Preparation method of hydrophobic coating, prepared hydrophobic coating and application of hydrophobic coating

Abstract

The invention discloses a preparation method of a hydrophobic coating, which comprises the following steps: adding micron-sized biomass powder and alkyl ketene dimer into a cellulose aqueous solution, and uniformly mixing to obtain a mixed emulsion; and adding functional nanoparticles into the mixed emulsion, and uniformly mixing to obtain the hydrophobic coating. The raw materials adopted in the preparation process of the method are degradable biomass materials and non-toxic chemicals, and do not contain fluorine and silicon elements which are not beneficial to environmental protection; the process is simple, only materials are stirred and mixed step by step, special treatment such as high-temperature pressurization is not needed, and any organic solvent is not needed; in addition, any functional particles can be added in the preparation process, so that the functional application of the coating, including sterilization, corrosion resistance and the like, is improved. The invention further discloses the hydrophobic coating prepared through the method and application of the hydrophobic coating.

Description

Technical Field

[0001] The present invention relates to the field of hydrophobic coatings, and more specifically, to a method for preparing a hydrophobic coating, the prepared hydrophobic coating, and applications thereof. Background Art

[0002] Disposable, non-degradable plastic products have caused serious environmental pollution. Paper packaging has become a recognized green and environmentally friendly material and is widely used in packaging a variety of food and industrial products. However, compared to plastic, pure paper-based materials have inferior mechanical properties and are easily damaged by water, losing their original performance and value. Therefore, the development of waterproof, water-resistant, and hydrophobic / hydrophobic paper coatings can compensate for paper's disadvantages in wet strength.

[0003] Currently, the most commonly used paper packaging material in China and abroad is paper lamination, which involves coating the paper surface with a polyethylene film to enhance its mechanical and water resistance. However, since polyethylene film is non-degradable, it remains in the environment after use and disposal, causing serious environmental damage (soil and water). Even if recycled, the film cannot be separated from the paper, making it difficult to recycle and reuse, resulting in significant waste. Silicone and organofluorine coatings are also commonly used to improve paper water resistance. However, these methods are not only expensive, but also pose environmental and health risks due to the presence of organic matter after use and disposal. Per- and polyfluorinated alkyl compounds (PFAS), in particular, have been banned in various countries. Therefore, with the implementation of plastic bans across the globe, there is an urgent need to develop new biodegradable packaging materials and environmentally friendly waterproof coatings that are free of silicone and fluorine-based organic water repellents and offer strength and water resistance comparable to plastics, to replace non-degradable, single-use plastic packaging materials.

[0004] Compared to organic solvents, water, as an environmentally friendly and sustainable alternative, is gaining increasing attention in the preparation of hydrophobic coatings. For example, SiO2 nanoparticles are modified with MPTMS-PSS-PFDT, and a coating is prepared by spraying an aqueous dispersion of the modified SiO2 with a polysiloxane emulsion. SiO2 nanoparticles are modified with hydrophobic and hydrophilic polymers, and an aqueous dispersion is obtained by adjusting the content ratio of the two polymers. This modified SiO2 aqueous dispersion is then sprayed with a styrene-acrylic copolymer emulsion to prepare a coating (constructing a water-based hydrophobic coating with controllable water droplet adhesion). Although amphiphilic-modified nanoparticles can be dispersed in water, the modification process is complex and involves organic solvents. Another effective method for preparing hydrophobic coatings via aqueous dispersion is to disperse the hydrophobic nanoparticles in water using a dispersant. For example, cellulose nanofibers (CNFs) are used as dispersants to prepare water-based hydrophobic coatings without the use of any organic solvents. However, limitations in the preparation process and compatibility issues with some particles limit their use.

[0005] In general, the preparation of hydrophobic surfaces mainly involves using nanomaterials such as carbon, metal or metal oxides to jointly construct the rough surface of the hydrophobic coating, and then performing low surface energy modification. However, these preparation methods are usually cumbersome and require the use of large amounts of toxic organic solvents, fluorine-containing and silicon-containing substances, which are harmful to the human body and the environment. In addition, metal nanomaterials themselves are also toxic and structurally unstable, and carbon materials often exhibit poor solution processability due to the lack of surface functional groups. When they are compounded with a polymer matrix, they will cause agglomeration due to weak interfacial interactions, which is not conducive to the stability of the coating. In addition, the general hydrophobic coating and functional particle blending structure is easily destroyed, and multifunctional usage scenarios cannot be achieved. Summary of the Invention

[0006] Based on the above problems, the present invention aims to provide a method for preparing a hydrophobic coating, a prepared hydrophobic coating and its application. The preparation process of the hydrophobic coating has the advantages of being green and low-cost, and solves the problem of environmental pollution of hydrophobic coatings; At the same time, without using fluorine-containing and silicon-containing substances, the hydrophobic properties of the coating are achieved.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In one aspect, the present invention provides a method for preparing a hydrophobic coating, the method comprising the following steps:

[0009] adding micron-sized biomass powder and alkyl ketene dimer (AKD) into a cellulose aqueous solution and mixing them to obtain a mixed emulsion;

[0010] Functional nanoparticles are added to the mixed emulsion and mixed to obtain the hydrophobic coating.

[0011] Inspired by the surface structure of Cassiae leaves and Bauhinia leaves in nature, the present invention provides a green and environmentally friendly hydrophobic coating with a simple process, aqueous synthesis, and load-bearing functional nanoparticles (including but not limited to TiO2, ZnO, Al2O3, etc. and various metal particles). It was unexpectedly found in the present invention that in the preparation method, after using AKD, combined with micro-nanoscale biomass powder and cellulose aqueous solution, the hydrophobic coating prepared has a biomimetic effect, which is an effect that cannot be achieved by using substances such as silicon and fluorine. In the preparation process of the hydrophobic coating, the raw materials are all biodegradable and non-toxic materials, and are carried out in an aqueous environment without the use of any toxic organic solvents and inorganic nanoparticles and silicon and fluorine substances. The hydrophobic coating prepared by the hydrophobic coating is referred to as CNF / NCP coating. In addition, the biggest advantage of the hydrophobic coating is loadability. During the coating preparation process, functional nanoparticles can be added according to the needs of actual applications to achieve various functional requirements. After adding functional nanoparticles, the coating obtained is still hydrophobic and stable. Taking the loaded TiO2 nanoparticles as an example, the TiO2@CNF / NC coating can realize the waterproof and hydrophobic, self-cleaning, sterilization, and anti-corrosion functions of the solid surface, and can be used for fruit, vegetable, and food packaging.

[0012] Furthermore, the mixing to obtain the mixed emulsion comprises the following steps: heating to dissolve AKD, and then stirring.

[0013] Furthermore, the biomass powder is selected from one or more of corn cobs, reed straw, bamboo powder, wood powder and wheat straw. In the technical solution of the present invention, the particle size of the biomass powder can be in the micron level, and the specific size is not required.

[0014] In the technical solution of the present invention, there is no requirement for the selection of cellulose in the cellulose aqueous solution.

[0015] Furthermore, the mass ratio of the biomass powder, AKD and cellulose is 1:(0.3-5):(0.03-2).

[0016] Furthermore, the mass ratio of the biomass powder, AKD and cellulose is 1:(0.6-5):(0.05-1.5). At this time, the hydrophobic coating prepared by this method has excellent superhydrophobicity.

[0017] Furthermore, the functional nanoparticles are selected from one or more of titanium dioxide, zinc oxide, aluminum hydroxide, graphene, boron nitride, magnesium oxide and aluminum oxide. In the technical solution of the present invention, the particle size of the functional nanoparticles can be nanometer-scale.

[0018] Furthermore, the mass ratio of the biomass powder to the functional nanoparticles is 1:(0.05-1.5).

[0019] Furthermore, no organic solvent is added during the preparation process.

[0020] Furthermore, in the preparation process, no silicon-containing and / or fluorine-containing substances are used.

[0021] In the preparation method of the present invention, an aqueous phase is used instead of an organic solvent phase in the preparation process; silicon-containing and fluorine-containing substances are not used to achieve a hydrophobic surface; a regular biomimetic rough surface replaces an irregular rough surface to enhance the stability and controllability of the hydrophobic structure; and functional particles can be introduced during the preparation process of the coating to achieve multifunctionality.

[0022] In another aspect, the present invention provides a hydrophobic coating prepared by the preparation method described above.

[0023] In another aspect, the present invention provides a hydrophobic coating, which is obtained by coating the hydrophobic coating prepared by the preparation method described above or the hydrophobic coating described above on the surface of a substrate and drying it.

[0024] Furthermore, the substrate is selected from one of paper, wood, cotton, linen and chemical fiber fabrics, glass, polymer materials, metal materials, bricks and concrete.

[0025] In another aspect, the present invention provides use of the hydrophobic coating as described above in the fields of photocatalysis, waterproofing and hydrophobicity, antibacterial, flame retardancy, self-cleaning or food preservation.

[0026] The beneficial effects of the present invention are as follows:

[0027] The hydrophobic coating prepared from the hydrophobic coating provided by the present invention has excellent hydrophobicity and can realize the self-cleaning function; the hydrophobic coating has the advantages of being green and low-cost; the preparation method is simple in process, and only requires step-by-step stirring and mixing of materials, without the need for special treatment such as high temperature and pressurization, and without the need to use any organic solvents; and any functionalized particles can be added during the preparation process to increase the functional applications of the coating, including sterilization, anti-corrosion and other properties; the raw materials used in the preparation method are all degradable biomass materials and non-toxic chemicals, and do not contain fluorine-containing substances and inorganic nanoparticles that are not conducive to the environment; the solvent used is water, and there is no need for cumbersome wastewater treatment links; no waste is generated during the entire preparation process, solving the problem of environmental pollution of existing hydrophobic coatings.

[0028] The hydrophobic coating prepared by the preparation method of the present invention uses AKD for papermaking as the oil phase to form a water-in-oil Pickering emulsion, provides hydrophobicity and a bionic petal-shaped micro-nano rough surface, achieves hydrophobicity, has a bionic effect, does not use fluorine-containing and silicon-containing substances, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Figure 1 The water contact angle of the coating prepared in Example 1 is shown.

[0031] Figure 2 The microstructure of the coating surface prepared in Example 1 is shown.

[0032] Figure 3 Antibacterial test results are shown: a) blank E. coli culture test, b) E. coli culture test from Example 1; c) blank Steroids aureus culture test, d) Steroids aureus culture test from Example 1. "Dark" and "UV light" refer to experiments conducted in the dark and under UV light, respectively. DETAILED DESCRIPTION

[0033] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0034] Example 1

[0035] A method for preparing a super-hydrophobic coating comprises the following steps:

[0036] Take 10g of micro-nano-scale corn cobs and 7.5g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 0.5%, heat it to 60℃ and stir at high speed to fully dissolve and mix it evenly; then add 1g of TiO2 nanoparticles to the above emulsion and continue stirring for a period of time until it is fully dispersed to obtain a functional mixed emulsion, that is, a superhydrophobic coating.

[0037] A method for preparing a super-hydrophobic coating comprises the following steps:

[0038] The prepared functional mixed emulsion is evenly sprayed on the surface of the paper substrate, and a coating is obtained after drying.

[0039] like Figure 1 As shown in FIG, the water contact angle test result of the coating is 161°.

[0040] The microstructure of the coating surface was observed, such as Figure 2 As shown in the figure, its microstructure (such as Figure 2 (shown in b) and the surface microstructure of Cassia seed (the macroscopic morphology of Cassia seed is shown in Figure 2 As shown on the leftmost side of the figure, the microscopic morphology is as follows Figure 2 Similar to that shown in (a).

[0041] The functional coating was tested for antibacterial activity against Escherichia coli and Staphylococcus aureus. Figure 3 As shown. Among them, Figure 3 In the figure, a represents a blank sample culture experiment with E. coli, b represents a sample culture experiment with the coating of this example, c represents a blank sample culture experiment with Steroides aureus, and d represents a sample culture experiment with Steroides aureus. The results show that bacteria grow rapidly on the unsprayed surface, while no obvious bacterial colonies are observed on the surface after spraying the sample of this example, indicating its good antibacterial properties. These results demonstrate that the sample of this example can be used for hydrophobicity, antibacterial properties, and food preservation.

[0042] Example 2

[0043] A method for preparing a hydrophobic coating comprises the following steps:

[0044] Take 15g of micro-nanoscale reed straw and 5g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 1%, heat it to 80℃ and stir at high speed to fully dissolve it and mix it evenly; then add 1g of zinc oxide nanoparticles to the above emulsion and continue stirring for a period of time until it is fully dispersed to obtain a mixed emulsion, which is also a hydrophobic coating.

[0045] A method for preparing a hydrophobic coating comprises the following steps:

[0046] The prepared mixed emulsion was evenly sprayed on the surface of a glass substrate. After drying, the water contact angle of the coating obtained was 135°, and the coating had an antibacterial property similar to that of Example 1.

[0047] Example 3

[0048] A method for preparing a super-hydrophobic coating comprises the following steps:

[0049] Take 2.5g of micro-nanoscale bamboo powder and 10g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 1.5%, heat it to 90°C and stir it at high speed to fully dissolve it and mix it evenly; then add 2.5g of aluminum hydroxide nanoparticles to the above emulsion and continue stirring for a period of time until it is fully dispersed to obtain a mixed emulsion, which is also a superhydrophobic coating.

[0050] A method for preparing a super-hydrophobic coating comprises the following steps:

[0051] The prepared mixed emulsion is evenly sprayed on the surface of a polypropylene substrate. After drying, the obtained coating has a water contact angle of 165° and is a flame retardant waterproof coating.

[0052] Example 4

[0053] A method for preparing a hydrophobic coating comprises the following steps:

[0054] Take 5g of micro-nanoscale wood powder and 2.5g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 0.1%, heat it to 55°C and stir it at high speed to fully dissolve and mix it evenly; then add 0.25g of graphene to the above emulsion and continue stirring for a while until it is fully dispersed to obtain a functional mixed emulsion, that is, a hydrophobic coating.

[0055] A method for preparing a hydrophobic coating comprises the following steps:

[0056] The prepared functional mixed emulsion is evenly sprayed on the surface of a wood substrate. After drying, the water contact angle of the coating obtained is 133°, and the coating has anti-corrosion properties.

[0057] Example 5

[0058] A method for preparing a super-hydrophobic coating comprises the following steps:

[0059] Take 7.5g of micro-nanoscale wood powder and 8g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 0.5%, heat it to 70°C and stir at high speed to fully dissolve and mix it evenly; then add 1.25g of nano-boron nitride to the above solution containing micro-nanoscale wood powder, nanocellulose and AKD, and continue stirring for a period of time until it is fully dispersed to obtain a mixed emulsion, that is, a superhydrophobic coating.

[0060] A method for preparing a super-hydrophobic coating comprises the following steps:

[0061] The prepared mixed emulsion is evenly sprayed on the surface of a non-woven fabric substrate. After drying, the water contact angle of the coating obtained is 156°, and the coating has anti-corrosion performance.

[0062] Example 6

[0063] A method for preparing a super-hydrophobic coating comprises the following steps:

[0064] Take 5g of micro-nano-scale corn cobs and 6g of AKD and add them to 250g of nanocellulose with a solid content of 0.2%, heat it to 75°C and stir at high speed to fully dissolve and mix it evenly; then add 1g of nano-magnesium oxide and 1.5g of nano-aluminum oxide to the above emulsion and continue stirring for a period of time until it is fully dispersed to obtain a mixed emulsion, which is also a super-hydrophobic coating.

[0065] A method for preparing a super-hydrophobic coating comprises the following steps:

[0066] The prepared functional mixed emulsion is evenly sprayed on the surface of a kraft paper substrate. After drying, the water contact angle of the obtained coating is 152°, and the coating has flame retardant properties.

[0067] Example 7

[0068] A method for preparing a hydrophobic coating comprises the following steps:

[0069] Take 10g of micro-nanoscale corn cobs and 8g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 0.4%, heat it to 65°C and stir at high speed to fully dissolve and mix it evenly; then add 0.25g of graphene and 0.5g of boron nitride to the above solution containing corn cob powder, nanocellulose and AKD, and continue stirring for a period of time until it is fully dispersed to obtain a mixed emulsion, which is also a hydrophobic coating.

[0070] A method for preparing a hydrophobic coating comprises the following steps:

[0071] The prepared functional mixed emulsion is evenly sprayed on the surface of a concrete substrate. After drying, the water contact angle of the coating obtained is 151°, and the coating has anti-corrosion properties.

[0072] Example 8

[0073] A method for preparing a hydrophobic coating comprises the following steps:

[0074] Take 8g of micro-nano bamboo powder and 4g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 0.25%, heat it to 65°C and stir it at high speed to fully dissolve and mix it evenly; then add 1g of nano titanium dioxide and 0.25g of graphene to the above emulsion and continue stirring for a period of time until it is fully dispersed to obtain a mixed emulsion, which is also a hydrophobic coating.

[0075] A method for preparing a hydrophobic coating comprises the following steps:

[0076] The prepared functional mixed emulsion is evenly sprayed on the surface of the wood substrate. After drying, the water contact angle of the coating obtained is 142°, and the coating has both antibacterial and anti-corrosion properties.

[0077] Example 9

[0078] A method for preparing a super-hydrophobic coating comprises the following steps:

[0079] Take 8g of micro-nanoscale wheat straw and 7.5g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 0.75%, heat it to 60°C and stir at high speed to fully dissolve and mix it evenly; then add 1g of nano-titanium dioxide and 1.5g of nano-magnesium oxide to the above emulsion and continue stirring for a period of time until it is fully dispersed to obtain a mixed emulsion, which is also a super-hydrophobic coating.

[0080] A method for preparing a super-hydrophobic coating comprises the following steps:

[0081] The prepared functional mixed emulsion is evenly sprayed on the surface of a kraft paper substrate. After drying, the water contact angle of the obtained coating is 163°, and the coating has both antibacterial and flame retardant properties.

[0082] Example 10

[0083] A method for preparing a super-hydrophobic coating comprises the following steps:

[0084] Take 12.5g of micro-nanoscale bamboo powder and 8g of AKD and add them to 250g of nanocellulose aqueous solution with a solid content of 0.25%, heat it to 65°C and stir at high speed to fully dissolve and mix it evenly; then add 0.25g of graphene and 1.25g of halloysite to the above emulsion and continue stirring for a while until it is fully dispersed to obtain a mixed emulsion, which is also a superhydrophobic coating.

[0085] A method for preparing a super-hydrophobic coating comprises the following steps:

[0086] The prepared functional mixed emulsion is evenly sprayed on the surface of a cotton cloth substrate. After drying, the water contact angle of the obtained coating is 158° and the coating has both anti-corrosion and flame retardant properties.

[0087] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrophobic coating, characterized in that, The steps include: adding micron-sized biomass powder and alkyl ketene dimer to a cellulose aqueous solution and mixing them to obtain a mixed emulsion; Functional nanoparticles are added to the mixed emulsion and mixed to obtain the hydrophobic coating.

2. The preparation method according to claim 1, characterized in that The biomass powder is selected from one or more of corn cobs, reed straw, bamboo powder, wood powder and wheat straw.

3. The preparation method according to claim 1, characterized in that The mass ratio of the biomass powder, AKD and cellulose is 1:(0.3-5):(0.03-2).

4. The preparation method according to claim 1, characterized in that The functional nanoparticles are selected from one or more of titanium dioxide, zinc oxide, aluminum hydroxide, graphene, boron nitride, magnesium oxide and aluminum oxide.

5. The preparation method according to claim 1, characterized in that During the preparation process, no organic solvent was added.

6. The preparation method according to claim 1, characterized in that During the preparation process, no silicon-containing and / or fluorine-containing substances are used.

7. The hydrophobic coating prepared by the preparation method according to any one of claims 1 to 6.

8. A hydrophobic coating, characterized in that The hydrophobic coating prepared by the preparation method according to any one of claims 1 to 6 or the hydrophobic coating according to claim 7 is coated on the surface of a substrate and dried to obtain the hydrophobic coating.

9. The hydrophobic coating according to claim 8, characterized in that The substrate is selected from one of paper, wood, cotton, linen, chemical fiber fabric, glass, polymer material, metal material, brick and concrete.

10. Use of the hydrophobic coating according to any one of claims 8 to 9 in the fields of photocatalysis, waterproofing and hydrophobicity, antibacterial, flame retardancy, self-cleaning or food preservation.

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