Advances in research on low-toxic and non-toxic anti-fouling coatings

Zhao Jinping (Shanghai
Coatings
Institute, Shanghai 200062)
Summary: One of the most economical, convenient and effective ways to prevent marine organisms from attaching is to use anti-fouling coatings. This paper introduces the traditional anti-fouling coatings and organo tin self-polished anti-fouling coatings, and summarizes the research progress of low-toxic and non-toxic anti-fouling coatings.
key words: marine defaced organisms; Low-toxic anti-fouling coatings; Non-toxic anti-fouling coatings; Decontamination paint; Non-stick paint; Research progress
in the figure classification number: TQ630.7 Document identification code: A article number: 1009-1696 (2012) 12-0024-06
0 Introduction
bottom, navigation float Standards, sonar devices, sea water cooling tubes and other contact structures with seawater will attach to a variety of sea creatures, initially formed by bacteria, diatoms, algae spores and other complexes, followed by barnacles, kaleidoscopes , clingworms, muffled animals, sponges and algae and other sea creatures attached to growth here.
the attachment of marine organisms will bring many problems to various offshore facilities. As far as the ship is serious, it makes the smoothness of the bottom of the ship become rough, thus increasing the frictional resistance of the hull navigation, usually, after six months of navigation, due to the attachment of the sea creatures at the bottom of the ship, so that the frictional resistance of the hull increases, to maintain the same speed, fuel costs increase, and to remove these attached sea creatures, and then coating and use costs in the dock during this period more. And a ship docked at sea after six months, because of the attachment of marine organisms, its speed will be reduced by 3.9%, fuel costs increased by 8.2%; A year after docking, the speed was reduced by 10.7 per cent and fuel costs increased by 25.5 per cent.
most economical, convenient and effective way to deal with marine organisms is to use anti-fouling coatings.
1. Traditional anti-fouling
traditional anti-fouling coatings are Cu2O-based anti-fouling coatings, including dissolved and contact type two types. Among them, the anti-fouling period of dissolved anti-fouling coatings is generally 8 to 14 months, while the anti-fouling period of contact anti-fouling coatings is generally 12 to 22 months, or even as high as 2 to 3a. However, this kind of anti-fouling coating is only effective for crustacean sea creatures such as barnacles, and the anti-fouling ability of algae sea creatures is insufficient, and this kind of anti-fouling coating is greatly affected by sea water temperature, pH, salinity and ship speed, often due to excessive leakage of Cu2O and make the coating waste, and reduce the anti-fouling period.
the 1960s, the use of organotin compounds, especially T-butyl tin compounds, greatly improved the anti-fouling effect of traditional anti-fouling coatings. Due to the broad-spectrum and high-killing biological effects of TBT on marine organisms, this diffuse anti-fouling coating combined with TBT can increase the anti-fouling period to 5a.
2. Organotin self-polishing anti-fouling coating
the diffusion anti-fouling coating using Cu2O combined with TBT compounds, although the anti-fouling period has been improved, but its permeation rate is 6 times higher than the required anti-fouling dose, so it can not use anti-fouling agent economically and effectively. Attempts were made to control the oozing rate of organo tin from a chemical structure by sealing the anti-fouling agent with a closed substation, such as epoxy or lacquer phenol resin, to allow the anti-fouling coating to seep out of an effective anti-fouling dose. In 1974, the british patent 1457590 proposed the T-butyl tin self-polishing co-polymer technology. The tropony tin self-polishing anti-fouling coating is based on an acrylic polymer (usually methyl acrylates) with a tetrate tin-based group bonded to the acrylic polymer main chain by ester-based bonding, as shown in Figure 1.
Figure 1 Chemical structural schematic diagram of methyl acrylate tributyl tin and methyl acrylate copolymers
After the coating is immersed in seawater, the soluble pigment particles in the coating begin to dissolve in seawater, while the methyl acrylatetin and methamphetamine copolymers in the coating are dredging Water, can prevent seawater from penetrating into the coating film, so that seawater can only seep into the soluble pigment particles dissolved after the resulting gap, in slightly alkaline conditions, the hydrolysis of the nicotine-Tbutyl tin binding is unstable, so that part of the tributyl tin group and acrylic co-polymers have a controlled hydrolysis reaction (see Figure 2).
Figure 2 Diagram of controlled hydrolysis reaction of TBT copolymers
after that the sea slowly dissolves more anti-fouling particles and expands the reaction range (leakage layer), once a sufficient amount of TBT is partially released from the coating surface, the main chain of the partially hydrolyzed polymer is eroded by the flowing seawater and exposed to a less hydrolyzed coating surface (self-polishing effect). After a period of time, the anti-fouling agent particles produced by the dissolution of the anti-fouling agent move forward, and through the ion diffusion of the seepage layer, the diffusion rate is equal to the erosion rate of the substing, thus achieving a stable oozing layer thickness, which has been stable and low value (10 to 20 m) during the life of the coating. This self-polishing effect provides the ship with a low roughness (approximately 100 m) during ship navigation, saving fuel and reducing CO2 emissions. The polishing rate of a typical T-butyl tin self-polishing coating is 5 to 20 m/month. The main advantage of this coating system is that it controls the hydrolytic rate of compounds (polishing rate and rate of release of biocides) for the most efficient service life. Therefore, different anti-fouling coatings can be designed according to the ship's different speed, such as high-speed ships can use slow-polish anti-fouling coatings, while slow-moving ships can use fast-polished anti-fouling coatings. Self-polishing coatings based on tridyl tin co-polymers can maintain a 5a anti-fouling period without re-painting, because its permeation rate during use is almost constant, and because of the self-polishing effect of this coating, can save considerable fuel and reduce more CO2 emissions, so in the 1980s, 60% to 70% of the world's ships used this kind of self-polishing anti-fouling coatings.
3. Low-toxic self-polishing anti-fouling coating
Although T-butyl tin compounds are not harmful to the human body, however, some people who have been exposed to such compounds for a long time have experienced abnormal abnormal phenomenon of elevated brain pressure, but also the appearance of skin discomfort symptoms, if appropriate protective measures, such phenomena and symptoms can be avoided. Since the design of T-butyl tin compound anti-fouling coatings at that time only took into account the harm to the human body and did not take into account the impact on the surrounding environment, but at present its harmful consequences have been revealed, such as the Indian Ocean, the Atlantic Ocean and the Pacific Ocean and other sea areas have serious organic tin compound pollution, they in water and sediments in the long-term and long-lasting toxicity, resulting in marine life mutilation, delay their growth, and through their food chain into their bodies caused biological accumulation. The base tin compound can deform the oyster crustacean, cause the sea biological change (sexual distortion) of the screw, delay the immune response of other sea organisms, cause neurotoxicity and bad genetic effects, etc. To this end, the International Maritime Organization (IMO) has decided to ban the use of organo tin compounds as anti-fouling agents as of 1 January 2008.
To this end, people have invested a lot of money, human research and development of Wuxi anti-fouling coatings, so far there are two types of anti-fouling coatings to achieve commercialization:
(1) controlled erosion system (CDPs), the use of modern reinforced resins to improve the traditional dissolved anti-fouling technology, its mechanism of action and traditional anti-fouling coatings based on pine incense the same;
(2) Wuxi self-polishing co-polymer (Wuxi SPC) has the same role as TBT self-polishing (SPC) coatings in seawater.
the characteristics of this type of self-polishing coating are as follows:
(1) when sailing, the appearance of a smooth coating surface;
(2) thin and stable seepage layer, producing a continuous and constant rate of permeation over time (at fixed ship speed and sea water conditions);
(3) polishing rate allows anti-fouling coatings to appear active at rest and increase linearly with the speed of navigation.
of these properties, anti-fouling coatings have long-term activity and effective service life (e.g. 5a), and the bottom of the ship has a good fluid shape, playing a role in reducing fuel consumption.
of these anti-fouling coatings products are available at
, a leading international
coating company:
(1) AkzoNobel (subsidiary Internatio
nal Marine Coatings)
AkzoNobel has three anti-fouling coatings products: Interclene245, Interspeed340 and Intermoth Ecoloflex SPC. Soon, interswift655, a hybrid anti-fouling coating product between CDPs and SPCs, will be launched. Intersmooth Ecoloflex SPC has been patented for self-polishing copolymers based on acrylic polymers containing unknown organic-based copper salts.
acrylic copper polymer hydrolytic reaction in seawater
early paper reported that acrylic copper coating has up to 3a anti-fouling period, after improvement is said to be anti-fouling period of up to 5a, the actual use of the effect shows that its anti-fouling period of 42 months. When two ships coated with Intersmooth EcoloflexSPC anti-fouling paint sailed 5a and docked, their anti-fouling performance was good from the photos. The company claims that the coating's anti-fouling effect is comparable to that of TBT SPC coatings.
(2) Kansi Coatings Co., D.C.
The company's main anti-fouling coating product is "Exion", which is acting on the release of zinc-containing side-based properties bonded to the main chain of acrylic polymers. This action is very similar to copper acrylic coatings, the action of the following:
polymer reactive
zinc acrylic polishing depends on the impact of this substation reaction of zinc acrylic content and copolymer hydrophobic (affecting the absorption of water). Because the content of zinc acrylic increases, the flexibility of the coating decreases, so it is difficult to meet the requirements of the real SPC anti-fouling coating, so it is d'eminention monomer to be modified. To this end, several types of zinc acrylic/ zinc acrylic ratio, different types of zinc acrylic copolymer monomer monomer and a clear percentage of acrylic methyl ethyl monomer tested, resulting in the approximate composition of the coating.
(3) Jotun
Company's Sea Quantum anti-fouling coating series, based on acrylic methylene silicane polymer, can achieve a controlled permeability rate of bio-killer agents, the formula also contains pine incense for oozing. In the seepage layer of this type of anti-fouling coating, the sea water slowly acts with the active polymer and releases R3SiCl, which acts similar to the TBT SPC anti-fouling coating:
(4) is coated with marine coating company
the company produces anti-fouling coatings, in addition to the three-year anti-fouling period of the Sea Grandprix 500/700 anti-fouling coating series, there is also based on The SeaGrandprrix 1000/2000 anti-fouling coatings series of acrylic methylsilane esters act in a similar manner to Jotun's Sea Quantum anti-fouling coatings series, whose polymers may be mainly methyl acrylates and metformin tripropyltin, as well as a large number of chloroflucoxic waxes (which improve crack resistance and peeling resistance) and dewatering agents (improved storage stability). Recently, silicone components have also been modified, possibly based on acrylic triopropyl silicate and methyl acrylates or acrylic triopropyl silicate, tributyl acrylic and methyl acrylates have been the third generation of products.
(5) Hempel's Marine Paints
is currently committed to the use of fibers in anti-fouling coatings, its fiber preferably length of 50 to 300 m, the average thickness of 2 to 10 m, the average length to average thickness ratio of at least 15, and the use of natural pine synthetic substitutes, so that anti-fouling coatings are more stable, less oxidation sensitivity, and have suitable sea water solubility. It continuously reacts to form zinc hydrate, which not only improves hardness and shortens drying time, but also produces controlled release performance through "ion exchange", which works as follows:
This anti-fouling coating also uses polymer substrings (Tg>25 degrees C) as an added Plastics to provide flexibility, the choice of oils, saturated polyester resins, aolate resins, hydrocarbon resins, chlorinated polyolefins, etc., and the use of fluidizers
bend soil
, as well as amorphosic polymerization tougheners. According to Hempel, the coating's unusual mechanical properties, controlled polishing properties tailored to different requirements, good re-coating, low VOC (volatile organic compounds) content and fine roughness are similar to organo tin anti-fouling coatings.
(6) PPG's Sigma Coatings
company's anti-fouling coatings product name Alphagen, its technology is based on Sigma developed and produced a unique resin, its polishing performance is similar to the company based on Sigmplane HB, the company's polishing rate of 5 to 6 m/month. The coating is soaked in natural dutch seawater for 57 months without defacation.
It should be noted that these Wuxi anti-fouling coatings rely only on agents such as copper and zinc to resist broad-spectrum marine defacement of organisms, because the toxic agents to marine organisms is the agent of its protein precipitation, or poisoning its stomach, and organo tin compounds poisoning of marine organisms is to destroy their metabolism or make it neurotoxic. Therefore, the above anti-fouling coatings also need some auxiliary agents to expand its broad-spectrum killer biology, such as AkzoNobel's Intersmooth EcoloflexSPC using zinc pyrithione, Interspeed340 using ethyl double-sulfur zinc, Interswift655 using ethyl-bidithione zinc or pyrithione copper; Jotun's Sea Quantum uses copper pyrithione; Hempel's Global81900-81970 uses 4,5-dichloride-2-zhengxinki-3 (2H)-isopyrosterone or pyrithione copper; Sigma's Alphagen 10-20-50 uses isoproidone, etc.
Others that have been approved by the United States, the European Union, the United Kingdom, Australia or Japan and can be used as anti-fouling biological agents for the above-mentioned anti-fouling coatings are: 2-methyl thiopental-4-butamine-6-cyclophamphetamine-s-triamolin, 2,3,5,6-tetrachloride-