JPH06238017A - Strings - Google Patents

Abstract

PURPOSE:To provide strings which have high hardening force, enables further fine gauge and excellent in durability by using a core sheath compound monofilament so as to produce a co69-re yarn and forming a sheath part by resin having elastic modulus lower than that of the core part in strings in each of which a core yarn and side yarns made of synthetic resin monofilament are coated with synthetic resin. CONSTITUTION:In strings in each of which a core yarn and side yarns 3 made of a syntheticresin nomofilament are coated with synthetic resin 4, a core and sheath compound monofilament is used so as to produce a core yarn, and the sheath part 2 is formed by resin having elastic modulus lower than that of the core part 1. The sheath part 2 of the core and sheath compound monofilament is made of polyamide resin having the relative viscosity of 4.5 or more. Thus, rigid and stiff strings can be obtained, so that the gauge of strings can be made further fine. As the gauge is made fine, a player can do sharp racket operation, and it is possible to obtain srings which are excellent in repulsion, hitting feeling and durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a string made of synthetic fiber used for badminton, tennis and the like.

[0002]

2. Description of the Related Art Conventionally, animal fibers such as sheep intestine have been used as strings. However, although strings made of animal fibers are excellent in shot feeling and resilience, they are expensive and inferior in durability. Generally, strings made of synthetic fibers are often used. Strings made of synthetic fibers are fine gauged by taking advantage of the high strength properties of synthetic fibers. Fine gauges reduce air resistance during use, providing sharp strings. For example, the gauge of strings made of animal fiber has a low tensile strength, so it is necessary to make the gauge thicker. However, the strings made of synthetic fibers have a high tensile strength, so that fine gauges have become possible. However, as the racket becomes higher in quality and larger in size, it is desired to provide thinner strings. Japanese Patent Publication No. 28989/1990 proposes to use a high-viscosity resin for the core yarn as a high strength string.

[0003]

In the above method, the linear tensile strength is improved as the viscosity of the resin is increased, but the knot tensile strength tends to be decreased.

It is an object of the present invention to provide a string having excellent durability, which enables a finer gauge by increasing the strength.

[0005]

Means for Solving the Problems The inventors of the present invention have made earnest studies to solve the above-mentioned problems, and as a result, the core yarn constituting the strings is a core-sheath composite yarn made of a high-viscosity resin, and a sheath resin. Found that a string having a high knot tensile strength can be obtained by using a resin having a lower elastic modulus than the core resin, and has arrived at the present invention.

That is, according to the present invention, in a string in which a core yarn made of a synthetic resin monofilament and side yarns are coated with a synthetic resin, the core yarn is made of a core-sheath composite monofilament, and the sheath portion of the core-sheath composite monofilament is a core. The gist is a string characterized by being made of a resin whose elastic modulus is lower than that of the part.

The present invention will be described in detail below. Figure 1
1 is a cross-sectional view of a string showing an example of the present invention, and FIG.
1 shows the core portion (1) of the core-sheath composite yarn, the sheath portion (2) of the core-sheath composite yarn, the side yarn (3), and the coating resin (4). Core-sheath composite yarn composed of relatively thick monofilament A plurality of side yarns (3) are spirally wound around the surface of the core yarn and fixed with an adhesive. Further, the coating resin (4) strengthens and fixes the core yarn and side yarns.

Important characteristics of strings are resilience, shot feeling, and durability. These characteristics are also affected by the performance of the racket and the tension with which the strings are stretched on the racket, but the resilience, feel at impact, and durability are largely dependent on the materials that make up the strings. Generally, synthetic resins become stiffer and tougher as the molecular weight increases,
Hard and brittle. For strings, a rigid and tough material is also effective in improving resilience, shot feeling, and durability. However, as the rigid and tough surface improves, the strength of the nodule decreases remarkably.

When a monofilament made of a high molecular weight resin is made into a core-sheath composite monofilament and a resin having a lower elastic modulus than the resin at the core is used as the resin at the sheath, the knot strength is improved. Knot strength is an important factor indicating the fracture strength of strings. Those with high knot strength can be stretched with a high tension on the racket and have excellent durability. Knot strength is more important than straight strength.

The elastic modulus described in the present invention means a tensile test method for plastics by molding a resin as a single body JIS K-711.
Elasticity modulus measured according to 3. The elastic modulus is a value that is an index showing the hardness of the resin. That is, by providing a flexible resin layer on the surface of a hard resin, the knot strength was dramatically improved.

Polyamide resin is most suitable as a string material. Polyamide resin is easy to bond,
Has excellent wear resistance and moderate elongation.

As a method for lowering the elastic modulus of the polyamide resin, there is copolymerization of different polyamide raw materials. The value of elastic modulus can be selected by changing the rate of copolymerization.

The relative viscosity is an unknown number obtained by measuring the passage time of a solution of synthetic resin dissolved in 98% concentrated sulfuric acid at a rate of 1% at a temperature of 20 ° C. with an Oswald viscometer and dividing by the passage time of a solvent. Is. This value corresponds to the molecular weight of the resin. The higher the relative viscosity, the higher the molecular weight. Up to now, the relative viscosity of the monofilament for strings has been limited to about 4.0 to 4.5, and it has been considered that the knot strength is lowered when a resin having a relative viscosity higher than that is used and there is a problem. As in the present invention, the relative viscosity is 4.5 to 5.5.
By using this polyamide resin in the core of the core-sheath composite monofilament and using a polyamide resin with a lower relative viscosity than that in the sheath, both the knot strength and the knot strength can be reduced to a high level. It became possible.

The core-sheath composite ratio of the core-sheath composite yarn is 80
It is preferably about 90%. As the ratio of the core portion became smaller, the obtained strings tended to have a poor feel at impact.

[0015]

[Operation] In the present invention, the core yarn is a core-sheath composite yarn,
By making the sheath resin softer than the core resin, the knot strength can be increased. Therefore, as the core yarn, a high-molecular weight polyamide resin having a relative viscosity of 4.5 or more can be used, which can further improve the performance of the strings.

[0016]

EXAMPLES Next, the present invention will be specifically described by way of examples. As the synthetic resin, nylon 6 resin having an elastic modulus of 260 kg / mm ² and a viscosity of 5.5, nylon 6 resin having an elastic modulus of 250 kg / mm ² and a viscosity of 4.5, nylon 6 having an elastic modulus of 170 kg / mm ² and a viscosity of 4.5 Six types of monofilaments (No. A to F) shown in Table 1 were produced using a / 66 copolymer resin (the weight ratio of the copolymer was 85:15).

[0017]

[Table 1]

The monofilaments of Table 1 were used to produce the strings listed in Table 2. Monofilament No.
Monofilament N with A, B, C, D and E as core yarns
Twenty-five spirals were wound with o.F as the side thread. The core yarn and side yarns were fixed with an 85% phenol aqueous solution adhesive. Further, the surface of the side yarn was coated with nylon 6 resin.

[0019]

[Table 2]

The strings obtained in the examples were attached to a racket and tested, and as a result, the examples were superior to the comparative examples in resilience, shot feeling and durability. Particularly, the durability was improved by about 30% as compared with the comparative example.

[0021]

According to the present invention, a monofilament made of a high molecular weight polyamide resin having a relative viscosity of 4.5 or more can be used as a core yarn, and a rigid and tough string can be obtained. I was able to make the gauge even thinner. The thin gauge allows the player to operate a sharp racket, and also provides strings with excellent resilience, shot feeling, and durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a string showing an example of the present invention.

[Explanation of symbols]

 1 core part of a core-sheath composite monofilament that becomes a core yarn 2 sheath part of a core-sheath composite monofilament that becomes a core yarn 3 side yarn 4 coating resin

Claims (2)

[Claims] 1. A string comprising a synthetic resin monofilament core yarn and side yarns coated with a synthetic resin, wherein the core yarn comprises a core-sheath composite monofilament, and the sheath portion of the core-sheath composite monofilament is more elastic than the core portion. Strings made of low-resin resin. 2. The string according to claim 1, wherein the sheath portion of the core-sheath composite monofilament is made of a polyamide resin having a relative viscosity of 4.5 or more.