Environment-friendly copper-free marine antifouling coating and preparation method thereof

Abstract

This invention belongs to the field of new materials and discloses an environmentally friendly, copper-free marine antifouling coating, comprising the following parts by weight: 20-50 parts of modified acrylic resin; 10-30 parts of graphene-coated manganese oxide composite material; organic solvents and additives. This coating uses modified acrylic resin and graphene-coated manganese oxide as the main raw materials. The graphene coating of manganese oxide slows down the oxidation rate of manganese oxide, while the modified acrylic resin protects the graphene-coated manganese oxide and provides the paint film with better adhesion, hardness, and gloss, significantly improving the service life and antifouling ability of the paint film. Furthermore, this invention also provides a method for preparing this coating.

Description

Technical Field

[0001] This invention relates to the field of new materials, specifically to an environmentally friendly copper-free marine antifouling coating and its preparation method. Background Technology

[0002] Algae, barnacles, and shellfish in the ocean can attach to ships, increasing the roughness of the hull surface and thus increasing fuel consumption. At the same time, the attached organisms produce acidic substances that corrode the hull during their growth and metabolism, reducing the hull's lifespan and causing serious negative impacts on the economy and production safety.

[0003] Antifouling coatings are the most economical and efficient means of preventing marine biofouling, evolving from early organotin antifouling coatings to today's self-polishing antifouling coatings containing cuprous oxide. Organotin antifouling coatings are highly toxic to marine organisms and were completely banned in 2008. Cuprous oxide antifouling agents are ineffective against algae such as *Ulva prolifera*, *Senecio scandens*, and *Cyclocarya paliurus*, and the large amounts of copper oxide exacerbate marine pollution. Modified manganese oxide antifouling agents, however, have a large specific surface area, uniform particle size, high purity, low cost, low bioaccumulation, and are environmentally friendly, making them an ideal marine biofouling agent.

[0004] In the existing technology, there are no successful cases of applying manganese oxide to marine antifouling coatings. Summary of the Invention

[0005] The purpose of this invention is to provide an environmentally friendly, copper-free marine antifouling coating. This coating uses modified acrylic resin and graphene-coated manganese oxide as the main raw materials. The graphene coating of manganese oxide can slow down the oxidation rate of manganese oxide. At the same time, the modified acrylic resin protects the graphene-coated manganese oxide and provides the paint film with better adhesion, hardness and gloss, which significantly improves the service life and antifouling ability of the paint film.

[0006] In addition, the present invention also provides a method for preparing the coating.

[0007] To achieve the above objectives, the present invention provides an environmentally friendly, copper-free marine antifouling coating, comprising the following components by weight:

[0008] 20-50 parts of modified acrylic resin;

[0009] 10–30 parts of graphene-coated manganese oxide composite material;

[0010] Organic solvents and additives.

[0011] In the aforementioned environmentally friendly copper-free marine antifouling coating, the additives are pigments, fillers, antisettling agents, dispersants, and defoamers;

[0012] The dosage of each auxiliary agent is as follows:

[0013]

[0014] The amount of organic solvent used is 10 to 40 parts.

[0015] In the above-mentioned environmentally friendly copper-free marine antifouling coating, the pigments and fillers are two or more of the following: iron oxide red, organic red, talc powder, mica powder, barium sulfate, calcium carbonate, kaolin, and lithopone.

[0016] The anti-settling agent is bentonite, attapulgite, and polyamide wax, etc.

[0017] The dispersant is one or two of the modified polyacrylate polymer and modified polyurethane polymer. Preferably, the dispersant is one or more of BYK2150, BYK-108, BYK-108, AFCONA-4010, AFCONA4077, AFCONA-4400, AFCONA4550, and AFCON-4570.

[0018] The defoamer is one or two of the following: organosilicon polymer, fluorocarbon-modified organosilicon polymer, vinyl polymer, and fluorocarbon-modified vinyl polymer. Preferably, the defoamer is one or more of the following: BYK-066N, BYK-052N, BYK-8800, AFCONA-2022, AFCONA-2040, and AFCONA-2048.

[0019] The organic solvent is one or more of the following: methyl ethyl ketone, butanone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, propylene glycol methyl ether acetate, isopropanol, n-butanol, toluene, and xylene.

[0020] In the aforementioned environmentally friendly copper-free marine antifouling coating, the modified acrylic resin is obtained by free radical solution polymerization of monomers, wherein the monomers include acrylic acid, acrylate monomers, fluorinated acrylate monomers, acrylonitrile, and unsaturated monomers with epoxy groups; the mass ratio of acrylic acid, acrylate monomers, fluorinated acrylate monomers, acrylonitrile, and unsaturated monomers with epoxy groups is 10-30:50-100:3-5:5-10:1-5.

[0021] The modified acrylic resin of the present invention was modified with fluorinated acrylate monomers, acrylonitrile, and unsaturated monomers with epoxy groups;

[0022] During the research and development process, we found two problems when conventional acrylic resins were applied to this invention: weak resistance to bioaccumulation and easy damage to the coating film in harsh environments. The former is related to the easy oxidation of manganese oxide and whether the coating itself has resistance to bioaccumulation. The latter is not only related to the performance of the resin itself, but also to the compatibility and dispersibility of the resin and graphene coating.

[0023] Specifically:

[0024] Regarding the resistance to bioaccumulation, this invention employs graphene-coated manganese oxide, which prevents the manganese oxide from being oxidized and deactivated through the graphene layer on the surface of the manganese oxide particles. At the same time, this invention uses fluorinated acrylate monomers to modify acrylic resin, which can be used to improve the resin's resistance to bioaccumulation.

[0025] In terms of weather resistance, this invention uses fluorinated acrylate monomers and unsaturated monomers with epoxy groups to modify acrylic resin, improve the affinity between resin and graphene oxide, improve the dispersion uniformity and stability of graphene oxide in resin, thereby improving the overall strength of the paint film and maintaining the integrity of the paint film in harsh experimental environments.

[0026] Among them, unsaturated monomers with epoxy groups serve as comonomers for acrylic resins. They provide epoxy groups to the resin, which have two functions: one is to open the ring during polymerization, providing crosslinking sites; the other is to react with some hydroxyl groups present on the graphene surface. These hydroxyl groups exist as nucleophiles, and the epoxy groups exist as electrophiles, undergoing a ring-opening reaction, allowing the epoxy groups to covalently bond with the graphene surface. Fluorinated acrylate monomers, based on the hydrophobic properties of graphene itself, achieve surface affinity through non-covalent contact between the fluorinated groups and the graphene surface. Through the above two forms of covalent and non-covalent bonding, the dispersion uniformity of graphene-coated manganese oxide in the resin is improved.

[0027] Meanwhile, acrylonitrile improves the scratch resistance of the resin and coating, while fluorinated acrylate monomers and acrylonitrile can also improve the resin's anti-aging ability, maintain the tightness of the coating, and reduce the aging risk of manganese oxide. In the modified acrylic resin of this invention, the reasonable matching of acrylate and acrylic acid can improve the flexibility and peel strength of the coating.

[0028] In the aforementioned environmentally friendly copper-free marine antifouling coating, the mass ratio of acrylic acid, acrylate monomers, fluorinated acrylate monomers, acrylonitrile, and unsaturated monomers with epoxy groups is 15-25:50-100:3-5:6-9:2-4.

[0029] In the aforementioned environmentally friendly copper-free marine antifouling coating, the acrylate monomers are one or more combinations of methyl acrylate, ethyl acrylate, methyl methacrylate, and propyl acrylate; the fluorinated acrylate monomers are trifluoroethyl acrylate and / or hexafluorobutyl acrylate.

[0030] In the aforementioned environmentally friendly copper-free marine antifouling coating, the unsaturated monomer with epoxy groups is one or more combinations of vinyl glycidyl ether, glycidyl acrylate, and allyl alcohol glycidyl ether.

[0031] In the above-mentioned environmentally friendly copper-free marine antifouling coating, the modified acrylic resin is prepared by adding acrylic acid, acrylate monomers, fluorinated acrylate monomers, acrylonitrile, and unsaturated monomers with epoxy groups into a solvent, heating to reflux temperature under an inert gas atmosphere, adding a portion of initiator, reacting for 4-8 hours, and then adding the remaining initiator to eliminate the monomers and keeping warm for 1-2 hours.

[0032] The weight ratio of the solvent to all monomers is 100-200:100; the solvent is one or more combinations of toluene, xylene, n-butanol, N,N-dimethylacetamide, and butyl acetate; the initiator is azobisisobutyronitrile or benzoyl peroxide; the amount of the initiator is equivalent to 1.5-4 wt% of the total amount of all monomers.

[0033] In the aforementioned environmentally friendly copper-free marine antifouling coating, the graphene-coated manganese oxide composite material is composed of manganese oxide and graphene coated on the outer surface of manganese oxide.

[0034] The D50 particle size of the manganese oxide is 10–40 μm; the D50 sheet size of the graphene is 0.1–0.9 μm.

[0035] The weight ratio of manganese oxide to graphene is 100:10 to 20.

[0036] Finally, this invention also discloses a method for preparing an environmentally friendly copper-free marine antifouling coating as described in any of the above descriptions, comprising the following steps:

[0037] Step 1: Disperse the graphene-coated manganese oxide composite material in an organic solvent;

[0038] Step 2: Mix the pre-dispersed additives and modified acrylic resin in an organic solvent with the mixture obtained in Step 1.

[0039] The beneficial effects of this invention are: it uses modified acrylic resin and graphene-coated manganese oxide as the main raw materials. The graphene coating of manganese oxide can slow down the oxidation rate of manganese oxide. At the same time, the modified acrylic resin protects the graphene-coated manganese oxide and provides the paint film with better adhesion, hardness and gloss, which significantly improves the service life and anti-pollution ability of the paint film. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments. It should be noted that the following embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0041] Part 1: Preparation of Modified Acrylic Resin

[0042] The preparation method of modified acrylic resin includes the following steps:

[0043] Step 1: Add acrylic acid, acrylate, fluorinated acrylate monomers, acrylonitrile, and unsaturated monomers with epoxy groups into the reactor. Then add 125g of toluene and 25g of n-butanol to the reactor and purge the air from the reactor with nitrogen for 5 minutes.

[0044] (2) Raise the temperature of the reactor to 100°C.

[0045] (3) Mix 50g of toluene, 25g of n-butanol and 3g of azobisisobutyronitrile evenly and place them in a constant pressure funnel. Add the mixture to the reaction vessel at a rate of 2 drops per second and react for 6 hours.

[0046] (4) Continue to add 1g of azobisisobutyronitrile to the reactor and keep it warm for 2 hours.

[0047] (5) After the reaction is complete, cool the reactor to room temperature, discharge the material, filter it, and package it.

[0048] The dosage and types of monomers used in step 1 can be found in Table 1 below;

[0049] Table 1 Formula Table (Unit: g)

[0050]

[0051] Part Two: Preparation of Graphene-Coated Manganese Oxide Composite Materials

[0052] This invention is prepared using a wet coating method, specifically including the following steps:

[0053] Step 1: Disperse graphene in water and sonicate for 5 minutes to form a 1 wt% graphene dispersion;

[0054] Step 2: Add manganese oxide and coupling agent to the graphene dispersion from Step 1, and mix for 20 minutes with stirring assistance; the coupling agent is KH550, which is equivalent to 0.1 wt% of the weight of manganese oxide.

[0055] Step 3: Filter the solution obtained in Step 2, wash it with anhydrous ethanol, and dry it to obtain graphene-coated manganese oxide composite material.

[0056] Different composite materials were prepared using the above methods, and their formulations are shown in Table 2.

[0057] Table 2 Formula Table

[0058]

[0059] The size of the graphene is obtained by grinding with a grinder. The sheet diameter is D50. Zirconia beads with a particle size range of 0.5 to 1.5 μm are used as grinding material. The sheet diameter is controlled by controlling the grinding time. The D50 sheet diameter is continuously sampled and analyzed to obtain graphene that meets the expectations.

[0060] Part Three: Preparation of Environmentally Friendly Copper-Free Marine Antifouling Coating

[0061] Example 1

[0062] (1) Place 10g of xylene, 10g of propylene glycol methyl ether acetate and 10g of graphene-coated manganese oxide (M-1) in a stirrer and stir at room temperature and high speed to disperse them into a uniform liquid.

[0063] (2) Mix 5g of butyl acetate, 5g of methyl ethyl ketone, 2g of iron oxide red, 2g of talc, 1g of mica powder, 0.5g of BYK2150, 0.2g of AFCONA-2040, and 0.5g of AFCONA-4010 into a uniform slurry, then place it in a grinder for grinding. Remove it when the particle size is less than 20um.

[0064] (3) Add the liquid from step (1), the slurry from step (2), 50g of SPC-1 resin from Example 1, and 5g of polyamide wax into a mixer, stir and mix evenly, discharge, filter, and package the finished product TF-SPC1.

[0065] (4) Apply epoxy primer to the polished 3mm thick steel plate, allowing the dry film thickness to reach 80µm. Then apply intermediate coat to achieve a dry film thickness of 120µm. Finally, spray the finished TF-SPC1 coating onto the plate and allow it to air dry at room temperature for 7 days until fully cured, achieving a dry film thickness of 100µm. Test the coating properties according to national standards, as shown in Table 3.

[0066] Example 2

[0067] (1) Place 15g of xylene, 15g of propylene glycol methyl ether acetate and 15g of graphene-coated manganese oxide (M-2) in a stirrer and stir at room temperature and high speed to disperse them into a uniform liquid.

[0068] (2) Mix 5g of butyl acetate, 5g of methyl ethyl ketone, 2g of iron oxide red, 2g of talc, 1g of mica powder, 0.5g of BYK108, 0.2g of BYK-066N, and 0.5g of AFCONA-4077 into a uniform slurry, then place it in a grinder for grinding. Remove the slurry when the particle size is less than 20um.

[0069] (3) Add the liquid from step (1), the slurry from step (2), 39g of SPC-2 resin from Example 2, and 1g of bentonite into a mixer, stir and mix evenly, discharge, filter, and package the finished product TF-SPC2.

[0070] (4) Apply epoxy primer to the polished 3mm thick steel plate, allowing the dry film thickness to reach 80µm. Then apply intermediate coat to achieve a dry film thickness of 120µm. Finally, spray the finished TF-SPC1 coating onto the plate and allow it to air dry at room temperature for 7 days until fully cured, achieving a dry film thickness of 100µm. Test the coating properties according to national standards, as shown in Table 3.

[0071] Example 3

[0072] (1) Place 12g of xylene, 12g of propylene glycol methyl ether acetate and 20g of graphene-coated manganese oxide (M-3) in a stirrer and stir at room temperature and high speed to disperse them into a uniform liquid.

[0073] (2) Mix 5g of butyl acetate, 5g of methyl ethyl ketone, 2g of iron oxide red, 2g of talc, 1g of mica powder, 1.0g of AFCONA4400, 0.3g of BYK-066N, and 0.5g of AFCONA-4077 into a uniform slurry, then place it in a grinder for grinding. Remove it when the particle size is less than 20um.

[0074] (3) Add the liquid from step (1), the slurry from step (2), 39g of SPC-3 resin from Example 3, and 1g of bentonite into a mixer, stir and mix evenly, discharge, filter, and package the finished product TF-SPC3.

[0075] (4) Apply epoxy primer to the polished 3mm thick steel plate, allowing the dry film thickness to reach 80µm. Then apply intermediate coat to achieve a dry film thickness of 120µm. Finally, spray the finished TF-SPC1 coating onto the plate and allow it to air dry at room temperature for 7 days until fully cured, achieving a dry film thickness of 100µm. Test the coating properties according to national standards, as shown in Table 3.

[0076] Example 4

[0077] (1) Place 12g of xylene, 12g of propylene glycol methyl ether acetate and 30g of graphene-coated manganese oxide (M-2) in a stirrer and stir at room temperature and high speed to disperse them into a uniform liquid.

[0078] (2) Mix 4g of butyl acetate, 3g of methyl ethyl ketone, 3g of iron oxide red, 2g of talc, 1.0g of AFCONA4400, 0.3g of BYK-066N, and 0.5g of AFCONA-4077 into a uniform slurry, then place it in a grinder for grinding. Remove it when the particle size is less than 20um.

[0079] (3) Add the liquid from step (1), the slurry from step (2), 32g of SPC-4 resin from Example 4, and 1g of attapulgite into a mixer, stir and mix evenly, discharge, filter, and package the finished product TF-SPC4.

[0080] (4) Apply epoxy primer to the polished 3mm thick steel plate, allowing the dry film thickness to reach 80µm. Then apply intermediate coat to achieve a dry film thickness of 120µm. Finally, spray the finished TF-SPC1 coating onto the plate and allow it to air dry at room temperature for 7 days until fully cured, achieving a dry film thickness of 100µm. Test the coating properties according to national standards, as shown in Table 3.

[0081] Comparative Example 1

[0082] It is largely the same as Example 2, except that the resin is an equal amount of SPC-A.

[0083] Comparative Example 2

[0084] It is largely the same as Example 2, except that the resin is an equal amount of SPC-B.

[0085] Comparative Example 3

[0086] It is largely the same as Example 2, except that the resin is an equal amount of SPC-C.

[0087] Part Four: Performance Testing

[0088] The adhesion, hardness, gloss, salt water resistance and anti-fouling ability of the samples were tested according to the test methods described in the above embodiments. The specific results are shown in Table 3.

[0089] Table 3 Statistical Table of Results

[0090]

[0091] Results analysis:

[0092] 1. As can be seen from Examples 1 to 4, the SPC-1 to SPC-4 resins of the present invention maintain consistently good performance in terms of adhesion, hardness, and gloss; the SPC-A to SPC-C resins all maintain good adhesion and gloss, while SPC-B and SPC-C are slightly softer in terms of hardness; acrylonitrile is a hard monomer, and SPC-C shows a slight decrease in hardness; vinyl glycidyl ether can introduce crosslinking sites into the polymer, so its absence will cause a slight decrease in the hardness of the paint film; the adhesion and gloss of the paint film are mainly determined by the ratio of acrylic acid and acrylate.

[0093] 2. As can be seen from Examples 1 to 4, the weather resistance and stain resistance are both strong, indicating that the anti-fouling ability of manganese oxide is effectively maintained. The stain resistance and weather resistance of Comparative Examples 1 to 3 show a weakening. Regarding weather resistance, fluorinated monomers, acrylonitrile, and unsaturated monomers with epoxy groups all affect weather resistance. Weather resistance is related to the properties of the resin itself and the compatibility of graphene-coated manganese oxide. Specifically, the epoxy groups that did not fully react during polymerization and the residual hydroxyl groups on the graphene surface undergo ring-opening reactions, improving the dispersion uniformity of graphene-coated manganese oxide and enhancing its properties. The coating exhibits the ability to maintain the integrity of the paint film in subsequent saltwater environments. In terms of antifouling ability, the coating of the present invention can effectively protect the stability of graphene-coated manganese oxide, preventing manganese oxide from being oxidized and reducing antifouling ability. Meanwhile, some literature also supports that fluorinated acrylate monomers can improve the antifouling ability of the coating. Comparative Example 3 shows a fogging layer on the coating surface, indicating that acrylonitrile reduces hardness and reduces the weather resistance of the paint film. Compared with Comparative Examples 1 and 2, the weather resistance phenomenon shows a difference, indicating that there may be no intrinsic relationship between the dispersion properties of acrylonitrile and graphene.

[0094] Based on the above data, it can be concluded that there is a close relationship between the performance of the resin and the anti-fouling ability of graphene-coated manganese oxide.

Claims

1. An environmentally friendly copper-free marine antifouling paint, characterized by, Comprise the following mass parts components: Modified acrylic resin 20~50 parts; Graphene coated manganese dioxide composite material 10~30 parts; Organic solvent and auxiliary agent; The modified acrylic resin is obtained by free radical solution polymerization reaction of monomers, the monomers include acrylic acid, acrylate monomer, fluorine-containing acrylate monomer, acrylonitrile, unsaturated monomer with epoxy group; The mass ratio of acrylic acid, acrylate monomer, fluorine-containing acrylate monomer, acrylonitrile, unsaturated monomer with epoxy group is 15~25: 50~100: 3~5: 6~9: 2~4; The acrylate monomer is one or more combinations of methyl acrylate, ethyl acrylate, methyl methacrylate and propyl acrylate; The fluorine-containing acrylate monomer is trifluoroethyl acrylate and / or hexafluorobutyl acrylate; The unsaturated monomer with epoxy group is one or more combinations of vinyl glycidyl ether, glycidyl acrylate and allyl glycidyl ether; The graphene coated manganese dioxide composite material is composed of manganese dioxide and graphene coated on the outer surface of manganese dioxide; The D50 particle size of the manganese dioxide is 10~40μm; The D50 sheet size of the graphene is 0.1-0.9μm; The weight ratio of manganese dioxide and graphene is 100: 10~20; The auxiliary agent is pigment filler, anti-settling agent, dispersant, defoaming agent; The amount of each auxiliary agent is: Pigment filler 5~20 parts Anti-settling agent 1~5 parts Dispersant 1~5 parts Defoaming agent 0.2~3 parts; The amount of organic solvent is 10~40 parts.

2. The environment-friendly copper-free marine antifouling coating according to claim 1, characterized in that, The pigment filler is two or several of iron oxide red, organic scarlet, talc powder, mica powder, barium sulfate, calcium carbonate, kaolin, and lithopone; The anti-settling agent is bentonite, attapulgite or polyamide wax; The dispersant is one or both of modified polyacrylate polymer and modified polyurethane polymer; The defoaming agent is one or both of organic silicon polymer, fluorocarbon modified organic silicon polymer, vinyl polymer and fluorocarbon modified vinyl polymer; The organic solvent is one or more of methyl ethyl ketone, butanone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, propylene glycol methyl ether acetate, isopropyl alcohol, n-butanol, toluene and xylene. 3.The environment-friendly copper-free marine antifouling coating according to claim 2, characterized in that, The dispersant is one or more of BYK2150, BYK-108, BYK-108, AFCONA-4010, AFCONA4077, AFCONA-4400, AFCONA4550 and AFCON-4570; The defoaming agent is one or more of BYK-066N, BYK-052N, BYK-8800, AFCONA-2022, AFCONA-2040 and AFCONA-2048. 4.The environment-friendly copper-free marine antifouling coating of claim 1, characterized in that, The preparation method of the modified acrylic resin is: adding acrylic acid, acrylic ester monomer, fluorine-containing acrylic ester monomer, acrylonitrile and unsaturated monomer with epoxy group into a solvent, heating to reflux temperature under inert gas atmosphere, adding part of initiator dropwise, reacting for 4-8 h, then adding the remaining initiator to eliminate monomer and keeping for 1-2 h; The weight ratio of the solvent and all monomers is 100-200:100; the solvent is one or more combinations of toluene, xylene, n-butanol, N,N-dimethylacetamide and butyl acetate; the initiator is azobisisobutyronitrile or benzoyl peroxide; the amount of the initiator is 1.5-4 wt% of the total amount of all monomers.

5. A method for preparing the environment-friendly copper-free marine antifouling paint according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: Step 1: dispersing the graphene-coated manganous oxide composite material into an organic solvent; Step 2: mixing the auxiliary agent, the modified acrylic resin and the dispersion liquid obtained in step 1 which are pre-dispersed in the organic solvent.

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