Soil release coating composition, substrate coated with such coating composition, and use of such coating composition

Abstract

The present invention relates to a non-aqueous liquid fouling release coating composition for controlling fouling of aquatic organisms on artificial objects, comprising: i) a moisture curable polysiloxane comprising repeat units of formula (I) and at least one end or pendant group of formula (II), and ii) at least one marine biocide or a non-volatile component comprising units selected from hydrocarbyl, heterohydrocarbyl, halogenated hydrocarbyl, ethers, esters, amides, ketones, siloxanes, carbamates or urea groups. The invention further relates to a substrate coated with the coating composition and to the use of the coating composition for controlling aquatic organism fouling of artificial objects. # imgabs0 #

Description

[0001] This application is a divisional application of the patent application with the application number 201880006444.2. The filing date of the original application is January 12, 2018, and the invention title is "Fouling Release Coating Composition, Substrate Coated with Such Coating Composition, and Use of Such Coating Composition". Field of the Invention

[0002] The present invention relates to a non-aqueous liquid foul release coating composition for controlling fouling by aquatic organisms on artificial objects, a substrate coated with the coating composition, and the use of the coating composition for controlling fouling by aquatic organisms on artificial objects. Background of the Invention

[0004] Artificial structures such as ships and boats, buoys, drilling platforms, dry dock equipment, oil rigs, and aquaculture equipment, as well as nets and pipelines immersed in water or through which water flows, are prone to fouling by aquatic organisms such as green and brown algae, barnacles, mussels, etc. Such structures are usually metallic, but may also include other structural materials such as concrete, glass-reinforced plastics, or wood. Such fouling causes problems on ship hulls because it increases the frictional resistance during movement in water, resulting in reduced speed and increased fuel consumption. It causes problems on static structures such as drilling platforms and supports for oil and gas extraction, refining, and storage facilities, firstly because the resistance of a thick fouling layer to waves and water flow can cause unpredictable and potentially dangerous stresses in the structure, and secondly because fouling makes it difficult to inspect for defects such as stress cracking and corrosion in the structure. It causes problems in pipelines such as cooling water inlets and outlets because the effective cross-sectional area is reduced due to fouling, resulting in a reduced flow rate.

[0005] For example, as disclosed in GB1307001 and US3702778, it is known that silicone rubber coatings can resist fouling by aquatic organisms. It is believed that such coatings result in a surface that is not easily adhered to by organisms, and thus they can be referred to as fouling release coatings or fouling resistant coatings, rather than anti-fouling coatings. Silicone rubber and silicone compounds generally have very low toxicity. When applied to ship hulls, the disadvantage of such anti-fouling systems is that although the accumulation of marine organisms is reduced, a relatively high ship speed is required to remove all fouling species. Thus, in some cases, it has been shown that in order to effectively release from a ship hull treated with such a polymer, it must be sailed at a speed of at least 14 knots.

[0006] WO2014 / 131695 describes anti-fouling compositions that comprise a polymer containing organosiloxane and a polymer or oligomer containing fluorinated alkylene oxide. The compositions generally contain a tin-based curing catalyst.

[0007] Commercially available fouling release coating systems based on polysiloxanes require a curing catalyst, which is typically a tin-based catalyst. Due to the toxicity issues associated with tin compounds, tin-based catalysts are facing increasing disfavor. Other less hazardous catalysts are available; however, they generally have an adverse effect on key coating properties such as drying time, pot life, or antifouling performance.

[0008] US2015 / 0329724 describes an antifouling coating composition comprising a silicone-containing polymer having hydrolyzable and condensable groups, a crosslinking agent, and a zinc complex as a curing catalyst.

[0009] There is a need for fouling release coatings that provide improved fouling protection, especially at low ship speeds or under static conditions. There is also a need for fouling release coatings having excellent adhesion to substrates, compositions with an improved balance of pot life (working life) and drying time after opening, especially when drying at low temperatures is required. Summary of the Invention

[0011] The present invention provides a fouling release coating composition that eliminates or alleviates the above problems.

[0012] Thus, in a first aspect, the present invention provides a non-aqueous liquid fouling release coating composition for controlling aquatic biofouling on artificial objects, comprising:

[0013] i) a moisture-curable polysiloxane comprising repeating units of formula (I) and at least one terminal or side group of formula (II):

[0014]

[0015] wherein R 1 and R 2 are independently organic groups having 1 - 20 carbon atoms; R 3 and R 4 are independently organic groups having 1 - 20 carbon atoms; A is an organic group having 1 - 50 carbon groups; R 5 is independently selected from organic groups having 1 - 20 carbon atoms and groups of formula O-R 6 wherein R 6 is an organic group having 1 - 20 carbon atoms, provided that at least one R 5 is a group of formula O-R 6 and ii) at least one marine biocide or a non-volatile component comprising units selected from hydrocarbyl, heterohydrocarbyl, halohydrocarbyl, ether, ester, amide, ketone, siloxane, carbamate, or urea groups.

[0016] Compared with known antifouling coatings, the fouling release coating composition of the present invention provides a coating with improved antifouling performance. Even at low ship speeds or under static conditions, organisms cannot easily adhere to the coating. The coating composition has an improved balance of usability (pot life) and drying time, especially when drying at low temperatures, and the coating shows improved adhesion to the substrate. Without a curing catalyst, the coating composition cures very well. Therefore, no tin-based curing catalyst or other catalyst is required, and preferably these catalysts are absent.

[0017] In a second aspect, the present invention provides a substrate coated with the fouling release coating composition according to the first aspect of the present invention.

[0018] After applying the coating composition to the substrate and drying, curing or crosslinking, the coated substrate can be immersed to provide fouling protection.

[0019] Accordingly, in a third aspect, the present invention provides a method for controlling aquatic biofouling on an artificial object, comprising the steps of:

[0020] a) applying the fouling release coating composition according to the first aspect of the present invention to at least a part of the surface of the artificial object;

[0021] b) curing the coating composition to form a cured coating; and

[0022] c) immersing the artificial object at least partially in water.

[0023] In a last aspect, the present invention provides the use of the fouling release coating composition according to the first aspect of the present invention for controlling aquatic biofouling on an artificial object. Detailed Description of the Invention

[0025] The fouling release coating composition of the present invention is a liquid coating composition. This means that the composition is liquid at ambient temperature and can be applied to a substrate by known techniques such as brushing, rolling, dipping, bar coating or spraying.

[0026] In one embodiment, the coating composition comprises a volatile organic solvent to obtain the desired application viscosity. Alternatively, the coating composition may be substantially or completely free of volatile organic solvents, for example when the polysiloxane is liquid and has a sufficiently low viscosity, or when a reactive diluent or liquid plasticizer is included. The coating composition is a non-aqueous coating composition. This means that the composition is provided in a form that is substantially free or completely free of water. Substantially free of water means that the composition contains 0 - 5 wt%, preferably 0 - 2 wt% water, based on the total weight of the composition. The amount of water may be inadvertently introduced by the components contained in the coating composition, for example by pigments or organic solvents that contain small amounts of water as impurities.

[0027] An essential component of the coating composition is a moisture-curable polysiloxane comprising repeating units of formula (I) and at least one end group or side group of formula (II):

[0028]

[0029] wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and A are as described above.

[0030] An organic group is a group containing at least one carbon atom. Generally, the organic groups R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and A are linear, branched or cyclic organic groups, such as aliphatic or aromatic organic groups. The definition of organic groups also encompasses oligomeric siloxanes or polysiloxanes.

[0031] In one embodiment, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and A are independently hydrocarbon groups, heterohydrocarbon groups or halogenated hydrocarbon groups.

[0032] R 3 and R 4 are organic groups having 1 - 20 carbon atoms. In one embodiment, the organic groups R 3 and R 4 are only indirectly connected to each other through the nitrogen atom in formula (II). In another embodiment, the organic groups R 3 and R 4are also directly connected to each other by additional covalent bonds, thus representing a cyclic amine structure. For example, R 3 and R 4 together with the nitrogen atom of formula (II) can represent a pyrrolidine or piperidine ring.

[0033] Preferably, R 3 and R 4 are independently straight-chain, cyclic or branched aliphatic hydrocarbon groups without heteroatoms, having 1 - 10 carbon groups, more preferably 1 - 8 carbon atoms. In one embodiment, R 3 and R 4 are each butyl.

[0034] As used herein, the term "hydrocarbyl" means a monovalent group formed by removing a hydrogen atom from a hydrocarbon such as a straight-chain, branched, cyclic, aliphatic, aryl, aralkyl or alkaryl hydrocarbon,

[0035] As used herein, the term "heterohydrocarbyl" means a hydrocarbyl group containing heteroatoms such as oxygen, sulfur, nitrogen or silicon introduced within the chain or ring.

[0036] As used herein, the term "halohydrocarbyl" means a hydrocarbyl group in which one or more hydrogen atoms are replaced by halogen atoms such as fluorine, chlorine or bromine atoms.

[0037] In formula (I), R 1 and R 2 are independently selected from straight-chain, cyclic or branched organic groups having 1 - 20 carbon atoms. In one embodiment, the organic group is a hydrocarbyl group without heteroatoms. Alternatively, the organic group may contain heteroatoms or heteroatom-containing groups such as ether, ester, amide, sulfide, haloalkyl, siloxane, carbamate or urea groups. More preferably, R 1 and R 2 are each independently methyl or phenyl.

[0038] In formulas (II) and (III), the R 5 groups are suitably selected from straight-chain, cyclic or branched aromatic or aliphatic organic groups having 1 - 20 carbon atoms and groups of the formula O-R 6 , where R 6 is a straight-chain, cyclic or branched aliphatic organic group having 1 - 20 carbon atoms, provided that at least one R 5 group is a group of the formula O-R 6 . The straight-chain, cyclic or branched aromatic or aliphatic organic groups are preferably alkyl groups having 1 - 6 carbon atoms.

[0039] The presence of the O-R 6 group provides water curability to the polysiloxane. Preferably, at least two R 5 groups are of the formula O-R 6group. In another preferred embodiment, R 5 groups are selected from C 1 -C 4 alkoxy groups, especially ethoxy groups.

[0040] Suitable moisture-curable polysiloxanes can be prepared by reacting a hydroxy-functional polysiloxane having repeating units of formula (I) as defined above with an aminosilane of formula (III):

[0041]

[0042] wherein R 3 -R 5 and A are as defined above, and wherein at least one R 5 group is a group of the formula O-R 6 The reaction is described in Chinese published patent CN101134887, which is incorporated herein by reference. This document describes the reaction of α,ω-dihydroxypolydimethylsiloxane with α-aminomethyltrialkoxysilane. To ensure sufficient conversion of the hydroxy groups of the hydroxy-functional polysiloxane having repeating units of formula (I) and the aminosilane of formula (III), it may be advantageous to use a molar excess of the aminosilane of formula (III) during the reaction. After the reaction, any unreacted excess aminosilane can be removed. However, any excess unreacted aminosilane can also be retained in the moisture-curable polysiloxane. Once the coating composition is applied to a substrate, any excess aminosilane can participate in the curing reaction as a curing agent. In addition, the aminosilane can reduce the viscosity of the coating composition and reduce the need for volatile organic solvents as diluents. Therefore, it is preferred that the coating composition of the present invention further comprises an aminosilane of formula (III). The aminosilane of formula (III) can be used in any suitable amount, usually up to 10% by weight, preferably 0.5 - 7% by weight, even more preferably 1 - 5% by weight, based on the weight of the moisture-curable polysiloxane.

[0043] In one embodiment, the group A in formulas (II) and (III) is a linear, cyclic or branched aliphatic organic group having 1 - 10 carbon atoms, preferably a hydrocarbon group without heteroatoms having 1 - 10 carbon atoms, more preferably 1 - 8 carbon atoms, even more preferably 1 - 6 carbon atoms. Very good results are obtained in embodiments where A is methylene (-CH 2 -). Therefore, in a preferred embodiment, A is methylene.

[0044] The moisture-curable polysiloxane can be linear or branched. In one embodiment, the moisture-curable polysiloxane is substantially linear and has two end groups of formula (II).

[0045] In one embodiment, the moisture-curable polysiloxane consists essentially of repeating units of formula (I) and end or side groups of formula (II). In an alternative embodiment, the moisture-curable polysiloxane contains other groups which may form part of the polymer backbone or may be side chains of the polymer backbone. Examples of other groups include ether moieties, polyether moieties and fluorinated alkyl groups.

[0046] One advantage of the anti-fouling coating composition of the present invention is that after the composition is applied to a substrate, the curing reaction of the moisture-curable polysiloxane can proceed without a curing catalyst. Thus, it is generally preferred that the coating composition does not contain a curing catalyst.

[0047] In a particularly preferred embodiment, the coating composition comprises an aminosilane of formula (III); the group A in formulas (II) and (III) is methylene; and the coating composition does not contain a curing catalyst. It has been found that in this embodiment, the aminosilane of formula (III) acts as a crosslinking agent (curing agent) in terms of the degree to which the coating composition cures within an acceptable time and in the absence of a curing catalyst.

[0048] However, in certain cases it may be desirable to further increase the curing rate by adding a curing catalyst to the coating composition.

[0049] Examples of suitable catalysts include carboxylates of various metals such as tin, zinc, iron, lead, barium and zirconium. The salt is preferably a salt of a long-chain carboxylic acid, such as dibutyltin dilaurate, dibutyltin dioctoate, iron stearate, tin(II) octoate and lead octoate. Other examples of suitable catalysts include organobismuth and organotitanium compounds and organophosphoric esters, such as bis(2-ethylhexyl) hydrogen phosphate. Other possible catalysts include chelates, such as dibutyltin acetylacetonate. In addition, the catalyst may include a halogenated organic acid which has at least one halogen substituent on a carbon atom in the α-position relative to the acid group and / or at least one halogen substituent on a carbon atom in the β-position relative to the acid group, or a derivative which can be hydrolyzed to form such an acid under the conditions of the condensation reaction. Alternatively, the catalyst may be as described in any one of WO2007122325A1, WO2008055985A1, WO2009106717A2, WO2009106718A2. Combinations of the above substances may also be used.

[0050] In addition to the moisture-curable polysiloxane, the coating composition comprises a second component to provide enhanced fouling protection. The second component is a marine biocide or a non-volatile component comprising units selected from hydrocarbyl, heterohydrocarbyl, halohydrocarbyl, ether, ester, amide, ketone, siloxane, urethane or urea groups.

[0051] The biocide can be one or more of inorganic, organometallic, metal-organic or organic biocides for marine or fresh water organisms. Examples of inorganic biocides include copper salts such as copper oxide, copper thiocyanate, copper bronze, copper carbonate, copper chloride, copper-nickel alloy, and silver salts such as silver chloride or silver nitrate; organometallic and metal-organic biocides include zinc pyrithione (zinc salt of 2-pyridinethiol-1-oxide), zinc copper pyrithione, bis(N-cyclohexyldiazenium) dioxo) copper, zinc ethylenebis(dithiocarbamate) (i.e., zineb), zinc dimethyldithiocarbamate (ziram) and manganese ethylenebis(dithiocarbamate) coordinated with zinc salt (i.e., mancozeb); organic biocides include formaldehyde, dodecylguanidine monohydrochloride, thiabendazole, N-trichloromethylthio phthalimide, trichloromethylthio thioamide, N-arylmaleimide such as N-(2,4,6-trichlorophenyl) maleimide, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, 2-methylthio-4-butylamino-6-cyclopropylamino-s-triazine, 3-benzothiophen-5,6-dihydro-1,4,2- thiazine 4-oxide, 4,5-dichloro-2-n-octyl-3(2H)-isothiazolone, 2,4,5,6-tetrachloroisophthalonitrile, tolylfluanid, dichlofluanid, diiodomethyl p-tolylsulfone, capsaicin or substituted capsaicin, N-cyclopropyl-N'-(1,1-dimethylethyl)-6-methylthio-1,3,5-triazine-2,4-diamine, 3-iodo-2-propynyl butylcarbamate, medetomidine, 1,4-dithioanthraquinone-2,3-dicarbonitrile (dithianon), boranes such as pyridine triphenylborane, 2-trichloromethyl-3-halo-4-cyanopyrrole derivatives substituted at the 5-position and optionally substituted at the 1-position, such as 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethylpyrrole (tralopyril) and furanones, such as 3-butyl-5-(dibromomethylene)-2(5H)-furanone, and mixtures thereof, macrolides such as avermectin, such as avermectin B1, ivermectin, doramectin, abamectin and selamectin, and quaternary ammonium salts such as didecyldimethylammonium chloride and alkyldimethylbenzylammonium chloride. ​

[0052] Optionally, the biocide is fully or partially encapsulated, adsorbed, entrapped, loaded or bound. Some biocides are difficult to handle or are harmful during handling and are advantageously used in encapsulated, entrapped, absorbed, loaded or bound form. Encapsulation, entrapment, absorption, loading or binding of the biocide can provide an auxiliary mechanism for controlling the leaching of the biocide from the coating system, thus achieving a more uniform release and a long-lasting effect.

[0053] For the present invention, there is no particular limitation on the method of encapsulating, entrapping, adsorbing, loading or binding the biocide. Examples of methods for preparing encapsulated biocides for the present invention include single-wall and double-wall aminoplast or hydrolyzed polyvinyl acetate-phenolic resin capsules or microcapsules as described in EP 1791424.

[0054] An example of a suitable encapsulated biocide is encapsulated 4,5-dichloro-2-n-octyl-3(2H)-isothiazolone sold by Dow Microbial Control as Sea-NineCR2Marine Antifoulant Agent.

[0055] Examples of methods for preparing absorbed or loaded or bound biocides include using host-guest complexes, such as inclusion compounds as described in EP0709358, phenolic resins as described in EP0880892, carbon-based adsorbents, such as those described in EP1142477, or inorganic microporous carriers, such as amorphous silica, amorphous alumina, pseudoboehmite or zeolites as described in EP1115282.

[0056] Taking into account the environmental and health issues associated with the use of biocides in coatings to prevent fouling by aquatic organisms, the second component is preferably not a marine biocide. In this case, the coating composition may be substantially or completely free of marine biocides. In a preferred embodiment, enhanced fouling protection is provided by a non-biocidal component, which is a non-volatile component comprising units selected from hydrocarbyl, heterohydrocarbyl, halohydrocarbyl, ether, ester, amide, ketone, siloxane, urethane or urea groups.

[0057] If a component does not boil at a temperature below 250 °C at atmospheric pressure, the component is considered non-volatile. Preferably, the component is an immiscible fluid or grease. Examples include siloxanes, organic or inorganic molecules or polymers, usually liquids, but optionally also organic-soluble greases or waxes, which are immiscible (in whole or in part) with the cured moisture-curable polysiloxane. It is believed that the non-volatile second component will be enriched on the surface of the cured coating and enhance its fouling release performance.

[0058] Suitable examples of the non-volatile second component of the coating composition include fluorinated polymers or oligomers, such as linear and branched trifluoromethyl fluoride-terminated perfluoropolyethers (e.g., Fomblin Krytox fluids or Demnum oil); linear diorgano(OH)-terminated perfluoropolyethers (e.g., Fomblin Z Fluorolink ); low molecular weight polychlorotrifluoroethylene (e.g., Daifloil fluids). Other mono- and diorgano-functional terminated polymers or oligomers containing fluorinated alkyl or alkoxy groups can also be used, such as carboxyl or ester-functional polymers or oligomers containing fluorinated alkyl or alkoxy groups.

[0059] Other examples of the second component of the coating composition include silicone oils, such as the following formula:

[0060] Q 3 Si-O-(SiQ 2 -O-)nSiQ 3

[0061] where each group Q represents a hydrocarbon group having 1-10 carbon atoms, and n is an integer such that the viscosity of the silicone oil is 20-5000 mPa·s. At least 10% of the groups Q are usually methyl, and at least 2% of the groups Q are phenyl. Most preferably, at least 10% of the -S1Q 2 -O- units are methylphenylsiloxane units. Most preferably, the silicone oil is methyl-terminated poly(methylphenylsiloxane). The viscosity of the oil is preferably 20-1000 mPa·s. Examples of suitable silicone oils are sold under the trade names Rhodorsil Huile510V100 and Rhodorsil Huile 550 by Bluestar Silicones.

[0062] Other examples of the second component of the coating composition include sterols and / or sterol derivatives. Sterols and sterol esters are triterpenoid compounds, which are a class of organic molecules derived from triterpene molecules. Sterols and sterol derivatives can be derived from natural sources such as animals and plants. Examples of sterols include cholesterol, lanosterol, lathosterol, 7-dehydrocholesterol, cholecalciferol, desmosterol, 7-desmostanol, cholestanol, coprostanol, campesterol, stigmasterol, sitosterol, avenasterol, stigmastenol, brassicasterol, 4-norsterols (i.e., without a substituent at carbon-4), 4α-monomethylsterols and 4,4-dimethylsterols, phytostanols (fully saturated), ergosterol, fragrantin and cycloartenol. Suitable mixtures containing sterols and sterol derivatives are lanolin, acylated lanolin, alkoxylated lanolin and lanolin oil.

[0063] Other examples of the second component of the coating include hydrophilically modified polysiloxanes, such as polyoxyalkylene-modified polysiloxanes, such as polysiloxanes grafted with polyoxyalkylene chains, polysiloxanes having polyoxyalkylene chains introduced into their main chains, or polysiloxanes having polyoxyalkylene chains introduced into their main chains and having polyoxyalkylene chains grafted thereto. Commercially available such hydrophilically modified polysiloxane oils include DC5103, DC Q2-5097, DC193, DC Q4-3669, DC Q4-3667, DC57 and DC2-8692 (all from Dow Corning) and BYK333.

[0064] In one embodiment, when the coating cures, the second component ii) of the coating composition can be covalently linked to the moisture-curable polysiloxane i).

[0065] However, it is preferred that the second component of the coating composition does not participate in the moisture-induced curing reaction of the polysiloxane. Thus, in a preferred embodiment, this component does not contain groups of formula (II).

[0066] In another embodiment, a non-biocidal non-volatile second component is combined with a marine biocide.

[0067] The fouling release coating composition may also contain other ingredients such as fillers, pigments, wetting agents, dispersants, flow additives, rheology modifiers, adhesion promoters, antioxidants, UV stabilizers, organic solvents, organic polymers, reactive diluents, plasticizers and catalysts.

[0068] Examples of suitable fillers are barium sulfate, calcium sulfate, calcium carbonate, silica or silicates (such as talc, feldspar and kaolin), including pyrogenic silica, bentonite and other clays, and solid silicone resins, which are usually condensed branched polysiloxanes, such as those containing the formula SiO4 / 2 The Q unit and formula R of m 3 SiO 1 / 2 of the M unit of silicone resin, where R m The substituents are selected from alkyl groups having 1-6 carbon atoms, and the ratio of the M unit to the Q unit is 0.4:1-1:1. Some fillers such as fumed silica may have a thixotropic effect on the coating composition. The proportion of the filler can be 0-25% by weight, based on the total weight of the coating composition. Preferably, the clay is present in an amount of 0-1% by weight, and preferably the thixotropic agent is present in an amount of 0-5% by weight, based on the total weight of the coating composition.

[0069] Examples of pigments include iron oxide black, iron oxide red, iron oxide yellow, titanium dioxide, zinc oxide, carbon black, graphite, molybdate red, molybdate yellow, zinc sulfide, antimony oxide, sodium aluminium sulfosilicate, quinacridones, phthalocyanine blue, phthalocyanine green, indanthrone blue, cobalt aluminate, carbazole di azine, chromium oxide, isoindoline orange, tolidiole, benzimidazolone, quinophthalone yellow, isoindoline yellow, tetrachloroisoindolinone and quinophthalone yellow, metal sheets (such as aluminum sheets) or other so-called barrier pigments or anti-corrosive pigments such as zinc powder or zinc alloy; or other so-called lubricant pigments, such as graphite, molybdenum disulfide, tungsten disulfide or boron nitride. The volume concentration of the pigment is preferably 0.5-25%. The proportion of the pigment can be 0-25% by weight, based on the total weight of the coating composition.

[0070] Suitable solvents for the coating composition include aromatic hydrocarbons, alcohols, ketones, esters, and mixtures of the above substances with each other or aliphatic hydrocarbons. Preferred solvents include ketones such as methyl isopentyl ketone and / or hydrocarbon solvents, such as xylene, trimethylbenzene, or aliphatic cyclic or acyclic hydrocarbons, and mixtures thereof.

[0071] The coating composition preferably has a non-volatile content of at least 35% by weight, more preferably at least 50% by weight, and even more preferably at least 70% by weight, defined as the weight percentage of non-volatile substances in the coating composition. The non-volatile content can be as high as 80% by weight, 90% by weight, 95% by weight, and preferably up to 100% by weight. The non-volatile content can be determined according to ASTM method D2697.

[0072] In a second aspect, the present invention relates to a substrate coated with a soil release coating composition according to the first aspect of the present invention. The coating composition can be applied to the substrate by techniques known in the art, such as brushing, rolling, dipping, bar coating, or spraying (airless and conventional).

[0073] The coating composition according to the first aspect of the present invention provides a coating having very good anti-fouling and fouling release properties. This makes these coating compositions very suitable for coating objects immersed in an aqueous environment, such as marine and aquaculture applications. The coatings can be used for dynamic and static structures, such as ship and boat hulls, buoys, drilling platforms, oil rigs, floating production storage and offloading vessels (FPSOs), floating storage and regasification units (FSRUs), cooling water inlets of power plants, fishing nets or cages, and pipes immersed in water.

[0074] The substrate is suitably the surface of any of these structures, such as metal, concrete, wood, organic polymers such as polyvinyl chloride or fiber-reinforced resins. Metal substrates, especially steel, aluminum or bronze substrates, are particularly suitable substrates. In another embodiment, the substrate is the surface of a flexible polymer carrier foil. Then, the coating composition is applied to one surface of the flexible polymer carrier foil (such as a polyvinyl chloride carrier foil) and cured, and subsequently the uncoated surface of the carrier foil is laminated to the surface of the structure to be provided with anti-fouling and / or fouling release properties, for example by using an adhesive.

[0075] To achieve good adhesion to the substrate, it is preferred to apply the fouling release coating composition to a substrate having a primer layer and / or an intermediate layer. The primer layer can be deposited from any primer composition known in the art, such as an epoxy resin-based or polyurethane substrate paint composition. More preferably, an intermediate layer deposited from an intermediate coating composition is provided for the substrate before applying the fouling release coating deposited from the fouling release coating composition of the present invention. The intermediate coating composition can be applied to the surface of the bare substrate, to the surface of the substrate still containing the coating composition of the aged layer, or to the surface of the substrate coated with a primer.

[0076] Intermediate coating compositions are known in the art. In a preferred embodiment, the intermediate layer is deposited from an intermediate coating composition comprising a binder polymer having an alkoxysilane functional group capable of reacting with the side alkoxys of the wet-curable polysiloxane (i), especially with the alkoxy O-R 6 reaction. This intermediate coating composition is known in the art, for example described in WO99 / 33927. The binder polymer having a curable alkoxysilane functional group in the intermediate coating composition can be any suitable binder polymer, such as polyurethane, polyurea, polyester, polyether, polyepoxy, binder polymers derived from ethylenically unsaturated monomers such as polyacrylate.

[0077] In one embodiment, the substrate is coated with a multi-layer coating system, including:

[0078] - Optionally, a primer layer applied to the substrate and deposited from a primer coating composition;

[0079] - An adhesion-promoting coating applied onto a substrate or onto an optional primer layer and deposited from an adhesion-promoting coating composition, said adhesion-promoting coating composition comprising a binder polymer having curable alkoxysilane functionality; and

[0080] - A topcoat layer applied onto the adhesion-promoting coating, said topcoat layer being deposited from a liquid soil-release coating composition according to the first aspect of the present invention.

[0081] The substrate onto which the primer layer is applied or, in the absence of a primer layer, onto which the adhesion-promoting coating is applied, may be a bare substrate surface or a substrate surface having an aged layer still containing a coating composition.

[0082] Preferably, the binder polymer in the adhesion-promoting coating composition is a polyacrylate having curable alkoxysilane functionality. The curable alkoxysilane functionality preferably has the following general formula:

[0083] -(C m H 2m )-Si(R 7 ) (3-n) (OR 8 ) n

[0084] wherein n is 1, 2 or 3, preferably 2 or 3; R 7 , R 8 are independently alkyl groups having 1-6 carbon atoms, preferably 1-4 carbon atoms, more preferably ethyl or methyl; m is an integer with a value of 1-20, preferably 1-6. More preferably, m is 1 or 3, even more preferably m is 1. It has been found that if m is 1, the adhesion between the adhesion-promoting coating and the soil-release coating deposited from the soil-release coating composition of the present invention is obtained faster than for values of m greater than 1. Soil

[0085] Preferably, the binder polymer in the adhesion-promoting coating composition does not have crosslinkable functionality other than alkoxysilane functionality.

[0086] In one embodiment, the binder polymer in the adhesion-promoting coating composition is prepared by free-radical polymerization of a mixture of acrylate and / or (meth)acrylate monomers, at least one of said monomers having alkoxysilane functionality, such as 3-(trimethoxysilylpropyl) methacrylate or trimethoxysilylmethyl methacrylate, preferably trimethoxysilylmethyl methacrylate. An example of such a monomer mixture is a mixture of methyl methacrylate, lauryl methacrylate and trimethoxysilylmethyl methacrylate.

[0087] Thus, in a third aspect, the present invention provides a method for controlling aquatic biofouling of an artificial object, comprising the following steps:

[0088] a) Apply a soil release coating composition according to the first aspect of the present invention to at least a portion of the surface of an artificial object;

[0089] b) Cure the coating composition to form a cured coating; and

[0090] c) Immerse the artificial object at least partially in water.

[0091] Preferably, the method further comprises the step of applying an adhesion coating deposited by the above adhesion coating composition to at least a portion of the surface of the artificial object before applying the soil release coating composition. Before applying the adhesion coating, the surface has a primer layer deposited by the above primer coating composition.

[0092] The adhesion coating composition is preferably the adhesion coating composition described above for the second aspect of the present invention.

[0093] In a last aspect, the present invention provides the use of a soil release coating composition according to the first aspect of the present invention for controlling fouling by aquatic organisms on an artificial object. Examples

[0094] Preparation of Resin A

[0095] Resin A is the reaction product of α,ω-dihydroxypolydimethylsiloxane and an excess of (N,N-dibutylaminomethyl)triethoxysilane. The preparation of this resin is described in Chinese Patent Application CN101134887A.

[0096] Preparation of the Coating Composition

[0097] The coating composition is prepared by high-speed dispersing the following components, where pbw means parts by weight.

[0098] Example 1 (Stain Release Coating Composition of the Present Invention)

[0099]

[0100]

[0101] After mixing, the composition can be used for at least 6 months when stored without exposure to atmospheric moisture.

[0102] Example 2 (Stain Release Coating Composition of the Present Invention)

[0103]

[0104] After mixing, the composition can be used for at least 6 months when stored without exposure to atmospheric moisture.

[0105] Example 3 (Stain Release Coating Composition of the Present Invention)

[0106]

[0107] After mixing, the composition can be stored for at least 6 months when stored without exposure to atmospheric moisture.

[0108] Examples A and B (comparative soil release coating compositions)

[0109]

[0110]

[0111] After mixing, the composition can be used for a maximum of 1 hour. After this time, the viscosity of the composition increases to a level that negatively affects the application and flow and leveling properties of the paint.

[0112] Preparation of an adhesion coating composition

[0113] Preparation of Adhesion Coating Composition 1

[0114] A siloxane-functional polyacrylate is prepared by copolymerizing a mixture of methyl methacrylate, lauryl methacrylate, and trimethoxysilylpropyl methacrylate in methyl n-amyl ketone (MAK) as a solvent at 100 °C in the presence of mercaptopropyltrimethoxysilane as a chain transfer agent and 2,2'-azobis(2-methylbutyronitrile) (AMBN) as an initiator. The molar ratio of methyl methacrylate / lauryl methacrylate / trimethoxysilylpropyl methacrylate / mercaptopropyltrimethoxysilane is 70 / 12 / 15 / 3. A 70 wt% solution of the polymer in MAK is obtained.

[0115] Preparation of Adhesion Coating Composition 2

[0116] A siloxane-functional polyacrylate is prepared as described above for acrylic adhesion coating composition 1, but with trimethoxysilylmethyl methacrylate replacing trimethoxysilylpropyl methacrylate.

[0117] Biological fouling testing

[0118] An Intershield 300 (International Paints Ltd) primer is applied to a marine-grade glued test panel to obtain an average dry film thickness of approximately 100 μm. Then, an Intersleek 731 silicone elastomer adhesion coating (International Paints Ltd) is applied to obtain an average dry film thickness of approximately 100 μm and the adhesion coating is allowed to dry. Then, the coating compositions of Example 1, Example 2, and Comparative Example A are applied to the pretreated panels at an average dry film thickness of approximately 150 μm.

[0119] The plate was then immersed in the aquatic environment at Changi Wharf in Singapore, a location known to experience severe marine fouling growth. After 74 weeks of immersion, the plates were evaluated to quantify the severity of animal fouling present. The results are shown in Table 1.

[0120] Table 1 - Coverage of animal fouling on the test coatings after 74 weeks of immersion

[0121]

[0122] Adhesion Test 1

[0123] A 12 x 6” steel plate was degreased with a solvent and then grit blasted to SA2.5. Then, Intersleek 717 Link Coat (International Paint Ltd) was applied as a primer coat to both sides by airless spraying, dried for 7 hours under indoor environmental conditions, and then Intersleek 737 silicone elastomer tie coat (International Paint Ltd) was applied to both sides by airless spraying. After drying for 1 day under indoor environmental conditions, one set of plates was coated on both sides with the coating composition of Example 1 by airless spraying, and a second set of plates was coated on both sides with the composition of Comparative Example A by airless spraying. Then, the test plates were immediately moved to an external area and exposed to ambient outdoor conditions in northeast England for 48 hours.

[0124] The adhesion of the final coating to the previous coating was qualitatively evaluated by making a first 5 cm incision through the coating down to the steel substrate using a utility knife blade, and then cutting a second 5 cm incision across the first incision to form an “X” shape. The intersection of the incisions was rubbed with a finger, and the relative difficulty of the final coating peeling away from the previously applied coating was observed. This allowed the adhesion of the different final coatings to be scored.

[0125] The coating prepared from Comparative Composition A was more likely to peel away from the previously applied coating compared to the coating prepared from Coating Composition 1 of the present invention. This demonstrates that the coating composition of Example 1 provides better adhesion than Comparative Composition A.

[0126] Adhesion Test 2

[0127] Roughen the surface of a 6 x 4” aluminum Q-panel using sandpaper and then degrease it with a solvent. Then brush on Adhesion Coating Composition 1 or Adhesion Coating Composition 2 on both sides of the panel. After drying for 1 day under indoor environmental conditions, brush on the coating composition of Example 3 on both sides of one set of panels and brush on the comparative coating composition of Example B on both sides of a second set of panels. Then, immediately move the test panels to an external area and expose them to ambient outdoor conditions for 96 hours in the winter in northeast England.

[0128] After 5, 24, and 96 hours of exposure, qualitatively evaluate the adhesion of the final coating to the adhesion coating by cutting and removing a small piece of the coating down to the substrate using a utility knife blade. Rub the exposed portion with a finger and give a score of 0 (poor adhesion) to 5 (very good adhesion) for the adhesion between the adhesion coating and the topcoat.

[0129] Table 2 Adhesion between the adhesion coating and the soil release coating

[0130]

[0131]

[0132] It can be generalized that, compared with the comparative coating composition, the soil release coating composition of the present invention can be used for a longer time (longer pot life) after mixing and provides a coating with improved antifouling performance and better adhesion.

Claims

1. A non-aqueous liquid fouling release coating composition for controlling aquatic biofouling on an artificial object, comprising: i) A moisture-curable polysiloxane comprising repeating units of formula (I) and at least one end group or side group of formula (II): wherein R 1 and R 2 are independently organic groups having 1 to 20 carbon atoms; R 3 and R 4 are independently organic groups having 1 to 20 carbon atoms; A is an organic group having 1 to 50 carbon groups; R 5 is independently selected from organic groups having 1 to 20 carbon atoms and groups of the formula O-R 6 wherein R 6 is an organic group having 1 to 20 carbon atoms, provided that at least one R 5 is a group of the formula O-R 6 and ii) at least one marine biocide or a non-volatile component comprising units selected from hydrocarbyl, heterohydrocarbyl, halohydrocarbyl, ether, ester, amide, ketone, siloxane, carbamate or urea groups.

2. The fouling release coating composition according to claim 1, wherein the coating composition further comprises an aminosilane of formula (III): wherein R 3 -R 5 and A are as defined in claim 1, and wherein at least one R 5 is a group of the formula O-R 6 wherein R 6 is an organic group having 1 to 20 carbon atoms.

3. The fouling release coating composition according to claim 1 or 2, wherein component ii) does not contain groups of formula (II).

4. The fouling release coating composition according to any one of the preceding claims, wherein A is a methylene group.

5. The soil release coating composition according to any one of the preceding claims, wherein R 1 and R 2 are each independently methyl or phenyl.

6. A soil release coating composition according to any one of the preceding claims, wherein R 5 is selected from C 1 -C 4 alkoxy groups, preferably ethoxy groups.

7. The fouling release coating composition according to any one of the preceding claims, wherein the coating composition is substantially free or completely free of marine biocides.

8. The fouling release coating composition according to any one of the preceding claims, wherein the coating composition comprises a volatile organic solvent.

9. The antifouling coating composition according to any one of the preceding claims, wherein the non-volatile content is 70 - 100 wt%.

10. A substrate coated with the fouling release coating composition according to any one of the preceding claims.

11. The substrate according to claim 10, wherein the substrate is coated with a multi-coating system, the multi-coating system comprising: - Optionally, a primer layer applied to the substrate and deposited by a primer coating composition; - An intermediate coating applied to the substrate or to the optional primer layer and deposited by an intermediate coating composition, the intermediate coating composition comprising a binder polymer having curable alkoxysilane functional groups; and - A topcoat layer applied to the intermediate coating, the topcoat layer being deposited by the liquid fouling release coating composition according to any one of claims 1 - 9.

12. The substrate according to claim 10 or 11, wherein the intermediate coating composition comprises a polyacrylate having curable alkoxysilane functional groups.

13. A method for controlling aquatic biofouling on an artificial object, comprising the steps of: a) Applying the fouling release coating composition according to any one of claims 1 - 9 to at least a portion of the surface of the artificial object; b) Curing the coating composition to form a cured coating; and c) Immersing the artificial object at least partially in water.

14. The method according to claim 13, further comprising the step of applying an intermediate coating deposited by the intermediate coating composition according to claim 11 or 12 to at least a portion of the surface of the artificial object before applying the fouling release coating composition.

15. Use of the fouling release coating composition according to any one of claims 1 - 9 for controlling aquatic biofouling on an artificial object.

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