JP7514522B2 - Composite monofilament for fishery materials - Google Patents

Description

The present invention relates to composite monofilaments for marine materials.

Typical fibers used in fishing lines and other marine materials include ultra-high strength polyethylene fibers with a specific gravity of 1.00 or less (approximately 0.92 to 0.94), polyolefin fibers with a specific gravity of approximately 0.91 to 0.96, polyamide fibers with a specific gravity of approximately 1.01 to 1.15, and polyester fibers with a specific gravity of approximately 1.27 to 1.39.

High-strength polyethylene fibers are stronger than ordinary synthetic fibers and are used in a variety of fields, but one drawback is their low specific gravity. With a low specific gravity, they are easily swept away by the wind and float on the water. When used as fishing line, the line between the rod and the water surface becomes loose when the wind blows, and the line floats on the water, making it difficult to tell if there's a bite. When used as a fishing net, the net tends to float due to buoyancy, and the water current causes it to sway a lot. Also, because the single filament is made from extremely thin filaments of 2 dtex or less (1.13 to 1.51 dtex) processed into a multifilament, it has the disadvantage of being poorly resistant to wear and easily frayed.

Polyamide fibers have excellent flexibility, strength, and moderate elongation, so they have a good balance of basic performance as a marine material and are widely used in marine material applications. However, because their specific gravity is only slightly greater than that of water or seawater, they are easily affected by wind and water currents. In addition, polyamide resin itself is water-absorbent, so they absorb water in water and have the disadvantage of poor dimensional stability.

Compared to polyamide, polyester fibers have a higher specific gravity and are less susceptible to the effects of wind and water currents, making use of these characteristics and being used in fixed fishing nets such as set nets. Furthermore, in order to make fixed fishing nets less likely to swing at specific locations, a higher specific gravity is required. For example, Patent Document 1 proposes a mixture of polyvinylidene fluoride fibers and polyester fibers with a specific gravity of 1.5 to 1.75. However, since polyvinylidene fluoride itself has very poor abrasion resistance, in the mixed twisted yarn, the polyvinylidene fluoride fibers cannot withstand external abrasion and are damaged early, posing an issue with the durability of the yarn.

The line with the highest specific gravity is monofilament made of polyvinylidene fluoride (known as fluorocarbon fishing line), which has a specific gravity of over 1.7, the highest among all fishing lines. However, when this fluorocarbon fishing line is abraded by sandpaper or other materials, it is easily scraped off, making it less abrasive.

JP 2013-055910 A

The technical objective of the present invention is to provide a monofilament for use in fisheries that is resistant to being blown away by the wind, does not float in water, is abrasion resistant, and is easy to handle.

The inventors conducted research to achieve the above objective and arrived at the present invention.

That is, the gist of the present invention is a core-sheath type composite monofilament for fishery materials, characterized in that the composite monofilament has a fluororesin in the core and a polyester resin in the sheath, the polyester resin accounts for 40 to 90 volume % of the composite monofilament, and the specific gravity of the composite monofilament is 1.4 to 1.6.

The present invention will be described in detail below.

The monofilament for marine materials of the present invention is a core-sheath type composite monofilament in which a polyester resin and a fluororesin are composited in a core-sheath type, and it is essential that the core is composed of a fluororesin and the sheath is composed of a polyester resin. The number of cores in the core-sheath type may be one or multiple cores of about 2 to 5, but one is preferable. In the present invention, a fluororesin with a high specific gravity is placed in the core, and a hard, slippery polyester resin is placed in the sheath to cover the fluororesin, resulting in a monofilament with a high specific gravity and very strong resistance to abrasion, and excellent durability.

The polyester resin constituting the composite monofilament in the present invention is not particularly limited as long as it has an ester bond in the molecule. For example, aromatic polyesters include polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, etc., and aliphatic polyesters include polylactic acid, polybutylene succinate, polycaprolactone, etc. In addition, as long as the object of the present invention is not hindered, the above-mentioned polyesters may be blended with each other, or the above-mentioned polyesters may be blended with polyesters copolymerized therewith. Other components that can be copolymerized include dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic anhydride, sebacic acid, adipic acid, succinic acid, etc., and diol components such as ethanediol, propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol, etc.

The relative viscosity of polyester resin should be 1.4 or higher, taking into consideration abrasion resistance, strength and elongation, etc.

The fluororesin constituting the core of the composite monofilament in the present invention may be any thermoplastic fluororesin having a specific gravity of 1.7 or more, such as polyvinylidene fluoride, polytetrafluoroethylene, and copolymers of tetrafluoroethylene and perfluoroalkoxyethylene. Of these, polyvinylidene fluoride resins are most preferred.

In the present invention, the polyvinylidene fluoride resin means a polyvinylidene fluoride homopolymer or a polyvinylidene fluoride copolymer mainly composed of vinylidene fluoride. Specific examples of polyvinylidene fluoride copolymers include copolymers mainly composed of vinylidene fluoride and copolymerized with tetrafluoroethylene, monochlorotrifluoroethylene, vinyl fluoride, hexafluoropropylene, perfluoroisopropoxyethylene, etc. In addition, the polyvinylidene fluoride resin disposed in the core or sheath of the composite fiber may be a blend of two or more different polyvinylidene fluoride resins. Furthermore, the polyvinylidene fluoride resin may contain a heat stabilizer, a colorant, an antioxidant, a plasticizer, etc., for the purpose of improving the spinnability, thread quality properties, transparency, etc.

In addition, various additives such as crystal nucleating agents, matting agents, pigments, light resistance agents, weather resistance agents, antioxidants, antibacterial agents, fragrances, heat stabilizers, plasticizers, dyes, surfactants, surface modifiers, various inorganic and organic electrolytes, fine powders, and flame retardants can be added to each of the resins constituting the composite monofilament as necessary, so long as the object of the present invention can be achieved.

The specific gravity of the composite monofilament in the present invention is 1.4 to 1.6. By making the specific gravity of the monofilament 1.4 to 1.6, the polyester resin and fluororesin constituting the monofilament can be composited in a core-sheath form, and the capabilities of both polymers can be maximized. If the specific gravity is less than 1.4, the specific gravity is close to that of polyester fiber, and the object of the present invention cannot be achieved. If the specific gravity exceeds 1.6, the proportion of polyester resin in the monofilament tends to be low, making it difficult to obtain a monofilament for fishery materials having the desired practical strength, which is undesirable.

In the present invention, the proportion of polyester resin in the composite monofilament is 40 to 90% by volume. By making the proportion of polyester resin in the composite monofilament 40% by volume or more, the monofilament exhibits practical strength as a monofilament for marine materials, has excellent abrasion resistance, and is excellent in durability. On the other hand, by making the proportion of polyester resin 90% by volume or less, a monofilament for marine materials that is less likely to be blown away by the wind and does not float in water can be obtained.

The thread diameter of the monofilament for fishery materials of the present invention is preferably about 0.1 mm to 2.0 mm.

The monofilament for fishery materials of the present invention has a high specific gravity as described above and is not easily washed away, so it can be suitably used for fishery materials that require fixing in water. It also has high resistance to friction and can be used for fishery materials that come into contact with uneven seabeds, rock surfaces, and driftwood during use. In the case of fishing nets, it can be suitably used for fixed fishing nets such as fixed nets. It is also suitable for fishing lines. It can be particularly suitable for use as fishing line hooks.

The monofilament for marine products of the present invention can be obtained, for example, by the following method. First, using a core-sheath composite nozzle, a polyester resin is placed in the sheath and a fluororesin is placed in the core, and the polyester resin is weighed out so that the ratio of the polyester resin is 40 to 90% by volume, and melt spun.

The spinning speed during melt spinning is 12 to 30 m/min. If the spinning speed exceeds 30 m/min, the highly viscous fluororesin will not be able to keep up with the plastic deformation at that spinning speed and will not be able to deform uniformly, resulting in uneven thickness and thinness in the stretching direction, which will cause unevenness in the thread diameter and stretching breakage. On the other hand, if the spinning speed is less than 12 m/min, the spinning speed is too slow for the polyester resin, causing stretching unevenness (thickness and thinness) in the polyester resin, which will cause unevenness in the thread diameter and stretching breakage.

When producing monofilaments made of fluororesin, the spinning speed during melt spinning is generally set to a few meters per minute to about 10 meters per minute. This is because fluororesin has a high melt viscosity, and so it is necessary to spin at a low speed to prevent uneven stretching during spinning. However, in the present invention, by setting the spinning speed within the above specific range, it is possible to provide the monofilaments made of a composite of fluororesin and polyester resin with the performance required for use in marine materials.

The melt-spun yarn is then cooled in a bath at 50-70°C, and then the first stage of drawing is performed in a warm water bath at 65-95°C. The melt-spun yarn may be cooled in a water bath at the above-mentioned temperature or in an ethylene glycol bath, but a water bath is preferred because it is easier to handle.

In general, when producing a monofilament made of a fluororesin, cooling after melt spinning is performed in an ethylene glycol bath (approximately 20-80°C), and then the first stage of drawing is performed in a glycerin bath at 150-170°C. However, to obtain the composite monofilament of the present invention, the melt-spun yarn is cooled in a bath at 50-70°C, and then the first stage of drawing is performed in a warm water bath at 65-95°C. If the first stage of drawing is performed in a glycerin bath at 150-170°C, a composite monofilament having practical mechanical strength and knot strength cannot be obtained. This is thought to be because the polyester resin that constitutes the composite monofilament becomes super-drawn in the glycerin bath at 150-170°C, and does not form a good crystal structure. However, if the temperature of glycerin is lowered to about 100°C, the viscosity becomes too high, making it difficult to handle and hindering the manufacturing process, and it is difficult to completely remove the glycerin attached to the yarn surface in the subsequent process, so the filament surface becomes rough in the heat treatment after the second stage drawing, resulting in poor quality. In the present invention, the draw ratio in the first stage drawing is preferably 3.0 to 4.5 times.

The yarn that has been subjected to the first stage drawing is then subjected to a second stage drawing and a relaxation heat treatment at 100 to 250°C to obtain the monofilament for fishery materials of the present invention. The second stage drawing and relaxation heat treatment at 100 to 250°C further orients the crystal structure formed in the polyester resin by the above-mentioned first stage drawing, thereby obtaining a monofilament with practical mechanical strength and knot strength. The draw ratio in the second stage drawing is preferably 1.3 to 2.0 times, and a third stage drawing is further performed as necessary, with a total draw ratio of preferably 5.0 to 7.0 times. The third stage drawing, which is performed as necessary, is preferably more than 1 time and 1.5 times or less.

If the second stage drawing and relaxation heat treatment are performed at 100°C, it is preferable to perform the second stage drawing and relaxation heat treatment in a hot water bath. If the second stage drawing and relaxation heat treatment are performed at a temperature exceeding 100°C, it is preferable to perform the hot drawing in a dry heat atmosphere using a heater. After the hot drawing and relaxation heat treatment, the composite monofilament of the present invention is obtained by winding.

The monofilament for marine products of the present invention is constructed by compounding a core-sheath composite in which a fluororesin forms the core and a polyester resin forms the sheath. Since it has a specific gravity suitable for marine products, it is not easily washed away in water, has excellent abrasion resistance, and is highly durable.

FIG. 2 is a schematic perspective view of a bending type abrasion test for measuring abrasion resistance.

Next, the present invention will be described based on examples. Note that the present invention is not limited to the examples below. The measurement methods for the characteristic values in the examples are as follows.

1. Tensile test After leaving the specimen at rest for 24 hours or more at room temperature, the maximum strength and breaking elongation were measured using a tensile tester. The conditions of the tensile test were a test speed of 300 mm/min, a gripping distance of 250 mm, and the average values measured with n=5 were taken as the maximum strength (N) and breaking elongation (%).

2. Abrasion resistance (flexion type abrasion test)
The wear body was a metal rod with a diameter of 20 mm, with sandpaper #1500 attached to the side. The test sample was brought into contact with the wear body at an angle of 90 degrees, and a predetermined load was applied to one end of the sample, which was rubbed back and forth with a stroke width of 120 mm and a stroke speed of 35 times/min, and the number of reciprocations until the test sample broke was measured. Measurements were performed on n=3 test samples, and the average of the measured values was taken as the number of wears required for wear resistance. The predetermined load was 4.13 kg per cross-sectional area ( ^mm2 ) of the test sample. For example, if the wire diameter was 0.28 mm, a load of 255 g was used.
FIG. 1 is a schematic perspective view of a bending type abrasion test for measuring abrasion resistance.

3. Specific Gravity Approximately 3 g of a sample was prepared, and the density was measured using a true density measuring device BELPycno (manufactured by Microtrac-Bell) to determine the specific gravity.

Example 1
A polyethylene terephthalate resin (manufactured by Unitika, product name "NEH2070", relative viscosity ηrel = 1.55) was prepared as the polyester resin to be disposed in the sheath, and a polyvinylidene fluoride resin (manufactured by 3M, product name "Dyneon PVDF6010/0000") was prepared as the fluorine resin to be disposed in the core.

The polyester resin (sheath)/fluororesin (core) ratio was measured at 80/20 (volume ratio), and melt spun from a 1.5 mmφ×6H spinneret at a polymer temperature of 265° C. and 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 60° C. at a speed of 17.4 m/min, and then stretched 3.4 times in a warm bath at 85° C. without winding (first-stage stretching), then stretched 1.7 times in a dry heat atmosphere at 140° C. without winding (second-stage stretching), and then relaxed and wound up (total stretching ratio 5.8 times). The obtained core-sheath type composite monofilament had a yarn diameter of 0.288 mm, a fineness of 956 dtex, a tensile strength of 768 N/mm ² , an elongation of 18.7%, a knot strength of 484 N/mm ² and a specific gravity of 1.47.

Comparative Example 1
A polyvinylidene fluoride resin (manufactured by 3M, product name "Dyneon PVDF6010/0000") was prepared as the fluororesin, and a polyethylene terephthalate resin (manufactured by Unitika, product name "NEH2070", relative viscosity ηrel = 1.55) was prepared as the polyester resin. The fluororesin was arranged in the sheath, and the polyester resin was arranged in the core.

The resins were weighed so that the volume ratio was 20/80 (fluorine-based resin (sheath)/polyester-based resin (core)), and melt-spun from a 1.5 mmφ×6H spinneret at a polymer temperature of 265° C. and 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 60° C. at a speed of 17.4 m/min, and then stretched 3.4 times in a warm bath at 85° C. without winding (first-stage drawing), then stretched 1.7 times in a dry heat atmosphere at 225° C. without winding (second-stage drawing), and then relaxed and wound up (total draw ratio 5.8 times). The obtained core-sheath type composite monofilament had a yarn diameter of 0.284 mm, a fineness of 959 dtex, a tensile strength of 680 N/ ^mm2 , an elongation of 23.1%, a knot strength of 461 N/ ^mm2 , and a specific gravity of 1.46. The results of the abrasion resistance are shown in Table 1. In the bending abrasion test, the monofilament broke after the first reciprocating abrasion. This was because the sheath part had peeled off at the abraded area, and the composite monofilament could not maintain its shape, so it was determined to have no abrasion resistance.

Comparative Example 2
A monofilament consisting of only polyvinylidene fluoride was produced using only polyvinylidene fluoride resin (manufactured by 3M under the trade name "Dyneon PVDF6012/0000"). That is, melt spinning was performed at a polymer temperature of 250°C from a 1.1 mmφ×6H spinneret at a spinning speed of 5.4 m/min (single-layer filament). The melt-spun yarn was cooled in an ethylene glycol bath at 60°C at a speed of 5.4 m/min, and then drawn 3.3 times in a glycerin bath at 157°C without winding (first-stage drawing), and then drawn 1.4 times in a dry heat atmosphere at 160°C without winding (second-stage drawing), and then drawn 1.28 times in a dry heat atmosphere at 170°C without winding (third-stage drawing), after which it was relaxed and then wound up (total draw ratio 5.9 times). The obtained monofilament had a thread diameter of 0.305 mm, a fineness of 1214 dtex, a tensile strength of 872 N/mm ² , an elongation at break of 24.3%, a knot strength of 563 N/mm ² , and a specific gravity of 1.78. The results of the abrasion resistance are shown in Table 1. The monofilament broke after 94 reciprocal abrasion cycles, and the abrasion resistance was very poor.

Comparative Example 3
As the polyamide-based resin, only nylon 6-66 copolymer resin (manufactured by DSM, product name "Novamid 2030J") was used to produce a monofilament consisting of only polyamide-based resin. That is, melt spinning was performed under the conditions of a polymer temperature of 275°C and a spinning speed of 20 m/min from a 1.5 mmφ x 13H spinneret. The melt-spun yarn was cooled in a water bath at 12°C at a speed of 20 m/min, and then stretched 3.4 times in a warm bath at 95°C without winding (first stage stretching), then stretched 1.6 times in a dry heat atmosphere at 185°C without winding (second stage stretching), and then stretched 1.1 times in a dry heat atmosphere at 190°C without winding (second stage stretching), after which it was relaxed and wound up (total stretching ratio 6.0 times). The obtained composite monofilament had a yarn diameter of 0.290 mm, a fineness of 756 dtex, a tensile strength of 910 N/mm ² , an elongation of 29.9%, a knot strength of 818 N/mm ² and a specific gravity of 1.14.

The core-sheath type composite monofilament of Example 1 of the present invention has a specific gravity suitable for use as a fishery material, and has practical tensile strength and knot strength, as well as extremely excellent abrasion resistance.

Claims (4)

A core-sheath type composite monofilament for use in fishery materials, characterized in that the composite monofilament has a fluororesin core and a polyester resin sheath, the polyester resin accounts for 40-90% by volume of the composite monofilament, and the specific gravity of the composite monofilament is 1.4-1.6. The composite monofilament for fishery materials according to claim 1, characterized in that the fluororesin is a polyvinylidene fluoride resin. A fishing line made from the composite monofilament according to claim 1 or 2. 3. A fishing line comprising the composite monofilament according to claim 1 or 2.