TW201505691A - Racquet string and method for producing same - Google Patents

Abstract

This racquet string (1) is a braided string including core threads (2), sheath braided threads (4) on the outer side of the core threads, and a surface resin layer (5) on the outer side of the sheath braided threads; hot-melt-type flat monofilaments (3) being wound flatly around the core threads (2), and the core threads (2) and the sheath braided threads (4) being integrated by thermobonding. This string production method involves flatly winding the hot-melt-type flat monofilaments (3) around the core threads (2), braiding the sheath braided threads (4) over the surface of the monofilaments, heating the resulting braided threads to or above the melting point of the flat monofilaments (3), and melting the flat monofilaments (3) to integrate the core threads (2) and the sheath braided threads (4) by thermobonding. A highly durable racquet string is thereby provided, with which is obtained a comparatively hard hitting feeling and a pleasant hitting sound, and with which there is little tension loss.

Description

String for racket and manufacturing method thereof

The present invention relates to a synthetic string for a racket of badminton, tennis, squash, and the like. In particular, it relates to a racquet string having a hard playing feeling and comfortable sound for badminton, a small tension loss, and high durability.

Conventionally, as a synthetic string for a racket such as a tennis ball, a badminton or a squash, a string or a weaving (woven) in which a fine monofilament is wound on the outer side of the monofilament or the multifilament of the core is proposed. String. For example, in a string for badminton, a string which is woven (woven) on a multifilament of a core as a fine monofilament having a diameter of about 0.06 mm of a sheath is used. The slender string is usually excellent in sound or sound but has poor durability, so it is expected to satisfy the development of the strings of the two.

Patent Document 1 proposes a case where a copolymerized thermoplastic resin solution is applied to a core wire. Patent Document 2 proposes a case where a material having a melting point lower than that of a core material is sheathed and melted. Patent Document 3 proposes a case where a sheath resin is melt-coated on a core wire and then woven and thermally fused.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-304678

[Patent Document 2] Unexamined Japanese Patent Publication No. Sho 60-86598 (Japanese Patent Application No. 59-120410)

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2007-177355

However, in the method of Patent Document 1 in which a resin obtained by dissolving a resin in a solvent is subjected to resin processing, there is a problem in the environment due to the use of a solvent, and it is necessary to select a resin which does not dissolve the solvent of the core fiber and can be used. restricted. Further, the concentration or viscosity of the resin during processing tends to change due to temperature change, solvent evaporation, and the like, and there is a problem that quality unevenness is likely to occur. Further, when the core wire is a multifilament, the resin solution enters the inside of the core wire structure, so that the amount of the surface resin is also reduced. The hot-melt method of Patent Document 2 has an advantage that no solvent is used, but a preferred amount of resin used is 25% by weight or more of the string. When such a large amount is used, the diameter of the string becomes thick, and the resin hardly contributes to the strength. Therefore, it is difficult to obtain a string having a fine and high strength, and there is a problem that both the feeling and the sound are deteriorated. Patent Document 3 discloses a case where a resin is melt-coated on a core wire. However, it is technically difficult to melt and apply the film on the surface of a fine core. When the amount of coating is excessive, the same as in Patent Document 2 described above. The diameter of the obtained string becomes thick, and there is a problem that the feeling is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and to provide a racquet string which can obtain a relatively hard hit and comfortable sounding and which has low tension loss and high durability.

The racquet string of the present invention includes a core wire, a sheath plied yarn on the outer side of the core wire, and a braid type of a surface resin layer on the outer side of the sheath plied wire, wherein the core wire is wound flat in the core wire There is a hot-melt flat monofilament, and the core wire and the sheath plied wire are thermally integrated.

The method for producing a racquet string according to the present invention is a method for producing a racquet string comprising a core wire, a sheath plied yarn on the outer side of the core wire, and a tape type of a surface resin layer on the outer side of the sheath plied yarn. It is characterized in that a hot-melt flat monofilament is wound flat on the core a wire, which is knitted on the surface of the sheath, and the obtained braided wire is heated to a temperature above the melting point of the flat monofilament, so that the flat monofilament is melted and the core wire and the sheath plied wire are thermally integrated. Then, a surface resin layer is formed on the outer side of the sheath plied strand.

The present invention can provide a string for a racquet, which comprises a core wire, a sheath plied yarn on the outer side of the core wire, and a surface resin layer on the outer side of the sheath plied wire, and is wound flat by winding a hot-melt flat monofilament The core wire, and the core wire and the sheath plied wire are thermally integrated, and the tension loss when the string is set on the racket is small, and a relatively hard feeling and comfortable sound can be obtained when playing the ball, and the durability is high. .

1‧‧‧racing string

2‧‧‧core

3,6,7,8‧‧‧flat monofilament

4‧‧‧ sheath joint line

5‧‧‧Surface resin layer

10‧‧‧Orthogonal friction test device

11, 12‧‧‧ string

13a, 13b‧‧‧ string fixture

14‧‧‧Load

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an exploded perspective view of a string for a racket in an embodiment of the present invention.

2A-C are cross-sectional views of a flat monofilament in an embodiment of the present invention.

Fig. 3 is a schematic explanatory view of an orthogonal friction test apparatus used in an embodiment of the present invention.

In the case of the fusion-bonding method in which the solvent is not used, it is important to keep the amount of the resin to be minimized while maintaining the adhesion. The inventors of the present invention have conducted intensive studies focusing on such a situation, and as a result, found that the thickness is thin. The hot-melt flat monofilament is flatly wound and coated on the outer surface of the core wire, and the flat monofilament is heated and melted, and the core wire and the sheath plied strand are thermally integrated, and the present invention is completed. . It has also been found that it is further preferred that in order to improve the adhesion between the sheath strands, it is important that the fiber surface of the sheath strands is softened and partially localized by raising the heat fusion temperature to the melting point range of the sheath strands. Fusion.

The present invention discloses a flat-shaped monofilament of a hot-melt type in a string for a racket type of a tape type including a core wire, a sheath plied yarn on the outer side of the core wire, and a surface resin layer on the outer side of the sheath plied yarn. The wire is wound flat on the core wire, and the core wire and the sheath plied wire are thermally integrated. When the weight of the string is set to 100% by weight, the ratio of the flat monofilament is preferably in the range of 2 to 12% by weight. Further preferably, it is 2.5 to 8% by weight. As long as it is in the above range, a fine and high-strength string can be obtained.

In the present invention, it is preferable that the heat of the flat monofilament is removed, and the heat of the core wire and the sheath plied strand is further integrated, and the outer sheath portion of the sheath is also partially fused to each other. Thereby, the sheath plied yarns are also connected to each other, thereby achieving an improvement in the playing sound and an improvement in durability.

The melting points of the core wire, the sheath plied wire and the flat monofilament are preferably represented by the following formula. As long as it is the following formula, when the heat of the flat monofilament is melted, the strength of the core wire and the sheath plied strand is prevented from being lowered, and a fine and high-strength string can be obtained.

TM3<TM2≦TM1

Wherein, TM1: melting point of the core wire, TM2: melting point of the sheath strand, TM3: melting point of the flat monofilament.

In the manufacturing method of the present invention, a hot-melt flat monofilament is wound flat on a core wire, and a sheath plied yarn is knitted on the surface thereof, and the obtained braided wire is heated to a melting point (TM3) or more of the flat monofilament. At the temperature, the core wire and the sheath plied strand are thermally joined together by melting of the flat monofilament. The temperature following the heat is preferably TM3 + 30 ° C or more and TM 2 + 15 ° C or less. Further, it is preferably a temperature of TM3 + 40 ° C or more and TM 2 + 10 ° C or less. As long as it is in the above range, the core wire and the sheath plied strand are thermally heated and the sheath plied strands may be partially fused to each other.

The stretching ratio of the above-mentioned braided wire at the time of heat is preferably 0.95 to 1.20 times. Further, the preferred stretching ratio is 1.00 to 1.10 times. If heat is applied at the above stretching ratio, heat shrinkage can be prevented under stretching, and a fine and high-strength string can be obtained.

The thickness of the flat monofilament is preferably from 0.015 to 0.06 mm, more preferably from 0.02 to 0.05 mm. The flatness (width/thickness) of the flat monofilament is preferably from 1.5 to 100, and more preferably from 2.5 to 80. As long as the thickness and flatness of the flat monofilament are in the above range, the core wire and the sheath portion are made The strands heat then and may also cause the sheath plied strands to be partially fused to each other.

When the flat monofilament is wound flat on the surface of the core wire, care must be taken as follows.

(1) When a flat monofilament is produced, the winder is wound up without being twisted in the transverse direction, and is taken out from the transverse winding body when wound around the core wire, and is not twisted.

(2) When a flat monofilament is produced, when winding is performed by winding in a longitudinal winding machine, when winding is wound on the core wire, the winding body is drawn from the same direction and is not twisted. twist.

The coverage of the flat monofilament wound around the core wire with respect to the surface of the core wire is preferably 15 to 70%, more preferably 20 to 50%. As long as it is the range, the core wire and the sheath plied strand are thermally heated and the sheath plied strands may be partially fused to each other.

The cross-sectional shape of the flat monofilament wound around the core wire is preferably a flat shape having irregularities. As long as the cross-sectional shape is uneven, when the flat monofilament is wound around the core wire and the sheath-knot strand is knitted, friction is generated and the fabric can be firmly woven, and the adhesion can be improved in a small amount.

The core material is not particularly limited, and is preferably a high-strength polyamide filament. Examples of the polyamines include aliphatic polyamide resins such as nylon 6, nylon 66, nylon 610, nylon 612, nylon 46, nylon 56, nylon 410, and nylon 12, and semi-aromatics such as nylon 9T, nylon MXD6, and nylon 6T. A polyamidamine resin. A good high-strength multifilament thread of nylon 6 or nylon 66 is exemplified. It is generally known that high-strength polyamide wires are used as industrial materials such as tire cords.

The preferred single yarn fineness of the core wire is 2 to 10 deci tex, and the total fineness is 1500 to 7000 deci tex. The preferred filaments of the core wire form from 150 to 3,500.

When the melting point of the core wire is set to TM1, TM1 is preferably 170 ° C or higher, more preferably 200 ° C or higher. Further, in the present invention, the melting point is a value expressed by a peak temperature measured by a differential scanning calorimeter (DSC) at a temperature rising rate of 20 ° C /min. The physical properties of the core wire have a great influence on the physical properties of the string. The preferred multifilament has a strength of 5.0 to 12.0 cN/deci tex and an elongation of about 16 to 25%. The core wire can also be used or mixed with other filaments as needed.

The core wire is preferably used for twisting. In this respect, it is preferable in terms of bundleability, roundness, elongation, and the like of the filament bundle, and it is preferably used in the range of 30 to 300 times/m as the number of twists. In order to improve the adhesion of the core wires to each other and to impart appropriate hardness to the core wires, it is also possible to carry out resin processing with a resin having an adhesive property. Further, a low-melting thermal adhesive fiber may be mixed in the core wire.

As the sheath plied yarn (melting point: TM2), it is preferred to use a filament composed of a resin having the same melting point as the melting point of the core wire or lower than the melting point of the core wire and higher than the melting point of the low melting point resin wound around the core. As the raw material, a polyamine-based resin similar to the core wire is preferable, and as an example, nylon 6, nylon 66, nylon 610, nylon 612, nylon 46, nylon 56, nylon 410, nylon 11, nylon are preferably used. 12 or more aliphatic polyamines or such copolymerized polyamines. In the case where the core component is nylon 66 or nylon 6, a nylon 6 or nylon 6/66 copolymer, a nylon 6/12 copolymer or the like is preferably used as the sheath strand. Further, it is also possible to blend nylon 6 with a copolymerized nylon filament having a low melting point of about 5 to 80%.

As the sheath plied yarn, it is preferred that the single yarn fineness is larger than the single yarn fineness of the multifilament of the core yarn, and it is preferable to use a filament obtained by twisting one monofilament or about two to four filaments. As a plying line. In the case where the single yarn is too thick or the number of filaments is too large, the diameter after weaving becomes thick, which is not preferable. Further, it is also possible to use an ellipse or a flat cross section in which the cross-sectional shape of the filament is used. It is also preferable to use a joined type cross-sectional filament disclosed in Japanese Laid-Open Patent Publication No. 2008-48867, which is hereby incorporated by reference. The preferred single yarn fineness of the sheath plied yarn is about 10 to 100 deci tex. Preferably, it is woven by using 8 to 32 strands of the single yarn fineness to form a sheath portion.

The hot-melt flat monofilament is wound flatly on the outer side of the core wire to knit the sheath plied strand. Weaving can be carried out by a known method. It is preferable to use a knitting machine of, for example, 16 spindles. The step of winding the flat monofilament and the step of weaving the sheath plied strand may be separate steps or may be continuous.

The hot-melt flat monofilament is preferably used to have a lower melting point than the core and the sheath The filaments of the strands and the raw materials which have good adhesion to the filaments of the strands and the strands of the sheath. The resin which is 100 ° C to 180 ° C in the range of the preferred melting point (TM3) and which has a melting point lower than that of the core fiber or the sheath plied fiber is selected as the resin of TM3 < TM2 ≦ TM1. Examples of the resin include a copolymerized polyamine resin or a polyurethane obtained by copolymerizing two or more kinds of aliphatic nylons selected from the group consisting of nylon 6, nylon 66, nylon 12, nylon 11, nylon 610, and nylon 612. (poly urethane) resin. More preferably, it is a resin which is 30 ° C or more lower than the melting point of the sheath plied fiber. Specifically, nylon 6/12, nylon 6/66/610, nylon 6/66/12, nylon 6/12/610, nylon 6/12/612, nylon 12/612, nylon 6/66/610 can be cited. /12, Nylon 6/66/610/612 copolymer, etc., but it is not limited to these, and as a heat-fusible resin, a heat-fusible fiber can be suitably selected from the well-known copolymerized nylon.

According to the study by the inventors of the present invention, in order to obtain a string which is good in sound and sound, and which is durable even if it is fine, the amount of the adhesive component and the state of application are important as described above, and it is important that one side is sufficiently provided. The adhesive side reduces the amount of the amount as much as possible. Therefore, in the present invention, a flat monofilament is used as a material for winding. In the case of a multifilament having a large number of filaments, it is difficult to uniformly control the thickness or width of the line in the wound state, and a portion where the diameter of the string is thick or a void appears, which is not preferable.

The preferred single yarn fineness of the flat monofilament is 10 to 150 deci tex. A better single yarn has a fineness of 20 to 100 deci tex. It is preferable that the flat monofilament is wound flat on the core wire, and the bobbin for winding may be plural.

After the core wire and the sheath plied strand are thermally joined together by melting of the flat monofilament, a surface resin layer is formed on the outer side of the sheath plied strand. The surface resin layer is formed by immersing or melt-coating a nylon resin obtained by dissolving in a solvent. The nylon resin is not particularly limited, and aliphatic polyamines such as nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11, nylon 12, and semi-aromatics such as copolymerized polyamine and nylon 9T can be used. Polyamide. The color, appearance, and durability can be improved by dipping or coating. And can proceed as needed Color, heat treatment, printing, oiling, etc.

Second, use the schema to illustrate. 1 is an exploded perspective view of a string 1 for a racket in an embodiment of the present invention. In the racquet string 1, the hot-melt flat monofilament 3 is wound flat on the core wire 2, and the core wire 2 and the sheath plied wire 4 are thermally integrated and integrated (the figure is shown for easy understanding) The shape of the flat monofilament before melting). A surface resin layer 5 is formed on the surface of the sheath plied line 4. An example in which the core 2 is a multifilament is shown in Fig. 1, but it may also be a monofilament. The number of multifilaments can also be arbitrarily selected. Further, the sheath plied line 4 shows an example in which four monofilaments having a circular cross section are connected, but it is also possible to connect two to eight. Alternatively, 2 to 4 monofilaments may be arranged side by side.

In the present invention, the flat monofilament is preferably at least one selected from the group consisting of a plurality of cross-sectional circles connected in a row shape, a plurality of concavo-convex shapes having a circular cross-section and a smooth surface, and an oblong shape. . For example, the cross-sectional shape shown in Figs. 2A-C. Fig. 2A is a flat monofilament 6 in which five cross-sections are circularly connected, and the flatness L/D is about 5. Where L represents the width and D represents the thickness. For example, L = 0.165 mm and D = 0.035 mm. Fig. 2B is a flat monofilament 7 having a smooth surface and irregularities. Fig. 2C is a flat monofilament 8 having an oblong shape with no irregularities on its surface.

[Examples]

Hereinafter, the embodiment will be specifically described. Furthermore, the present invention is not limited to the following examples. The evaluation of the monofilament and the string in the following examples was carried out in the following manner.

<Physical test>

The strength, knot strength, and elongation are based on the measurement method of JIS L1013. The diameter was measured using a micrometer, and the average value was set to a diameter while the monofilament was slightly rotated.

<bounce, rigidity>

In the case of a badminton string, one string is stretched at a tension of 20 pounds and fixed at both ends with a clamp (clamping interval 30 cm). Using a pendulum hammer, the center of the string is struck from the fixed position at a right angle to the string in a horizontal direction, and the movement of the string after the collision (displacement amount) is measured at intervals of 1/1000 second. And stress, using the following calculation method to find the rigidity (pounds / eng 吋) and rebound rate (%).

Rigidity = maximum stress P (pounds) / horizontal displacement maximum displacement L (inch)

Rebound rate (%) = (S2/S1) × 100

S1: Area of the part of the stress-strain (displacement) curve (de-back) that collides to the maximum displacement (de-part)

S2: the area from the maximum displacement position of the stress-strain curve to the zero displacement (return)

The higher the rigidity value, the harder it is in the state of being stretched in the racket, and the lower the value, the softer it is.

The higher the rebound rate, the less energy loss in the collision and the greater the rebound (Reference: Rod Cross "Laboratory testing of tennis string" Sports Engineering (2000) 3, 219-230).

<Durability 1> Orthogonal friction

Description will be made using the orthogonal friction test apparatus 10 shown in FIG. The strings 11 are fixed at both ends (13a, 13b) in a state where a tension of 30 lbs is applied in the horizontal direction of the arrow P. The same string 12 is crossed with the string 11 in a horizontal direction, and one end 12a is fixed, and a load of 14 kg is applied to the other end 12b to suspend it. The string 12 is suspended at right angles from the chord 11 fixed at both ends on the same horizontal plane, and is stretched downward in the vertical direction under the weight of the load. In a state where a load is applied to the string 12, it is returned to the movement 10 mm in a horizontal right-angle direction at a speed of 1 second as indicated by an arrow Q. The evaluation was carried out in the raised state of the string 12 after the friction was removed. The number of rubbing times at which the string (12) was cut or raised was evaluated. The case where the fluffing was small after 200 rubs was set to 200 or more.

<Durability 2> Durability test under badminton

Set the string to 25 lbs on the racket and bounce the badminton from the shuttlecock hitting device (SIBOASI badminton shuttle shooter) (speed about 150km/hour, 5 seconds) Interval) continuously hit at a distance of 50cm and 30 degrees Hit the racket and evaluate it by the number of times the string is cut.

<tension loss>

In the case of badminton strings, a 25-pound load is applied to secure both ends. The ratio of the stress (F) to the initial load (retention ratio) after one week of standing at room temperature was determined.

Tension retention rate (%) = (stress after placement F/25) × 100

<Sound evaluation>

Five grades were evaluated by four senior players. In the usual use of the racket and the tension pounds, the tester only changes the string for evaluation and performs in the form of an average.

5 clear and comfortable sound

4 a little comfortable to play

3 General (usually used string, the level of sounding under tension)

2 bad sound

1 The sound is obviously worse

(Examples 1 to 5)

The following steps are used to manufacture a string for badminton.

(1) core wire

As the core wire, a filament yarn (melting point 260 ° C, 342 pieces of total number, total fineness 2340 deci tex) of the trade name "Promilan" (nylon 66) manufactured by Toray Industries Co., Ltd. was used for Z twisting 200 times. Line made of /m.

(2) Hot-melt flat monofilament and winding step

A low-melting copolymerized nylon manufactured by Toray Industries, Inc., trade name "CM8000" (melting point: 137 ° C) was used, and a flat monofilament having a shape in which five cross-sections were circularly joined as shown in Fig. 2A was produced by melt spinning. The flatness L/D is about 5, L = 0.165 mm, D = 0.035 mm, and the fineness is 49 deci tex. One of the flat monofilaments was wound flat on the surface of the core wire under the conditions shown in Table 1. The weight of the wound monofilament and the area coverage of the monofilament relative to the surface of the core are shown in Table 1. (Here, the winding weight is actually measured, and the coverage ratio is calculated from the weight). The winder is attached to the core supply portion of the knitting machine, and is continuously wound and woven.

(3) Sheath plied yarn and weaving step

As the sheath plied yarn, nylon nylon 6 and nylon 66 copolymer nylon (manufactured by Mitsubishi Engineering Plastics Co., Ltd., trade name "2030J", nylon 6/66 = 95/5, melting point 215 ° C) was used and made by melt spinning. A monofilament of a cross-sectional shape formed by a circle. The flatness L/D is about 4, L = 0.04 mm, D = 0.16 mm, the fineness is 64 deci tex, the strength is 4.8 N, and the elongation is 31.5%. A total of 16 sheets of the monofilaments were used, and the surface of the core wire in which the flat monofilament was wound flat was woven (woven) by a 16-mesh knitting machine. The physical properties of the braided wire are shown in Table 1.

(4) Heat followed by steps

The woven tape was subjected to heat treatment by a hot air drying device at a temperature of 215 ° C for 40 seconds. The extension ratio is set to 1.03. By this heat treatment, the low-melting flat monofilament is melted, and the core wire and the sheath plied strand are thermally joined and integrated. Also, the fusion of the sheath plied strands (sheaths) can be seen. The physical properties after the heat treatment are shown in Table 1. The increase in strength and the decrease in elongation can be seen by heat treatment.

(5) Surface resin layer forming step

The heat-treated belt was immersed once in a nylon 46 phenol solution, and dried at 90 ° C to obtain a string for badminton. An exploded perspective view of the obtained string is shown in Fig. 1. Among them, in order to make the structure easy to understand, the core state of the figure shows the winding state before the heat treatment.

(Comparative Example 1)

A comparative string was produced under the same conditions as in Example 1 except that the low-melting-point monofilament was not wound around the core wire in Example 1. The evaluation results of the products are shown in Table 2. Durability, tension retention, and sounding were inferior to those of Example 1.

(Comparative Example 2)

The core wire is changed into the flat monofilament of the above embodiment, and 5 single yarns of the same resin are 10d. The circular cross-section filaments were wound and wound under the same core winding conditions as in Example 1, and the strings were produced under the same conditions. The results are shown in Table 2. Compared with Example 1, durability, tension retention, and sounding were inferior. Further, the filaments of the five winding wires are not necessarily arranged in a flat shape of one layer, and a multilayer portion or a twist can be seen.

(Comparative Example 3)

The coiled wire was wound in the same manner as in Example 1 using a commercially available low melting point heat followed by a polyamide yarn multifilament yarn (manufactured by Fujisei Co., Ltd., trade name "Joiner" 50T-10f, melting point: 130 ° C), and was produced under the same conditions. String. The results are shown in Table 2. Durability, tension maintenance, and sounding were inferior to those of Example 1.

(Comparative Example 4)

The braided wire of the same manner as in Example 4 was subjected to a heat treatment at 130 ° C lower than the melting point of the flat monofilament wound around the core, and a string was produced under the same conditions. The results are shown in Table 2. If the string is disassembled and observed, the core monofilament is easily loosened, and almost no heat is observed. The durability of the strings, especially the orthogonal friction, is a lower result.

(Example 6)

Prior to the heat treatment step, the same string as in Example 4 was used, and a string was produced using a nylon 610 phenol solution as a surface resin working solution. The product evaluation results are shown in Table 1. The product evaluation results were as good as in Example 4.

(Example 7)

Using a low melting point nylon manufactured by Ube Industries Co., Ltd., trade name "7128B" (nylon 6/12 = 40/60; melting point 130 ° C), the shape of the five cross-sections as shown in Fig. 2A is formed by melt spinning. Flat monofilament. The flatness L/D is about 5, L = 0.165 mm, D = 0.035 mm, and the fineness is 51 deci tex. One of the flat monofilaments was wound flat on the surface of the core wire under the same conditions as in Example 4. The weight of the wound monofilament and the area coverage of the monofilament with respect to the surface of the core are shown in Table 1. As the sheath strand, nylon 6 is used as 75% and nylon 6/66 copolymerized nylon (Mitsubishi) Engineering Plastics Co., Ltd., trade name "2430J" nylon 6/66 = 80/20; melting point 190 ° C) is a 25% blended resin and melt-spun to form four cross-sectional monofilaments. The flatness L/D is about 4, D = 0.04 mm, L = 0.15 mm, the fineness is 62 deci tex, the strength is 4.9 N, and the elongation is 29.9%. A total of 16 filaments were used as the plied yarn, and the surface of the core wire of the flat monofilament was wound flat by a 16-mesh knitting machine to be woven (woven). The physical properties of the braided wire are shown in Table 1. The woven tape was heat-treated by passing through a hot air drying apparatus at a temperature of 220 ° C for 40 seconds. The stretching ratio was set to 1.02. By this heat treatment, the core wire and the sheath plied strand are thermally joined and integrated. Also, the fusion of the sheath can be seen. The physical properties after the heat treatment are shown in Table 1. The surface was coated with a nylon 46 solution as the surface resin in the same manner as in Example 4 to prepare a badminton string.

The evaluation results of the badminton strings of the above respective examples and comparative examples are shown in Tables 1 to 2. The statements in Tables 1 to 2 are as follows.

(1) "Leather line" is a sheath joint line.

Leather line S-1: N6/66 copolymer, 4 round cross-section monofilaments

Leather line S-2: N6 (manufactured by Mitsubishi Engineering Plastics Co., Ltd., "1035") 75wt%, N6/66=80/20 copolymer (Mitsubishi Engineering Plastics Co., Ltd., "2430J": melting point 190 °C) 25wt% blending, 4 Single cross section

(2) The "core wire" is a hot-melt flat monofilament.

M-1: low melting point nylon copolymer, 5 round cross-section monofilaments

M-2: low melting point nylon copolymer (N6/12=40/60, manufactured by Ube Nylon Co., Ltd., "7128B", melting point 130 °C), 5 circular cross-section monofilaments

M-3: 10 round cross-section filament single yarn 10 deci tex yarn

M-4: Multifilament, manufactured by Fuji Textile Co., Ltd., "Joiner" 50T-10f (low melting point nylon 130 ° C)

(3) The "low melting point component" is a low melting point hot melt flat monofilament resin component wound around a core. The component contained in the string is the amount of core resin (g/m) in the table divided by the weight per unit (g/m) of the product. Calculate the value obtained. However, the elongation in the longitudinal direction is about 3%, and thus is not considered.

(4) Evaluation criteria for melting of the core wire

A: Fully melted.

B: Melt but insufficient is seen.

C: No melting is seen.

(5) Surface resin processing

N46 resin: 18wt% nylon/phenol solution

N610 resin: 18wt% nylon/phenol solution

From the above, the following cases are known.

(1) Examples 1 to 7 are superior in durability, tension retention, and sound recording as compared with Comparative Example 1. The reason for this is that in the first embodiment, the low-melting flat monofilament is wound around the core wire, and the flat monofilament is melted by heating to thermally and integrally integrate the core wire and the sheath plied strand. In Comparative Example 1, the above flat monofilament was not used.

(2) Examples 1 to 7 are superior in durability, tension retention, and sounding as compared with Comparative Examples 2 to 3. The reason for this is that Comparative Examples 2 to 3 are obtained by winding the circular cross-section filaments instead of the flat monofilaments, but are not arranged in a flat shape.

(3) Examples 1 to 7 are superior in durability, tension retention, and sound recording as compared with Comparative Example 4. This is because the comparative example 4 does not thermally fuse the flat monofilament, and thus the integration of the core wire and the sheath plied wire cannot be achieved.

(4) It can be confirmed that the first to seventh embodiments are those in which the tension loss is small when the string is placed on the racket, and the string for the racket which is relatively hard to be hit and comfortable to play and which is highly durable can be obtained when playing.

[Industrial availability]

The string of the present invention is suitable for badminton, but is also useful for rackets such as hard tennis, soft tennis, squash, and the like.

1‧‧‧racing string

2‧‧‧core

3‧‧‧flat monofilament

4‧‧‧ sheath joint line

5‧‧‧Surface resin layer

Claims (15)

A racket string for a racket comprising a core wire, a sheath plied yarn on the outer side of the core wire, and a tape type of a surface resin layer on the outer side of the sheath plied wire, characterized in that the core wire is wound flatly There is a hot-melt flat monofilament, and the core wire and the sheath plied wire are thermally integrated. The racquet string of claim 1, wherein the ratio of the flat monofilament is 2 to 12% by weight of the string weight. The racquet string according to the first aspect of the patent application, wherein the outer sheath portion of the strand is also fused to each other by the melting of the flat monofilament. The racquet string of claim 1, wherein the melting point of the core wire, the sheath plied wire and the flat monofilament is represented by the following formula: TM3 < TM2 ≦ TM1 wherein TM1: melting point of the core wire, TM2 : the melting point of the sheath strand, TM3: the melting point of the flat monofilament. The racquet string according to claim 1, wherein the flat monofilament is at least one selected from the group consisting of a plurality of cross-sectional circles connected in a row shape, and a plurality of cross-sectional circular links. The surface has a smooth surface and a long round shape. For example, the racquet string of the first application of the patent scope, wherein the flat monofilament has a thickness of 0.015 to 0.06 mm and a flatness (width/thickness) of 1.5 to 100. The racquet string according to the first aspect of the invention, wherein the flat monofilament wound around the core wire has a coverage ratio of 15 to 70% with respect to the surface of the core wire. A string for a racket according to claim 1 of the patent scope, wherein the flat monofilament is not twisted Winding on the surface of the core wire. For example, in the racquet string of claim 1, wherein the core wire is a multifilament, and the single yarn fineness of the sheath plied yarn is thicker than the single yarn fineness of the multifilament of the core wire, and is 1 monofilament or 2 ~4 filaments of monofilament yarn. For example, in the racquet string of claim 1, the single yarn of the flat monofilament has a fineness of 10 to 150 deci tex. A method for producing a racquet string, which comprises a core wire, a sheath plied yarn on the outer side of the core wire, and a racquet string for a tape type of a surface resin layer on the outer side of the sheath plied wire, A flat-shaped monofilament of a hot-melt type is wound flat on the core wire, and a sheath plied yarn is knitted on the surface thereof, and the obtained braided wire is heated to a temperature higher than a melting point of the flat monofilament, so that the The flat monofilament is melted, and the core wire and the sheath plied strand are thermally and then integrated, and thereafter, a surface resin layer is formed on the outer side of the sheath plied strand. The method for manufacturing a string for racket according to claim 11, wherein the heat is subsequently subjected to a temperature of TM3+30° C. or higher and TM2+15° C. or less, so that the core wire and the sheath plied strand are thermally followed and the The sheath plied strands are partially fused to each other. The method for manufacturing a string for a racket according to claim 11, wherein the stretching ratio of the braided wire is 0.95 to 1.20 times. The method for manufacturing a string for a racket according to the eleventh aspect of the invention, wherein the flat monofilament has a thickness of 0.015 to 0.06 mm and a flatness (width/thickness) of 1.5 to 100. The method for manufacturing a string for a racket according to claim 11 of the patent application, wherein the core is wound around the core The coverage of the flat monofilament of the wire with respect to the surface of the core wire is 15 to 70%, and the flat monofilament is wound around the surface of the core wire without being twisted.