Antifouling coating composition comprising at least two salt-containing copolymers

Abstract

The present invention relates to an antifouling coating composition comprising an ingredient having marine biocidal properties, and at least two different copolymers comprising salt groups. The antifouling coating composition has excellent antifouling properties. The present invention also relates to a method of providing a substrate with antifouling performance in an aqueous environment, and the use of the antifouling coating composition for protection of man-made structures immersed in water.

Claims

1. An antifouling coating composition comprising (a) an ingredient having marine biocidal properties, (b) a first copolymer comprising pendant to the polymer backbone, side chains A1, side chains B1 and optionally side chains C1, and (c) a second copolymer comprising pendant to the polymer backbone, side chains A2, side chains C2, and optionally side chains B2, wherein side chains A1 and A2 are same or different and comprise a non-metal salt group, and have the structure: (Y).sub.nR.sup.1Z(.sup.+) R.sup.2() wherein Y is C(O)O, C(O)NH, O; n is 0 or 1; R.sup.1 is a divalent alkylene having 2 or 3 to 12 carbon atoms, Z is a quaternary ammonium group or quaternary phosphonium group and R.sup.2 is an anionic residue of an acid counter-ion having an aliphatic, aromatic, or alkaryl hydrocarbon group; side chains B1 and B2 are same or different and have the structure (Y).sub.nR.sup.3; side chains C1 and C2 are same or different and have the structure (Y).sub.nR.sup.4; Y is C(O)O, C(O)N(R.sup.6), or O; n is 0 or 1; R.sup.6 is H, a monovalent hydrocarbon group, or a bond to R.sup.3 or R.sup.4; R.sup.3 is a hydrocarbon group, optionally substituted with one or more heteroatoms selected from O, N, S, or a halogen group, wherein the total sum of carbon atoms in R.sup.3 and R.sup.6 in each of side chains B1 and B2 is 5 or more; and R.sup.4 is a hydrocarbon group, optionally substituted with one or more heteroatoms selected from O, N, S, or a halogen group wherein the total sum of carbon atoms in R.sup.4 and R.sup.6 in each of side chains C1 and C2 ranges from 1 to 4; and wherein the molar ratio of $\frac{\mathrm{side}\mathrm{chains}B1}{\mathrm{side}\mathrm{chains}B1+\mathrm{side}\mathrm{chains}C1}$ in the first copolymer is great than or equal to 0.50, and the molar ratio of $\frac{\mathrm{side}\mathrm{chains}B2}{\mathrm{side}\mathrm{chains}B2+\mathrm{side}\mathrm{chains}C2}$ in the second copolymer is less than 0.50.

2. The antifouling coating composition of claim 1 wherein R.sup.3 is a linear, branched or cyclic alkyl or aryl group, optionally substituted with one or more heteroatoms selected from O, N, S, or a halogen group, wherein the total sum of carbon atoms in R.sup.3 and R.sup.6 in each of side chains B1 and B2 is 5 or more; and R.sup.4 is a linear, branched or cyclic alkyl group, optionally substituted with one or more heteroatoms selected from O, N, S, or a halogen group wherein the total sum of carbon atoms in R.sup.4 and R.sup.6 in each of side chains C1 and C2 ranges from 1 to 4.

3. The antifouling coating composition according to claim 1 wherein the anionic residue of the acid counter-ion has an aliphatic, aromatic, or alkaryl hydrocarbon group comprising 6 or more carbon atoms.

4. The antifouling coating composition according to claim 1 wherein the counter-ions comprise 6 to 50 carbon atoms.

5. The antifouling coating composition of claim 1 wherein the first copolymer and the second copolymer are poly(meth)acrylate or poly(meth)acrylamide copolymers.

6. The antifouling coating composition of claim 1 wherein the molar ratio of $\frac{\mathrm{side}\mathrm{chains}B1}{\mathrm{side}\mathrm{chains}B1+\mathrm{side}\mathrm{chains}C1}$ is greater than or equal to 0.60, and the molar ratio of $\frac{\mathrm{side}\mathrm{chains}B2}{\mathrm{side}\mathrm{chains}B2+\mathrm{side}\mathrm{chains}C2}$ is less than 0.40.

7. The antifouling coating composition according to claim 1 wherein the mol % of side chains A1: mol % of side chains B1: mol % of side chains C1 in the first copolymer is 5-50: 50-95: 0-45, and the mol % of side chains A2: mol % of side chains B2: mol % of side chains C2 in the second copolymer is 5-50: 0-45: 50-95, wherein mol % in the first copolymer is based on the total sum of side chains A1+B1+C1 and mol % in the second copolymer in based on the total sum of side chains A2+B2+C2.

8. The antifouling coating composition of claim 1 wherein R.sup.3 is a linear, branched or cyclic alkyl or aryl group, optionally substituted with one or more heteroatoms selected from O, N, S, or a halogen group, wherein the total sum of carbon atoms in R.sup.3 and R.sup.6 in each of side chains B1 and B2 ranges between 5 and 40.

9. A method of providing a substrate with antifouling performance in an aqueous environment by (a) providing the antifouling coating composition as defined in claim 1, (b) applying the coating composition to the substrate, (c) allowing the coating composition to cure to form a coating layer, and (d) locating the coated substrate in the aqueous environment.

10. The antifouling coating composition of claim 1 wherein R.sup.3 is a linear, branched or cyclic alkyl or aryl group, optionally substituted with one or more heteroatoms selected from O, N, S, or a halogen group, wherein the total sum of carbon atoms in R.sup.3 and R.sup.6 in each of side chains B1 and B2 ranges between 5 and 25.

11. The method of claim 9, wherein the substrate is the surface of a boat hull, buoy, drilling platform, oil production rig, or a pipe.

Description

EXAMPLES

(1) Preparation of Monomer with Functionality A1 or A2.

(2) Dimethylaminopropyl methacrylamide (192.1 g), dimethylcarbonate (179.6 g) and methanol (208 g), were placed in a stainless steel, high pressure reaction vessel. The sealed vessel was heated to 125 C. for 4 hours. The cooled solution was filtered and dried in vacuo after addition of methanol (150 g).

(3) The resulting viscous amber liquid, trimethylaminopropyl methacrylamide (244.7 g) was diluted with xylene (200 g) and placed in a 2 L round bottom flask. To this was added at room temperature with stirring over 30 minutes a solution of dodecylbenzenesulphonic acid (244.7 g) in xylene (200 g), and stirring was continued overnight to provide a solution of 3-(methacrylamidopropyl) trimethylammonium dodecylbenzenesulfonate (MATMA-DBSA) in xylene.

Example 1A

(4) A solution of monomers consisting of MATMA-DBSA (250.0 g), iBoMA (435.2 g) and 2,2-Azobis-2-methylbutyronitrile (AMBN) initiator (4.7 g) AMBN in xylene (23.5 g) and butanol (23.5 g) was added at constant rate over 5 hours with mechanical stirring to a polymerisation reaction vessel containing xylene (202.1 g) and butanol (202.1 g) held at 85 degrees C. Once the addition was complete the temperature was increased to 95 C., and a solution of AMBN (2.4 g) in xylene (12 g) and butanol (12 g) was added and the reaction was held at this temperature for 2 hours. The reaction mixture was then cooled to provide a solution of the MATMA-DBSA:iBoMA copolymer of Example 1A, which was placed in a storage vessel.

(5) The molar ratio of monomers used to prepare this polymer was 20 mol % of salt monomer: 80 mol % of isobornyl methacrylate. Each monomer molecule incorporated into the copolymer molecule provided one pendant side chain.

Example 1B

(6) A solution of monomers consisting of MATMA-DBSA (250.0 g), BMA (278.4 g) and AMBN initiator (4.7 g) in xylene (23.5 g) and butanol (23.5 g) was added at constant rate over 5 hours with mechanical stirring to a polymerisation reaction vessel containing xylene (123.7 g) and butanol (123.7 g) held at 85 degrees C. Once the addition was complete the temperature was increased to 95 C., a solution of AMBN (2.4 g) in xylene (12 g) and butanol (12 g) was added and the reaction was held at this temperature for 2 hours. The reaction mixture was then cooled to provide a solution of the MATMA-DBSA:BMA copolymer of Example 1B, which was placed in a storage vessel.

(7) The molar ratio of monomers used to prepare this polymer was 20 mol % of salt monomer: 80 mol % of butyl methacrylate. Each monomer molecule incorporated into the copolymer molecule provided one pendant side chain.

Example 1C

(8) A solution of monomers consisting of MATMA-DBSA (250.0 g), iBoMA (217.6 g), BMA (139.2 g) and AMBN initiator (4.7 g) in xylene (23.5 g) and butanol (23.5 g) was added at constant rate over 5 hours with mechanical stirring to a polymerisation reaction vessel containing xylene (162.9 g) and butanol (162.9 g) held at 85 degrees C. Once the addition was complete the temperature was increased to 95 C., and a solution of AMBN (2.4 g) in xylene (12 g) and butanol (12 g) was added and the reaction was held at this temperature for 2 hours. The reaction mixture was then cooled to provide a solution of the MATMA-DBSA:iBoMA:BMA copolymer of Example 1C, which was placed in a storage vessel.

(9) The molar ratio of monomers used to prepare this polymer was 20 mol % of salt monomer: 40 mol % of butyl methacrylate: 40 mol % of isobornyl methacrylate. Each monomer molecule that incorporated into the copolymer molecule provided one pendant side chain.

Example Paint 2a

(10) Example 2a an antifouling coating composition according to the invention comprising two copolymers. The first copolymer is the copolymer of Example 1A. The second copolymer is the copolymer of Example 1B.

(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 Dry Film Name Description volume Wt % Polymer solution of example Binder 20 11.5 1A Polymer solution of example Binder 20 11.5 1B Chlorinated paraffin (Cereclor Plasticiser 13.5 5 48, Ineos Chlor) Copper pyrithione (Lonza) Biocide 8 4 Iron Oxide (Bayferrox 130BM) Pigment 5 7 Zinc Oxide (Larvik) Pigment 8 12 Copper Oxide (American Biocide 24 40 Chemet) Polyamide wax (Disparlon Thixotrope 1.5 2 (A600-020X, Kusomoto Chemicals)) Xylene Solvent 0 7

Example Paint 2b

(13) Example Paint 2b is an antifouling coating composition which is provided as a comparative example. It comprises just one copolymer: the copolymer of Example 1C. The monomers making up the copolymer in Example Paint 2b are exactly the same, and in the same relative proportions, as the monomers making up the two copolymers in Example Paint 2a.

(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.

(15) TABLE-US-00002 TABLE 2 Dry Film Name Description volume Wt % Polymer solution of example Binder 40 23 1C Chlorinated paraffin (Cereclor Plasticiser 13.5 5 48, Ineos Chlor) Copper pyrithione (Lonza) Biocide 8 4 Iron Oxide (Bayferrox 130BM) Pigment 5 7 Zinc Oxide (Larvik) Pigment 8 12 Copper Oxide (American Biocide 24 40 Chemet) Polyamide wax (Disparlon Thixotrope 1.5 2 (A600-020X, Kusomoto Chemicals)) Xylene Solvent 0 7
Antifouling Testing

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

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

(18) TABLE-US-00003 TABLE 3 Total % coverage of fouling Paint Comparative Paint Location Example 2a Example 2b Singapore 14% 63% (12 months immersion) Hartlepool 38% 91% (12 months immersion)

(19) The test results show that a coating composition comprising the two copolymers according to the invention (Paint 2a) had substantially better antifouling performance compared to a coating composition comprising just one copolymer (Paint 2b).

(20) This is surprising because, in both paints, the monomers making up the polymer(s) were exactly the same, and in exactly the same proportions (20 mol % salt: 40 mol % butyl methacrylate: 40 mol % isobornyl methacrylate). The only difference between the paints was how the monomers were distributed between the copolymers. In Paint 2a, the first polymer was made up from half the salt monomers and all the isobornyl methacrylate monomers, and the second polymer was made up from half the salt monomers and all the butyl methacrylate monomers. The molar ratio (expressed as mol % of A1:mol % of B1:mol % of C1) in the first copolymer was 20:80:0. The molar ratio (expressed as mol % of A2:mol % of B2:mol % of C2) in the second copolymer was 20:0:80. In Paint 2b, there was only one copolymer which was made up from 20 mol % of salt monomer: 40 mol % of butyl methacrylate: 40 mol % of isobornyl methacrylate.