Marine Biofouling of Polymers - Polymers in a Marine Environment - page 43

2.5.1 Historical Methods - Anti-fouling Paint
Many traditional anti-fouling systems are paints. Copper oxide, arsenic, and mercury
oxide are some of the popular anti-foulants. Solvents such as turpentine oil, naphtha,
and benzene are also used as anti-foulants. Linseed oil, shellac varnish, tar, and a
range of resins are used as binders [2].
TBT oxide and TBT luoride are organotin compounds and are powerful fungicides
that completely inhibit the growth of fouling microorganisms. The paints containing
these compounds are classiied as insoluble and soluble matrices, depending on the
binder characteristics and degree of water solubility [62]. They are easily handled
and compatible with many other biologically active compounds [2]. The use of these
organotins is now banned because they have a toxic effect on marine lora and fauna
which includes severe deformities in sea animals and bioaccumulation of tin in some
ducks, seals and ish [63].
2.5.1.1 Insoluble Matrix
These paints ( Figure 2.14b ) are insoluble and do not erode after immersion in water
[2]. Examples of these include: vinyl, epoxy, acrylic or chlorinated rubber polymers.
When these polymer coatings are immersed in seawater, they get dissolved and
penetrate deep into the ilms and release more poisonous material in to the water.
The advantage of these types of paint is that they are mechanically strong, not
susceptible to cracking and stable to oxidation and photo-degradation [64]. They are
released in bursts and so have a short life span of only 12−18 months. During this
short burst the compounds can also affect the environment [2, 64].
2.5.1.2 Soluble Matrix
In order to improve the anti-fouling eficiency with time, soluble matrix paints
( Figure 2.14a ), were developed by incorporating binding materials [2]. The leached
layer is thinner and the toxic materials deep inside the ilm are easily exposed to water,
which increases their lifespan [62]. Rosin is found in a high proportion in these ilm
forming materials [2].