Coating Hazards
Designers must consider Biodegradability, Toxicity, Health, and Safety of coatings when selecting a product. In recent years biocides based on heavy metals such as Tributyltin (TBT), which have a high toxicity, have been banned by many countries due to harmful effects on marine organisms in ports and harbours. As a result, there has been a shift to a range of antifouling materials. One of which, copper, has already been banned in California and the Netherlands. Some examples of biocides follow.
Biocides
- Cuprous Oxide
- Copper Thiocyanate
- Sea-nine
- NB17
- Zinc Pyrithione
- Irgarol
- Diuron
Polymers
Polymers are a common attribute found in all marine coatings. Many variations of this petroleum based product exist. Epoxy polymers have been essential in the controlled release of biocides found within marine antifouling coatings. New products entering the market continue to use epoxy while others are using polymers such as fluoropolymers, nylon and silicone. Although this material does not kill marine organisms instantly, it should be taken into account that this is a non-biodegradable material that can be consumed by marine organisms. Once the coating has left a boat or turbine blade it will remain in the sea for a very long time. Build up of throw away consumer products can already be observed on beaches and select locations in the ocean.
Remnants of polymer coatings may be much smaller than plastic bottles once leaving a turbine blade, but there is a risk that it will be consumed by small organisms. Eventually, due to bioaccumulation, toxins from polymers enter the food chain. Recently, a chemical called Bisphenol A (BPA) has been removed from consumer products due to health concerns. In this case BPA acts as an endocrine disruptor. Since organisms such as barnacles live off the bottom of boats, it can be assumed that they too are interacting with these chemicals. These chemicals should not be breathed in by the person applying epoxy coatings.
For a brief news article about BPA please see the following:
http://news.mongabay.com/2010/0328-hance_bpa_oceans.html
In addition to new polymers being used there has also been move to adding additional components to these epoxies in order to improve performance. For instance, Silicon Dioxide, typically known as glass is added to improve strength, a nanotechnology product is using carbon nano tubes and a velvet-like product is using nylon microfibers to mimic the hair on a seal. From a health and safety stance these additives should not be breathed in during mixing of the resins. Otherwise these additives are relatively harmless product to the applicator.
