / mm ² is set to, yet racquet gut of synthetic fibers of polyamide, rigidity rich in high elasticity, excellent in water resistance durability, feel when hitting the ball and The repulsive force of the ball is excellent, and it is possible to realize a gut in which the thread does not loosen during use. In particular, it is easily stretched when hit and easily spun. Moreover, since the gut is made of synthetic fiber, it is not expensive like the animal muscle gut, and it is possible to manufacture a gut having excellent characteristics that is uniform and inexpensive.

[Brief description of drawings]

FIG. 1 is a tension strain diagram showing an example of the tension characteristic of the gut according to the present invention in comparison with a conventional gut, and FIG. 2 is an enlarged cross-sectional view illustrating a commercially available gut as a material for the gut according to the present invention. FIG. 3 is a simplified device diagram showing an example of the manufacturing method, FIG. 4 is a simplified device diagram showing another example of the manufacturing method, and FIG.
FIG. 6 is another tension strain diagram, FIG. 6 is a simplified experimental device diagram for measuring the coefficient of restitution, FIG. 7 is a simplified experimental device diagram for performing a durability test, and FIG. 8 is a gut according to the present invention. FIG. 4 is a viscoelastic characteristic diagram showing the viscoelasticity of Comparative Example in comparison with a conventional gut. τ ... strain rate, S ... tension

Claims (2)

[Claims] 1. A racket gut made of polyamide-based synthetic fiber, having a tension S of 28 when the strain rate τ is 10%.
racquet gut, characterized in that it is set in ^{kg / mm 2 ~60kg / mm 2} . 2. A heating temperature T (unit: while applying a tension of 5 to 17 kg / mm ² or stretching at a strain rate of 8 to 20%).
Heating temperature (x) (unit:
Min) is heated as x ≧ exp {(1300 / T) −6.5}.