Compositions and methods for antifouling protection

Abstract

In general, the present disclosure is generally directed to an antifouling composition. The antifouling composition may include a copper biocide and a synthetic polymer. Beneficially, the antifouling composition may be incorporated around an antifouling paint having less than about 1% by weight of non-encapsulated copper biocide in the antifouling paint.

Description

Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)COMPOSITIONS AND METHODS FOR ANTIFOULING PROTECTIONRELATED APPLICATIONS

[0001] The present application is based on and claims priority to U.S. Provisional Patent application Serial No. 63 / 727,869, filed on December 04, 2024, which is incorporated herein by reference.BACKGROUND

[0002] Ships, aquaculture fishnets, underwater structures, and underwater equipment are frequently targeted by marine organisms, such as barnacles, bryozoans, hydroids, mussels, algae, and the like. Such organisms can grow, multiply, and eventually cause significant problems. For example, in the case of a ship’s hull, growth of marine organisms on the hull can increase frictional resistance between the hull and water, thus increasing fuel consumption and reducing the speed of the ship. Ship hulls need to be protected against the growth of marine organisms in order to keep the hulls clean and smooth for maximum fuel efficiency. Transporting marine organisms from one part of the world to another can also introduce foreign organisms and disrupt a local ecosystem. Thus, adequate protection against marine biofouling is advantageous for underwater parts.

[0003] Antifouling paints are frequently added to underwater parts to limit marine biofouling. The binder systems used for such antifouling paints generally include an erodible binder. Erosion of the paint film aids in preventing fouling by releasing biocidal agents from the coating over time thus impeding attachment of marine organisms. There are two main types of erodible antifouling coatings, self-polishing and ablative.

[0004] Most commercially available antifouling paints contain a high metal content due to the high concentration of cuprous oxide (CU2O) used as the biocidal agent, typically about forty percent by weight, which is required for appropriate antifouling protection. Leaching from antifouling paints can contribute to elevated copper levels in water, sediments, and surrounding environments. Artificial high copper levels may have a significant ecological impact. While cuprous oxide is widely used as antifouling agent in antifouling paints, antifouling paints can also contain additional biocidal agents because cuprous oxide alone is generally only effective against hard fouling organisms, like barnacles.

[0005] Therefore, there is a need for ecologically and economically improved antifouling paints with reduced biocidal agent content. Reducing copper content would be particularly useful.Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)SUMMARY

[0006] In general, the present disclosure is generally directed to an antifouling composition. The antifouling composition may include a plurality of particles that comprise copper biocide and a synthetic polymer that encapsulates each of the plurality of particles. Beneficially, the total biocide content of the antifouling composition may include less than about 1% of non-encapsulated copper biocide. Further, the antifouling composition disclosed herein may be included in an antifouling paint.

[0007] Also, the present disclosure is directed to a microcapsule. The microcapsule, for instance, may include an encapsulated material with a copper biocide and a capsule wall with a synthetic polymer. The amount of non-encapsulated copper biocide around the microcapsule, for instance, may be less than about 1 wt.% of the total biocide content in the antifouling composition.

[0008] Also, the present disclosure is directed to an antifouling paint. The antifouling paint, for instance, may include a plurality of microcapsules containing an antifouling composition disclosed herein.

[0009] Other features and aspects of the present disclosure are discussed in greater detail below.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A full and enabling disclosure of the present disclosure is set forth more particularly in the remainder of the specification, including reference to the accompanying figure, in which:

[0011] Figure 1 depicts release rates of a copper biocide (e.g., copper pyrithione (CuPT) from the controlled-release CuPT microcapsules in Xylene.

[0012] Figure 2 depicts the controlled release of CuPT after 30 minutes of leaching into sea water.

[0013] Figure 3 depicts the controlled release of CuPT after 180 minutes of leaching into sea water.

[0014] Figure 4 depicts the controlled release of cuprous oxide (CinO) after 360 minutes of leaching into sea water.

[0015] Figure 5 depicts Scanning Electron Microscopy (SEM) images of a Focused Ion Beam (FIB) cross-section of a particle agglomerate.Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)

[0016] Figure 6 depicts the thickness of a fringe between the Au layer and the particles of the particle agglomerate depicted in Figure 5.

[0017] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.DETAILED DESCRIPTION

[0018] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0019] The present disclosure is generally directed to an antifouling composition. The antifouling composition may include a copper biocide and a synthetic polymer. Beneficially, the antifouling composition may be a plurality of microcapsules having less than about 1% by weight of non-encapsulated copper biocide. For instance, the copper biocide may be formed as a plurality of microparticles, and the plurality of microparticles may be encapsulated by the synthetic polymer. Further, the antifouling composition disclosed herein may be included in an antifouling paint. The antifouling paint may inhibit the fouling of surfaces of underwater objects, such as ship hulls or any other marine structures. Surprisingly, the combination of a copper biocide and a synthetic polymer may improve the efficacy of known biocidal agents. For instance, non-encapsulated copper biocide may be significantly reduced and / or eliminated from the antifouling paint without compromising on the biocidal protection of the antifouling coating. Moreover, the synthetic polymer in combination with the copper biocide significantly enhances the antifouling efficacy of the biocidal agent in the antifouling paint against the settling of marine organisms, such as barnacles, bryozoans, hydroids, mussels, algae, and the like. It is readily understood that a bioavailable or bioactive biocide needs to be present / available in water in dissolved form. As such, encapsulation of the almost water insoluble copper biocides (such as copper pyrithione and cuprous oxide) - further reducing the bioavailability of the active substances - seems counterintuitive with regard to a high antifouling efficacy required for marine coatings. Surprisingly, encapsulation of the copper biocide disclosed herein can allow for the formulation of antifouling paints that include lower amounts of the copper biocide, ultimately mitigating at least some of the environmental concerns associated with such products.

[0020] In some example embodiments, the antifouling composition may include a copper biocide. The copper biocide may be incorporated into the antifouling composition in the formAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) of inorganic copper salts, such as carbonate, bicarbonate, sulfate, nitrate, chloride, hydroxide, borate, fluoride or oxide.

[0021] In one example embodiment, for instance, the copper biocide may include, but is not limited to, copper hydroxide, copper(I)oxide, copper(II)oxide, copper carbonate, basic copper carbonate, copper sulfate, basic copper sulfate, copper acetate, copper borate, copper citrate, copper chloride, copper hydroxide, copper oxychloride, copper oleate, copper silicate, copper 8-hydroxy quinolate, copper dimethyldithiocarbamate, copper naphthenate, cufraneb or tricopper dichloride dimethyldithiocarbamate, copper salts of fatty and rosin acids, copper ethylenediaminetetraacetate, copper thiocyanate, or a combination thereof.

[0022] In another example embodiment, for instance, the copper biocide may be in the form of copper-complex such as N-nitroso-N-cyclohexyl-hydroxylamine-copper (copper- HDO) or copper pyrithione (bis(2-pyridylthio)copper 1,1 '-dioxide), copper ethylenediamine complex, copper triethanolamine complex, copper diammonia diacetate complex, or copper ethanolamine complex.

[0023] In another example embodiment, for instance, the copper biocide may be in the form of a copper (II) ion. For instance, forms of copper (II) may include, but is not limited to, basic copper chloride, basic copper carbonate (Cu2(OH)2COs), copper (II) acetate, copper ammonium carbonate complex, copper (II) hydroxide, copper (II) oxide, copper oxychloride, copper oxychloride sulfate, copper ammonium complex, chelates of copper citrate, chelates of copper gluconate, copper (II) sulphate pentahydrate, or a combination thereof.

[0024] In one example embodiment the copper biocide may include, but is not limited to, copper pyrithione, cuprous oxide, copper (I) thiocyanate, or a combination thereof. For instance, in one example embodiment, the copper biocide may be copper pyrithione. In another example embodiment, the copper biocide may be cuprous oxide. In yet another example embodiment, the copper biocide may be copper (I) thiocyanate.

[0025] In one example embodiment, the microencapsulated copper biocide may be in the form of a copper compound having a particle size of from about 0.01 microns to about 50 microns, such as from about 0. 1 microns to about 40 microns, such as from about 1 microns to about 30 microns, such as from about 5 microns to about 25 microns, such as from about 10 microns to about 20 microns, or any range therebetween.

[0026] In one example embodiment, notwithstanding the type or amount of copper biocide(s) selected, the copper biocide may be present in solid, micronized form or dispersed in a liquid carrier phase. For instance, the copper particles may have a particle size D50 of about 25 microns or less, such as about 10 microns or less, such as about 6 microns or less,Attorney Docket No.: ARXMP-400-PCT (LP3752PC00) such as about 5 microns or less, such as about 4 microns or less, such as about 3 microns or less, such as about 2 microns or less, such as about 1 micron or less. In one example embodiment, copper particles in the antifouling composition may have a particle size D50 of about 5 microns or less. In another example embodiment, copper particles in the antifouling composition may have a particle size D50 of about 3 microns or less.

[0027] Notwithstanding the form of the copper biocide, the copper biocide may be present in the antifouling composition from about 10% to about 95% by weight of the antifouling composition, such as from about 20% to about 95%, such as from about 25% to about 95%, such as from about 30% to about 95%, such as from about 40% to about 95%, such as from about 55% to about 90%, such as from about 60% to about 85%, such as from about 65% to about 80% by weight of the antifouling composition, or any ranges or values there between. In one example embodiment, the copper biocide may be present in the antifouling composition from about 50% to about 95% by weight of the antifouling composition. In another example embodiment, the copper biocide may be present in the antifouling composition from about 55% to about 90% by weight of the antifouling composition. In yet another example embodiment, the copper biocide may be present in the antifouling composition from about 60% to about 85% by weight of the antifouling composition.

[0028] In some example embodiments, the antifouling composition may include a synthetic polymer. For instance, the synthetic polymer may be selected from a group consisting of a melamine formaldehyde polymer, a melamine urea formaldehyde polymer, a polyurea polymer, a polyurethane polymer, a urea formaldehyde polymer, a polyvinyl alcohol, a polyacrylate, a polymethylmethacrylate, a polystyrene, a polyvinylpyrrolidone, or a synthetic copolymer or a combination thereof. In one example embodiment, the synthetic polymer may be a melamine formaldehyde polymer. In one example embodiment, the synthetic polymer may be a melamine urea formaldehyde polymer. In one example embodiment, the synthetic polymer may be a polyurea polymer. In one example embodiment, the synthetic polymer may be a polyurethane polymer. In one example embodiment, the synthetic polymer may be a urea formaldehyde polymer. In one example embodiment, the synthetic polymer may be a polyvinyl alcohol. In one example embodiment, the synthetic polymer may be a polyacrylate. In one example embodiment, the synthetic polymer may be a polymethylmethacrylate. In one example embodiment, the synthetic polymer may be a polystyrene polymer. In one example embodiment, the synthetic polymer may be a polyvinylpyrrolidone.Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)

[0029] In some example embodiments, the additive composition disclosed herein may include a combination of the copper biocide and the synthetic polymer. It is understood that the relative amounts of the copper biocide and the synthetic polymer may vary depending on, e.g., the nature of the copper biocide and the nature of the synthetic polymer. Beneficially, however, the weight ratio of the copper biocide and the synthetic polymer may be from about 25: 1 to about 1:25, such as from about 20: 1 to about 1:20, such as from about 15: 1 to about 1 : 15, such as from about 10: 1 to about 1 : 10, such as from about 5 : 1 to about 1:5, such as from about 3: 1 to about 1 :3, such as from about 2:1 to about 1 :2, or any range therebetween. In one example embodiment, the weight ratio of the copper biocide and the synthetic polymer may be from about 25: 1 to about 1:25. In another example embodiment, the weight ratio of the copper biocide and the synthetic polymer may be from about 15: 1 to about 1: 15. In yet another example embodiment, the weight ratio of the copper biocide and the synthetic polymer may be from about 10: 1 to about 1: 10. Such weight ratios have been advantageously found to increase an efficacy of the copper biocide when the antifouling compositions disclosed herein are incorporated into an antifouling paint, which allows for lower amounts of the copper biocide as relative to antifouhng paints without the antifouling compositions disclosed herein.

[0030] Example aspects of the present disclosure further provide for the use of the antifouling compositions for the inhibition of marine biofouling on a solid surface. The solid surface may be any solid surface of underwater objects, such as ships, an aquaculture fishnet, an underwater structure and equipment, a tank, an offshore construction, a pipe, a net, a pier, a pile, a pillar, or the like.

[0031] In some example embodiments, advantageously, the antifouling compositions disclosed herein may be in the form of a microcapsule, allowing the controlled release of the copper biocide, e.g. by releasing the copper biocide component from an antifouling coating over time as is the case with self-polishing or ablative coatings.

[0032] In some example embodiments, the microcapsule may be useful in controlling the release of the antifouhng composition disclosed herein in an antifouhng paint. For instance, the microcapsule may include, but is not limited to, a core containing an encapsulated active material and a capsule wall that encapsulates the active material.

[0033] In one example embodiment, the core of the microcapsule may define an outer peripheral surface of the microcapsule. For instance, the copper biocide may be present in the microcapsule at a relatively high loading, such from about 10% to about 95% by weight of the microcapsule, such as from about 20% to about 95%, such as from about 25% to aboutAttorney Docket No.: ARXMP-400-PCT (LP3752PC00)95%, such as from about 30% to about 95%, such as from about 40% to about 95%, such as from about 55% to about 90%, such as from about 60% to about 85%, such as from about 65% to about 80% by weight of the microcapsule, or any ranges or values there between. In one example embodiment, the copper biocide may be present in the microcapsule from about 50% to about 95% by weight of the microcapsule. In another example embodiment, the copper biocide may be present in the microcapsule from about 55% to about 90% by weight of the microcapsule. In yet another example embodiment, the copper biocide may be present in the microcapsule from about 60% to about 85% by weight of the microcapsule.

[0034] As described above, for instance, the copper biocide of the microcapsule may include, but is not limited to, copper hydroxide, copper(I)oxide, copper(II)oxide, copper carbonate, basic copper carbonate, copper sulfate, basic copper sulfate, copper acetate, copper borate, copper citrate, copper chloride, copper hydroxide, copper oxychloride, copper oleate, copper silicate, copper 8-hydroxy quinolate, copper dimethyldithiocarbamate, copper naphthenate, cufraneb or tricopper di chloride dimethyldithiocarbamate, copper salts of fatty7and rosin acids, copper ethylenediaminetetraacetate, copper thiocyanate, or a combination thereof.

[0035] In one example embodiment, the copper biocide of the microcapsule may include, but is not limited to, copper pyrithione, cuprous oxide, copper (I) thiocyanate, or a combination thereof. For instance, in one example embodiment, the copper biocide may be copper pyrithione. In another example embodiment, the copper biocide may be cuprous oxide. In yet another example embodiment, the copper biocide may be copper (I) thiocyanate.

[0036] In one example embodiment, the microcapsule may include a capsule wall that encapsulates the active material. For instance, the capsule wall may be made up of a synthetic polymer encapsulating the copper biocide. The synthetic polymer may be at least partially crosslinked in the microcapsule. Surprisingly, prematurely interrupting the cross-linking (curing) process of the wall resin which leaves a certain percentage of hydroxyl groups unreacted leading to wider and - due to the OH groups - more hydrophilic pores, fosters the water-based diffusion / migration of the biocides to the paint surface.

[0037] As described above, for instance, the synthetic polymer may be selected from a group consisting of a melamine formaldehyde polymer, a melamine urea formaldehyde polymer, a polyurea polymer, a polyurethane polymer, a urea formaldehyde polymer, a polyvinyl alcohol, a polyacrylate, a polymethylmethacry late, a polystyrene, a polyvinylpyrrolidone, or a synthetic copolymer or a combination thereof. In one example embodiment, the synthetic polymer may be a melamine formaldehyde polymer. In oneAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) example embodiment, the synthetic polymer may be a melamine urea formaldehyde polymer. In one example embodiment, the synthetic polymer may be a polyurea polymer. In one example embodiment, the synthetic polymer may be a polyurethane polymer. In one example embodiment, the synthetic polymer may be a urea formaldehyde polymer.

[0038] For instance, in one example embodiment, the capsule wall may be melamine urea formaldehyde. When present, urea may act as a pore widening component of the capsule wall. As such, the molar ratio of urea to melamine in the capsule wall may be from about 1 : 1 to about 1:20, such as from about 1 : 1 to about 1: 15, such as from about 1: 1 to about 1 : 10, such as from about 1 : 1 to about 1 :5, or any range therebetween. For instance, the molar ratio of urea to melamine in the capsule wall may be at least about 1 :2, such as at least about 1:3, such as at least about 1 :4, such as at least about 1 :5. In one example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1 : 1. In another example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1 :4. In another example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1:5. In another example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1 :9. In another example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1:10. In another example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1: 15. In another example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1: 19. In another example embodiment, the molar ratio of urea to melamine in the capsule wall may be at least about 1 :20.

[0039] In one example embodiment, urea may be present in the capsule wall in an amount of from about 10 mol.% to about 99 mol.%, such as from about 15 mol.% to about 97 mol.%. such as from about 20 mol.% to about 95 mol.%, such as from about 25% to about 90%, such as from about 30 mol.% to about 85 mol.%, such as from about 35 mol.% to about 75 mol.%, such as from about 40 mol.% to about 70 mol.%, or any range therebetween. In one example embodiment, for instance, urea may be present in the capsule wall in an amount of from about 10 mol.% to about 99 mol.%. In another example embodiment, for instance, urea may be present in the capsule wall in an amount of from about 15 mol.% to about 97 mol.%. In another example embodiment, for instance, urea may be present in the capsule wall in an amount of from about 20 mol.% to about 95 mol.%. In another example embodiment, for instance, urea may be present in the capsule wall in an amount of from about 25 mol.% to about 90 mol.%. In another example embodiment, for instance, urea may be present in the capsule wall in an amount of from about 30 mol.% to about 85 mol.%. In another exampleAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) embodiment, for instance, urea may be present in the capsule wall in an amount of from about 35 mol.% to about 75 mol.%. In another example embodiment, for instance, urea may be present in the capsule wall in an amount of from about 40 mol.% to about 70 mol.%. Surprisingly, lower urea contents of urea in the capsule wall disturbs the symmetrical melamine formaldehyde network, which consequently lowers the leach resistance of the capsule wall.

[0040] The synthetic polymer and the copper biocide may be versatile agents that may be used in all types of antifouling coatings, e.g., in antifouling coatings based on various synthetic polymers typically used as binders for antifouling coating compositions. Optionally, the synthetic polymer disclosed herein may be combined with different polymers and / or copolymers allowing for the controlled release of the copper biocide may be any polymers and / or copolymers ty pically used as binder in antifouling coatings. Suitable polymers and / or copolymers for that purpose are known to the person skilled in the art. Depending on the amount and kind of binder used, the copper biocide may be released at a predetermined desired rate, e.g.. that is appropriate for the sailing pattern of a ship.

[0041] In one example embodiment, the binder system of ablative coatings includes mostly rosin which reacts with sea water to become water soluble and erode. Alternatively, rosin or rosin derivatives are also used in mixtures with non-erodible binders, such as polyester resin, acrylic resin, epoxy resin, vinyl chloride resin, chlorinated rubber resin, chlorinated polyethylene resin, chlorinated polypropylene resin, styrene-butadiene resin, or polyamide resin. In self-polishing antifouling coatings, the binder system includes mostly hydrolysable acrylate polymers. The hydrolysable functionality is commonly provided to the polymer by either a metal carboxylate acrylate monomer or a silyl acrylate monomer. Erodible polyester binders are also used and result in lower cost antifouling paints. The difference between ablative and self-polishing coatings lies mainly in the thickness of the leached layer and the more linear rate of erosion over time for the self-polishing coating. Hybrid coatings also exist whose binder systems include an erodible acrylate, such as in selfpolishing paints, and rosin. The thickness of the leached layer is thinner than in ablative coatings but thicker than in true self-polishing coatings.

[0042] For example, the polymers and / or copolymers that are used as binders in “selfpolishing antifouling coatings” allowing the controlled release of the copper biocide may include, but is not limited to. hydrolysable acrylate polymers, such as (meth)aciylate based polymers and / or copolymers. The (meth)acrylate monomer moiety in a (meth)acrylate polymer and / or copolymer may be an alkyl (meth)acrylate, for example, a methylAttorney Docket No.: ARXMP-400-PCT (LP3752PC00)(meth)acrylate, ethyl (meth)acrylate. propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate. isobutyl (meth)acrylate, tert-butyl (meth)acrylate. pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, iso-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 3,5,5-trimethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, and stearyl (meth)acrylate; phenyl (meth)acrylate; benzyd (meth)acrylate; an alkoxyalky l (meth)acrylate, such as methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, isobutoxybutyl diglycol (meth)acrylate: a phenoxyethyl (meth)acrylate; a hydroxyalkyl (meth)acrylate, such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, or 2-hydroxy-3-phenoxypropyl (meth)acrylate; the (meth)acrylate monomer moiety7in a (meth)acrylate polymer and / or copolymer may further be a silyl (meth)acrylate, such as tribenzylsilyl (meth)acrylate, trimethylsilyl (meth)acrylate, triethylsilyl (meth)acrylate, tri-isopropylsilyl (meth)acrylate, tri-n-butylsilyl (meth)acrylate, tri-isobutylsilyl (meth)acrylate, tri-t-buty Isily 1 (meth)acrylate, tri-n-amylsilyl (meth)acrylate, tri-n-dodecylsilyl (meth)acrylate, tri-n-hexylsilyl (meth)acrylate, tri-n-octylsilyl (meth)acrylate, tri-n-propylsilyl (meth)acrylate, or triphenylsilyl (meth)acrylate; the (meth)acrylate polymers and / or copolymers may also include a metal salt moiety of acrylic or methacrylic acid, referred to herein as a “metal salt (meth)acrylate.” The metal may be any suitable metal known to the skilled artisan, e.g., zinc, calcium, magnesium, lithium, iron, zirconium, aluminum, cobalt, zirconium, barium, and bismuth.

[0043] In one example embodiment, the polymer and / or copolymer allowing the release of the copper biocide may include, but is not limited to, a (meth)acrylate polymer and / or copolymer, or a VAGH copolymer. The (meth)acrylate polymer and / or copolymer may be a polymer or copolymer of monomer moieties selected from the group consisting of alky l (meth)acrylate. phenyl (meth)acrylate. benzyl (meth)acrylate. alkoxyalkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, zinc (meth)acrylates, and silyl-(meth)acrylate; or the (meth)acrylate polymer and / or copolymer may be a polymer or copolymer of monomer moieties selected from the group consisting of ethyl acrylate, methyl methacrylate, butyl acry late, 2-methoxyethyl acrylate, zinc methacry late, and tri-isopropylsilyl acry late, preferably, the (meth)acrylate polymer and / or copolymer is a copolymer of monomer moieties selected from the group consisting of ethyl acrylate, methyl methacrylate, and zincAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) methacrylate, more preferably, the (meth)acrylate polymer and / or copolymer may be a copolymer of monomer moieties selected from the group consisting of ethyl acrylate, methyl methacrylate, 2-methoxyethyl acry late and zinc methacrylate, and most preferably, the (meth)acrylate polymer polymer and / or copolymer may be a copolymer of monomer moieties selected from the group consisting of methyl methacry late, butyl acrylate, 2-methoxyethyl acrylate and tri-isopropylsilyl acrylate.

[0044] In some example embodiments, the encapsulation efficiency of the copper brocide in the antifouling composition may be at least about 75%, such as at least about 80%, such as at least about 85%, such as at least about 90%, such as at least about 95%, such as at least about 97%. such as at least about 98%, such as at least about 99%. In one example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 75%. In another example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 80%. In another example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 85%. In another example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 90%. In another example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 95%. In another example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 97%. In another example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 98%. In one example embodiment, for instance, the encapsulation efficiency of the copper biocide in the antifouling composition may be at least about 99%.

[0045] In some example embodiments, the total biocide content present in the antifouling composition may include “free” non-encapsulated copper biocide around the microcapsule maybe present in an amount of less than about 1% by weight of the total biocide content in the antifouling composition, such as less than about 0.75% by weight of the total biocide content in the antifouling composition, such as less than about 0.5% by weight of the total biocide content in the antifouling composition. For instance, in one example embodiment, “free” non-encapsulated copper biocide around the microcapsule may be present in an amount of less than about 1 % by weight of the total biocide content in the antifouling composition. In another example embodiment, “free” non-encapsulated copper biocide around the microcapsule may be present in an amount of less than about 0.75% by weight ofAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) the total biocide content in the antifouling composition. In another example embodiment, “free’" non-encapsulated copper biocide around the microcapsule may be present in an amount of less than about 0.5% by weight of the total biocide content in the antifouling composition. Relatively high concentrations of freely available biocide may lead to rapid leaching, a limited quantity can minimize the release rate and potential harm to non-target organisms in the surrounding environment. Beneficially, having a low concentration of free copper biocide in the antifouling composition reduces the amount of biocide leaching into the environment. As the encapsulated biocide gradually diffuses out of the microcapsules over time, it provides sustained antifouling action, extending the service life of the antifouling coating and reducing the need for frequent reapplication. This balanced approach combines immediate effectiveness with environmental responsibility, enhancing the antifouling paint's performance and reducing the ecological footprint of biocide release.

[0046] Consequently, example aspects of the invention further provide an antifouling paint include the antifouling composition allowing the controlled release of the biocidal agent.

[0047] In antifouling paints according to example aspects of the present disclosure, the relative amounts of the synthetic polymer and the biocidal agent may vary depending on, e.g., the nature of the synthetic polymer and the biocidal agent. Advantageously, however, the copper biocide may be present in the antifouling paint from about 5 wt.% to about 70 wt.%, such as from about 8 wt.% to about 70 wt.%, such as from about 10 wt.% to about 70 wt.%, such as from about 15 wt.% to about 70 wt .%, such as from about 20 wt .% to about 70 wt.%, such as from about 30 wt.% to about 70 wt.%, such as from about 40 wt.% to about 70 wt.%, or any range therebetween. For instance, in one example embodiment, the copper biocide may be present in the antifouling paint from about 5 wt.% to about 70 wt.%. In another example embodiment, the copper biocide may be present in the antifouling paint from about 10 wt.% to about 70 wt.%. In another example embodiment, the copper biocide may be present in the antifouling paint from about 15 wt.% to about 70 wt.%. In another example embodiment, the copper biocide may be present in the antifouling paint from about 20 wt.% to about 70 wt.%. In another example embodiment, the copper biocide may be present in the antifouling paint from about 30 wt.% to about 70 wt.%. In another example embodiment, the copper biocide may be present in the antifouling paint from about 40 wt.% to about 70 wt.%.

[0048] Additionally, in one example embodiment, the synthetic polymer may be present in the antifouling paint from about 0.2 wt% to about 20 wt%, preferably from about 0.5 wt% to about 10 wt%, and more preferably from about 1 wt% to about 5 wt%. SuchAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) concentrations have been advantageously found to increase an efficacy of a copper biocide, such as cuprous oxide or copper pyrithione, in the antifouling paints, which allows for lower amounts of the copper biocide as relative to antifouling paints without the encapsulated antifouling compositions described herein. The total content of cuprous oxide in the antifouling paints according to example aspects of the invention may be less than about 50 wt%, more preferably less than about 40 wt%, and most preferably less than about 30 wt%. Thus, the copper biocide of the antifouling paints may be kept at a relatively low level.

[0049] Besides the reduction of the ecological footprint of the biocide release provided herein, the microencapsulation of copper biocides described herein offers additional significant improvements regarding other health, safety, and environment (HS&E) aspects. Of note is the health and safety situation when handling and applying copper containing antifouling paints in shipyards. Encapsulation avoids the direct contact with the hazardous and toxic biocides and therefore improves the occupational safety, an important factor also leading to a more favorable classification and labelling of the copper biocide containing antifouling paints (an important commercial differentiator in the antifouling market).

[0050] The preceding description is exemplary in nature and is not intended to limit the scope, applicability' or configuration of the disclosure in any way. Various changes to the described embodiments may be made in the function and arrangement of the elements described herein without departing from the scope of the disclosure.

[0051] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention is related.

[0052] As used in this application and in the claims, the singular forms “a’', "an", and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises”. The methods and compositions of the present disclosure, including components thereof, can comprise, consist of, or consist essentially of the essential elements and limitations of the embodiments described herein, as well as any additional or optional ingredients, components or limitations described herein or otherwise useful in preservative compositions.

[0053] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, percentages, and so forth, as used in the specification or claims are to be understood as being modified by the term “about”. Accordingly, unless otherwise indicated, implicitly or explicitly, the numerical parameters set forth are approximations that may depend on the desired properties sought and / or limits of detectionAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) under standard test conditions / methods. When directly and explicitly distinguishing embodiments from discussed prior art, the embodiment numbers are not approximates unless the word "about" is recited.

[0054] As used herein, “optional” or “optionally” means that the subsequently described material, event or circumstance may or may not be present or occur, and that the description includes instances where the material, event or circumstance is present or occurs and instances in which it does not. As used herein. “w / w%” and “wt%” mean by weight as relative to another component or a percentage of the total weight in the composition.

[0055] The term “about” is intended to mean approximately, in the region of, roughly, or around. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. Unless otherwise indicated, it should be understood that the numerical parameters set forth in the following specification and attached claims are approximations. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, numerical parameters should be read in light of the number of reported significant digits and the application of ordinary rounding techniques.

[0056] The term “substantially free of’ when used to describe the amount of substance in a material is not to be limited to entirely or completely free of and may correspond to a lack of any appreciable or detectable amount of the recited substance in the material. Thus, e.g., a material is “substantially free of’ a substance when the amount of the substance in the material is less than the precision of an industry-accepted instrument or test for measuring the amount of the substance in the material. In certain example embodiments, a material may be “substantially free of’ a substance when the amount of the substance in the material is less than 10%, less than 9%, less than 8%, less than 7%. less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.5%, or less than 0. 1% by weight of the material.

[0057] The phrase “effective amount” means an amount of a compound that promotes, improves, stimulates, or encourages a response to the particular condition or disorder or the particular symptom of the condition or disorder.

[0058] The term “biocidal agent” as used herein refers to any chemical compound that is intended to inhibit or kill organisms on a surface and / or that prevents or kills the grow th of organisms in an aqueous solution, such as a coolant.Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)

[0059] As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0060] As used herein, the term “D50” refers to the median volume-weighted diameter of a particle size distribution, particularly as measured by laser diffraction. For example, the D50 may be measured using a Mastersizer 3000+ Ultra by Malvern Panalytical.

[0061] Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0062] This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0063] Furthermore, certain aspects of the present disclosure may be better understood according to the following examples, which are intended to be non-limiting and exemplary in nature. Moreover, it will be understood that the compositions described in the examples may be substantially free of any substance not expressly described.EXAMPLESExample 1

[0064] The release rate of an encapsulated copper biocide disclosed herein was explored. Overall, the antifouling composition disclosed herein provides a microencapsulated biocide product (CuPT, CmO) with a low Tree' (non-encapsulated) active content. This requires an encapsulation process with a high encapsulation efficiency (EE%). An encapsulation of the almost water insoluble biocides copper pyrithione (0.05 ppm in water) and Cuprous oxide (below 0.01 ppm in water) - further reducing the bioavailability of the active substances - seems counterintuitive with regard to a high antifouling efficacy required for marine coatings. Thus, the technical challenge is to provide a high encapsulation efficiency without compromising on the biocidal performance of the actives. The technical solution to addressAttorney Docket No.: ARXMP-400-PCT (LP3752PC00) these opposing goals is to manipulate the capsule wall in order to fine-tune / increase the biocide release rates: a) by minimizing the capsule wall thickness; b) by introducing larger micropores; c) by increasing the hydrophilicity of the micropores (e.g. by reducing the curing level of the polymer wall leading to a more open pore structure with unreacted, hydrophilic hydroxyl groups). A combination of two or three of these approaches also proved to be feasible. These modifications provide Tower performing', i.e. more easily leachable capsules or polymeric carriers for MAF actives with leach rates high enough to provide a sufficient bioavailability for an effective preservation in Marine Antifouling applications.

[0065] Prior to determining the release rate of the copper biocide, the maximum solubility of CuPT in the test solvent (or solvent mixture) was determined to avoid a copper pyrithione over-dosage during the release-to-solvent (RTS) test. Next, the CR-CuPT prototypes were combined with a solvent in an Erlenmeyer flask. The solvent samples were incubated under continuous shaking for up to 96 hours. Solvent samples were taken at certain time intervals (including at Oh, 2h, 4h, 8h, 16h, 24h, 48h, 72h, etc.). Subsequently, the solvent samples were filtered through a 0.2 pm filter and analyzed by HPLC to determine the increase of the copper pyrithione (CuPT) content dissolved in the test solvent, e.g. Xylene (Figure 1).

[0066] As seen in Figure 1, the CuPT release rate of a MUF (urea / melamine molar ratio: 20 / 80) encapsulated CuPT is very high and matches the bioavailability of the nonencapsulated CuPT (”non-CR“) reference material. Another prototype with a high biocide leach rate is the ‘undercured’ MF encapsulated prototype. Interestingly, the MUF (urea / melamine molar ratio: 50 / 50) encapsulated CuPT shows a much higher leach resistance especially over the first 48 hours, which can be explained with the 1 : 1 molar ratio of urea and melamine which leads to a highly symmetrical and therefore tight capsule wall. Lower urea contents of 10 mol.% and especially 20 mol.% urea disturb the symmetrical melamine formaldehyde network which consequently lowers the leach resistance of the capsule wall.*CuPT content determined by HPLC analysis** Abbreviations: MUF = Melamine urea formaldehyde resin, MF (uc) = under-cured Melamine formaldehyde resin.Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)

[0067] Further seawater-based experiments confirm the impact of urea on the modification of the biocide release rates from MF / MUF microcapsules, important for the end application, i.e. for the performance of antifouling paints. To do so. a performance test was conducted on biocide protypes described herein. A performance test or release-to-(sea)water test quantifies the biocide release from the microcapsules into sea water. The smaller the percentage of ‘free’ biocides found in the water phase, the higher the leach resistance. Tested are the ’naked’ capsules (i.e. without any coating) in a large excess of water under continuous shaking.Example 2

[0068] Release rates of various copper biocide formulations with differing modified capsule wall properties were investigated. To do so. encapsulated biocide samples including about 15 mg / L CuPT or CU2O content each were weighed into 500 ml Erlenmeyer flasks filled with 400 ml sea water. These flasks were then placed on an orbital shaker plate and CuPT samples for HPLC analysis are taken initially every 15 minutes, later every 30 minutes. For CU2O Inductively Coupled Plasma Mass Spectrometry (ICP-MS) measurements were used to track the free copper content in sea water in this leaching experiment. It was found that the biocide (CuPT or C112O) release rates can be adjusted / manipulated in a wide range by modifying the capsule wall chemistry allowing the development of tailor-made controlled- release products for various end application scenarios (Table 2-4).*CuPT content determined by HPLC analysis** Abbreviations: MF = Melamine formaldehyde resin, MUF = Melamine urea formaldehyde resin, MF (uc) = under-cured Melamine formaldehyde resin.Table 3: CuPT Results after 180 minutes of leaching into sea water (Figure 3)Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)*CuPT content determined by HPLC analysis** Abbreviations: MF = Melamine formaldehyde resin, MUF = Melamine urea formaldehyde resin, MF (uc) = under-cured Melamine formaldehyde resin.Table 4: C112Q Results after 360 minutes of leaching into sea water (Figure 4)*ICP-MS cannot differentiate between Cu( I ) and Cu(II)2+ions. Without wishing to be bound by theory, Cu(II)2+ions might occur as impurities in cuprous oxide or as a result of oxidation reactions in the formulation process or during storage / handling steps.** Abbreviations: MUF = Melamine urea formaldehyde resin.Example 3

[0069] Field tests were conducted for eleven months for various microencapsulated copper pyrithione (CuPT) and cuprous oxide (CU2O) prototypes tested in two different paint systems (a rosin-based paint (ablative coating) and a silyl polymer-based paint (self-polishing coating)). Subsequently, the antifouling performance after eleven months of exposure time in sea water was evaluated (Table 5). In Table 5, the values marked bold show a performance improvement with regard to antifouling characteristics of the encapsulated biocides compared to corresponding non-encapsulated reference samples, for example:T31-03 vs T31-01, i.e. 0% vs 3%;T31-06 and T31-08 vs T31-04, i.e. 0% and 0% vs 1%;T31-11 and T31-12 vs T31-10, i.e. 10% and 10% vs. 40%; and T31-16 and T31-17 vs T31-13, i.e. 3% and 1% vs. 5%,Table 5: Test panel evaluation of antifouling performance after eleven-month exposure time in sea water in Himeji (Japan)Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)“'Performance ratings (biofouling coverage in %): rated was the total coverage rate of sessile organisms (animals) according to ASTM D6990-05 (201 1 ). The lower the percentage value, the better the antifouling performance.* *E1 = encapsulated biocide, process 1 (melamine urea formaldehyde resin); E2 = encapsulated biocide, process 2 (Calcium alginate); E3 = encapsulated biocide, process 3 (melamine formaldehyde resin, version A); E4 = encapsulated biocide, process 4 (melamine formaldehyde resin, version B).Example 4

[0070] The thickness of particle layers encapsulated with a synthetic polymer was analyzed using Focused Ion Beam (FIB) measurements. Figures 5 and 6 depict Scanning Electron Microscopy (SEM) images of gold-coated particles. An FIB cross-section of a particle agglomerate was created. For this purpose, as is customary with FIB cuts, a local protective layer of Pt-C was deposited at the site of the FIB cut to prevent rounding of the cross-section towards the surface. The Pt-C and Au layers are clearly visible. In the circled area of Figure 5, a distinct fringe between the Au layer and the particles can be observed. The thickness of the fringe is about 20-25 nm (Figure 6).

[0071] Additionally, Energy Dispersive X-ray spectroscopy (EDX) mappings of the FIB cross-section were generated (not depicted). Although the lateral resolution of the EDX measurement is physically severely limited and is in the range of a few hundred nanometers, one can still discern an N-rich border of the particles, indicating the presence of the synthetic, Melamine-based capsule wall poly mer.

[0072] These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.

Claims

Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)What Is Claimed;1. An antifouling composition, the composition comprising a plurality of particles comprising copper biocide; and a synthetic polymer encapsulating each of the plurality of particles; wherein the amount of non-encapsulated copper biocide in the antifouling composition is less than about 1 % by weight of the total biocide content in the antifouling composition.

2. The antifouling composition of claim 1, wherein the copper biocide comprises copper pyrithione, cuprous oxide, copper (I) thiocyanate, or a combination thereof.

3. The antifouling composition of claim 1, wherein the copper biocide comprises copper pyrithione.

4. The antifouling composition of claim 1, wherein the copper biocide comprises cuprous oxide.

5. The antifouling composition of claim 1, wherein the synthetic polymer is at least partially crosslinked.

6. The antifouhng composition of claim 1, wherein the synthetic polymer is selected from a group consisting of melamine formaldehyde, urea formaldehyde, melamine urea formaldehyde, or a combination thereof.

7. The antifouling composition of claim 6, wherein the synthetic polymer comprises melamine formaldehyde.

8. The antifouling composition of claim 6, wherein the synthetic polymer comprises melamine urea formaldehyde.

9. A microcapsule, comprising: an encapsulated material comprising a copper biocide; and a capsule wall comprising a synthetic polymer; wherein the amount of non-encapsulated copper biocide around the microcapsules is less than about 1% by weight of the total biocide content in the antifouling composition.

10. The microcapsule of claim 9, wherein the copper biocide is present in the microcapsule in an amount of from about 10% to about 95% by weight.

11. The microcapsule of claim 9, wherein the copper biocide comprises copper pyrithione, cuprous oxide, copper (I) thiocyanate, or a combination thereof.

12. The microcapsule of claim 9. wherein the copper biocide comprises copper pyrithione.

13. The microcapsule of claim 9, wherein the copper biocide comprises cuprous oxide.Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)14. The microcapsule of claim 9, wherein the capsule wall comprises a water insoluble synthetic polymer.

15. The microcapsule of claim 9, wherein the synthetic polymer is at least partially crosslinked.

16. The microcapsule of claim 9, wherein the synthetic polymer is selected from a group consisting of melamine formaldehyde, urea formaldehyde, melamine urea formaldehyde or a combination thereof.

17. The microcapsule of claim 16, wherein the synthetic polymer comprises melamine formaldehyde.

18. The microcapsule of claim 16, wherein the synthetic polymer comprises melamine urea formaldehyde.

19. An antifouling paint, the paint comprising a plurality of the microcapsules of claim 9 allowing controlled release of the copper biocide, wherein the encapsulation efficiency rate of the microencapsulated antifouling composition is more than about 75%.

20. The antifouling paint of claim 19, wherein the encapsulation efficiency rate of the microencapsulated antifouling composition is more than about 95%.

21. The antifouling paint of claim 19, wherein the amount of copper biocide of the microcapsule present in the antifouling paint is from about 5 wt.% to about 70 wt.% by weight.

22. The antifouling paint of claim 19, wherein the copper biocide comprises copper pyrithione, cuprous oxide, copper (I) thiocyanate, or a combination thereof.

23. The antifouling paint of claim 22, wherein the copper biocide comprises copper pyrithione.

24. The antifouling paint of claim 22, wherein the copper biocide comprises cuprous oxide.

25. The antifouling paint of claim 19, wherein the capsule wall comprises a water insoluble synthetic polymer.

26. The antifouling paint of claim 19, wherein the synthetic polymer is at least partially crosslinked.

27. The antifouling paint of claim 19, wherein the synthetic polymer is selected from a group consisting of melamine formaldehyde, urea formaldehyde, melamine urea formaldehyde or a combination thereof.

28. The antifouling paint of claim 27, wherein the synthetic polymer comprises melamine formaldehyde.Attorney Docket No.: ARXMP-400-PCT (LP3752PC00)29. The antifouling paint of claim 27, wherein the synthetic polymer comprises melamine urea formaldehyde.

30. The antifouling paint of claim 19, wherein the capsule wall further comprises a pore widening component.

31. The antifouling paint of claim 30, wherein the amount of the pore widening component is from about 1 mol.% to about 99 mol.% in the capsule wall.

32. The antifouling paint of claim 30, wherein the amount of the pore widening component is from about 10 mol.% to about 50 mol.% in the capsule wall.

Images