What is marine fouling?
The growth of shell, barnacles, tubeworms, seaweed and microorganisms on sea water immersed surfaces like ship hulls.
Fouling produce roughness,reduce speed and increase turbulent flow, acoustic noise,drag and fuel consumption.
10 microns increasein hull roughness can result in 1 % increase in fuel consumption!
Vessel activityType, severity and extent of marine fouling depend on vessel trading pattern,speed, activity and geographic location.
History
The early Phoenicians nailed copper strips to their ship’s hulls to prevent fouling.Admiral Nelson made use of copperplating on the hulls and his war ships were far more maneuverable than those used by the French (1805), a tactical advantage he used to obtain a victorious outcome.
Antifoulant biocides have included DDT, phenyl-mercury, pentachlorophenol, organolead, arsenic compounds and copper mixed into binders of gum rosin, chlorinated rubber, vinyls, acrylate.
Tributyltin TBT
High microbiological and fungicidial activity makes TBT derivates effective biocides and very toxic to a wide range of marine organisms.
Used since the early 1970’s in antifouling paints. Estimated over 70% of the world’socean going fleet were painted with TBT self- polishing based paints. Superior fouling prevention and fuel savings.
Self-polishing SPC antifouling paint
TBT biocide chemically bonded in acopolymer paint, allowing thick paintfilms with controlled, uniform releaseof the biocide to the surface. Effectiveprevention of fouling and reduction offrictional drag.
92% of TBT SPC-painted ships show low fouling with life-time of 5 years +
Regulations
Research has indicated that TBT may beresponsible for the weakening of oyster and mussel shells as well as slowing the growth of various species of aquatic snails (imposex).
These concerns have led to regulatorymeasures around the world resulting ina Ban on TBT
Restrictions on the use of TBT based AF
In the US, the 1988 Organotin Antifouling Paint Control Act restricted the use of TBT-based antifoulants to ships larger than 25 mtrs. in length or those with aluminium hulls. This act also restricted the release rate of TBT. Japan unilaterally banned TBT antifouling in the early 1990’s.
In 1990, the International Maritime Organization (IMO) of the United Nations’ Marine Environment Protection Commitee (MEPC) adopted a resolution that recommended governments adopt measures to restrict the use and release rate of TBT-based antifoulants.The MEPC is made up of IMO member countries with shipping interests.
IMO proposal
““A worldwide ban on the A worldwide ban on the applicationapplication of of TBT (tri-butyl tin) antifouling systems on TBT (tri-butyl tin) antifouling systems on ships byships by 11stst January 2003” January 2003”
““A ban on the presence of TBT antifouling A ban on the presence of TBT antifouling systems on ships bysystems on ships by 11stst January 2008” January 2008” AA sealer sealer coat can be used to overcoat coat can be used to overcoat existing TBT-based antifoulingexisting TBT-based antifouling
Urges all parties involved Urges all parties involved to “refrain from to “refrain from the production, sales, marketing and the production, sales, marketing and application of antifouling systems application of antifouling systems containing organotin compounds acting containing organotin compounds acting as biocides from as biocides from 01/01/200301/01/2003””
IMO update
5-year dockings will require tin-free paint for 20035-year dockings will require tin-free paint for 2003 The treaty needs 25% of tonnage and 25 countries to The treaty needs 25% of tonnage and 25 countries to
ratify it. It becomes law 12 months after this.ratify it. It becomes law 12 months after this. EU will try to keep to the deadline of 1/1/2003 for EU EU will try to keep to the deadline of 1/1/2003 for EU
flagged tonnageflagged tonnage USA will make legislation retroactive to 2003USA will make legislation retroactive to 2003 International Chamber of Shipping in London has International Chamber of Shipping in London has
“recommended that ship operators should observe the “recommended that ship operators should observe the recommended prohibition date with effect from 1 recommended prohibition date with effect from 1 January 2003”January 2003”
So plan to use TBT-free paint from January 2003So plan to use TBT-free paint from January 2003
Main antifouling technology
1. 1. Copper based (Copper based (tin-free)tin-free),, Biocide* type Biocide* type11stst generation Self-Polishing - generation Self-Polishing - Hydration Hydration typetype22nd nd generation Self-Polishing - generation Self-Polishing - Hydrolysis Hydrolysis typetype33rdrd generation Self-Polishing - generation Self-Polishing - Hydrolysis Hydrolysis typetype
* * BiocideBiocide – a chemical which is toxic to fouling – a chemical which is toxic to foulingNote: Hydrolysis mechanism is like TBT typeNote: Hydrolysis mechanism is like TBT type
2. Copper-free, tin-free, 2. Copper-free, tin-free, Biocide* typeBiocide* type3. Biocide* Free Type3. Biocide* Free Type
Foul release, Silicone Foul release, Silicone rubber rubber typetypeOthersOthers
Self-PolishingSelf-Polishing
ReleaseRetentionRenewal
Controlled releaseof biocide ions
Ionized layer ofhighly concentratedbiocide
Efficient ionizationof biocide
Keeping biocideactivity
: Biocide Ion
1. 1. HYDRATION type,HYDRATION type, self-polishing self-polishing HydrationHydration – where water physically – where water physically erodes the antifoulingerodes the antifoulingAlso Also called ablative, eroding, controlled called ablative, eroding, controlled depletion and depletion and 11stst generation tin-free generation tin-free
2.2. HYDROLYSIS type,HYDROLYSIS type, self-polishing self-polishingHydrolysisHydrolysis – where water chemically – where water chemically reacts and dissolves the antifoulingreacts and dissolves the antifouling22ndnd and 3 and 3rdrd generation generation tin-free antifouling tin-free antifouling
Mechanisms for self-polishing
Mainstream copper based tin-free technologyMainstream copper based tin-free technology
TechnologTechnologyy
PolishingPolishingMechanisMechanismm
HydrolysHydrolysis actionis action
HydrolysHydrolysis actionis action
Hydration Hydration actionaction
HydratioHydrationn
actionaction
HydrolysHydrolysis actionis action
Polymer Polymer typetype
OrganoOrgano- - Silyl Silyl
Acrylate Acrylate polymerpolymer
Metallic Metallic Acrylate Acrylate polymerpolymer
Gum Gum Rosin - Rosin -
Water/Ion Water/Ion sensitive sensitive polymerpolymer
Gum Gum Rosin - Rosin -
Water/IoWater/Ion n
sensitive sensitive polymerpolymer
Organo-Organo-tin tin
AcrylateAcrylatepolymerpolymer
Chemical Chemical structurestructure
Claimed Claimed Service Service lifelife
5 years5 years Up to 5 Up to 5 yearsyears
3 years3 years 5 years?5 years? 5 years5 years
Quoted Quoted PerformanPerformance level %ce level %
9595 9090 60 to 8060 to 80 ?? 70 to 9870 to 98
Tin-FreeHydrolysis
2nd Generation
Tin-freeAblative
1st Generation
TBT Antifouling
Tin-freeAblative/
Fibrous type
Tin-FreeHydrolysis
3rd Generation
Hydrolysis gives a consistent(linear) polishing rate
-250
-200
-150
-100
-50
0
0 0.5 1 1.5 2 2.5 3
Tested period(year)
Pol
ishe
d fi
lm th
ickn
ess(
m
icro
n)
2nd generation (Green line) and 3rd generation (Blue line) demonstrate the excellent polishing performance just like TBT-AF (Red line) in below chart
The indoor rotor: 15 knots, 25°c, natural sea water
Hydrolysis gives a consistent(linear) leaching rate of biocide
Biocide Release Rate over Time
0
10
20
30
40
50
0 2 4 6
Time/ years
Co
pp
er le
ach
ing
ra
te/µ
g/d
ay/s
qcm
Hydration
Hydrolysis
Critical LeachingRate
TechnologTechnologyy
Polymer Polymer typetype
OrganoOrgano--Silyl Silyl
AcrylateAcrylate
Metallic Metallic Acrylate Acrylate polymerpolymer
Water/Ion Water/Ion sensitive sensitive polymerpolymer
Organo-Organo-tin tin
AcrylateAcrylatepolymerpolymer
Polymer Polymer coated coated panel panel immersed immersed in sea in sea water for water for 12 12 monthsmonths
% Water % Water AbsorptioAbsorptionn
1-2%1-2% 5-8%5-8% 10-20%10-20% 1-2%1-2%
PerformaPerformancence
95%95% 90%90% 85%85% 95%95%
Service Service LifeLife
5 years5 years 3-5 3-5 yearsyears
2½-3 2½-3 yrsyrs
5 years5 years
TBT Antifouling
Tin-Free Hydrolysis3rd Generation
Tin-FreeHydration1st Generation
Tin-Free Hydrolysis2nd Generation
Lower Absorbance of Water in the Resin means higher Lower Absorbance of Water in the Resin means higher performance - the reaction is controlled at the surfaceperformance - the reaction is controlled at the surface
HYDROLYSIS HYDROLYSIS AntifoulingAntifouling 33rdrd Generation Generation tin-free – Organo-Silyl Acrylate tin-free – Organo-Silyl Acrylate
22ndnd Generation Generation tin-free – Metallic Acrylate tin-free – Metallic Acrylate
HYDRATION AntifoulingHYDRATION Antifouling 11stst Generation Generation - Eroding, ablative, gum rosin, - Eroding, ablative, gum rosin, controlled depletioncontrolled depletion
95%=TBT
90%
70 - 85%
Performance
Performance of Antifouling Paints Performance of Antifouling Paints (%age of ships free from fouling)(%age of ships free from fouling)
The performance of an antifouling is deepen-The performance of an antifouling is deepen-dent on long term, consistent control of the dent on long term, consistent control of the polishing mechanism.polishing mechanism.This is best achieved with the hydrolysis This is best achieved with the hydrolysis mechanism.mechanism.33rdrd generation>2 generation>2ndnd generation>1 generation>1stst generation generationCosts per m²:Costs per m²:
44 :: 2½ 2½ :: 1 1
Summary - Antifouling PerformanceSummary - Antifouling Performance
Foul Release CoatingsFoul Release Coatings
BenefitsBenefits Environmentally Environmentally
friendlyfriendly 5-years between 5-years between
dockingsdockings Smooth surface and Smooth surface and
potential fuel savingspotential fuel savings Easily re-coatedEasily re-coated Self-cleaning or for Self-cleaning or for
slow vessels, easily slow vessels, easily cleanedcleaned
DisadvantagesDisadvantages High cost High cost Masking-off of Masking-off of
topsidestopsides Careful application is Careful application is
required for siliconesrequired for silicones Repair requires more Repair requires more
care with preparationcare with preparation
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