JP5593005B1 - Racket string and manufacturing method thereof - Google Patents

Abstract

Provided is a highly durable racket string in which a relatively hard feel and a comfortable hitting sound can be obtained and tension loss is small.
A string for a racket according to the present invention is a string of a braid type including (1), a core thread (2), an outer sheath braid (4), and an outer surface resin layer (5), A hot-melt flat monofilament (3) is wound flatly around the core yarn (2), and the core yarn (2) and the sheath braid (4) are integrated by thermal bonding. The string is produced by wrapping a hot melt flat monofilament (3) around the core yarn (2) flatly, stringing the sheath braid (4) on the surface, and using the obtained string yarn. The flat monofilament (3) is heated to a temperature equal to or higher than the melting point, the flat monofilament (3) is melted, and the core yarn (2) and the sheath braid (4) are integrated by thermal bonding.
[Selection] Figure 1

Description

  The present invention relates to a synthetic string for rackets such as badminton, tennis and squash. In particular, the present invention relates to a string for a racket that has a hard hitting feeling suitable for badminton, a comfortable hitting sound, low tension loss, and high durability.

  Conventionally, as a synthetic string for rackets such as tennis, badminton, squash and the like, many strings or braided strings made by winding the outside of a monofilament or multifilament as a core with a thin monofilament have been proposed. For example, in a badminton string, a string in which thin monofilaments having a diameter of about 0.06 mm are braided (made of string) as a multi-filament core is generally used. Thin strings generally have a problem that they are excellent in feel and sound but inferior in durability, and development of a string that satisfies both is desired.

  Patent Document 1 proposes coating the core yarn with a copolymerized thermoplastic resin solution. In Patent Document 2, it is proposed that a material having a melting point lower than that of the core material is used as a sheath and melted and bonded. In Patent Document 3, it is proposed that the sheath is melt-coated after the core resin is melt-coated with an adhesive resin and heat-sealed.

JP 2005-304678 A Japanese Utility Model Publication No. 60-86598 (full application specification No. 59-120410) JP 2007-177355 A

  However, the method of Patent Document 1 for processing a solution obtained by dissolving an adhesive resin in a solvent has a problem in terms of environment because it uses a solvent, and it is necessary to select a solvent that does not dissolve the core yarn fiber. Is limited. Furthermore, there is a problem that the concentration and viscosity of the resin during processing are likely to change due to temperature change, solvent volatilization, etc., and quality variations tend to occur. Further, when the core yarn is a multifilament, the resin liquid enters the inside of the core yarn structure, so that there is a problem that the surface resin amount is reduced. The thermal fusion method of Patent Document 2 has a merit that no solvent is used, but there is a description that a preferable amount of resin used is 25% by weight or more of the string. When used in such a large amount, the string diameter becomes thick, and the adhesive resin hardly contributes to the strength, so that it is difficult to obtain a thin and high-strength string, and the hitting feeling and sound are also deteriorated. . Patent Document 3 discloses that a resin is melt-coated on a core yarn, but it is technically difficult to perform a thin and uniform melt coating on the surface of a thin core, and when the coating amount is excessive, Similar to Patent Document 2, the diameter of the string obtained is large, and there is a problem of deteriorating the hit feeling.

  In order to solve the above-mentioned conventional problems, the present invention provides a highly durable racket string that provides a relatively hard feel and a comfortable hitting sound, and has a small tension loss.

  The racket string of the present invention is a braided string racket string including a core yarn, a sheath braid outside the core yarn, and a surface resin layer outside the sheath braid, and the core yarn Is characterized in that a hot-melt flat monofilament is wound flatly and the core yarn and the sheath braid are integrated by thermal bonding.

  The manufacturing method of the string for rackets of this invention is a manufacturing method of the string for rackets of the braid type | mold containing the core yarn, the sheath part assembly yarn of the outer side of the said core yarn, and the surface resin layer of the outer side of the said sheath part assembly yarn. Then, a hot melt flat monofilament is wound flatly around the core yarn, a sheath braid is formed on the surface thereof, and the obtained string is heated to a temperature equal to or higher than the melting point of the flat monofilament. The flat monofilament is melted to thermally bond and integrate the core yarn and the sheath portion assembled yarn, and then a surface resin layer is formed on the outside of the sheath portion assembled yarn.

  The present invention includes a core yarn, an outer sheath braid and an outer surface resin layer, and a hot melt flat monofilament is wound flatly around the core yarn, and the core yarn and the sheath braid , The tension loss when the string is stretched to the racket is small, a relatively hard feel and a comfortable hitting sound can be obtained at the time of hitting the ball, and a highly durable racket string can be provided. .

FIG. 1 is an exploded perspective view of a racket string in one embodiment of the present invention. 2A-C are cross-sectional views of a flat monofilament in one embodiment of the present invention. FIG. 3 is a schematic explanatory view of the orthogonal friction test apparatus used in the embodiment of the present invention.

  The inventors of the present invention have focused on minimizing the amount of resin used while maintaining adhesiveness for the melt bonding method that does not use a solvent. A thin hot melt type flat monofilament is wound and covered flatly, and the flat monofilament is heated and melted to integrate the core yarn and the sheath braid by heat bonding. Invented. More preferably, in order to improve the adhesion between the sheath braids, the fiber surface of the sheath braid is softened and partially fused to each other by raising the heat fusion temperature to the melting point range of the sheath braid. I also found out that it is important.

  The present invention relates to a braided string for a racket including a core yarn, an outer sheath braid of the core yarn, and a surface resin layer on the outer side, and a hot melt type flat monofilament is wound flatly around the core yarn, The yarn and the sheath braid are integrated by thermal bonding. The ratio of the flat monofilament is preferably in the range of 2 to 12% by weight when the string weight is 100% by weight. More preferably, it is 2.5 to 8% by weight. If it is the said range, a thin and highly powerful string can be obtained.

  In the present invention, it is preferable that, in addition to the thermal bonding and integration of the core yarn and the sheath braid, the outer sheath braid is also partially fused to each other by melting the flat monofilament. As a result, the sheath braids are also bonded to each other, so that the hitting sound and the durability can be improved.

The melting points of the core yarn, the sheath braid and the flat monofilament are preferably represented by the following formula. With the following formula, it is possible to prevent a decrease in strength of the core yarn and the sheath braid when the flat monofilament is thermally melted, and to obtain a thin and high-strength string.
TM3 <TM2 ≦ TM1
However, TM1: melting point of core yarn, TM2: melting point of sheath braid, TM3: melting point of flat monofilament.

  In the production method of the present invention, a hot-melt type flat monofilament is wound flatly around a core yarn, a sheath braid is formed on the surface thereof, and the obtained string is used as a melting point (TM3) or higher of the flat monofilament. The core yarn and the sheath braid are integrated by thermal bonding by melting the flat monofilament. The temperature for thermal bonding is preferably TM3 + 30 ° C. or higher and TM2 + 15 ° C. or lower. More preferably, the temperature is TM3 + 40 ° C. or higher and TM2 + 10 ° C. or lower. If it is the said range, a core thread and a sheath part braid can be heat-bonded, and also a sheath part braid can be partly melted.

  The draw ratio of the string yarn at the time of heat bonding is preferably 0.95 to 1.20 times. A more preferable draw ratio is 1.00 to 1.10. When heat-bonding at the above draw ratio, heat shrinkage can be prevented under tension, and a thin and high-strength string can be obtained.

  The thickness of the flat monofilament is preferably 0.015 to 0.06 mm, more preferably 0.02 to 0.05 mm. The flatness (width / thickness) of the flat monofilament is preferably 1.5 to 100, and more preferably 2.5 to 80. If the thickness and flatness of the flat monofilament are within the above ranges, the core yarn and the sheath braid can be thermally bonded and the sheath braid can be partially fused.

In order to flatly wrap a flat monofilament around the surface of the core yarn, the following cautions are necessary.
(1) When producing a flat monofilament, it is wound without being twisted with a horizontal winder, and when it is wound around a core yarn, it is pulled out from the horizontal wound body so that no twist is generated.
(2) When a flat monofilament is manufactured, if it is wound by a vertical winder, the winding is twisted, and when winding around the core yarn, it is pulled out from the wound body in the same direction and no twisting is entered. Like that.

  The coverage of the flat monofilament wound around the core yarn on the surface of the core yarn is preferably 15 to 70%, more preferably 20 to 50%. Within this range, the core yarn and the sheath braid can be thermally bonded and the sheath braid can be partially fused.

  The cross-sectional shape of the flat monofilament wound around the core yarn is preferably a flat shape having irregularities. If the cross-sectional shape is uneven, when the sheath monofilament is laced from the flat monofilament wrapped around the core yarn, friction can be generated to produce a strong string, and the adhesive strength can be increased with a small amount. is there.

  The core yarn material is not particularly limited, but is preferably a high-strength polyamide filament yarn. Polyamides include aliphatic polyamide resins such as nylon 6, nylon 66, nylon 610, nylon 612, nylon 46, nylon 56, nylon 410, nylon 12, and semi-aromatic polyamide resins such as nylon 9T, nylon MXD6, and nylon 6T. Is mentioned. Particularly preferred are high-strength multifilament yarns of nylon 6 and nylon 66. High-strength polyamide yarns are generally known for industrial materials such as tire cords.

  The preferred single yarn fineness of the core yarn is 2 to 10 deci tex, and the total fineness is 1500 to 7000 deci tex. The preferred number of filaments constituting the core yarn is 150-3500.

  When the melting point of the core yarn is TM1, TM1 is preferably 170 ° C. or higher, more preferably 200 ° C. or higher. In the present invention, the melting point is a value indicated by a peak temperature when measured with a differential scanning calorimeter (DSC) at a heating rate of 20 ° C./min. The physical properties of the core yarn greatly affect the physical properties of the string. A preferred multifilament has a strength of 5.0 to 12.0 cN / decitex and an elongation of 16 to 25%. The core yarn can be used together or mixed with other filaments as required.

  The core yarn is preferably twisted and used from the standpoints of filament bundle convergence, roundness, elongation, and the like, and the number of twists is preferably about 30 to 300 times / m. Resin processing may be performed with an adhesive resin in order to enhance the adhesion between the core yarns and to impart an appropriate hardness to the core yarns. Moreover, a low-melting-point heat-adhesive fiber can be mixed with the core yarn.

  As the sheath braid (melting point: TM2), a filament made of a resin having a melting point which is preferably the same as or lower than the melting point of the core yarn and higher than the low melting point resin wound around the core is used. As the material, the same polyamide-based resin as that of the core yarn is preferably exemplified. Examples thereof include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 612, nylon 46, nylon 56, nylon 410, nylon 11, and nylon 12. These copolyamides are preferably used. When the core yarn component is nylon 66 or nylon 6, nylon 6, nylon 6/66 copolymer, nylon 6/12 copolymer or the like is used as a preferable sheath braid. Moreover, the filament which blended about 5 to 80% of copolymer nylon with low melting | fusing point to nylon 6 may be sufficient.

  As the sheath braiding yarn, those having a single yarn fineness larger than the single yarn fineness of the multifilament of the core yarn are preferable, and it is preferable to use one monofilament or a filament in which about 2 to 4 monofilaments are arranged as the braid. When the single yarn fineness is too thick or the number of filaments is too large, the diameter after stringing becomes large, which is not preferable. Moreover, the cross-sectional shape of a filament can use an ellipse or a flat cross section. A connected cross-sectional filament disclosed in Japanese Patent Application Laid-Open No. 2008-48867 filed by the present applicant is also preferably used. The preferred single yarn fineness of the sheath braid is about 10 to 100 deci tex. It is preferable to use 8 to 32 braided yarns of this single yarn fineness to form a sheath to form a sheath.

  A hot melt type flat monofilament is wound flatly around the outside of the core yarn, and then a sheath braid is made. A known method can be adopted for the string making. For example, it is preferable to use a 16-placing machine. The step of winding the flat monofilament and the step of forming the sheath braiding may be separate steps or may be continued.

  As the hot-melt flat monofilament, a material having a lower melting point than that of the filament fiber of the core yarn and the sheath portion braid and having good adhesion to the constituent filament fiber of the core yarn and the sheath portion of the braid is preferably used. As a preferable melting point (TM3), a resin having a melting point of 100 ° C. to 180 ° C. and having a melting point lower than that of a resin of TM3 <TM2 ≦ TM1, that is, a core yarn fiber and a sheath braided fiber is selected. Examples of such resins include copolymerized polyamide resins and polyurethane resins obtained by copolymerizing two or more selected from aliphatic nylons such as nylon 6, nylon 66, nylon 12, nylon 11, nylon 610, and nylon 612. Can be mentioned. More preferably, the resin is lower by 30 ° C. or more than the melting point of the sheath braided 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 6/66/610/12 Nylon 6/66/610/612 copolymer and the like can be mentioned, but the copolymer is not limited to these, and can be appropriately selected from known copolymer nylon as a heat-fusible resin and a heat-fusible fiber.

  According to the study by the present inventors, in order to obtain a durable string even when the feel and sound are fine, the amount and the applied state of the adhesive component are important as described above, and sufficient adhesiveness is obtained. It is important to reduce the applied amount as much as possible while applying the. Therefore, in the present invention, a flat monofilament is used as the form of the material to be wound. In the case of a multi-fragment with a large number of filaments, it is difficult to uniformly control the thickness and width of the yarn in the wound state, and it is not preferable because a portion having a large string diameter or a void is formed.

  The preferred single yarn fineness of the flat monofilament is 10 to 150 deci tex. A more preferable single yarn fineness is 20 to 100 deci tex. One flat monofilament is preferably wound flatly around the core yarn, but a plurality of bobbins may be used for winding.

  After melting the flat monofilament, the core yarn and the sheath braid are heat-bonded and integrated, and then a surface resin layer is formed outside the sheath braid. The surface resin layer is formed by dipping or melt coating a nylon resin dissolved in a solvent. Nylon resin is not particularly limited, but aliphatic polyamides such as nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11 and nylon 12, and their copolyamides and semi-aromatic polyamides such as nylon 9T can be used. . Dipping or coating can improve color, appearance, durability, and the like. Furthermore, coloring, heat treatment, printing, oiling and the like can be performed as necessary.

  Next, it demonstrates using drawing. FIG. 1 is an exploded perspective view of a racket string 1 according to an embodiment of the present invention. In this racket string 1, a hot melt flat monofilament 3 is wound flatly around a core yarn 2, and the core yarn 2 and the sheath braid 4 are integrated by thermal bonding (the figure is 3 for the sake of clarity). The flat monofilament of Fig. 2 illustrates the shape before melting). A surface resin layer 5 is formed on the surface of the sheath braid 4. In FIG. 1, the core yarn 2 is an example of a multifilament, but it may be a monofilament. The number of multifilaments can also be arbitrarily selected. Moreover, although the sheath part braiding yarn 4 showed the example of the 4-connection monofilament with a circular cross section, 2-8 connection may be sufficient. Alternatively, 2 to 4 monofilaments may be arranged in parallel.

  In the present invention, the flat monofilament is preferably at least one selected from a shape in which a plurality of cross-sectional circles are connected in a row, a concavo-convex shape in which a plurality of cross-sectional circles are connected and the surface is smooth, and an oval shape. For example, the cross-sectional shape shown in FIGS. FIG. 2A shows a flat monofilament 6 having five cross-sectional circles connected, and the flatness L / D is about 5. FIG. However, L shows a width | variety and D shows thickness. For example, L = 0.165 mm and D = 0.035 mm. FIG. 2B shows a flat monofilament 7 having an uneven surface. FIG. 2C shows an oblong flat monofilament 8 having no irregularities on the surface.

  This will be specifically described below with reference to examples. In addition, this invention is not limited to the following Example. In the following Examples, monofilaments and strings were evaluated by the following methods.

<Physical property test>
Strength, knot strength, and elongation were in accordance with the measurement method of JIS L1013. The diameter was measured five times using a micrometer while rotating the monofilament little by little, and the average value was taken as the diameter.

<Repulsion / Rigidity>
In the case of a badminton string, one string is pulled with a tension of 20 pounds and clamped at both ends (grip spacing 30 cm). Using a pendulum hammer, swing down from a fixed position so that it strikes the center of the string at a right angle to the string in the horizontal direction, and the movement (displacement) and stress of the string after the collision are 1/1000 second intervals. The rigidity (pound / inch) and the rebound rate (%) were obtained by the following calculation method.
Rigidity = Maximum stress P (pound) / Maximum horizontal displacement L (inch)
Rebound rate (%) = (S2 / S1) × 100
S1: Area of the portion from the collision to the maximum displacement (forward portion) in the stress-strain (displacement) curve (reciprocating) S2: Area stiffness value from the maximum displacement position to the zero displacement (return portion) of the stress-strain curve The higher the value, the harder it is on the racket, and the lower the value, the softer.
The higher the rebound rate, the less energy loss in collision and the greater the rebound (Reference: Rod Cross “Laboratory testing of tennis string” Sports Engineering (2000) 3, 219-230).

<Durability 1> Orthogonal friction An orthogonal friction test apparatus 10 shown in FIG. Both ends of the string 11 were fixed in the horizontal direction of the arrow P with a tension of 30 pounds applied (13a, 13b). The same string 12 crossed the string 11 in the horizontal direction at right angles, one end 12a was fixed, and the other end 12b was hung with a load 14 of 2 kg. The string 12 is hung at a right angle on the same horizontal plane on the string 11 with both ends fixed, and is pulled downward in the vertical direction by the weight of the load. With the load applied to the string 12, as shown by the arrow Q, the string 12 was reciprocated 10 mm at a speed of 1 reciprocation per second in the direction perpendicular to the horizontal. Evaluation was performed in the state of fluff of the string 12 after reciprocating friction. The number of times that the string (12) was cut or fluffed was evaluated. When the fluff is small after 200 times of friction, it was set to 200 times or more.

<Durability 2> Durability test by shuttle hitting A string lifted on a racket at 25 pounds, and a shuttle (speed approximately 150km / h, every 5 seconds) launched from a shuttlecock launcher (SIBOASI shuttlecock shooter) The racket was continuously hit at a distance of 50 cm and an angle of 30 degrees, and the number of times the string was cut was evaluated.

<Tension loss>
For badminton strings, load 25 pounds and fix both ends. The ratio (retention rate) to the initial load of stress (F) after standing at room temperature for 1 week was determined.
Tension retention ratio (%) = (stress after standing F / 25) × 100

<Rating sound evaluation>
A five-level evaluation was conducted by four senior players. It was evaluated by switching only the string with the racket and tension pound that the test batter usually uses, and expressed as an average.
5 Clearly comfortable sound 4 Slightly comfortable sound 3 Normal (Rounded sound level under normal strings and tension)
2 The sound is slightly bad 1 The sound is clearly bad

(Examples 1-5)
The badminton string was manufactured in the next step.
(1) Core Yarn Y-twisted 200 times / m of filament yarn (melting point 260 ° C., number of components 342, total fineness 2340 deci tex) manufactured by Toray Industries, Inc., as the core yarn It was used.
(2) Hot-melt flat monofilament and winding process Toray's low melting point copolymer nylon, trade name “CM8000” (melting point 137 ° C.) is used to form a shape in which five cross-sectional circles are connected as shown in FIG. 2A. A flat monofilament was prepared by melt spinning. The flatness L / D was about 5, L = 0.165 mm, D = 0.035 mm, and the fineness was 49 deci tex. One flat monofilament was wound flatly on the surface of the core yarn under the conditions shown in Table 1 while changing the number of windings. The weight of the wound monofilament and the area coverage of the monofilament on the surface of the core yarn are shown in Table 1 (here, the wound weight was measured and the coverage was calculated from the weight). The winding machine was attached to the core yarn supply part of the string making machine, and the winding and string making were continuously performed.
(3) Sheath braiding and string making process As sheath braiding, nylon 6 and nylon 66 copolymer nylon (Mitsubishi Engineering Plastics, trade name “2030J”, nylon 6/66 = 95/5; melting point 215 ° C. ) Was used to produce a monofilament having a cross-sectional shape in which four circles were connected by melt spinning. The flatness L / D was about 4, L = 0.04 mm, D = 0.16 mm, the fineness was 64 deci tex, the strength was 4.8 N, and the elongation was 31.5%. A total of 16 monofilaments were used one by one, and the flat monofilament was braided (stitched) on the surface of the core yarn that was flatly wound with a 16-placing machine. Table 1 shows the physical properties of the string yarn.
(4) Thermal bonding process The string after the string making was passed through a hot air drying apparatus having a temperature of 215 ° C. for 40 seconds and heat-treated. The draw ratio was 1.03. By this heat treatment, the low melting point flat monofilament was melted, and the core yarn and the sheath braid were thermally bonded and integrated. In addition, fusion of the sheath braid (leather thread) was also observed. Table 1 shows the physical properties after the heat treatment. Increase in strength and decrease in elongation were observed by heat treatment.
(5) Surface resin layer forming step The string after the thermal bonding was dipped 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. However, for easy understanding of the structure, the core winding state in 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 yarn in Example 1. The evaluation results of the products are shown in Table 2. Compared to Example 1, durability, tension retention, and hitting sound were inferior.

(Comparative Example 2)
The core wound yarn was changed to the flat monofilament of the above example, and five round cross-section filaments of the same single yarn 10d of the same resin were aligned, wound under the same core winding conditions as in Example 1, and the other conditions were the same. . The results are shown in Table 2. Compared to Example 1, durability, tension retention, and hitting sound were inferior. Further, the five filaments of the wound yarn were not necessarily arranged in a flat shape of one layer, and a multilayer portion and kinking were recognized.

(Comparative Example 3)
A commercially available low-melting-point heat-bonding polyamide multifilament yarn (Fujibo Co., Ltd., trade name “JOINER” 50T-10f, melting point 130 ° C.) was wound around the core winding yarn in the same manner as in Example 1, and the other conditions were the same. did. The results are shown in Table 2. Compared to Example 1, durability, tension maintenance, and hitting sound were inferior.

(Comparative Example 4)
A string was produced under the same conditions except that the same string yarn as in Example 4 was heat-treated at 130 ° C. lower than the melting point of the flat monofilament wound around the core. The results are shown in Table 2. When the string was disassembled, the core-wound monofilament was easily unwound and almost no thermal bonding was observed. The durability of the string, especially the orthogonal friction, was low.

(Example 6)
Up to the heat treatment step, the same string as in Example 4 was used, and a string was prepared using a nylon 610 phenol solution as the surface resin processing solution. The product evaluation results are shown in Table 1. The product evaluation results were as good as in Example 4.

(Example 7)
Melting flat monofilament with 5 cross-section circles as shown in Fig. 2A using low-melting nylon, trade name "7128B" (nylon 6/12 = 40/60; melting point 130 ° C), manufactured by Ube Industries, Ltd. Made by spinning. The flatness L / D was about 5, L = 0.165 mm, D = 0.035 mm, and the fineness was 51 deci tex. One flat monofilament was wound flatly around the core yarn surface under the same conditions as in Example 4. Table 1 shows the weight of the wound monofilament and the area coverage of the monofilament on the core yarn surface. Copolymer nylon of 75% nylon 6 and nylon 6/66 (Mitsubishi Engineering Plastics Co., Ltd., trade name “2430J” nylon 6/66 = 80/20; melting point 190 ° C.) 25% blend resin is used as the sheath braid. Then, a monofilament having a cross-sectional shape in which four circles are connected was melt-spun and prepared. The flatness L / D was about 4, D = 0.04 mm, L = 0.15 mm, the fineness was 62 deci tex, the strength was 4.9 N, and the elongation was 29.9%. A total of 16 monofilaments were used as a braid, and the braided machine was braided (stitched) on the surface of the core yarn obtained by winding the flat monofilament flatly with a 16-placing machine. Table 1 shows the physical properties of the string yarn. The string after the string making was passed through a hot air drying apparatus having a temperature of 220 ° C. for 40 seconds and heat-treated. The draw ratio was 1.02. By this heat treatment, the core yarn and the sheath braid were thermally bonded and integrated. In addition, fusion of leather was observed. Table 1 shows the physical properties after the heat treatment. The surface resin was coated with the same nylon 46 solution as in Example 4 to prepare a badminton string.

Tables 1 and 2 show the evaluation results of the badminton strings of the above examples and comparative examples. Explanations of terms in Tables 1 and 2 are as follows.
(1) “Skin” refers to sheath braiding.
Leather S-1: N6 / 66 copolymer, circular cross-section 4-connected monofilament leather S-2: N6 (Mitsubishi Engineering Plastics, "1035") 75wt%, N6 / 66 = 80/20 copolymerization (Mitsubishi Engineering Plastics) "2430J": Melting point 190 ° C) 25wt% blend, circular cross-section 4-connected monofilament
(2) “Core wound yarn” is a hot-melt flat monofilament.
M-1: Low melting point nylon copolymer, 5 cross-section monofilaments
M-2: Low melting point nylon copolymer (N6 / 12 = 40/60, manufactured by Ube Nylon Co., "7128B", melting point 130 ° C)
M-3: Round cross section filament single yarn 10 deci tex, aligning 5
M-4: Multifilament, manufactured by Fujibo, "Joyner" 50T-10f (low-melting nylon 130 ° C)
(3) “Low melting point component” refers to a low melting point hot melt flat monofilament resin component wound around a core. The component% contained in the string is a numerical value calculated by dividing the amount of core winding resin (g / m) in the table by the product weight (g / m). However, since the elongation in the length direction is about 3%, it is not considered.
(4) Evaluation standard A of melting of core wound yarn: It is sufficiently melted.
B: Melting is seen but insufficient.
C: Melting is not recognized.
(5) Surface resin processing N46 resin: 18 wt% nylon / phenol solution N610 resin: 18 wt% nylon / phenol solution

From the above, we found the following.
(1) Examples 1 to 7 were superior to Comparative Example 1 in durability, tension retention, and hitting sound. This is because in Example 1, the low melting point flat monofilament was wound around the core yarn, and the flat monofilament was melted by heating to integrally bond the core yarn and the sheath braid. Is because the flat monofilament was not used.
(2) Examples 1 to 7 were superior in durability, tension retention, and hitting sound as compared with Comparative Examples 2 to 3. In Comparative Examples 2 to 3, the round monofilaments were aligned and wound instead of the flat monofilaments, but they were not arranged in a flat shape.
(3) Examples 1-7 were superior to Comparative Example 4 in durability, tension retention, and sound. In Comparative Example 4, since the flat monofilament was not heat-sealed, the core yarn and the sheath braid could not be integrated.
(4) Examples 1 to 7 are highly durable racket strings that have a small tension loss when the string is stretched on the racket, provide a relatively hard feel and a comfortable hitting sound when hitting the ball, and are highly durable. Was confirmed.

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

DESCRIPTION OF SYMBOLS 1 String for rackets 2 Core yarn 3, 6, 7, 8 Flat monofilament 4 Sheath braiding 5 Surface resin layer 10 Orthogonal friction test apparatus 11, 12 String 13a, 13b, String fixing tool 14 Load

Claims (15)

A braided string for a racket including a core yarn, a sheath portion braid outside the core yarn, and a surface resin layer outside the sheath portion braid,
A racquet string, wherein a hot melt flat monofilament is wound flatly around the core yarn, and the core yarn and the sheath braid are integrated by thermal bonding.   The racket string according to claim 1, wherein a ratio of the flat monofilament is 2 to 12% by weight of the string weight. The fusion of the flat monofilament, in addition to heat bonding integration of the core yarn and the sheath braid, the outer sheath braid is also partly fused to each other. Racket string. 4. The racket string according to claim 1, wherein the melting points of the core yarn, the sheath braiding yarn, and the flat monofilament are represented by the following formula.
TM3 <TM2 ≦ TM1
However, TM1: melting point of core yarn, TM2: melting point of sheath braid, TM3: melting point of flat monofilament.   5. The flat monofilament is at least one selected from a shape in which a plurality of cross-sectional circles are connected in a row, a concavo-convex shape in which a plurality of cross-sectional circles are connected and the surface is smooth, and an oval shape. String for racket as described in.   The racket string according to any one of claims 1 to 5, 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 string for rackets according to any one of claims 1 to 6, wherein a covering ratio of the flat monofilament wound around the core yarn to the surface of the core yarn is 15 to 70%.   The racket string according to any one of claims 1 to 7, wherein the flat monofilament is wound around the surface of the core yarn without twisting. The core yarn is a multifilament, the single yarn fineness of the sheath yarn is larger than the single yarn fineness of the multifilament of the core yarn, and the sheath yarn is composed of one monofilament or 2 to 4 monofilaments. It is a filament, The string for rackets of any one of Claims 1-8.   The string for rackets according to any one of claims 1 to 9, wherein the monofilament fineness of the flat monofilament is in the range of 10 to 150 deci tex. A method for producing a string for a braided string racket including a core yarn, a sheath portion braid outside the core yarn, and a surface resin layer outside the sheath portion braid,
A hot melt flat monofilament is wound flatly around the core yarn,
Make a sheath braid on the surface,
The obtained string yarn is heated to a temperature equal to or higher than the melting point of the flat monofilament, the flat monofilament is melted, and the core yarn and the sheath braid are integrated by heat bonding,
Then, the manufacturing method of the string for rackets characterized by forming a surface resin layer in the outer side of the said sheath part braiding yarn. The racket string according to claim 11, wherein the temperature of the thermal bonding is TM3 + 30 ° C. or higher and TM2 + 15 ° C. or lower, the core yarn and the sheath braid are thermally bonded, and the sheath braid is partially fused. Production method.
However, TM2: melting point of sheath braid, TM3: melting point of flat monofilament.   The method for producing a string for a racket according to claim 11 or 12, wherein a draw ratio of the string yarn at the time of the thermal bonding is 0.95 to 1.20 times.   The method for producing a racket string according to any one of claims 11 to 13, 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 coverage with respect to the said core yarn surface of the flat monofilament wound around the said core yarn is 15 to 70%, The said flat monofilament is wound around the said core yarn surface without twisting. The manufacturing method of the string for rackets of Claim 1.

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