JP2795622B2 - Synthetic string and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket string (gut) for tennis, badminton, squash and the like.
About. More particularly, it relates to a string made of synthetic fiber and having a specific gravity.

[0002]

2. Description of the Related Art There are three functions required for a racket string: resilience, durability and stretchability.
The former two functions of synthetic strings have been developed and advanced with the goal of the performance of natural gut consisting mainly of cattle and sheep intestines.

[0003] As a result, these functions have now become possible to surpass those of natural gut.
That is, when high-elasticity / high-strength nylon fiber, aromatic polyamide fiber, polyphenylene sulfide (PPS) fiber, polyetheretherketone (PEEK) fiber, or the like is used, resilience is maintained at an elastic recovery rate, and durability is maintained at stress relaxation. Characteristics such as rate have come to surpass those of natural gut.

[0004] In terms of stretchability, the composite string is far superior to the conventional one. However, more than half of tennis professionals have been using synthetic strings recently, but still using natural gut.

It is considered that the cause of these is that natural gut has excellent sensory characteristics such as a hitting sound and a subtle hitting feeling in addition to the mechanical characteristics. Against this background, recent global trends in synthetic strings include smaller diameter, finer gauges. Conventionally, those having a diameter of 1.3 mm (16 gauge) or more were the mainstream, but recently, ones having a diameter of 1.22 to 1.24 mm have been used.
There is an increasing demand for 7 gauges and 18 gauges with a diameter of 1.06 to 16 mm.

[0006] Although the main purpose of these is to improve the resilience, it is also considered to be to supplement the above-mentioned sensory characteristics.

[0007]

However, the mere use of the conventional thin gauge has a disadvantage that the durability is reduced as a natural result. In addition, since the weight ratio occupied by the string decreases, the moment of inertia decreases, swingability, the weight of the entire racket, etc. change,
Increasingly moving away from the performance of natural gut. In addition, in the field of synthetic strings, improvement in hitting sound, which is an important factor for the exhilaration of sports, has been strongly demanded.

[0008] The present invention has been made in view of the above circumstances, and, of course, excellent repulsion and difficulty in sagging of natural gut, swinging of a racket, surface stability, weight feeling and the like. It is an object of the present invention to provide an inexpensive synthetic string that has a hitting feel and a pleasant hitting sound that are comparable in performance to a natural gut, have excellent water resistance, and are inexpensive.

[0009]

In order to achieve the above object, a synthetic string of the present invention is a string including a polyamide synthetic fiber and a fiber having a specific gravity larger than that of the polyamide synthetic fiber, wherein the string is The specific gravity D (measured at 25 ° C.) represented by the above formula (Equation 1) is 1.2.
It is in the range of 0 to 1.60.

In the above structure, it is preferable that the polyamide-based synthetic fiber is a main component of 50% by weight or more, and a fiber having a specific gravity higher than that of the polyamide-based synthetic fiber is a sub-component of less than 50% by weight.

In the above structure, the fiber having a specific gravity higher than that of the polyamide synthetic fiber is preferably made of a material having a specific gravity of 1.50 or more. Further, in the above configuration, it is preferable that the auxiliary component is a conjugate fiber obtained by compounding lead with polyamide fiber or a fiber of a polymer containing fluorine.

In the above structure, the conjugate fiber obtained by compounding lead with polyamide fiber is preferably a core-sheath conjugate fiber in which the outer component is polyamide and lead is present inside.

In the above structure, it is preferable that the synthetic string has a core-sheath structure including a fiber forming a core and a fiber forming a sheath. Further, in the above configuration, it is preferable that the core-sheath conjugate fiber in which lead is composited be present in the sheath portion of the string.

[0014] In the above structure, it is preferable that the fiber of the polymer containing fluorine is present in the core and / or the sheath of the string. Further, in the above configuration, it is preferable that the fibers constituting the synthetic string are braided or twisted.

[0015] In the above structure, the fibers constituting the synthetic string are preferably integrated by an adhesive. Next, the method for producing a synthetic string of the present invention uses a polyamide synthetic fiber as a core component, mixes a polyamide synthetic fiber with a fiber having a higher specific gravity than the polyamide synthetic fiber as a sheath component, and applies an adhesive. And then coated with a resin solution or a molten resin, dried or solidified, and then subjected to a stretching treatment for adjusting elongation. Then, a smoothing agent is applied and the specific gravity of the string (25 C.) 1.20 or more and 1.60.
It is characterized by the following range.

[0016]

According to the structure of the present invention, a string comprising a polyamide-based synthetic fiber and a fiber having a specific gravity larger than that of the polyamide-based synthetic fiber, wherein the string has a specific gravity D represented by the above formula (Equation 1) (Measured at 25 ° C.) in the range of 1.20 or more and 1.60 or less, it is obvious that natural gut has excellent resilience and resistance to loosening, and the racket swingability and surface stability (suite It has the same performance as a natural gut, such as a racket that does not shake even when hitting a spot other than a spot), a feeling of hitting such as a feeling of weight, a pleasant hitting sound,
Moreover, an inexpensive synthetic string having excellent water resistance can be realized. That is, the specific gravity of the polyamide at 25 ° C. is 1.12 to 1.14 for nylon 6, and 1.13 to 1.66 for nylon 6,6.
Since it is 1.15, the specific gravity of the entire string can be increased by mixing a considerable amount of fibers having a large specific gravity with respect to these polyamides. As a result, the resilience is close to that of a natural gut. Moreover, since the polyamide-based synthetic fiber is used, it is possible to realize an inexpensive synthetic string which is not loosened, has excellent water resistance, and is inexpensive. In the above, if the specific gravity of the string is less than 1.2, the shot feeling does not improve so much. On the other hand, when the specific gravity exceeds 1.6, it becomes too heavy, and the swing-out property is undesirably reduced.

In the above, the polyamide-based synthetic fiber is 5
When the fiber having a specific gravity of 0% by weight or more and a specific gravity larger than that of the polyamide-based synthetic fiber is a sub-component of less than 50% by weight, the durability and looseness of the polyamide-based synthetic fiber can be further maintained.

In the above, it is preferable that the fiber having a specific gravity higher than that of the polyamide-based synthetic fiber be made of a material having a specific gravity of 1.50 or more, because it is not necessary to increase the amount of the high specific gravity component so much.

In the above, if the auxiliary component is a conjugate fiber obtained by compounding lead with a polyamide fiber or a fiber of a polymer containing fluorine, the shot feeling can be further enhanced.

In the above, if the conjugate fiber obtained by compounding the lead with the polyamide fiber is a polyamide-sheath conjugate fiber in which the outer component is a polyamide and lead is present therein, peeling of the polyamide and the lead may occur. This is preferable because the integration can be maintained without any problem.

In the above, if the synthetic string has a core-sheath structure composed of fibers forming the core and fibers forming the sheath, the shot feeling can be further enhanced and the durability can be enhanced. In the above, the core-sheath conjugate fiber in which lead is compounded can maintain high strength when it is present in the sheath portion of the string. When a polymer fiber containing fluorine is used, it can be present at the core and / or the sheath of the string.

In the above, if the fibers constituting the synthetic string are braided or twisted, the integration can be strengthened. In the above, the fibers constituting the synthetic string are integrated by an adhesive, and the durability can be further improved.

Next, according to the method for producing a synthetic string of the present invention, a polyamide synthetic fiber is used as a core component, and a polyamide synthetic fiber and a fiber having a higher specific gravity than the polyamide synthetic fiber are mixed as a sheath component. Wrap around the core component while applying adhesive, then coat with a resin solution or molten resin, dry or solidify, stretch to adjust elongation, then apply a smoothing agent and string Specific gravity (measured at 25 ° C.) of 1.20 or more.
By setting the range to 60 or less, a string with the above-mentioned specific gravity adjusted can be efficiently and rationally manufactured.

[0024]

The present invention will be described more specifically with reference to the following examples. The present inventors paid attention to the view that the natural vibrations related to the hitting sound and the subtle hitting feeling are related to the linear density of the string, and investigated and studied the relationship between them in detail. In addition, the inventors conducted detailed research and development on the moment of inertia and the weight distribution of the racket as a measure of the ease of swinging the racket, and finally arrived at the present invention. As a result, in a string mainly composed of a polyamide-based synthetic fiber, a string is manufactured using a polyamide / lead composite fiber having a specific gravity of 1.50 or more, or a fiber of a polymer containing fluorine, and the string has a specific gravity of 1.20 to 1. When it is in the range of 60, it is found that excellent repulsion when using a natural gut, ease of sagging, of course, racket swinging ability, hitting feeling such as weight feeling, and pleasant hitting sound can be obtained. Reached the present invention.

The polyamide synthetic fiber used as the main component of the present invention is mainly a monofilament or multifilament of nylon 6, nylon 66, or a copolymerized nylon thereof, and is excellent in durability against repeated stretching, adhesion, strength and the like. Because it is, it is used favorably.

The typical polyethylene terephthalate fiber of polyester fiber is similar to that of natural gut in terms of specific gravity, but has a large stress relaxation under load, it is difficult to maintain tension at the time of tensioning, Large changes over time,
It cannot be used as a main component. Aromatic polyamides (for example, “Kevlar” and “Nomex” manufactured by DuPont) have a specific gravity of 1.44 to 1.45, but “Kevlar” has a low elongation of several percent, and “Nomex” has a low elongation. Is high but low in strength and does not meet the purpose of the present invention.

Next, polyamide / lead composite fibers are useful as composite components for adjusting the specific gravity coefficient. This is a composite spin of ordinary nylon and lead, in which lead is discontinuously present in the core and the sheath is formed of nylon 6. Although the specific gravity is adjusted by the amount of the composite, it is desirable that the specific gravity is in the range of about 1.50 to 3.00 from the viewpoint of the strength, handleability, and the like. Although this fiber has low strength, it has excellent adhesion with the main component, and high specific gravity can be easily obtained.
The specific gravity coefficient of the string can be adjusted, which is useful for the present invention. Because of its low strength, it is disadvantageous to use it for the core component, which is the main component of the string, and it is desirable to use it exclusively for the coating component.

Another useful composite component for adjusting the specific gravity coefficient is, as a fiber made of a polymer containing fluorine, a fiber made of a resin containing a fluorine atom in a molecule. Examples of these resins include polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (PF
A), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), and trifluoroethylene chloride (PC)
TFE) tetrafluoroethylene-ethylene copolymer (ET
FE), polyvinylidene fluoride (polyvinylidene fluoride, PVDF), polyvinyl fluoride (PVF), and the like. The specific gravity depends on the type of polymer, but is 1.70.
From about 2.20 can be selected. In the present invention, polyvinylidene fluoride is particularly useful from the viewpoint of the strength level. Therefore, polyvinylidene fluoride can be used for the core component which is a main component of the string,
Fibers made of other fluorine-containing polymers are disadvantageous,
It is desirable to use it as a coating component.

The string is manufactured by using the main component and the composite component for adjusting the specific gravity coefficient by the following process as an example. A polyamide monofilament having a core component as a core component, and a regular polyamide monofilament as a coating component and a composite component having a specific gravity of 1.50 or more, such as a polyamide / lead composite fiber or a fluorine-containing polymer fiber, on its outer peripheral surface. And winding while applying an adhesive. From the specific gravity defined in the present invention, the mixing ratio is 50% by weight of the sheath component.
Obtained in the degree. This ratio is also favorable from the viewpoint of adhesiveness to the core component.

When polyvinylidene fluoride fibers are used as the core component, it is preferable to make the coating component larger in composition ratio than usual because the adhesion of the fibers is extremely low. For example, when the coating component is a polyamide monofilament,
Normally, one turn can secure sufficient durability, but in the case of the present invention, two turns are desirable. When the coating component is a polyamide multifilament, it is desirable to use a filament having a relatively high denier of 500 denier or more.

Next, it is processed or coated with a resin solution or a molten resin. The resin to be used is preferably polyamide or polyurethane from the viewpoint of water resistance and durability. Finally, a stretching treatment is performed to adjust the elongation, and a smoothing agent such as paraffin or silicone oil is applied to finish the string.

The most important thing in the present invention is to adjust the string specific gravity in the range of 1.2 to 1.6. This value is around 1.11 for ordinary strings made of polyamide, but when it is 1.20 or more according to the present invention, the feeling of weight, racket swing-out property, surface stability, hitting sound, etc. It is getting closer. Although the value of the moment of inertia can be adjusted by attaching a lead weight corresponding to this specific gravity to the racket frame, the results of trial hitting showed that the product of the present invention was superior. Presumably, the weight is distributed over the entire string.

Next, description will be made with reference to the drawings. FIG. 1 (a)-
(F) is an example perspective view showing a partial section of a string that can be used in the present invention. In FIG. 1A, 1 is a monofilament constituting a core portion, 2 is a multifilament constituting a sheath portion, and 3 is an outer resin coating portion. FIG. 1B is different from FIG. 1A in that the portion of the sheath of FIG. 1A has two layers of multifilaments 4 and 5. FIG. 1C differs from FIG. 1A in that the core of FIG. 1A is a thin multifilament 6. FIG. 1D is different from FIG. 1C in that the core of FIG. 1C is a slightly thick multifilament 7. FIG. 1E shows only the multifilament 8 having a thin core. FIG.
(F) consists only of the multifilament 9 having a slightly thick core. In the structure shown as an example above, a fiber having a high specific gravity with a polyamide fiber forms an arbitrary combination string.

A description will be given below using a specific embodiment. The methods for measuring the basis weight and the diameter in the following examples are as follows. (1) Weight per unit: The length of the string was measured exactly 1 m, and the weight was determined by weighing with a precision balance. (2) Diameter: measured five times with a micrometer and averaged.

Example 1 In this example, an example in which the composite component for adjusting the specific gravity is a polyamide / lead composite fiber will be described with reference to FIG.

Nylon 6 monofilament having a diameter of 0.87 mm is used as the core component fiber 11, and nylon / lead conjugate monofilament 14 having a diameter of 0.218 mm is used as the coating component fiber, “Alamine M”, 800D (manufactured by Toray Industries, Inc., specific gravity) 2.36) Fourteen were wound in a helical fashion and simultaneously secured using a nylon-based adhesive. Next, this surface was coated with hot-melt nylon 6 and bonded and integrated. Reference numeral 15 denotes an adhesive layer (resin-coated portion) made of hot-melt nylon 6.

In the above, the nylon / lead conjugate monofilament 14 has a lead component 12 in the core,
It is a conjugate fiber having a core-sheath structure in which a nylon component 13 is present in the sheath. This conjugate fiber is obtained by subjecting nylon and lead to composite spinning and then drawing when melt spinning nylon using a composite die.

The obtained string 10 has a tensile strength of 6
0.0kg, knot strength 30.0kg, elongation 23.8%,
The diameter was 1.336 mm. The basis weight is 2.1208g
/ M and specific gravity D were 1.51 (Table 1-Example 1).

Separately, as a comparative example, 14 nylon 66 monofilaments (weight: 0.0372 g / m) having a diameter of 0.202 mm were produced as coating component fibers under the same conditions as in Example 1. The specific gravity D was 1.11 (Table 1-Comparative Example 2).

The above two types of strings and the natural gut of Reference Example 2 were stretched on a carbon fiber reinforced resin racket having a face area of 110 square inches with a vertical and horizontal length of 60 pounds. This racket was actually hit by a high-level player, and the hitting performance was compared and investigated.

As a result, the product of the present invention was clearly improved in terms of weight, swingability, surface stability and hitting sound as compared with the comparative example. And the evaluation result was extremely similar.

Example 2 In this example, an example in which the composite component for adjusting the specific gravity is a polyamide / lead composite fiber will be described with reference to FIG.

Polyamide / lead composite monofilament 24 having a diameter of 0.218 mm as a coating component fiber, "Amiran M", 800D (manufactured by Toray Industries, Inc., specific gravity 2.356) 7
A string 20 was produced in the same manner as in Example 1 except that a book and seven nylon 6,6 monofilaments 25 having a diameter of 0.202 mm were alternately used and wound in a spiral shape. 21 is a monofilament of nylon 6 having a diameter of 0.87 mm, 22 is a lead component, 23 is a nylon component, and 26 is an adhesive layer (resin coating portion).

The resulting string had a tensile strength of 67.3.
kg, nodal strength 34.7 kg, elongation 25.9%, diameter 1.278 mm. The basis weight is 1.7902 g /
m and specific gravity D were 1.40 (Table 1-Example 2).

As a result of comparing and investigating the hitting performance in the same manner as in Example 1, the evaluation result that the performance was very similar to that of the natural gut of Reference Example 3 was obtained. (Example 3) In this example, an example in which the composite component for adjusting the specific gravity is a fiber of a polymer containing fluorine is shown in FIG.
This will be described with reference to FIG.

Polyvinylidene fluoride fiber monofilament 31 (specific gravity 1.77) having a diameter of 0.623 mm was used as the core component fiber, and total denier 1 was used as the covering fiber.
Three 890 denier (315 filaments) nylon 6 multifilaments 32 are used (945 filaments in total), and the coated fibers 32 are impregnated with a polyurethane acrylate-based ultraviolet curable resin, and the number of twists is 8
It was cured and fixed while being wound around the core component fiber 31 while being twisted at 0 turns / m. Then, the surface was coated with hot melt nylon 6. 3
3 is an adhesive layer made of hot-melt nylon 6 (resin-coated portion)
It is.

The obtained string 30 has a tensile strength of 7
4.5 kg, knot strength 39.1 kg, elongation 18.4%, diameter 1.325 mm. The basis weight is 1.8070 g /
m and specific gravity D were 1.31 (Table 1-Example 3).

Although this string was composed of a composite of a monofilament and a multifilament, it was excellent in transparency and very similar in appearance to natural gut. As a result of comparing and investigating the hitting properties as in Example 1,
The evaluation result that the performance was very similar to the performance of the natural gut of Reference Example 2 was obtained.

Embodiment 4 In this embodiment, an example in which the composite component for adjusting the specific gravity is a fiber of a polymer containing fluorine will be described with reference to FIG.

As the core component fiber, a monofilament of polyvinylidene fluoride fiber having a diameter of 0.623 mm (specific gravity: 1.
77) Using 41, 0.140 mm in diameter as coated fiber
Nylon 6 multifilaments 42 were wound in a helical fashion and simultaneously fixed using a nylon adhesive. Furthermore, the same type of nylon 6 monofilament 43,
Around 0.195mm in diameter, 16 wrapped spirally,
At the same time, it was fixed using a nylon adhesive. Then, the surface was coated with hot melt nylon 6. 44 is an adhesive layer (resin-coated portion) made of hot-melt nylon 6.

The obtained string 40 has a tensile strength of 6
7.8kg, knot strength 33.8kg, elongation 27.8%,
The diameter was 1.316 mm. The basis weight is 1.7434 g
/ M and specific gravity D were 1.28 (Table 1-Example 4).

As a result of comparing and investigating the hitting performance in the same manner as in Example 1, the evaluation result that the performance was very similar to the gut performance of Reference Example 3 was obtained. Table 1 summarizes the results of the above examples. In addition, in Table 1 below, in addition to the results of Examples 1 to 4, commercial products of natural gut of various gauges as reference examples, conventional polyamide synthetic strings as comparative examples, and outside the scope of the present invention. The data of the composite string are listed.

[0053]

[Table 1]

[0054]

As described above, according to the racket string of the present invention, the string includes a polyamide-based synthetic fiber and a fiber having a specific gravity larger than that of the polyamide-based synthetic fiber. The specific gravity D (measured at 25 ° C.) shown in Expression 1) is 1.20 or more and 1.6.
By being within the range of 0 or less, the performance of the natural gut which could not be exceeded by the conventional synthetic string, that is, the delicate racket swingability, surface stability, weight feeling, hitting sound, etc. are improved, and the conventional goodness A string having a well-balanced performance can be obtained in combination with a good stretchability, repulsion, retention of stress relaxation, and the like.

Next, according to the method for producing a synthetic string of the present invention, a polyamide synthetic fiber is used as a core component, and a polyamide synthetic fiber and a fiber having a higher specific gravity than the polyamide synthetic fiber are mixed as a sheath component. Wrap around the core component while applying adhesive, then coat with a resin solution or molten resin, dry or solidify, stretch to adjust elongation, then apply a smoothing agent and string Specific gravity (measured at 25 ° C.) of 1.20 or more.
By setting the range to 60 or less, a string with the above-mentioned specific gravity adjusted can be efficiently and rationally manufactured.

[Brief description of the drawings]

FIGS. 1A to 1F are perspective views of an example showing a partial cross section of a string that can be used in the present invention.

FIG. 2 is a sectional view of a string according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a string according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a string according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a string according to a fourth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 monofilament constituting core 2 multifilament constituting sheath 3 outer resin coating 4,5 multifilament of sheath 6 multifilament thin of core 7 slightly thick multifilament of core 8 thin multifilament of core Filament 9 Multi-filament slightly thicker in core 10, 20, 30, 40 String 11, Monofilament fiber in core of 21, 21 Lead component 13, 23 Nylon component 14, 24 Nylon / lead conjugate monofilament 15, 26, 33, 44 Adhesive layer (resin coated portion) 25 Nylon 6,6 monofilament 31,41 Polyvinylidene fluoride monofilament of core component fiber 32 Nylon 6 multifilament of coated fiber 42,43 Nylon 6 multifilament of coated fiber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification symbol FI // D01F 1/10 D01F 1/10 6/90 301 6/90 301 (58) Investigated field (Int.Cl. ⁶ , DB A63B 51/02 D01F 8/10 D01F 8/12 D01F 8/18 D02G 3/44 D01F 1/10 D01F 6/90 301

Claims (11)

(57) [Claims] 1. A string comprising a polyamide synthetic fiber and a fiber having a specific gravity higher than that of the polyamide synthetic fiber, wherein the string has a specific gravity D (measured at 25 ° C.) represented by the following formula (Equation 1). A composite string having a range of 1.20 to 1.60. (Equation 1) 2. The polyamide-based synthetic fiber is a main component of 50% by weight or more, and the fiber having a specific gravity higher than that of the polyamide-based synthetic fiber is a sub-component of less than 50% by weight.
A composite string according to. 3. The synthetic string according to claim 1, wherein the fiber having a higher specific gravity than the polyamide-based synthetic fiber is made of a material having a specific gravity of 1.50 or more. 4. The synthetic string according to claim 2, wherein the auxiliary component is a conjugate fiber obtained by compounding lead with polyamide fiber or a fiber of a polymer containing fluorine. 5. The conjugate fiber obtained by compounding lead with polyamide fiber is a core-sheath conjugate fiber in which the outer component is polyamide and lead is present inside.
A composite string according to. 6. The synthetic string has a core-sheath structure comprising fibers forming a core and fibers forming a sheath.
A composite string according to. 7. The synthetic string according to claim 5, wherein the core-sheath conjugate fiber composited with lead is present in the sheath of the string. 8. The synthetic string according to claim 5, wherein the fiber of the polymer containing fluorine is present in the core and / or the sheath of the string. 9. The synthetic string according to claim 1, wherein the fibers constituting the synthetic string are braided or twisted. 10. The synthetic string according to claim 1, wherein the fibers constituting the synthetic string are integrated by an adhesive. 11. A polyamide synthetic fiber is used as a core component, and a polyamide synthetic fiber and a fiber having a specific gravity higher than that of the polyamide synthetic fiber are mixed as a sheath component, and an adhesive is applied around the core component. It is wound, then coated with a resin solution or molten resin, dried or solidified, stretched for elongation adjustment, and then coated with a smoothing agent to determine the specific gravity of the string (measured at 25 ° C).
A method for producing a synthetic string, wherein the range is from 20 to 1.60.