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Current Situation And Development Trend Of Antifouling Paint In Fishing Nets.
Feb 18, 2018

With the improvement of human living standards, the demand for seafood, and after many years of overfishing, a serious shortage of seafood in the oceans, which prompted the rapid development of Marine aquaculture. At present, the aquaculture industry is mainly offshore, and the proportion of aquaculture is increasing year by year. With the development of the industry, new problems arise, and the first one is the anti-pollution problem of fishing nets [1]. Because, biological fouling and corrosion problem of Marine environment is an environment, sailing ship fouling organisms, sailing will obviously increase the surface frictional resistance [2], reduce speed, any increase in fuel consumption, and increase the number of docking repair. The immersion depth of fishing nets and nets is generally 0 ~ 20 m, which is the most vigorous area of sea life, which makes it easier to attach to sea creatures. The main species are algae, rotifers, bryozoans, barnacles, etc. [3]. The application of antifouling coatings is one of the effective methods to solve the problem of Marine pollution. The present situation and development trend of antifouling coatings are introduced.

1. Pollution damage to fishing nets.

When the fishing net is attached to a large number of Marine organisms, the net weight of the fishing net is multiplied several times, and the fishing net is overworked and the service life is shortened greatly. Moreover, defilement of biological activities also has an erosion and destructive effect on fishing nets [4]. Second fouling organisms jams mesh [5], affect the cages inside and outside the water convection, reduce the content of dissolved oxygen and food supply, reduced water quality in the cages at the same time, increase the breeding the parasite infection and many diseases, farm-raised seafood dysplasia or even deaths, seriously affect the production of seafood farming and quality. Finally, removing the defiler increases the input of manpower, time and financial resources, thereby reducing the fishery profits. For Marine aquaculture, the antifouling of fishing nets has become a critical issue.

The present situation of anti-pollution technology of foreign fishing nets.

As early as 2003, a collective research program under the eu-funded CRABCoordinator, joint "European aquaculture association", "European Union aquaculture producers" 23 from Norway, Ireland, England, Holland, Belgium, Spain and Portugal's partner, breeding sea fishing nets of fouling organisms in Europe has carried on the comprehensive survey, each year only for fish and shellfish forward maintenance cost an estimated $260 million. The group plans to provide excellent nets antifouling technologies for aquaculture, mainly including biological control (using natural food animals), non-toxic low surface energy antifouling coatings, electrolytic chemical effective method to control fouling organisms such as adhesion, can reduce the production cost of breeding 5% ~ 10% every year.

3. The status quo of anti-pollution technology of domestic fishing nets.

To solve the problem of anti-fouling of fishing nets in China, use artificial or mechanical scrubbing and scraping, or transfer the nets to the surface of the water or on the land to accept the sun exposure to kill the dirt. In this way, the amount of work, the number of repetitions, the damage to the net box and the breeding period of the seafood are also affected, and the method is not suitable for the anti-fouling treatment of the deep-sea net box. Now the government in the vigorously support the development of deep sea aquaculture [6], deep sea area diameter, large capacity, long, deep sea, greatly expand the breeding room, live seafood area from shallow to deep sea, free space changes from small to big, from near to far better water quality at the same time, various aspects have raised the breeding rate and survival rate of life; In addition, the breeding space becomes larger, the type of culture is increased and the quantity is expanded, so as to improve the breeding efficiency. It also develops deep-sea farming, reduces coastal pollution, promotes ecological environment and enhances urban image. Deep-sea farming can also be part of the tourism industry. Therefore, the deep-sea net box needs to be protected for a long time, which will reduce the frequent change of network, improve the utilization ratio of the net box and increase the production of seafood. And coating antifouling paint is one of the most effective and common methods to solve Marine pollution.

The present situation of antifouling paint for fishing nets.

The development and application of antifouling coatings for fishing nets are successful in Europe and Japan, and are mainly imitated in China and still in the research and development stage. At present, the antifouling coatings of fishing nets are mainly divided into two categories: one is the anti-fouling coating of antiseptic fishing nets; The second is the antiseptic fishing net antifouling paint (or the low surface can be antifouling paint). The antifouling paint containing fungicide is used in the current market and has a good effect. The antifouling coatings of fishing nets without fungicides are mainly in the development and promotion stage.

4.1 anti-fouling paint for fishing nets containing fungicides.

4.1.1 DDT fishing net antifouling paint.

The first fishing nets of antifouling coatings is [1], the former democratic Germany in the early 1960 s, is developed by DDT nets antifouling coating, antifouling agent and the effect is very good, application spread faster; The coating is toxic and accumulative, and it is harmful to environment and construction personnel.

4.1.2 anti-fouling paint with tin fishing net.

Organic tin has a wide spectrum and high efficiency for Marine pollution, and was widely used in Marine antifouling coatings in the 1960s. With the advent of organic tin self-polishing antifouling paint, it is also used in the antifouling of fishing nets. Organotin, polishing antifouling paint is in seawater by chemical reaction (type ion exchange and pure water solution) to achieve coating and polishing, since good smoothing effect on the surface of the coating, can obviously reduce the nets on sediment and algae and other sea creatures, and sediment is a hotbed of many microorganisms larvae, fundamentally solve the adhesion of sea creatures, which extended the antifouling coating ".

The commonly used organic tin includes tri-butyl tin oxide, tri-butyl fluoride tin, triphenylchloride tin, and tin copolymer. Organic tin self-polishing antifouling paint has good antifouling effect, and has been widely used since the 1970s. For example, the anti-fouling paint of the Flexgard fishing net produced by Flexbar company in the UK is the antifouling agent of tributyl tin (TBTO). Gug lielmoSr development of organotin nets antifouling paint to SanZheng TBT linoleic acid ester as antifouling agent, the dosage of 3% ~ 6% (mass fraction), the coating controlled polishing rate, good flexibility, wear resistance, after the baptism of 22 weeks sea bubble net test, 43% increase in net weight, stained area about 10% [8]. In the 1980 s the original chemical institute for the development of the fishing nets antifouling paint Marine coatings, the development of NC - 04 nets with 6 ~ 12 months of antifouling coating ", is organic tin as the main anti-fouling agent.

4.1.3 wuxi fishing net antifouling paint.

However, in the 1980 s found that the organic tin lead to fish on the morphological and physiological variation, at the same time some edible creatures such as oysters, crabs accumulate in the body, cannot be cooked remove [9-10], human once eating plenty of organotin contamination of fish, shrimp, shellfish and other walking function occurs and liver disease [11]. Therefore, the international maritime organization (MIO) proposed that organic tin [12-13] should be used in all antifouling coatings by 2008. The paint production company has introduced the non - organic tin low - toxic fishing net antifouling paint. The antifouling coatings for antifouling agents have been successively appeared in cuprous oxide and pyrithione copper. For example, Hard Racing Red of international coating company is the antifouling agent of cuprous oxide; International Fish Net A/F XKR159 Red is also A high-performance wuxi fishing Net antifouling paint, which can prevent pollution for up to 6 months. BIOGUARD and BIOCHRISTY are two series of antifouling coatings in Japan, including BIOGUARD with solute copper salt as antifouling agent and BIOCHRISTY as antifouling agent with organic sulfur. HEMPEL Net Antifouling 715GB Antifouling paint; The anti-fouling effect of these antifouling coatings is 3 ~ 6 months [8].

Marine chemical industry research institute Li Xuchao etc. [14] adopt elastic emulsion as the matrix resin, add the cuprous oxide, compound with organic antifouling agent nets antifouling coatings was prepared, through the test of practical screening, the anti-fouling "reached 7 ~ 10 months. The water-based silicate anti-fouling coating has good flexibility, excellent anti-fouling performance and low economic cost, so it has a strong competitive advantage in the antifouling of fishing nets. Shi Hang of east China sea fisheries research institute, etc. [15] chose a system of water soluble resin as basic material is given priority to with alkaline silicate, sodium silicate antifouling agent, zinc oxide to control the release rate of sodium silicate, and sodium silicate to form collaborative antifouling effect, has carried on the do not contain toxic materials environmental protection effective antifouling paint preliminary study, obtain certain antifouling effect. And Marine chemical industry research institute Wang Huajin etc. [16] also began to develop the nontoxic silicate antifouling coatings, adopt and nontoxic silicate antifouling agent Preventol A6 and pyridine copper sulfide ketone two anti-fouling agent, show better anti-fouling effect, which can effectively prevent adhesion of crustaceans and algae and aquatic life. The water-based non-toxic silicate anti-fouling coating was developed in the north sea for 12 months and the anti-fouling effect was obvious.

4.1.4 antifouling paint with natural product antifouling agent.

Adding chemical class antifoulant antifouling coatings, is poison is expected to release as the main way, in the process of using the class antifouling paint to the Marine environment pollution is serious, has side effects to the breeding of seafood. Now for a variety of plants, Marine animals, and Marine microorganisms was studied, and obtain a series of antifouling activity of natural products, including hot compounds, eucalyptus extract, organic acid, inorganic acid, lactones, terpenoids, phenols, sterols and indoles natural compounds (17-18). As a stable alkaloid, it is not affected by temperature. It has the function of antibacterial and exorcising the Marine life. Compared with chemical coating additives, the antifouling coatings of morin do not contaminate the attached organisms and cause biological variation, nor destroy the Marine food chain or cause the water pollution. From the perspective of environmental protection, the antifouling coatings of horseradish have a broader development prospect [19]. Vanilla pelargonic acid amide (PAV) belong to one of the hot element, can rely on its own strong spicy and pungent, have very good antifouling effect of dalian university of technology QuYuanYuan [20] is resin as film forming matter, adding 5% of PAV antifouling agent and composite plasticizers phthalates dioctyl ester (DOP), chlorinated paraffin, made the safety cages of non-toxic antifouling coatings, hang sample after 3 months of sea, net weight is only 3%, the results show that antifouling effect is obvious.

Marine natural products antifouling agent belongs to the non-toxic antifouling agent, is a Marine life itself have anti-fouling active secondary metabolites, these natural compounds can quickly degradation, and no harm of biological life, is beneficial to maintain the ecological balance, therefore, research of Marine natural products antifouling agent has become one of important way to obtain highly effective non-toxic antifouling agent.

2. No antiseptic coating for fishing nets - low surface anti-fouling paint.

From an environmental point of view, people always want to use pollution-free antifouling technology, realize the fishing nets to remove fouling organisms, low surface free energy of antifouling coating is in using coating of low surface free energy and water contact Angle, the liquid is difficult to spread out on the surface without infiltration, so as to achieve the aim of preventing Marine biofouling. At present, the low surface energy coating has been used to prevent fouling in the bottom of the ship, which has achieved good results, but it has not been used for anti-fouling of fishing nets. The east China sea fisheries research institute of Shi Hang [21] by adding liquid coating finishing polytetrafluoroethylene (PTFE) and capsaicin as antifouling agent, developed a new type of low surface energy antifouling coatings, the use of the synergy of the two, so as to prevent the effect of Marine fouling organisms attached. China's aquatic products research institute lu-min wang [22] also conducted in its patent CN1772826 Marine area net low surface energy antifouling coatings preparation, the polyurethane and curing agents DN - EB as film-forming material, adding 20% ~ 30% ptfe, made of low surface energy antifouling coatings fishing net. After 12 months of experiment, the biological adhesion area was 30% ~ 40%, which showed that the coating had better antifouling performance on the fishing net.

Cheng ningning [23] of dalian jiaotong university carried out the experimental study on the antifouling paint of the net box with low surface energy coating and alkaline silicate antifouling agent. With castor oil, glycerine and toluene diisocyanate as raw materials to synthesize polyurethane prepolymer, with hydrolysis chlorosilane preparation containing hydroxyl polysiloxane, then combination, made of polyurethane organic silicone film-forming substances, then alkali type calcium carbonate, sodium silicate antifouling agent to join the film-forming material system, the system of the fishing nets antifouling coatings. The results of measurement and the release of antifouling agent indicate that the antifouling coating has anti-fouling effect, but it has not been tested. The research and development of low surface energy antifouling coatings fishing net cost is higher, and must be a new fishing nets, an old fishing nets not appropriate, if the sea creature firmly adhere to the low surface energy nets antifouling coating, it is hard to processing, not suitable for popularization and application.

Development trend of antifouling paint of fishing nets.

With the global emphasis on sustainable development and the development of deep-sea network box development, it is the direction of future development to develop a long-term environmental protection coating. The development trend in the future is mainly reflected in the requirements of matrix resin and antifouling agent, and the development of synthetic adhesion, water resistance, abrasion resistance and flexible resin; The development and development of safe and non-toxic, efficient, broad-spectrum and stable fungicides, the development of low-toxicity, non-toxic, long-term fishing nets anti-fouling paint is the most promising development direction.