Antifouling composition

Abstract

The invention relates to a waterborne antifouling coating composition comprising: i) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; ii) one or more monocarboxylic acids or metal salts thereof; and iii) less than 8.0 wt%, relative to the total weight of the composition as a whole, of biocides, wherein said biocides comprise: a. tralopyril; and b. one or more copper compounds having a copper content of at least 40 wt%, relative to the formula weight of the copper compound; wherein the coating composition comprises at least 5 wt% water relative to the total weight of the composition as a whole.

Description

[0001] P2409 Antifouling Composition 173386 / 01

[0002] Field of the Invention

[0003] The present invention relates to marine antifouling coating compositions, more specifically to waterborne antifouling coating compositions comprising biocides in an amount of 8.0 wt% or less, wherein the biocides comprise tralopyril and a copper compound having a copper content of at least 40 wt%. The compositions additionally contain one or more monocarboxylic acids or metal salts thereof, a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer and at least 5 wt% water relative to the total weight of the composition as a whole. The invention further relates to a method of protecting objects from fouling, and to objects coated with the antifouling composition of the invention.

[0004] Background of invention

[0005] Surfaces that are submerged in seawater are subjected to fouling by marine organisms such as green and brown algae, barnacles, mussels, tube worms and the like. On marine constructions such as vessels, oil platforms, buoys, etc. such fouling is undesired and has economic consequences. The fouling may lead to biological degradation of the surface, increased load and accelerated corrosion. On vessels the fouling will increase the frictional resistance which will cause reduced speed and / or increased fuel consumption.

[0006] To prevent settlement and growth of marine organisms, antifouling paints are used. These paints generally comprise a film-forming binder, together with different components such as pigments, extenders, additives and solvents together with biologically active substances (biocides). Biocides can be broadly divided into those active against soft fouling, such as green and brown algae, grass, slime and those active against hard fouling, such as barnacles, mussels, tube worms etc.

[0007] Commercial vessels (e.g. container ships, bulk carriers, tankers, passenger ships) often operate in different waters, in different trade, with different activity, including idle periods. The antifouling coating should provide good fouling protection under all those conditions. Typical service intervals for commercial vessels are from 30 to 90 months. Maintenance of submerged objects is costly, so the applied antifouling coatings should be effective for the specified service interval. It requires a controlled degradation of the coating film giving constant release of biocides to protect the object through the full service interval and under various sailing conditions.

[0008] This can best be obtained by using a self-polishing antifouling coating having a controlled polishing rate. Too fast polishing will lead to a rapid consumption of the coating film, resulting in an unprotected surface. Too slow polishing will lead to insufficient release of the biocide, which is vital for effective protection from fouling. A controlled degradation over the lifetime of the coating will give a constant release of biocides and thereby excellent fouling protection.

[0009] In addition to these demands, the coating industry is constantly faced with stricter VOC regulations, which limits the amount of organic solvents that can be used in antifouling paints. The most common application methods for antifouling coatings are airless spray, brush or roller. It is important that the paint can be applied by standard techniques which in turn means coating compositions and paints having a certain viscosity level, whilst minimising their VOC content and still achieving satisfactory application properties. The VOC limits may be exceeded if additional solvent must be added to reduce the viscosity at the point of application.

[0010] It is a challenge to find coating compositions which comply with the ever tightening VOC regulations and which also have controlled polishing properties, good mechanical properties and exhibit good fouling protection.

[0011] One solution for achieving VOC compliant and more sustainable antifouling paints is to use waterborne technology. The waterborne market will likely increase to offer more sustainable coatings to meet VOC / HAP regulations. Water-based paints have gained popularity in the interior market due to low odour, easier clean-up, faster drying and that it is healthier for staff. The advances in newer technology lead to performance and durability of waterborne coatings being closer to solvent-borne coatings for most applications.

[0012] Waterborne coatings are described in, for example, US 2021 / 0301153, US 4052354 and WO 2012 / 084758. These include coatings based on (meth)acrylic binders.

[0013] Furthermore, WO2023 / 232825 relates to waterborne antifouling coating compositions comprising (a) a polymeric binder and (b) at least 1.0 wt% of a rosin ester, relative to dry weight of the total coating composition. Similarly, JP2009173914 and W02012 / 150360 both disclose waterborne antifouling coating compositions for use on underwater surfaces to prevent fouling by marine organisms.

[0014] There is, however, a constant demand in the industry for the development of new and improved coatings, especially coatings with lower amounts of biocides present. Additionally, there is a limited number of biocides approved for use as marine antifouling agents by regulatory bodies. The approved biocides are considered safe to use and without adverse environmental effects. However, it is still important to optimize the effect of the combination of biocides in the coating film to limit their use to a minimum.

[0015] Restrictions on the use of biocides are increasing and it is likely that in the future the amounts of biocides in antifouling coatings will have to be significantly reduced. When reducing the amounts of biocides there is a challenge in maintaining good long-term antifouling performance.

[0016] Reducing the biocide to low levels in conventional antifouling coatings generally requires a full or part replacement of biocides by other components. That will have consequences for the self-polishing properties, mechanical properties and antifouling performance of the coating, unless the formulation is carefully re-designed. There thus remains a need to develop new self-polishing antifouling coating compositions which contain reduced levels of biocides.

[0017] Tralopyril is a relatively new metal-free, organic marine antifouling agent which has a broad spectrum of activity against hard-shelled and soft-bodied invertebrates such as barnacles, hydroids, mussels, oysters, tube worms and tunicates. Tralopyril is sold under the trade name Econea and the supplier’s product datasheet recommends using between 4 and 6 wt% in antifouling coating compositions. When lower amounts of tralopyril are used as the only biocide active against hard fouling, there is a challenge with achieving sufficient antifouling performance.

[0018] Inorganic copper compounds, such as copper(I) oxide, copper metal and copper(I) thiocyanate, are widely used against marine fouling and known for having activity towards a wide spectrum of fouling organisms, such as barnacles, tube worms and to some degree algae. In general, inorganic copper compounds are used in large quantites to obtain satisfactory protection against marine fouling. Organic copper complexes, such as copper pyrithione, are active against algae and slime at low concentrations and are often used in combination with inorganic copper compounds.

[0019] The present inventors have surprisingly found that by combining tralopyril with copper compound(s) as defined herein, self-polishing waterborne antifouling coating compositions with less than 8.0 wt% total biocides can be prepared. Such coating compositions have unexpectedly attractive antifouling properties as well as excellent mechanical properties in salt and fresh water over time. Such coating compositions also advantageously have very low VOC content and can have very low biocide content, meeting the strict environmental regulations for both VOC content and biocide content levels.

[0020] Summary of invention

[0021] In one aspect, the invention relates to a waterborne antifouling coating composition comprising: i) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; ii) one or more monocarboxylic acids or metal salts thereof; and iii) less than 8.0 wt%, relative to the total weight of the composition as a whole, of biocides, wherein said biocides comprise: a. tralopyril; and b. one or more copper compounds having a copper content of at least 40 wt%, relative to the formula weight of the copper compound; wherein the coating composition comprises at least 5 wt% water relative to the total weight of the composition as a whole.

[0022] In another aspect, the invention relates to a process for applying a waterborne antifouling coating composition to a substrate comprising applying, e.g. by spraying, the waterborne antifouling coating composition as hereinbefore defined to a substrate and allowing the coating composition to dry.

[0023] In another aspect, the invention relates to a substrate coated with the waterborne antifouling coating composition as hereinbefore defined.

[0024] Definitions

[0025] The terms “marine antifouling coating composition”, “antifouling coating composition” or simply “coating composition” refer to a composition that, when applied to a surface, prevents or minimises growth of marine organisms on the surface.

[0026] As used herein, the term “waterborne composition” refers to a composition which comprises water as the main solvent. Typically, water forms at least 50 wt% of the solvent used, preferably more than 70 wt%, more preferably more than 80 wt%, particularly preferred more than 90 wt%. As used herein the term “paint” refers to a composition comprising the antifouling coating composition as herein described and optionally solvent which is ready for use, e.g. for spraying. Thus, the antifouling coating composition may itself be a paint or the antifouling coating composition may be a concentrate to which solvent is added to produce a paint.

[0027] The term “(meth)acrylate” means a methacrylate or acrylate.

[0028] As used herein the term “alkyl” refers to saturated, straight chained, branched or cyclic groups.

[0029] As used herein the term “cycloalkyl” refers to a cyclic alkyl group.

[0030] As used herein the term “alkylene” refers to a bivalent alkyl group.

[0031] As used herein the term “aryl” refers to a group comprising at least one aromatic ring. The term aryl encompasses fused ring systems wherein one or more aromatic ring is fused to a cycloalkyl ring. An example of an aryl group is phenyl, i.e. CeHs.

[0032] As used herein the term “alkaryl” refers to a group comprising an aromatic ring that is substituted with an alkyl radical. An example is methyl-, ethyl- or higher alkyl phenyls.

[0033] As used herein the term "substituted" refers to a group wherein one or more, for example up to 6, more particularly 1, 2, 3, 4, 5 or 6, of the hydrogen atoms in the group are replaced independently of each other by the corresponding number of the described substituents.

[0034] As used herein the term “arylalkyl” group refers to structural motifs comprising an aromatic ring with at least one alkyl moiety attached to the aromatic ring and wherein substituent e.g., amines are attached to the alkyl portion.

[0035] As used herein the term “poly ether” refers to a compound comprising two or more -O- linkages interrupted by alkylene units.

[0036] As used herein the term “monocarboxylic acid” refers to a compound comprising one -COOH group.

[0037] As used herein the term “resin acid” and “rosin acid” refers to a mixture of carboxylic acids present in resins.

[0038] The term “binder system” defines the part of the composition which includes the polymeric binder and any other polymers, resins or components which together form a matrix giving substance and strength to the composition. The monocarboxylic acids or salts thereof of the present invention are regarded as part of the binder system.

[0039] The term “Tg” means glass transition temperature, obtained by Differential Scanning Calorimetry (DSC) measurements. Where a wt% of a given monomer is given, the wt% is relative to the total (weight) of each monomer present in the copolymer.

[0040] The term “wt% relative to the total weight of the composition as a whole” or “wt% relative to the total weight of the composition” refers to the wt% of a component present in the final, ready to use, composition, unless otherwise specified.

[0041] The term “wt% relative to the total dry weight of the composition” refers to the wt% of a component present in the composition relative to the total weight of the components in the composition not including the solvents.

[0042] As used herein the term “dispersion” refers to a fine dispersion of particles or droplets dispersed in a continuous liquid phase. Typically, the continuous liquid phase is water. Thus, the dispersions employed in the present invention may also be termed “aqueous dispersions”, meaning that they are dispersions wherein the continuous phase (i.e. the solvent) is water.

[0043] Droplets dispersed in water can be referred to as an emulsion. As used herein, the term emulsion refers to a fine dispersion of droplets of one liquid in another in which it is not soluble or miscible. In the present invention the term “dispersion” refers to both particles and droplets (emulsions) dispersed in water.

[0044] As used herein the term “volatile organic compound (VOC)” refers to an organic compound having a boiling point of 250 °C or less at 101.3 kPa.

[0045] As used herein “antifouling agent” or “biocide” refers to a biologically active compound or mixture of biologically active compounds that prevents the settlement of marine organisms on a surface, and / or prevents the growth or marine organisms on a surface and / or encourages the dislodgement of marine organisms on a surface. These terms are used interchangeably. A biocide is defined by the European biocidal products regulation (BPR) as an active substance intended to destroy, deter, render harmless, prevent the action of, or otherwise exert a controlling effect on any harmful organism by chemical or biological means.

[0046] Detailed description of invention

[0047] The present invention relates to a waterborne antifouling coating composition comprising (i) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer, (ii) one or more monocarboxylic acids or metal salts thereof; and (iii) less than 8.0 wt%, relative to the total weight of the composition as a whole, of biocides, wherein said biocides comprise (a) tralopyril and (b) one or more copper compounds having a copper content of at least 40 wt%, relative to the formula weight of the copper compound, wherein the coating composition comprises at least 5 wt% water relative to the total weight of the composition as a whole.

[0048] Polymeric Binder (i)

[0049] The coating composition of the present invention comprises a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer. The polymeric binder as defined above will herein be referred to as the “polymeric binder”.

[0050] Examples of suitable ethylenically unsaturated monomers are (meth)acrylic acid, (meth)acrylic acid esters, (meth)acrylic acid amide, vinyl chloride, vinyl ester, vinyl acetate, vinyl propionatemaleic acid, itaconic acid, vinyl alcohol, styrene, a-methyl styrene, alkyl vinyl ether, vinyl pyrrolidone, N-vinyl caprolactame, N-methyl-N-vinylacetamide and (meth)acrylonitrile.

[0051] Preferably the ethylenically unsaturated monomer is selected from (meth)acrylic acid, (meth)acrylic acid esters, (meth)acrylic acid amide and vinyl ester such as vinyl acetate and vinyl neodecanoate.

[0052] In a particularly preferred embodiment, the ethylenically unsaturated monomer is selected from (meth)acrylic acid and (meth)acrylic acid esters.

[0053] Examples of the (meth)acrylic acid ester monomers include: alkylate or cycloalkyl ester of (meth)acrylic acid having 1 to 18 carbon atoms such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n- hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and cyclohexyl (meth)acrylate; alkoxy alkyl ester of (meth)acrylic acid having 2 to 18 carbon atoms such as methoxybutyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, and ethoxybutyl (meth)acrylate; dialkylaminoalkyl ester of (meth)acrylic acid such as dimethylaminoethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, 2-(diisopropylamino)ethyl (meth)acrylate, 2-(tert-butylamino)ethyl (meth)acrylate, 4-dimethylaminobutyl (meth)acrylate and dimethylaminopropyl (meth)acrylate; hydroxy alkyl ester of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate, 2- hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxy-l -methylethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and hydroxyisobutyl (meth)acrylate; glycidyl (meth)acrylate, (2,2-dimethyl-l,3-dioxolan-4-yl)methyl (meth)acrylate;

[0054] (meth)acrylic acid ester monomers comprising cyclic amines such as (meth)acryloyl- 2-pyrrolidone;

[0055] (meth)acrylic acid ester monomers comprising polysiloxane groups such as monomethacryloxypropyl terminated polydimethylsiloxane, such as a- methacryloyloxypropyl-a>-butyl polydimethylsiloxane, a-methacryloyloxypropyl-a>- trimethyl silyl polydimethylsiloxane, a-methacryloyloxyethyl-co-trimethylsilyl polydimethylsiloxane, a-acryloyloxypropyl-a> -butyl polydimethylsiloxane, a- acryloyloxypropyl-a> -trimethyl silyl poly dimethylsiloxane, a-acryloyloxyethyl-a>- trimethyl silyl polydimethylsiloxane. Representative examples of commercially available monomers comprising polysiloxane groups include X-22-174ASX, X22-174BX, KF-2012, X-22-2426 and X-22-2404 from Shin-Etsu, Silaplane FM-0711, Silaplane FM-0721, Silaplane FM-0725 from JNC Corporation, PS560 from United Chemical Technologies and MCR-M07, MCR-M11, MCR-M17, MCR-M22 and MCR-V41 from Gelest;

[0056] (meth)acrylic acid momomers comprising polyether groups such as polyethylene glycol)methyl ether (meth)acrylate, polypropylene glycol) methyl ether (meth)acrylate, poly(ethylene glycol) ethyl ether (meth)acrylate, polypropylene glycol) ethyl ether (meth)acrylate, poly(ethylene glycol) (meth)acrylate, polypropylene glycol) (meth)acrylate. Representative examples of commercially available monomers include Visiomer MPEG 750 MA W, Visiomer MPEG 1005 MA W, Visiomer MPEG 2005 MA W, Visiomer MPEG 5005 MA W from Evonik, Bisomer PPA6, Bisomer PEA6, Bisomer PEM6, Bisomer PPM5, Bisomer PEM63P, Bisomer MPEG350MA, Bisomer MPEG550MA, Bisomer SIOW, BisomerS20W from Geo Speciality Chemicals, SR550 MPEG350MA, SR552 MPEG500MA from Sartomer and RPEG 750 from Ineos Oxide;

[0057] (meth)acrylic acid ester monomers that are hydrolysable such as silyl (meth)acrylate monomers and metal ester (meth)acrylic monomers. Examples of such monomers are trialkyl silyl monomers such as triisopropyl silyl (meth)acrylate, zinc (meth)acrylate and zinc acetate (meth)acrylate, copper (meth)acrylate and copper acetate (meth)acrylate.

[0058] In one particularly preferred embodiment, the polymeric binder comprises a residue of at least one, and preferably at least two, monomers of formula (I) wherein R1is H or CH3;

[0059] R2is H or optionally a linear, branched or cyclic substituted C1-18 alkyl, wherein said substituents are selected from OH, OR3and N(R4)?; and

[0060] R3is selected from C1-8 alkyl and C3-8 cycloalkyl.

[0061] Each R4is independently selected from H, C1-8 alkyl and C3-8 cycloalkyl.

[0062] It is to be understood that the polymeric binder of the present invention may be a copolymer comprising several of the monomers described above.

[0063] The polymeric binder of the present invention preferably comprises at least 50 wt% of the structural unit derived from an ethylenically unsaturated monomer, preferably at least 70 wt%, more preferred at least 80 wt% relative to the total weight of the polymeric binder. In one preferred embodiment the polymeric binder of the present invention comprises at least 95 wt% of the structural units derived from ethylenically unsaturated monomers, preferably 100 wt%.

[0064] The polymeric binder of the present invention preferably comprises a (meth)acrylic acid and / or a (meth)acrylic acid ester monomer. Preferably the polymeric binder of the present invention comprises at least 15 wt%, relative to the total weight of the polymeric binder of (meth)acrylic acid and / or (meth)acrylic acid ester monomers, preferably at least 20 wt%, more preferably at least 40 wt%, still more preferably at least 55 wt%. In general, the (meth)acrylic acid and / or (meth)acrylic acid ester monomer is present in an amount of 99.9 wt% or less, more preferably 99.5 wt% or less, relative to the total weight of the polymeric binder.

[0065] The amount of each structural unit can be determined by, for example, nuclear magnetic resonance spectroscopy (NMR) or pyrolysis gas chromatography mass spectrometry (Pyro-GC / MS). Information about the wt% (meth)acrylic acid and / or (meth)acrylic acid ester parts in a commercially available polymeric binder is also often easily obtainable from the supplier.

[0066] The polymeric binder of the invention may be produced by methods known in the art. In general, this involves appropriately selecting one or more ethylenically unsaturated monomers, in amounts in consideration of, for example, the structural unit and weight average molecular weight, and then using a known method, for example, emulsion polymerization to polymerise said monomers.

[0067] The glass transition temperature (Tg) of the polymeric binder is not particularly limited and can be, for example, less than 50°C.

[0068] In a particularly preferred embodiment, the polymeric binder of the present invention is in the form of a dispersion.

[0069] The polymeric binder is typically present in the dispersion in the form of particles or droplets with an average size of 4 to 1000 nm, preferably 25 to 400 nm, more preferably 50 to 350 nm, such as 100 to 300 nm. The “average size” referred to in this context is the Z- average size, which will be understood to be the intensity weighted average hydrodynamic diameter as described in ISO22412:2017. It will be understood that in this context the polymeric binder particles form the dispersed phase of the dispersion.

[0070] The polymeric binder droplets or particles preferably form 10 to 80 wt% of the dispersion, relative to the total weight of the dispersion as a whole. Typical wt% ranges may be 35 to 60 wt%, such as 40 to 55 wt%, relative to the total weight of the dispersion as a whole.

[0071] In addition to the polymeric binder droplets or particles, the dispersion comprises an aqueous solvent (i.e. the continuous phase). It will be understood that an aqueous solvent is one comprising (preferably consisting of) water. The dispersion referred to herein may thus be termed an aqueous dispersion. The aqueous dispersion of the polymeric binder is a dispersion in which the polymeric binder is dispersed in a dispersion medium including water (hereinafter, also referred to as “aqueous medium”).

[0072] The aqueous medium is not particularly limited as long as it includes water; however, the content of water in the aqueous medium is preferably 50 to 100 wt%, and more preferably 60 to 90 wt% relative to the total weight of the aqueous medium. In one preferred embodiment the content of water in the aqueous medium is 100 wt%, e.g. the aqueous medium consists of water. The aqueous medium may include a medium other than water, and examples of such a medium include acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-methoxyethanol, 2- eth oxyethanol, 2-butoxyethanol, l-methoxy-2-propanol, l-ethoxy-2-propanol, diacetone alcohol, dioxane, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropylene glycol monomethyl ether (Dowanol DPM), ethylene glycol monopropyl ether, and ethylene glycol monohexyl ether. One or more of these can be used. The solvent (preferably water) forms 10 to 70% of the volume of the dispersion, relative to the total volume of the dispersion as a whole. Typical volume% ranges may be 20 to 65%, such as 30 to 60%, relative to the total volume of the dispersion as a whole.

[0073] The dispersion may be prepared by any suitable known method in the art.

[0074] The dispersion may comprise a surfactant. The surfactant may be non-ionic, anionic, cationic or amphoteric.

[0075] Examples of non-ionic surfactants are alkyl phenoxy ethers, polyalkylene glycols, polyoxyalkylene sorbitan monooleates, polyvinyl alcohols, polyvinyl esters, polyether siloxanes, fatty alcohol ethoxylates and sorbitan stearates. Preferred non-ionic emulsifying agents are polyalkylene glycols such as polyoxy ethylene-polyoxypropylene co-polymers and fatty alcohol ethoxylates.

[0076] Examples of anionic surfactants are alkyl-, aryl-, alkaryl- sulphates, sulphonates, phosphates, sulpho-succinates, sulphosuccinamates, sulphoacetates and amino acid derivatives.

[0077] Particularly preferred anionic surfactants are alkylsulfate salts, polyoxyethylene alkyl ether sulfate salts, unsaturated aliphatic sulfonate salts, and hydroxylated aliphatic sulfonate salts. The alkyl group referenced here can be exemplified by medium and higher alkyl groups such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, cetyl, stearyl, and so forth. The unsaturated aliphatic group can be exemplified by oleyl, nonenyl, and octynyl. The counterion can be exemplified by sodium ion, potassium ion, lithium ion, and ammonium ion, with the sodium ion being typically used among these.

[0078] The cationic surfactant can be exemplified by quaternary ammonium salt-type surfactants such as alkyltrimethylammonium salts, e.g., octadecyltrimethylammonium chloride and hexadecyltrimethylammonium chloride, and dialkyldimethylammonium salts, e.g., dioctadecyldimethylammonium chloride, dihexadecyldimethylammonium chloride and didecyldimethylammonium chloride.

[0079] The amphoteric surfactant can be exemplified by alkylbetaines and alkylimidazolines.

[0080] The dispersions may also comprise crosslinkers, curing catalysts, antifoaming agents, rheology modifiers and pH adjusting agents. Suitable antifoaming agents, rheology modifiers and pH adjusting agents are described further under additives.

[0081] From the viewpoint of the stability of the dispersion, the volume solid is preferably 30% or more, more preferably 40 wt% or more, relative to the total volume of the dispersion. Typically, the volume solid is 80% or less, preferably 70% or less, relative to the total volume solid of the dispersion as a whole. Example of suitable commercially available dispersions include PRIMAL™ AC-337, PRIMAL™ SF-021 and MAINCOTE™ 1071 from Dow Chemical company.

[0082] An aqueous dispersion of the polymeric binder can be prepared by dispersing the polymeric binder with a surfactant to form a dispersion. In addition, a dispersion can be directly prepared by emulsion polymerisation of the monomers forming the polymeric binder. The surfactant is not particularly limited, and can be appropriately selected from a cationic surfactant, an anionic surfactant, and a nonionic surfactant as described above.

[0083] The polymeric binder preferably forms 1.0 to 30 wt% of the antifouling coating composition, relative to the total weight of the composition as a whole. Further preferred wt% ranges are 2.0 to 25 wt%, such as 2.5 to 20 wt%, more preferred 5.0 to 15 wt% relative to the total weight of the composition as a whole.

[0084] The amount of polymeric binder in the antifouling coating composition is preferably 2.0 to 35 wt%, more preferred 2.5 to 30 wt%, further preferred 3.0 to 25 wt%, most preferred 5.0 to 20.0 wt% of the total dry weight of the coating composition.

[0085] Monocarboxylic acid(s) (ii)

[0086] The antifouling coating composition of the invention further comprises one or more monocarboxylic acids or metal salts thereof.

[0087] The monocarboxylic acid present in the antifouling coating composition of the present invention is preferably selected from rosin, modified rosin, C6-C20 cyclic monocarboxylic acid, C5-C24 acyclic aliphatic monocarboxylic acid, C7-C20 aromatic monocarboxylic acid and metal salts thereof. Metal salts of monocarboxylic acids include alkali metal carboxylate, alkaline earth metal carboxylate (e.g. calcium carboxylate, magnesium carboxylate) and transition metal carboxylate (e.g. zinc carboxylate, copper carboxylate). Preferably the metal carboxylate is a transition metal carboxylate, particularly preferably the metal carboxylate is a zinc carboxylate or copper carboxylate. The metal carboxylate may be added directly to the antifouling coating composition or be generated in situ in the antifouling coating composition.

[0088] Representative examples of C6-C20 cyclic monocarboxylic acids include naphthenic acid, l,4-dimethyl-5-(3-methyl-2-butenyl)-3-cyclohexen-l-yl-carboxylic acid, 1,3- dimethy 1 -2-(3 -methy 1 -2-buteny 1 )-3 -cyclohex en- 1 -yl-carboxylic acid, 1,2,3 -trimethy 1 -5 -( 1 - methy 1 -2-propeny 1 )-3 -cyclohexen- 1 -yl-carboxylic acid, 1 ,4, 5-trimethy 1 -2-(2-methy 1 -2- propeny 1 )-3 -cyclohex en-l-yl-carboxylic acid, 1,4,5 -trimethy 1 -2-(2-methyl-l-propeny 1 )-3 - cyclohexen- 1 -yl-carboxylic acid, 1 , 5,6-trimethy 1 -3 -(2-methy 1-1 -property 1 )-4-cyclohexen- 1 - yl-carboxylic acid, l-methyl-4-(4-methyl-3-pentenyl)-4-cyclohexen-l -yl-carboxylic acid, 1- methy 1-3 -(4-methyl-3 -penteny 1 )-3 -cyclohex en-l-yl-carboxylic acid, 2-methoxy carbony 1 -3 - (2-methyl-l-propenyl)-5, 6-dimethyl-4-cyclohexen-l -yl-carboxylic acid, 1 -isopropyl -4- methylbicyclo[2,2,2]2-octen-5-yl-carboxylic acid, 1 -isopropyl -4-methyl-bicyclo[2, 2, 2]2- octen-6-yl-carboxylic acid, 6-isopropyl-3-methyl-bicyclo[2,2,2]2-octen-8-yl-carboxylic acid and 6-isopropyl-3-methyl-bicyclo[2,2,2]2-octen-7-yl-carboxylic acid.

[0089] Representative examples of C5-C24 acyclic aliphatic monocarboxylic acids include versatic acids, neodecanoic acid, 2,2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2- isopropylpentanoic acid, 2,5-dimethyl-2-ethylhexanoic acid, 2,2-dimethyloctanoic acid, 2,2- diethylhexanoic acid, pivalic acid, 2,2-dimethylpropionic acid, trimethylacetic acid, neopentanoic acid, 2-ethylhexanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid, isopalmitic acid, isostearic acid, 16-methylheptadecanoic acid and 12,15- dimethylhexadecanoic acid. The acyclic aliphatic monocarboxylic acid is preferably selected from liquid, acyclic C10-C24 monocarboxylic acids or liquid, branched C10-C24 monocarboxylic acids. It will be appreciated that many of the acyclic C10-C24 monocarboxylic acids may be derived from natural sources, in which case in isolated form they typically exist as a mixture of acids of differing chain lengths with varying degree of branching.

[0090] Preferably the monocarboxylic acids are selected from rosin, modified rosin, acyclic C10-C24 monocarboxylic acids, C6-C20 cyclic monocarboxylic acids or metal salts thereof.

[0091] It is preferred if the monocarboxylic acid is a rosin. Rosin is a mixture of monocarboxylic acids called resin acids. Resin acids are also referred to as rosin acids. Representative examples of resin acids include abietic acid, neoabietic acid, dehydroabietic acid, palustric acid, levopimaric acid, pimaric acid, isopimaric acid, sandaracopimaric acid, communic acid and mercusic acid, secodehydroabietic acid. It will be appreciated that rosins are derived from natural sources and as such they typically comprise a mixture of acids.

[0092] Representative examples of rosins include gum rosin, wood rosin and tall oil rosin. Gum rosin, also referred to as colophony and colophonium, is particularly preferred. Preferred rosins are those comprising more than 85% resin acids and still more preferably more than 90% resin acids.

[0093] Commercial grades of rosin acids, such as gum rosin, typically have an acid value from 155 to 180 mg KOH / g as specified in ASTM D465. Preferred rosin for the compositions of the invention has an acid value from 155 to 180 mg KOH / g, more preferred 160 to 175 mg KOH / g, even more preferred 160 to 170 mg KOH / g. Commercial grades of rosin typically have a softening point (Ring & Ball) of 70 °C to 80 °C as specified in ASTM E28. Preferred rosin for the compositions of the invention has a softening point of 70 °C to 80 °C, more preferred 75 °C to 80 °C.

[0094] Commercial grades of rosin acids are often classified according to its colour by designation of letters on a colour scale XC (lightest), XB, XA, X, WW, WG, N, M, K, I, H, G, F, E, D (darkest) as specified in ASTM D509. Preferred colour grades for the compositions of the invention are X, WW, WG, N, M, K, I, and still more preferably WW.

[0095] In one preferred embodiment the coating composition of the present invention comprises rosin acid. Typical amounts for the rosin acid, when present, are 0.1 to 15 wt%, such as 0.5 to 10 wt%, relative to the dry weight of the total composition.

[0096] When present, the rosin acid is typically present in the dispersion in the form of droplets or particles with an average size of 50 to 1500 nm, preferably 100 to 1200 nm, more preferably 150 to 1000 nm. The “average size” referred to in this context is the Z-average size, which will be understood to be the intensity weighted average hydrodynamic diameter as described in ISO22412:2017.

[0097] It will be understood that in this context the rosin acid droplets or particles form the dispersed phase of the dispersion.

[0098] The rosin acid droplets or particles preferably form 30 to 90 wt% of the dispersion, relative to the total weight of the dispersion as a whole. Typical wt% ranges may be 35 to 80 wt%, such as 40 to 70 wt%, relative to the total weight of the dispersion as a whole.

[0099] In addition to the rosin acid droplets or particles, the dispersion comprises aqueous solvent (i.e. the continuous phase). It will be understood that an aqueous solvent is one comprising (preferably consisting of) water. The dispersion referred to herein may thus be termed an aqueous dispersion. The aqueous dispersion of the rosin acid is a dispersion in which the rosin acid is dispersed in a dispersion medium including water (hereinafter, also referred to as “aqueous medium”).

[0100] The aqueous medium is as defined above for the dispersions of the polymeric binder.

[0101] The solvent (preferably water) forms 10 to 70 wt% of the dispersion, relative to the total weight of the dispersion as a whole. Typical wt% ranges may be 20 to 65 wt%, such as 30 to 60 wt%, relative to the total weight of the dispersion as a whole.

[0102] The dispersion may be prepared by any suitable known method in the art.

[0103] The dispersion of the rosin acid may also comprise surfactants, antifoaming agents, rheology modifiers and pH adjusting agents. Suitable antifoaming agents, rheology modifiers and pH adjusting agents are described further under additives. Suitable surfactants are as described for the polymeric binder above.

[0104] Rosin acid derivatives such as hydrogenated rosin acid, partially hydrogenated rosin acid, dimerized rosin acids and modified rosin acids (such as maleic and fumaric modified rosin acids) may also be present in the coating composition of the present invention. When present the rosin acid derivatives are preferably dispersed in water as described for the rosin acid above.

[0105] Typical amounts for the rosin acid derivatives, when present, are 0.1 to 15 wt%, such as 0.5 to 10 wt%, relative to the dry weight of the total composition.

[0106] Metal carboxylate salts of rosin acid and rosin acid derivatives may also be present in the antifouling coating composition of the present invention. Examples of metal carboxylate salts include alkali metal salts such as sodium and potassium carboxylate salt, alkaline earth metal carboxylate salt such as magnesium carboxylate salt and calcium carboxylate salt or transition metal carboxylate salt such as copper carboxylate salt and zinc carboxylate salt. Transition metal carboxylate salts are preferred such as rosin acid zinc salts (zinc rosinate) and rosin acid copper salts (copper rosinate). The metal carboxylate salts may be added directly to the antifouling coating composition or be generated in situ in the antifouling coating composition.

[0107] Representative examples of modified resin acids include dihydroabietic acids, dihydropimaric acids and tetrahydroabietic acids; and modified rosins such as partly hydrogenated rosin, fully hydrogenated rosin, disproportionated rosin.

[0108] More preferably, the monocarboxylic acid is rosin or a modified rosin or a metal salt thereof.

[0109] Further preferred the monocarboxylic acid or metal salt thereof is gum rosin, hydrogenated gum rosin, copper salt of gum rosin, zinc salt of gum rosin, copper salt of hydrogenated gum rosin, zinc salt of hydrogenated gum rosin and mixtures thereof. Gum rosin is most preferred.

[0110] A single rosin or salt thereof as defined above may be employed, or a mixture of two or more such rosins.

[0111] To ensure sufficient polishing and mechanical properties, the amount of monocarboxylic acid or metal salt thereof, preferably rosin, should be at least 1.0 wt%, relative to the total dry weight of the coating composition. Typical wt% ranges for the monocarboxylic acid or metal salt thereof, preferably rosin, are 1.0 to 30 wt%, such as 1.2 to 25 wt%, more preferably 1.5 to 20 wt%, even more preferably 2.0 to 15 wt%, relative to the total dry weight of the coating composition. Where the coating composition comprises more than one monocarboxylic acid or metal salt thereof, these wt% ranges will be understood to corresponds to the total for all monocarboxylic acids or metal salts thereof present.

[0112] Preferably the ratio between the one or more monocarboxylic acids or metal salts thereof and the polymeric binder is 5:95 to 95:5, preferably 20:80 to 80:20, more preferably 30:70 to 70:30.

[0113] The one or more monocarboxylic acids or salts thereof may be present in the waterborne antifouling coating composition comprising in an amount of 1.0 to 25 wt% relative to the total weight of the composition as a whole, preferably 1.0 to 15 wt%, more preferably 1.5 to 10 wt%, even more preferably 2.0 to 8.0 wt%

[0114] Other Binder components

[0115] In addition to the polymeric binder and monocarboxylic acids or salts thereof described above, additional binder(s) can be used to adjust the properties of the antifouling coating composition. Examples of binders that can be used include: polyethylene glycol) copolymers; saturated aliphatic polyesters, such as poly(lactic acid), poly(glycolic acid), poly(2- hydroxybutyric acid), poly(3 -hydroxybutyric acid), poly(4-hydroxy valeric acid), polycaprolactone and aliphatic polyester copolymer containing two or more of the units selected from the above mentioned units; and polymeric plasticizers from any of the polymer groups specified above.

[0116] Additional examples of other binder components that may be present in the antifouling coating composition of the invention include:

[0117] Polyurethane-based binder systems;

[0118] Hydrocarbon resins, such as hydrocarbon resin formed only from the polymerisation of at least one monomer selected from a C> aliphatic monomer, a C9 aromatic monomer, an indene coumarone monomer, or a terpene or mixtures thereof.

[0119] Additives

[0120] The antifouling coating composition of the present invention optionally comprises one or more additives. Examples of additives that may be present in the coating composition of the invention include, rheology modifiers, antifoaming agents, pH adjusting agents, dispersing agents, wetting agents, coalescing agents and plasticizers.

[0121] The coating composition of the invention preferably comprises a rheology modifier. A mixture of two or more rheology modifiers may be employed. The presence of a rheology modifier in the compositions of the invention advantageously improves the storage stability, the body of the coating composition and the application properties of the coating.

[0122] Examples of suitable rheology modifiers are polysaccharide rheology modifiers, associative rheology modifiers, clays, cellulosic rheology modifiers, fumed silica or a mixture thereof.

[0123] Exemplary polysaccharide rheology modifiers for use in the coating compositions include alginin, guar gum, locust bean gum and xanthan gum.

[0124] Exemplary clay rheology modifiers for use in the coating compositions of the invention include kaolin clay, smectite clay, illite clay, chlorite clay, synthetic clay or organically modified clay. Preferred clay rheology modifiers are synthetic clay or an organically modified clay.

[0125] Exemplary associative rheology modifiers for use in the coating compositions include non-ionic synthetic associative rheology modifiers (niSAT), hydrophobically modified alkoxylated urethanes such as hydrophobically modified ethoxylated urethanes (HEUR), hydrophobically modified alkali-swellable emulsions (HASE), and styrene-maleic anhydride terpolymers (SMAT). Acidic acrylate copolymers (cross-linked) of ethyl acrylate and methacrylic acid, and acrylic terpolymers (cross-linked) of ethyl acrylate, methacrylic acid, and non-ionic urethane surfactant monomer may also be used as associative rheology modifiers. Particularly preferred associative rheology modifiers present in the coating compositions of the invention are hydrophobically modified ethoxylated urethanes (HEUR).

[0126] Preferably rheology modifiers are present in the composition of the invention in an amount of 0 to 10 wt%, more preferably 0.1 to 6 wt% and still more preferably 0.1 to 2.0 wt%, relative to the total dry weight of the composition.

[0127] The coating composition of the present invention may comprise an antifoaming agent. Antifoaming agents are sometimes also referred to as foam control agents or defoamers. A wide range of antifoaming agents are commercially available, and may be used in the coating compositions of the invention. Representative examples of suitable antifoaming agents include organic siloxanes, polyethers, polyether-modified silicones, mineral oils and combinations thereof. Preferred coating compositions of the invention comprise 0 to 2.0 wt% antifoaming agent relative to the total weight of the coating composition. The coating composition of the present invention may comprise a pH adjusting agent such as ammonia, 2-aminopropanol, sodium hydroxide (NaOH), sodium carbonate (Na2COs) and sodium bicarbonate (NaHCCE).

[0128] Coalescing agents may optionally be included. In a waterborne paint composition, the applied wet product is inhomogeneous, as opposed to a solvent-borne composition which will be homogenous when applied. In order to form a film, the polymeric binder droplets or particles must coalesce. Coalescing agents aid this process in the water phase. Examples of suitable coalescing agents are ester alcohol, benzyl alcohol, propylene glycol monomethyl ether (PM), propylene glycol propyl ether (PnP), dipropylene glycol n-butyl ether (DPnB), propylene glycol phenyl ether (PPh), tripropylene glycol n-butyl ether (TPnB), ethylene glycol propyl ether (EP), ethylene glycol butyl ether (EB), diacetone alcohol (DAA) and dipropylene glycol methyl ether (DPM).

[0129] In order to improve or facilitate dispersion of the pigments, fillers and biocides it may be desirable to incorporate wetting / dispersing additives that are compatible with a waterborne coating composition. A wide range of dispersing agents is commercially available, and may be used in the coating compositions of the invention. Suitable dispersing agents include conventional anionic, cationic, non-ionic and amphoteric dispersing agents as well as combinations thereof.

[0130] Examples of suitable dispersing agents are polyalkylene glycol, polyacrylamide, polyethercarboxylate, polycarboxylates and sodium salts of acrylic polymers.

[0131] A plasticizer may be added to the coating composition of the present invention. Examples of suitable plasticizers are silicone oils (non-reactive polydimethylsiloxanes), chlorinated paraffins, phthalates, phosphate esters, sulphonamides, adipates, epoxidised vegetable oils and sucrose acetate isobutyrate.

[0132] Solvent

[0133] The antifouling coating composition of the present invention is a waterborne composition, i.e. one comprising water as the main solvent.

[0134] The antifouling coating composition of the present invention preferably comprises water as the main solvent.

[0135] Low amounts of organic co-solvents may be present such as ketones, alcohols, glycol ethers or other oxygen-containing solvents that are soluble or miscible with water. Preferably the coating composition comprises less than 10 wt% of an organic solvent, such as less than 7 wt%, more preferred less than 5 wt% or an organic solvent relative to the total weight of the composition as a whole. The antifouling coating composition may be organic solvent free.

[0136] The coating compositions comprise at least 5 wt% water, relative to the total weight of the composition as a whole. Preferably the coating compositions comprise at least 10 wt% water relative to the total weight of the composition as a whole. Preferably the compositions comprise 5 to 60 wt% water, more preferably 10 to 50 wt%, such as 15 to 40 wt%, relative to the total weight of the composition as a whole.

[0137] Biocides (iii)

[0138] The antifouling coating composition additionally comprises biocides, i.e. compounds capable of reducing or preventing settlement and / or growth of marine fouling on a surface. The terms antifouling agent, antifoulant, biocide and toxicant are used in the industry to describe known compounds that act to prevent marine fouling on a surface. The antifouling agents of the invention are marine antifouling agents. These compounds are present in a total amount of 8.0 wt% or less, relative to the total weight of the coating composition as a whole. Preferably, the coating composition comprises 7.5 wt% or less of biocides, relative to the total weight of the coating composition as a whole, more preferably 7.0 wt% or less, even more preferably 6.0 wt% or less, especially preferably 5.0 wt% or less.

[0139] Alternatively viewed, the ranges for the amount of biocides within the coating composition may be 0.2 to 8.0 wt%, 0.5 to 7.5 wt%, 1.0 to 7.0 wt% and 1.5 to 5.0 wt%, relative to the total weight of the coating composition as a whole, or any combination of said endpoints.

[0140] The total amount of biocides in the antifouling coating composition is preferably 1.0 to 20 wt%, more preferred 2.0 to 15 wt%, even more preferred 2.5 to 11 wt%, relative to the total dry weight of the coating composition.

[0141] The biocides must comprise tralopyril (iii-a) and one or more copper compounds having a copper content of at least 40 wt% relative to the formula weight of the copper compound (iii-b) as defined below. Tralopyril (iii-a)

[0142] As discussed above, 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)-lH-pyrrole-3- carbonitrile [tralopyril], having the structure below, must be present in the compositions of the invention:

[0143] Example of commercially available tralopyril include Econea® from Janssen PMP.

[0144] Optionally, the tralopyril may be encapsulated or adsorbed on an inert carrier or bonded to other materials for controlled release.

[0145] The amount of tralopyril (iii-a) present in the waterborne antifouling coating composition is preferably 5.0 wt% or less, such as 4.5 wt% or less, 4.0 wt% or less, 3.5 wt% or less, 3.0 wt% or less, 2.5 wt% of less, 2.0 wt% or less, 1.5 wt% or less or 1.0 wt% or less.

[0146] In all embodiments, it is preferred if tralopyril is present in an amount of 0.2 to 5.0 wt%, relative to the total weight of the composition, preferably 0.2 to 3.0 wt%, more preferably 0.3 to 2.0 wt%, even more preferably 0.4 to 1.5 wt%, such as 0.5 to 1.0 wt%.

[0147] In all embodiments, it is preferred if tralopyril is present in an amount of 0.2 to 6.5 wt%, relative to the total dry weight of the coating composition, preferably 0.3 to 6.0 wt%, more preferably 0.4 to 5.5 wt%, even more preferably 0.5 to 5.0 wt%.

[0148] Copper compound (iii-b)

[0149] The copper compound may be any suitable copper antifouling compound having a copper content of at least 40 wt%, relative to the total weight of the copper compound. Preferably, the copper compound has a copper content of at least 45 wt%, at least 50 wt%, at least 55 wt%, or at least 60 wt%, such as at least 70 wt% or at least 75 wt%, relative to the total weight of the copper compound. It will be understood that the copper content is calculated as the mass of copper atoms present in the chemical formula of the copper compound, excluding carrier materials. In the table below is a list of commonly used copper compounds and the calculated copper content in the compounds:

[0150] A single copper compound may be used, or alternatively a mixture of two or more copper compounds may be employed.

[0151] The copper compound may be present with carrier materials such as encapsulated copper compounds, copper glass, particles coated with copper compounds and porous particles with copper compounds. The wt% copper requirement refers to the amount of copper in the chemical copper compound and hence ignores the weight of any carrier.

[0152] Particularly preferred copper compounds are metallic copper, such as copper powder and copper flakes, copper(I) oxide, copper (II) sulfide and copper(I) thiocyanate. Copper(I) oxide is also referred to as cuprous oxide.

[0153] Preferably the copper compound is an inorganic copper compound such as metallic copper, copper(I) oxide and copper (II) sulfide, more preferred metallic copper powder and copper(I) oxide.

[0154] In one particularly preferred embodiment the copper compound is copper(I) oxide.

[0155] The copper(I) oxide material preferably has a typical particle diameter distribution of 0.1-70 pm and an average particle size (d50) of 1-25 pm. The copper(I) oxide material may contain a stabilizing agent to prevent surface oxidation and caking. Examples of commercially available copper(I) oxide include Nordox Cuprous Oxide Red Paint Grade, Nordox Cuprotech, Nordox XLT from Nordox AS, Cuprous oxide from Furukawa Chemicals Co., Ltd.; Red Copp 97N, Purple Copp, Lolo Tint 97N, Chemet CDC, Chemet LD from American Chemet Corporation; Cuprous Oxide Red from Spiess-Urania; Cuprous oxide Roast, Cuprous oxide Electrolytic from Taixing Smelting Plant Co., Ltd.

[0156] The amount of copper compound (iii-b) present in the waterborne antifouling coating composition is preferably 6.0 wt% or less, for example 5.0 wt% or less, such as 4.5 wt% or less, 4.0 wt% or less, 3.5 wt% or less, 3.0 wt% or less, 2.5 wt% or less, 2.0 wt% or less, 1.5 wt% or less or 1.0 wt% or less.

[0157] In all embodiments, it is preferred if the copper compound(s) is present in an amount of 0.2 to 6.0 wt%, relative to the total weight of the composition, preferably 0.2 to 5.0 wt%, more preferably 0.3 to 3.0 wt%, even more preferably 0.3 to 2.0 wt%, further preferred 0.5 to 1.0 wt%.

[0158] If a blend of copper compounds is present then each may be present in an amount of 0.1 to 6.0 wt%, relative to the total weight of the composition, preferably 0.2 to 5.0 wt%, more preferably 0.3 to 3.0 wt%, even more preferably 0.4 to 2.0 wt%, further preferred 0.5 to 1.0 wt%.

[0159] It is to be understood that the total amount of biocides in the coating composition of the invention cannot exceed 8.0 wt%. Suitable amounts and number of copper compounds can be selected accordingly.

[0160] More preferably the coating composition of the invention comprises 8.0 wt% or less of biocides, relative to the total weight of the coating composition as a whole, preferably 5.0 wt% or less.

[0161] In all embodiments, it is preferred if the copper compound is present in an amount of 0.2 to 9.9 wt%, relative to the total dry weight of the coating composition, preferably 0.2 to 9.0 wt%, more preferably 0.3 to 8.5 wt%, even more preferably 0.4 to 8.0 wt%, further preferred 0.5 to 7.5 wt%. It is also preferred if the total amount of biocides in the total dry weight of the coating composition of the invention does not exceed 11.0 wt%.

[0162] In those embodiments wherein more than one copper compound of the invention is present, it will be understood that these wt% ranges apply to the total amount of all copper compounds present. Note that if a copper compound is present that does not have 40 wt% copper then it is not a copper compound of the invention. Other biocides

[0163] In addition to these biocides, other antifouling compounds can be present. The antifouling agent may be inorganic, organometallic or organic. Suitable antifouling agents are commercially available.

[0164] Examples of organometallic marine antifouling agents include zinc pyrithione, copper pyrithione, copper di(ethyl 4,4,4-trifluoroacetoacetate), zinc bis(dimethyldithiocarbamate) [ziram] and zinc ethylenebis(dithiocarbamate) [zineb] and copper and zinc compounds as described in WO2021113564A1. It should be noted that copper pyrithione and copper di(ethyl 4,4,4-trifluoroacetoacetate) have a copper content of less than 40 wt% relative to formula weight and are therefore not included under the definition of a copper compound in the present invention.

[0165] Examples of organic marine antifouling agents include 2-( / c / 7-butylamino)-4- (cyclopropylamino)-6-(methylthio)-l,3,5-triazine [cybutryne], 4,5-dichloro-2-w-octyl-4- isothiazolin-3-one [DCOIT], 3 -(3, 4-di chlorophenyl)- 1,1 -dimethylurea [diuron] N- dichlorofluoromethylthio-7V',7V'-dimethyl-7V-phenylsulfamide [dichlofluanid], N- dichlorofluoromethylthio-7V',7V'-dimethyl-7V- / ?-tolylsulfamide [tolylfluanid], 7V-(2,4,6- trichlorophenyl)maleimide, triphenylborane pyridine [TPBP], 3-iodo-2-propynyl N- butylcarbamate [IPBC], 2,4,5,6-tetrachloroisophthalonitrile [chlorothalonil], / ?- ((diiodomethyl)sulphonyl)toluene and 4-[l-(2,3dimethylphenyl)ethyl]-lH-imidazole [medetomidine].

[0166] Other examples of marine antifouling agents may be tetraalkylphosphonium halogenides, macrocyclic lactones including avermectins and derivatives thereof such as ivermectine; furanone and lactam compounds such as 4-(4-chlorophenyl)-5-hydroxy-5- methyl-2(5H)-furanone and 4-(4-chlorophenyl)-5-methylene-lH-pyrrol-2(5H)-one; spinosyns and derivatives such as spinosad; capsaicin and derivatives such as phenylcapsaicin; and enzymes such as oxidase, proteolytically, hemicellulolytically, cellulolytically, lipolytically and amylolytically active enzymes.

[0167] Preferred biocides are zinc pyrithione, copper pyrithione, zinc ethylenebis(dithiocarbamate) [zineb], 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one [DCOIT], N-dichlorofluoromethylthio-N',N'-dimethyl-N-phenylsulfamide [dichlofluanid], 4-[l-(2,3- dimethylphenyl)ethyl]-lH-imidazole [medetomidine], copper di(ethyl 4,4,4- trifluoroacetoacetate) and phenylcapsaicin. A mixture of biocides can be used as known in the art as different biocides operate against different marine fouling organisms. Mixtures of antifouling agents are generally preferred.

[0168] If biocides other than (iii-a) and (iii-b) are used, these will still be counted towards the total biocide content and hence the 8.0 wt% maximum.

[0169] Some biocides may be encapsulated, adsorbed on an inert carrier or bonded to other materials for controlled release. The weight of any such carrier is not to be considered when determining the 8.0 wt% maximum.

[0170] Pigments, extenders and fillers

[0171] In addition to the polymeric binder, monocarboxylic acids or metal salts thereof, biocides and any of the optional components described above, the antifouling coating composition according to the present invention may optionally further comprise one or more components selected among inorganic or organic pigments, extenders and fillers.

[0172] The total amount of extenders, pigments and biocides present in the compositions of the invention is preferably at least 35 wt%, relative to the total weight of the coating composition as a whole. Having a total amount of extender and / or pigments and biocides of 35 wt% or more helps to achieve the appropriate self-polishing properties, coating film properties and sufficient antifouling performance.

[0173] Preferable total amounts of extenders, pigments and biocides are 35 to 65 wt%, more preferably 40 to 60 wt% and still more preferably 45 to 55 wt%, relative to the total weight of the composition.

[0174] Preferable total amounts of extenders, pigments and biocides are 40 to 90 wt%, more preferably 50 to 85 wt% and still more preferably 60 to 80 wt%, relative to the total dry weight of the coating composition.

[0175] The skilled person will appreciate that the extender and pigment content will vary depending on the particle size distribution, the particle shape, the surface morphology, the particle surface-resin affinity, the other components present and the end use of the coating composition.

[0176] Pigments are materials that provide colour to the coating composition. They are generally in the form of fine particles which are insoluble in the paint. The pigments may be inorganic pigments, organic pigments or a mixture thereof. Inorganic pigments are preferred. Examples of inorganic pigments include titanium dioxide, red iron oxide, yellow iron oxide, black iron oxide, zinc sulfide, lithopone and graphite. Examples of organic pigments include carbon black, phthalocyanine blue, phthalocyanine green, napthol red and diketopyrrolopyrrole red. Pigments may be surface treated. A variety of inorganic or organic surface treatments are used, e.g. to improved storage stability and to enhance pigment performance, such as rheological properties and dispersibility in the coating composition. As an example, titanium dioxide may be surface treated with a silicon compound, a zirconium compound, an aluminum compound and / or a zinc compound.

[0177] Extenders are materials added to paint to adjust or improve their properties. These materials have typically low colour strength and hence are distinguished from pigments. Extenders are typically in granular or powder form and are insoluble in the paint. The extenders may be inorganic or organic materials. Inorganic extenders are preferred. Inorganic extenders may be natural minerals or synthetic materials.

[0178] Examples of extenders and fillers are minerals such as dolomite, plastorite, calcite, quartz, baryte, magnesite, aragonite, silica, nepheline syenite, wollastonite, talc, chlorite, mica, kaolin, pyrophyllite, perlite, silica and feldspar; synthetic inorganic compounds such as calcium carbonate, magnesium carbonate, barium sulfate, calcium silicate, zinc phosphate and silica (colloidal, precipitated, fumed, etc.); polymeric and inorganic microspheres such as uncoated or coated hollow and solid glass beads, uncoated or coated hollow and solid ceramic beads, porous and compact beads of polymeric materials.

[0179] Preferably the total amount of extender, filler and / or pigment present in the antifouling coating compositions of the invention is 25 to 65 wt%, more preferably 30 to 60 wt% and still more preferably 40 to 50 wt%, relative to the total weight of the composition.

[0180] Preferably the total amount of extender, filler and / or pigment present in the compositions of the invention is 30 to 85 wt%, preferably 40 to 80 wt%, more preferably 50 to 75 wt% of the total dry weight of the coating composition

[0181] The skilled person will appreciate that the extender, filler and pigment content will vary depending on the particle size distribution, the particle shape, the surface morphology, the particle surface-resin affinity, the other components present and the end use of the antifouling coating composition.

[0182] Examples of reinforcing fillers are flakes and fibres. Fibres include natural and synthetic inorganic fibres and natural and synthetic organic fibres e.g. as described in WO 00 / 77102. Representative examples of fibres include mineral-glass fibres, wollastonite fibres, montmorillonite fibres, tobermorite fibres, atapulgite fibres, calcined bauxite fibres, volcanic rock fibres, bauxite fibres, rockwool fibres, and processed mineral fibres from mineral wool. Preferably, the fibres have an average length of 25 to 2,000 gm and an average thickness of 1 to 50 gm with a ratio between the average length and the average thickness of at least 5. Preferably reinforcing fillers are present in the compositions of the invention in an amount of 0-20 wt%, more preferably 0.5-15 wt% and still more preferably 1- 10 wt%, relative to the total weight of the composition.

[0183] Examples of flaky fillers are mica, glass flakes and micronized iron oxide (MiO).

[0184] Antifouling coating composition properties

[0185] The antifouling coating composition of the invention should preferably have solids content above 35 vol%, e.g. above 40 vol%, such as above 42 vol%. Values up to 65 %vol. solids are possible.

[0186] The antifouling coating composition of the invention should preferably have solids content of 50 to 90 wt% such as 60 to 80 wt% relative to the total weight of the composition as a whole.

[0187] More preferably the antifouling coating composition should have a content of volatile organic compounds (VOC) of less than 200 g / L, preferably less than 150 g / L, more preferably less than 100 g / L, e.g. less than 70 g / L. VOC content can be calculated as described in e.g. ASTM D5201 - 05a(2020) or IED 2010 / 75ZEU or measured, e.g. as described in US EPA Method 24 or ISO 11890-2.

[0188] The antifouling coating composition of the invention ideally has a pigment volume concentration (PVC) of less than 80%, more preferably less than 60%, further preferred less than 55%. Preferably the PVC of the coating composition of the invention is 30 to 60%, more preferably 35 to 55%. Pigment Volume Concentration (PVC) is defined as the ratio of pigment volume to the total dry film volume.

[0189] Applications

[0190] The antifouling coating composition of the invention can be applied to a whole or part of any object surface which is subject to fouling. The surface may be permanently or intermittently underwater (e.g. through tide movement, different cargo loading or swell). The object surface will typically be the hull of a vessel or surface of a fixed marine object such as an oil platform or buoy. The surface of the substrate may be the "native" surface (e.g. the steel surface) or a surface which already has an organic primer layer coated thereon. Application of the coating composition can be accomplished by any convenient means, e.g. via painting (e.g. with brush or roller) or spraying the coating onto the object. Typically, the surface will need to be separated from the seawater to allow coating. The application of the coating can be achieved as conventionally known in the art.

[0191] When applying the antifouling coating to an object (e.g. a ship hull) the surface of the object is preferably not protected solely by a single coat of antifouling coating composition. Depending on the nature of the surface, the antifouling coating can be applied directly to an existing coating system. Such a coating system may comprise several layers of paint of different generic types (e.g. epoxy, polyester, vinyl or acrylic or mixtures thereof). Starting with an uncoated surface (e.g. steel, aluminium, plastic, composite, glass fiber or carbon fiber) the full coating system will typically comprise one or two layers of a primer such as an anticorrosive coating (e.g. curable epoxy coating or curable modified epoxy coating), one layer of tie-coat (e.g. curable modified epoxy coating or physical drying vinyl coating) and one or two layers of antifouling paint. In exceptional cases further layers of antifouling paint may be applied. If the surface is a clean and intact antifouling coating from a previous application, the new antifouling paint can be applied directly, typically as one or two coats with more in exceptional cases. When two or more coats of antifouling coating composition is applied, the different coats can be antifouling coatings of different compositions. If different compositions are used in consecutive layers, the difference may e.g. be in the type and / or amount of biocide and binder, binder composition and / or polishing rate.

[0192] In certain cases, for example for outfitting applications, it is preferred if antifouling coating compositions having different polishing rates are used in different coating layers. It is then preferred if the outermost layer has a higher polishing rate than the subsequent layers. The coating formed from the coating composition of the invention can also be cleaned by for example robots, remotely operated vehicles (RO Vs) or manually operated equipment. The cleaning can be reactive or proactive. The underwater cleaning can for example be made using mechanical means (such as brushes, squeegee), high pressure water, UV light, laser or ultrasound. Robots used for underwater cleaning is for example described in WO20 19 / 170888, W02020 / 207791 and W02020 / 207792. Cleaning settings that can be used when using brushes are for example described in WO2021 / 180588.

[0193] The coating composition of the present invention may be applied on anticorrosive primers, tie-coat and antifouling coating films prepared from waterborne, solvent-borne and solvent free coating compositions. The invention will now be defined with reference to the following non-limiting examples.

[0194] Examples

[0195] Unless stated otherwise, amounts given are in parts by weight.

[0196] Materials and methods Table 1 - List of materials Calculation of the volatile organic compound (VOC) content of the antifouling coating composition

[0197] The volatile organic compound (VOC) content of the antifouling coating composition was calculated in accordance with ASTM D5201-01.

[0198] Testing of antifouling performance

[0199] Polyvinyl chloride (PVC) panels (20 cm x 30 cm) were used for the test. The panels were coated with a first coat of a commercial tie-coat (Safeguard Plus, manufactured by Chokwang Jotun Ltd., Korea) using airless spray and a second coat of a commercial antifouling paint (SeaQuantum Ultra III, manufactured by Jotun Paints (Europe) Ltd.). The curing / drying time and film thicknesses of the first coat and the second coat were within the recommended intervals in the technical data sheets for the products.

[0200] The antifouling coating compositions of the examples were applied directly to the precoated PVC panels as a last coat using a film applicator with a 400 pm gap size. The test areas of the applied coating films were approx. 6.5 cm x 25 cm. The edges of the panels were sealed with a commercial antifouling product.

[0201] The panels were exposed on raft in Singapore where the panels were submerged 0.5 to 1.5 m below the sea surface. The panels were evaluated by visual inspection and rated according to the scale below. Macroalgae, such as seaweed, and animal fouling, such as barnacles, tubeworms, mussels, sponges and hydroids, were included in the rating. Microfouling organisms, such as biofilm or slime, which can easily be removed by hand, is not included in the rating. Edge effects were excluded from the evaluation. A rating of 0 or 1 is considered good antifouling properties.

[0202] Table 2 - Rating scale for degree of fouling Accelerated cracking testing of coating films in seawater (SW) - Immersion SW

[0203] Poly(vinyl chloride) (PVC) panels were coated with a commercial tie-coat (Safeguard Plus, manufactured by Chokwang Jotun Ltd., Korea) using airless spray. The antifouling coatings were applied on the panels using a film applicator with gap size of 800 pm. The panels were dried for approximately one month at room temperature before immersion in seawater (SW) at 40°C. At regular intervals, the panels were taken out and evaluated. The panels were evaluated for cracking visually and under 10 x magnifications upon drying at room temperature for 24 hours and again after drying at 52°C for 24 hours. The panels were then re-immersed. The rating after drying at 52°C are reported in the tables with the paint examples.

[0204] The panels were rated as follows: 0 - No cracks

[0205] 1 - Very few cracks

[0206] 2 - Moderate number of cracks

[0207] 3 - Considerable number of cracks

[0208] 4 - Dense cracking

[0209] Accelerated blistering testing of coating films in freshwater (FW) - Immersion FW Poly(vinyl chloride) (PVC) panels were coated with a commercial tie-coat (Safeguard Plus, manufactured by Chokwang Jotun Ltd., Korea) using airless spray. The antifouling coatings were applied on the panels using a film applicator with gap size of 800 pm. The panels were dried for approximately one month at room temperature before immersion in freshwater (FW) at 30°C. At regular intervals, the panels were taken out and evaluated. The panels were evaluated for blistering visually at room temperature. The panels were then reimmersed. The ratings are reported in the tables with the paint examples.

[0210] The panels were rated as follows: 0 - No blisters

[0211] 1 - Very few blisters

[0212] 2 - Moderate number of blisters

[0213] 3 - Considerable number of blisters 4 - Dense blistering

[0214] General procedure for preparation of antifouling coating compositions The components were mixed in the proportions given in the below Tables 3 to 9. The order of mixing the ingredients and preparation of pre-mix of selected ingredients were done in accordance with the raw material suppliers’ guidelines. Pigments, extenders and fillers, biocides, additives and water were mixed and grinded using a high-speed mixer until the mill base had fineness of grind below 40 pm. Then the binder ingredients and rheology modifiers were added to the mixture and mixed using a vibrational shaker.

[0215] Table 3 - Summary of Examples with tralopyril and cuprous oxide

[0216] Table 4 - Summary of Examples with tralopyril and copper compounds

[0217] Table 5 - Summary of Examples with tralopyril and cuprous oxide with variations in extenders

[0218] Table 6 - Summary of Examples with tralopyril and cuprous oxide combined with various biocides

[0219]

[0220] Table 7 - Summary of Comparative Examples (CoEx) without Cu-compound

[0221]

[0222] Table 8 - Summary of Comparative Examples (CoEx) without tralopyril or with low levels of tralopyril

[0223]

[0224] Table 9 - Summary of Examples and Comparative Examples with varying pigmentation and binder content levels

[0225]

[0226] N / A: Coating films cracked upon drying before they could be exposed.

[0227] Observations from the experiments summarised in Table 3

[0228] Inventive Example 1 shows that 1 wt% of cuprous oxide and 1 wt% of tralopyril will give a good antifouling performance

[0229] Inventive Example 2 shows that 0.5 wt% of each of the two biocides will still give sufficient antifouling performance

[0230] Inventive Example 1 contains 1.0 wt% cuprous oxide, 1.0 wt% tralopyril and 1.0 wt% copper pyrithione; it shows improved antifouling performance compared to comparative example CoEx-10 (Table 8) which has 1.0 wt% cuprous oxide and 1.0 wt% copper pyrithione but lacks tralopyril and comparative example CoEx-4 (Table 7) which has 1.0 wt% tralopyril and 1.0 wt% copper pyrithione but lack cuprous oxide Inventive Example 1 also shows improved antifouling performance compared to comparative example CoExl2 (Table 8) which has 2.0 wt% cuprous oxide and 1.0 wt% copper pyrithione but lacks tralopyril

[0231] All inventive examples show excellent mechanical properties when immersed in fresh and salt water; no defects such as blistering or cracking observed after 6 months as shown by the Immersion FW and Immersion SW test results

[0232] Observations from the experiments summarised in Table 4

[0233] Inventive examples show combination of tralopyril and copper powder (Ex-7 and Ex- 11), combination of tralopyril with copper sulfide (Ex- 10 and Ex- 12), as well as combinations of tralopyril with more than one copper compound. Table 4 includes additional biocides such as medetomidine and zineb in addition to tralopyril and a copper compound

[0234] Observations from the experiments summarised in Table 5

[0235] Inventive examples where variation in the extenders are shown, such as increase or decrease in zinc oxide and zinc phosphate levels Observations from the experiments summarised in Table 6

[0236] Inventive examples show formulations with tralopyril and cuprous oxide combined with different biocides such as zineb, medetomidine and DCOIT (either as the free biocide in xylene or encapsulated)

[0237] Observations from the experiments summarised in Table 7

[0238] Comparative example CoEx-1 has no biocides and does not withstand the fouling pressure in Singapore

[0239] Comparative examples CoEx-2 and CoEx-3 do not contain tralopyril or a copper compound and do not show sufficient antifouling performance

[0240] Comparative examples CoEx-4 to CoEx-8 do not include a copper compound as defined hereinbefore and do not show sufficient antifouling performance, neither 1 wt% nor 2 wt% tralopyril are effective without a copper compound present Combination with DCOIT or Zineb does not protect efficiently against animal fouling either

[0241] Observations from the experiments summarised in Table 8

[0242] Comparative examples with cuprous oxide without tralopyril

[0243] 3 wt% cuprous oxide is not sufficient to obtain the desired antifouling performance without tralopyril present (CoEx-14)

[0244] CoEx-15 includes tralopyril and cuprous oxide, however 0.2 wt% of each biocide is not sufficient to protect against animal fouling in Singapore

[0245] Observations from the experiments summarised in Table 9

[0246] CoEx-18 and CoEx-20 show high pigmentation levels which show decreased antifouling performance and reduced mechanical properties when immersed in fresh and salt water; both CoEx-18 and CoEx-20 show blistering and cracking when immersed in fresh and salt water, respectively

[0247] CoEx-19 and CoEx-20 lack rosin / monocarboxylic acid (ii) as part of the binder matrix and show poor antifouling performance after 5 months

[0248] CoEx-22 show a similar solvent-borne formulation, it shows poor antifouling performance, decreased mechanical properties when immersed in fresh and salt water and it has high VOC compared to the inventive examples Inventive example Ex-28 is a repeat of Inventive example Ex-1 exposed at a later timepoint (together with the Inventive example Ex-29 and Comparative examples CoEx-23 to CoEx-25); Ex-28 shows good antifouling performance

[0249] Comparative examples CoEx-23 and CoEx-24 have low pigmentation levels (PVC<30) which show poor antifouling performance

[0250] Inventive example Ex-29 with PVC>30 shows good antifouling performance Comparative example CoEx-25 was made without any polymeric binder (i) which cracked heavily upon drying before the panels could be exposed to Raft and immersion testing.

Claims

1. Claims1. A waterborne antifouling coating composition comprising: i) a polymeric binder comprising a structural unit derived from an ethylenically unsaturated monomer; ii) one or more monocarboxylic acids or metal salts thereof; and iii) less than 8.0 wt%, relative to the total weight of the composition as a whole, of biocides, wherein said biocides comprise: a. tralopyril; and b. one or more copper compounds having a copper content of at least 40 wt%, relative to the formula weight of the copper compound; wherein the coating composition comprises at least 5 wt% water relative to the total weight of the composition as a whole.

2. The waterborne antifouling coating composition as claimed in claim 1, wherein said composition has a volatile organic compound (VOC) content of less than 200 g / L, preferably less than 150 g / L, more preferably less than 100 g / L, even more preferably less than 70 g / L.

3. The waterborne antifouling coating composition as claimed in claim 1 or 2, wherein said composition further comprises pigments and / or extenders, preferably wherein the total amount of pigments, extenders and biocides is 35 to 65 wt%, more preferably 40 to 60 wt% and still more preferably 45 to 55 wt%, relative to the total weight of the composition.

4. The waterborne antifouling coating composition as claimed in any of claims 1 to 3, wherein said composition has a pigment volume concentration (PVC) of less than 80%, preferably less than 60 wt%, more preferably less than 55 wt%.

5. The waterborne antifouling coating composition as claimed in any of claims 1 to 4, wherein the polymeric binder comprises (meth)acrylic acid and / or (meth)acrylic acid ester monomers, preferably wherein the polymeric binder comprises at least 15 wt%, relative to the total weight of the polymeric binder of (meth)acrylic acid and / or(meth)acrylic acid ester monomers.

6. The waterborne antifouling coating composition as claimed in any of claims 1 to 5, wherein the composition comprises 1.0 to 30 wt% of the polymeric binder, relative to the total weight of the composition as a whole, preferably 2.0 to 25 wt%, more preferably 5.0 to 15 wt%.

7. The waterborne antifouling coating composition as claimed in any of claims 1 to 6, wherein the one or more monocarboxylic acids or metal salts thereof is rosin, modified rosin or metal salts thereof, especially gum rosin, hydrogenated gum rosin, copper salt of gum rosin, zinc salt of gum rosin, copper salt of hydrogenated gum rosin, zinc salt of hydrogenated gum rosin and mixtures thereof.

8. The waterborne antifouling coating composition as claimed in any of claims 1 to 7, wherein the composition comprises the one or more monocarboxylic acids of metal salts thereof in an amount of 1.0 to 25 wt% relative to the total weight of the composition as a whole, preferably 1.0 to 15 wt%, more preferably 1.5 to 10 wt%, even more preferably 2.0 to 8.0 wt%9. The waterborne antifouling coating composition as claimed in any of claims 1 to 8, wherein the composition comprises less than 7.5 wt%, relative to the total weight of the composition as a whole, of the biocides, preferably less than 7.0 wt%, even more preferably less than 6.0 wt%.

10. The waterborne antifouling coating composition as claimed in any of claims 1 to 9, wherein tralopyril is present in an amount of 0.2 to 5.0 wt%, relative to the total weight of the composition, preferably 0.2 to 3.0 wt%, more preferably 0.3 to 2.0 wt%, even more preferably 0.4 to 1.5 wt%, such as 0.5 to 1.0 wt%.

11. The waterborne antifouling coating composition as claimed in any of claims 1 to 10, wherein the one or more copper compounds having a copper content of at least 40 wt%, relative to the formula weight of the copper compound, are present in an amount of 0.2 to 6.0 wt%, relative to the total weight of the composition, preferably 0.2 to 5.0 wt%, more preferably 0.3 to 3.0 wt%, even more preferably 0.4 to 2.0 wt%, furtherpreferred 0.5 to 1.0 wt%.

12. The waterborne antifouling coating composition as claimed in any of claims 1 to 11, wherein the one or more copper compounds (b) comprises at least one of cuprous oxide, copper powder and copper(II) sulfide, preferably cuprous oxide.

13. The waterborne antifouling coating composition as claimed in any of claims 1 to 12, wherein the coating composition comprises at least 7 wt% water relative to the total weight of the composition as a whole, preferably at least 9 wt%, more preferably at least 10 wt%.

14. A process for applying a waterborne antifouling coating composition to a substrate comprising applying, e.g. by spraying, a waterborne antifouling coating composition as defined in any of claims 1 to 13 to a substrate and allowing the coating composition to dry.

15. A substrate coated with a waterborne antifouling coating as defined in any of claims 1 to 13, wherein said coating composition has been allowed to dry, preferably wherein the substrate is the surface of a marine structure, more preferably a marine structure which is submerged when in use.

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