Monofilament for fishing nets

Abstract

To provide a monofilament for a fishing net that is composed of a polyamide-based resin, in which a strength required by the fishing net is maintained while maintaining flexibility etc. that is an advantage of the polyamide-based resin, and stretching is hard to be caused when an external force is applied or when the material absorbs water, and dimensional stability is provided.SOLUTION: There is provided a sheath core type composite monofilament, in which the filament is composed of a polyester-based resin at the core and a polyamide-based resin at the sheath, a proportion of the polyamide-based resin in the filament is 70 to 90 vol.%, and a cross-sectional area of a cross section of the composite filament is 7.8×10-3 mm2 to 5.0×10-1 mm2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a monofilament constituting a fishing net.

Background Art

[0002] The performances required for a fishing net include high strength, flexibility, easy dyeability, etc. Monofilaments mainly made of polyamide resin are used. Among polyamide resins, in particular, polyamide 6 resin and polyamide 6 / 66 copolymer resin are used. A fishing net made of polyamide resin is excellent in flexibility, so it does not take up much space on the ship and can be stacked in large quantities.

[0003] On the other hand, fixed fishing nets such as stationary nets have good dimensional stability, and fishing nets made of polyester resin with a large specific gravity are often used so as not to sway even a little in waves. Furthermore, those obtained by improving the polyester resin to increase the specific gravity, or those obtained by combining a fluorine-based monofilament and a polyester monofilament with a large specific gravity are used.

[0004] In the net made of the above-mentioned polyamide resin, due to external forces such as its own weight, water resistance, the weight loaded on the catch, further the external force due to friction with the seabed surface, the tension during hauling, etc., the filaments constituting the net are easily stretched, the mesh opens, and the caught fish may escape. Among them, in the case of a bottom trawl net, in addition to the friction with the seabed, due to the tension during pulling generated therefrom, the net may be stretched more than necessary and lead to a broken net. When hauling, since the fishing net comes into contact with the ship's edge, there is also a risk of the net being broken due to this contact friction.

[0005] In a net made of polyamide resin, there is a problem of improving both flexibility and strength, and a fishing net in which a polyamide form unit containing an aromatic group is included in the polyamide resin has been disclosed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a monofilament for fishing nets which is made of a polyamide resin, maintains the flexibility and other advantages of the polyamide resin, maintains the strength required for fishing nets, and has dimensional stability and is difficult to stretch when an external force is applied or when it absorbs water.

[0008] The present inventors focused on the phenomenon that the dimensions of a polyamide monofilament change when an external force is applied.

[0009] Polyamide fibers are generally considered to have good abrasion resistance and are suitably used for bag fabrics and the like. A bag fabric is composed of a woven fabric or the like. In this case, the abrasion resistance is evaluated when the surface of the woven fabric rubs against other objects in a planar manner, and is not an evaluation of the abrasion resistance when an external force is applied to the fiber in the fiber axis direction.

[0010] When an external force is applied to a filament made of polyamide in the filament axis direction, it easily stretches under a low load and has a tendency to stretch more easily when it absorbs moisture. When stretching occurs, the stretched portion is more likely to be damaged because the filament diameter becomes smaller. In the use as a fishing net, since the net is strongly pulled rather than the friction on the net surface, it often rubs against other objects while an external force is applied in the filament axis direction constituting the net. Therefore, the present inventors considered whether it is possible to provide a monofilament for fishing nets that can maintain durability when an external force is applied in the filament axis direction and when friction occurs.

Means for Solving the Problems

[0011] Then, the inventors of the present invention conducted studies to achieve the above problems. As a result, by compounding a polyester resin in a specific ratio in the core part of a filament composed of a polyamide resin, it was found that when a load is applied to the filament, the region of the polyester resin in the core part plays a role in suppressing elongation and deformation, and the present invention was thus achieved.

[0012] That is, the present invention is a core-sheath type composite monofilament, wherein the core part of the filament is composed of a polyester resin and the sheath part is composed of a polyamide resin, and in the filament, the proportion of the polyamide resin is 80 ~90% by volume, and the cross-sectional area of the cross-section of the composite filament is 7.8×10 -3 mm 2 ~5.0×10 -1 mm 2 and it is summarized as a monofilament for fishing nets characterized by this.

[0013] Hereinafter, the present invention will be described in detail.

[0014] The monofilament for fishing nets of the present invention is one in which a polyamide resin and a polyester resin are compounded in a core-sheath type, the core part is composed of a polyester resin, and the sheath part is composed of a polyamide resin. In the core-sheath type, the number of core parts may be 1 or a multi-core of about 2 to 5, but 1 is preferred.

[0015] The cross-sectional shape of the monofilament is not particularly limited, such as circular, elliptical, polygonal, etc., but a circular cross-section is preferable from the viewpoint of mechanical properties and versatility. Also, the cross-sectional shape of the core part is not limited to circular and may be a non-circular shape.

[0016] The polyamide-based resin constituting the sheath portion is not particularly limited as long as it has an amide group in the molecule, and examples thereof include nylon 6, nylon 66, nylon 69, nylon 46, nylon 610, nylon 1010, nylon 11, nylon 12, nylon 6T, nylon 9T, polymetaxylylene adipamide, copolymers or blends of these components, etc.

[0017] The polyester-based resin constituting the core portion is not particularly limited as long as it has an ester bond in the molecule. For example, as aromatic polyesters, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, etc. can be mentioned. Also, as aliphatic polyesters, for example, polylactic acid, polybutylene succinate, polycaprolactone, etc. can be mentioned. Further, within the range that does not inhibit the object of the present invention, blends of the above-mentioned polyesters, or blends of the above-mentioned polyester and a polyester copolymerized with other components may be used. Examples of other components that can be copolymerized include, as dicarboxylic acids, isophthalic acid, naphthalene dicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic anhydride, sebacic acid, adipic acid, succinic acid, etc., and as diol components, ethanediol, propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol, etc. Also, a polyester-based thermoplastic elastomer or a polyester-based thermoplastic elastomer composition may be added to the above-mentioned polyester. The addition amount is at most 10% by mass in the core portion, and preferably 2 - 8% by mass. By including a polyester-based thermoplastic elastomer or a polyester-based thermoplastic elastomer composition in the polyester of the core portion, the bonding property at the interface between the sheath portion made of a polyamide-based resin and the core portion made of a polyester-based resin becomes good, and it becomes difficult to elongate when an external force is applied in the fiber axis direction, which is preferable.

[0018] As the relative viscosity of the polyester resin, in order to have the intended mechanical properties, the relative viscosity is preferably 1.4 or more, more preferably 1.5 or more. Note that when the relative viscosity is high, the mechanical properties tend to be high, but considering handleability and the like, the upper limit of the relative viscosity is preferably about 1.65. The relative viscosity of the polyester was measured at 20 °C using an Ubbelohde viscometer with an isomass mixture solution of phenol / tetrachloroethane at a concentration of 0.5% as the solvent.

[0019] Also, within the range that can achieve the object of the present invention, various additives may be contained in the polyamide resin or polyester resin constituting the monofilament as necessary. For example, crystal nucleating agents, matting agents, pigments, light fastness agents, weather resistance agents, antioxidants, antibacterial agents, fragrances, heat stabilizers, plasticizers, dyes, surfactants, surface modifiers, various inorganic electrolytes and organic electrolytes, fine powders, flame retardants, compatibilizers, and other additives can be mentioned.

[0020] The monofilament for fishing nets of the present invention is mainly composed of a polyamide-based resin, and is characterized in that a polyester-based resin is arranged in the core part of the monofilament composed of the polyamide-based resin. Since the monofilament is mainly composed of a polyamide-based resin, for example, compared with a monofilament composed only of a polyester-based resin, it is excellent in flexibility and has good dyeability. And, by continuously arranging the polyester-based resin in the core part of the monofilament mainly composed of such a polyamide-based resin in the filament axis direction, when an external force is applied to the monofilament or when the polyamide-based resin is added with its own weight due to moisture absorption or water absorption due to the characteristics of the resin, the polyester-based resin is excellent in dimensional stability, so it maintains its form in the axial direction of the monofilament and suppresses deformation due to the elongation of the monofilament itself. And, since deformation due to elongation is less likely to occur, thinning (deformation) in the filament axis direction is suppressed, and damage due to abrasion is less likely to occur. On the other hand, for a monofilament composed only of a polyamide-based resin, it is likely to deform in the axial direction when an external force is applied, the deformed part thins, stress due to abrasion or the like concentrates on the thinned part, and damage progresses more rapidly and easily breaks.

[0021] In the present invention, in order to exhibit the above-described operational effects, the proportion of the polyamide-based resin in the monofilament is 80 ~90% by volume. In the monofilament, when the proportion of the polyamide-based resin is 80 % by volume or more, it is excellent in flexibility, has good dyeability, and sufficiently exhibits practical strength as a fishing net. On the other hand, by setting the proportion of the polyamide-based resin to 90% by volume or less, the dimensional stability and abrasion resistance due to the polyester-based resin are dramatically improved. 。

[0022] The cross-sectional area of the cross-section when the monofilament for fishing nets of the present invention is cut at a right angle to the filament axis direction is 7.8×10 -3 mm 2 ~5.0×10 -1mm 2 is. By setting the cross-sectional area to 7.8×10 -3 mm 2 or more, it is difficult for fluff to be generated due to friction caused by contact with the seabed, ship's edge, etc. On the other hand, by setting the cross-sectional area to 5.0×10 -1 mm 2 or less, the strength per single filament can be effectively exhibited, and the flexibility of the yarn can be maintained, so the workability during net knitting is good. Here, the cross-sectional area is calculated by taking a photo using a microscoop and calculating the area from the photo.

[0023] The monofilament for fishing nets of the present invention can be obtained by the following method. First, using a core-sheath type composite nozzle, a polyamide-based resin is arranged in the sheath part, a polyester-based resin is arranged in the core part, and the ratio of the polyamide-based resin is 80 ~90% by volume, and it is melt-spun after being measured. Next, the yarn obtained by melt-spinning is cooled in a water bath, and after being wound up as an undrawn yarn once or continuously without winding up once, stretching is performed. The draw ratio during stretching is set to 4 to 8 times, and heat stretching is performed. As the heating means for heat stretching, heat stretching is performed in a warm water bath or heat stretching is performed using heating rollers. After heat stretching, a winding operation is continuously performed to obtain the target monofilament.

[0024] Using the obtained monofilament, a fishing net may be obtained by adopting a desired structure with a net knitting machine. When applying it to a net knitting machine, it may be used in the form of a monofilament yarn composed of one strand, or it may be used in the form of a bundle of a plurality of monofilaments.

[0025] Since the monofilament for fishing nets of the present invention is excellent in dimensional stability and abrasion resistance, it can be particularly effectively applied as a non-fixed fishing net such as a bottom trawl net or a gillnet.

Effects of the Invention

[0026] The monofilament for fishing nets of the present invention is excellent in flexibility, has good dyeability, fully exhibits the practical strength as a fishing net, and has a dramatic improvement in dimensional stability and abrasion resistance, and can provide a fishing net excellent in dimensional stability and abrasion resistance.

Brief Description of the Drawings

[0027]

Figure 1

Examples

[0028] Next, the present invention will be described based on examples. Note that the present invention is not limited to the following examples. Also, the measurement methods for characteristic values and the like in the examples are as follows. (1) Tensile strength (N) and elongation (%) Since the monofilament is usually wound up, the required amount unwound is allowed to stand at room temperature for 24 hours or more, and the maximum strength and breaking elongation are measured with a constant speed elongation type tensile tester. The conditions of the tensile test were that the tensile speed was 300 mm / min, the grip interval was 250 mm, and the average value measured at n = 5 was taken as the tensile strength (N) and elongation (%).

[0029] (2) Knot strength In accordance with JIS L 1013, the strength at the time of cutting was measured using a constant speed elongation type tensile tester. Also, the knots were made for both a) and b) tying methods described in JIS L 1013. The tensile speed was 300 mm / min, the grip interval was 250 mm, and the values measured for a) and b) tying methods at n = 5 each were averaged and taken as the knot strength (N).

[0030] (3) Abrasion resistance (flexural wear test) As the wear body, a sandpaper #1500 was attached to the side surface of a metal round bar with a diameter of 20 mm. With respect to this wear body, a sample (monofilament) was brought into contact at an angle of 90 degrees, a predetermined load was applied to one end of the sample, and reciprocating friction was performed at a stroke width of 120 mm and a stroke speed of 35 times / minute until the sample broke, and the number of reciprocations until the sample broke was measured. The sample was measured with n = 3, and the average value of the obtained number of times was taken as the wear number of abrasion resistance. The predetermined load was 3.0 kg per cross-sectional area (mm 2 ). For example, when the cross-section was circular and the wire diameter was 0.2 mm, a load of 94 g was applied. Regarding the evaluation of wet wear, a wear test was conducted using a sample immersed in normal-temperature water for 24 hours or more as the sample. After the start of the wear test, water was not applied to the sample.

[0031] In addition, Fig. 1 shows a schematic perspective view of a bending-type wear test for measuring abrasion resistance.

[0032] Example 1 As the polyamide-based resin disposed in the sheath portion, a blend of 90% by mass of polyamide 6 resin (manufactured by Unitika Ltd., trade name A1030BRF) and 10% by mass of nylon 6·66 copolymer resin (manufactured by DSM, trade name "Novamid 2030J") was prepared. As the polyester-based resin disposed in the core portion, polyethylene terephthalate resin (manufactured by Unitika, trade name "NEH2070") with a relative viscosity ηrel = 1.55 was prepared.

[0033] It was weighed so that the polyamide-based resin (sheath portion) / polyester-based resin (core portion) = 80 / 20 (volume ratio), and melt-spun from a spinneret with a diameter of 2.0 mmφ×9H at a polymer temperature of 280°C under the condition of a spinning speed of 16 m / min (the number of core portions was 1). The melt-spun yarn was cooled in a water bath at 30°C at a speed of 16 m / min, then stretched 3.5 times in a warm bath at 95°C without winding (first-stage stretching), then stretched 1.4 times in a dry-heat atmosphere at 175°C without winding (second-stage stretching), and then relaxed and wound up (total stretching ratio 4.9 times). The obtained core-sheath composite monofilament had a yarn diameter of 0.462 mm and a cross-sectional area of 1.68×10-1 mm 2 (Fineness 1997 dtex), tensile strength 5.3 cN / dtex, elongation 22.0%, and knot strength 3.1 cN / dtex. The evaluation results of abrasion resistance are shown in Table 1.

[0034] Comparative Example 1 As a polyamide resin, a blend of 90% by mass of polyamide 6 resin (manufactured by Unitika Ltd., trade name A1030BRF) and 10% by mass of nylon 6·66 copolymer resin (manufactured by DSM, trade name "Novamid 2030J") was prepared.

[0035] Then, at a polymer temperature of 245 °C, the above blended polyamide resin was melt-spun from a spinneret with a diameter of 2.5 mmφ × 24 holes under the condition of a spinning speed of 26 m / min. The melt-spun yarn was cooled in a water bath at 10 °C at a speed of 26 m / min, and then, without winding, it was drawn 3.4 times in a warm bath at 90 °C (first-stage drawing), and then, without winding, it was drawn 1.4 times in a dry-heat atmosphere at 165 °C (second-stage drawing), and then, after relaxation, it was wound up (total draw ratio 4.6 times). The monofilament consisting only of the obtained polyamide had a yarn diameter of 0.459 mm and a cross-sectional area of 1.65×10 -1 mm 2 (Fineness 1717 dtex), tensile strength 6.1 cN / dtex, elongation 19.2%, and knot strength 3.9 cN / dtex. The evaluation results of abrasion resistance are shown in Table 1.

[0036] Reference Example 2 As the polyamide resin disposed in the sheath portion, a blend of 75% by mass of nylon 6·66 copolymer resin (manufactured by DSM, trade name "Novamid 2330J") and 25% by mass of nylon 6·66 copolymer resin (manufactured by DSM, trade name "Novamid 2030J") was prepared. As the polyester resin disposed in the core portion, polyethylene terephthalate resin (manufactured by Unitika, trade name "NEH2070") with a relative viscosity ηrel = 1.55 was prepared.

[0037] The polyamide resin (sheath part) / polyester resin (core part) was weighed so that the ratio was 70 / 30 (volume ratio), and melt spinning was performed from a spinneret with a diameter of 1.8 mmφ and a length of 6H at a polymer temperature of 270 °C under the condition of a spinning speed of 17.4 m / min (the number of cores was 1). The melt-spun yarn was cooled in a water bath at 10 °C at a speed of 17.4 m / min, then stretched 3.8 times in a warm bath at 85 °C without winding (first-stage stretching), and then stretched 1.53 times in a dry-heat atmosphere at 180 °C without winding (second-stage stretching), and then relaxed and wound up (total stretching ratio 5.8 times). The obtained core-sheath composite monofilament had a yarn diameter of 0.203 mm, a cross-sectional area of 3.23×10 -2 mm 2 , a tensile strength of 6.8 cN / dtex, an elongation of 13.8%, and a knot strength of 4.2 cN / dtex. In addition, Reference In Example 2, the tensile strength, elongation, and knot strength were measured for a state where 6 monofilaments were aligned (fineness 2600 dtex / 6f). The evaluation results of abrasion resistance are shown in Table 1.

[0038] Reference Example 3 As the resin disposed in the core part, except that 95% by mass of polyethylene terephthalate resin (manufactured by Unitika, trade name "NEH2070") with a relative viscosity ηrel = 1.55 and 5% by mass of a polyester-based thermoplastic elastomer composition (manufactured by Mitsubishi Chemical Corporation, trade name "Modic GQ331") were blended, Reference A core-sheath composite monofilament was obtained in the same manner as in Example 2. The obtained core-sheath composite monofilament had a yarn diameter of 0.198 mm, a cross-sectional area of 3.07×10 -2 mm 2 , a tensile strength of 7.4 cN / dtex, an elongation of 14.0%, and a knot strength of 4.4 cN / dtex. In addition, Reference In Example 3, the tensile strength, elongation, and knot strength were measured for a state where 6 monofilaments were aligned (fineness 2339 dtex / 6f). The evaluation results of abrasion resistance are shown in Table 1.

[0039] Comparative Example 2 As the polyamide resin, a blend of 75% by mass of nylon 6 / 66 copolymer resin (manufactured by DSM, trade name "Novamid 2330J") and 25% by mass of nylon 6 / 66 copolymer resin (manufactured by DSM, trade name "Novamid 2030J") was prepared.

[0040] Then, at a polymer temperature of 255 °C, melt spinning was carried out from a spinneret with a diameter of 0.8 mm φ × 54 holes under the condition of a spinning speed of 25 m / min. The melt-spun yarn was cooled in a water bath at 12 °C at a speed of 25 m / min, and then, without winding up, it was drawn 3.5 times in a warm bath at 95 °C (first-stage drawing), and then, without winding up, it was drawn 1.7 times in a dry-heat atmosphere at 215 °C (second-stage drawing). After that, it was relaxed and then wound up (total draw ratio 6.0 times). The obtained fiber had a yarn diameter of 0.200 mm, a cross-sectional area of 3.14×10 -2 mm 2 ², a tensile strength of 8.6 cN / dtex, an elongation of 20.9%, and a knot strength of 4.7 cN / dtex. In Comparative Example 2, the tensile strength, elongation, and knot strength were measured in a state where 6 monofilaments were aligned (fineness 2355 dtex / 6f). The evaluation results of abrasion resistance are shown in Table 1.

[0041]

Table 1

[0042] Example of 1 The monofilament had mechanical properties that were practically sufficient for a fishing net monofilament. Furthermore, as is clear from Table 1, since the dimensional stability was improved, it exhibited abrasion resistance that was dramatically superior compared to Comparative Examples 1 and 2.

Claims

1. It is a core-sheath type composite monofilament, in which the core is made of a polyester resin and the sheath is made of a polyamide resin. In the filament, the proportion of the polyamide resin is 80 to 90% by volume, and the cross-sectional area of the composite filament is 7.8×10 －３ mm ２ ~5.0×10 －１ mm ２ A monofilament for fishing nets, characterized by being such.

2. The monofilament for fishing nets according to Claim 1, wherein the fishing net is a bottom trawl net or a gillnet.

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