Chemical coupling-free milk-based super-hydrophobic plant pigment coating and alkaline preparation method thereof

Abstract

The invention relates to the technical field of super-hydrophobic materials, and discloses a milk-based super-hydrophobic plant pigment coating without chemical coupling and an alkaline preparation method thereof. The method comprises the following steps: by taking expired milk as a raw material as a protein source, introducing natural pigments with different hues as coloring agents, regulating the environment of a mixed system by using sodium hydroxide to promote complex protein denaturation of the mixed system of the expired milk and the natural pigments, and adding unsaturated fatty acid into the mixed system, and promoting the long alkyl chain and sulfydryl to generate sulfydryl-alkene click chemical reaction, thereby completing the alkaline preparation method of the milk-based super-hydrophobic plant pigment coating without chemical coupling. High-valued utilization of waste resources is achieved through alkali-induced protein recombination, the preparation process is green, simple and convenient, the preparation cost of the super-hydrophobic coating is remarkably reduced, meanwhile, the environmental treatment load is effectively relieved, and the super-hydrophobic coating has huge potential in the fields of bio-based waste recycling, functional coating green preparation and the like. And an innovative path is provided for high-value utilization of waste resources.

Description

Technical Field

[0001] The present invention relates to the technical field of super-hydrophobic materials, in particular to a milk-based super-hydrophobic plant pigment coating that does not require chemical coupling and an alkaline preparation method thereof. Background Art

[0002] Hydrophobic coatings, owing to their unique ability to manipulate surface wettability, have recently become a research hotspot in materials science. The superhydrophobic properties of lotus leaves, remarkably resilient in nature, have inspired the exploration of biomimetic materials. Industrial demands for anti-icing, anti-corrosion, and self-cleaning properties have driven the industrialization of hydrophobic coatings. With the growing demand for protection against extreme environments and the deepening adoption of green manufacturing, the development of novel hydrophobic coatings that combine durability, environmental friendliness, and multifunctionality has become a crucial topic in materials engineering. The precise design and multi-scale coordinated control of surface micro- and nanostructures are crucial in the construction of superhydrophobic coatings. Biomimetic principles are employed to create a surface morphology with a hierarchical roughness (e.g., an ordered arrangement of nanoscale protrusions and micrometer-scale grooves) that significantly enhances the air trapping effect on the surface, thereby improving both water contact angle and rolling angle performance. Furthermore, the synergistic effect of the polymer substrate and low-surface-energy materials (such as fluorosilanes) creates a stable composite interface, limiting water droplet contact to point contacts, thus achieving excellent hydrophobic and self-cleaning properties. Such as invention patent CN114574100A, a kind of super hydrophobic coating and preparation method thereof.The fluorosilicone resin modified epoxy resin obtained combines the excellent properties of fluororesin, silicone resin and epoxy resin, and the paint film obtained therefrom has excellent adhesion, high hardness and excellent hydrophobicity.Invention patent CN118307993A, a kind of super hydrophobic coating and preparation method and application based on low surface energy modified resin.Oligomer is grafted onto resin by curing agent, and resin is subjected to low surface energy modification so that the super hydrophobic coating prepared has excellent hydrophobic and oleophobic properties, adhesion and wear resistance.

[0003] However, current research on superhydrophobic coatings still faces significant environmental and process bottlenecks. Their environmental unfriendliness is primarily reflected in their reliance on petroleum-based raw materials and fluorinated / organic silicon compounds. While these traditional hydrophobic materials achieve excellent water-repellent properties through their low surface energy structures, the extraction of these raw materials exacerbates the depletion of non-renewable resources. Furthermore, the production and degradation of fluorinated compounds can easily generate persistent pollutants, posing an ecological accumulation risk. Regarding the process, most superhydrophobic coatings require complex chemical vapor deposition, sol-gel methods, or plasma treatments to construct hierarchical micro- and nanostructures. This is not only energy-intensive but also involves the use of toxic solvents, leading to increased production costs and environmental impact. More importantly, existing technologies often struggle to balance performance and sustainability. For example, maintaining the long-term stability of superhydrophobicity often requires the introduction of additional non-degradable additives, further exacerbating their lifecycle environmental impact. This linear model of "high carbon footprint preparation, limited lifespan, and difficult recycling" is in sharp conflict with current concepts of green chemistry and the circular economy, necessitating the development of less complex alternative processes based on bio-based raw materials. Patent CN118956261A, an environmentally friendly colored super-hydrophobic coating. Using colorant, alumina aerogel, methyl silicone resin and ethanol as raw materials, combined with a simple dip coating or spraying process, and naturally dried, a colored super-hydrophobic coating can be obtained. It has many advantages such as simple process, easy large-scale production, low cost, and green environmental protection. In addition, by avoiding the use of harmful fluorine compounds, the damage to the environment is significantly reduced, and its applicability is wide, the colors are rich, and the application prospects are very broad. Patent CN110964390A, a bio-based super-hydrophobic coating and its preparation method and application method. A bio-based super-hydrophobic coating, preparation method, and application method are provided. Using resin B as the matrix, pure biological lotus leaf particles are pulverized and ground through a specific process, preserving the lotus leaf's inherent nano-micron dual structure. The topcoat is then applied or sprayed onto the surface to be hydrophobic. The resulting coating exhibits a water contact angle greater than 150°. The synthesis process is simple, low-cost, and green, environmentally friendly, safe, and pollution-free. It can be mass-produced and widely applied to surfaces such as walls, cement, metal, and glass, achieving super-hydrophobicity and self-cleaning properties. This green approach to bio-based micro- and nanostructure construction is a new direction currently awaiting further development. Summary of the Invention

[0004] In view of the defects of the prior art, the present invention provides a kind of milk-based super-hydrophobic plant pigment coating alkaline preparation method without chemical coupling, using expired milk as raw material as protein source, introducing natural pigments of different hues as colorant, utilizing sodium hydroxide to regulate the environment of the mixed system to promote the complex denaturation of protein in expired milk and natural pigment mixed system, unsaturated fatty acids are added to the mixed system, further promoting long alkyl chains and sulfhydryl groups to produce sulfhydryl-ene click chemical reaction, completing the milk-based super-hydrophobic plant pigment coating alkaline preparation method without chemical coupling. The dual transformation of the current super-hydrophobic coating market aesthetic upgrade and application scenario expansion has been solved, a single color has been difficult to meet the visual experience demand under multiple scenarios, and the traditional super-hydrophobic material preparation relies on the use of fluorinated substances and chemical coupling agents, the preparation of super-hydrophobic coatings relies on fluorinated substances and volatile organic solvents to bring adverse effects on human body and ecological environment, relies on specific professional equipment and the preparation cost is high, micro-nano rough structure is easily damaged and the process is complex.

[0005] In order to achieve the above objectives, in the first aspect, the technical solution provided by the present invention is an alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling, and the specific steps are as follows: S1: Fully mix milk and anhydrous ethanol to form a mixed system, and place it in a container for later use; S2: Place the natural pigment in the S1 container and disperse it evenly; S3: Place sodium hydroxide particles in the S2 container, dissolve them fully, and adjust the pH of the mixed system to alkaline; S4: Place unsaturated fatty acids in the S3 container to form a mixed solution and disperse it evenly; the pH of the mixed system is neutral acid (pH 4-6); S5: heating the mixed solution obtained in S4 in an oil bath and stirring the mixture to uniformity; S6: centrifuging the mixed solution obtained in S5 until the supernatant is clear; S7: placing the mixed solution obtained in S6 into a magnetic stirrer and stirring uniformly; S8: After centrifuging and washing the mixed solution obtained in S7, the mixed solution is placed in an oven for drying to obtain a milk-based super-hydrophobic plant pigment coating that does not require chemical coupling.

[0006] Furthermore, in step S1, the volume ratio of milk to anhydrous ethanol is 1:1, the amount of milk used is 100 mL, and the amount of anhydrous ethanol used is 100 mL. The container is a conical flask, and the milk is expired milk, which can effectively save costs. However, milk within its normal shelf life can also be used to prepare the coating. The mixture of expired milk and anhydrous ethanol undergoes complex protein denaturation under certain temperature conditions.

[0007] Furthermore, in step S2, the natural pigment is one or more of rose red, cochineal carmine, curcumin, and indigo. Natural pigments of different hues (rose red, cochineal carmine, curcumin, and indigo) are introduced as colorants. The expired milk and the natural pigments act as active matrices, providing reactive sites for binding with other substances.

[0008] Furthermore, in step S2, the amount of natural pigment used in every 200 mL of the mixed solution of milk and anhydrous ethanol is 1-2 g.

[0009] Furthermore, in step S3, the amount of sodium hydroxide particles used in every 200 mL of the mixed solution of milk and anhydrous ethanol is 0.25 g, so that the particles are fully dissolved and the pH value of the mixed system is adjusted to achieve a more complex denaturation effect.

[0010] Furthermore, in step S4, the volume ratio of the mixed solution of milk and anhydrous ethanol to the unsaturated fatty acid is 20:1. The unsaturated fatty acid is measured and placed in the above-mentioned conical flask to form a mixed solution, and the mixed solution is evenly dispersed to further promote the thiol-ene click chemistry reaction between the long alkyl chain and the thiol group.

[0011] Furthermore, in step S4, the unsaturated fatty acid is at least one of linoleic acid, linolenic acid, arachidonic acid, and oleic acid.

[0012] Furthermore, in step S5, the mixed solution is heated and stirred in an oil bath at a temperature of 60° C., a rotation speed of 30 rpm, and a treatment time of 24 h.

[0013] Furthermore, in step S6, the mixed solution is centrifuged and washed three times with anhydrous ethanol at a centrifugal speed of 10,000 r / min and a processing time of 10 min.

[0014] Furthermore, in step S7, the mixed solution after centrifugal washing is placed in a magnetic stirrer for stirring, and the processing time is 24 hours.

[0015] Furthermore, in step S8, the mixed solution was centrifuged once with anhydrous ethanol at a centrifugal speed of 10,000 r / min for 10 minutes. After centrifugal washing, the mixed solution was placed in an oven at 60°C for 1 hour. Finally, a milk-based superhydrophobic plant pigment coating was produced without the need for chemical coupling.

[0016] Furthermore, the S2 system is neutral; after sodium hydroxide is added to S3, the mixed system is temporarily alkaline; after unsaturated fatty acids are added to S4, the pH of the mixed system is neutral (PH4-6), and the preferred pH of the S4 system is 4.

[0017] In a second aspect, the present invention provides a milk-based super-hydrophobic plant pigment coating that does not require chemical coupling and is prepared using the above-mentioned alkaline preparation method of the milk-based super-hydrophobic plant pigment coating that does not require chemical coupling.

[0018] The above-mentioned alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling first uses expired milk as a protein source, introduces natural pigments of different hues as colorants, and uses expired milk and natural pigments as active matrices. A water-alcohol mixed solution is used as the system solvent to denature the protein. Sodium hydroxide is used to adjust the environment of the mixed system to achieve a more complex protein denaturation effect, resulting in thiol-denatured protein by breaking the disulfide bonds in the protein. At the same time, unsaturated fatty acids are added to the mixed system to promote a thiol-ene click chemistry reaction between the long alkyl chain and the thiol group. Based on this strategy, an expired milk-based super-hydrophobic plant pigment coating without chemical coupling was successfully prepared.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses discarded expired milk as raw material, which is widely available and low-cost. It can not only avoid environmental pollution and food resource waste caused by improper disposal, but also utilize it into products with market value, thus achieving a win-win situation in terms of economic and environmental benefits.

[0020] (2) The present invention adopts a "one-pot" experimental method and innovatively adopts alkaline induction without chemical coupling. The milk-based super-hydrophobic plant pigment coating without chemical coupling can be prepared by only a thiol-ene click chemical reaction between a long alkyl chain and a thiol group. The preparation process is simpler and more environmentally friendly, the reaction conditions are mild, the energy consumption cost is low, and the preparation process is fluorine-free. It greatly reduces the use of chemical solvents and harmful substances, and significantly reduces the process complexity and environmental load.

[0021] (3) This invention adheres to the concept of green development. Through multifunctional design and the integration of rich colors, it addresses the current surge in demand for color diversity and functionality in the pigment market. It not only meets the visual needs of high-end scenes, but also enhances application flexibility, providing the market with an innovative solution that combines aesthetic and practical value. At the same time, it shows great potential in the coatings field and provides an innovative path for the high-value utilization of waste resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the contact angle and rolling angle of the milk-based super-hydrophobic plant pigment coating without chemical coupling shown in Examples 1-7 of the present invention; Figure 2 The dynamic and static anti-wetting behaviors of the seven milk-based super-hydrophobic plant pigment coatings without chemical coupling shown in Examples 1-7 of the present invention; Figure 3Schematic diagram of the milk-based super-hydrophobic plant pigment coating without chemical coupling shown in Example 1 of the present invention under natural light and an ultraviolet photoluminescence effect diagram; Figure 4 This is the excitation spectrum of the milk-based super-hydrophobic plant pigment coating without chemical coupling shown in Example 1 of the present invention; Figure 5 This is the emission spectrum of the milk-based super-hydrophobic plant pigment coating without chemical coupling shown in Example 1 of the present invention; Figure 6 The UV protection factor (UPF) of the milk-based superhydrophobic plant pigment coating without chemical coupling and the UV protection factor of the unsprayed fabric shown in Examples 1-7 of the present invention; Figure 7 UVA and UVB of the milk-based super-hydrophobic plant pigment coating without chemical coupling and the unsprayed fabric as shown in Examples 1-7 of the present invention; Figure 8 This is a diagram showing the delayed freezing effect of the milk-based super-hydrophobic plant pigment coating without chemical coupling shown in Example 1 of the present invention, which is an original fabric coating and a fabric coating sprayed with the milk-based super-hydrophobic plant pigment coating without chemical coupling; Figure 9 The stability of the contact angle and rolling angle of the milk-based super-hydrophobic plant pigment coating without chemical coupling under high-temperature heating conditions shown in Example 1 of the present invention; Figure 10 The stability of the contact angle and rolling angle of the milk-based superhydrophobic plant pigment coating in a refrigerated environment without chemical coupling as shown in Example 7 of the present invention; Figure 11 This is an optical photograph of a fabric coating containing 2 g of the natural pigment carmine in the milk-based super-hydrophobic plant pigment coating that does not require chemical coupling as shown in Example 8 of the present invention; Figure 12 Schematic diagram of the contact angle and sliding angle of the milk-based superhydrophobic plant pigment coating without chemical coupling shown in Examples 9-11 of the present invention. DETAILED DESCRIPTION

[0023] In order to clearly and comprehensively show the purpose, core technology and advantage of the milk-based super-hydrophobic plant pigment coating prepared by the present invention without chemical coupling, below in conjunction with specific embodiment and with reference to accompanying drawing, and according to relevant experimental data, the present invention is expanded to elaborate in more detail. In the description process of specific embodiment, the details such as various experimental operation steps, raw material selection standard and reaction condition control are listed in detail, so that the present invention is fully understood. But the present invention can be implemented in a lot of other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiment disclosed below.

[0024] The present invention's patent innovatively adopts alkaline-induced technology to prepare super-hydrophobic coatings, completely abandons the use of traditional chemical coupling agents, and significantly reduces process complexity and environmental load. Using expired milk as raw material as a protein source, introducing natural pigments of different hues as colorants, using a water-alcohol mixed solution as a system solvent, and using sodium hydroxide to regulate the environment of the mixed system to promote the complex denaturation of proteins in the expired milk and natural pigment mixed system, and the sulfhydryl denatured protein obtained by the rupture of disulfide bonds in the protein. At the same time, unsaturated fatty acids are added to the mixed system, further promoting the long alkyl chain and the sulfhydryl group to undergo sulfhydryl-ene click chemical reaction, and preparing a milk-based super-hydrophobic plant pigment coating without chemical coupling, constructing a new green coating system with both environmental friendliness, functionalization and aesthetic value, showing great potential in the field of coatings, and providing an innovative path for the high-value utilization of waste resources.

[0025] Example 1 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 1 g of cochineal red into the conical flask prepared in step 1 and shake to disperse it evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0026] Example 2 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 0.35 g of rose bengal and 0.65 g of curcumin into the conical flask prepared in step 1 and shake to disperse them evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0027] Example 3 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol, mix thoroughly to form a mixed system, and pour into a conical flask for later use; Step 2: Weigh 0.35 g of cochineal carmine and 0.65 g of curcumin into the conical flask prepared in step 1 and shake to evenly disperse them. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0028] Example 4 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 1 g of curcumin into the conical flask prepared in step 1 and shake to disperse it evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0029] Example 5 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 0.15 g of indigo and 0.85 g of curcumin into the conical flask prepared in step 1 and shake to disperse evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0030] Example 6 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 1 g of indigo and add it to the conical flask prepared in step 1. Shake to disperse it evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0031] Example 7 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 0.15 g of indigo and 0.85 g of cochineal red into the conical flask prepared in step 1 and shake to disperse evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: Centrifuge the mixed solution of step 7 again, the centrifugal speed is 10000 rpm, the time is 10 minutes, and the mixed solution after centrifugal washing is placed in an oven for drying, the oven temperature is 60 ℃, and the treatment time is 1 hour to obtain a milk-based super-hydrophobic plant pigment coating that does not require chemical coupling.

[0032] Example 8 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol, mix thoroughly to form a mixed system, and pour into a conical flask for later use; Step 2: Weigh 2 g of cochineal red into the conical flask prepared in step 1 and shake to disperse it evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linoleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0033] Example 9 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 1 g of indigo and add it to the conical flask prepared in step 1. Shake to disperse it evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of arachidonic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0034] Example 10 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 1 g of indigo and add it to the conical flask prepared in step 1. Shake to disperse it evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of oleic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0035] Example 11 The present invention provides an alkaline preparation method for a milk-based super-hydrophobic plant pigment coating without chemical coupling, which comprises the following steps: Step 1: Measure 100 mL of expired milk and 100 mL of anhydrous ethanol and mix them thoroughly to form a mixed system. Pour the mixture into a conical flask and set aside. Step 2: Weigh 1 g of indigo and add it to the conical flask prepared in step 1. Shake to disperse it evenly. Step 3: Weigh 0.25 g of sodium hydroxide pellets and add them to the conical flask prepared in step 2. Shake to dissolve evenly. Step 4: Measure 10 mL of linolenic acid and add it to the conical flask in step 3 to disperse it evenly; Step 5: Place the mixed solution in the conical flask in step 4 in an oil bath and heat and stir evenly. The oil bath temperature is 60°C, the stirring speed is 30 rpm, and the reaction time is 24 h. Step 6: The mixed solution after the reaction in step 5 was centrifuged and washed. The centrifugal washing was performed by centrifuging once and washing with anhydrous ethanol three times until the supernatant was clear. The centrifugation speed was 10,000 rpm and the time was 10 min. Step 7: Place the mixed solution after centrifugation and washing in step 6 on a magnetic stirrer for 24 hours to further ensure that the components are evenly dispersed; Step 8: The mixed solution of step 7 was centrifuged and washed once again, the centrifugal speed was 10000 rpm, and the time was 10 minutes. The mixed solution after centrifugal washing was placed in an oven for drying at an oven temperature of 60 ° C for 1 hour to obtain a milk-based super-hydrophobic plant pigment coating without chemical coupling.

[0036] Table 1 is a summary table of the mass of materials added in Examples 1 to 8;

[0037] It should also be noted that the preparation steps for Examples 1-8 are essentially the same, with only the proportions of certain natural pigments being varied. This allows for the production of milk-based, super-hydrophobic plant pigment coatings of varying colors without the need for chemical coupling. The products of Examples 1-7 were tested for wettability, UV photoluminescence and fluorescence, UV resistance, delayed freezing, and wettability stability under refrigeration and heating conditions, revealing minimal differences in product characteristics. Examples 9-11 follow essentially the same preparation steps as Examples 1-8, with the exception of alternative unsaturated fatty acids (arachidonic acid, oleic acid, and linolenic acid).

[0038] The following is an example of the test process of a fabric sprayed with a milk-based super-hydrophobic plant pigment coating that does not require chemical coupling.

[0039] 1. Determination of the wetting properties of milk-based super-hydrophobic plant pigment coatings without chemical coupling and schematic diagram, see Figure 1-2 .

[0040] See Figure 1 The test results of the milk-based super-hydrophobic plant pigment coatings prepared in Examples 1-7 without chemical coupling were sprayed on cotton woven fabrics using a spraying process. The specific method for determining the wetting properties includes: S1: The fabric coatings of Examples 1-7 were placed on a test bench using a JC2000D1 contact angle meter to measure the static contact angles of the fabric coatings. S2: 5 μL of deionized water was added to five different locations of the milk-based superhydrophobic plant pigment coating without chemical coupling, and the contact angle was measured and the average value was calculated to obtain the static contact angle; S3: Adjust the tilt angle of the contact angle measuring instrument angle table and fix it. The angle at which 10 μL of deionized water can roll off when dropped at three different locations on the fabric coating is the rolling angle.

[0041] See also Figure 1 As shown, the static contact angles of milk-based super-hydrophobic plant pigment coating embodiments 1-7 without chemical coupling are 153.6°, 153.7°, 154.7°, 154.6°, 152.1°, 152.5°, and 151.4°, respectively, all of which are above 150°. The sliding angles of embodiments 1-7 are 7.5°, 6°, 8°, 9°, 9°, 6°, and 9.5°, respectively, and the sliding angles are all below 10°, which indicates that the product has good super-hydrophobic properties.

[0042] See also Figure 2As shown, when a drop of deionized water is dropped on the surface of the milk-based super-hydrophobic plant pigment coating that does not require chemical coupling, it can be clearly observed that the deionized water does not infiltrate or spread on the surface of the fabric coating, and can maintain a spherical shape; when the fabric coating is placed at an angle, it is observed whether the water drop can roll off the surface of the fabric coating smoothly without being stained by the droplets, which shows that the product has good moisture resistance.

[0043] 2. Schematic diagram of ultraviolet photoluminescence of milk-based super-hydrophobic plant pigment coating without chemical coupling, and fluorescence characteristics of excitation spectrum and emission spectrum of milk-based super-hydrophobic plant pigment coating without chemical coupling, see Figure 3-5 .

[0044] See also Figure 3 As shown, the milk-based super-hydrophobic plant pigment coating obtained in Example 1 without chemical coupling was placed under natural light and ultraviolet light, respectively. Figure 3a shows that the color of Example 1 under natural light is pink, and Figure 3b shows that Example 1 emits blue-purple light when irradiated with 365 nm ultraviolet light in an ultraviolet dark box. It can be observed that the obtained product has ultraviolet photoluminescence properties.

[0045] See also Figure 4 As shown, the milk-based super-hydrophobic plant pigment coating without chemical coupling obtained in Example 1 was subjected to fluorescence spectrum testing using a steady-state fluorescence spectrometer to analyze its fluorescence characteristics. The plant pigment coating in Example 1 was tested by excitation spectrum at a fixed emission wavelength, and the fluorescence intensity of Example 1 was 3170 du.

[0046] See also Figure 5 As shown, the milk-based super-hydrophobic plant pigment coating obtained in Example 1 without chemical coupling was tested by emission spectroscopy at a fixed excitation wavelength, and the fluorescence intensity of Example 1 was 6410 du, which shows that the product has strong ultraviolet photoluminescence properties.

[0047] 3. UV protection properties of milk-based superhydrophobic plant pigment coatings without chemical coupling, see Figure 6-7 .

[0048] See also Figure 6 As shown, the ultraviolet protection performance of Examples 1-7 was tested using a YG912E textile anti-ultraviolet performance tester. It can be seen that the ultraviolet protection factor (UPF) of the fabric not sprayed with the milk-based super-hydrophobic plant pigment coating that does not require chemical coupling is 37.2, and the ultraviolet protection factors (UPF) of the fabrics sprayed with the milk-based super-hydrophobic plant pigment coating that does not require chemical coupling of Examples 1-7 are 201.1, 4770.8, 451.2, 1013.8, 776.5, 536.3, and 1327.1, respectively.

[0049] See also Figure 7 As shown, the UV protection performance of Examples 1-7 was tested using a YG912E textile anti-UV performance tester, and it can be seen that the long-wave ultraviolet transmittance (UVA, 315-400 nm) of the fabric not sprayed with the milk-based super-hydrophobic plant pigment coating without chemical coupling is 5.105, and the long-wave ultraviolet transmittance (UVA, 315-400 nm) of the fabric sprayed with the milk-based super-hydrophobic plant pigment coating without chemical coupling of Examples 1-7 are 1.210, 0.030, 0.260, 0.090, 0.135, 0.325, and 0.280, respectively.

[0050] According to my country's national standards: a product can only be called an "anti-ultraviolet product" if its UPF value is greater than 40 and its UVA transmittance is less than 5%. Figure 6-7 As shown, it can be seen that the UPF value of the fabric sprayed with milk-based superhydrophobic plant pigment coating without chemical coupling is much greater than 40, and the UVA transmittance is much less than 5%. Compared with the original sample, the UPF value is significantly increased, and the UVA transmittance is significantly reduced, and the ability to block ultraviolet radiation is enhanced.

[0051] 4. Determination of the delayed freezing properties of milk-based superhydrophobic plant pigment coatings without chemical coupling, see Figure 8 .

[0052] See also Figure 8 As shown, the delayed freezing performance of the milk-based super-hydrophobic plant pigment fabric coating without spraying and chemical coupling and the milk-based super-hydrophobic plant pigment fabric coating without chemical coupling in Example 1 were measured in an extremely cold environment. The freezing process and freezing time of droplets on different surfaces were recorded using a high-definition video microscope. The time it takes for the droplet to transform from liquid to solid when it contacts the surface can be observed. Figure 8 a shows the original fabric coating surface. 10 μL of deionized water was pipetted onto the surface. Re-glow occurred at 270 s, and ice tips appeared at 318 s due to freezing of the droplet. Figure 8 b shows that the fabric coating of Example 1 shows re-glow phenomenon at 576 s, and ice tips appear at 687 s due to freezing of droplets. This shows that the product has the ability to delay freezing in cold environments.

[0053] 5. Determination of the stability characteristics of milk-based super-hydrophobic plant pigment coatings in different extreme environments without chemical coupling, see Figure 9-10 .

[0054] See also Figure 9As shown, the milk-based super-hydrophobic plant pigment coating without chemical coupling of Example 1 was subjected to a high-temperature heating stability test. The fabric coating of Example 1 was heated in an oven at 120°C, and the wetting performance of the fabric coating of Example 1 was tested every 2 hours. After 10 hours of cyclic high-temperature treatment, it was observed that the contact angle decreased from 153.9° to 151.6°, and the rolling angle increased from 7.5° to 9.5°. The contact angles were both greater than 150°, and the rolling angles were both less than 10°, indicating excellent high-temperature durability.

[0055] See also Figure 10 As shown, the milk-based super-hydrophobic plant pigment coating without chemical coupling of Example 7 was subjected to a low-temperature refrigeration stability test. The fabric coating of Example 7 was refrigerated in a cold environment of -15°C, and the wetting performance of the fabric coating of Example 7 was tested every 2 hours. After cyclic low-temperature refrigeration treatment for 12 hours, it can be observed that its contact angle decreased from 155.2° to 150.4°, and the rolling angle increased from 4.5° to 9°. The contact angles were both greater than 150°, and the rolling angles were both less than 10°, indicating excellent low-temperature durability.

[0056] See also Figure 11 As shown, this is an optical photograph of a fabric coating in which the natural pigment cochineal red is used in a milk-based superhydrophobic plant pigment coating without chemical coupling in Example 8, so the amount of natural pigment used can range from 1 to 2 g.

[0057] See also Figure 12 As shown, the milk-based super-hydrophobic plant pigment coating without chemical coupling obtained in Examples 9-11 in which the unsaturated fatty acids are arachidonic acid, oleic acid, and linolenic acid, is sprayed on a cotton woven fabric using a spraying process. The test results show that the static contact angles of Examples 8-10 are 156.8°, 154.7°, and 157.3°, respectively. The contact angles are all above 150°, and the rolling angles of Examples 8-10 are 4.8°, 5°, and 5°, respectively. The rolling angles are all below 10°, which indicates that the product has good super-hydrophobic properties.

[0058] In addition, it should be understood that the above embodiments are only used to explain the present invention in detail, and the present invention is not limited to the above detailed methods. For those skilled in the art, any improvements to the present invention, equivalent replacements of various raw materials for the products of the present invention, selection of specific methods, etc., within the spirit and principles of the present invention, should be included in the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing an alkaline milk-based super-hydrophobic plant pigment coating without chemical coupling, characterized in that: The following steps are involved: S1: Fully mix milk and anhydrous ethanol to form a mixed system, and place it in a container for later use; S2: Place the natural pigment in a container and disperse it evenly; S3: placing sodium hydroxide particles in a container, dissolving them fully, and adjusting the pH of the mixed system to alkaline; S4: placing unsaturated fatty acids in a container to form a mixed solution, and uniformly dispersing the mixed solution; the pH of the mixed system is neutral acid; S5: heating the mixed solution obtained in S4 in an oil bath and stirring the mixture to uniformity; S6: centrifuging the mixed solution obtained in S5 until the supernatant is clear; S7: placing the mixed solution obtained in S6 into a magnetic stirrer and stirring uniformly; S8: After centrifuging and washing the mixed solution obtained in S7, the mixed solution is placed in an oven for drying to obtain a milk-based super-hydrophobic plant pigment coating that does not require chemical coupling.

2. the milk-based super-hydrophobic plant pigment coating alkaline preparation method without chemical coupling according to claim 1, is characterized in that: In step S1, the volume ratio of the milk to anhydrous ethanol is 1:1, the amount of milk is 100 mL, and the amount of anhydrous ethanol is 100 mL; the milk is expired milk.

3. The alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling according to claim 1, wherein: In step S2, the natural pigment is one or more of rose red, cochineal red, curcumin, and indigo; and the amount of the natural pigment used in each 200 mL mixed solution of milk and anhydrous ethanol is 1-2 g.

4. The alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling according to claim 1, wherein: In step S3, the amount of sodium hydroxide particles used in every 200 mL of the mixed solution of milk and anhydrous ethanol is 0.25 g.

5. The alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling according to claim 1, wherein: In step S4, the volume ratio of the mixed solution of milk and anhydrous ethanol to the unsaturated fatty acid is 20:1, wherein the unsaturated fatty acid is at least one of linoleic acid, linolenic acid, arachidonic acid, and oleic acid.

6. The alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling according to claim 1, characterized in that: In step S5, the mixed solution is heated and stirred in an oil bath at a temperature of 60° C., a rotation speed of 30 rpm, and a treatment time of 24 h.

7. The alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling according to claim 1, characterized in that: In step S6, the mixed solution is centrifuged and washed three times with anhydrous ethanol at a centrifugal speed of 10,000 r / min for 10 min.

8. The alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling according to claim 1, characterized in that: In step S7, the mixed solution after centrifugal washing is placed in a magnetic stirrer for stirring for 24 hours.

9. The alkaline preparation method of milk-based super-hydrophobic plant pigment coating without chemical coupling according to claim 1, characterized in that: In step S8, the mixed solution is centrifuged and washed once with anhydrous ethanol at a centrifugal speed of 10,000 r / min for 10 min. After centrifugal washing, the mixed solution is placed in an oven at a temperature of 60° C. for 1 h.

10. A milk-based super-hydrophobic plant pigment coating without chemical coupling, characterized in that: A milk-based super-hydrophobic plant pigment coating that does not require chemical coupling is prepared by the alkaline preparation method of a milk-based super-hydrophobic plant pigment coating that does not require chemical coupling as described in any one of claims 1 to 9.

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