Review
Marine paints: The particular case of antifouling paints
Introduction
It is fairly common for the area of anticorrosive protection painting (APP) to be underestimated by specialists in other areas of science, such as electrochemistry or biology. Painting, ancestrally known for its empiricism, brings a frown to the face of many specialists, who have nevertheless not had the opportunity to discover the complexity and the interdisciplinarity of APP in recent decades. An excellent example of this reality can be seen in the case of marine paints [1], [2], [3], [4], [5], as will be shown below.
A structure like a large ship in itself offers a wide range of exposure conditions, giving rise to a complexity and diversity of anticorrosive protection situations that need to be resolved. These include areas such as the hull, deck, superstructures, fuel tanks, ballast tanks, and others. In turn the hull presents different parts with highly specific operating conditions, going from the ship bottom (permanently immersed in sea water) to the boottop area (subject to alternating immersion conditions), splash area (above the water line with the ship fully loaded), and the top sides (which are practically always emersed and exposed to the atmosphere).
In view of the variety of the problems it poses, the underwater part of the ship is the most interesting area for the APP specialist. Besides the need to assure efficient anticorrosive protection painting that is compatible with cathodic protection, it is also necessary to keep the surface as smooth as possible in order to minimise drag resistance when the ship is in movement and thus reduce fuel consumption [6], [7], which means the need to prevent the attachment of a wide variety of marine organisms, both plants (flora) and animals (fauna). Furthermore, in recent decades the antifouling paints applied on ship hulls must not only prevent the fouling of underwater areas but must do this in compliance with emerging regulations and legislation [8], [9], [10], and furthermore are required not to release biocides into the sea water. Thus, a fight against time is on (demanded by the International Maritime Organization, IMO) [10], in an ongoing search for practically “miraculous” antifouling products.
Following a short review of marine paints in general, the present work makes a systematic analysis of the specific problem of interaction between ship hulls and sea water and the antifouling technologies used on ship hulls from historic times to the present day. Reference is also made to other alternatives to painting that have emerged in recent decades, and an indication is given of some promising ways that are currently under development, and which may in the near future lead to antifouling paints that can be used after the complete banning by the IMO [10] of existing efficient antifouling paints that are still in use. The latter, which are the fruit of in-depth research carried out over many years, can now be practically tailor-made [11], [12], [13] in accordance with the particular characteristics of each type of ship.
Section snippets
Short review of marine paints
Contrary to the past, in recent decades the anticorrosive protection of steel ships starts in the shipyard, which is now normally equipped with automatic blasting and painting plants for both steel plates [14] and steel profiles. Here, the different steel surfaces are blasted and painted with shopprimer [15], in accordance with the ship's construction schedule. Following a suitable drying time, the prepainted plates and profiles pass on to the plateshop where, depending on the ship's design,
Protection of underwater ship parts
It is mandatory that protective painting systems for underwater ship parts include an anticorrosive primer and an antifouling topcoat. Sometimes a suitable tie coat is applied between the primer and the antifouling paint, especially when the anticorrosive primer contains components that may negatively affect the adhesion of the antifouling paint; e.g. in the case of primers containing coal tar, which tend to exude towards the antifouling, affecting its efficiency, or in the case of short
More environment- and man-friendly antifouling paints
Due to the environmentally harmful action of the well known, efficient and versatile TBT self-polishing paints, and the consequent prohibition of their application after 1 January 2003 and of their presence on ship surfaces after 1 January 2008 [9], [10], paint manufacturers have been forced to urgently study and develop new more environmentally friendly antifouling paints. Without seeking to be complete or exhaustive, the products with biocides that have recently been marketed for this purpose
Conclusions
Since remote times Man has been fighting a never-ending battle against the fixing of marine organisms on surfaces immersed in sea water in general, and on ship hulls in particular. Even when the problem seemed to have been solved, thanks to the boom in the development of TBT-based antifouling paints, with their well-known technology in which, by suitably controlling the molecular composition of the binder, it was practically possible to tailor-make antifouling paints to meet the needs of each
Acknowledgements
The authors wish to thank Hempel Portugal and Chugoku for their contribution with the same figures used in this paper.
References (148)
-
Sci. Total Environ.
(2000) -
J. Coat. Technol.
(2002) -
Ind. Eng. Chem. Res.
(2002) - et al.
POC
(2004) -
Anal. Chim. Acta
(2002) - et al.
Chemosphere
(2002) -
Sci. Total Environ.
(2000) -
POC
(2002) -
J. Exp. Mar. Biol. Ecol.
(1996) -
Shipbuiding Progress
(1986)