The work is separated in biocides and binders for AF Paints:
Within task 1 a choice was made of four different classes of biocide compounds for further development in the project.
The composition of compounds in each class has been adapted interactively with the results of biological tests. These tests consisted of laboratory barnacle bioassays and microbiological assays (task 3).
In this way 204 compounds have been synthesised by various partners within task 2 and subsequently tested in task 3.
The most promising ones, in total 16 compounds, have been considered for further paint testing.
These tests involved:
- Incorporation in model paints and static exposure of panels with these paints in the North Sea and in the Mediterranean (task 5);
- testing some of this paints on anti barnacle properties by laboratory assays (also task 5);
- Performing a number of environmental tests within task 6. These tests have been specially developed or adapted to seawater conditions.
Finally, combining the results of all these tests with the physical and economical properties three different (groups of) compounds have been considered for further development in coatings and patenting. In particular, compound CAULB13 has been upscaled and applied at larger scale in model and company coatings for testing in situ: at various rafts and ships (activities within task 5).
From the positive results from tests on ships and at rafts at different locations around the world, in particular if formulated in a company related coating, it is concluded that compound CAULB13 so far appears to be the most promising one:
- satisfactory antifouling properties up to 26 months;
- relatively low toxic effects on non-target organisms;
- appropriate water solubility;
- simple synthesis and cheap, readily available starting material for synthesis;
- good compatibility with other paint constituents;
- good thermal stability.
For the new binders acrylic monomers with five different functional classes were synthesised. Two functional classes were chosen for scale up synthesis.
The following possibilities were performed to obtain new binders for antifouling paints:
- Polymerisation of the before mentioned acrylic monomers;
- in situ formation of new monomers during the polymerisation;
- chemical post modification of monomers with functional groups.
The binders chosen fur further evaluation have been tested on practical use in paints, water sensitivity and self-polishing properties. The water sensitivity and uptake was investigated as well.
The development and tests resulted in a limited number of binders, which have been tested in company related formulations. The tests focussed on self-polishing behaviour and exposure tests.
12 binders were upscaled and used for paint formulations. Long term performance of the formulated binders showed;
- a decreasing polishing rate with time;
- a tendency to cracking;
- a strong tendency to gelation during storage of the paint.
The binders have to be further improved on these properties.
The work performed during the project lead to a already prepared publication:
- Document on acceptability of AF;
Task 7- new test protocol for the evaluation of AF compounds;
- Environmental tests;
- Leaching test (participation at a ISO/ASTM working group);
- Barnacle test;
- Accelerated laboratory test.
Objectives and content
Biological fouling on constructions immersed in seawater (such as ships, seawater treatment systems, offshore platforms and fish cages) has large economic consequences. The most widely used method to combat aquatic fouling is the application of antifouling (AF) coatings containing biocides. Up to 80% of the currently used AF coatings contain tributyltin (TBT) as the active agent. Because of the unique self polishing properties - due to TBT organotin coatings have a very long servicelife. However, organotin is rather harmful to the environment and regulations to restrict the use of TBT containing AF coatings have been issued. World-wide biocide producers, paint industry and end-users are searching for alternatives, but the performance of currently available tin-free alternatives is considerably lower and the servicelife is much shorter.
In the frame of the European MAST 11 a number of natural compounds with AF properties, developed by marine organisms, have been elucidated. In the proposed project AF related industry, together with research organisations involved in the MAST project, aim to develop environmentally compatible AF coatings based on these compounds.
The project consists of the synthesis and evaluation of analogues, and the application of promising analogues in coatings. Selection criteria will be based on antifouling, toxicological and chemical/physical properties. The compounds will be developed in a continuous interaction between synthesis and laboratory testing. Optimalised compounds will be incorporated in experimental antifouling formulations and tested in the field. The risk to the marine environment arising from the use of the developed coatings will be assessed and compared with the risk of TBT coatings. The best performing coatings will finally be tested in practice, e.g. on test areas on ships and other submersed objects, in collaboration with end-users.
The challenging objectives of this project are to generate tools and knowledge to make the production of coatings with at least the same performance and technical properties as the organotin containing selfpolishing ones.The industrial partners of the consortium warrant the industrialisation of the results. Success of this project will be beneficial to the environment and human health and will be of essential importance to preserve or expand the market for the involved European industry.
Funding SchemeCSC - Cost-sharing contracts
47812 R 54 Krefeld
1780 AB Den Helder
1047 BB Amsterdam