JPS5941365B2 - Aquaculture fish cage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire net used underwater, particularly under the sea, that is, a cage for aquaculture and fishing, and the cage is made of metal wire using polyamide resin as a thermoplastic resin coating. It is characterized by this.

Most of the thermoplastic resin-coated anti-corrosion iron wires that have traditionally been used for wire mesh, etc. have a coating made of soft or medium-hard vinyl chloride resin, and are widely used in general fences, lock nets, etc. However, in recent years, as marine development has been actively promoted in various parts of Japan in accordance with the national situation of Japan, its use has expanded in this field, and the demand for it has increased, for example, for underwater fences and coexistence cages for aquaculture and fishing. It is on the rise.

However, when used under the sea, it is exposed to harsh natural conditions that cannot be encountered during normal land use. Problems with hard vinyl chloride-coated iron wires include abrasion or crushing peeling of the coating due to entanglement or squeezing, destruction of the coating due to collisions with drifting objects, anchors, etc. in the history of ships, etc.

In addition to these film failures that occur after being immersed in the sea, secondary labor after the wire coating process, such as wire netting, selvage processing, or wire mesh processing, There are also many mechanical injuries to the skin.

All of these scratches on the film before and after being immersed in the sea cause seawater to enter the film and lead to corrosion, breaks, and glands in the core wire.

Particularly in aquaculture fisheries, from the viewpoint of contamination of aquaculture fish by zinc in galvanized wire cages that have been used since the beginning, and from the viewpoint of extending the life of the cage itself, cages made of soft or medium-hard vinyl chloride coated iron wire are becoming widespread. However, accidents often occur in which aquaculture fisheries are lost overnight due to wire breakage due to the above-mentioned failures, and there is a strong desire to improve the overall anticorrosion function, focusing on the mechanical strength of the coating.

The inventor of the present invention focused on this point, and as a result of various studies on extrusion anti-corrosion coating of metal wires using crystalline engineering plastics with excellent mechanical properties, we found that homopolyamide resin, for example,
Polyamide 6, polyamide 66, polyamide 610, polyamide 11, polyamide 12, polyamide 612, or multi-component polyamide copolymers using these monomers, such as polyamide 6/12, polyamide 6/66/12, or units having intermediate compatibility with each other. A metal wire such as an iron wire is coated with a polyamide resin such as a mixture of a polymer and a polyamide copolymer, for example, a mixture of polyamide 12 and polyamide 6/12 to a thickness of 100 μm or more.

More preferably, vinyl chloride vinyl acetate copolymer resin,
Using an adhesive or anticorrosion paint based on epoxy resin, polyurethane resin, epoxy phenol resin, or polybutadiene rubber nato as a primer, the polyamide film is firmly adhered to the metal wire.

For example, a primer based on polybutadiene rubber (for example, Patent Application No. 332 of 1975: m'
A primer prepared by mixing a polymer compound obtained by polymerizing a diene compound disclosed in No. 9 with magnesium oxide, or a primer obtained by polymerizing a diene compound disclosed in Patent Application No. 116099 of 1975. From the viewpoint of water resistance, polyamide 12 or polyamide 12 and polyamide 6/12 (both caprolactam and laurin lactam) are baked onto a metal wire coated with a primer made of a mixture of a polymer compound, magnesium oxide, and cobalt ions and/or manganese ions. A mixture of (polymer) is coated with a thickness of 100 μm or more using an extrusion method, and at the same time the film is adhered to the core wire.

The present invention is suitable for use in water, particularly in seawater, and the polyamide resin in this case has a saturated water absorption rate (
The water temperature 20.c) is 5% or less, preferably 3% or less, such as nylon 11 (1.9%), nylon 1
2 (1.5%), nylon 612 (3%), etc.

There are also copolymers and mixtures with homopolymers containing these monomers as main components.

It has been found that the present invention significantly improves many of the drawbacks of the above-mentioned soft vinyl chloride coated anti-corrosion iron wire.

At this time, if the medium wire of the metal wire forming the core wire is galvanized and then coated with the above resin, a more preferable product can be obtained from the viewpoint of corrosion prevention, and the primer used at this time is based on epoxy phenol resin. (For example, a primer consisting of 70 to 80 parts by weight of an epoxy resin, 30 to 20 parts by weight of a novolac type alkylphenol resin, and 1.25 to 2.5 parts by weight of an acid catalyst disclosed in Patent Application No. 121896 of 1975) is good. gives good results.

The cage of the present invention has a diameter of 0.5mm and a diameter of 8M, generally 2mm.
The wire is formed by extruding a polyamide resin coating having a thickness of 0.1 to 1.0 mm onto a metal wire of ~5M iron wire, for example, in the form of a net.

Iron wire is particularly preferred as the core metal wire in the present invention.

Furthermore, the use of a weathering stabilizer or the coloring of the polyamide film black or the like for the purpose of improving the weather resistance of the polyamide film does not pose any problem to the present invention.

The reason why a film made of such a polyamide resin has an outstanding anti-corrosion function is that in addition to the strong mechanical strength and excellent friction and wear properties of the polyamide resin itself, it also has a thickness of about 50 to 100 μm on the outer surface of the film by water cooling during extrusion coating. A skin layer with low crystallinity and high elasticity is formed, and the entire film has a structure in which a buffer zone against external impact is provided on the deep layer of the film, which has high crystallinity and high hardness. Moreover, since the deep layer with high hardness is firmly bonded to the core wire, there is no slippage between the coating and the core wire when an external load is applied, and the coating is extremely safe against peeling. This is because it has become.

Furthermore, it is usually extremely difficult to reliably prevent corrosion within the core wire coating due to minute amounts of water and oxygen that permeate through the coating, even with soft chloride beer coatings or polyamide coatings. In the coating according to the present invention, the single layer of primer that is firmly adhered to the core iron wire acts as an insulator and prevents the ionization of iron, thereby preventing corrosion from progressing within the coating. Even if a scratch occurs, since the coating and the core wire are bonded together, seawater is reliably prevented from penetrating into the interface between the core wire and the coating, which is the reason why the coating further strengthens its anti-corrosion function.

The coated metal wire used in the cage of the present invention is not easily damaged and has excellent resistance to mechanical and chemical attacks.

The polyamide coating firmly adheres to the iron wire, thereby preventing blistering, peeling, cracking, etc. caused by seawater or the like entering between the metal wire and the polyamide coating.

Furthermore, the coating does not easily crack when bent at either low or high temperatures.

Furthermore, the coating can be easily applied by extrusion processing of the through hole.

Furthermore, a particularly noteworthy feature of the polyamide coating of the present invention is that it is much easier to remove marine organisms that adhere to and propagate on the coating after being immersed in the sea, compared to soft or medium-hard vinyl chloride coatings.

This characteristic is extremely important in aquaculture and fisheries.

This is because all the lines in the aquaculture and fishing cages have food attached to them, making them an extremely fertile medium, and the surrounding seawater itself is also rich in nutrients due to feeding and excrement from aquaculture and fishing.

Therefore, the growth of algae or shellfish attached to the wire mesh is abnormally fast, and the wire mesh becomes clogged in a very short period of time, so if left as is, the inside of the cage will become oxygen deficient and the aquaculture fish will die.

As a countermeasure, adding antifouling agents to the film was considered, but this was rarely put to practical use due to concerns about soil contamination and chemical damage to aquaculture and fisheries, which were ineffective.

Therefore, during the breeding season from April to October, fish farmers regularly have divers dive around the cages 2 to 4 times a month to remove organisms that have grown attached to the wire mesh. Furthermore, in the case of soft vinyl chloride coatings, the attachment of these organisms is extremely strong, so it is unavoidable to damage the coating during removal work, reducing the lifespan of the living organisms and increasing costs due to low efficiency. This placed a heavy burden on fish farmers.

On the other hand, polyamide film is similarly powerless against the adhesion and propagation of marine organisms, but it is much easier to remove than soft vinyl chloride film.
At the same time as efficiency is improved, strenuous work that may even damage the coating itself becomes unnecessary, and in combination with the excellent coating strength and anticorrosion ability mentioned above, it can be extremely effective in preserving the cage and prolonging its life.

It is currently unclear what properties of the polyamide film are responsible for the characteristics of such polyamide films against marine life, but polyamide coatings have a much smoother surface than soft or medium-hard vinyl chloride coatings. It is thought that the advantages include that it has excellent resistance to secretions from sea creatures, and that the film surface is stable without deterioration because there are no eluted components such as plasticizers.

As described below, the polyamide resin adhesive coated anti-corrosion steel wire of the present invention significantly improves the anti-corrosion function of the conventional soft vinyl chloride coated anti-corrosion steel wire, and has an excellent effect on extending the life of structures made of steel wire underwater. At the same time, it greatly contributes to reducing conservation costs, and should be used preferentially especially in applications where the propagation of marine organisms is a problem, such as fish cages.

The cage of the present invention is constructed of a polyamide adhesive extrusion coated wire having a cross-sectional structure as shown in FIG.

21 is a metal wire, 22 is a single layer of primer, and 23 is a polyamide layer.

According to the present invention, polyamide coated metal wire is used to create a cage as seen in FIG.

The frame 32 has a float 31 under which a living cage made of metal wire is placed.

Example 1 A soft iron wire (no rust) with a wire diameter of 3.2 m771 was degreased by washing with trichlene and then treated with a polybutadiene primer (manufactured by Daicel Corporation, trade name, F-1-D).
) was applied to a thickness of 10 to 30 μm and baked in an electric furnace at 350° C. for 15 minutes.

Subsequently, while maintaining the iron wire temperature at 200°C, extrusion 1~ of a screw diameter of 40mm equipped with a crosshead die.
Using a machine, the polyamide resin was coated with a wall thickness of 40 m/min at a linear speed of 30 m/min.
It was coated to 0μ and simultaneously cooled continuously in a water cooling bath.

The results of the film strength evaluation test of the polyamide resin adhesive coated iron wire thus obtained are shown in Table 1 together with the film strength evaluation test results of the commercially available medium hard vinyl chloride coated iron wire having the same core wire diameter and film thickness.

Example 2 Table 2 shows the results of a water resistance evaluation test of a polyamide-coated iron wire manufactured in the same manner as in Example 1 and a commercially available medium-hard vinyl chloride-coated iron wire having the same core wire diameter and coating thickness.

Example 3 Polyamide 12 (A-covered iron wire (iron wire double-bare soft iron wire, wire diameter 3.2 rran, coating thickness 400 μm) produced in the same manner as in Example 1 was made into a wire mesh with a mesh size of 60 mm. 10rn
An aquaculture cage with a square shape and a depth of 6 m was created and put to practical use as a soil cage for gusset aquaculture.

In addition, for comparison, an aquaculture cage made of the same type of medium-hard vinyl chloride-coated iron wire was put to practical use as a soil cage for gusset aquaculture.

The ryoikesu was immersed in the sea on March 24th, and one month later on April 24th.
On May 24th and two months later, work was carried out to remove seaweed, shellfish, and other attached organisms that had grown on the wire mesh.

The removal work was carried out by one diver using a bamboo bow.
After removing most of the proboscis, use a spatula to scrape off only the parts with particularly strong adhesion, and when observed in water from a position several meters away from the side of the arranging the proboscis, it is finished when the condition is the same as that immediately after immersion. It was decided that

The time required for this work was 1 hour and 40 minutes for polyamide 12 (A) on April 24th.
41-1, which was coated with medium-hard vinyl chloride, was 2 hours and 30 minutes.

Also, in the case of polyamide 12<A) on May 24th, 2 hours 1
5 minutes, while in the case of the Machinaka rigid vinyl chloride coating, it took 4 hours and 20 minutes.

After the removal work was completed on May 24th, the film surface was observed in detail in A and BE, and the polyamide 12(5) coated cages had sufficient luster on the film, and there was little residual adhesion of shellfish, and almost no scratches on the film were observed. There wasn't.

On the other hand, in the case of medium-hard PVC grade, many local discolorations were observed, and a large amount of residual deposits of shellfish were observed.

My father found many scratches made with a spatula when removing deposits, and in some places the core wire was quite exposed.

[Brief explanation of the drawing]

1, 2, and 3 show a test method for a product according to the method of the present invention, FIG. 4 shows a cross-sectional view of the product, and FIG.
The figure shows a specific example of a cage according to the invention.

Claims (1)

[Scope of Claims] 1. A cage for aquaculture and fishing, characterized in that it is constructed of metal wire coated with polyamide resin. 2. The aquaculture and fishing cage according to claim 1, wherein the polyamide resin has a saturated water absorption rate of 5% or less based on the weight of the polyamide resin at a water temperature of 20°C. 3. The fish and aquaculture cage according to claim 1 or 2, characterized in that a polyamide resin film is formed on the metal wire by extrusion molding. 4. The aquaculture and fishing cage according to claims 1 to 3, characterized in that the polyamide resin film is adhered to the metal wire with a single layer of pillar material interposed therebetween.