Coating composition for substrates immersed in water

Abstract

The invention relates to a coating composition comprising a) seawater-hydrolyzable groups covalently linked to a polymer backbone, which seawater-hydrolyzable groups are capable of undergoing hydrolysis or ion-exchange when exposed to sea-water, rendering the polymer partially soluble or dispersible in seawater, and b) zwitterionic groups covalently linked to a polymer backbone wherein the polymer backbones to which the sea-water-hydrolyzable groups and the zwitterionic groups are attached serve as a film-forming binder in the coating composition, and wherein the molar ratio of the seawater-hydrolyzable groups a) to the zwitterionic groups b) is 0.1 or higher. The invention also relates to a method of providing a substrate with anti-fouling performance and to a coated substrate.

Claims

1. A coating composition comprising a) seawater-hydrolyzable groups covalently linked to an acrylic polymer, which seawater-hydrolyzable groups are capable of undergoing hydrolysis or ion-exchange when exposed to seawater, rendering the polymer partially soluble or dispersible in seawater, and b) zwitterionic groups covalently linked to the acrylic polymer wherein the molar ratio of the seawater-hydrolyzable groups a) to the zwitterionic groups b) is 0.1 or higher, wherein the seawater hydrolyzable groups are selected from the group consisting of non-metal salt groups, metal salt groups, silyl ester groups, and mixtures thereof, and wherein the non-metal salt groups covalently linked to the acrylic polymer are selected from the group consisting of quaternary and acid salts of dialkylaminoalkyl(meth)acrylates, quaternary and acid salts of dialkylaminoalkyl(meth)acrylamides, N,N-diallyldialkyl ammonium halide, (3-methacryloylamido)propyl trimethylammonium halide salt; (3-acryloylamido)propyl trimethylammonium halide salt; (3-methacryloylamido)propyl trimethylammonium sulfonate salt, (3-acryloylamido)propyl trimethylammonium sulfonate salt, (3-methacryloyl)propyl trimethylammonium sulfonate salt, (3-acryloyl)propyl trimethylammonium sulfonate salt, and amine and phosphine salts of polymerizable unsaturated carboxylic and sulphonic acids wherein the silyl ester groups covalently linked to the acrylic polymer are selected from the group consisting of triisopropylsilyl (meth)acrylate, triisobutylsilyl (meth)acrylate, triphenylsilyl (meth)acrylate, and t-butyldiphenylsilyl (meth)acrylate.

2. The coating composition according to claim 1, wherein the molar ratio of the seawater-hydrolyzable groups a) to the zwitterionic groups b) is 0.5 or higher.

3. The coating composition according to claim 1, wherein the molar ratio of the seawater-hydrolyzable groups a) to the zwitterionic groups b) is 50.0 or lower.

4. The coating composition according to claim 1, wherein the seawater-hydrolyzable groups a) and the zwitterionic groups b) are covalently linked to the same polymer backbone.

5. The coating composition according to claim 1, wherein the seawater-hydrolyzable groups a) and the zwitterionic groups b) are covalently linked to different polymer backbones.

6. The coating composition according to claim 1, wherein the coating composition further comprise an ingredient having marine biocidal properties.

7. The coating composition according to claim 1, wherein the coating composition is a liquid coating composition comprising a volatile organic solvent.

8. A method of providing a substrate with anti-fouling performance in an aqueous environment comprising a) applying the coating composition according to claim 1 to the substrate, b) allowing the coating composition to cure to form a coating layer, and c) locating the coated substrate in an aqueous environment.

9. A substrate having a surface to be at least partly immersed in water, wherein the surface to be immersed in water is coated with a coating composition according to claim 1.

10. The substrate according to claim 9, wherein the substrate is selected from ship hulls, boat hulls, buoys, drilling platforms, oil or gas production or storage rigs, pipes, and fish farms.

Description

EXAMPLE 1

(1) Preparation of a Polymer Having Zwitterionic Groups and Sea-Water Hydrolyzable Groups Covalently Linked to the Polymer Backbone

(2) To a polymerisation reaction vessel containing Xylene:Butanol at 85 C. [143.7 g Xylene: 143.7 g Butanol] was added dropwise, with mechanical stirring, two monomer feed solutions.

(3) Feed solution 1: A solution of monomers consisting of, MATMA-DBSA (solid) (474.47 g, of solution @ 52.69% solids in 1:1 Xylene Butanol), 0.49 moles, Ralumer SPE 41.28 g, 0.16 moles.

(4) Feed solution 2: Butylmethacrylate (BMA) 371.19 g, 2.61 moles, and 2,2-azodi(2-methylbutyronitrile) (AMBN) initiator 12.55 g, 0.06 moles in 112.95 g (1:1 Xylene:Butanol, 10 wt %).

(5) Both monomer feeds were added simultaneously using a Watson-Marlow peristaltic pump at a rate such that the addition took 5 h. Once the addition of the feed was complete the temperature was increased to 95 degrees C., the AMBN (boost) (6.27 g, 0.03 moles) was added (in 56.43 g Xylene:Butanol (1:1)) and the reaction was held for 2 h. The cooled viscous polymer solution, was placed in a storage vessel.

(6) The molar ratio of sea-water-hydrolyzable groups to zwitterionic groups is 3.0.

EXAMPLE A

(7) Preparation of a Polymer with Sea-Water Hydrolyzable Groups Covalently Linked to the Polymer Backbone, but No Zwitterionic Groups

(8) To a polymerisation reaction vessel containing Xylene:Butanol at 85 degrees C. [123.72 g Xylene: 123.72 g Butanol] was added dropwise, with mechanical stirring, a solution of monomers consisting of, MATMA-DBSA (solid) (474.47 g, of solution@52.69% solids in 1:1 Xylene Butanol), 0.49 moles, BMA 278.39 g, 1.96 moles, and AMBN initiator 4.71 g, 0.02 moles in 42.39 g (1:1 Xylene:Butanol, 10 wt %).

(9) The monomer feed was added using a Watson-Marlow peristaltic pump at a rate such that the addition took 5 h. Once the addition of the feed was complete the temperature was increased to 95 degrees C., the AMBN (boost) (2.35 g, 0.01 moles) was added (in 21.15 g Xylene:Butanol (1:1)) and the reaction was held for 2 h. The cooled viscous, was placed in a storage vessel.

EXAMPLE 2

According to the Invention

(10) Preparation of a Marine Antifouling Coating Composition According to the Invention Comprising the Polymer Prepared in Example 1.

(11) The antifouling coating composition was prepared by mixing the materials listed in Table 1 in the stated amounts by weight using a high speed disperser to form a fouling-control paint.

(12) TABLE-US-00001 TABLE 1 Name Description Wt % Polymer solution of Example 1 Binder 11.5 Chlorinated paraffin (Cereclor Plasticiser 5 48, Ineos Chlor) Copper pyrithione (Lonza) Biocide 4 Iron Oxide (Bayferrox 130BM) Pigment 7 Zinc Oxide (Larvik) Pigment 12 Copper Oxide (American Chemet) Biocide 40 Polyamide wax (Disparlon Thixotrope 2 (A600-020X, Kusomoto Chemicals)) Xylene Solvent 7

EXAMPLE B

Comparative

(13) Comparative Antifouling Coating Composition Comprising the Polymer Prepared in Example A.

(14) The antifouling coating composition was prepared by mixing the materials listed in Table 2 in the stated amounts by weight using a high speed disperser to form a fouling-control paint.

(15) TABLE-US-00002 TABLE 2 Name Description Wt % Polymer solution of Example A Binder 11.5 Chlorinated paraffin (Cereclor Plasticiser 5 48, Ineos Chlor) Copper pyrithione (Lonza) Biocide 4 Iron Oxide (Bayferrox 130BM) Pigment 7 Zinc Oxide (Larvik) Pigment 12 Copper Oxide (American Chemet) Biocide 40 Polyamide wax (Disparlon Thixotrope 2 (A600-020X, Kusomoto Chemicals)) Xylene Solvent 7

(16) Antifouling Testing

(17) As a test of antifouling performance the paints of Examples 2 and B were each applied to plywood boards which had been pre-painted with a commercial anticorrosive primer and the boards were immersed in the sea in Singapore. The paint films were periodically assessed for settlement of marine fouling organisms and the results are shown in Table 3 below.

(18) In all results quoted below, 0%=Totally clean, 100%=Totally fouled.

(19) TABLE-US-00003 TABLE 3 Total % coverage of fouling Immersion time Example 2 Comparative Example B 50 weeks 23.0% 44.2%

(20) The test results show that a coating composition comprising the polymer according to the invention (Example 2) had substantially better antifouling performance compared to a coating composition comprising the comparison polymer of Example A (Example B).