Antifouling coating composition and its use on man-made structures

Abstract

The invention pertains to an antifouling coating composition comprising a copper acrylate polymer, 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethyl pyrrole (tralopyril), and solvent, with the coating composition being substantially free of further biocidal compounds, wherein the copper acrylate polymer is present in an amount of 60-99 wt. % and the tralopyril is present in an amount of 0.1-30 wt. %, the weight percentages for copper acrylate polymer and tralopyril being calculated on the dry weight of the coating composition. In one embodiment, the coating composition comprises 30-70 wt % of solvent, the weight percentage of solvent being calculated on the wet weight of the coating composition. It has been found that the coating composition according to the invention combines a good antifouling performance against both weed and shell fouling, for at least 12 months, i.e. a yacht season, with a high gloss finish, and, when a suitable application method is used, a smooth and level surface.

Claims

1. An antifouling coating composition comprising a copper acrylate polymer, 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethyl pyrrole (tralopyril), and solvent, with the coating composition being substantially free of further biocidal compounds, wherein the copper acrylate polymer is present in an amount of 60-99 wt. % and the tralopyril is present in an amount of 0.1-30 wt. %, the weight percentages for copper acrylate polymer and tralopyril being calculated on the dry weight of the coating composition.

2. The antifouling coating composition according to claim 1 comprising 30-80 wt % of solvent, the weight percentage of solvent being calculated on the wet weight of the coating composition.

3. The antifouling coating composition according to claim 1, wherein the amount of tralopyril is at least 0.5 wt. % and/or at most 20 wt. % the weight percentages for tralopyril being calculated on the dry weight of the coating composition.

4. The antifouling coating composition according to claim 1, wherein the coating composition comprises at least 70 wt. % of copper acrylate polymer and/or at most 98 wt. % the weight percentages for copper acrylate polymer being calculated on the dry weight of the coating composition.

5. The antifouling coating composition according to claim 1, wherein the coating composition comprises at least 40 wt. % of solvent and at most 75 wt. %, the weight percentage of solvent being calculated on the wet weight of the coating composition.

6. The antifouling coating composition according to claim 1, wherein the composition comprises 0-15 wt. % of further components, wherein further components are all compounds which are not solvent, copper acrylate polymer, and tralopyril, the weight percentages of further components being calculated on the wet weight of the coating composition.

7. The antifouling coating composition according to claim 1, wherein the coating composition has a pigment volume concentration (PVC) of less than 30%.

8. The antifouling coating composition according to claim 1 wherein the copper acrylate polymer has an acrylic backbone bearing at least one terminal group of the formula: ##STR00007## wherein X represents ##STR00008## M is copper; n is an integer of 1 to 2; R represents an organic residue selected from ##STR00009## and R1 is a monovalent organic residue.

9. The antifouling coating composition according to claim 8 wherein X represents ##STR00010## and R represents ##STR00011## wherein R1 is a monovalent organic residue.

10. A process for protecting a man-made structure immersed in a fouling aquatic environment wherein the structure is coated with an antifouling coating composition according to claim 1.

11. The process according to claim 10, wherein the coating composition is applied through spraying.

12. A man-made structure immersed in a fouling aquatic environment coated with an antifouling coating composition according to claim 1.

13. The man-made structure according to claim 12 that is a ship or boat hull.

14. The man-made structure according to claim 12, wherein the antifouling coating has a thickness after curing of 75 to 150 microns.

15. The antifouling coating composition according to claim 1, wherein the coating composition comprises at least 55 wt. % and at most 65 wt. % of solvent, the weight percentage of solvent being calculated on the wet weight of the coating composition.

16. The antifouling coating composition according to claim 1, wherein the composition comprises 0-5 wt. % of further components, wherein further components are all compounds which are not solvent, copper acrylate polymer, and tralopyril, the weight percentages of further components being calculated on the wet weight of the coating composition.

17. The antifouling coating composition according to claim 1, wherein the coating composition has a pigment volume concentration (PVC) of less than 5%.

18. The man-made structure according to claim 13 that is a ship or boat hull of fiberglass or plastic.

19. The man-made structure according to claim 14, wherein the antifouling coating has a thickness after curing of 90-120 microns.

Description

EXAMPLES

(1) In the examples, tralopyril is provided as biocide, provided under the trade name Econea.

(2) The copper acrylate resin has the following properties: It has an acrylic backbone bearing at least one terminal group of the formula I above, wherein X is

(3) ##STR00006##
M is copper, n is 1, and R is a residue derived from naphthenic acid. The residue has an acid value of 200 mg KOH/gram. The resin has an acid value of 66-72 mg KOH/gram.

(4) In the following, the composition of the coating is provided as weight %, calculated on the wet coating composition. The pigment volume concentration (PVC) is in volume % on the dry volume of the coating.

(5) The indication further ingredients stands for thixotropes and color pigments, and in some cases co-binders such as hydrocarbon resin and/or rosin. Comparable compositions where used in coating compositions which are compared.

Example 1

(6) This example shows the effect of the composition according to the invention, comprising only tralopyril as biocide in comparison with a composition comprising CuSCN and N-tert-butyl-N-cyclopropyl-6-(methylthio)-1,3,5-triazine-2,4-diamine (Irgarol 1051).

(7) Coating compositions were prepared by high-speed mixing of the constituents mentioned in table 1a.

(8) TABLE-US-00001 TABLE 1a Composition 1 according to the Comparative invention composition A Biocide 7.8 wt. % Econea 22.3 wt. % CuSCN and 2.2 wt. % Irgarol 1051 Copper acrylate polymer 31.8 wt. % 27.6 wt. % Solvent 58.2 wt. % 44.4 wt. % Other components 2.2 wt. % 3.5 wt. % PIGMENT VOLUME 14.6% 28.6% CONCENTRATION

(9) Panels were roller-coated with the coating composition and kept for 12 months in seawater attached to a raft located in West Palm Beach, Fla. After 12 months, the fouling coverage of the panel was determined. Table 1 b gives the percentages of the panel which were, respectively clean, covered with slime, covered with weed, and covered with shells.

(10) TABLE-US-00002 TABLE 1b Composition 1 according to the Comparative invention composition A % clean 99% 10% % slime 0 0 % weed 0 0 % shell 1% 90%

(11) As can be seen from Table 1 b, both compositions showed no fouling by slime and weed. However, the comparative composition suffered severely from fouling by shells, while the composition according to the invention was almost completely clean.

Example 2

(12) This example shows the effect of the presence of tralopyril in a copper acrylate coating composition, in comparison with a composition not containing tralopyril.

(13) Coating compositions were prepared by high-speed mixing of the constituents mentioned in table 2a.

(14) TABLE-US-00003 TABLE 2a Composition 2 according to the Comparative invention composition B Biocide 1.0 wt. % Econea 0 Copper acrylate polymer 31.0 wt. % 31.4 wt. % Solvent 56.7 wt. % 57.3 wt. % Other components 11.3 wt. % 11.3 wt. % PIGMENT VOLUME 3.8% 2.2% CONCENTRATION

(15) Panels were roller-coated with the coating composition and kept for 10 months in seawater at Burnham, United Kingdom. After 10 months, the fouling coverage of the panel was determined. Table 2b gives the percentages of the panel which were, respectively clean, covered with slime, covered with weed, and covered with shells.

(16) TABLE-US-00004 TABLE 2b Composition 2 according to the Comparative invention composition B % clean 20% 5% % slime 80% 0 % weed 0 10% % shell 0 85%

(17) As can be seen from Table 2b, the composition according to the invention showed a 20% clean surface. The comparative composition suffered severely from fouling by shells, and additionally by some fouling by weed, and showed less clean surface than the composition according to the invention. It should also be noted that the composition according to the invention is effective at very low Pigment Volume Concentrations.

Example 3

(18) This example compares a composition of the invention with a composition which additionally comprises zinc pyrithione.

(19) Coating compositions were prepared by high-speed mixing of the constituents mentioned in table 3a.

(20) TABLE-US-00005 TABLE 3a Composition 3 according to the Comparative invention composition C Biocide 4.0 wt. % Econea 2.0 wt. % Econea and 2.0 wt. % Zinc pyrithione Copper acrylate polymer 17 wt. % 17 wt. % Solvent 55 wt. % 55 wt. % Other ingredients 24 wt. % 24 wt. % PIGMENT VOLUME 7.72% 7.72% CONCENTRATION

(21) Panels were roller-coated with the coating composition and kept for 8 months in seawater attached to a raft located in Brazilian waters. After 8 months, the fouling coverage of the panel was determined. Table 3b gives the percentages of the panel which were, respectively clean, covered with slime, covered with weed, and covered with shells.

(22) TABLE-US-00006 TABLE 3b Composition 3 according to the Comparative invention composition C % clean 20% n.d. % slime 80% 10% % weed 0 n.d. % shell 10% 60% n.d. stands for not determined. It appeared that the comparative coating C had worn off on one-third of the panel following 8 months of immersion, making a meaningful determination of the percentages clean, slime, and weed not possible.

(23) As can be seen from Table 3b, the composition according to the invention showed 20% clean surface, was completely free of weed and showed a lot less shell (only 10%) than comparative composition C. Further, the coating was intact and not showing any evidence of polish through. The comparative composition however polished away too fast, which makes it unsuitable for commercial use.

Example 4

(24) Further to Example 3 above, this example investigates the effect of zinc pyrithione on the lifetime of the antifouling coating.

(25) Coating compositions were prepared by high-speed mixing of the constituents mentioned in table 4a.

(26) TABLE-US-00007 TABLE 4a Composition 4 according to the Comparative invention composition D Biocide 6.0 wt. % Econea 6.0 wt. % zinc pyrithione Copper acrylate polymer 36.9 wt. % 36.9 wt. % Solvent 53.0 wt. % 53.0 wt. % Other ingredients 4.1 wt. % 4.1 wt. % PIGMENT VOLUME 9.9% 9.5% CONCENTRATION

(27) Panels were roller-coated with the coating composition and kept for 13 months in seawater at Newton Ferrers, United Kingdom. After 13 months, it appeared that on the panel according to the invention 100% of the coating was still present. In contrast, on the panel provided with the comparative coating composition only 15% of the coating remained. Apparently, the use of zinc pyrithione detrimentally affects the properties of the antifouling coating.

Example 5

(28) This example compares a composition of the invention with a composition which comprises a silyl acrylate resin rather than a copper acrylate resin.

(29) Coating compositions were prepared by high-speed mixing of the constituents mentioned in table 5a.

(30) TABLE-US-00008 TABLE 5a Composition 5 according to the Comparative invention composition E Biocide 4.0 wt. % Econea 3.0 wt. % Econea Copper acrylate polymer 36.1 wt. % 0 Silyl acrylate polymer.sup.1 0 47.3 wt. % Solvent 58.2 wt. % 48.4 wt. % Other ingredients 1.7 wt. % 0.3 wt. % PIGMENT VOLUME 7.0% 3.8% CONCENTRATION .sup.1The silyl acylate polymer is Polyace NSP-100 commercially available from Nitto Kasei.

(31) Panels were roller-coated with the coating composition and kept for 8 months in seawater at Newton Ferrers, United Kingdom. After 8 months, the fouling coverage of the panel was determined. Table 5b gives the percentages of the panel which were, respectively clean, covered with slime, covered with weed, and covered with shells.

(32) TABLE-US-00009 TABLE 5b Composition 5 according to the Comparative invention composition E % clean 100% 0 % slime 0 70% % weed 0 20% % shell 0 10%

(33) As can be seen from Table 5b, the composition according to the invention showed 100% clean surface. In contrast, the comparative composition comprising silyl acrylate rather than copper acrylate shows heavy fouling and 0% clean surface.

Example 6

(34) This example compares a composition of the invention with a composition which comprises a zinc acrylate resin rather than a copper acrylate resin.

(35) Coating compositions were prepared by high-speed mixing of the constituents mentioned in table 6a.

(36) TABLE-US-00010 TABLE 6a Composition 6 according to the Comparative invention composition F Biocide 4.0 wt. % Econea 4.0 wt. % Econea Copper acrylate polymer 36.1 wt. % 0 Zinc acrylate polymer.sup.1 0 47.3 wt. % Solvent 58.2 wt. % 47.9 wt. % Other ingredients 1.7 wt. % 0.8 wt. % PIGMENT VOLUME 7.0% 5.4% CONCENTRATION .sup.1The zinc acylate polymer is RC4343 commercially available from International paint.

(37) Panels were roller-coated with the coating composition and kept for 8 months in seawater at Newton Ferrers, United Kingdom. After 8 months, the fouling coverage of the panel was determined. Table 6b gives the percentages of the panel which were, respectively clean, covered with slime, covered with weed, and covered with shells.

(38) TABLE-US-00011 TABLE 6b Composition 6 according to the Comparative invention composition F % clean 80% 0 % slime 20% 0 % weed 0 50% % shell 0 50%

(39) As can be seen from Table 6b, the composition according to the invention showed 80% clean surface. In contrast, the comparative composition comprising zinc acrylate rather than copper acrylate shows 0% clean surface.

Example 7

(40) This example compares a composition of the invention with a composition which comprises 4,5-dichloro-2-n-octyl-4-isothizolin-3-one (SeaNine 211) as biocide instead of tralopyril.

(41) Coating compositions were prepared by high-speed mixing of the constituents mentioned in table 7a.

(42) TABLE-US-00012 TABLE 7a Composition 7 according to the Comparative invention composition G Biocide 5.2 wt. % Econea 5.8 wt. % SeaNine 211 Copper acrylate polymer 27.6 wt. % 27.6 wt. % Solvent 65.3 wt. % 65.4 wt. % Other ingredients 1.9 wt. % 1.3 wt. % PIGMENT VOLUME 12.1% 16.0% CONCENTRATION

(43) Panels were roller-coated with the coating composition and kept for 12 months in seawater at Oyster Bay, N.Y. After 12 months, the fouling coverage of the panel was determined. Table 7b gives the percentages of the panel which were, respectively clean, covered with slime, covered with weed, and covered with shells.

(44) TABLE-US-00013 TABLE 7b Composition 7 according to the Comparative invention composition G % clean 50% 0 % slime 40% 0 % weed 10% 30% % shell 0 70%

(45) As can be seen from Table 7b, the composition according to the invention showed 50% clean surface. In contrast, the comparative composition comprising SeaNine 211 rather than tralopyril shows 0% clean surface.