Piezoelectric superhydrophobic antifouling coating and preparation method and application thereof

Abstract

This invention discloses a piezoelectric superhydrophobic double-layer antifouling coating, its preparation method, and its application. By weight, the piezoelectric superhydrophobic double-layer antifouling coating comprises a piezoelectric underlayer coated on a substrate surface and a superhydrophobic surface layer coated on the piezoelectric underlayer. The piezoelectric underlayer is prepared from 114–130 parts of film-forming resin, 60–90 parts of inorganic piezoelectric material, 1–30 parts of inorganic conductive material, 1–25 parts of additives, and 42–53 parts of solvent. The superhydrophobic surface layer consists of a micro / nano structure layer and a hydrophobic layer coated on the micro / nano structure layer. The micro / nano structure layer is prepared from 22–39 parts of film-forming resin, 41–163 parts of nano-zinc oxide, 1–13 parts of additives, and 52–162 parts of solvent. The hydrophobic layer is prepared from 11–51 parts of low surface energy resin, 1–13 parts of additives, and 52–162 parts of solvent. The antifouling coating prepared by this invention does not contain any toxic substances and will not release toxins into the ocean during use, making it environmentally friendly. Furthermore, this invention utilizes ocean wave energy for antifouling, representing a novel energy-saving and emission-reducing antifouling strategy.

Description

Technical Field

[0001] This invention relates to the field of marine antifouling coating technology, specifically to a piezoelectric superhydrophobic antifouling coating, its preparation method, and its application. Background Technology

[0002] Ships, offshore platforms, and other facilities are essential components of maritime transport and marine exploration. When these facilities are in prolonged contact with seawater, large amounts of marine organisms often adhere to their surfaces, causing marine biofouling. This biofouling can severely impact equipment. Harmful deposits increase hull surface roughness and fuel consumption, accelerate the corrosion of underwater facilities, and shorten their service life. Pollutants attached to ship surfaces can also lead to the invasion of alien species, disrupting the ecological balance. Therefore, preventing marine pollution is of paramount importance for the exploration and utilization of marine resources.

[0003] Traditional marine antifouling coatings contain toxic agents. These coatings work by releasing these toxic agents at a certain rate to create a toxic environment that prevents marine organisms from attaching. Obviously, as the antifouling agent is continuously released, its antifouling effect gradually decreases. While traditional marine antifouling coatings play a role in preventing fouling, they also cause some harm to the marine environment and marine life.

[0004] In addition, some researchers have proposed green and safe superhydrophobic coatings, such as the Chinese invention patent application with application number 201710504936.1, which discloses "a method for preparing a nano zinc oxide epoxy resin composite superhydrophobic coating". The superhydrophobic coating is prepared by using materials such as nano zinc oxide and epoxy resin. It has excellent superhydrophobic properties. However, in the marine environment, offshore industrial facilities are immersed in seawater for a long time. Therefore, the requirements for antifouling coatings for offshore industrial facilities are more stringent. It is difficult to meet the antifouling requirements by using only superhydrophobic coatings to control the hydrophobicity of the substrate of offshore industrial facilities. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a piezoelectric superhydrophobic antifouling coating, its preparation method, and its application. This invention proposes a piezoelectric superhydrophobic antifouling coating, its preparation method, and its application. The resulting piezoelectric superhydrophobic antifouling coating not only reduces the attachment sites of organisms on the coating through its superhydrophobic surface, but also generates active oxygen through the reaction of charged piezoelectric layers with water, achieving bactericidal and antifouling properties.

[0006] To achieve the above objectives, the technical solution designed by the present invention is as follows:

[0007] This invention provides a piezoelectric superhydrophobic antifouling coating. By weight, the piezoelectric superhydrophobic antifouling coating comprises a piezoelectric underlayer coated on a substrate surface and a superhydrophobic surface layer coated on the piezoelectric underlayer. The piezoelectric underlayer is prepared from 114-130 parts of film-forming resin, 60-90 parts of inorganic piezoelectric material, 1-30 parts of inorganic conductive material, 25-33 parts of additives, and 42-53 parts of solvent. The superhydrophobic surface layer consists of a micro / nano structure layer and a hydrophobic layer coated on the micro / nano structure layer. The micro / nano structure layer is prepared from 22-39 parts of film-forming resin, 41-163 parts of nano-zinc oxide, 7-13 parts of additives, and 52-162 parts of solvent. The hydrophobic layer is prepared from 11-51 parts of low surface energy resin, 5-13 parts of additives, and 52-162 parts of solvent.

[0008] Compared to other technologies, this invention employs a layer-by-layer spraying coating technique. The bottom layer uses piezoelectric catalysis to kill bacteria and other microorganisms attached to the coating, while the top layer uses constructed micro-nano structures to reduce attachment sites for larger organisms. This invention plays a role in preventing fouling in two crucial processes of marine fouling formation, combining two antifouling strategies with a simple spraying process to extend the coating's lifespan.

[0009] Furthermore, the piezoelectric bottom layer is prepared from 114-120 parts of film-forming resin, 82-88 parts of inorganic piezoelectric material, 3-17.8 parts of inorganic conductive material, 26.8-28 parts of additives, and 45-53 parts of solvent; the micro / nano structure layer is prepared from 39 parts of film-forming resin, 148 parts of nano zinc oxide, 10-11 parts of additives, and 137-162 parts of solvent; and the hydrophobic layer is prepared from 41 parts of low surface energy resin, 5 parts of additives, and 162 parts of solvent.

[0010] This invention does not add toxic substances and will not release toxic materials into the ocean during use, thus having the advantage of being environmentally friendly.

[0011] Furthermore, the film-forming resin is at least one of epoxy resin, fluorocarbon resin, and polyurethane resin; the additive is at least one of dispersant, defoamer, anti-settling agent, and curing agent; and the solvent is at least one of xylene, trifluorotoluene, n-hexane, and toluene.

[0012] This invention uses a resin with anti-corrosion properties as the film-forming material, which is often used in marine facilities such as ships due to its physicochemical stability, mechanical properties and adhesion to the substrate.

[0013] Furthermore, in the piezoelectric bottom layer, the inorganic piezoelectric material is at least one of zinc oxide, barium titanate, and tourmaline; the inorganic conductive material is at least one of multi-walled carbon nanotubes, single-walled carbon nanotubes, silver powder, copper powder, and graphene.

[0014] This invention does not add toxic substances but instead adds inorganic piezoelectric materials. It utilizes the energy of ocean waves to create external mechanical vibration conditions, thereby achieving the purpose of sterilization and antifouling. By adding inorganic conductive materials, this invention provides more conduction paths in the coating system to collect and transfer the charge generated by the inorganic piezoelectric materials under external mechanical vibration to the surface of the coating. This reacts with the water around the coating to generate more active oxygen, thereby enhancing the antibacterial and antifouling properties of the coating.

[0015] Furthermore, in the piezoelectric bottom layer, the inorganic piezoelectric material is zinc oxide, and the zinc oxide is one of the following: flower-shaped zinc oxide, tetraneedle-shaped zinc oxide whiskers, and zinc oxide nanowires.

[0016] This invention uses zinc oxide with different morphologies as fillers, and the coating made by using four needle-shaped zinc oxide whiskers has strong piezoelectricity.

[0017] Furthermore, in the piezoelectric underlayer, the inorganic piezoelectric material is tetrapter-shaped zinc oxide whiskers.

[0018] Furthermore, the zinc oxide nanostructure layer is at least one of 150 nm spherical zinc oxide, 100 nm spherical zinc oxide, 50 nm spherical zinc oxide, and 10 nm spherical zinc oxide.

[0019] This invention uses nano-zinc oxide of different particle sizes to construct a micro-nano structure layer. The coating has a large water contact angle, and the constructed superhydrophobic surface can exert a better antifouling effect.

[0020] Furthermore, the low surface energy resin of the hydrophobic layer is at least one of organosilicon resin, fluorocarbon resin, and fluorosilicone resin.

[0021] This invention uses a low surface energy resin as the outermost layer of the coating, which further improves the superhydrophobic properties of the coating to reduce the attachment sites of large fouling organisms.

[0022] The present invention also provides a method for preparing the piezoelectric superhydrophobic antifouling coating, comprising the following steps:

[0023] (1) Preparation of piezoelectric undercoat: Weigh the film-forming resin, inorganic piezoelectric material, inorganic conductive material, additives and solvent by weight, and mix the components evenly to obtain the piezoelectric undercoat.

[0024] (2) Preparation of superhydrophobic surface coating: Weigh the film-forming resin, nano zinc oxide, additives and solvent by weight, and mix the components evenly to obtain a micro-nano structure layer coating; then weigh the low surface energy resin, additives and solvent by weight, and mix the components evenly to obtain a hydrophobic layer coating.

[0025] (3) Coating of the piezoelectric underlayer: Apply the piezoelectric underlayer coating to the surface of the substrate and dry it until it is surface dry to form the piezoelectric underlayer;

[0026] (4) Coating of superhydrophobic surface layer: The micro-nano structure layer coating is uniformly sprayed on the semi-dry piezoelectric substrate surface. After drying until completely dry, the hydrophobic layer coating is uniformly sprayed on the micro-nano structure layer. After drying, the micro-nano structure layer and the hydrophobic layer together form a superhydrophobic surface layer.

[0027] This invention combines a superhydrophobic surface layer with a piezoelectric bottom layer, utilizing the synergistic effect of the two antifouling strategies to achieve better antifouling effect and longer service life.

[0028] Further, in step 3), the drying conditions are 90°C for 25 min; in step 4), the first drying conditions are 60°C for 50 min; and the second drying conditions are 30°C for 30 min.

[0029] The present invention uses the same film-forming resin and prepares the composite coating using a semi-dry spraying process. By "seeding" the slurry containing zinc oxide, film-forming resin and other substances used to construct the micro-nano structure on a semi-dry piezoelectric substrate, the interface problem between coatings can be solved.

[0030] This invention provides an application of the piezoelectric superhydrophobic antifouling coating in the antifouling topcoat of ships, offshore platforms and offshore industrial facilities.

[0031] This invention not only has excellent antifouling properties, but is also environmentally friendly, has a simple preparation process, low cost, and is applicable to most marine facility substrates, thus having broad application prospects.

[0032] The principle of this invention:

[0033] (1) A layer-by-layer spraying coating technology is adopted. The bottom layer kills bacteria and other microorganisms attached to the coating based on piezoelectric catalysis, while the top layer reduces the attachment sites of large organisms on the coating based on the constructed micro-nano structure. It plays a role in preventing fouling in two important processes of marine fouling. This invention combines two antifouling strategies with a simple spraying process to extend the service life of the coating.

[0034] (2) Based on the two antifouling strategies of piezoelectric catalysis and construction of micro-nano structures, considering that nano zinc oxide is both a piezoelectric crystal material and has the potential to construct surface micro-nano structures, this study uses piezoelectric fillers and film-forming resin as the main components, adds conductive fillers to enhance the charge transport capability of the piezoelectric bottom layer so that the coating can achieve the purpose of killing microorganisms through wave response; then, zinc oxide is used to construct a superhydrophobic layer; finally, a low surface energy resin is used as the outermost layer of the coating to further improve the superhydrophobic performance of the coating in order to reduce the attachment sites of large fouling organisms.

[0035] (3) The nano zinc oxide on the surface smoothly transfers the charge generated by the piezoelectric bottom layer under the force of the waves to the coating surface, and plays the role of "charge transfer bridge"; at the same time, since zinc oxide itself has the ability of piezoelectric catalysis, the zinc oxide on the surface not only transfers the charge generated by the piezoelectric bottom layer, but also generates its own charge to the coating surface to react with the surrounding water and dissolved oxygen to generate superoxide radicals, hydroxyl radicals and other active oxygen, which enhances the piezoelectric catalytic bactericidal effect of the coating.

[0036] (4) Since the prepared coating is a structure, it is particularly important to solve the interface problem between the two coatings. Therefore, the same film-forming resin was selected for the structure in this study and the composite coating was prepared by a semi-dry spraying process. The slurry of zinc oxide, film-forming resin and other substances used to construct the micro-nano structure was "seeded" on the semi-dry piezoelectric substrate to solve the interface problem between the coatings.

[0037] (5) The superhydrophobic surface layer of the present invention is constructed by a micro / nano structure layer and a hydrophobic layer. Achieving a superhydrophobic surface requires high surface roughness and low surface tension. Constructing a micro / nano structure increases surface roughness, while the hydrophobic layer reduces surface tension, thereby increasing the water contact angle of the coating. Combining these two methods can effectively construct a superhydrophobic surface. The present invention adds nano-zinc oxide to the micro / nano structure layer and a low surface energy resin to the hydrophobic layer to achieve the superhydrophobic effect. Attached Figure Description

[0038] Figure 1 The piezoelectric output diagrams of samples 1-8 and the piezoelectric sublayer of sample 1 under 200 W ultrasonic power are shown.

[0039] Figure 2 Here is a summary diagram of the water contact angles of samples 1-8 and the piezoelectric substrate of sample 1;

[0040] Figure 3 A summary graph showing the content of hydroxyl radicals released under ultrasonic conditions over a period of time for the control group and coatings 1-8 of samples.

[0041] Figure 4 A summary graph showing the content of superoxide radicals released under ultrasonic conditions over a period of time for the control group and coatings 1-8 of samples.

[0042] Figure 5 The graph shows the antibacterial test results for the control group and coatings 1-8 of the samples.

[0043] Figure 6 The image shows the anti-algae test results for the control group and the coating of sample 1. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can understand it. Example 1

[0045] A method for preparing a piezoelectric superhydrophobic antifouling coating, comprising the following steps:

[0046] (1) Preparation of piezoelectric undercoat: 50 parts by weight of xylene were added to a disperser, and 1.2 parts of defoamer, 1.8 parts of anti-settling agent, and 1 part of dispersant were added at a linear velocity of 6 m / s and stirred for 10 min. 120 parts of epoxy resin were added at a linear velocity of 10 m / s and stirred for 60 min to form a slurry. 82 parts of tetraneedle-shaped zinc oxide whiskers and 3 parts of multi-walled carbon nanotubes were added and ultrasonically dispersed at a high power of 300W for 30 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 24 parts of curing agent were added and stirred for 5 min to obtain slurry a, i.e., the piezoelectric undercoat.

[0047] (2) Preparation of superhydrophobic surface coating: 146 parts by weight of xylene were added to a disperser, and 1 part of defoamer and 1.4 parts of anti-settling agent were added at a linear velocity of 6 m / s, and stirred for 10 min. 39 parts of epoxy resin were added at a linear velocity of 10 m / s, and stirred for 20 min to form a slurry. 74 parts of 100 nm spherical zinc oxide and 74 parts of 10 nm spherical zinc oxide were added, and ultrasonically dispersed at a high power of 300 W for 40 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 8 parts of curing agent were added and stirred for 5 min to obtain slurry b, i.e., the micro-nano structure layer coating.

[0048] 41 parts of silicone resin, 162 parts of n-hexane, and 5 parts of curing agent were added to a disperser and stirred at a linear velocity of 6 m / s for 15 min to obtain slurry c, which is the hydrophobic coating.

[0049] (3) Coating of the piezoelectric underlayer: Spray the piezoelectric underlayer coating evenly onto the tinplate sheet and dry it at 90°C for 25 minutes until it is semi-dry to form the piezoelectric underlayer.

[0050] (4) Coating of superhydrophobic surface layer: The micro-nano structure layer coating is uniformly sprayed on the semi-dry piezoelectric substrate surface, dried at 60℃ for 50 min, and then the hydrophobic layer coating is uniformly sprayed on the micro-nano structure layer. After drying at 30℃ for 30 min, the micro-nano structure layer and the hydrophobic layer together form a superhydrophobic surface layer.

[0051] Example 2

[0052] A method for preparing a piezoelectric superhydrophobic antifouling coating, comprising the following steps:

[0053] (1) Preparation of piezoelectric undercoat: 45 parts by weight of xylene were added to a disperser, and 1.5 parts of defoamer and 2.5 parts of anti-settling agent were added at a linear velocity of 6 m / s, and stirred for 5 min. 118 parts of epoxy resin were added at a linear velocity of 10 m / s, and stirred for 60 min to form a slurry. 88 parts of flower-shaped zinc oxide and 13.3 parts of copper powder were added and ultrasonically dispersed at a high power of 300 W for 30 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 23.6 parts of curing agent were added and stirred for 5 min to obtain slurry a, i.e., the piezoelectric undercoat.

[0054] (2) Preparation of superhydrophobic surface coating: 137 parts by weight of xylene were added to a disperser, and 1 part of defoamer and 1 part of anti-settling agent were added at a linear velocity of 6 m / s, and stirred for 10 min. 39 parts of epoxy resin were added at a linear velocity of 10 m / s, and stirred for 20 min to form a slurry. 100 parts of 100 nm spherical zinc oxide and 48 parts of 10 nm spherical zinc oxide were added, and ultrasonically dispersed at a high power of 300 W for 40 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 8 parts of curing agent were added and stirred for 5 min to obtain slurry b, i.e., the micro-nano structure layer coating.

[0055] 41 parts of silicone resin, 162 parts of n-hexane, and 5 parts of curing agent were added to a disperser and stirred at a linear velocity of 6 m / s for 15 min to obtain slurry c, which is the hydrophobic coating.

[0056] (3) Coating of the piezoelectric underlayer: Spray the piezoelectric underlayer coating evenly onto the tinplate sheet and dry it at 90°C for 25 minutes until it is semi-dry to form the piezoelectric underlayer.

[0057] (4) Coating of superhydrophobic surface layer: The micro-nano structure layer coating is uniformly sprayed on the semi-dry piezoelectric substrate surface, dried at 60℃ for 50 min, and then the hydrophobic layer coating is uniformly sprayed on the micro-nano structure layer. After drying at 30℃ for 30 min, the micro-nano structure layer and the hydrophobic layer together form a superhydrophobic surface layer. Example 3

[0058] A method for preparing a piezoelectric superhydrophobic antifouling coating, comprising the following steps:

[0059] (1) Preparation of piezoelectric undercoat: 53 parts by weight of xylene were added to a disperser, and 1.5 parts of defoamer and 2.5 parts of anti-settling agent were added at a linear velocity of 6 m / s, and stirred for 5 min. 114 parts of epoxy resin were added at a linear velocity of 10 m / s, and stirred for 60 min to form a slurry. 86 parts of zinc oxide nanowires and 17.8 parts of graphene were added and ultrasonically dispersed at a high power of 300W for 30 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 22.8 parts of curing agent were added and stirred for 5 min to obtain slurry a, i.e., the piezoelectric undercoat.

[0060] (2) Preparation of superhydrophobic surface coating: 162 parts by weight of xylene were added to a disperser, and 1 part of defoamer and 2 parts of anti-settling agent were added at a linear velocity of 6 m / s, and stirred for 10 min. 39 parts of epoxy resin were added at a linear velocity of 10 m / s, and stirred for 20 min to form a slurry. 74 parts of 100 nm spherical zinc oxide and 74 parts of 50 nm spherical zinc oxide were added, and ultrasonically dispersed at a high power of 300 W for 40 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 8 parts of curing agent were added and stirred for 5 min to obtain slurry b, i.e., the micro-nano structure layer coating.

[0061] 41 parts of silicone resin, 162 parts of n-hexane, and 5 parts of curing agent were added to a disperser and stirred at a linear velocity of 6 m / s for 15 min to obtain slurry c, which is the hydrophobic coating.

[0062] (3) Coating of the piezoelectric underlayer: Spray the piezoelectric underlayer coating evenly onto the tinplate sheet and dry it at 90°C for 25 minutes until it is semi-dry to form the piezoelectric underlayer.

[0063] (4) Coating of superhydrophobic surface layer: The micro-nano structure layer coating is uniformly sprayed on the semi-dry piezoelectric substrate surface, dried at 60℃ for 50 min, and then the hydrophobic layer coating is uniformly sprayed on the micro-nano structure layer. After drying at 30℃ for 30 min, the micro-nano structure layer and the hydrophobic layer together form a superhydrophobic surface layer. Example 4

[0064] A method for preparing a piezoelectric superhydrophobic antifouling coating, comprising the following steps:

[0065] (1) Preparation of piezoelectric undercoat: 42 parts by weight of trifluorotoluene were added to a disperser, and 1.2 parts of defoamer, 1.8 parts of anti-settling agent, and 2 parts of dispersant were added at a linear velocity of 6 m / s and stirred for 10 min. 114 parts of fluorocarbon resin were added at a linear velocity of 10 m / s and stirred for 60 min to form a slurry. 60 parts of barium titanate and 1 part of single-walled carbon nanotubes were added and ultrasonically dispersed at a high power of 300 W for 30 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 20 parts of curing agent were added and stirred for 5 min to obtain slurry a, i.e., the piezoelectric undercoat.

[0066] (2) Preparation of superhydrophobic surface coating: 52 parts by weight of trifluorotoluene were added to a disperser, and 1 part of defoamer and 2 parts of anti-settling agent were added at a linear velocity of 6 m / s, and stirred for 10 min. 22 parts of fluorocarbon resin were added at a linear velocity of 10 m / s, and stirred for 20 min to form a slurry. 41 parts of 50 nm spherical zinc oxide were added, and ultrasonically dispersed at a high power of 300 W for 40 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 4 parts of curing agent were added and stirred for 5 min to obtain slurry b, i.e., the micro-nano structure layer coating.

[0067] 15 parts of fluorocarbon resin, 52 parts of trifluorotoluene, and 5 parts of curing agent were added to a disperser and stirred at a linear velocity of 6 m / s for 15 min to obtain slurry c, which is the hydrophobic coating.

[0068] (3) Coating of the piezoelectric underlayer: Spray the piezoelectric underlayer coating evenly onto the tinplate sheet and dry it at 90°C for 25 minutes until it is semi-dry to form the piezoelectric underlayer.

[0069] (4) Coating of superhydrophobic surface layer: The micro-nano structure layer coating is uniformly sprayed on the semi-dry piezoelectric substrate surface, dried at 60℃ for 50 min, and then the hydrophobic layer coating is uniformly sprayed on the micro-nano structure layer. After drying at 30℃ for 30 min, the micro-nano structure layer and the hydrophobic layer together form a superhydrophobic surface layer. Example 5

[0070] A method for preparing a piezoelectric superhydrophobic antifouling coating, comprising the following steps:

[0071] (1) Preparation of piezoelectric undercoat: 53 parts by weight of xylene were added to a disperser, and 1.2 parts of defoamer, 1.8 parts of anti-settling agent, and 2 parts of dispersant were added at a linear velocity of 6 m / s and stirred for 10 min. 130 parts of polyurethane resin were added at a linear velocity of 10 m / s and stirred for 60 min to form a slurry. 90 parts of tourmaline and 30 parts of silver powder were added and ultrasonically dispersed at a high power of 300 W for 30 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 28 parts of curing agent were added and stirred for 5 min to obtain slurry a, i.e., the piezoelectric undercoat.

[0072] (2) Preparation of superhydrophobic surface coating: 162 parts by weight of xylene were added to a disperser, and 2.5 parts of defoamer and 1.5 parts of anti-settling agent were added at a linear velocity of 6 m / s, and stirred for 10 min. 39 parts of polyurethane resin were added at a linear velocity of 10 m / s, and stirred for 20 min to form a slurry. 163 parts of 50 nm spherical zinc oxide were added, and ultrasonically dispersed at a high power of 300 W for 40 min. After uniform dispersion, the mixture was added to a disperser, the speed was adjusted to 6 m / s, and 9 parts of curing agent were added and stirred for 5 min to obtain slurry b, i.e., the micro-nano structure layer coating.

[0073] 51 parts of fluorosilicone resin, 162 parts of toluene, and 13 parts of curing agent were added to a disperser and stirred at a linear velocity of 6 m / s for 15 min to obtain slurry c, which is the hydrophobic coating.

[0074] (3) Coating of the piezoelectric underlayer: Spray the piezoelectric underlayer coating evenly onto the tinplate sheet and dry it at 90°C for 25 minutes until it is semi-dry to form the piezoelectric underlayer.

[0075] (4) Coating of superhydrophobic surface layer: The micro-nano structure layer coating is uniformly sprayed on the semi-dry piezoelectric substrate surface, dried at 60℃ for 50 min, and then the hydrophobic layer coating is uniformly sprayed on the micro-nano structure layer. After drying at 30℃ for 30 min, the micro-nano structure layer and the hydrophobic layer together form a superhydrophobic surface layer.

[0076] Example 6

[0077] The preparation method of the piezoelectric superhydrophobic antifouling coating in this embodiment is the same as that in Embodiment 1, except that the inorganic piezoelectric material in this embodiment uses 82 parts of flake zinc oxide. Example 7

[0078] The preparation method of the piezoelectric superhydrophobic antifouling coating in this embodiment is the same as that in Embodiment 1, except that the inorganic piezoelectric material in this embodiment uses 60 parts of tetraneedle-shaped zinc oxide whiskers. Example 8

[0079] The preparation method of the piezoelectric superhydrophobic antifouling coating in this embodiment is the same as that in Embodiment 1, except that the inorganic conductive material in this embodiment is 30 parts of multi-walled carbon nanotubes. Comparative Example 1

[0080] A method for preparing a piezoelectric bactericidal coating, comprising the following steps:

[0081] (1) Preparation of piezoelectric coating: 50 parts by weight of xylene were added to a disperser, and 1.2 parts of defoamer, 1.8 parts of anti-settling agent, and 1 part of dispersant were added at a linear velocity of 6 m / s and stirred for 10 min. 120 parts of epoxy resin were added at a linear velocity of 10 m / s and stirred for 60 min to form a slurry. 82 parts of tetraneedle-shaped zinc oxide whiskers and 3 parts of multi-walled carbon nanotubes were added and ultrasonically dispersed at a high power of 300 W for 30 min. After uniform dispersion, the mixture was added to the disperser, the speed was adjusted to 6 m / s, and 24 parts of curing agent were added and stirred for 5 min to obtain the piezoelectric coating.

[0082] (2) Application of piezoelectric coating: The piezoelectric coating material is evenly sprayed onto the tinplate and dried at 90°C to form a piezoelectric bactericidal coating. Example 9

[0083] Performance testing of piezoelectric superhydrophobic antifouling coating

[0084] Antifouling coatings were prepared according to Examples 1-8 and Comparative Example 1, resulting in Sample 1, Sample 2, Sample 3, Sample 4, Sample 5, Sample 6, Sample 7, Sample 8 and the piezoelectric underlayer of Sample 1.

[0085] (1) Testing of piezoelectric properties: To test the open-circuit voltage of the coating, the sample encapsulated in PET is connected to an electrochemical workstation using wires. An ultrasonic force of 200 W is applied at a frequency of 0.5 Hz. The output voltage of the piezoelectric film is detected using a CHI 760E electrochemical workstation. The test results are shown in […]. Figure 1 .

[0086] Depend on Figure 1 It can be seen that samples 1, 2, 3, and the piezoelectric underlayer of sample 1 all exhibit piezoelectricity. The output voltage of the piezoelectric underlayer of sample 1 is already relatively high, and the output voltage of the composite coating is further increased after applying the superhydrophobic surface layer. Under the external mechanical vibration of simulated ocean waves, the asymmetric structure of the piezoelectric crystal causes the centers of positive and negative charges inside to shift, forming an electric dipole moment and a built-in electric field, causing electrons and holes to move in opposite directions to the material surface. A certain amount of conductive material helps to enhance the ability of the piezoelectric coating to release electrical signals. On the one hand, conductive materials can promote the uniform dispersion of piezoelectric materials to a certain extent; on the other hand, compounding an appropriate amount of conductive material into the polymer matrix can improve the electrical signal transmission capability of the polymer to obtain a better piezoelectric response effect.

[0087] In summary, samples 1-2 exhibited good piezoelectric properties, with the composite piezoelectric marine antifouling coating of sample 1 showing the best performance. Comparing samples 1 and 6 reveals significant differences in piezoelectricity resulting from the use of zinc oxide with different morphologies as fillers. Example 1, using tetragonal zinc oxide whiskers as the inorganic piezoelectric filler, produced an antifouling coating with better piezoelectricity. Comparing samples 1 and 7 shows that high and low concentrations of tetragonal zinc oxide whiskers, respectively, were used as inorganic piezoelectric materials. This demonstrates that a high concentration of piezoelectric filler (82 parts by weight of tetragonal zinc oxide whiskers) significantly enhances the piezoelectric properties of the coating, as more piezoelectric filler facilitates the formation of charge transport pathways in the resin. Samples 1 and 8, using low and high concentrations of multi-walled carbon nanotubes, respectively, as inorganic conductive materials, indicate that a high concentration of conductive filler (30 parts by weight of multi-walled carbon nanotubes) weakens the piezoelectric properties of the coating. This is because excessive carbon nanotubes encapsulate zinc oxide, causing it to lose its semiconductor properties.

[0088] (2) Water contact angle test: A superhydrophobic surface is a surface with a static water contact angle (WCA) greater than 150°. Superhydrophobic surfaces can form an air layer in the space of microstructures / nanostructures, thereby significantly reducing the contact between seawater and the substrate surface, thus reducing the attachment sites of organisms and achieving the purpose of antifouling.

[0089] The specific steps are as follows: Samples 1-8 and the piezoelectric sublayer of sample 1 were tested using a JC2000C3 contact angle measuring instrument. The samples were placed on the instrument platform, deionized water was used, and measurements were performed using the angle measurement method with a precision of 0.5. The test results are shown below. Figure 2 .

[0090] Depend on Figure 2 It can be seen that among all samples, sample 1 has the largest water contact angle of 152.12°, indicating that the water contact angle of the superhydrophobic surface is closely related to the particle size of zinc oxide. The smaller the particle size, the larger the water contact angle of the surface layer, and the better the hydrophobic effect. The superhydrophobic coating constructed by sample 1 can achieve better antifouling effect. Example 10

[0091] Antifouling coatings were prepared according to Examples 1-8, and Samples 1, 2, 3, 4, 5, 6, 7 and 8 were obtained respectively. A blank coating was set up as a control group. The thickness of the coating was 300 μm.

[0092] (1) Test of hydroxyl radical production: Hydroxyl radical (·OH) is generally considered to be an active group that plays a bactericidal role. The 2-hydroxyterephthalic acid generated by its reaction with terephthalic acid has a significant fluorescence effect and has a fluorescence characteristic intensity peak at a wavelength of about 425 nm. Applying fluorescence technology to the detection of intermediate free radicals in the degradation process can prove that hydroxyl radicals with strong oxidizing properties are generated during the catalytic degradation process.

[0093] The specific steps are as follows:

[0094] (i) Add 50 mL of 5×10⁸ mol of the blank control group and samples 1-8 respectively. -4 mol·L -1 In an aqueous solution of terephthalic acid, a piezoelectric effect is provided by an ultrasonic cleaner with a power of 200 W.

[0095] (ii) Hydroxyl radical detection experiment was conducted under ultrasonic-simulated external mechanical vibration. 3 mL of liquid was aspirated every 5 min and then centrifuged at 9000 r·min. -1 After centrifugation at a certain speed for 5 minutes, the supernatant was collected.

[0096] (iii) The supernatant was analyzed and measured using an F-7000 fluorescence spectrophotometer to determine the concentration of 2-hydroxyterephthalic acid produced, and the amount of hydroxyl radicals produced in the sample during this period was calculated.

[0097] (2) Test of superoxide radical production: superoxide radicals (·O2) - O2 can react with nitroblue tetrazolium solution, causing a decrease in the UV absorption peak of nitroblue tetrazolium solution at 259 nm. Therefore, the UV-Vis absorption intensity of nitroblue tetrazolium solution during the experiment can be used to detect O2. - The existence and concentration of .

[0098] The specific steps are as follows:

[0099] (i) Add 50 mL of 2.5 × 10⁸ mol / L to the blank control group and samples 1-8 respectively. -5 mol·L -1 In a nitroblue tetrazolium solution, an ultrasonic cleaner with a power of 200 W provides piezoelectric effect.

[0100] (ii) Superoxide radical detection experiment was conducted under ultrasonic-simulated external mechanical vibration. 3 mL of liquid was aspirated every 5 min and then centrifuged at 9000 r·min. -1 After centrifugation at a certain speed for 5 minutes, the supernatant was collected.

[0101] (iii) The concentration of the nitroblue tetrazolium solution was determined by analyzing the supernatant using a UV-2600 ultraviolet-visible spectrophotometer, and the amount of hydroxyl radicals generated in the sample during this period was calculated.

[0102] Depend on Figures 3-4 It can be seen that, under the same time and conditions, Sample 1 produces higher levels of hydroxyl radicals and superoxide radicals than other samples, and this trend is consistent with the trend observed in the piezoelectric performance test. The coating can utilize the wave energy in the ocean to create external mechanical vibrations, causing electrons and holes to move in opposite directions to the material surface, reacting with dissolved oxygen and surrounding water to generate superoxide radicals, hydroxyl radicals, and other reactive oxygen species capable of killing bacteria and other microorganisms. This indicates that the environmentally friendly composite marine antifouling coating based on piezoelectric catalysis prepared in this invention can generate more reactive oxygen species that can kill bacteria.

[0103] (3) Antibacterial and antifouling performance test: Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were used as the dominant microorganisms for the antibacterial experiment. The blank control group sample and samples 1-8 were cut into the same size and sterilized for 30 min. 1.5 mL of bacterial suspension (1.0×10⁻⁶) was added. 5 CFU / mL of the bacterial culture solution was inoculated into EP tubes containing the sample. Pure tinplate was placed in the EP tubes as a control group for bacterial proliferation. The tubes were then cultured for 4 hours without sonication, followed by 8 hours of sonication at 50 kHz and 200 W. After co-cultivation, the bacterial solution was diluted to a certain factor, and an appropriate amount was spread onto solid culture medium and incubated at 37℃ for 12 hours. At the end of the experiment, the viable number of airborne bacteria in the culture medium was determined using the plate count method. Sterilization rate (%) = (original bacterial count - viable bacterial count) / original bacterial count × 100%.

[0104] Depend on Figure 5 Table 2 shows that the piezoelectric superhydrophobic antifouling coating prepared in this invention achieves a bactericidal rate of over 90% against Escherichia coli (Gram-negative bacteria) and over 91.5% against Staphylococcus aureus (Gram-positive bacteria). Sample 1 shows an antibacterial rate of 100% against both Escherichia coli and Staphylococcus aureus. This indicates that the coating has strong bactericidal and antifouling properties against both Gram-negative and Gram-positive bacteria.

[0105] Table 2 Summary of antibacterial rates of the control group and coatings 1-8 of the samples

[0106]

[0107] (4) Anti-algae and antifouling performance test: Anti-algae experiments were conducted using *Phaeodactylum tricornutum* and *Nyctaginea microphylla* as the dominant marine algae. Samples 1-8 were cut to the same size as glass slides and sterilized for 30 min along with the blank control group samples. 30 μL of algal solution of a certain concentration, 30 mL of artificial seawater, and the samples were placed in a petri dish and cultured under ultrasonic conditions at 50 kHz and 200 W for 3 h, then placed in a 20℃ incubator for 7 days. After co-cultivation, 200 μL of algal solution was taken and the absorbance was measured using an ELISA reader. Anti-algae rate (%) = (Absorbance of control group algal solution - Absorbance of sample algal solution) / Absorbance of control group algal solution × 100%.

[0108] Depend on Figure 6 As shown in Table 3, the anti-algae rate of sample 1 of the present invention reached 98.6% against *Phaeodactylum tricornutum* and 95.7% against *Nyctaginus simonii*, indicating that the coating has strong anti-algae and anti-fouling properties against both *Phaeodactylum tricornutum* and *Nyctaginus simonii*.

[0109] Table 3 Summary of algae resistance rates of the control group and coatings 1-8 (samples)

[0110]

[0111] All other parts not described in detail are existing technologies. Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A piezoelectric superhydrophobic antifouling coating, characterized in that: By weight, the piezoelectric superhydrophobic antifouling coating comprises a piezoelectric underlayer coated on the surface of a substrate and a superhydrophobic surface layer coated on the piezoelectric underlayer. The piezoelectric substrate is prepared from 114-120 parts of film-forming resin, 82-88 parts of inorganic piezoelectric material, 3-17.8 parts of inorganic conductive material, 26.8-28 parts of additives, and 45-53 parts of solvent; the superhydrophobic surface layer consists of a micro / nano structure layer and a hydrophobic layer coated on the micro / nano structure layer; the micro / nano structure layer is prepared from 39 parts of film-forming resin, 148 parts of nano zinc oxide, 10-11 parts of additives, and 137-162 parts of solvent; the hydrophobic layer is prepared from 41 parts of low surface energy resin, 5 parts of additives, and 162 parts of solvent. In the piezoelectric bottom layer, the inorganic piezoelectric material is zinc oxide, and the zinc oxide is one of flower-shaped zinc oxide, tetraneedle-shaped zinc oxide whiskers, and zinc oxide nanowires; the inorganic conductive material is at least one of multi-walled carbon nanotubes, copper powder, and graphene. The zinc oxide nanostructure layer is at least one of 150 nm spherical zinc oxide, 100 nm spherical zinc oxide, 50 nm spherical zinc oxide, and 10 nm spherical zinc oxide.

2. The piezoelectric superhydrophobic antifouling coating according to claim 1, characterized in that: The film-forming resin is at least one of epoxy resin, fluorocarbon resin and polyurethane resin; the additive is at least one of dispersant, defoamer, anti-settling agent and curing agent; the solvent is at least one of xylene, trifluorotoluene, n-hexane and toluene.

3. The piezoelectric superhydrophobic antifouling coating according to claim 1, characterized in that: The low surface energy resin of the hydrophobic layer is at least one of organosilicon resin, fluorocarbon resin, and fluorosilicone resin.

4. A method for preparing a piezoelectric superhydrophobic antifouling coating as described in any one of claims 1 to 3, characterized in that: Includes the following steps: (1) Preparation of piezoelectric undercoat: Weigh the film-forming resin, inorganic piezoelectric material, inorganic conductive material, additives and solvent by weight, and mix the components evenly to obtain the piezoelectric undercoat. (2) Preparation of superhydrophobic surface coating: Weigh the film-forming resin, nano zinc oxide, additives and solvent by weight, and mix the components evenly to obtain a micro-nano structure layer coating; then weigh the low surface energy resin, additives and solvent by weight, and mix the components evenly to obtain a hydrophobic layer coating. (3) Coating of the piezoelectric underlayer: Apply the piezoelectric underlayer coating to the surface of the substrate and dry it until it is surface dry to form the piezoelectric underlayer; (4) Coating of superhydrophobic surface layer: The micro-nano structure layer coating is uniformly sprayed on the semi-dry piezoelectric substrate surface. After drying until completely dry, the hydrophobic layer coating is uniformly sprayed on the micro-nano structure layer. After drying, the micro-nano structure layer and the hydrophobic layer together form a superhydrophobic surface layer.

5. The method for preparing the piezoelectric superhydrophobic antifouling coating according to claim 4, wherein in step 3), the drying conditions are 90°C for 25 min; and in step 4), the first drying conditions are 60°C for 50 min; and the second drying conditions are 30°C for 30 min.

6. The application of the piezoelectric superhydrophobic antifouling coating as described in any one of claims 1 to 3 in the antifouling of the bottom topcoat of ships and offshore industrial facilities.

Images