JPS62201166A - Gut for racket and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a racket gut and a manufacturing method thereof.

[Conventional technology and its problems]

Conventionally, guts used in tennis and badminton rackets have been made by twisting the sinew of animals such as sheep and whales to a moderate degree and hardening them with a binding agent to form bristles.

Such conventional guts have high rigidity and extremely high elasticity, exhibiting excellent physical properties such as little sagging during use, and are also excellent in feel and sound when hitting the ball. However, it has the disadvantage that it has extremely poor water resistance, and its tension and strength drop significantly in rainy weather, and moreover, the animal muscle is generally expensive.

In order to overcome these drawbacks of animal muscle guts, synthetic fiber guts made by appropriately twisting monofilaments or multifilaments and processing them with resin have been developed and have been widely used. There are polyamide and non-polyamide types of synthetic fiber guts, and the former is made of nylon 6, nylon 66, and their copolymer fibers, and has superior water resistance and durability compared to animal muscle guts. This has the disadvantage that the rigidity and elastic modulus are poor, and the threads tend to loosen during use, resulting in insufficient feel when hitting the ball and insufficient ball repulsion.

The latter also includes polyether ether ketone (Japanese Patent Application Laid-open No.
-21073), polyvinylidene fluoride (JP-A-57-89611), and polyacetal (JP-A-60-279514).
Although both had high rigidity, they had the drawback of poor repulsion.

Furthermore, recently, a method has been developed in which thin metal wires are spirally wound around polyamide monofilament and the thin metal wires are covered with synthetic fibers (Japanese Utility Model Publication No. 15301/1983), and carbon fibers are used instead of the thin metal wires. So-called composite strings have also been developed, such as those wrapped around polyamide fibers (Japanese Utility Model Publication No. 58-50937) or composite strings made of polyamide fibers and aramid fibers (Japanese Patent Application Laid-open No. 59-64073). Although it has high rigidity, it has a low degree of elongation and poor repulsion, resulting in a poor feel when hitting the ball and the ball does not travel far.

〔the purpose〕

The present invention solves these conventional problems and provides a racket gut that is excellent in water resistance and durability, has high rigidity, and is rich in elasticity, and also provides such a high-performance, high-quality racket. The purpose is to easily and inexpensively manufacture gutters for use.

[Means for solving the present invention]

The racket string according to the present invention is a racket string made of polyamide synthetic fiber, and has a strain rate τ of 1.
Tension S at 0% is 28 kg/mm ~ 60k
g/mrd. In addition, the method for manufacturing the gut according to the present invention has a tension of 5 to 17 kg/m.
rrr or while stretching by a strain rate of 8 to 20%, heating time (x) (unit: minutes) under heating temperature T (unit: 2 degrees Celsius) of 150 to 200 degrees Celsius, X≧ e x p
((1300/T) -6,51).

[Effect]

According to the configuration of the racket gut described above, the distortion rate is 10.
%, the tension is 281g/ which is the optimum value for actual use.
m rd to 60 kg/mrrr, the racket gut has rich elasticity, excellent durability, and excellent repulsion. In addition, according to the above-mentioned manufacturing method of Guttu, the heated and stretched polyamide synthetic fiber is stretched under a predetermined high tension at a temperature near the melting point of the crystal, so that the crystal having a folded structure is partially stretched. When loosened, the fibers are reorganized and woven, increasing the melting point of the crystals and improving heat resistance. Furthermore, by applying these prescribed heat treatments, the degree of orientation of the amorphous chain segments increases, and the mechanical dispersion caused by micro-Brownian motion of the segments shifts to the high temperature side, resulting in synthetic fibers with low energy loss. produced.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the drawings.

Figure 2 shows the outer diameter 1, lu used for racket guts.
+ ~ 1.4 Dragon's well-known synthetic fibers are exemplified, and (I) and (II) include a core wire 1 made of polyamide synthetic fiber and a core wire 1 also covered by twisting and resin processing. It consists of a large number of windings 2 of heat-resistant synthetic fiber containing polyamide synthetic fiber, and (DI) is a multifilament 3 made of polyamide synthetic fiber.
It is molded by twisting and resin processing.

The racket gutter of the present invention is made by heating and stretching the above-mentioned synthetic fibers under predetermined processing conditions.Although not shown in the drawings, a monofilament of synthetic fibers mainly composed of polyamide is used as a core wire and/or Alternatively, it is also possible to use it for winding and heat-stretch the constructed synthetic fiber string.

The processing conditions are determined by the heating temperature, heating time, and tension of the synthetic fiber during heating, and these conditions are set to values that allow desired elasticity, durability, etc. to be achieved. In other words, if the heating temperature is too low, the treatment effect will be small and the intended purpose will not be achieved.
If it is too high, the problem arises that oxidative deterioration of the fibers occurs, resulting in poor durability. Regarding the tension, if the tension is too low, high elasticity synthetic fibers are particularly useful. If the tension is too high, the synthetic fibers may break. Desired processing conditions are determined by taking these points into consideration. . Specifically, the tension W of the synthetic fiber before processing is 5.0 kg/mn? ~17+r/m
rd. (Preferably 10kg/mrrr~15kg/
mm) or the stretching ratio ψ of the fiber is set to 8% to 20% (preferably 13% to 18%), and the heating temperature T is 15%.
The temperature is set at 0°C to 200°C (preferably 165°C to 190°C).

Furthermore, the heating time X is expressed and determined as a function of the heating temperature T, as shown in equation (i) below.

x=ex≧exp{(1300/T) 6.5l--
(i) Therefore, when the heating temperature T is low, the heating time X takes a long time. Note that equation (i) indicates the minimum time required for heating, and it is free to set the time to a longer time than this. Further, the heating temperature T is in "°C", and the heating time X is in "minutes". However, polyamide synthetic fibers heated and drawn under such processing conditions are stretched under a predetermined high tension at a temperature near the melting point of the crystals, so that the crystals, which have a folded structure, are partially stretched. When loosened, the fibers are reorganized and the melting point of the crystal increases,
Improves heat resistance. Furthermore, by applying these prescribed heat treatments, the degree of orientation of the amorphous chain segments increases, and the mechanical dispersion caused by micro-Brownian motion of the segments shifts to the high temperature side, resulting in synthetic fibers with low energy loss. produced.

Therefore, the synthetic fiber has high elasticity and excellent durability.
This product has excellent repulsion, making it ideal as a racket gutt.

Next, the manufacturing method and characteristics of the gutt according to the present invention will be explained in detail.

Generally, in conventional methods, untreated synthetic fibers are stretched and heated by zone stretching and zone heat treatment.
is small and the heating time X is also short, making it impossible to achieve high elasticity.

Therefore, in the present invention, a heating stretching process was carried out by the method described below. In addition, in the method described below, commercially available synthetic fibers subjected to the zone stretching and zone heat treatment described above are used as the synthetic fibers before processing, and the characteristics are as follows when stretched at a strain rate τ of 10%. The tension S is 14.0~
27.0kg/mrd, tensile strength 60-70k
+r/mrd.

In FIG. 3, reference numeral 5 denotes a manufacturing apparatus for the gutt according to the present invention, which includes a heating furnace 5 in which the synthetic fiber 4 is heated, and a heating furnace 5 disposed outside both ends of the heating furnace 5 to engage the synthetic fiber 4. It consists of a pair of left and right pulleys 7, 7, and a pair of left and right weights 8, 8 suspended from the synthetic fibers 4.

Thus, the synthetic fiber 4 set at a predetermined position is subjected to a predetermined load W by the weight 8.8, and a constant tension W'-i.e., 5 kg/m rd ~ 17 k
g/m n(- is given, then a certain predetermined time 1
It is heated to 50 to 200°C and stretched.

Table 1 illustrates the processing conditions for the guts manufactured by the manufacturing equipment, and Table 2 shows the tensile strength characteristics of the guts manufactured under the processing conditions in Table 1, compared to a commercially available conventional product (Dunlop DTS- 2000), and the tension S when stretched at strain rates τ of 5% and 10% is shown together with other data. still,
In Table 1, samples AF used nylon monofilament, and sample G used Dunlop 1DTs-2000. Further, the moisture content of the sample after heating was approximately 0.3%.

[Margin below]

Table 1 As shown in Table 1, the tension W is 5.4 kg.
/mrd ~13kg/mrd,
Predetermined conditions (5,0kg/m rrr ~17kg/
m rd ), and the heating temperature T is 1 in both cases.
The temperature is set to 73 degrees, and the heating time X is calculated by equation (i), and the heating time is x#2 minutes or more.

Furthermore, the tensile strength characteristics shown in Table 2 were conducted in accordance with JIS-L1070, and the tension S when stretched at a strain rate τ of 10% increased significantly; Okg/
mrrf~5B, 4kg/mrrf) Breaking strength (k+r
) also increases by about 1.3 times. Further, FIG. 1 is a plot of the relationship between the strain rate C and the tension S shown in Table 2. From this figure, the tension W during processing is 10 kg/
It turns out that it is preferable that it is m rd or more, and
It turns out that the longer the heating time X is, the better.

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

Specifically, in the stress relaxation experiment, an initial tension of 25 kg/mrrf was applied to the inventive string and the conventional string using a tensile tester, the stretching ratio was kept the same, and the retention rate was measured after 1 hour.

In addition, the energy loss test was conducted by stretching the inventive string and the conventional string at a speed of 200 m/n+in, respectively, in a tensile testing machine, and stretching the string at a rate of 30 kg/mrrr or 40 kg/mM.
Applying a tension of The energy loss is calculated by dividing the latter by the former.

The results of the stress relaxation test are shown in Table 3, and the results of the energy loss test are shown in Table 4.

[Margin below]

These results confirmed that the gutts of the present invention have less stress relaxation and less energy loss than the conventional gutts, and have been proven to have a high repulsive force.

Furthermore, another manufacturing method will be explained in detail.

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

Thus, the synthetic fiber 4 is set at a predetermined position, and the rotational speed of the rollers 9 on the winding side is changed to the roller 9 on the sending side.
．． The desired string is obtained by passing through a heating furnace 6 which is set at a rotational speed higher than the rotational speed of 9, and which is set to a predetermined heating condition while always maintaining a constant stretching ratio ψ.

Table 5 exemplifies the processing conditions for the guts manufactured by the manufacturing equipment, and Table 6 shows the tensile strength characteristics of the guts manufactured under the processing conditions in Table 5 in comparison with conventional products on the market. It has been made clear.

[Margin below]

Table 6 However, in Table 5, samples H-J use nylon monofilament, and the samples include Dunlop DTS
-2000 was heated and stretched.

Furthermore, the tension at the time of sending out the synthetic fiber 4 is 2.3 kg.
/ m rd and the stretching ratio 4 is 10% and 15%
and the heating time X was (
Calculated by formula i), and the heating time x is set to 2 minutes or more.

In addition, in Table 6, commercially available conventional products b to d are Dunlop DTS-2000 and Goshen Audio.
A comparison was made using Sheep Micro and nylon monofilament. These results demonstrate that both the elastic force and the breaking strength can be greatly improved by applying the above-mentioned heating and stretching treatment. Further, FIG. 5 is a plot of the relationship between the strain rate τ and the tension S in Table 6. It is clear from this figure that it is preferable for the stretching ratio ψ of the processing conditions to be larger. In this manufacturing apparatus 5, instead of keeping the stretching ratio ψ constant, the tension W may be kept constant, or nitrogen gas may be allowed to flow into the heating furnace 6.

Therefore, the tension when stretched to a strain rate τ of 10% as described above is the desired tension - that is, 28 to 60 kg/mrr.
? - The racket was set to 27.2 kg for the weft string and 21.8 kg for the warp string, and the practicality was tested by attaching the string to the racket, and the repulsion coefficient and durability were measured.

Specifically, as shown in FIG. 6, the repulsion coefficient was measured by suspending a racket 10 on which a plurality of guts 15 were stretched from a jig 11 and storing it in a firing device 12. A tennis ball 13 is launched from the launch device 12, and the tennis ball 13 is bounced by the guts 15 of the racket IO as shown by arrows Q and Q'', and the velocity of the tennis ball 13 before and after the collision is defined as the ball velocity. The repulsion coefficient is measured by the measuring device 14 and calculated from the speed ratio before and after the collision.

Furthermore, as shown in FIG. 7, the durability test was carried out by providing a racket 10 with a plurality of guts 15 stretched thereon, a firing device 12 in which a tennis ball 13 was stored, and 30m/30m from the firing device 12. Tennis ball 1 at a speed of s
3, the tennis ball 13 is continuously repeatedly collided with the Gantt 15 in the direction of the arrow R, and is repulsed by the gaso) 15.
The judgment was made by measuring the number of collisions of the tennis ball 13 until it broke. The repulsion coefficient and durability test of Gut 15 were performed using Samples B and K as representative examples, and the conventional Gut 15 was measured using Sample S as a comparative product. Furthermore, for the durability test, six comparative experiments were conducted using samples G, b, and c, and the results are listed in Tables 7 and 8, respectively.

As mentioned above, both the repulsion coefficient and durability were dramatically improved, and superiority in repulsion force, durability, etc. was also proven. In this way, the tension when stretched to a strain rate τ of 10% is 28 kg.
If the weight ratio is set to 60 kg/mrrf, it is possible to obtain synthetic fibers that meet the desired weight.

Furthermore, FIG. 8 is a graph showing the results of viscoelasticity measurement, which is a measure of the repulsive elastic force of the gut of the present invention. The sample used for the viscoelasticity measurement was made by stretching a commercially available nylon gut with an outer diameter of 1.3 fins at a stretching ratio of ψ8%, fixing the gut in a predetermined metal frame, and heating it at 172°C. After heating at temperature T for 10 minutes and cooling for a predetermined time, the gut was removed from the metal frame and subjected to a tensile test. The tensile test was conducted at a tensile speed of 2011 m/min, and the tension when stretched to a strain rate τ of 5% was 12.9 +r/mm (conventional gutt (untreated gutt) was 7.4 kg). /
mrrr). Then, the viscoelasticity of the inventive gutt and the conventional product was 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 rebound resilience of synthetic fibers, is lower than that of conventional products in the commonly used atmospheric temperature range of -5°C to 30°C. Guttu shows the maximum value of 0.082, while Guttu of the present invention shows a maximum value of 0.0.
68, which shows that the energy loss is small and proves that the repulsion elastic force is improved.

〔Effect of the invention〕

According to the above configuration, the tension S when the strain rate τ is 10% is set to 28 kir/m % to 60 kg/m rrl, so even though the racket string is made of polyamide synthetic fiber, it has high rigidity. It is possible to realize a grip that is rich in elasticity, has excellent water resistance and durability, has excellent feel when hitting the ball and has excellent ball repulsion, and has no risk of the thread loosening during use. In particular, it stretches moderately when struck and is easily spun. Furthermore, since the guts are made of synthetic fibers, they are not as expensive as animal muscle guts, and can be manufactured at low cost and with uniform and excellent characteristics.

[Brief explanation of drawings]

Fig. 1 is a tension strain diagram showing an example of the tension characteristics of the string according to the present invention in comparison with conventional strings, and Fig. 2 is an enlarged cross section illustrating a commercially available string which is the material for the string according to the present invention. 3 is a simplified device diagram showing an example of the same manufacturing method, FIG. 4 is a simplified device diagram showing another example of the manufacturing method, and FIG.
The figure is another tension strain diagram, Figure 6 is a diagram of a simplified experimental setup for measuring the coefficient of repulsion, Figure 7 is a diagram of a simplified experimental setup for conducting a durability test, and Figure 8 is a diagram of the gutt according to the present invention. FIG. 2 is a viscoelastic characteristic diagram showing the viscoelasticity of the product in comparison with that of a conventional product. τ...Strain rate, S...Tension Figure 1 Strain rate τ (@A) Figure 2 (1) (II) (III
)5 Figure 4 Figure 5 Figure 6 Figure 1 Figure 7

Claims (1)

[Claims] 1. A racket string made of polyamide-based synthetic fibers, which has a tension S of 28 kg when the strain rate τ is 10%.
A racket gut characterized by being set to /mm^2 to 60kg/mm^2. 2. The heating time (x )
A method for manufacturing a racket string, characterized in that heating is performed in minutes (unit: minutes) as follows: x≧exp{(1300/T)−6.5}.