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    Home > Coatings News > Paints and Coatings Market > A new breakthrough in marine antifouling!

    A new breakthrough in marine antifouling!

    • Last Update: 2022-04-17
    • Source: Internet
    • Author: User
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    For all kinds of instruments deployed in seawater for a long time, biofouling is a serious problem, which not only shortens the service life of the instruments, increases the frequency and cost of manual maintenance, but also may lead to drift of observation signals and data errors
    .
    Therefore, the exterior of the instrument must be antifouled

    .


    An introduction to marine biofouling

    Marine biofouling refers to the phenomenon of equipment damage caused by the attachment and erosion of fouling organisms in the ocean on the surface of materials
    .
    At present, there are about 5,000 kinds of fouling organisms known, including animals, plants and microorganisms.
    The more common ones are barnacles, mussels, seaweeds, etc.
    (as shown in Figure 2)

    .
    Some of them are adsorbed on the bottom of the ship, which increases the resistance of the ship when sailing and accelerates the corrosion of the metal on the bottom of the ship; some grow inside the metal pipeline, which is easy to cause blockage and leakage of the pipeline; some grow in offshore facilities surface, further accelerating the damage of the building

    .


    So how do marine organisms adsorb on the surface of the material? In fact, the attachment of marine organisms has gone through a complex process
    .
    As shown in Figure 3, in the initial stage, some organic molecules are adsorbed on the surface of the material to form a basement membrane, and at the same time, bacteria commonly found in seawater such as spirochetes, vibrio, cocci, and bacilli also adhere to the surface of the material.
    A layer of biofilm was built in days, laying the foundation for subsequent biological attachment

    .
    In the middle stage, small fouling organisms such as diatom spores, ciliates, bell-shaped worms, and nematodes are adsorbed on the biofilm, and the number is increasing

    .
    In the later stage, some algae that live by attachment are connected to the surface of the object through the colloid secreted by themselves, resulting in a sharp increase in their types and numbers, while the establishment of biofilm is the result of some mussels, barnacles and other large marine attached organisms on the surface of the material.
    Attachment lays the foundation

    .
    Therefore, people often effectively inhibit the biofouling problem by inhibiting the formation of biofilms

    .


    Due to the vast sea area of ​​our country, different sea areas have different pollution situations
    .
    In general, the severity of fouling in coastal areas in China shows a trend of increasing from north to south.
    This is due to the high temperature and open waters in southern China, which are conducive to the growth of various fouling organisms

    .
    At the same time, the attachment of fouling organisms also has obvious seasonal changes.
    Some organisms can attach throughout the year, while others are mainly concentrated in one season

    .
    Therefore, it is the most effective and convenient antifouling method to develop corresponding antifouling coatings according to the specific conditions of fouling

    .


    The history of antifouling coatings

    In ancient times, because ships were made of wood, drilling organisms such as ship maggots became the most important fouling organisms in ancient times
    .
    The ancients used asphalt, wax, and paint containing poisons to coat the surface of wooden boats to prevent ship maggots

    .
    In the Ming Dynasty, China had mastered the mature wooden boat anti-corrosion and anti-fouling technology, which enabled Zheng He to go to the Western Ocean seven times

    .
    With the advent of the modern industrial revolution, steel-hulled ships have been facing two major challenges of seawater corrosion and biofouling since their invention

    .
    By the Second World War, fouling organisms had attracted great attention because of their damage to warships, underwater installations, and weapons

    .
    In the following decades, marine antifouling coating technology has developed rapidly

    .


    Before the liberation of China, antifouling coatings were mainly imported from Europe
    .
    In the 1950s, China's paint factories have started independent research and development of antifouling coatings

    .
    Although these coatings have problems such as short antifouling period, poor antifouling effect, low output and few varieties, this has laid a solid foundation for the development of antifouling coatings in China

    .
    In the 1960s, due to the anti-fouling needs of our navy ships, our country began to carry out a lot of research work on anti-fouling coatings such as asphalt, vinyl resin, chlorinated rubber, acrylic resin and epoxy resin

    .
    After 15 years of hard work, the aluminum-hulled speedboat paint and steel-hulled warship paint developed by our country have reached the world's advanced level in the variety and quality of ship paint

    .


    The advent of tin self-polishing antifouling coatings in the 1970s quickly captured most of the antifouling coatings market
    .
    The coating can be slowly hydrolyzed under the action of seawater, constantly renewing the coating surface, which is not conducive to the attachment of marine organisms, and at the same time, the organic tin compound released has certain toxicity, which can effectively kill the attached organisms

    .
    However, because organotin compounds are highly toxic and difficult to degrade, causing marine pollution and destroying the ecological balance, many countries have banned the use of such coatings

    .


    3.
    CPT-based antifouling coatings

    The current mainstream antifouling coatings include self-polishing antifouling coatings, low surface energy antifouling coatings, natural product antifouling coatings, and bionic antifouling coatings
    .


    Recently, the latest research by the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences (hereinafter referred to as the Shenzhen Institute of Advanced Technology) and Xiamen University has brought some anti-fouling tips
    .
    The researchers studied the anti-fouling performance of natural product-based anti-fouling coatings on 6 kinds of commonly used marine sensor metal and non-metal materials through long-term marine experiments in the subtropical sea areas of Xiamen and Shenzhen

    .
    Relevant research results were published in International Biodeterioration & Biodegradation

    .


    Applying antifouling paint to the surface of the in-situ instrument shell material is one of the main methods to reduce biological adhesion, but the existing antifouling paint is often highly toxic, which not only pollutes seawater, but also may cause damage to the biological objects being monitored.
    However, some other low surface energy coatings have poor static antifouling effect and are not suitable for sensors statically deployed in seawater

    .
    In response to these problems, the Shenzhen Advanced Institute and Xiamen University team cooperated to study the antifouling performance of natural product camptothecin (CPT)-based antifouling coatings on instrument housings of different materials in a subtropical sea area

    .


    In the study, the researchers made 316L stainless steel, TC4 titanium alloy, 7075 aluminum alloy, polyoxymethylene, polyvinyl chloride, Teflon 6 kinds of commonly used marine instrument shell materials into hanging boards, and placed them underwater in Xiamen's Wuyuan Bay.
    To test the antifouling performance of CPT-based antifouling coating on the surface of the above materials

    .


    The sea test results showed that the CPT-based antifouling coatings showed excellent anti-biological adhesion performance on the above 6 materials within 3 months.
    clean

    .
    After 9 months, the coated areas still had significantly less fouling organisms than the control areas, with the plastic material showing better biofouling performance than the metal material

    .


    In addition, the two parties also conducted a sea test of the antifouling efficacy of CPT-based antifouling coatings on three in-situ sensors developed by the Shenzhen Advanced Institute team
    .
    The buoy sea trial results show that when the CPT-based coating is used for the underwater in-situ sensor, the surface of the in-situ sensor housing can be kept clean for at least 4 months; compared with the case without coating treatment, the maintenance-free period of the sensor is greatly extended

    .


    It is reported that this technology not only reduces the labor cost of marine instrument maintenance, but also enhances the reliability of the sensor working in the marine environment
    .
    CPT-based coatings can be used as an effective anti-biofouling solution to enhance the long-term underwater performance of marine instruments in real marine environments

    .


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