Fouling control coating compositions
The present application discloses a fouling control coating composition comprising a polysiloxane-based binder system, 0.01-20% by dry weight of one or more hydrophilic-modified polysiloxanes, and one or more biocides. The hydrophilic-modified polysiloxane may be a poly(oxyalkylene)-modified polysiloxane, e.g. a polysiloxane having grafted thereto poly(oxyalkylene) chains and/or having incorporated in the backbone thereof poly(oxyalkylene) chains. The poly(oxyalkylene) may e.g. be selected from polyoxyethylene, polyoxypropylene and poly(oxyethylene-co-oxypropylene) (polyethylene glycols/polypropylene glycols). The application further discloses a marine structure comprising on at least a part of the outer surface thereof an outermost coating prepared from the coating composition. Moreover, the application discloses the use of the combination of non-reactive hydrophilic-modified polysiloxanes and biocides, wherein the weight ratio between the hydrophilic-modified polysiloxanes and the biocides is in the range 1:0.2 to 1:6, for improving the antifouling properties of a polysiloxane based coating composition.
1. A fouling control coating composition comprising:
A) 50-90% by dry weight of the coating composition of a polysiloxane-based binder system consisting of (i) a binder and optionally (ii) a cross-linking agent,
wherein the binder (i) constitutes 20-90% by dry weight of the coating composition, and is a curable diorganopolysiloxane represented by general formula (1):
wherein:
each A 1 is independently selected from the group consisting of a hydroxyl group and a hydrolysable group;
each A 2 is independently selected from the group consisting of an alkyl, aryl, alkenyl and a hydrolysable group;
each A 3 and A 4 is independently selected from the group consisting of alkyl, aryl, and alkenyl; and
a=1-25,000, b=1-2,500 and a+b is at least 30;
wherein the cross-linking agent, if present, constitutes 0-10% by dry weight of the coating composition;
B) 0 to 35% by dry weight of the coating composition of pigments and/or fillers;
C) 0.01-20% by dry weight of one or more hydrophilic-modified polysiloxanes, wherein the hydrophilic-modified polysiloxanes are selected from poly(oxyalkylene)-modified polysiloxanes, wherein the poly(oxyalkylene) is selected from the group consisting of polyoxyethylene, polyoxypropylene and poly(oxyethylene-co-oxypropylene), and
D) one or more biocides, wherein said one or more biocides are selected from the group consisting of an organic biocide and cuprous oxide;
wherein the weight ratio between the one or more hydrophilic-modified polysiloxanes and the one or more biocides is in the range 1:0.2 to 1:6, and
wherein the one or more hydrophilic-modified polysiloxanes do not contain groups that can react with the binder or any cross-linker.
2. The coating composition according to claim 1 , wherein the one or more hydrophilic-modified polysiloxanes constitute 0.05-10% by dry weight of the coating composition.
3. The coating composition according to claim 2 , wherein the one or more hydrophilic-modified polysiloxanes constitute 2-7% by dry weight of the coating composition.
4. The coating composition according to claim 1 , wherein the one or more biocides constitutes 0.1-10% by dry weight of the coating composition.
5. The coating composition according to claim 1 , wherein the one or more biocides are selected from the group consisting of 3-(3,4-dichlorophenyl)-1,1-dimethylurea, N 2 -tert-butyl-N 4 -cyclopropyl-6-methylthio-1,3,5-triazine-2,4-diamine, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, bis(1-hydroxy-2(1H)-pyridinethionato-O,S)-(T-4) zinc, bis(1-hydroxy-2(1H)-pyridinethionato-O,S)-T-4) copper, zinc ethylene-1,2-bis-dithiocarbamate and cuprous oxide.
6. The coating composition according to claim 1 , wherein the one or more biocides are selected from the group consisting of zinc pyrithione, copper pyrithione, and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one and cuprous oxide.
7. The coating composition according to claim 1 , wherein at least one biocide is a pyrithione complex or cuprous oxide.
8. The coating composition according to claim 1 , wherein one or more biocides is a pyrithione complex and cuprous oxide.
9. The coating composition according to claim 1 , wherein the hydrophilic groups of the one or more hydrophilic-modified polysiloxanes have a number average molecular weight (M n ) in the range of 400-10,000 g/mol.
10. The coating composition according to claim 1 , wherein the hydrophilic-modified polysiloxane has a number average molecular weight (M n ) in the range of 500-50,000 g/mol.
11. The coating composition according to claim 1 ,
wherein the hydrophilic-modified polysiloxanes constitute 0.05-10% by dry weight of the coating composition,
one or more biocides constitutes 0.1-10% by dry weight of the coating composition,
said coating composition having a viscosity in the range of 200-4,000 mPa·s measured at 25° C. in accordance with ISO 2555:1989, and
said coating composition further comprises pigments and/or fillers in an amount of 0-35% by dry weight of the coating composition.
12. The coating composition according to claim 11 , wherein at least one biocide is a pyrithione complex.
13. The coating composition according to claim 1 , wherein at least one biocide is a pyrithione complex.
14. The coating composition according to claim 1 , wherein said hydrolysable groups in said curable diorganopolysiloxane of general formula (1) are selected from alkoxy groups and ketoxime groups.
15. The coating composition according to claim 1 , which comprises:
40-70% by wet weight of the total coating composition of a silanol-terminated polydiorganosiloxane and a cross-linker;
0.1-10% by wet weight of the total coating composition of said one or more biocides; and
0.1-10% by wet weight of the total coating composition of said one or more hydrophilic-modified polysiloxanes selected from poly(oxyalkylene)-modified polysiloxanes.
16. The coating composition according to claim 1 , wherein the cross-linking agent is selected from tetraethoxysilane; vinyltris(methylethyloximo)silane; methyltris(methylethyloximo)silane; vinyltrimethoxysilane; methyltrimethoxysilane; vinyltriisopropenoxysilane; and hydrolysis-condensation products of the same.
17. A marine structure comprising on at least a part of the outer surface thereof an outermost coating prepared from a coating composition as defined in claim 1 .
18. The structure according to claim 17 , wherein at least as part of the outer surface carrying the outermost coating is a submerged part of said structure.
19. The structure according to claim 17 , wherein the one or more biocides of the coating composition are selected from the group consisting of 3-(3,4-dichlorophenyl)-1,1-dimethylurea, N 2 -tert-butyl-N 4 -cyclopropyl-6-methylthio-1,3,5-triazine-2,4-diamine, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, bis(1-hydroxy-2(1H)-pyridinethionato-O,S)-(T-4) zinc, bis(1-hydroxy-2(1H)-pyridinethionato-O,S)-T-4) copper, zinc ethylene-1,2-bis-dithiocarbamate and cuprous oxide.
20. The structure according to claim 17 , wherein the one or more biocides of the coating composition are selected from the group consisting of zinc pyrithione, copper pyrithione, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one and cuprous oxide.
21. The structure according to claim 17 , wherein at least one biocide of the coating composition is a cuprous oxide.
22. The structure according to claim 17 , wherein one or more biocides of the coating composition is a pyrithione complex and cuprous oxide.
23. The structure according to claim 17 , wherein at least one biocide of the coating composition is a pyrithione complex.