JP2023148093A - Core-sheath type conjugate monofilament and method for manufacturing the same - Google Patents

Abstract

To provide a conjugate filament having a loop strength suitable for use as a core yarn for a tennis racket string.SOLUTION: The conjugate filament is a core-sheath type conjugate monofilament formed of a core component made of polyvinylidene fluoride-based resin and a sheath component made of polyamide-based resin. A cross-section of the entire core-sheath type conjugate monofilament is a circular shape, and the cross-section of the core component is a multi-lobe shape. The multi-lobe shape has a plurality of lobe portions 1 protruding outward and a center portion 2 on the inside of the lobe portion 1. A method for manufacturing the core-sheath type conjugate monofilament is as follows. The polyvinylidene fluoride-based resin and the polyamide-based resin are subjected to conjugate melt-spinning to obtain a core-sheath type conjugate undrawn filament having the core component made of the polyvinylidene fluoride-based resin of a multi-lobe cross-section type and the sheath component made of the polyamide-based resin. Then, the core-sheath type conjugate undrawn filament is drawn under heating conditions in multiple steps.SELECTED DRAWING: Figure 1

Description

The present invention relates to a core-sheath composite monofilament whose core component is a polyvinylidene fluoride resin and whose sheath component is a polyamide resin, and to a method for manufacturing the same, and in particular to a core-sheath type composite monofilament that is suitable for use as a core yarn for strings of tennis rackets. The present invention relates to a composite monofilament and a method for manufacturing the same.

BACKGROUND ART Conventionally, island-in-the-sea type composite monofilaments and core-sheath type composite monofilaments have been known as composite monofilaments made of polyvinylidene fluoride resin and polyolefin resin (Patent Document 1). The reason why the polyvinylidene fluoride resin and the polyolefin resin are combined is to make the specific gravity suitable for a fishing line, that is, to make the specific gravity lower than that of the polyvinylidene fluoride resin and higher than that of the polyolefin resin. Patent Document 1 describes a sea-island type composite monofilament in which a polyvinylidene fluoride resin is used as a sea component and a polyolefin resin is used as an island component. Further, in the case of a core-sheath type composite monofilament, one is described in which a polyvinylidene fluoride resin is used as a sheath component and a polyolefin resin is used as a core component. Further, a core-sheath type composite monofilament is known as a composite monofilament made of a polyvinylidene fluoride resin and a polyamide resin (Patent Document 2). Patent Document 2 states that the polyvinylidene fluoride resin may be a core component or a sheath component. This is also to make the specific gravity suitable for a fishing line, as in the case of Patent Document 1, that is, to make the specific gravity lower than that of polyvinylidene fluoride resin and higher than that of polyamide resin.

Both of the composite monofilaments described in Patent Documents 1 and 2 are for use in marine materials such as fishing lines and fishing net lines. The present inventor had been developing a core thread for tennis racket strings, but although the composite filaments described in Patent Documents 1 and 2 have specific gravity and tensile strength suitable for fishing lines, they cannot be used for tennis racket strings. It was not suitable as a core yarn. Since the strings of a tennis racket are tensioned by being hooked to the frame, the string core yarn is required to have high hooking strength.

Japanese Patent Application Publication No. 2003-64530 JP 2021-70898 Publication

An object of the present invention is to obtain a composite filament having a hooking strength suitable for use as a core yarn for strings of tennis rackets.

In order to solve the above problems, the present inventor investigated the reason why the hooking strength of a core-sheath type composite monofilament whose core component is a polyvinylidene fluoride resin and whose sheath component is a polyamide resin is low. As a result, it was found that this is because the adhesion between the polyvinylidene fluoride resin and the polyamide resin is low, and the sheath component peels off from the core component at the hook portion.

The present invention was made based on the above findings, and solves the above problems by improving the adhesion between the core component and the sheath component. That is, the present invention provides a core-sheath type composite monofilament in which the core component is a polyvinylidene fluoride resin and the sheath component is a polyamide resin, and the cross-sectional shape of the entire core-sheath type composite monofilament is circular; The present invention relates to a core-sheath type composite monofilament whose components have a multilobal cross-sectional shape, and a method for producing the same.

In the core-sheath type composite monofilament according to the present invention, a polyvinylidene fluoride resin is used as a core component, and a polyamide resin is used as a sheath component. As the polyvinylidene fluoride resin, a vinylidene fluoride homopolymer (polyvinylidene fluoride) or a vinylidene fluoride copolymer of vinylidene fluoride and other monomers is used. Any other monomer can be used as long as it copolymerizes with vinylidene fluoride. For example, tetrafluoroethylene, monochlorotrifluoroethylene, vinyl fluoride, hexafluoroprepylene, or perfluoroisopropoxyethylene may be used alone. Alternatively, they can be used in combination. The core component may be a mixture of a plurality of polyvinylidene fluoride resins, or may be a polyvinylidene fluoride resin mixed with a small amount of another resin. Further, a heat stabilizer, a coloring agent, an antioxidant, a plasticizer, etc. may be added to the polyvinylidene fluoride resin alone or in combination.

In the present invention, the core component has a multilobed cross-sectional shape. The multi-lobed type refers to one having a plurality of outwardly protruding parts (leaf parts 1), as shown in FIGS. 1 to 3. 1 to 3 have six leaf portions 1, so they are six-lobed. A central portion 2 exists inside the leaf portion 1. In the present invention, it is preferable to have three to eight leaf portions 1, that is, a three-lobed to eight-lobed shape. If the shape is less than three-lobed, the protruding portion will be too small and the adhesion with the sheath component will not improve. Moreover, if the shape exceeds the eight-lobed shape, the cross section tends to approximate a circle, and the adhesion with the sheath component tends not to improve.

The polyamide resin that is the sheath component surrounds the polyvinylidene fluoride resin that is the core component. The polyamide resin is not particularly limited as long as it has an amide group in its molecule, and examples include nylon 6, nylon 66, nylon 69, nylon 46, nylon 610, nylon 1010, nylon 11, nylon 12, Nylon 6T, nylon 9T, polymethaxylene adipamide, etc. are used. Moreover, a mixture of a plurality of polyamide resins may be used, or a small amount of other resin may be mixed with the polyamide resin. Further, a heat stabilizer, a colorant, an antioxidant, a plasticizer, etc. may be added to the polyamide resin alone or in combination.

Since the core component is made of polyvinylidene fluoride resin, its specific gravity is approximately 1.7 or more. In addition, when it is made only of polyvinylidene fluoride, its specific gravity is approximately 1.78. Since the sheath component is made of polyamide resin, its specific gravity is generally within the range of 1.01 to 1.15. Therefore, the specific gravity of the core-sheath type composite monofilament can be adjusted as appropriate by adjusting the volume ratio of the core component and the sheath component. In the core-sheath type composite monofilament according to the present invention, the volume ratio of the core component is preferably 10 to 35% by volume, and in this case, the specific gravity of the core-sheath type composite monofilament is approximately within the range of 1.20 to 1.35. It can be adjusted with If the volume ratio of the core component is less than 10% by volume, the specific gravity or rigidity of the core-sheath type composite monofilament will not increase, and when used as a core thread for strings of tennis rackets, it will tend to be difficult to obtain a powerful shot feel. . If the volume ratio of the core component exceeds 35% by volume, the flexibility of the core-sheath type composite monofilament will decrease when used as a core thread for tennis racket strings, and the impact when hitting a tennis ball will tend to be stronger. .

The overall cross-sectional shape of the core-sheath type composite monofilament according to the present invention is circular. That is, the sheath component surrounds the core component having a multilobal cross-sectional shape, resulting in a core-sheath type composite monofilament having a circular cross-sectional shape. The wire diameter of the core-sheath type composite monofilament is arbitrary. When used as a core yarn for monostrings of tennis rackets, the diameter is preferably 0.8 to 1.0 mm, in accordance with the general wire diameter of monostrings (approximately 1.33 to 1.41 mm). Furthermore, when using the core thread for multi-strings of tennis rackets, it is preferable to use a multifilament thread made by bundling a plurality of monofilaments with a wire diameter of 1 to 7 μm. Furthermore, when used as a fishing line (including fishing line and fishing line), it is preferably 0.1 to 1.0 mm.

The core-sheath type composite monofilament according to the present invention is produced by composite melt spinning using a polyvinylidene fluoride resin and a polyamide resin, and the core component is a polyvinylidene fluoride resin whose cross section is multilobed, and the sheath component is a polyvinylidene fluoride resin whose cross section is multilobed. It can be produced by obtaining a core-sheath type composite undrawn filament made of a polyamide resin and then drawing the undrawn filament under heating. Composite melt spinning is performed by spinning a core component through a spinning hole having a shape similar to that shown in FIGS. 1 to 3, and then spinning a sheath component around the core component. Alternatively, the core component may be spun and combined from a plurality of adjacent circular holes, and the sheath component may be spun from around the core component. By such composite melt spinning, a core-sheath type composite undrawn filament having a core component having a multilobal cross section can be obtained.

The core-sheath type composite undrawn filament is cooled if desired and then drawn under heating. Heating may be performed in a moist heat atmosphere such as in hot water or hot oil, or may be performed in a dry heat atmosphere such as in the air or gas. Furthermore, the stretching may be performed in one step or in multiple steps. For example, the stretching may be performed in a wet heat atmosphere in the first stage, and the stretching may be performed in a dry heat atmosphere in the second stage. In the present invention, since the core component is multi-lobed, it has the advantage that heat can be easily transmitted to the central portion 2 of the core component and the core component can be easily stretched, compared to a core component with a circular cross section. be. Although the stretching ratio is arbitrary, it is preferable that the total stretching ratio is 2 to 8 times. When the total stretching ratio is high, it is preferable to carry out the stretching under heating in multiple stages in order to obtain uniform yarn quality.

In order to manufacture tennis racket strings using the core-sheath type composite monofilament according to the present invention, the core-sheath type composite monofilament is used as a core yarn, the surface of which is covered with a thin multifilament yarn or a thin monofilament yarn, and a polyurethane resin is used. It can be hardened with resin such as Moreover, the core-sheath type composite monofilament according to the present invention can be used as it is as a fishing line. The core-sheath type composite monofilament according to the present invention can be used not only as a core thread for a tennis racket string or a fishing line, but also as a marine material such as a thread for a fishing net, or for other conventionally known uses.

In the core-sheath type composite monofilament according to the present invention, the core component is made of polyvinylidene fluoride resin, the sheath component is made of polyamide resin, and the cross-sectional shape of the core component is multilobal. This has the effect of improving the adhesion of the sheath component and improving the hooking strength. Therefore, when used as the core yarn of a string for a tennis racket, the strength of the hooking portion to the frame of the racket is improved and the string is difficult to break. Furthermore, when used on a fishing line, the strength of the hook-and-knot part with the fishhook is improved, making it difficult for the fishing line to break.

In addition, since the core component has a multi-lobed cross section, heat is easily transmitted to the center of the core component during the drawing process under heating during the production of core-sheath type composite monofilament, and the drawing conditions for polyamide fibers are This has the effect that polyvinylidene fluoride resin can also be stretched well.

Example 1
As the polyvinylidene fluoride resin, polyvinylidene fluoride resin (product name "6010/0000" manufactured by Sumitomo 3M) was prepared. In addition, a polyamide 6/polyamide 66 copolymer resin (manufactured by DSM, trade name "Novamid 2330J") was prepared as a polyamide resin. Then, the polyvinylidene fluoride resin is melt-spun through seven circular spinning holes 3 with a diameter of 1.0 mm arranged closely as shown in FIG. was melt-spun to obtain a core-sheath type composite undrawn filament. The cross-sectional shape of this core-sheath type composite undrawn filament was circular, and the cross-sectional shape of the core component was six-lobed. In the composite melt spinning, the volume ratio of polyvinylidene fluoride resin to polyamide resin was 15:85, and the melting temperature was 265°C.

The core-sheath type composite undrawn filament was immersed in a 25° C. water bath to cool it, and then immersed in a 90° C. hot bath to perform the first step of drawing in a moist heat atmosphere. Next, a second stage of stretching was performed in a dry heat atmosphere at 260°C, followed by a third stage of stretching in a dry heat atmosphere at 270°C, with a total stretching ratio of 4.5 times. A core-sheath type composite monofilament was obtained. The cross-sectional shape of this core-sheath type composite monofilament was circular, and the cross-sectional shape of the core component was six-lobed.

Example 2
A core-sheath composite monofilament was obtained in the same manner as in Example 1, except that the volume ratio of polyvinylidene fluoride resin to polyamide resin was 20:80. The cross-sectional shape of this core-sheath type composite monofilament was circular, and the cross-sectional shape of the core component was six-lobed.

Comparative example The spinning hole of the polyvinylidene fluoride resin was made into a single circle with a diameter of 2.5 mm, and the volume ratio of the polyvinylidene fluoride resin and the polyamide resin was set to polyvinylidene fluoride resin: polyamide resin = 20:80. Other than that, the composite was melt-spun in the same manner as in Example 1 to obtain a core-sheath type composite undrawn filament. The cross-sectional shape of this core-sheath type composite undrawn filament was circular, and the cross-sectional shape of the core component was also circular and concentric.

This core-sheath type composite undrawn filament was immersed in a 25° C. water bath to cool it, and then immersed in a 90° C. hot bath to perform the first step of drawing in a moist heat atmosphere. Next, a second stage of stretching was performed in a dry heat atmosphere at 260° C., and a total stretching ratio of 5.0 times was performed to obtain a core-sheath type composite monofilament. The cross-sectional shape of this core-sheath type composite monofilament was circular, and the cross-sectional shape of the core component was also circular and concentric.

The wire diameter, specific gravity, and hooking strength of the core-sheath type composite monofilaments obtained in Examples and Comparative Examples were measured by the following methods. The measurement results are shown in Table 1.
(1) Wire diameter (mm)
The wire diameter (mm) was measured using a Digimatic Micrometer MDH-25MB manufactured by Mitutoyo.
(2) Specific gravity The volume of the core-sheath type composite monofilament was calculated based on the wire diameter, the mass of the core-sheath type composite monofilament was measured, and the mass/volume was defined as the specific gravity. Therefore, this specific gravity is synonymous with density.
(3) Hooking strength (N/mm ² )
It was measured by the method described in the section of JIS L 1013 (2021) hooking strength. In addition, if the core-sheath type composite monofilament breaks during the measurement, the strength at this point is taken as the hooking strength, and although the core-sheath type composite monofilament is not cut during the measurement, the sheath component is broken and the core component is exposed. In this case, the strength at this point was defined as the hooking strength.

[Table 1]
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Wire diameter (mm) Specific gravity Hooking strength (N/mm ² )
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Example 1 0.943 1.22 466
Example 2 0.944 1.22 482
Comparative example 0.956 1.27 206
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As is clear from comparing the example and the comparative example, although the wire diameter and specific gravity are almost the same, the core-sheath type composite monofilament of the example has significantly higher hooking strength than that of the comparative example. I can see that it is improving.

FIG. 2 is a schematic diagram showing an example of the cross-sectional shape of the core component of the core-sheath type composite monofilament of the present invention. FIG. 2 is a schematic diagram showing an example of the cross-sectional shape of the core component of the core-sheath type composite monofilament of the present invention. FIG. 2 is a schematic diagram showing an example of the cross-sectional shape of the core component of the core-sheath type composite monofilament of the present invention. 1 is a schematic diagram showing an example of a spinning hole used for melt spinning the core component of Example 1. FIG.

1 Leaf portion of core component 2 Center portion of core component 3 Spinning hole

The overall cross-sectional shape of the core-sheath type composite monofilament according to the present invention is circular. That is, the sheath component surrounds the core component having a multilobal cross-sectional shape, resulting in a core-sheath type composite monofilament having a circular cross-sectional shape. The wire diameter of the core-sheath type composite monofilament is arbitrary. When used as a core yarn for monostrings of tennis rackets, the diameter is preferably 0.8 to 1.0 mm, in accordance with the general wire diameter of monostrings (approximately 1.33 to 1.41 mm). Furthermore, when using the core yarn for multi-strings of tennis rackets, it is preferable to use a multifilament yarn in which a plurality of monofilaments are bundled. Furthermore, when used as a fishing line (including fishing line and fishing line), it is preferably 0.1 to 1.0 mm.

Claims (8)

A core-sheath type composite monofilament in which the core component is a polyvinylidene fluoride resin and the sheath component is a polyamide resin, the entire cross-sectional shape of the core-sheath type composite monofilament is circular, and the cross-sectional shape of the core component is circular. Multi-lobed core-sheath type composite monofilament. The core-sheath type composite monofilament according to claim 1, wherein the multilobed type is a three-lobed to eight-lobed type. The core-sheath type composite monofilament according to claim 1, wherein the volume ratio of the core component is 10 to 35% by volume. A string for a tennis racket using the core-sheath type composite monofilament according to any one of claims 1 to 3 as a core yarn. 5. The tennis racket string according to claim 4, wherein a single core-sheath type composite monofilament is used as the core thread. The tennis racket string according to claim 5, wherein the core-sheath type composite monofilament has a diameter of 0.8 to 1.0 mm. A fishing line made of the core-sheath type composite monofilament according to any one of claims 1 to 3. A core-sheath type composite made by melt-spinning a polyvinylidene fluoride resin and a polyamide resin, the core component of which has a multi-lobed cross section, and the sheath component of the polyamide resin. A method for producing a core-sheath type composite monofilament, which comprises obtaining an undrawn filament and then drawing the undrawn filament under heating.

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