Composition of antifouling coating and antifouling coating

Abstract

Antifouling Coating Composition and Antifouling Coating The present invention relates to a composition for forming an antifouling coating, comprising a sol-gel, at least one solvent for the sol-gel, in particular at least one inorganic or organic solvent, or a mixture of at least one organic solvent and at least one inorganic solvent, and graphene or graphene oxide. The composition does not contain any biocide. It also relates to an antifouling coating, formed from a sol-gel binder layer containing graphene or graphene oxide, as well as any substrate coated with such an antifouling. Figure for the abstract: none

Description

Title of the invention: Antifouling coating composition and antifouling coating

[0001] The present invention relates to a novel composition for forming an antifouling coating, not requiring a biocide. The invention also relates to the antifouling coating (or antifouling), formed on the surface of a support, as well as the support thus coated and protected and any device, apparatus, material, floating or bottom-mounted building (navigating or non-navigating building, on fresh or salt water, which includes inland navigation vessels, including small boats and ferries, as well as floating craft and sea vessels, oil platforms, piles and beacons, etc.), comprising such a structure (the support being for example a hull, a propeller, a rudder, a pillar, a chain, etc.).

[0002] In water, depending on the region of the globe and the season, more than 25,000 species of living organisms capable of colonizing boat hulls have been identified: bacteria, unicellular algae, green algae, barnacles, sponges, marine worms, etc. Biofouling, also known as "fouling," is a common problem encountered by boat owners and marine operators. It refers to the accumulation of these marine organisms on the hull of ships and other submerged surfaces. Although it may seem like a minor aesthetic inconvenience, fouling can lead to many significant problems and risks. Increased water resistance: Biofouling on the hull increases water resistance, which leads to increased fuel consumption and reduces the energy efficiency of the vessel.This can lead to additional fuel costs and a decrease in overall speed and performance. Reduced maneuverability: The accumulation of fouling on rudders and propellers can lead to a decrease in the maneuverability and controllability of the vessel. This can increase the risk of collisions and dangerous situations, especially in areas with high vessel traffic density. Property damage: Marine organisms can cause physical damage to the vessel's hull, cooling systems, seawater intakes, propellers, and other submerged parts. This damage can require costly repairs and lead to unplanned downtime.

[0003] The current solution is the use of so-called "antifouling" paints, but these have drawbacks. Risks for the marine ecosystem: traditional antifouling paints contain biocides which are used to kill marine organisms and thus prevent their adhesion. Among the usual biocides, we can cite as an illustration the following compounds: copper thiocyanate, zinc ethylene bisdithiocarbamate, zinc pyrithione, medetomidine, copper oxide. However, these biocides dissipate in water and have a detrimental impact on the marine ecosystem, affecting aquatic flora and fauna. Impact on human health: Some biocides used in traditional antifouling products can also pose risks to human health, particularly for people working on ships or in shipyards where these products are handled. Therefore, the use of biocide-free antifouling products would offer a more environmentally friendly and safer alternative for ships, operators, and the marine ecosystem.

[0004] The invention therefore aims to propose a composition intended to form an antifouling coating, generating an effective antifouling effect in the absence of biocide, which is capable of limiting or preventing biological fouling of an immersed surface for a long period, in particular greater than 6 months or even for one or more years.

[0005] Another objective of the invention is to propose such a composition which is easy to implement and which is non-toxic both during its manufacture, its application to a surface such as a ship's hull, during its submerged life, and then during the reprocessing of this surface when it is decided to repeat the treatment.

[0006] Yet another objective of the invention is to provide such a composition which can be applied both to a new surface and to a surface which has previously received an antifouling treatment of another type.

[0007] Yet another objective of the invention is to provide such a composition which has an acceptable operating cost.

[0008] The subject of the present invention is a composition intended to form an antifouling coating, comprising a sol-gel, at least one solvent or diluent of the sol-gel, in particular at least one inorganic solvent, or at least one organic solvent, or a mixture of at least one organic solvent and at least one inorganic solvent, and graphene or graphene oxide. Advantageously, the composition does not comprise a biocide or additive with biocidal activity, it is a “biocide-free composition”, in particular without any of the usual biocides listed above.

[0009] Without wishing to be bound by theory, it is believed that the composition according to the invention makes it possible to produce a coating which limits or prevents biological fouling by an essentially anti-adherent effect, the living organisms not being able to attach themselves effectively and durably to the coating produced, which limits their attachment to the coating or allows easy removal of organisms which have attached themselves in a weak or weak manner, this removal being able to be carried out for example by brushing or by mechanical rubbing, or being able to occur naturally under the effect of friction with water during the movement of a boat, ship or boat.

[0010] For the purposes of the present invention, the term "composition intended to form an antifouling coating" means a composition intended to be applied to an element or surface that can or must be immersed in water. This particularly concerns an application to the submerged part of ships, boats, vessels of all kinds, underwater (for example on all or part of the hull, the keel, the propeller) or to the submerged part of a building resting on the bottom or of a building or apparatus attached to the bottom. The treatment aims to prevent, delay, or facilitate the elimination of biological fouling, also called "fouling deposit", consisting of aquatic organisms, including algae and molluscs, capable of attaching, forming, growing and spreading on these submerged surfaces.The composition of the invention can be applied like a conventional paint, for example with a brush or roller, using a microfiber cloth or a sponge, or by spraying, or any other means of painting. The composition can be deposited on a pre-existing layer of paint or antifouling or on a new element that is not coated or includes at least one undercoat.

[0011] The composition intended to form an antifouling coating may in particular comprise from approximately 0.01 to approximately 5%, more particularly from approximately 0.1 to approximately 1, 2 or 3% by weight of graphene or graphene oxide, relative to the total weight of the composition.

[0012] The graphene or graphene oxide used may in particular be in the form of a sheet and / or a stack of several sheets, in particular from 2 to 10 sheets, forming what are called platelets. The maximum dimensions of the platelets may vary in certain proportions ranging in particular from 1 to 100 μm, preferably from 5 to 20 μm. The graphene may also be in the form of nanowires or nanotubes preferably having these same maximum dimensions. By "maximum dimensions" is meant the greatest length of an element or unit of graphene or graphene oxide. These reduced dimensions are preferred because they promote a situation in which the graphene or graphene oxide is embedded in the coating, and / or graphene units may be exposed on the surface, but without there being a high proportion of units protruding outside the coating, likely to be torn off.

[0013] The graphene used can be obtained by well-known production methods, such as mechanical exfoliation, solution chemistry or vapor phase growth, under conditions allowing the production of graphene having the aforementioned dimensions. Calibration can be carried out to ensure that the wafers used have the structures and dimensions suitable for the invention.

[0014] The composition contains one or more solvents in sufficient proportion so that the composition is sufficiently fluid to be applied to the substrate. In particular, the proportion of solvent by weight relative to the total weight of the composition is between about 20 and about 90%, preferably between about 20 and about 70%.

[0015] The addition of the sol-gel and the graphene or graphene oxide represents a dry extract called ES. The composition may therefore in particular have a dry extract ES of between approximately 10 and approximately 60%, in particular between approximately 10 and approximately 50, preferably between approximately 30 and approximately 45 or 50%.

[0016] The sol-gel is preferably silicon-based. It is obtained by mixing and reacting at least two organosilicon precursors in a solvent. The polymerization of these precursors creates the sol-gel. These organosilicon precursors are notably silicon alkoxides.

[0017] As is known per se, a sol-gel material is a material obtained by a sol-gel process consisting of using as precursors metal alkoxides of formula Si(OR)xR'(4 x) where R is an alkyl group (in particular C1 to C20) and R' is a group carrying one or more functions, for example aryl, alkyl, with x being able to vary between 2 and 4. In the presence of water, the alkoxyl groups (OR) are hydrolyzed into silanol groups (Si-OH). The latter condense by forming siloxane bonds (Si-O-Si-). Small particles are formed, generally less than 1 μm in size, which aggregate and form clusters which remain in suspension without precipitating, forming a sol. The increase in the clusters and their condensation increases the viscosity of the medium which gradually gels. A porous solid material is finally obtained by drying the gel, with the expulsion of the solvent outside the formed polymer network (syneresis).

[0018] The sol-gel in the composition remains sufficiently diluted in solvent so that the composition can be handled and applied like a varnish or paint. The quantities of the different ingredients (sol-gel, solvent, graphene or graphene oxide, and any additives) are therefore adjusted accordingly.

[0019] The organosilicon precursor used in the coating composition may consist of a single organosilicon precursor or a mixture of several (at least two) organosilicon precursors. The precursor(s) are advantageously chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), methyltrimethoxysilane (MTM), methyltriethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhTEOS), a chloroalkylmethoxysilane or a chloroalkylethoxysilane (in which the alkyl is C1 to C10, preferably ethyl, methyl or propyl), an aminopropyltriethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMOS) and mixtures thereof.

[0020] More particularly, the organosilicon precursor(s) are chosen from tetra- methoxysilane (TMOS), tetraethoxysilane (TEOS), methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhTEOS), (3-aminopropyl)triethoxysilane (APTES), (3-glycidyloxypropyl)trimethoxysilane (GPTMOS) and mixtures thereof.

[0021] Preferably, the organosilicon precursor(s) are chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), methyl trimethoxysilane (MTM), phenyltrimethoxysilane (PhTMOS), (3-aminopropyl)triethoxysilane (APTES), (3-glycidyloxypropyl)trimethoxysilane (GPTMOS) and mixtures thereof.

[0022] In embodiments, the composition comprises tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), or a mixture of TMOS and TEOS.

[0023] The composition comprises one or more organic solvents, one or more inorganic solvents or a mixture of organic solvent(s) and inorganic solvent(s). An inorganic solvent may be water. The organic solvent is in particular polar, protic or aprotic. This organic solvent may for example be chosen from linear aliphatic alcohols C1 to C4, in particular methanol, ethanol, propan-2-ol, and propan-1-ol; or glycol ethers, in particular di-propylene glycol methyl ether (DGME), propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether. Preferably, the organic solvent is isopropanol (propan-2-ol), DGME or a mixture of isopropanol and DGME.In the case of an aqueous solvent, this advantageously contains from 50% to 100% by volume of water.

[0024] A possible mixture of organic solvents is the mixture of isopropanol and DGME. When DGME is used as a solvent in a mixture of solvents, the composition may comprise in particular from about 50 to about 80%, preferably from about 70 to about 80%, by weight of DGME, relative to the total weight of the composition. In a mixture of solvents, for example DGME and another solvent, for example isopropanol, this other solvent may in whole or in part come from the manufacture of the sol-gel, and the DGME is a solvent added during the formulation of the composition. Note that this may apply to a solvent other than DGME. This solvent added during the formulation is called a dilution solvent.

[0025] In one embodiment the composition contains a single organic solvent, for example DGME, in the proportions defined above.

[0026] The presence in addition of one or more other binders, preferably inorganic, but also organic, such as epoxy resins, acrylic polymers, polyurethane resins, etc., in a proportion of 1 to 30% of dry polymers relative to the total weight of the composition.

[0027] The composition according to the invention may also contain one or more other additives, preferably environmentally acceptable, chosen from pigments (e.g. iron oxide), mineral fillers (e.g. calcium carbonate, talc, aerogel), wetting agents (e.g. pine oil), dispersing agents (e.g. polycarboxylates), anti-sedimentation agents (e.g. celluloses) and plasticizing agents, anti-foaming agents (e.g. mineral or silicone oil), allowing the deaeration of the coating in the pot but also during application.

[0028] The composition according to the invention may comprise in particular from 0 to 40%, in particular from 0.01 to 30% by weight of one or more additives relative to the total weight of the composition.

[0029] According to a particular embodiment of the invention, the composition may comprise, relative to the total weight of the composition: a. from 60 to 100% by weight of the sol-gel + solvent mixture (in particular DGME, said composition containing from 10 to 45 or 48% by weight of sol-gel in dry extract, b. from 0.01 to 2% by weight of graphene or graphene oxide c. from 0 to 30% by weight of one or more of the above additives.

[0030] The siliceous sol-gel used in this invention can be prepared by a conventional sol-gel process, involving the conversion of the organosilicon precursor into a gelled three-dimensional network. The siliceous sol-gel is then combined with graphene, optionally with suitable polymeric components to form the anti-fouling coating, such as epoxy resins, acrylic polymers, polyurethane resins.

[0031] The application can be carried out like a conventional painting, for example by brush or roller, using a microfiber cloth or a sponge, or by spraying, on the surface to be treated, bare or bearing a pre-existing layer of paint or antifouling. It is then left to dry to obtain the dried and hardened coating. Drying can be carried out in the open air so as to form a dry and hardened antifouling layer. Drying can be forced using appropriate means.

[0032] The present invention also relates to an antifouling coating, formed from a sol-gel type binder layer containing graphene or graphene oxide. This coating is free of biocide or additive with biocidal activity; it is a “biocide-free” coating, like the composition from which it is derived. This coating can in particular be obtained by applying and drying the composition according to the invention intended to form an antifouling coating.

[0033] In particular, the coating formed solely from sol-gel and graphene produces a transparent varnish.

[0034] The antifouling coating according to the invention is relatively thin, with in particular a thickness after drying of approximately 5 to approximately 150 μm, in particular of approximately 5 to approximately 120 μm.

[0035] In one embodiment, the antifouling coating according to the invention has a thickness after drying of approximately 5 to approximately 120 μm, in particular of approximately 5 to approximately 30 μm, preferably of approximately 5 to approximately 20 μm. This coating has in particular been obtained from a composition containing no or few additives of the pigment and filler type. In particular, this coating is transparent, it is a transparent varnish.

[0036] This coating may be single-layer, forming a single layer on the substrate.

[0037] It may also be part of a two-layer assembly, or at least two-layer assembly, in particular when a colored layer is provided in addition to this first coating. In this case, a composition intended to form the antifouling coating is used which additionally comprises one or more pigments or dyes. This colored layer is intended to provide opacity and coloring. It is preferably formed first, then covered with the transparent varnish. Its thickness after drying may be from approximately 70 to approximately 150 μm, in particular from approximately 90 to approximately 120 μm.

[0038] It is also possible to deposit a single composition containing pigment or colorant, to form a colored varnish as an antifouling coating. This layer provides opacity and coloring. Its thickness after drying can be from about 70 to about 150 μm, in particular from about 90 to about 120 μm.

[0039] The invention also relates to any support, surface or article coated with such an antifouling coating, formed from a sol-gel type binder layer containing graphene or graphene oxide. This coating is free of biocide or additive with biocidal activity. This coating can in particular be obtained by applying and drying the composition intended to form an antifouling coating, according to the invention. This coating can have the composition characteristics resulting from the composition used, described here.

[0040] Among the supports capable of receiving the antifouling of the invention, mention may in particular be made of metals (e.g. steel, galvanized, aluminum, stainless steel, zinc, brass), polymers (e.g. epoxy, polyurethane, acrylic, vinyl).

[0041] The composition of the invention can be applied directly in contact with this support, or on a material totally or partially covering this support. There is no limitation to the material of the support, the person skilled in the art can easily test the ability of the composition according to the invention to adhere durably to any material. It is furthermore possible to provide a layer of bonding or pretreatment material, for example when the support is made of polytetrafluoroethylene (PTFE), polyethylene (PE) or polypropylene (PP). As pretreatment, mention may be made of heat treatment, particularly by plasma.

[0042] The support, surface or article coated with an antifouling coating according to the invention may belong to any device, apparatus, or material, likely to remain in contact with fresh water or salt water. It may be, for example, a floating, underwater building, or one placed on the bottom (a building navigating or not, on fresh or salt water, which includes inland navigation vessels, including small boats and ferries, as well as floating craft and sea vessels, oil platforms, installations for pumping or extracting liquid or gas, piles and beacons, etc.). The treated surface may be, for example, a hull, a propeller, a rudder, a pillar, a chain, etc.

[0043] Preferably, the surface is a surface of a ship intended to be immersed in water, such as the hull or keel of a ship.

[0044] The present invention also relates to such a device, apparatus, or material, comprising a surface or an element coated, totally or partially, with an antifouling layer according to the invention.

[0045] The particularity of the antifouling according to the invention is that it forms a continuous and resistant film, with a remarkably long durability, in particular greater than 6 months, and more precisely greater than or equal to 1, 2, 3, 4 or 5 years.

[0046] Siliceous sol-gel is an amorphous inorganic material derived from silica, which here provides excellent non-stick properties, to which are added the non-stick properties of graphene or its oxide. This joint presence makes it possible to obtain an effective antifouling coating to prevent the strong attachment and growth of undesirable marine organisms on submerged surfaces.

[0047] The coating also provides a slipperiness in the water, which allows a vessel to move more quickly on or under water.

[0048] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example.

[0049] Example 1:

[0050] A colorless composition according to the present invention has the following composition: [Table 1] dipropylene glycol methyl ether 44.3 g Sol gel 20 g Graphene 2g

[0051] The sol-gel is obtained from tetramethoxysilane and tetraethoxysilane, by hydrolysis of the triethoxysilyl functionalities [-Si(OEt)3].

[0052] Graphene is in the form of platelets 1 to 4 nm thick, comprising 2 to

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[0059]

[0060] 8 leaflets, and 7.5 ± pm in the largest dimension (note that the leaflets are approximately square). This composition produces a transparent varnish. It was used to form an antifouling coating on a motorboat hull of length 9.3 m, width 3.2 m and height 1 m. The following layers were made, in this order: - Primer: 5-coat solvent-based epoxy coating of 100 µm dry film thickness; - Base coat: solvent-based epoxy coating (two-component) 1 coat, dry film thickness 100 µm; - Finishing the hull: the antifouling sol-gel coating resulting from the application and drying of the composition in Table 1: application of the composition with a microfibre cloth in 1 layer, dry film thickness between 5 and 8 pm. The antifouling sol-gel coating helps prevent visible biological fouling in seawater. The same composition was used on the hull of an old wooden boat. The hull, initially encrusted with a significant amount of biofouling on the bottom and mucilage on the sides, was cleaned with low-pressure water, all the biomass was removed, before being repainted. It was then given a layer of the sol-gel antifouling coating according to Example 1, using a microfiber cloth. The antifouling sol-gel coating helps prevent visible biological fouling in fresh water. Example 2: A colored composition according to the present invention has the following composition: [Table 2] Dipropylene glycol methyl ether 77 g Sol gel according to example 1 20 g Graphene according to example 1 2 g Calcium carbonate 20 g Pine oil 1.2 g Spreading agent: polycarboxylate 0.5 g Iron oxide 10 g Deaerating agent: silicone or mineral oil 1 g This composition is used as an undercoat for the transparent coating in the example 1.

[0061] This composition is also used in a thicker layer as a single anti-fouling layer.

[0062] Example 3:

[0063] A colorless composition according to the present invention has the following composition: [Table 3] dipropylene glycol methyl ether 44.3 g Sol gel of example 1 20 g Graphene of example 1 2 g Pine oil 1.2 g

Claims

Claims

1. A composition for forming an antifouling coating, comprising a sol-gel, at least one solvent for the sol-gel, and graphene or graphene oxide.

2. Composition according to claim 1, characterized in that it is free from biocide.

3. Composition according to claim 1 or 2, characterized in that it comprises from 0.01 to 5%, more particularly from 0.1 to 2% by weight of graphene or graphene oxide relative to the total weight of the composition.

4. Composition according to any one of claims 1 to 3, characterized in that the sol-gel and the graphene or graphene oxide represent in the composition a dry extract of between 10 and 60%, in particular between 10 and 50, preferably between 30 and 50%.

5. Composition according to any one of claims 1 to 4, characterized in that the sol-gel is obtained from an organosilicon precursor chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), methyl trimethoxysilane (MTM), methyl triethoxysilane (MTE), phenyltrimethoxysilane (PhTMOS), phenyltriethoxysilane (PhTEOS), a chloroalkylmethoxysilane or a chloroalkylethoxysilane with a C1 to C10 alkyl, an aminopropyltriethoxysilane, such as preferably (3-aminopropyl)triethoxysilane (APTES), (3-glycidyloxypropyl)trimethoxysilane (GPTMOS), and mixtures thereof.

6. Composition according to any one of claims 1 to 5, characterized in that the solvent comprises an organic solvent, an inorganic solvent, or a mixture of organic solvent and inorganic solvent, the organic solvent preferably being chosen from linear C1 to C4 aliphatic alcohols, in particular methanol, ethanol, propan-2-ol, and propan-1-ol; or glycol ethers, in particular dipropylene glycol methyl ether (DGME), propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether.

7. Composition according to any one of claims 1 to 6, ca- characterized in that the proportion of solvent by weight relative to the total weight of the composition is between 20 and 90%, preferably between 20 and 70%.

8. Antifouling coating, formed from a sol-gel type binder layer containing graphene or graphene oxide.

9. Antifouling coating according to claim 8, characterized in that it is free from biocide.

10. Antifouling coating according to claim 8 or 9, characterized in that it has a thickness of about 5 to about 150 μm, in particular of about 5 to about 120 μm.

11. Antifouling coating according to any one of claims 8 to 10, characterized in that it results from the application and drying of a composition according to any one of claims 1 to 7.

12. Support, surface or article coated with a coating according to any one of claims 8 to 11, the support, surface or article belonging to a device, apparatus, or material, capable of remaining in contact with fresh water or salt water.