JPS6222137Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to antifouling fixed nets, aquaculture nets, fish pen nets, etc. that prevent the adhesion and propagation of marine organisms. More specifically, the present invention relates to a fishing net knitted with a net yarn made by mixing and twisting a specific fine copper alloy wire and synthetic fiber. Fishing nets such as hemp yarn fishing nets, wire nets, and synthetic fiber nets used in fixed net fishing, fish pens, and fish farms are submerged in the sea for long periods of time, so they are contaminated with marine organisms such as barnacles, sea squirts, green algae, and diatoms. If the fish breed and are left untreated, the mesh becomes clogged, impairing the flow of seawater, and in the case of fish cages and fish farms, there is a significant lack of dissolved oxygen in the seawater, which can sometimes cause the fish to suffocate to death. In addition, fixed nets are subject to resistance from ocean currents due to marine organisms attached to them, and the fixed nets may be washed away by the ocean currents. Therefore, it is necessary to periodically remove marine organisms attached to fishing nets, but such removal work requires a lot of effort, either by diving or by pulling up the nets, so it is necessary to remove marine organisms attached to fishing nets for a long period of time. What is desired is a fishing net that will not attract marine organisms even if it is soaked. In recent years, as a solution to this problem, fishing nets in which the material of the fishing net is impregnated or contained with an organotin antifouling agent have been proposed, but the agent itself is a toxic substance and the antifouling effect cannot be maintained for a long period of time. At present, its use is avoided because it cannot be expected to do so and is also associated with the problem of marine pollution. On the other hand, since copper prevents the adhesion of marine organisms, various antifouling fishing nets have been proposed in which fine copper wires are twisted into the fishing net material. However, copper has the disadvantage that it corrodes extremely quickly in seawater. For example, fishing nets made of thin copper wires with a diameter of 0.10 to 0.25 mm twisted so as to be exposed to the outside exhibit excellent antifouling properties when initially used in seawater;
The wire will corrode and disconnect in about 3 months, and will be completely dissolved and corroded after 6 months, making it impossible to expect any antifouling effect. In addition, if a fishing net is pulled out of the sea with the thin copper wire broken due to corrosion, there is a risk of injuring the fishermen's hands or other skin with the sharp ends of the broken wire.
There is also the problem of a lack of safety as the broken wire gets stuck in the fish body. For this reason, fishing nets that do not expose the copper wires on the surface, and fishing nets that have fine metal wires that are baser than copper and fine copper wires, have been proposed, but in the case of the former, if cotton, etc. adhere to the surface of the fishing net in seawater, it will cause the inner layer to This effect cannot be expected because it inhibits the dissolution of the twisted copper, and the copper reacts with basic substances to produce poorly soluble basic copper. In the latter case, thin metal wires that are more base than copper, such as iron wires, dissolve and corrode first and break, so there is a danger of the broken tip as described above, and the iron wires that do not constitute the local battery are heavily contaminated with marine organisms. There are drawbacks. In order to solve these drawbacks, the present invention was developed after intensive investigation into whether there is a copper alloy that has better corrosion resistance than copper, is suitable for antifouling properties, is flexible, and can be twisted into synthetic fibers and fishing nets. This is the completed version of this invention. The present invention is an antifouling fishing net characterized by being made of synthetic fibers twisted with fine wires of copper-nickel or copper-nickel-iron alloy. The behavior of each material in seawater will be explained below using test examples. Wire rods with a diameter of 1 mm or 2.5 mm and plate materials of 1 dm ² were fixed to a rigid PVC frame with a width of 1 m and a length of 2 m with nylon threads at appropriate intervals, and hung vertically from an aquaculture raft 2.2 m below the sea surface. It was installed for 20 years, and samples were taken periodically during this period to examine the adhesion and corrosion status of marine organisms, in other words, the amount of solubility of various samples in seawater. To measure the amount dissolved, the weight loss of three types of the same sample was measured and the average value was used. The state of adhesion of marine organisms was based on the following criteria. ×: Almost no adhesion. Δ: Slight adhesion, but no practical problem at all. ▲: Adheres to 15-30% of the total surface. ○: A large amount adheres. These results are shown in Tables 1 and 2.

【table】

[Table] From the results in Table 1, materials such as zinc, tin, lead, and iron are not suitable for antifouling fishing nets because they are heavily contaminated with marine organisms. Copper-zinc alloy wire exhibits the same antifouling properties as copper wire against the adhesion of marine organisms, but its corrosion resistance to seawater, that is, the amount of dissolution is greater than that of copper wire, making it unsuitable for long-term immersion. It is assumed that From Table 2, regarding copper-nickel alloy wires, alloy wires with nickel content in the range of 10 to 30% are 3% higher than copper.
It has ~8 times better corrosion resistance and has antifouling properties against marine biofouling. Particularly preferred are alloys containing 30% nickel. Nickel content 10-30
When less than 0.5% iron is added to the alloy, corrosion resistance against seawater is better than when no iron is added. However, alloys with a nickel content of 40% or more attract marine organisms, so these alloy wires are not practical for use in fishing nets twisted with synthetic fibers. Here, in order to create a flexible fishing net by twisting synthetic fibers and copper alloy wires, copper alloys are easy to cast, highly malleable, and can be processed into thin wires, and the diameter of the thin wires is small. 0.15～
A soft material with a tensile strength of 42 Kg/mm ² or less and an elongation of 10% or more is desirable as the mechanical properties of the thin wire. If the tensile strength is 42Kg/mm2 or ^more and the elongation is low, the synthetic fibers and fine alloy wires that make up the fishing net will lack flexibility, so when the fishing net is bent, the fine alloy wires will buckle, causing the fishing net to deteriorate. This is not desirable because it causes problems in handling. Next, embodiments of the present invention will be described. Polypropylene wire with a diameter of 0.20 mm and copper-nickel alloy wire with a nickel content of 10, 20, and 30% with a diameter of 0.18 mm (tensile strengths of 30, 34, and 38 Kg/mm ² , respectively).
30% elongation or more), make a net yarn with the triple twist configuration shown in Table 3 and Figure 1, with the alloy thin wire as the outermost layer of twist, and place it in a hard vinyl chloride frame with a width of 1 m and a length of 2 m. The specimens were fixed with nylon threads so that they were 100 mm in length and width, hung vertically from an aquaculture raft 2.2 meters below the sea surface, and left for one year, and then pulled up to examine the state of adhesion and corrosion of marine organisms. The results of the observation are shown in Table 4.

【table】

【table】

[Table] From Table 4, it is found that when the ratio of the surface area of the copper-nickel alloy wire to the total surface area of the mesh yarn is 3% or less, as seen in present inventions 1 and 2, the stain resistance of the mesh yarn is 3% or less. It can be seen that there is no need to increase it above 40%. From the above results, when using the antifouling fishing net of the present invention, it has significantly higher corrosion resistance than fine copper wire, so even if it is immersed in seawater for a long period of time, marine organisms will not adhere to it, and the wire will not break. For this reason, the circulation of seawater necessary for fish pens and aquaculture farms is smooth, and there is no shortage of dissolved oxygen in the seawater, so aquaculture can be carried out safely. In addition, fixed nets are not damaged by being washed away by ocean currents, and there is no need to periodically remove attached marine organisms as in conventional fishing nets for aquaculture, which is economically advantageous. As described above, the antifouling fishing net of the present invention has a dramatically extended lifespan and has extremely high industrial utility value.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view showing an example of triple twisting of the antifouling fishing net yarn of the present invention, where 1 is a synthetic fiber and 2 is a copper-
A fine wire made of nickel-based alloy is shown.

Claims (1)

[Scope of utility model registration request] Diameter 0.1-0.5 consisting of nickel content 10-30%
A knitting net is made of a mesh yarn made by twisting a mixture of copper-nickel alloy fine wires of mm in diameter and synthetic fibers such that the surface area of the copper-nickel alloy fine wires is 3 to 40% of the total surface of the net yarn. Antifouling fishing net made from