Fluorine-free overall super-hydrophobic coating material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of super-hydrophobic materials, and particularly relates to a fluoride-free overall super-hydrophobic coating material and a preparation method and application thereof.The fluoride-free porous overall super-hydrophobic coating prepared through a non-solvent phase separation technology has low surface energy, high abrasion resistance and overall super-hydrophobicity, and a micro-rough structure of the fluoride-free overall super-hydrophobic coating exists on the surface of the coating and also exists on the surface of the coating. The interior of the material is of a microporous structure; after the coating is worn, the exposed new surface also has a micro-coarse structure, so that the coating has good super-hydrophobic mechanical stability, the problem of durability of the super-hydrophobic coating in an abrasion environment is solved, and the super-hydrophobic coating is suitable for various fields such as special engineering structure protection, metal mechanical corrosion prevention and oil-water separation.

Description

Technical Field

[0001] The present invention belongs to the technical field of super-hydrophobic materials, and in particular relates to a fluorine-free overall super-hydrophobic coating material and a preparation method and application thereof. Background Art

[0002] Superhydrophobic materials have very broad application prospects in many fields such as building protection, metal corrosion protection, waterproof, dustproof and anti-fouling of fiber fabrics, oil-water separation, pipeline transportation, etc. Taking building protection as an example, superhydrophobic coatings can effectively prevent water-soluble harmful ions from eroding the interior of the engineering structure, and can also ensure the cleanliness and pollution-freeness of the surface of the engineering structure to a certain extent. Coastal docks, offshore wind turbines and other marine structures are in high humidity and high salt pollution service environment all year round, and superhydrophobic coatings are even more needed to protect them.

[0003] Superhydrophobicity refers to the contact angle and rolling angle between the surface of the material and water being greater than 150° and less than 10° respectively. The superhydrophobicity of the material mainly comes from two characteristics: one is the low surface energy of the material, and the other is that the surface of the material has a rough structure at the micrometer or nanometer level. According to the Cassie-Baxter theory, the above two characteristics can not only reduce the solid-liquid interface force, but also help to capture and store gas on the surface of the material, thereby further reducing the attraction between the solid and the liquid. The realization of low surface energy of materials often requires the introduction of low surface energy functional groups such as fluorine atoms, long alkane chains, and benzene rings. There are many methods for constructing the rough structure of materials, including immersion, spraying, chemical vapor deposition, template method, chemical etching, plasma etching, electrospinning and electrodeposition.

[0004] At present, scholars also mostly start from the above two points to improve the super-hydrophobic effect of coating.For example, patent CN116769344B discloses a fluorinated graphene / SiO2 / fluorosilane composite material and preparation method thereof, mainly by introducing SiO2 of loaded fluorinated graphene in resin coating, to reduce the surface energy of resin material.The coating can play the effects of long-term antifouling, self-cleaning on the surface of different types of insulating substrates.Patent CN118325467B discloses a super-hydrophobic silicone rubber coating preparation method, which uses the low surface energy characteristics of silicone rubber in combination with solvent phase separation to prepare a super-hydrophobic coating with micro-rough structure.The contact angle of the coating with water is greater than 150 °, and the rolling angle is less than 8 °, which has important application prospects in the fields of waterproofing, anti-pollution, and anti-icing.

[0005] However, existing super-hydrophobic coatings generally have defects such as large amount of fluoride used and poor mechanical stability. Especially in terms of mechanical stability, existing super-hydrophobic coating materials and preparation processes are difficult to achieve stable protection in long-term abrasive environments, such as offshore service environments. Summary of the invention

[0006] The object of the present invention is to provide a fluorine-free overall super-hydrophobic coating material and its preparation method and application. The overall super-hydrophobic coating material, fluorine-free and with strong mechanical stability, compared with traditional super-hydrophobic coatings, has the greatest advantage that micro-rough structures are not only present on the coating surface, but also have a multi-microporous structure inside the material. Therefore, there is also a micro-rough structure in the new surface exposed after the coating is worn, which makes the coating have good super-hydrophobic mechanical stability, and solves the durability problem of super-hydrophobic coatings in abrasive environments.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] In the first aspect, the present invention provides a fluorine-free integral super-hydrophobic coating material, comprising an epoxy resin bonding layer and a super-hydrophobic polydimethylsiloxane surface layer loaded on the surface thereof; the epoxy resin bonding layer is composed of an epoxy resin main agent, an epoxy resin curing agent and acetone; the super-hydrophobic polydimethylsiloxane surface layer is composed of a PDMS main agent, a PDMS curing agent, polyethylene powder and an aqueous phase solvent.

[0009] In some other embodiments, the epoxy resin main agent is one or more of bisphenol A epoxy resin E12, E20, E44, E51, bisphenol F epoxy resin NPEF-170, NPEF-187 or 4,5-epoxytetrahydrophthalic acid diglycidyl ester;

[0010] Or, the epoxy resin curing agent is one or more of polyetheramine curing agent D230, T403, D400, D2000, FL1000, polyamide curing agent 650, 651, T31 modified amine curing agent, ethylenediamine curing agent or xylenediamine curing agent.

[0011] In some other embodiments, the mass ratio of the epoxy resin main agent to the epoxy resin curing agent is (2.5-3.5):1; the mass ratio of the epoxy resin main agent to acetone is (1-1.8):1.

[0012] In some other embodiments, the PDMS main agent and the PDMS curing agent are one or more of Dow Corning SYLGARD 184 and its supporting curing agent, Dow Corning SYLGARD 182 and its supporting curing agent, or Momentive RTV615 and its supporting curing agent;

[0013] Or, the aqueous phase solvent is a solvent composed of ethanol and water;

[0014] Alternatively, the particle size of the polyethylene powder is 5 to 7 μm, and the number average molecular weight of the polyethylene powder is 50,000 to 80,000.

[0015] In some other embodiments, the mass ratio of the PDMS main agent to the PDMS curing agent is 10:(0.8-1.5); the mass ratio of the polyethylene powder to the PDMS main agent is (1-3):5; the mass ratio of the ethanol to water is (0.15-0.25):1; the mass ratio of the PDMS main agent to the aqueous phase solvent is 1:(0.6-1.2).

[0016] In a second aspect, the present invention provides a method for preparing the fluorine-free overall super-hydrophobic coating material according to the first aspect, comprising the following steps:

[0017] (1) mixing polyethylene powder, PDMS main agent, and PDMS curing agent to prepare mixed powder, and then dropping an aqueous phase solvent formed by mixing water and ethanol into the mixed powder to prepare a water-in-oil silicone oil emulsion;

[0018] (2) mixing acetone, an epoxy resin main agent, and an epoxy curing agent to prepare an epoxy resin adhesive; spraying the epoxy resin adhesive on the surface of the substrate, and then pre-curing to form an epoxy resin adhesive layer;

[0019] (3) applying a water-in-oil silicone oil emulsion on the surface of the epoxy resin bonding layer, and forming a super-hydrophobic polydimethylsiloxane surface layer after vacuum defoaming, curing and drying; and polishing the super-hydrophobic polydimethylsiloxane surface layer to form a fluorine-free overall super-hydrophobic coating material.

[0020] In some other embodiments, in step (2), the compressed air pressure used for spraying is 0.15-0.35 MPa, the diameter of the spray pen is 0.3 mm, and the distance between the nozzle and the substrate is 4-6 cm;

[0021] Alternatively, the pre-curing is: curing at 20-28° C. for 6-10 hours.

[0022] In some other embodiments, in step (3), the vacuum defoaming is: defoaming for 10 to 20 minutes at room temperature under an air pressure of -0.09 to -0.05 MPa;

[0023] Or, the curing is: curing at 55-70° C. for 4-8 hours;

[0024] Or, the drying is: drying at 100-115° C. for 12-24 hours.

[0025] In some other embodiments, in step (3), the polishing is performed using 300-1000 mesh sandpaper at a pressure of 15-25 kPa;

[0026] Alternatively, the thickness of the fluorine-free overall super-hydrophobic coating material is 0.5 to 2 mm.

[0027] In a third aspect, the present invention provides an application of the fluorine-free integral super-hydrophobic coating material described in the first aspect in special engineering structure protection, metal machinery corrosion protection or oil-water separation.

[0028] Beneficial effects of the present invention:

[0029] (1) The fluorine-free overall super-hydrophobic coating material prepared by the present invention has the advantages of overall super-hydrophobicity, high wear resistance, and no fluorine. Its water contact angle is greater than 153° and the rolling angle is less than 7.8°. After polishing with sandpaper, the contact angle of the fluorine-free overall super-hydrophobic coating material is still greater than 150°, and the super-hydrophobicity does not decline.

[0030] (2) The present invention utilizes the property that oil and water are immiscible and adopts a simple mechanical stirring process to prepare an oil-in-water silicone oil emulsion. The oil-in-water silicone oil emulsion is composed of a PDMS main agent, a curing agent, polyethylene powder and an ethanol / water solvent. The surface energy of PDMS and polyethylene themselves is very low. After mixing with the ethanol / water solvent and stirring, the water phase microbubbles can be evenly distributed inside the oil phase to form an oil-in-water silicone oil emulsion; and the density of the polyethylene powder and the ethanol / water solution is very close to that of PDMS, which is the key to ensuring the uniform distribution of various substances inside the emulsion. The emulsion can be prepared only by a simple physical process, and it does not contain fluoride, has a uniform texture, and is relatively stable, which is convenient for subsequent coating and use.

[0031] (3) In the present invention, the epoxy resin binder is first sprayed on the surface of the substrate, and then pre-cured for a period of time before the water-in-oil silicone oil emulsion is applied. The abundant hydroxyl groups in the epoxy resin can undergo hydrolysis and condensation reactions with the siloxane groups in the PDMS, ensuring that the cured super-hydrophobic silicone layer can adhere firmly.

[0032] (4) The present invention creatively adopts a non-solvent phase separation process to obtain a fluorine-free porous overall super-hydrophobic coating; the cured super-hydrophobic coating has low surface energy (PDMS and polyethylene have low surface energy), high wear resistance (polyethylene improves hardness) and overall super-hydrophobicity (uniformly distributed micropores inside provide a micro-rough structure for the new interface that appears after abrasion); especially after being severely worn, the coating still has a stable super-hydrophobic effect. It has excellent application effects in many fields such as special engineering structure protection, metal machinery anti-corrosion and oil-water separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0034] Figure 1The present invention is a schematic diagram of a process for preparing a fluorine-free integral super-hydrophobic coating material by using a non-solvent phase separation process in an embodiment of the present invention; wherein, (1) spraying, (2) pre-curing, (3) stirring, (4) dripping an aqueous phase, (5) applying an oil-in-water silicone oil emulsion, (6) curing, (7) phase separation, and (8) surface polishing; ① substrate, ② epoxy resin adhesive, ③ pre-cured epoxy adhesive layer, ④ polyethylene powder, ⑤ PDMS main agent and curing agent, ⑥ ethanol / water solvent (aqueous phase), ⑦ oil phase, ⑧ oil-in-water silicone oil emulsion, ⑨ cured oil-in-water composite PDMS, ⑩ porous PDMS;

[0035] Figure 2 This is a diagram of the internal micropore structure of the fluorine-free overall super-hydrophobic coating material in an embodiment of the present invention; wherein, the circular marks are polyethylene micro-nanoparticles, and the square marks are the pore structures in PDMS. DETAILED DESCRIPTION

[0036] The present invention provides a fluorine-free overall super-hydrophobic coating material and a preparation method thereof, and its process schematic diagram is as follows Figure 1 As shown, (1) spraying, (2) pre-curing, (3) stirring, (4) dripping water phase, (5) coating oil-in-water silicone oil emulsion, (6) curing, (7) phase separation, (8) surface polishing; ① substrate, ② epoxy resin adhesive, ③ pre-cured epoxy adhesive layer, ④ polyethylene powder, ⑤ PDMS main agent and curing agent, ⑥ ethanol / water solvent (water phase), ⑦ oil phase, ⑧ oil-in-water silicone oil emulsion, ⑨ cured oil-in-water composite PDMS, ⑩ porous PDMS. Specifically includes the following steps:

[0037] Step 1: Mix the PDMS main agent and the matching curing agent in proportion, and stir mechanically at room temperature at a speed of 500 rpm for 5 minutes; add polyethylene micro-nano powder, and stir mechanically at room temperature at a speed of 700-1200 rpm for 10-20 minutes to obtain a silicone oil phase; prepare an aqueous phase solvent composed of ethanol and water in proportion, and slowly add it to the oil phase at a drop rate of 30-40 mL / hr. During this process, stir continuously at a speed of 600-1000 rpm. After the addition is completed, continue stirring at room temperature for 30 minutes to obtain a uniform oil-in-water silicone oil emulsion.

[0038] Step 2: Mix acetone and water-based epoxy resin, stir evenly; then add epoxy curing agent, continue to stir evenly, and obtain coating adhesive. After spraying the coating adhesive evenly on the surface of the substrate, it needs to be pre-cured for 8 hours.

[0039] Step 3: After the oil-in-water silicone oil emulsion is evenly applied on the surface of the bonding layer, it is subjected to vacuum defoaming treatment at room temperature; after the defoaming is completed, it is cured at 55-70°C, and then the internal water phase is dried at 100-115°C to obtain porous PDMS; finally, the cured coating surface is slightly polished with 300-1000 mesh sandpaper to obtain SHC-PDMS.

[0040] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0041] The present invention has no particular limitation on the source of the reagents, and commercially available products known to those skilled in the art may be used.

[0042] Example 1

[0043] A method for preparing a fluorine-free overall super-hydrophobic coating material comprises the following steps:

[0044] Step 1: Mix 10 parts of Dow Corning SYLGARD 184 main agent and 1 part of the matching curing agent, and stir mechanically at room temperature for 5 minutes at a speed of 500 rpm; add 6 parts of polyethylene powder (particle size is 6.5μm, number average molecular weight is 60,000), and stir mechanically at room temperature for 10 minutes at a speed of 1000 rpm to obtain a silicone oil phase; 1.4 parts of ethanol and 8.6 parts of deionized water are mixed evenly to form an aqueous phase solvent, and slowly added to the oil phase at a drip rate of 30mL / hr. During this process, stirring is continued at a speed of 700rpm. After the addition is completed, stirring is continued at room temperature for 30 minutes to obtain a uniform oil-in-water silicone oil emulsion.

[0045] Step 2: Mix 5 parts of acetone and 5 parts of water-based epoxy resin main agent (bisphenol A epoxy resin E12) and stir evenly; then add 1.7 parts of D230 curing agent and continue to stir evenly to obtain a coating adhesive. Spray the coating adhesive evenly (the compressed air pressure used for spraying is 0.2MPa, the diameter of the spray pen is 0.3mm, and the distance between the nozzle and the substrate is 5cm) on the surface of the substrate and pre-cure it at room temperature for 8 hours.

[0046] Step 3: After the water-in-oil silicone oil emulsion is evenly applied on the surface of the bonding layer, a vacuum defoaming treatment is performed at room temperature (defoaming for 10 minutes at an air pressure of -0.05 MPa); after the defoaming is completed, it is cured at 60°C for 4 hours, and then dried at 105°C for 24 hours to obtain a porous PDMS coating; finally, the cured coating surface is slightly polished with 800-mesh sandpaper to obtain SHC-PDMS.

[0047] Figure 2 The internal microporous structure of the fluorine-free overall super-hydrophobic coating material in Example 1 of the present invention; wherein the circular marks are polyethylene micro-nanoparticles, and the square marks are the pore structures in PDMS. Figure 2It can be seen that the micro-roughness of the coating material exists not only on the surface of the coating, but also in the microporous structure inside the material. Therefore, the new surface exposed after the coating is worn also has a micro-roughness, which makes the coating have good super-hydrophobic mechanical stability and solves the durability problem of super-hydrophobic coating in abrasive environment.

[0048] Example 2

[0049] A method for preparing a fluorine-free overall super-hydrophobic coating material comprises the following steps:

[0050] Step 1: Mix 10 parts of Dow Corning SYLGARD 182 main agent and 1 part of matching curing agent, and stir mechanically at room temperature for 5 minutes at a speed of 500 rpm; add 4 parts of polyethylene powder (particle size of 5 μm, number average molecular weight of 80,000), and stir mechanically at room temperature for 10 minutes at a speed of 1000 rpm to obtain a silicone oil phase; mix 1.3 parts of ethanol and 6.7 parts of deionized water to form an aqueous phase, and slowly add it to the oil phase at a drop rate of 30 mL / hr. During this process, stir continuously at a speed of 700 rpm. After the addition is completed, continue stirring at room temperature for 30 minutes to obtain a uniform oil-in-water silicone oil emulsion.

[0051] Step 2: Mix 5 parts of acetone diluent and 8 parts of water-based epoxy resin main agent (bisphenol F epoxy resin NPEF-170) and stir evenly; then add 3 parts of T31 curing agent and continue to stir evenly to obtain a coating adhesive. Spray the coating adhesive evenly (the compressed air pressure used for spraying is 0.2MPa, the diameter of the spray pen is 0.3mm, and the distance between the nozzle and the substrate is 4cm) on the surface of the substrate and pre-cure it at room temperature for 8 hours.

[0052] Step 3: After the water-in-oil silicone oil emulsion is evenly applied on the surface of the bonding layer, a vacuum defoaming treatment is performed at room temperature (defoaming for 15 minutes at an air pressure of -0.09 MPa); after the defoaming is completed, it is cured at 60°C for 8 hours, and then dried at 105°C for 24 hours to obtain a porous PDMS coating; finally, the cured coating surface is slightly polished with 800-mesh sandpaper to obtain SHC-PDMS.

[0053] Example 3

[0054] A method for preparing a fluorine-free overall super-hydrophobic coating material comprises the following steps:

[0055] Step 1: Mix 10 parts of Dow Corning SYLGARD 184 main agent and 1 part of curing agent, and stir mechanically at room temperature for 5 minutes at a speed of 500 rpm; add 6 parts of polyethylene powder (particle size is 7μm, number average molecular weight is 70,000), and stir mechanically at room temperature for 10 minutes at a speed of 1000 rpm to obtain a silicone oil phase; mix 1.7 parts of ethanol and 10.3 parts of deionized water to form an aqueous phase, and slowly add it to the oil phase at a drop rate of 30mL / hr. During this process, stir continuously at a speed of 700 rpm. After the addition is completed, continue stirring at room temperature for 30 minutes to obtain a uniform oil-in-water silicone oil emulsion.

[0056] Step 2: Mix 5 parts of acetone diluent and 6 parts of water-based epoxy resin main agent (4,5-epoxytetrahydrophthalic acid diglycidyl ester) and stir evenly; then add 2 parts of polyamide 650 curing agent and continue to stir evenly to obtain a coating adhesive. Spray the coating adhesive evenly (the compressed air pressure used for spraying is 0.3MPa, the diameter of the spray pen is 0.3mm, and the distance between the nozzle and the substrate is 5cm) on the surface of the substrate and pre-cure for 8 hours.

[0057] Step 3: After the water-in-oil silicone oil emulsion is evenly applied on the surface of the bonding layer, a vacuum defoaming treatment is performed at room temperature (defoaming for 12 minutes at an air pressure of -0.07 MPa); after the defoaming is completed, it is cured at 60°C for 4 hours, and then dried at 105°C for 24 hours to obtain a porous PDMS coating; finally, the cured coating surface is slightly polished with 800-mesh sandpaper to obtain SHC-PDMS.

[0058] Comparative Example 1

[0059] The difference from Example 1 is that no polyethylene powder is added, and the other preparation methods are exactly the same as those of Example 1.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that the aqueous phase is prepared by mixing 0.6 parts of ethanol and 3.4 parts of deionized water. The other preparation methods are exactly the same as those in Example 1.

[0062] Comparative Example 3

[0063] The difference from Example 1 is that the aqueous phase is prepared by mixing 1.9 parts of ethanol and 12.1 parts of deionized water. The other preparation methods are exactly the same as those in Example 1.

[0064] Comparative Example 4

[0065] The difference from Example 1 is that the aqueous phase is a mixture of 0 parts of ethanol and 10 parts of deionized water. The other preparation methods are exactly the same as those of Example 1.

[0066] Comparative Example 5

[0067] The difference from Example 1 is that the aqueous phase is a mixture of 10 parts of ethanol and 0 parts of deionized water. The other preparation methods are exactly the same as those in Example 1.

[0068] Comparative Example 6

[0069] The difference from Example 1 is that only the water-in-oil silicone oil emulsion is prepared without preparing the coating binder, and the water-in-oil silicone oil emulsion is directly applied to the surface of the base material, and then subjected to vacuum defoaming treatment at room temperature; after the defoaming is completed, it is cured at 60°C for 4 hours, and then dried at 105°C for 24 hours to obtain a porous PDMS coating; finally, the cured coating surface is slightly polished with 800-mesh sandpaper to obtain SHC-PDMS. The other preparation methods are exactly the same as those in Example 1.

[0070] Comparative Example 7

[0071] The difference from Example 1 is that only the coating binder is used, and no water-in-oil silicone oil emulsion is prepared, and the coating binder is directly sprayed evenly on the surface of the substrate and then pre-cured for 8 hours. The other preparation methods are exactly the same as those in Example 1.

[0072] The following properties were measured on the fluorine-free overall super-hydrophobic coating materials of the examples and comparative examples.

[0073] Material contact angle and rolling angle test: The contact angle test uses a contact angle tester to measure the contact angle between the horizontal coating material surface and water. The rolling angle test requires measuring the angle between the sample surface and the horizontal plane when the water droplet begins to roll spontaneously on the sample surface (as the sample inclination angle gradually increases, the water droplet begins to roll spontaneously). The rolling angle is taken from 3 sample surfaces with the same ratio, and each surface is measured 3 times on average. The average value of the 9 contact angles or rolling angles represents the contact angle or rolling angle between the coating material surface and water.

[0074] Material wear resistance test: Under a pressure of 20kPa, the coating sample is horizontally moved 300cm on the surface of 1000-grit sandpaper. Then the contact angle after friction is tested according to the contact angle and rolling angle test methods. Three sample surfaces are taken with the same ratio, and each surface is measured 3 times on average. The average value of the 9 contact angles or rolling angles represents the contact angle or rolling angle of the coating material surface after friction.

[0075] Material hardness test: The hardness test refers to the specification GB / T 6739-2022. Use a pencil lead of specified geometry to press down on the coating surface at a 45° angle under a load of (7.35±0.15)N. Push the pencil horizontally to measure the scratches on the coating surface by pencils of different hardness. The hardest pencil model without obvious scratch defects indicates the coating hardness. The pencil hardness index is shown in Table 1.

[0076] Table 1 Pencil hardness index

[0077]

[0078] The present invention is fluorine-free overall super-hydrophobic coating material, each implementation and comparative performance test data, test results are shown in Table 2, the present invention uses PDMS, polyethylene as oily materials, ethanol / water solution as aqueous phase material, and adopts non-solvent phase separation method to prepare a class of fluorine-free overall super-hydrophobic coating materials. Such coatings have overall super-hydrophobicity, high wear resistance, and advantages such as fluorine-free. The aqueous solution has excellent protective properties. The water contact angle is greater than 153°, and the rolling angle is less than 7°; thanks to the overall super-hydrophobicity of the coating material itself, 1000 mesh sand is used, and after rubbing a horizontal distance of 300cm under 20kPa pressure, the contact angle and rolling angle remain substantially unchanged.

[0079] As can be seen from the comparison of Example 1, Example 3, Comparative Example 3 and Comparative Example 4, the mixing ratio of water to oil phase increases, super-hydrophobicity increases first and then decreases, and the material hardness decreases continuously. As can be seen from the comparison of Example 1 and Comparative Example 1, the polyethylene powder mixing ratio increases, super-hydrophobicity is slightly improved, and the hardness of the coating material is significantly increased, which is conducive to improving the wear resistance of the cured material itself. However, it should be noted that the addition of excessive polyethylene powder will cause the rheological properties of the coating emulsion to deteriorate, which is not conducive to subsequent applications.

[0080] From the comparison of Example 1, Comparative Example 4 and Comparative Example 5, it can be seen that the proportion of ethanol in the water phase cannot be too small, otherwise the pore content in the upper part of the coating is very low, resulting in weak hydrophobicity in the upper part. This is because the ethanol content is low, and the density of the water phase will be significantly greater than that of the oil phase, causing the vacuole to sink. However, if the proportion of ethanol in the water phase is too high, the water phase vacuole in the PDMS layer will continue to gather at the top due to the high buoyancy, and it is very easy to merge into a large vacuole, which eventually leads to demulsification, and there is no microporous rough structure inside the cured PDMS.

[0081] From the comparison of Example 1, Comparative Example 6 and Comparative Example 7, it can be seen that the PDMS surface layer is the core part that provides super-hydrophobicity, and the epoxy adhesive layer is not enough to achieve super-hydrophobicity. However, if there is only a PDMS surface layer, the adhesion between it and the substrate is poor. For example, the coating prepared by the method of Comparative Example 6 can be easily torn off from the substrate surface.

[0082] Table 2 Performance test data of various embodiments and comparative examples of the fluorine-free overall super hydrophobic coating material of the present invention

[0083]

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fluorine-free overall super-hydrophobic coating material, characterized in that: The invention comprises an epoxy resin bonding layer and a super-hydrophobic polydimethylsiloxane surface layer loaded on the surface of the epoxy resin bonding layer; the epoxy resin bonding layer is composed of an epoxy resin main agent, an epoxy resin curing agent and acetone; the super-hydrophobic polydimethylsiloxane surface layer is composed of a PDMS main agent, a PDMS curing agent, polyethylene powder and an aqueous solvent.

2. The fluorine-free overall super-hydrophobic coating material according to claim 1, characterized in that: The epoxy resin main agent is one or more of bisphenol A epoxy resin E12, E20, E44, E51, bisphenol F epoxy resin NPEF-170, NPEF-187 or 4,5-epoxytetrahydrophthalic acid diglycidyl ester; Or, the epoxy resin curing agent is one or more of polyetheramine curing agent D230, T403, D400, D2000, FL1000, polyamide curing agent 650, 651, T31 modified amine curing agent, ethylenediamine curing agent or xylenediamine curing agent.

3. The fluorine-free overall super-hydrophobic coating material according to claim 1, characterized in that: The mass ratio of the epoxy resin main agent to the epoxy resin curing agent is (2.5-3.5):1; the mass ratio of the epoxy resin main agent to acetone is (1-1.8):

1.

4. The fluorine-free overall super-hydrophobic coating material according to claim 1, characterized in that: The PDMS main agent and PDMS curing agent are one or more of Dow Corning SYLGARD 184 and its supporting curing agent, Dow Corning SYLGARD 182 and its supporting curing agent, or Momentive RTV615 and its supporting curing agent; Or, the aqueous phase solvent is a solvent composed of ethanol and water; Alternatively, the particle size of the polyethylene powder is 5 to 7 μm, and the number average molecular weight of the polyethylene powder is 50,000 to 80,000.

5. The fluorine-free overall super-hydrophobic coating material according to claim 4, characterized in that: The mass ratio of the PDMS main agent to the PDMS curing agent is 10:(0.8-1.5); the mass ratio of the polyethylene powder to the PDMS main agent is (1-3):5; the mass ratio of the ethanol to water is (0.15-0.25):1; and the mass ratio of the PDMS main agent to the aqueous phase solvent is 1:(0.6-1.2).

6. A method for preparing the fluorine-free overall super-hydrophobic coating material according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) polyethylene powder, PDMS main agent, and PDMS curing agent are mixed to prepare mixed silica gel, and then an aqueous phase solvent formed by mixing water and ethanol is added dropwise to the mixed silica gel to prepare a water-in-oil silicone oil emulsion; (2) mixing acetone, an epoxy resin main agent, and an epoxy curing agent to prepare an epoxy resin adhesive; spraying the epoxy resin adhesive on the surface of the substrate, and pre-curing to form an epoxy resin adhesive layer; (3) applying a water-in-oil silicone oil emulsion on the surface of the epoxy resin bonding layer, and forming a super-hydrophobic polydimethylsiloxane surface layer after vacuum defoaming, curing and drying; and polishing the super-hydrophobic polydimethylsiloxane surface layer to form a fluorine-free overall super-hydrophobic coating material.

7. The method for preparing the fluorine-free overall super-hydrophobic coating material according to claim 6, characterized in that: In step (2), the compressed air pressure used for spraying is 0.15-0.35 MPa, the diameter of the spray pen is 0.3 mm, and the distance between the nozzle and the substrate is 4-6 cm; Alternatively, the pre-curing is: curing at 20 to 28° C. for 6 to 10 hours.

8. The method for preparing the fluorine-free overall super-hydrophobic coating material according to claim 6, characterized in that: In step (3), the vacuum defoaming is: defoaming for 10 to 20 minutes at room temperature under an air pressure of -0.09 to -0.05 MPa; Or, the curing is: curing at 55-70° C. for 4-8 hours; Or, the drying is: drying at 100-115° C. for 12-24 hours.

9. The method for preparing the fluorine-free overall super-hydrophobic coating material according to claim 6, characterized in that: In step (3), the polishing is performed using 300-1000 mesh sandpaper at a pressure of 15-25 kPa; Alternatively, the thickness of the fluorine-free overall super-hydrophobic coating material is 0.5 to 2 mm.

10. Use of the fluorine-free integral super-hydrophobic coating material according to any one of claims 1 to 5 in special engineering structure protection, metal mechanical corrosion protection or oil-water separation.

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