Preparation method and application of food-grade rice bran wax-based super-hydrophobic antibacterial coating
By using food-grade rice bran wax-based superhydrophobic and antibacterial coatings, the problems of mutual incompatibility between hydrophobic and antibacterial functions and insufficient safety in traditional coatings have been solved, enabling their widespread application in food and medical materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGKAI UNIV OF AGRI & ENG
- Filing Date
- 2026-05-27
- Publication Date
- 2026-06-23
Smart Images
Figure CN122255877A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of coating technology, and particularly relates to a method for preparing a food-grade rice bran wax-based superhydrophobic antibacterial coating and its application. Background Technology
[0002] Superhydrophobic coatings, with their unique surface wetting properties, have broad application prospects in antifouling, anticorrosion, and self-cleaning fields. Traditional preparation methods often rely on the synergistic construction of micro / nano rough structures and low surface free energy materials. In existing technologies, the low surface free energy component is mostly composed of fluorosilane compounds. These substances not only exhibit significant environmental toxicity and are difficult to degrade in the natural environment, easily causing long-term ecological pollution, but their potential hazards during production and use also limit their application in areas with high safety requirements, such as food contact and medical materials. This has become a core bottleneck restricting the large-scale promotion of superhydrophobic coatings. Composite coatings combining superhydrophobic and antibacterial functions are in increasingly urgent demand because they can simultaneously solve the two major problems of surface contamination adhesion and microbial growth. However, there is an irreconcilable interfacial compatibility conflict between the functional components of traditional antibacterial coatings (such as metal ions like silver and copper or organic antibacterial agents) and superhydrophobic components: hydrophilic antibacterial agents can disrupt the low-energy environment of the coating surface, leading to a significant decrease in hydrophobicity; while hydrophobic antibacterial agents are prone to reduced antibacterial activity due to differences in surface free energy, making it impossible to achieve long-term synergy between the two functions. Even with attempts to optimize the component ratio in some solutions, it is still difficult to balance the stability of superhydrophobic properties with the durability of antibacterial effects, resulting in a technical dilemma of "functional incompatibility". Existing superhydrophobic and antibacterial composite coatings generally suffer from insufficient raw material safety. Most components lack food-grade certification, exhibit poor biocompatibility, and fail to meet safety standards in fields such as food packaging, tableware, and medical consumables. While natural and renewable materials offer environmental advantages, coatings constructed solely from natural waxes and other materials often suffer from insufficient micro-nano structural stability and limited functionality, making it difficult to simultaneously achieve both superhydrophobic and antibacterial properties. In summary, developing a composite coating that uses food-grade natural materials as a matrix, is free of toxic components such as fluorine, achieves efficient synergy between superhydrophobicity and antibacterial function, and also has good biocompatibility and environmental friendliness has become a key technological need that urgently needs to be addressed in the current coating technology field. This is of great significance for expanding the application scenarios of superhydrophobic and antibacterial materials and promoting the development of environmentally friendly functional coatings. Summary of the Invention
[0003] To overcome the technical shortcomings of existing superhydrophobic antibacterial coatings, such as the environmental toxicity of fluorine-containing components, the mutual incompatibility between hydrophobic and antibacterial functions, insufficient raw material safety, and complex production processes, this invention proposes a method for preparing food-grade rice bran wax-based superhydrophobic antibacterial coatings and its application. This method is green and safe, has synergistic functions, is low in cost, and is easy to scale up for production.
[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a food-grade rice bran wax-based superhydrophobic and antibacterial coating includes the following steps: (1) Dissolve food-grade rice bran wax in a solvent and heat it to completely melt the rice bran wax to obtain a rice bran wax solution; add food-grade emulsifier to the rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed; (2) Disperse the nano antibacterial raw material in a non-polar solvent and sonicate it to form a uniform mixed solution; add silane coupling agent to the mixed solution, adjust the pH of the system to 3-5, and stir the reaction at 50-80℃ for 2-6 hours; after the reaction is completed, separate by centrifugation, wash with anhydrous ethanol to remove unreacted silane coupling agent, and vacuum dry to obtain hydrophobic nano antibacterial powder. (3) The rice bran wax-emulsifier composite solution obtained in step (1) is heated and stirred at 60-80℃ for 1-2 hours, and then the hydrophobic nano antibacterial powder obtained in step (2) is added and stirred until it is evenly dispersed to obtain the food-grade rice bran wax-based superhydrophobic antibacterial coating.
[0005] Rice bran wax is a natural, safe, and biodegradable food-grade material. This invention uses food-grade rice bran wax as the base material and food-grade emulsifier as the dispersant. It introduces nano-antibacterial raw materials modified with silane coupling agents and achieves a synergistic unity of environmental protection, superhydrophobicity, and antibacterial properties through a simple composite dispersion process. Moreover, the preparation process does not require complex equipment, the cost is controllable, and it is suitable for large-scale production.
[0006] Further, in step (1), the ratio of the amount of food-grade rice bran wax to the solvent is (1-10) g: 200 mL; The mass ratio of the food-grade rice bran wax to the food-grade emulsifier is (1-10):(0.1-1).
[0007] Further, in step (1), the solvent is selected from at least one of ethanol, isopropanol, methyl acetate, ethyl acetate and propyl acetate; The food-grade emulsifier includes hydrophilic emulsifiers containing polar functional groups (hydroxyl, carboxyl, amino groups) and hydrophobic emulsifiers containing non-polar functional groups (long-chain alkyl, aromatic groups); specifically selected from at least one of lecithin, stearic acid, sodium dodecyl sulfate, glyceryl monostearate, n-octyltriethoxysilane, polydimethylsiloxane, and sodium dodecylbenzenesulfonate.
[0008] Further, in step (2), the ratio of the amount of the nano antibacterial raw material, the non-polar solvent and the silane coupling agent is (5-10) g: 50 mL: (10-50) mL.
[0009] Furthermore, in step (2), the particle size of the hydrophobic nano-antibacterial powder is 50-100 nm.
[0010] Furthermore, in step (2), the nano antibacterial raw material is at least one of nano zinc oxide, nano silver oxide, and nano magnesium oxide; The nonpolar solvent is selected from at least one of diethyl ether, n-hexane, cyclohexane, and n-heptane; The silane coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane (KH-540), 3-aminopropyltriethoxysilane (KH-550), 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KA-560), 3-methacryloyloxypropyltrimethoxysilane (KH-570), and 3-mercaptopropyltrimethoxysilane (KH-590).
[0011] Further, in step (2), the pH is adjusted to pH=3-5.
[0012] Furthermore, the ratio of the rice bran wax-emulsifier composite solution to the hydrophobic nano-antibacterial powder is 200 mL: (1-10) g.
[0013] The present invention also provides a food-grade rice bran wax-based superhydrophobic antibacterial coating, which is prepared using the above-described preparation method.
[0014] This invention uses a rice bran wax-emulsifier composite system as the continuous phase and a hydrophobic nano-antibacterial raw material as the dispersed phase to form a uniformly dispersed and highly stable composite solution. The entire system is free of toxic components such as fluorosilanes and meets food-grade safety standards. This coating features uniform dispersion, good stability, and is non-toxic and environmentally friendly, and can be directly used to prepare functional coatings for substrate surfaces.
[0015] This invention also provides an application of a food-grade rice bran wax-based superhydrophobic and antibacterial coating in the preparation of a superhydrophobic coating on a glass substrate. The specific application process involves immersing the substrate to be treated in the aforementioned food-grade rice bran wax-based superhydrophobic and antibacterial coating solution. After immersion, the substrate is dried and cured to form a dense food-grade rice bran wax-based superhydrophobic and antibacterial coating on the substrate surface. The resulting coating exhibits a static water contact angle greater than 150° and a minimum surface free energy of 0.69 J / m². 2 It combines excellent superhydrophobicity, low adhesion, environmental friendliness, and broad-spectrum antibacterial properties.
[0016] The coating prepared by this invention can form a composite coating on the surface of a substrate with superhydrophobicity, low adhesion, environmental friendliness and antibacterial properties through a simple impregnation-drying curing process.
[0017] Compared with the prior art, the present invention has the following advantages and technical effects: (1) This invention effectively solves the technical contradiction in traditional technology that it is difficult to coordinate and maintain the superhydrophobic function and antibacterial function for a long time. Rice bran wax, as a renewable natural wax derived from rice bran, has a micro-nano rough structure formed after processing, which provides a physical basis for superhydrophobic performance. It forms a synergistic effect with the nano antibacterial raw material modified by silane coupling agent. This synergistic effect can increase the exposed surface area of the nano antibacterial raw material and enhance the antibacterial effect. It achieves a high degree of synergy between physical hydrophobic barrier and contact bactericidal function, so that the coating has both excellent superhydrophobic performance and long-lasting and efficient broad-spectrum antibacterial performance, breaking through the technical bottleneck of mutual restriction between hydrophobic and antibacterial functions in traditional coatings.
[0018] (2) By optimizing the interfacial coupling and synergistic enhancement mechanism between the matrix material and the nano-functional components, the mechanical stability and environmental adaptability of the coating were significantly improved. The prepared superhydrophobic antibacterial coating has a static water contact angle greater than 150° and a surface free energy as low as 0.69 J / m. 2 It has excellent superhydrophobic properties; at the same time, the coating has low adhesion, which can effectively reduce the adhesion of pollutants and maintain surface cleanliness in practical applications.
[0019] (3) The main components of the coating, rice bran wax and nano antibacterial raw materials, have good biocompatibility. Compared with the fluorinated compounds commonly used in traditional hydrophobic and oleophobic coatings, it is not only cheaper, but also significantly safer and more environmentally friendly, effectively broadening the application prospects of the coating material in food and drug packaging, medical materials and other fields. Attached Figure Description
[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The contact angles of the antibacterial coatings prepared in Examples 1-5 and Comparative Examples 1-2 are shown. Figure 2 The antibacterial images are of the antibacterial coatings prepared in Examples 1-5 and Comparative Examples 1-2. Figure 3 This is a scanning electron microscope image of the antibacterial coating prepared in Example 4. Detailed Implementation
[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0026] This invention provides a method for preparing a food-grade rice bran wax-based superhydrophobic antibacterial coating, comprising the following steps: (1) Preparation of rice bran wax-emulsifier composite solution: Dissolve food-grade rice bran wax in a solvent and heat until the rice bran wax is completely melted to obtain rice bran wax solution; add food-grade emulsifier to rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed; (2) Preparation of hydrophobic nano antibacterial powder: The nano antibacterial raw material is dispersed in a non-polar solvent and ultrasonically treated to form a uniform mixed solution; a silane coupling agent is added to the mixed solution, and the pH of the system is adjusted to 3-5 (e.g., pH=3, 4 or 5). The mixture is stirred at 50-80℃ (e.g., 50℃, 60℃, 70℃ or 80℃) for 2-6 h (e.g., 2h, 4h, 5h or 6h); after the reaction is completed, the mixture is centrifuged, washed with anhydrous ethanol to remove unreacted silane coupling agent, and vacuum dried to obtain hydrophobic nano antibacterial powder; (3) Heat and stir the rice bran wax-emulsifier composite solution obtained in step (1) at 60-80℃ (e.g., 60℃, 70℃ or 80℃) for 1-2 hours (e.g., 1 hour or 2 hours), then add the hydrophobic nano antibacterial powder obtained in step (2), and continue stirring until it is evenly dispersed to obtain food-grade rice bran wax-based superhydrophobic antibacterial coating.
[0027] In some optional embodiments of the present invention, in step (1), the ratio of food-grade rice bran wax to solvent is (1-10) g: 200 mL. Exemplarily, in the following preferred embodiments of the present invention, the ratio of food-grade rice bran wax to solvent is 4 g: 200 mL, 6 g: 200 mL, 8 g: 200 mL, or 10 g: 200 mL.
[0028] In some optional embodiments of the present invention, in step (1), the mass ratio of food-grade rice bran wax to food-grade emulsifier is (1-10):(0.1-1). Exemplarily, in the following preferred embodiments of the present invention, the mass ratio of food-grade rice bran wax to food-grade emulsifier is 4:0.2, 6:0.6, 8:0.8, or 10:1.
[0029] In some optional embodiments of the present invention, in step (1), the solvent is selected from at least one of ethanol, isopropanol, methyl acetate, ethyl acetate, and propyl acetate. Exemplarily, in the following preferred embodiments of the present invention, the solvent is ethanol, isopropanol, methyl acetate, ethyl acetate, or propyl acetate.
[0030] In some optional embodiments of the present invention, in step (1), the food-grade emulsifier is selected from at least one of lecithin, stearic acid, sodium lauryl sulfate, glyceryl monostearate, n-octyltriethoxysilane, polydimethylsiloxane, and sodium dodecylbenzenesulfonate. Exemplarily, in the following preferred embodiments of the present invention, the food-grade emulsifier is a mixture of lecithin, stearic acid, and sodium lauryl sulfate (in a 1:1 mass ratio), a mixture of n-octyltriethoxysilane and polydimethylsiloxane (in a 1:1 mass ratio), a mixture of glyceryl monostearate and sodium dodecylbenzenesulfonate (in a 1:1 mass ratio), or polydimethylsiloxane.
[0031] In some optional embodiments of the present invention, in step (2), the ratio of the amount of nano-antibacterial raw material, non-polar solvent, and silane coupling agent is (5-10) g: 50 mL: (10-50) mL. Exemplarily, in the following preferred embodiments of the present invention, the ratio of the amount of nano-antibacterial raw material, non-polar solvent, and silane coupling agent is 5 g: 50 mL: 10 mL, 10 g: 50 mL: 20 mL, 8 g: 50 mL: 30 mL, 10 g: 50 mL: 40 mL, or 9 g: 50 mL: 50 mL.
[0032] In some optional embodiments of the present invention, in step (2), the particle size of the hydrophobic nano-antibacterial powder is 50-100 nm. Exemplarily, in the following preferred embodiments of the present invention, the particle size of the hydrophobic nano-antibacterial powder is 50 nm, 60 nm, 80 nm, 90 nm or 100 nm.
[0033] In some optional embodiments of the present invention, in step (2), the nano antibacterial material is at least one of nano zinc oxide, nano silver oxide and nano magnesium oxide; for example, in the following preferred embodiments of the present invention, the nano antibacterial material is nano zinc oxide, nano silver oxide or nano magnesium oxide.
[0034] In some optional embodiments of the present invention, in step (2), the nonpolar solvent is selected from at least one of diethyl ether, n-hexane, cyclohexane and n-heptane; for example, in the following preferred embodiments of the present invention, the nonpolar solvent is diethyl ether, n-hexane, cyclohexane or n-heptane.
[0035] In some optional embodiments of the present invention, in step (2), the silane coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane (KH-540), 3-aminopropyltriethoxysilane (KH-550), 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KA-560), 3-methacryloyloxypropyltrimethoxysilane (KH-570), and 3-mercaptopropyltrimethoxysilane (KH-590). Exemplarily, in the following preferred embodiments of the present invention, the silane coupling agent is KH-540, KH-550, KA-560, KH-570, or KH-590.
[0036] In some optional embodiments of the present invention, the ratio of rice bran wax-emulsifier composite solution to hydrophobic nano-antibacterial powder is 200 mL: (1-10) g. Exemplarily, in the following preferred embodiments of the present invention, the ratio of rice bran wax-emulsifier composite solution to hydrophobic nano-antibacterial powder is 200 mL: 10 g, 200 mL: 1 g, 200 mL: 6 g, 200 mL: 8 g, or 200 mL: 4 g.
[0037] A food-grade rice bran wax-based superhydrophobic antibacterial coating can be prepared using the above preparation method.
[0038] The food-grade rice bran wax-based superhydrophobic and antibacterial coating prepared by this invention can be used to prepare superhydrophobic coatings on glass substrates. The specific application process is as follows: the substrate to be treated is immersed in a food-grade rice bran wax-based superhydrophobic and antibacterial coating solution. After immersion, it is dried and cured to form a dense food-grade rice bran wax-based superhydrophobic and antibacterial coating on the substrate surface.
[0039] All raw materials used in this invention were purchased from the market.
[0040] The technical solution of the present invention will be further illustrated by the following embodiments.
[0041] Example 1 A method for preparing a food-grade rice bran wax-based superhydrophobic and antibacterial coating includes the following steps: (1) Preparation of rice bran wax-emulsifier composite solution: Dissolve 4g of food-grade rice bran wax in 200mL of ethanol and heat until it is completely melted to obtain rice bran wax solution; add 0.1g of lecithin and 0.1g of stearic acid to the rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed; (2) Preparation of hydrophobic nano antibacterial powder: 5g of nano silver oxide was dispersed in 50mL of diethyl ether and ultrasonically treated to form a uniform mixed solution; 10mL of 3-aminopropyltrimethoxysilane (KH-540) was added to the mixed solution, the pH of the system was adjusted to 5, and the reaction was stirred at 80℃ for 6h; after the reaction was completed, the unreacted silane coupling agent was removed by centrifugation and washed with anhydrous ethanol, and the mixture was vacuum dried to obtain hydrophobic nano silver oxide powder with a diameter of 100nm. (3) Heat and stir 200 mL of the rice bran wax-emulsifier composite solution prepared in step (1) at 80°C for 2 hours, then add 10 g of the hydrophobic nano silver oxide powder prepared in step (2) and continue stirring until it is evenly dispersed to obtain a food-grade rice bran wax-based superhydrophobic antibacterial coating.
[0042] Example 2 A method for preparing a food-grade rice bran wax-based superhydrophobic and antibacterial coating includes the following steps: (1) Preparation of rice bran wax-emulsifier composite solution: Dissolve 6g of food-grade rice bran wax in 200mL of isopropanol and heat until it is completely melted to obtain rice bran wax solution; add 0.3g of stearic acid and 0.3g of sodium dodecyl sulfate to the rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed; (2) Preparation of hydrophobic nano antibacterial powder: 10g of nano magnesium oxide was dispersed in 50mL of diethyl ether and ultrasonically treated to form a uniform mixed solution; 20mL of 3-aminopropyltriethoxysilane (KH-550) was added to the mixed solution, the pH of the system was adjusted to 3, and the reaction was stirred at 50℃ for 2h; after the reaction was completed, the unreacted silane coupling agent was removed by centrifugation and washed with anhydrous ethanol, and the mixture was vacuum dried to obtain hydrophobic nano magnesium oxide powder with a diameter of 50nm; (3) Heat and stir 200 mL of the rice bran wax-emulsifier composite solution prepared in step (1) at 60°C for 1 h, then add 1 g of the hydrophobic nano magnesium oxide powder prepared in step (2), and continue stirring until it is evenly dispersed to obtain a food-grade rice bran wax-based superhydrophobic antibacterial coating.
[0043] Example 3 A method for preparing a food-grade rice bran wax-based superhydrophobic and antibacterial coating includes the following steps: (1) Preparation of rice bran wax-emulsifier composite solution: Dissolve 8g of food-grade rice bran wax in 200mL of methyl acetate and heat until completely melted to obtain rice bran wax solution; add 0.4g of n-octyltriethoxysilane and 0.4g of polydimethylsiloxane to the rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed; (2) Preparation of hydrophobic nano antibacterial powder: 8g of nano zinc oxide was dispersed in 50mL of n-hexane and ultrasonically treated to form a uniform mixed solution; 30mL of 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KA-560) was added to the mixed solution, the pH of the system was adjusted to 4, and the reaction was stirred at 60℃ for 4h; after the reaction was completed, the unreacted silane coupling agent was removed by centrifugation and washed with anhydrous ethanol, and the mixture was vacuum dried to obtain hydrophobic nano zinc oxide powder with a diameter of 80nm. (3) Heat and stir 200 mL of the rice bran wax-emulsifier composite solution prepared in step (1) at 70°C for 2 hours, then add 6 g of the hydrophobic nano zinc oxide powder prepared in step (2) and continue stirring until it is evenly dispersed to obtain a food-grade rice bran wax-based superhydrophobic antibacterial coating.
[0044] Example 4 A method for preparing a food-grade rice bran wax-based superhydrophobic and antibacterial coating includes the following steps: (1) Preparation of rice bran wax-emulsifier composite solution: Dissolve 10g of food-grade rice bran wax in 200mL of propyl acetate and heat until it is completely melted to obtain rice bran wax solution; add 0.5g of glyceryl monostearate and 0.5g of sodium dodecylbenzenesulfonate to the rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed; (2) Preparation of hydrophobic nano antibacterial powder: 6g of nano silver oxide was dispersed in 50mL of cyclohexane and ultrasonically treated to form a uniform mixed solution; 40mL of 3-methacryloyloxypropyltrimethoxysilane (KH-570) was added to the mixed solution, the pH of the system was adjusted to 4, and the reaction was stirred at 70℃ for 6h; after the reaction was completed, the unreacted silane coupling agent was removed by centrifugation and washed with anhydrous ethanol, and then vacuum dried to obtain hydrophobic nano silver oxide powder with a diameter of 60nm; (3) Heat and stir 200 mL of the rice bran wax-emulsifier composite solution prepared in step (1) at 60°C for 1 h, then add 8 g of the hydrophobic nano silver oxide powder prepared in step (2), and continue stirring until evenly dispersed to obtain food-grade rice bran wax-based superhydrophobic antibacterial coating.
[0045] Example 5 A method for preparing a food-grade rice bran wax-based superhydrophobic and antibacterial coating includes the following steps: (1) Preparation of rice bran wax-emulsifier composite solution: Dissolve 10g of food-grade rice bran wax in 200mL of ethyl acetate and heat until it is completely melted to obtain rice bran wax solution; add 1g of polydimethylsiloxane to the rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed. (2) Preparation of hydrophobic nano antibacterial powder: 9g of nano zinc oxide was dispersed in 50mL of n-heptane and ultrasonically treated to form a uniform mixed solution; 50mL of 3-mercaptopropyltrimethoxysilane (KH-590) was added to the mixed solution, the pH of the system was adjusted to 5, and the reaction was stirred at 70℃ for 5h; after the reaction was completed, the unreacted silane coupling agent was removed by centrifugation and washed with anhydrous ethanol, and the mixture was vacuum dried to obtain hydrophobic nano zinc oxide powder with a diameter of 90nm. (3) Heat and stir 200 mL of the rice bran wax-emulsifier composite solution prepared in step (1) at 80°C for 2 hours, then add 4 g of the hydrophobic nano zinc oxide powder prepared in step (2) and continue stirring until it is evenly dispersed to obtain a food-grade rice bran wax-based superhydrophobic antibacterial coating.
[0046] Comparative Example 1 A method for preparing a rice bran wax-emulsifier composite solution coating includes the following steps: Dissolve 10g of food-grade rice bran wax in 200mL of ethyl acetate and heat until completely melted to obtain a rice bran wax solution. Add 1g of polydimethylsiloxane to the rice bran wax solution, heat and stir until a uniformly dispersed rice bran wax-emulsifier composite solution is formed.
[0047] Comparative Example 2 A method for preparing a hydrophobic nano zinc oxide coating includes the following steps: 9g of nano zinc oxide was dispersed in 50mL of n-heptane and sonicated to form a homogeneous mixed solution. 50mL of 3-mercaptopropyltrimethoxysilane (KH-590) was added to the mixed solution to adjust the pH of the system to 5. The mixture was stirred at 70℃ for 5h to obtain a hydrophobic nano zinc oxide coating.
[0048] Application Example 1 The coatings prepared in Examples 1-5 and Comparative Examples 1-2 were applied to the surface of glass substrates to prepare superhydrophobic coatings. The specific method was as follows: the glass substrate to be treated was immersed in the coating solution, and after immersion, it was dried and cured to form a dense antibacterial coating on the surface of the glass substrate.
[0049] Performance testing: (1) Wettability This invention uses a JC2000C1 contact angle measuring instrument to determine wettability: 5 μL of ultrapure water is dropped onto the sample surface, and the measurement is performed after 30 seconds of stabilization. Five different locations are tested in parallel, and the average value of the results is taken. When the static water contact angle is greater than 150°, it is a superhydrophobic surface.
[0050] (2) Determination of surface free energy To study the changes in wettability of sample surfaces, the Owens two-liquid method is often used to determine and calculate the surface free energy of the sample. The determination of surface free energy requires the use of two liquids with different polarities or liquids with significantly different polarities. In this invention, ultrapure water and ethylene glycol are used as model liquids. The surface free energy, polar force, and dispersive force of the two are shown in the table below. The surface tension of the superhydrophobic and oleophobic coating is tested and calculated according to formula (1).
[0051] Where θ is the contact angle between the experimentally measured model droplet and the studied solid surface; γ l and γ s These are the total surface tensions of the liquid being tested and the material being studied, respectively; γ l p and γ l d It is the polarity and dispersive surface tension of the liquid being measured; γ s p and γ s d It studies the polarity and dispersive surface tension of materials; then, it studies the surface tension γ. s Given the droplet radius R, the surface free energy is calculated using formula (2).
[0052] ; (3) Adhesion To test the adhesion of the coating, it was tilted at an angle of ≤10°, and toner was sprinkled on the surface to simulate dust and other contaminants. Then, water droplets were dropped from a certain height, and it was observed whether the water droplets could carry the toner and roll off the coating surface. The amount of toner residue on the coating surface was observed to evaluate its adhesion.
[0053] (4) Antibacterial properties Antibacterial test: The antibacterial properties of the antibacterial coatings of Examples 1-5 and Comparative Examples 1-2 were tested according to QB / T2591-2003 "Antibacterial Plastics - Test Method and Antibacterial Effect". The antibacterial rate was calculated according to formula (3).
[0054] R(%)=(BC)×100 / B(3); Where R is the antibacterial rate (%); B is the average number of recovered bacteria in the blank control sample (CFU / tablet); and C is the average number of recovered bacteria in the antibacterial plastic sample (CFU / tablet).
[0055] Table 1. Test results of antibacterial coatings in Examples 1-5 and Comparative Examples 1-2 As shown in Table 1, the superhydrophobic antibacterial coatings prepared in Examples 1-5 of this invention have static water contact angles greater than 150°, achieving a superhydrophobic state. Based on surface free energy calculations, Example 4 has the lowest surface free energy, at 0.69 J / m². 2 This indicates that the coating has good superhydrophobic properties. The lower the surface free energy of the superhydrophobic coating, the better, because a lower surface free energy results in a larger contact angle between the coating surface and water, thus creating a better superhydrophobic effect. Adhesion and self-cleaning tests revealed that the superhydrophobic antibacterial coatings prepared in Examples 1-5 of this invention have low adhesion and strong self-cleaning properties.
[0056] Figure 1 The contact angles of the antibacterial coatings in Examples 1-5 and Comparative Examples 1-2 are determined by... Figure 1 It can be seen that the water contact angle of Examples 1-5 is all >150°, which belongs to superhydrophobic coatings, and the contact angle is all greater than 130°, indicating that the coating has good oleophobic effect.
[0057] Figure 2 The antibacterial images are for the antibacterial coatings of Examples 1-5 and Comparative Examples 1-2, provided by... Figure 2 It can be seen that the antibacterial coatings of Examples 1-5 have significantly better antibacterial effects than those of Comparative Examples 1-2.
[0058] Figure 3 The image shown is a scanning electron microscope image of the antibacterial coating prepared in Example 4. Figure 3 As can be seen, the coating has a dense and uniformly dispersed micro-nano structure without obvious agglomeration or cracks, indicating that it has good structural stability and can maintain its hydrophobic morphology for a long time, ensuring the durability of its superhydrophobic properties.
[0059] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing a food-grade rice bran wax-based superhydrophobic antibacterial coating, characterized in that, Includes the following steps: (1) Dissolve food-grade rice bran wax in a solvent and heat until melted to obtain a rice bran wax solution; add food-grade emulsifier to the rice bran wax solution, heat and stir to form a uniformly dispersed rice bran wax-emulsifier composite solution; (2) Disperse the nano-antibacterial raw material in a non-polar solvent and sonicate it to form a uniform mixed solution; add a silane coupling agent to the mixed solution, adjust the pH of the system to acidic, and heat and stir; after the reaction is completed, centrifuge, wash and vacuum dry to obtain hydrophobic nano-antibacterial powder; (3) Heat and stir the rice bran wax-emulsifier composite solution obtained in step (1), then add the hydrophobic nano antibacterial powder obtained in step (2), and continue stirring to obtain the food-grade rice bran wax-based superhydrophobic antibacterial coating.
2. The preparation method of the food-grade rice bran wax-based superhydrophobic antibacterial coating according to claim 1, characterized in that, In step (1), the ratio of the food-grade rice bran wax to the solvent is (1-10) g: 200 mL; The mass ratio of the food-grade rice bran wax to the food-grade emulsifier is (1-10):(0.1-1).
3. The preparation method of the food-grade rice bran wax-based superhydrophobic antibacterial coating according to claim 2, characterized in that, The solvent is selected from at least one of ethanol, isopropanol, methyl acetate, ethyl acetate, and propyl acetate; The food-grade emulsifier is selected from at least one of lecithin, stearic acid, sodium lauryl sulfate, glyceryl monostearate, n-octyltriethoxysilane, polydimethylsiloxane, and sodium dodecylbenzenesulfonate.
4. The preparation method of the food-grade rice bran wax-based superhydrophobic antibacterial coating according to claim 1, characterized in that, In step (2), the ratio of the amount of the nano antibacterial raw material, the non-polar solvent and the silane coupling agent is (5-10) g: 50 mL: (10-50) mL.
5. The preparation method of the food-grade rice bran wax-based superhydrophobic antibacterial coating according to claim 1, characterized in that, The hydrophobic nano-antibacterial powder has a particle size of 50-100 nm.
6. The preparation method of the food-grade rice bran wax-based superhydrophobic antibacterial coating according to claim 4, characterized in that, The nano-antibacterial raw material is at least one of nano-zinc oxide, nano-silver oxide and nano-magnesium oxide; The nonpolar solvent is selected from at least one of diethyl ether, n-hexane, cyclohexane, and n-heptane; The silane coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.
7. The preparation method of the food-grade rice bran wax-based superhydrophobic antibacterial coating according to claim 1, characterized in that, In step (2), the pH is adjusted to pH=3-5.
8. The preparation method of the food-grade rice bran wax-based superhydrophobic antibacterial coating according to claim 1, characterized in that, The ratio of the rice bran wax-emulsifier composite solution to the hydrophobic nano-antibacterial powder is 200 mL: (1-10) g.
9. A food-grade rice bran wax-based superhydrophobic and antibacterial coating, characterized in that, It is prepared using the preparation method described in any one of claims 1-8.
10. The application of the food-grade rice bran wax-based superhydrophobic antibacterial coating as described in claim 9 in the preparation of a superhydrophobic coating on a glass substrate surface.