Coating classification: antifouling coating

Core tip: Introduction: Antifouling coating is also called antifouling coating Antifouling resistance refers to the degree of difficulty of pollutants on the surface of the coating after it is stained by dust, atmospheric suspended substances and other pollutants Antifouling functional coating is a new type of functional coating which is not easily stained by dust and other pollutants, and its surface is easy to clean Antifouling coating is mainly used in construction industry, shipbuilding industry, etc Form: Antifouling coating mainly consists of five components: resin, antifouling agent, auxiliary material, filler and solvent Antifouling coating is formed when it is applied to the surface of the object to form a film Among them, the commonly used resins are Shenyang steel structure fireproof coating construction expert punde Building Fire Engineering Co., Ltd Recommended introduction: since its establishment, Shenyang punde Construction Fire Engineering Co., Ltd has cultivated a group of professional construction teams with excellent equipment, rich experience and serious responsibility with advanced and scientific management methods and strict engineering quality assurance and after-sales service system It has undertaken a number of fire system installation projects, which has been praised by customers Every idea and special requirement of you will be fully considered by us and fully realized in the construction technology, which will become the cornerstone of our successful long-term development We are looking forward to your invitation, to provide you with quality services and high-quality technical support! All construction coatings have passed ISO9001 Paint Home News: Introduction: antifouling paint is also known as stain resistant paint Antifouling resistance refers to the degree of difficulty of pollutants on the surface of the coating after it is stained by dust, atmospheric suspended substances and other pollutants Antifouling functional coating is a new type of functional coating which is not easily stained by dust and other pollutants, and its surface is easy to clean Antifouling coating is mainly used in construction industry, shipbuilding industry, etc Composition: antifouling coating mainly consists of five components: resin, antifouling agent, auxiliary material, filler and solvent It is an antifouling coating when it is applied to the surface of an object to form a film Among them, the commonly used resins are chlorinated rubber, vinyl chloride acetate copolymer, epoxy resin, acrylic resin, etc.; the commonly used antifouling agents are cuprous oxide, cuprous thiocyanate, zinc oxide, cupric sulfate, copper powder, cupric naphthenate, organotin, DDT, chlorothalonil, 2-methylthio-4-tert-butylamino-6-cyclopropylaminotriazine, diuron, 4,5-dichloro.2-n-octyl-4-isothiazoline -3-ketone, zinc pyridyl thioketone, etc.; commonly used auxiliary materials are: iron oxide red, rosin, talcum powder, titanium dioxide, dioctyl phthalate, tower oil, Trimethylphenol phosphate, Vaseline, chlorinated paraffin, etc.; commonly used organic solvents are xylene, butyl acetate, ethyl acetate, butanol, cyclohexanone, etc Among the five components of antifouling coating, resin and antifouling agent are the key components to determine the performance of antifouling coating Antifouling agent is the main toxic material for antifouling coating to prevent biological adhesion, and resin is the carrier for antifouling agent to achieve antifouling performance Therefore, the development of antifouling coating technology mainly depends on the development of new resin and new antifouling agent Antifouling mechanism: there is a great relationship between biological fouling and surface energy The lower the free energy of the solid surface, the smaller the adhesion, the greater the contact angle of the liquid on the solid surface The paint has a very low surface energy, so it is difficult for marine organisms to adhere to it Even if the adhesion is not firm, it is easy to fall off under the action of water flow or other external forces The traditional toxic antifouling coatings can only inhibit some marine organisms With the release of toxic substances, the antifouling effect of the traditional antifouling coatings has gradually decreased Because the adhesion interface of the low surface energy antifouling coatings (also known as the non-toxic antifouling materials falling off antifouling coatings) is not always weak, they are used Self weight, impact of water flow during navigation or cleaning of auxiliary equipment can easily remove attachments More importantly, low surface energy antifouling coating is based on the physical function of the coating surface, without the release loss of toxic substances, and can play a long-term antifouling role At present, the low surface energy materials are mainly organosilicon series and organofluorine series Classification and performance: traditional antifouling coating is based on rosin adhesive, mainly using cuprous oxide as pigment Rosin binder will dissolve in water and release toxic pigments The problem of this kind of antifouling coating is that the decomposition of rosin adhesive is difficult to control and more serious Its protection against marine pollution lasts only 12-18 months Rosin based antifouling coating will react with oxygen, so the paint must be drained after drying, generally within 6-8 hours, but not more than 24 hours This kind of antifouling coating uses chlorinated rubber or ethylene as binder and a large amount of cuprous oxide as pigment In case of water, toxic paint will be released, leaving only empty shell of adhesive After a long enough time, the thickness of the empty shell will become very thick, so that the toxicity of toxins released into the thin water layer is insufficient, which is lower than the critical value necessary to avoid the growth of pollutants A large number of toxic pigments will remain in the antifouling coating system under the empty shell of the adhesive People test the way of removing the empty shell of the adhesive by underwater brushing Due to the problems of manpower, management equipment and inspection, this method is not effective Before the antifouling coating is constructed again, the empty adhesive shell on the dry dock must be sealed When the number of times of dry dock is enough, a thick "sandwich" system consisting of antifouling coating and sealing coating will be formed on the hull When the total dry film thickness is 1000-1200 μ m, this kind of sandwich system will produce great internal stress and spalling, resulting in very rough underwater shell The protective ability of the release antifouling coating against marine pollutants can be as long as 18-24 months This kind of antifouling coating is also called insoluble matrix antifouling coating This type of antifouling coating is based on a mixture of rosin and a blended binder, such as ethylene The pigment used is also cuprous oxide, plus a small amount of other biological pesticides In essence, the mechanism of ablative antifouling coating is similar to the pure traditional antifouling coating based on rosin, but the addition of mixed (or humidified) adhesive prolongs its decomposition process To some extent, the dissolving of adhesive avoids the accumulation of sandwich system, but there is a very thin saponification layer on the surface of ablative antifouling coating The structure of adhesive shell on the surface of ablative antifouling coating is similar to that of release antifouling coating Ablative antifouling coating can resist marine pollution for up to 26-30 months There are two types of self polishing antifouling coatings in the self polishing Antifouling Coatings Market: tin containing type and Wuxi type (excluding tin) Tin containing type uses Tributyltin Methacrylate as binder In addition to tin, toxic cuprous oxide is also the main paint pigment, and other biological insecticides are often used to enhance the effect The hydrolysis of its adhesive has been described for a long time, but it must be pointed out that self polishing antifouling coating does not pile up to form sandwich system Self polishing tin containing antifouling coating can resist marine pollution for more than 5 years during navigation Wuxi type self polishing antifouling coating is designed to simulate the action mechanism of tin isobutyrate adhesive At present, Wuxi self polishing antifouling coating appeared in the market includes: zinc acrylate adhesive, zinc carboxylate adhesive, copper acrylate adhesive, silanized acrylic adhesive The main mechanisms of all the above technologies are hydrolysis and ion exchange The polymer itself is hydrophobic because it is bound to functional groups by an ester bond This means that when the polymer is immersed in seawater, the ester bond will break, leaving carboxylate to improve the hydrophilicity of the polymer It has been pointed out that the protection time of the new generation antifouling coating in Wuxi against marine pollutants can be as long as that of the tin containing antifouling coating But that remains to be seen This kind of antifouling coating is completely non-toxic It works on the principle of low surface energy, that is, it is difficult for the marine dirt to adhere to the coating surface This kind of antifouling coating is sometimes called the antifouling coating for pollutant release, most of which are based on silicone adhesive The unique surface properties of self releasing paint minimize the adhesion of dirt tissue All dirt that may adhere can be easily (relatively) washed out during operation or when entering the dry dock Many marine organisms, such as corals and sponges, can metabolize antifouling substances, so they can use their biological extracts as antifouling agents If sponge extract is used as antifouling agent, and siloxane resin, epoxy resin, polyester, polyurethane and fluoropolymer are selected as base materials, antifouling coating can prevent marine organism from fouling This is because the extract of sponge can interfere with the movement of tentacles of marine attached organisms, so that marine organisms are restrained at the initial stage of attachment Another theory is that the extract of marine organisms can interfere with the reception and transmission of adhesion signals, and the specific mechanism remains to be further explored In Japan, some people use powdered shells of bivalves or snails as antifouling agents If oyster shell powder, salamander shell powder and butadiene styrene copolymer are used to make solvent coating, the antifouling period is more than 1 year Many plants also contain natural anti adhesion substances, such as oak, eucalyptus, neem, potato, rhubarb and other plant extracts In the United States, such antifouling coatings have been exported to the international market Capsaicin extracted from capsicum is used as antifouling agent This antifouling agent has a very strong antifouling ability Capsaicin, as an antifouling agent, can be uniformly dispersed capsaicin, oil-containing resin capsaicin liquid solution, or crystal capsaicin Mixing the antifouling agent with anti-corrosion epoxy resin, adding a proper amount of curing agent, and applying it on the surface of wood, metal and plastic to be treated, can prevent the common organism fouling in fresh water and sea water In the port construction, it is found that the alkaline cement structure has no pollution in about one year Therefore, people use the alkaline silicate as the antifouling agent to prevent sea creatures from adhering by increasing the alkalinity of the seawater around the coating Typical coating compositions include cement 10%, CaCO3 60%, SiO2 5%, Ca (OH) 25%, vinyl acetate resin 20% The antifouling coating is cheap and nontoxic, has excellent antifouling performance, and has good sea water resistance and weather resistance It is generally believed that the suitable growth environment for marine organisms is slightly alkaline seawater with pH value of 7.5-8.0, which is not suitable for survival in strong alkaline or acid environment Other silicates (such as zeolite, i.e aluminosilicate containing crystal water) can also be used as antifouling agents The antifouling mechanism can be explained as an ion exchange or molecular sieve function Aluminosilicate carries out ion exchange with H + in sea water, releases antifouling ions, and plays an antifouling role A similar composition is prepared by adding aluminosilicate, Zn powder, Al powder, ZnO, BaSO4 and the like into the base material, and the antifouling period can be up to 1 year In addition, there are other examples of synergistic action of antifouling agent and silicate The main antifouling agent is silicate, with other antifouling additives, and the resin with good compatibility with silicate and certain self polishing ability (such as