Self-roughening super-hydrophobic waterborne polyurethane matte coating as well as preparation method and application thereof

Abstract

The invention discloses a self-roughening super-hydrophobic waterborne polyurethane matte coating as well as a preparation method and application thereof, and relates to the technical field of coatings. The coating comprises the following components in percentage by weight: 1-15% of waterborne polyurethane, 0.5-20% of alkyl guanidine, 1-9% of silicon resin emulsion and the balance of water. In the preparation process, hydrogen bonds of carbonyl of waterborne polyurethane and guanidyl in alkyl guanidine in the film forming process are ingeniously utilized to induce rapid accumulation, self-roughening of the coating is achieved, an alkane chain in alkyl guanidine and silicon resin provide hydrophobic groups, and conversion of the waterborne polyurethane coating from hydrophilicity to hydrophobicity is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a self-roughing super-hydrophobic waterborne polyurethane matte coating, a preparation method and application thereof. BACKGROUND

[0002] Waterborne coatings use water as a solvent or dispersant, compared with traditional solvent-based coatings using organic solvents as a dispersion medium, effectively reducing the use of organic solvents, greatly reducing VOC emissions, and accelerating the use of green and environmentally friendly waterborne coatings. Among them, waterborne polyurethane emulsion as an important low VOC waterborne coating has good adhesion, excellent acid and alkali corrosion resistance, and excellent flexibility, and is widely used in materials such as metal, wood board, floor paint, etc. However, in order to disperse well in water, most waterborne polyurethane molecular chains contain hydrophilic groups, and are linear structures, resulting in poor water resistance of the dried coating, and color change, softening, blistering, peeling and other undesirable behaviors. Hydrophobic modification can improve the contact angle of the coating to resist liquid infiltration on the surface. If the super-hydrophobic effect is achieved, not only the water resistance of the coating can be further improved, but also other multifunctional properties such as self-cleaning, anti-fouling, anti-icing, etc. can be obtained, and the application scenarios of waterborne polyurethane are broadened.

[0003] Super-hydrophobicity must have both micro-nano rough structure and low surface energy material. The micro-nano rough structure is generally constructed by doping micro-nano particles, and the low surface energy modified inorganic nano particles are blended with waterborne polyurethane emulsion to prepare an integrated coating. However, due to the large difference in surface tension with water, there are usually problems such as difficulty in dispersing low surface energy particles, easy agglomeration, and poor emulsion stability. To achieve good hydrophobic effect, it is necessary to keep the waterborne polyurethane addition amount low and add fluorocarbon surfactants and other auxiliary dispersants, and in the process of use, inorganic nano particles are prone to peeling off, which damages the durability and brings risks to the human body and the environment. Directly grafting modification to the polyurethane molecular chain has limited reduction of the surface energy of the coating, and the roughness of the coating is insufficient, making it difficult to achieve super-hydrophobicity. Self-roughing structure can be generated through intermolecular interaction of organic molecules, which can achieve super-hydrophobic modification of the coating by low surface energy material modification without introducing any inorganic nano particles. In the prior art, a self-roughing porous network super-hydrophobic polyester fabric is prepared by inducing phase separation through the mutual exchange of polymer matrix between solvent / non-solvent, but this method uses a full organic solvent system, which is harmful to the human body and the environment. The prior art also discloses that a self-roughing structure can be constructed on the surface of the fabric based on a low surface energy silicone material, which does not need to introduce inorganic nano particles, avoiding the harm to the human body and the environment caused by the peeling off of inorganic nano particles. However, the preparation process is complex and still requires the use of a large amount of organic solvents. In view of the above problems, a self-roughing super-hydrophobic waterborne polyurethane coating is designed and prepared, which is of great significance for promoting the development of green and environmentally friendly and high-performance coatings. SUMMARY

[0004] In view of the above background, the present application provides a self-roughening super-hydrophobic waterborne polyurethane matte paint, a preparation method and application thereof. The method utilizes the hydrogen bond-induced rapid accumulation of carbonyl groups in waterborne polyurethane and guanidinium groups in alkyl guanidine during film formation to achieve self-roughening of the coating. The alkane chains in alkyl guanidine and silicone resin provide hydrophobic groups, promoting the transformation of waterborne polyurethane coating from hydrophilic to hydrophobic.

[0005] The first object of the present application is to provide a self-roughening super-hydrophobic waterborne polyurethane matte paint, comprising the following components by mass percentage: waterborne polyurethane 1-15%, alkyl guanidine 0.5-20%, silicone resin emulsion 1-9%, and the balance being water.

[0006] Preferably, the waterborne polyurethane is cationic waterborne polyurethane or non-ionic waterborne polyurethane.

[0007] Preferably, the silicone resin emulsion includes one or more of PDMS emulsion, methylphenyl silicone resin emulsion, epoxy-modified silicone resin emulsion, acrylic silicone emulsion, and polyether-modified silicone resin emulsion.

[0008] Preferably, the alkyl guanidine includes one or more of methyl guanidine, ethyl guanidine, dimethyl guanidine, tetramethyl guanidine, pentaalkyl guanidine, dodecyl guanidine, polyhexamethylene biguanide, and polyaminopropyl biguanide.

[0009] The second object of the present application is to provide a preparation method of a self-roughening super-hydrophobic waterborne polyurethane matte paint, comprising the following steps: mixing the waterborne polyurethane emulsion and the aqueous alkyl guanidine solution, adding the silicone resin emulsion, and uniformly mixing at room temperature and normal pressure to obtain the self-roughening super-hydrophobic waterborne polyurethane matte paint; wherein the mass percentage of the waterborne polyurethane in the waterborne polyurethane emulsion and the alkyl guanidine in the aqueous alkyl guanidine solution in the self-roughening super-hydrophobic waterborne polyurethane matte paint is 1-15% and 0.5-20%, respectively; The amount of the silicone resin emulsion added is 1-9 wt.%.

[0010] Preferably, the solid content of the waterborne polyurethane in the waterborne polyurethane emulsion is 2-30 wt.% and the solid content of the alkyl guanidine in the aqueous alkyl guanidine solution is 1-40 wt.%.

[0011] Preferably, the silicone resin emulsion is an emulsion formed by emulsifying silicone resin microparticles with water as the dispersion medium; and the silicone resin includes one or more of PDMS, methylphenyl silicone resin, epoxy-modified silicone resin, acrylic silicone, and polyether-modified silicone resin.

[0012] The third object of the present application is to provide an application of the self-rough super-hydrophobic waterborne polyurethane matte coating in modification of a substrate surface.

[0013] The fourth object of the present application is to provide a coating prepared by using the self-rough super-hydrophobic waterborne polyurethane matte coating, which is prepared by coating the self-rough super-hydrophobic waterborne polyurethane matte coating on a rough substrate or a smooth substrate by spraying, brushing or dipping, and curing at 80-120℃ for 3-9 hours.

[0014] Preferably, when the coating is coated on a rough substrate, the water contact angle of the coating is ≥150° and the glossiness is ≤30°; when the coating is coated on a smooth substrate, the water contact angle of the coating is ≥120° and the glossiness is ≤30°.

[0015] Compared with the prior art, the present application has the following beneficial effects: The present application provides a self-rough super-hydrophobic waterborne polyurethane matte coating, a preparation method and an application thereof. The present application uses a waterborne polyurethane emulsion with a chemical cross-linking structure of multi-hydroxyl functionality, and introduces a water-soluble alkyl guanidine molecule. The physical cross-linking structure based on the guanidino-carbonyl hydrogen bond induces the waterborne polyurethane to quickly accumulate and construct a self-rough structure during the film-forming process, and the introduction of a silicone emulsion reduces the surface energy, thereby obtaining a uniform and stable dispersion super-hydrophobic waterborne polyurethane coating.

[0016] The self-rough super-hydrophobic waterborne polyurethane matte coating provided by the present application has waterborne and environmentally friendly properties. The preparation method is simple, and the hydrogen bond between the carbonyl group of the waterborne polyurethane and the guanidino group in the alkyl guanidine is ingeniously utilized to induce quick accumulation during the film-forming process, so as to realize self-roughness of the coating. The alkane chain in the alkyl guanidine and the silicone provide hydrophobic groups, which promote the transformation of the waterborne polyurethane coating from hydrophilic to hydrophobic. The prepared super-hydrophobic composite coating can be applied to various substrates, which not only endows the substrate with excellent waterproof performance and anti-fouling performance, but also has certain antibacterial performance due to the excellent broad-spectrum antibacterial property of guanidine salt. In addition, the coating also has certain mechanical stability and chemical stability, thereby realizing the preparation of multifunctional waterborne polyurethane coating. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the infrared spectrum comparison between the pure waterborne polyurethane coating and the self-rough super-hydrophobic waterborne polyurethane matte coating in Example 2. Figure 2 It is the scanning electron microscope image and water contact angle of the glass surface hydrophobic waterborne polyurethane coating self-rough structure in Example 2. Figure 3 It is the scanning electron microscope image of the cotton fabric surface after applying the self-rough super-hydrophobic waterborne polyurethane matte coating in Example 3. Figure 4Water contact angle of the cotton fabric surface in Example 3 after applying the self-roughening super-hydrophobic waterborne polyurethane matte coating; Figure 5 Wettability resistance of the cotton fabric surface in Example 3 after applying the self-roughening super-hydrophobic waterborne polyurethane matte coating; Figure 6 Contact angle of the super-hydrophobic modified cotton fabric after the mechanical and chemical stability test in Example 4; Figure 7 Wettability resistance of the wood surface in Example 5 after applying the self-roughening super-hydrophobic waterborne polyurethane matte coating; Figure 8 Wettability resistance of the gauze surface in Example 6 after applying the self-roughening super-hydrophobic waterborne polyurethane matte coating to water solution and artificial blood; Figure 9 Water contact angle of the self-roughening waterborne polyurethane coating formed by curing the prepared coating on the gauze surface in Example 8. DETAILED DESCRIPTION

[0018] In order to enable the technical personnel to better understand the technical solutions of the present application, the present application is further described below in conjunction with specific embodiments and drawings, but the embodiments are not as a limitation on the present application.

[0019] The purpose of the present application is to provide a self-roughening super-hydrophobic waterborne polyurethane matte coating, its preparation method and application. The coating does not need to introduce any inorganic nanoparticles, and can realize the stable preparation of the self-roughening super-hydrophobic waterborne polyurethane matte coating with multifunctionality.

[0020] In order to achieve the above purpose, the first aspect of the present application provides a self-roughening super-hydrophobic waterborne polyurethane matte coating, characterized in that it comprises the following components in mass percentage: waterborne polyurethane 1-15%, alkyl guanidine 0.5-20%, silicone resin emulsion 1-9%, and the balance is water.

[0021] The present application adopts waterborne polyurethane emulsion with multi-hydroxyl functionality and chemical cross-linking structure, and introduces water-soluble alkyl guanidine molecules. The physical cross-linking structure based on guanidine-carbonyl hydrogen bond induces the rapid accumulation of waterborne polyurethane during film formation to construct a self-roughening structure, and the introduction of silicone resin emulsion reduces the surface energy, and obtains a uniform and stable dispersion super-hydrophobic waterborne polyurethane coating. The coating can be applied on the surface of various substrates (cotton fabric, glass, wood, metal, concrete) by spraying, dipping and other methods to realize self-roughening construction, improve its hydrophobicity, and at the same time impart matte properties.

[0022] The waterborne polyurethane is a cationic waterborne polyurethane or a non-ionic waterborne polyurethane.

[0023] The silicone resin emulsion includes one or more of a PDMS emulsion, a methylphenyl silicone resin emulsion, an epoxy-modified silicone resin emulsion, an acrylic silicone emulsion, and a polyether-modified silicone resin emulsion.

[0024] The alkyl guanidine includes one or more of methyl guanidine, ethyl guanidine, dimethyl guanidine, tetramethyl guanidine, pentaalkyl guanidine, dodecyl guanidine, polyhexamethylene biguanide, and polyaminopropyl biguanide.

[0025] The second aspect of the present application provides a preparation method of a self-rough super-hydrophobic waterborne polyurethane matte paint, including the following steps: The waterborne polyurethane emulsion and the alkyl guanidine aqueous solution are mixed, and the silicone resin emulsion is added, and the mixture is uniformly mixed at room temperature and normal pressure to obtain the self-rough super-hydrophobic waterborne polyurethane matte paint. The mass percentage of the waterborne polyurethane in the waterborne polyurethane emulsion and the mass percentage of the alkyl guanidine in the alkyl guanidine aqueous solution in the self-rough super-hydrophobic waterborne polyurethane matte paint are 1-15% and 0.5-20%, respectively. The addition amount of the silicone resin emulsion is 1-9 wt.%.

[0026] The method provided by the present application is simple, time-saving, and does not require complex equipment and steps.

[0027] The solid content of the polyurethane in the waterborne polyurethane emulsion is 2-30 wt.%; and the solid content of the alkyl guanidine in the alkyl guanidine aqueous solution is 1-40 wt.%.

[0028] The silicone resin emulsion is an emulsion formed by emulsifying silicone resin particles with water as a dispersion medium; The silicone resin includes one or more of PDMS, methylphenyl silicone resin, epoxy-modified silicone resin, acrylic silicone, and polyether-modified silicone resin.

[0029] Exemplarily, a self-rough super-hydrophobic waterborne polyurethane matte paint is prepared according to the following method: The waterborne polyurethane emulsion and the alkyl guanidine aqueous solution are mixed in a certain proportion, and a certain amount of silicone resin emulsion is added, and the mixture is uniformly dispersed by stirring at room temperature and normal pressure to obtain the self-rough super-hydrophobic waterborne polyurethane matte paint, wherein the mass percentage of the waterborne polyurethane and the alkyl guanidine in the super-hydrophobic paint is 1-15% and 0.5-20%, respectively, the addition amount of the silicone resin emulsion is 1-9 wt.%, and the balance is water.

[0030] The three solutions are all aqueous solutions, which ensure uniform dispersion in water and stable storage.

[0031] The waterborne polyurethane emulsion is one of a cationic waterborne polyurethane and a non-ionic waterborne polyurethane.

[0032] The polyurethane solid content in the aqueous polyurethane emulsion is 2-30 wt.%, preferably 5-10 wt.%.

[0033] The alkyl guanidine solid content in the aqueous alkyl guanidine solution is 1-40 wt.%, preferably 1-10 wt.%.

[0034] The silicone resin emulsion is an environmentally friendly functional emulsion formed by microparticulating and emulsifying an organic silicone resin with water as the dispersion medium, including but not limited to PDMS emulsion, methyl phenyl silicone resin emulsion, epoxy modified silicone resin emulsion, acrylic silicone emulsion, and polyether modified silicone resin emulsion.

[0035] The alkyl guanidine is an organic cationic compound formed by connecting a guanidine group and an alkyl chain, including but not limited to methyl guanidine, ethyl guanidine, dimethyl guanidine, tetramethyl guanidine, pentaalkyl guanidine, dodecyl guanidine, polyhexamethylene biguanide, and polyaminopropyl biguanide.

[0036] The stirring is one or a combination of two or more of mechanical stirring, magnetic stirring, ultrasonic stirring, and oscillation stirring.

[0037] The third aspect of the present application provides an application of the self-rough super-hydrophobic aqueous polyurethane matte coating in modifying the surface of a substrate.

[0038] The fourth aspect of the present application provides a coating layer prepared by using the self-rough super-hydrophobic aqueous polyurethane matte coating, which is prepared by coating the self-rough super-hydrophobic aqueous polyurethane matte coating on a rough substrate or a smooth substrate by spraying, brushing, or dipping, and then curing at 80-120 DEG C for 3-9 h.

[0039] The water contact angle of the coating layer coated on the rough substrate is greater than or equal to 150 DEG, and the glossiness is less than or equal to 30 DEG; the water contact angle of the coating layer coated on the smooth substrate is greater than or equal to 120 DEG, and the glossiness is less than or equal to 30 DEG.

[0040] The self-rough super-hydrophobic matte polyurethane coating is coated on a rough substrate such as fabric, gauze, wood, concrete, and paper by spraying, brushing, or dipping, and then dried and cured to obtain a self-rough super-hydrophobic matte coating layer, the water contact angle of which is greater than or equal to 150 DEG, and the glossiness is less than or equal to 30 DEG; the curing temperature is in the range of 80-120 DEG C, and the curing time is 3-9 h, and the higher the temperature, the shorter the curing time.

[0041] The self-roughening super-hydrophobic waterborne matte polyurethane coating is coated on a smooth substrate such as glass or metal by spraying, brushing or dipping, and after drying and curing, a self-roughening super-hydrophobic matte coating is obtained, with a water contact angle of greater than or equal to 120 degrees and a glossiness of less than or equal to 30 degrees; the curing temperature is in the range of 80-120 degrees C, and the curing time is 3-9 hours, and the higher the temperature, the shorter the curing time.

[0042] The self-roughening super-hydrophobic waterborne matte polyurethane coating can be used in medical protective equipment, medical gauze, wooden furniture, building exterior walls, building guardrails, household textiles, packaging materials and the like to improve the water and dirt repellency and self-cleaning performance.

[0043] It should be noted that the experimental methods used in the present application are conventional methods unless otherwise specified; and the reagents and materials used are commercially available unless otherwise specified.

[0044] Example 1 Preparation of the self-roughening super-hydrophobic waterborne polyurethane matte coating, comprising: 5 g of a non-ionic waterborne polyurethane emulsion with a solid content of 5% and 5 g of a dodecyl guanidine aqueous solution with an alkyl guanidine solid content of 5% are mixed, 0.3 g of a waterborne polydimethylsiloxane emulsion with a mass fraction of 10% is further added, mechanical stirring is performed for 5 min, and ultrasonic stirring is performed for 30 min to obtain a ternary composite system emulsion, wherein the mass percentages of the waterborne polyurethane and the alkyl guanidine in the super-hydrophobic coating are 2.5% and 2.5%, respectively.

[0045] Example 2 Preparation of a self-roughening super-hydrophobic waterborne polyurethane coating on a glass surface, comprising: The original waterborne polyurethane emulsion in Example 1 and the prepared self-roughening super-hydrophobic waterborne polyurethane matte coating are respectively drop-coated on glass, and the drop-coating amounts are controlled to be the same, and curing is performed at 120 degrees C for 3 hours. Figure 1 The infrared spectra of the pure waterborne polyurethane coating and the ternary composite coating are observed, and it is found that compared with the pure waterborne polyurethane coating, the characteristic peaks of C=O and -N-H of the ternary composite coating are obviously shifted, and the intensity is weakened, which proves the occurrence of guanidino-carbonyl hydrogen bond interaction between them. Figure 2 The scanning electron microscope images and water contact angle images of the pure waterborne polyurethane coating and the ternary composite coating on the glass surface are observed, and it is found that the surface of the pure waterborne polyurethane coating is smooth and flat, the water contact angle is 49.3°±0.5°, and the glossiness is 87.6°, which shows high gloss and hydrophilicity; while the surface of the ternary composite system coating presents obvious rough structure, the water contact angle reaches 123.5°±1.3°, and the glossiness is 23.3°, which shows matte hydrophobicity, which proves the formation of self-roughening structure and the hydrophilic-hydrophobic transition of the ternary composite emulsion in the film forming process.

[0046] Example 3 Preparation of self-roughened superhydrophobic waterborne polyurethane coating on cotton fabric surface, comprising: After the self-roughened superhydrophobic waterborne polyurethane matte coating prepared in Example 1 was loaded on the surface of cotton fabric by dip coating and cured at 120 °C for 3 h, it was observed that the self-roughened coating covered the fibers on the surface of the cotton fabric Figure 3 , and the surface gloss was 15.1°, and the water contact angle reached 155.4°±0.8° Figure 4 , showing excellent superhydrophobicity. The droplets of various liquids including water, artificial blood, cola, methylene blue and methyl orange aqueous solution were spherical on the surface of the modified cotton fabric and did not penetrate into the cotton fabric Figure 5 .

[0047] Example 4 Durability of self-roughened superhydrophobic waterborne polyurethane coating on cotton fabric surface The cotton fabric coated in Example 3 was subjected to 140 cycles of abrasion, 140 cycles of adhesive tape peeling, 84 hours of acid solution immersion, 168 hours of water immersion, and 24 hours of ethanol immersion, respectively, and then the surface water contact angle was tested. The results showed that the surface water contact angle of the modified cotton fabric after the above treatments was still greater than 150° Figure 6 , indicating that the self-roughened superhydrophobic waterborne polyurethane coating on the surface of the cotton fabric had excellent mechanical stability and chemical stability.

[0048] Example 5 Preparation of self-roughened superhydrophobic waterborne polyurethane coating on wood surface, comprising: The self-roughened superhydrophobic waterborne polyurethane matte coating prepared in Example 1 was sprayed on the surface of a cedar board, and after curing at 100 °C for 5 h, the water contact angle reached 151.0°±2.7°, showing excellent anti-wetting property, and the surface gloss was 21.1°. Figure 7 After the superhydrophobic waterborne polyurethane coating was applied to the surface of the wood, the anti-wetting property of the aqueous solution on the wood surface was observed, and the aqueous solution was spherical, showing excellent anti-wetting property.

[0049] Example 6 Preparation of self-roughened superhydrophobic waterborne polyurethane coating on gauze surface, comprising: The self-roughened superhydrophobic waterborne polyurethane matte coating prepared in Example 1 was loaded on the surface of gauze by dip coating and cured at 80 °C for 6 h, and the water contact angle reached 153.3°±1.7°, showing not only obvious anti-wetting property to aqueous solution but also excellent liquid repellency to artificial blood. Figure 8The anti-wetting property of the super-hydrophobic water-based polyurethane coating applied on the surface of the gauze to the aqueous solution (left) and artificial blood (right) was observed, and the aqueous solution and artificial blood on the surface of the gauze were spherical, which showed that the super-hydrophobic gauze had excellent anti-wetting property, and also widened the application of the super-hydrophobic gauze in the medical protection field.

[0050] Example 7 The same as example 1, except that the solid content of polyurethane in the used non-ionic water-based polyurethane emulsion was 30%, the solid content of alkyl guanidine in the used aqueous alkyl guanidine solution was 40%, the mass fraction of the added water-based polydimethylsiloxane emulsion was 10%, the mechanical stirring time was 5 min, and the ultrasonic stirring time was 30 min. The mass percentages of the water-based polyurethane and alkyl guanidine in the obtained ternary composite system emulsion were 12% and 16%, respectively. The water contact angle of the self-rough water-based polyurethane coating formed by the solidification of the ternary composite system emulsion prepared in this example on the surface of the gauze could reach 150.5±1.2°.

[0051] Example 8 The same as example 1, except that the used water-based polyurethane was cationic water-based polyurethane, the used alkyl guanidine was polyhexamethylene biguanide, and the used silicone emulsion was acrylic silicone emulsion. As shown in the formula, the water contact angle of the self-rough water-based polyurethane coating formed by the solidification of the ternary composite system emulsion prepared in this example on the surface of the gauze could reach 151.6±0.5°. Figure 9

[0052] The preferred embodiments and their effects are described. However, those skilled in the art can make further changes and modifications to the embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including all the preferred embodiments and all the changes and modifications falling within the scope of the present application.

[0053] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, and the scope of the present application is defined by the appended claims and their equivalents.​

Claims

1. A self-roughening superhydrophobic waterborne polyurethane matte coating, characterized in that, It includes the following components by weight percentage: 1-15% waterborne polyurethane, 0.5-20% alkyl guanidine, 1-9% silicone resin emulsion, and the balance being water.

2. The self-roughening superhydrophobic waterborne polyurethane matte coating according to claim 1, characterized in that, The waterborne polyurethane is either cationic or nonionic.

3. The self-roughening superhydrophobic waterborne polyurethane matte coating according to claim 1, characterized in that, The silicone resin emulsion includes one or more of PDMS emulsion, methylphenyl silicone resin emulsion, epoxy modified silicone resin emulsion, acrylic silicone emulsion, and polyether modified silicone resin emulsion.

4. The self-roughening superhydrophobic waterborne polyurethane matte coating according to claim 1, characterized in that, The alkylguanidine includes one or more of methylguanidine, ethylguanidine, dimethylguanidine, tetramethylguanidine, pentaalkylguanidine, dodecylguanidine, polyhexamethylene biguanide, and polyaminopropyl biguanide.

5. A method for preparing a self-roughening superhydrophobic waterborne polyurethane matte coating according to any one of claims 1 to 4, characterized in that, Includes the following steps: A waterborne polyurethane emulsion and an alkyl guanidine aqueous solution are mixed, and a silicone resin emulsion is added. The mixture is stirred evenly at room temperature and pressure to obtain a rough, superhydrophobic waterborne polyurethane matte coating. The mass percentages of waterborne polyurethane in the waterborne polyurethane emulsion and alkyl guanidine in the alkyl guanidine aqueous solution in the self-roughening superhydrophobic waterborne polyurethane matte coating are 1-15% and 0.5-20%, respectively. The amount of silicone resin emulsion added is 1-9 wt.%.

6. The method for preparing the self-roughening superhydrophobic waterborne polyurethane matte coating according to claim 5, characterized in that, The aqueous polyurethane emulsion contains 2-30 wt.% polyurethane solids; the alkylguanidine aqueous solution contains 1-40 wt.% alkylguanidine solids.

7. The method for preparing the self-roughening superhydrophobic waterborne polyurethane matte coating according to claim 5, characterized in that, The silicone resin emulsion is an emulsion formed by emulsifying organosilicon resin particles with water as the dispersion medium; the organosilicon resin includes one or more of PDMS, methylphenyl silicone resin, epoxy modified silicone resin, acrylic silicone, and polyether modified silicone resin.

8. The application of the self-roughening superhydrophobic waterborne polyurethane matte coating according to any one of claims 1 to 4 in the modification of substrate surface.

9. A coating prepared using the self-roughening superhydrophobic waterborne polyurethane matte coating according to any one of claims 1 to 4, characterized in that, The coating is prepared by applying a self-roughened superhydrophobic waterborne polyurethane matte coating to a rough or smooth substrate by spraying, brushing or dipping, and curing at 80~120℃ for 3~9 hours.

10. The coating prepared by the self-roughening superhydrophobic waterborne polyurethane matte coating according to claim 9, characterized in that, When a coating is applied to a rough substrate, the coating has a water contact angle ≥150° and a gloss ≤30°; when a coating is applied to a smooth substrate, the coating has a water contact angle ≥120° and a gloss ≤30°.

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