Antifouling composition

Abstract

The present invention relates to the use of polyoxalates as binders for antifouling coating compositions and antifouling coating compositions comprising the polyoxalates.

Claims

1. A marine antifouling coating composition comprising at least one hydrolyzable linear polyoxalate and at least one compound in the amount of 0.5% to 80% by weight of the composition that prevents the settlement of marine organisms on a surface and/or prevents the growth of marine organisms on a surface and/or encourages the dislodgement of marine organisms from a surface, where the linear polyoxalate is a polycondensation reaction product of a dialkyl oxalate with at least one diol.

2. The composition of claim 1, wherein the molar ratio in the polycondensation reaction between the dialkyl oxalate and diol is less than 2.0 and more than 0.5.

3. The composition of claim 1, wherein the diol is saturated and aliphatic.

4. The composition of claim 1, wherein the diol is an aromatic diol and comprises 50 mol % or less of the total amount of diols used in the polycondensation reaction.

5. The composition of claim 1, wherein the diol is an unsaturated aliphatic diol and comprises 10 mol % or less of total amount of diols used in the polycondensation reaction.

6. The composition of claim 1, wherein the polyoxalate comprises repeating units derived from polyols with more than two hydroxyl groups.

7. The composition of claim 6, wherein polyols form 10 mol % or less of the total amount of diols and polyols present in the polycondensation reaction.

8. The composition of claim 1, wherein the polyoxalate comprises one or more units obtained by the polycondensation reaction of a diamine, dicarboxylic acid or derivatives thereof or hydroxyl functional carboxylic acid or derivatives thereof.

9. The composition of claim 1 wherein the polyoxalate has a weight average molecular weight (Mw) from 1,000 to 40,000.

10. The composition of claim 1, wherein the composition further comprises one or more solvents.

11. The composition of claim 1, wherein the composition further includes one or more additives selected from the group consisting of binders, plasticizers, pigments, extenders, fillers, dehydrating agents, drying agents, curing agents, thixotropic agents, thickening agents, anti-settling agents, reinforcing agents, thinners and additional solvents.

12. The composition of claim 1, wherein the composition is a physical drying coating composition.

13. The composition of claim 1, wherein the composition is a curing coating composition.

14. The composition of claim 1, wherein the polyoxalate has hydroxy-functional end-groups, and the composition comprises a curing agent selected from the group consisting of isocyanates, polymeric isocyanates and isocyanate prepolymers.

15. The composition of claim 1, wherein the polyoxalate has epoxy-functional end-groups and the composition comprises a curing agent selected from the group consisting of amines and polyamines.

16. The composition of claim 1, wherein the composition has a solids content of not less than 50% by weight.

17. The composition of claim 1, wherein the composition has a volatile organic compounds (VOC) content below 400 g/L.

18. The composition of claim 1, wherein the at least one polyoxalate is amorphous.

19. A kit comprising (I) the marine anti-fouling coating composition of claim 1 and (II) at least one curing agent.

20. The composition of claim 1, wherein polyoxalate is produced by the condensation polymerisation of at least one oxalic acid or derivative thereof and at least two diols wherein at least one of said diols is a saturated branched diol having up to 20 carbon atoms.

21. An object coated with the marine antifouling coating of claim 1.

22. A process for protecting an object from fouling comprising coating at least a part of said object with the marine anti-fouling coating of claim 1.

23. A self-polishing marine anti-fouling coating composition of claim 1 which is curable or which has been cured.

24. The composition of claim 1, wherein the compound is selected from copper, copper oxide, copper thiocyanate, copper pyrithione, 2-(tert-butylamino)-4-(cyclopropylamino-6-(methylthio)-1,3,5-triazine), 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, N-dichlorofluoromethylthio-N,N-dimethyl-N-phenylsulfaminde, N-dichlorofluoromethylthio-N,N-dimethyl-N-p-tolylsulfamide, zinc pyrithione, zinc ethylenebis(dithiocarbamate) and medetomidine.

25. The composition of claim 1, wherein the dialkyl oxalate is dimethyl oxalate or diethyl oxalate.

Description

Example 1

General Procedure for Preparation of Polyoxalates by Transesterification in Melt

(1) 100 g of starting materials comprising a mixture of 1.0 mole eq. of diethyl oxalate or a mixture of diethyl oxalate and a dicarboxylic acid ester, 1.0 mole eq. of one or more diols and 0.02 mole eq. of catalyst are charged into a 500 ml three-necked glass flask equipped with magnetic stirrer, thermometer, condenser and nitrogen inlet. The mixture is heated slowly under nitrogen to 190 C. on a temperature controlled oil bath while the condensate is distilled. The heating rate is controlled so that the temperature in the outlet does not exceed the boiling point of the condensate. The temperature is maintained at 190 C. until 80-90% of the theoretical amount of condensate is collected. The nitrogen inlet is closed and vacuum is applied. The vacuum is adjusted gradually down to 0.1 mbar. The temperature is maintained at 190 C. for 2-4 hours. The polymer melt is cooled to approx. 100 C. under vacuum. The vacuum is removed and solvent is added. The polymer solution is cooled to room temperature.

(2) The polyoxalates PO-1 to PO-4 in Table 1 are prepared according to this procedure.

(3) TABLE-US-00001 TABLE 1 Ingredients and properties of polyoxalate solutions PO-1 to PO-4 PO-1 PO-2 PO-3 PO-4 Reactor Dicarboxylic Diethyl oxalate 54.06 50.13 50.09 30.14 charge (g) acid esters Dimethyl isophthalate 21.56 Diols 1,4-Cyclohexanedimethanol 26.67 21.27 14.83 22.88 Neopentyl glycol 19.26 2,2,4-Trimethyl-1,3- 28.59 35.08 pentanediol 2-Butyl-2-ethyl-1,3- 25.42 propanediol 1,6-Hexanediol Catalyst Dibutyltin oxide 0.0376 0.0349 0.0348 0.0322 Thinning (g) Solvent Xylene 43.94 45.59 45.61 49.25 Properties of Theoretical NVM (wt %) 60 60 60 60 polymer Actual NVM (wt %) 59.4 58.1 57.2 59.5 solutions Viscosity (cP) 7,050 2,200 1,250 2,750 Mw (1000) 24.1 23.4 18.6 12.8 Mn (1000) 8.3 5.6 4.7 5.0 PDI 2.9 4.2 4.0 2.6 Tg ( C.) 15 15 12 14

Example 2

General Procedure for Preparation of Polyoxalates by Transesterification in Melt

(4) 250 g of starting materials comprising a mixture of 1.0 mole eq. of diethyl oxalate or a mixture of diethyl oxalate and a dicarboxylic acid ester, 1.05 mole eq. of one or more diols and 0.02 mole eq. of catalyst are charged into a 250 ml temperature controlled reactor vessel equipped with mechanical stirrer, thermometer, condenser and nitrogen inlet. The mixture is heated slowly under nitrogen to 190 C. while the condensate is distilled. The heating rate is controlled so that the temperature in the outlet does not exceed the boiling point of the condensate. The pre-polymerisation reaction is run until 80-90% of the theoretical amount of condensate is collected. The nitrogen inlet is closed and vacuum is applied. The vacuum is adjusted gradually down to 100 mbar. The temperature and vacuum is maintained for 3 hours. The polymer melt is cooled to approx. 100 C. under vacuum. The vacuum is removed and solvent is added. The polymer solution is cooled to room temperature.

(5) The polyoxalates PO-5 to PO-19 in Table 2 are prepared according to this procedure.

(6) TABLE-US-00002 TABLE 2 Ingredients and properties of polyoxalate solutions PO-5 to PO-19 PO-5 PO-6 PO-7 PO-8 PO-9 Reactor Dicarboxylic Diethyl oxalate 122.19 118.83 119.25 124.20 116.05 charge acid esters Dimethyl (g) isophthalate Diols 1,4- 63.46 61.93 Cyclohexanedimethanol Neopentyl glycol 32.61 2,2,4-Trimethyl- 64.35 62.58 1,3-pentanediol 2-Butyl-2-ethyl- 68.58 68.82 93.19 133.95 1,3-propanediol Hydroxypivalyl hydroxypivalate 1,6-Hexanediol 1,4-Butanediol Catalyst Dibutyltin oxide 0.0872 0.0848 0.0851 0.0886 Titanium(IV) 0.1144 butoxide Thinning Solvent Xylene 74.13 75.03 74.92 73.58 75.79 (g) Properties Theoretical NVM (wt %) 70 70 70 70 70 of Actual NVM (wt %) 65.7 65.5 67.8 67.1 66.4 polymer Viscosity (cP) 470 125 1067 285 235 solutions Mw (1000) 4.7 3.5 6.4 3.9 3.8 Mn (1000) 2.2 1.6 2.7 1.8 1.8 PDI 2.2 2.1 2.4 2.1 2.2 Tg ( C.) 9 9 2 9 13 PO-10 PO-11 PO-12 PO-13 PO-14 Reactor Dicarboxylic Diethyl oxalate 119.67 117.23 135.05 131.46 128.06 charge acid esters Dimethyl (g) isophthalate Diols 1,4- 37.29 Cyclohexanedimethanol Neopentyl glycol 31.42 21.99 50.66 2,2,4-Trimethyl- 35.56 67.44 1,3-pentanediol 2-Butyl-2-ethyl- 67.66 131.46 1,3-propanediol Hydroxypivalyl 61.62 43.12 hydroxypivalate 1,6-Hexanediol 28.74 54.50 1,4-Butanediol 42.67 2-Ethyl-1,3- hexanediol Bisphenol A Catalyst Dibutyltin oxide 0.0964 0.0914 Titanium(IV) 0.1179 0.1456 0.1296 butoxide Tin(II) 2- ethylhexanoate Thinning Solvent Xylene 74.81 75.47 70.65 71.62 72.54 (g) Properties Theoretical NVM (wt %) 70 70 70 70 70 of Actual NVM (wt %) 67.6 67.1 64.8 66.4 64.8 polymer Viscosity (cP) 495 200 250 310 200 solutions Mw (1000) 4.1 3.6 4.4 5.8 4.6 Mn (1000) 2.2 1.8 1.9 2.5 2.0 PDI 1.9 2.0 2.3 2.3 2.3 Tg ( C.) 1 9 15 20 30 PO-15 PO-16 PO-17 PO-18 PO-19 Reactor Dicarboxylic Diethyl oxalate 132.67 140.37 135.83 120.96 70.65 charge acid esters Dimethyl 54.76 (g) isophthalate Diols 1,4- 40.67 Cyclohexanedimethanol Neopentyl glycol 29.86 31.59 2,2,4-Trimethyl- 1,3-pentanediol 2-Butyl-2-ethyl- 53.60 62.83 83.93 1,3-propanediol Hydroxypivalyl hydroxypivalate 1,6-Hexanediol 33.88 46.33 1,4-Butanediol 27.34 44.09 2-Ethyl-1,3- 50.70 70.08 hexanediol Bisphenol A 7.96 Catalyst Dibutyltin oxide 0.0976 0.0969 0.0798 Titanium(IV) 0.1274 butoxide Tin(II) 2- 0.1377 ethylhexanoate Thinning Solvent Xylene 71.29 69.21 70.44 67.01 80.31 (g) Properties Theoretical NVM (wt %) 70 70 70 70 70 of Actual NVM (wt %) 68.1 65.4 64.4 69.3 65.9 polymer Viscosity (cP) 350 240 173 338 490 solutions Mw (1000) 5.5 4.2 3.7 5.7 3.5 Mn (1000) 2.4 2.0 1.8 2.5 2.0 PDI 2.3 2.2 2.0 2.2 1.8 Tg ( C.) 22 17 25 27 9

Example 3

Procedure for Preparation of Polyoxalates by Esterification in Melt

(7) 54.0 g of oxalic acid, 45.5 g of 1,4-cyclohexanedimethanol, 50.5 g of 2-butyl-2-ethyl-1,3-propanediol, 0.498 g of tin(II) 2-ethylhexanate and 5.0 g of xylene were charged into a 250 ml temperature controlled reactor vessel equipped with mechanical stirrer, thermometer, condenser, water trap and nitrogen inlet. The mixture is heated slowly under nitrogen until reflux. The temperature was adjusted continuously to maintain the reflux until the temperature in the reactor vessel reached 210 C. The temperature was kept at 210 C. for 3.5 hours. Approx. 90% of the theoretical amount of water was collected in the water trap. The polymer melt was cooled to approx. 100 C. and 85.9 g of xylene was added. The polymer solution was cooled to room temperature.

(8) The obtained polyoxalate had Mw of 2,800, PDI of 1.9.

Example 4

General Procedure for Preparation of Antifouling Coating Composition

(9) The ingredients are mixed and ground to a fineness of <30 m using a high-speed disperser. Any ingredients sensitive to the high shear forces and temperature in the grinding process are added in the let-down. The compositions of the prepared coating compositions are presented in Table 3 and Table 4. Any curing agent and accelerator are mixed with the coating composition just before use.

(10) Determination of the Viscosity of the Antifouling Coating Composition

(11) The high-shear viscosity of the antifouling coating composition is determined in accordance with ASTM D4287 using a cone-plate viscometer.

(12) Calculation of the Volatile Organic Compound (VOC) Content of the Antifouling Coating Composition

(13) The volatile organic compound (VOC) content of the antifouling coating composition is calculated in accordance with ASTM D5201.

(14) Determination of Polishing Rates of Antifouling Coating Films in Sea Water

(15) The polishing rate is determined by measuring the reduction in film thickness of a coating film over time. For this test PVC disc are used. The coating compositions are applied as radial stripes on the disc using a film applicator. The thickness of the dry coating films are measured by means of a suitable electronic film thickness gauge. The PVC discs are mounted on a shaft and rotated in a container in which seawater is flowing through. Natural seawater which has been filtered and temperature-adjusted to 25 C.2 C. is used. The PVC discs are taken out at regular intervals for measuring the film thickness. The discs are rinsed and allowed to dry overnight at room temperature before measuring the film thickness.

(16) TABLE-US-00003 TABLE 3 Ingredients in parts by weight of physically drying coating compositions C-1 to C-3 C-1 C-2 C-3 Binder Polyoxalate solution PO-1 PO-3 PO-4 30.68 31.85 30.63 Biocides Cuprous oxide 36.72 36.71 36.72 Copper pyrithione 1.35 1.35 1.35 Pigments Iron oxide red 1.21 1.21 1.21 Titanium dioxide 1.18 1.18 1.18 Extenders Zinc oxide red seal 0.97 0.97 0.97 Barium sulfate 9.57 9.57 9.57 Nepheline syenite 2.95 2.95 2.95 Dehydrating Calcium sulfate 1.36 1.36 1.36 agent Thixotropic Disparlon A603-20X.sup.(1) 1.92 1.92 1.92 agents Disparlon 4401-25X.sup.(2) 0.88 0.88 0.88 Solvents Xylene 5.46 4.30 5.51 Solvesso 100 5.75 5.75 5.75 Coating Viscosity (cP) 620 200 260 properties Calculated VOC (g/L) 450 450 450 Polishing rate (m/month) 5.1 2.3 2.1 .sup.(1)Disparlon A603-20X is an amide wax, 20% in xylene; produced by Kusumoto Chemicals, Ltd. .sup.(2)Disparlon 4401-25X is a polyethylene wax, 25% in xylene; produced by Kusumoto Chemicals, Ltd.

(17) TABLE-US-00004 TABLE 4 Ingredients in parts by weight of 2-component curable coating compositions C-4 to C-9 C-4 C-5 C-6 C-7 C-8 C-9 Binder Polyoxalate solution PO-5 PO-6 PO-7 PO-8 PO-9 PO-11 27.57 26.43 27.67 26.38 26.39 26.40 Biocides Cuprous oxide 39.63 39.62 39.77 39.75 39.63 39.74 Copper pyrithione 1.59 1.60 1.61 1.61 1.59 1.61 Pigments Iron oxide red 1.96 1.97 1.98 1.98 1.96 1.98 Titanium dioxide 1.00 1.00 1.00 1.00 1.00 1.00 Extenders Barium sulfate 7.44 7.44 7.46 7.46 7.44 7.46 Magnesium carbonate 5.18 5.18 5.20 5.19 5.17 5.19 Nepheline syenite 2.83 2.84 2.85 2.85 2.82 2.85 Dehydrating agents Calcium sulfate 1.20 1.21 1.21 1.21 1.20 1.21 Thixotropic agents Disparlon A603-20X .sup.(1) 2.09 2.08 2.08 2.08 2.09 2.08 Disparlon 4401-25X .sup.(2) 0.52 0.53 0.53 0.53 0.52 0.53 Solvents Xylene 4.64 4.65 5.02 4.96 5.02 4.95 Curing agent (comp. B) Desmodur N 75 BA .sup.(3) 4.37 5.47 3.61 5.01 5.17 5.01 Accelerator Dibutyltin dilaurate 250 ppm 250 ppm 250 ppm 250 ppm 350 ppm 350 ppm Coating properties Calculated VOC (g/L) 335 335 335 335 335 335 Polishing rate (m/month) 3.7 3.6 3.0 4.4 2.8 5.2 .sup.(1) Disparlon A603-20X is an amide wax, 20% in xylene; produced by Kusumoto Chemicals, Ltd. .sup.(2) Disparlon 4401-25X is a polyethylene wax, 25% in xylene; produced by Kusumoto Chemicals, Ltd. .sup.(3) Desmodur N 75 BA is an aliphatic polyisocyanate resin based on hexamethylene diisocyanate (HDI), 75% in butyl acetate; produced by Bayer MaterialScience AG.
The polishing rate of the reference paint was 2.3 m/month when tested in parallel with the coatings in Table 3 and Table 4. The reference paint is SeaQuantum Classic light red from Jotun AS, which is a high performance self-polishing antifouling coating, based on a hydrolysing organosiylyl polymer as binder.
The data shows that an antifouling system comprising a polyoxalate binder is self-polishing. The self-polishing allows a controlled leaching of biocide that would keep a surface free of marine organisms. Our results show that the polyoxalate binder of this invention polishes faster than a reference commercial silyl ester copolymer binder containing fouling composition.

(18) A faster polishing system may be advantageously utilised on stationary installations or vessels that move slowly (e.g. less than 10 knots) and/or that operate in cold water (e.g. less than 10 C.) since the hydrolysis rate is dependent on temperature.