Transparent super-hydrophobic peelable composite coating as well as preparation method and application thereof

Abstract

The invention discloses a transparent super-hydrophobic peelable composite coating which comprises a transparent peelable bottom layer and a transparent super-hydrophobic surface layer, finish paint adopted by the transparent super-hydrophobic surface layer comprises the following components in parts by volume: 100 parts of SiO2 transparent dispersion liquid, 0.3-3 parts of a low surface energy modifier and 1-4 parts of a first silane coupling agent; a primer adopted by the transparent peelable bottom layer is prepared from the following components in parts by weight: 15 to 20 parts of water-based resin, 0.1 to 0.3 part of hydrophilic particles, 0.2 to 0.5 part of a second silane coupling agent, 0.3 to 0.5 part of a film forming agent, 0.3 to 0.6 part of a de-foaming agent and 0.3 to 0.5 part of a wetting agent. The transparent super-hydrophobic surface layer and the transparent peelable bottom layer are combined, and good light transmittance, hydrophobicity and peelable performance can be considered; the preparation method is simple, mild in reaction condition, simple to operate, low in cost and suitable for popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, and in particular relates to a transparent super-hydrophobic peelable composite coating and a preparation method and application thereof. Background Art

[0002] Materials, instruments, parts and components are easily scratched, worn, contaminated, and eroded by salt spray, moisture, acid rain, microorganisms, etc. during transportation, storage, processing and assembly, which can lead to chemical corrosion and electrochemical corrosion, affecting the appearance of the equipment and even causing performance degradation. In order to reduce these damages and extend the service life of the equipment, coatings are usually applied to its surface. However, traditional coatings cannot usually be removed by peeling, pulling or simple physical or chemical methods.

[0003] As a special functional coating, peelable coating is applied to the surface of the material workpiece. After drying, it can form a closed protective film to play a temporary protective role. After completing the protection task, the coating can be completely peeled off by hand, and the surface of the workpiece still maintains its original appearance and performance. Existing peelable coatings mainly include solvent-based and water-based. Among them, solvent-based peelable coatings are widely used, but the disadvantage is that they contain a large amount of volatile organic compounds (VOCs), have poor safety, and pollute the environment; water-based peelable coatings have the advantages of low VOC, green environmental protection, and easy construction, but they are greatly affected by the environment. For example, under conditions of high temperature and high humidity, the protective performance of the coating may be greatly affected, thereby affecting the paint on the surface of the product or damaging the surface of the product.

[0004] Transparent peelable coatings protect the surface of items without affecting their overall aesthetics. The use of transparent coatings can clearly show the internal conditions of items, making it easier for users or inspectors to observe the status of items; in the field of electronic products, transparent coatings can be used to protect internal components such as circuit boards, while facilitating inspection and repair.

[0005] At present, most transparent peelable coatings are hydrophilic, which can easily lead to water absorption, swelling, blistering and other problems, thus affecting their adhesion and peeling performance. Especially in a humid environment, the stability of the coating will be further reduced. Some studies have adopted a double-layer coating design to improve the hydrophobic properties of the peelable coating surface; however, after spraying a transparent topcoat on a transparent primer, it is easy to cause a significant decrease in the transparency of the film due to the influence of various factors such as coating composition and reaction, coating thickness and drying, pollution and impurities, compatibility of primer and topcoat, coating surface state and environment. On the basis of maintaining the transparency of the peelable coating, it is a challenging problem to further build superhydrophobic properties. Summary of the invention

[0006] The main purpose of the present invention is to provide a super-hydrophobic transparent peelable composite coating to address the deficiencies in the prior art, which can take into account good light transmittance, hydrophobicity and peelability, and is expected to be applied to solar panels, windows and glass curtain walls, automobile windshields, cultural relics protection and other fields; and the preparation method involved is simple and easy, the reaction conditions are mild, and it is environmentally friendly, and can be promoted and applied on a large scale.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A transparent super-hydrophobic strippable composite coating comprises a transparent strippable bottom layer and a transparent super-hydrophobic surface layer, wherein the topcoat used in the transparent super-hydrophobic surface layer comprises: 100 parts of SiO2 transparent dispersion, 0.3-3 parts of a low surface energy modifier, and 1-4 parts of a first silane coupling agent; and the primer used in the transparent strippable bottom layer comprises: 15-20 parts of a water-based resin, 0.1-0.3 parts of hydrophilic particles, 0.2-0.5 parts of a second silane coupling agent, 0.3-0.5 parts of a film former, 0.3-0.6 parts of a defoamer, and 0.3-0.5 parts of a wetting agent.

[0009] In the above scheme, the water-based resin can be selected from one or more of water-based polyurethane, water-based polyurethane, water-based cellulose, water-based modified polybutadiene, water-based acrylic acid, and the like.

[0010] In the above scheme, the hydrophilic particles are one or more of hydrophilic fumed silica, titanium dioxide, and iron hydroxide; and the average particle size thereof is 15 to 50 nm.

[0011] In the above solution, the first silane coupling agent and the second coupling agent are respectively one or more of KH550, KH560, KH570, etc.

[0012] Furthermore, the first silane coupling agent is diluted with an alcohol solvent before use.

[0013] Furthermore, the volume ratio of the first silane coupling agent to the alcohol solvent is 1:0.5-1.

[0014] Furthermore, the defoaming agent can be selected from one or more of a foam-breaking polysiloxane defoaming agent, a polymethylalkylsiloxane defoaming agent, a polydimethylsiloxane defoaming agent, and the like.

[0015] In the above scheme, the wetting agent is one or more of propylene glycol methyl ether acetate, polyether modified polysiloxane, polyacrylamide, and polyethylene glycol.

[0016] In the above scheme, the film-forming agent is one or more of dipropylene glycol methyl ether (DPM), acrylic resin, polyurethane film-forming agent and the like.

[0017] In the above scheme, the low surface energy modifier is one or more of hexamethyldisilazane, methyltriethoxysilane, hexadecyltrimethoxysilane, perfluorodecyltrimethoxysilane and the like.

[0018] In the above scheme, the SiO2 transparent dispersion is obtained by adding a silicon source, an alkali solution and a first surfactant into an alcohol solvent and stirring the mixture.

[0019] In the above scheme, the alkali solution is NaOH solution, KOH solution or ammonia solution, wherein the concentration of NaOH solution and KOH solution is 1-1.8 mol / L, and the concentration of ammonia solution is 25-29 wt%.

[0020] In the above scheme, the silicon source is one or more of tetraethyl orthosilicate, tetrabutyl orthosilicate, propyl silicate, butyl silicate, and hydrophilic fumed silica particles.

[0021] In the above scheme, the alcohol solvent is one or more of ethanol, methanol, isopropanol and the like.

[0022] In the above scheme, during the preparation of the SiO2 transparent dispersion, the volume ratio of the alcohol solvent, the alkali solution, the silicon source, and the first silane coupling agent is (80-100):(0.1-0.5):(3-5):(1-4).

[0023] Furthermore, the molar ratio of the silicon source to the OH- introduced into the alkali solution is 100:0.3-0.5.

[0024] In the above scheme, the stirring treatment time is 1h to 24h.

[0025] Furthermore, when the silicon source is one or more of tetraethyl orthosilicate, tetrabutyl orthosilicate, propyl silicate, and butyl silicate, a hydrolysis reaction is first performed (12 to 24 hours) and then aged (1 to 3 days).

[0026] Furthermore, when the silicon source is hydrophilic fumed silica particles, the stirring treatment time is 1 to 2 hours.

[0027] The method for preparing the above-mentioned transparent super-hydrophobic peelable coating material comprises the following steps:

[0028] (1) adding an alkali solution, a silicon source, and a first silane coupling agent to an alcohol solvent, mixing them, and performing a hydrolysis reaction to obtain a transparent SiO2 dispersion;

[0029] (2) adding a low surface energy modifier to the transparent SiO2 dispersion obtained in step (1), stirring and reacting, thereby obtaining a transparent super-hydrophobic SiO2-based topcoat;

[0030] (3) adding hydrophilic particles, a second silane coupling agent, a defoamer, a wetting agent, and a film-forming agent to the water-based resin and stirring the mixture to obtain a transparent peeling primer;

[0031] (4) coating the obtained transparent peeling primer on the surface of the substrate, and after the primer is dried, spraying the obtained transparent super-hydrophobic SiO2-based topcoat on the surface, and drying, thereby obtaining the transparent super-hydrophobic peelable composite coating.

[0032] In the above scheme, during the preparation process of steps (1) to (4), the ambient temperature is room temperature.

[0033] In the above scheme, the stirring reaction time in step (2) is 6 to 12 hours.

[0034] In the above scheme, the stirring time in step (3) is 0.5 to 1 h.

[0035] In the above solution, the transparent peeling primer can be coated by brushing or spraying.

[0036] Furthermore, when the transparent peeling primer is sprayed, the specific parameter conditions include: the spray gun diameter is 0.8-1.0 mm, the air pressure is 0.4-0.7 MPa; the spraying angle is perpendicular to the substrate; the spraying distance is 15-20 cm; the spray width is 10-15 cm.

[0037] Furthermore, the spraying is performed more than 2 times using the above parameter conditions.

[0038] Furthermore, the transparent peelable bottom layer has a thickness of 15 to 25 μm.

[0039] In the above scheme, the topcoat spraying needs to be carried out after the primer is dry, and the topcoat should be sprayed 20 to 30 minutes after the primer spraying is completed.

[0040] Furthermore, the spraying process parameters of the transparent super-hydrophobic SiO2-based topcoat include: a spray gun caliber of 0.8 to 1.0 mm, an air pressure of 0.4 to 0.7 MPa; a spraying angle perpendicular to the substrate; a spraying distance of 25 to 30 cm; and a spray width of 10 to 15 cm.

[0041] Furthermore, the transparent super-hydrophobic SiO2 dispersion is sprayed 1 to 2 times.

[0042] Furthermore, the transparent super-hydrophobic surface layer has a dry thickness of 15 to 25 μm.

[0043] In the above scheme, step (4) is to spray the transparent super-hydrophobic / super-amphiphobic SiO2 dispersion prepared in step (2) onto the peelable transparent coating prepared in step (3) to obtain a transparent super-hydrophobic / super-amphiphobic peelable coating.

[0044] The principle of the present invention is:

[0045] The present invention carries out layered design for the transparent super-hydrophobic / super-amphiphobic strippable coating material: the primer uses water-based resin as the main raw material, and introduces a small amount of hydrophilic particles and silane coupling agent, which can promote the increase of the bonding ability of the primer and the topcoat, and is also beneficial to improve the transmittance, stripping property and strength of the obtained paint film; the topcoat uses SiO2 transparent dispersion liquid, low surface energy modifier and silane coupling agent as the main raw materials, and is combined with a spraying process, so that a transparent surface layer with good super-hydrophobic performance can be further constructed on the surface of the transparent strippable bottom layer, ensuring good visible light transmittance, and further achieving an anti-reflection effect, and is expected to be applied to solar panels, windows and glass curtain walls, automobile windshields, cultural relics protection and other fields.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1) The present invention combines a transparent super-hydrophobic surface layer with a transparent peelable bottom layer for the first time, and the resulting composite coating can maintain high light transmittance while taking into account good super-hydrophobic properties and peelable properties;

[0048] 2) The water-based strippable primer used has the advantages of low VOC, green and environmentally friendly, easy to construct, and is environmentally friendly;

[0049] 3) The preparation method of the present invention is simple, the reaction conditions are mild, the operation is simple, the cost is low, and mass production is possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a morphological photograph of a water drop added to the surface of the thin film sample prepared in Example 1 of the present invention;

[0051] Figure 2 This is a photograph of the water contact angle on the surface of the film sample prepared in Example 1 of the present invention;

[0052] Figure 3 This is a scanning electron microscope (SEM) image of a cross section of a thin film sample prepared in Example 2 of the present invention;

[0053] Figure 4 The transmittance test results of the film sample prepared in Example 2 of the present invention;

[0054] Figure 5 The photos of the film sample prepared in Example 2 of the present invention being peelable and having water drops added thereto are shown;

[0055] Figure 6 The peelability of the transparent super-amphiphobic peelable coating prepared in Example 3 of the present invention and the photos of water droplets and oil droplets added;

[0056] Figure 7This is a photograph of the oil contact angle of the transparent super-amphiphobic peelable coating prepared in Example 3 of the present invention;

[0057] Figure 8 The transmittance test result of the transparent super-amphiphobic strippable coating prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0058] The present invention is further described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] In the following embodiments, the defoaming agent used may be one or more of BYK024, BYK028, BYK346, etc.; the wetting agent used may be one or more of BYK425, BYK42, etc.

[0060] The water-based resin used is water-based polyurethane, which is an aliphatic water-based polyurethane resin with a transparent appearance, a viscosity of 350MPa.S at room temperature, a specific gravity of 1.06KG / 1, a solid content of 38%, a rebound resilience of 380%, an elongation ratio of 400%, and a tensile strength of 10MPa.

[0061] Example 1

[0062] A transparent super-hydrophobic peelable composite coating, the preparation method of which comprises the following steps:

[0063] (1) Under room temperature magnetic stirring, add 0.3 ml of 1.8 M NaOH solution to 100 ml of ethanol, then add 4 ml of diluted KH550 solution (the volume ratio of KH500 to ethanol is 3:2), stir for 10 min, then slowly add 3 ml of tetraethyl orthosilicate, hydrolyze at room temperature for 12 h to obtain a silicon dispersion, and let it stand for 3 days;

[0064] (2) 3 ml of hexamethyldisilazane was uniformly dispersed in the dispersion obtained in step (1), and then reacted under magnetic stirring for 12 h to obtain a transparent super-hydrophobic dispersion, which was recorded as topcoat;

[0065] (3) Under magnetic stirring at room temperature, 0.2 g of hydrophilic fumed silica (average particle size of 15 nm) and 0.5 g of KH550 were added to 20 g of waterborne polyurethane, and the mixture was stirred for 30 min. Then, 0.2 g of BYK024, 0.2 g of BYK028, and 0.2 g of BYK346 were added, and the mixture was stirred for 10 min. Then, 0.2 g of BYK425 and 0.2 g of BYK420 were added, and the mixture was stirred for 10 min. Finally, 0.4 g of DPM (dipropylene glycol methyl ether) was added, and the mixture was stirred for 30 min to obtain a transparent peelable coating, which was recorded as a primer.

[0066] (4) Preparation of a transparent super-hydrophobic peelable composite coating: first use the primer prepared in step (3) to spray the primer evenly on the glass substrate. During spraying, stir the primer thoroughly and evenly, and then mature it for 2 minutes before use. When pouring the primer into the spray gun, filter it with a 100-mesh filter cloth. The primer spraying process includes: using an Iwata W-71 air spray gun (caliber selected is 0.8 mm), air pressure: 0.5 MPa; spraying angle: perpendicular to the substrate; spraying distance: 15 cm; spray width: 10 cm; spraying 2 times;

[0067] The method comprises the following steps: standing at room temperature for 10-20 minutes, and spraying the topcoat after the surface is dried (the actual dry thickness of the primer is 30 μm±20 μm); shaking the topcoat up and down for about 5 minutes before spraying the topcoat, and filtering the topcoat with a 100-mesh filter cloth when pouring the topcoat into the spray gun; the topcoat spraying process comprises: using an Iwata W-71 air spray gun (the caliber is selected to be 0.8 mm), an air pressure of 0.5 MPa, a spraying angle of perpendicular to the substrate, a spraying distance of 25 cm, a spray width of 10 cm, spraying twice (the actual dry thickness of the topcoat is 20 μm±5 μm); and after the topcoat is actually dried, the transparent super-hydrophobic peelable composite coating is obtained.

[0068] The morphology of the surface of the transparent super-hydrophobic strippable composite coating sample obtained in this embodiment is as follows: Figure 1 It can be seen that the surface of the composite coating has good superhydrophobic properties. Figure 2 It represents the contact angle of water, where the contact angle of water is 160.5°.

[0069] Example 2

[0070] A transparent super-hydrophobic peelable composite coating, the preparation method of which comprises the following steps:

[0071] (1) Under magnetic stirring at room temperature, add 2 ml of ammonia solution (concentration of 25 wt%) to 100 ml of ethanol, then add 4 ml of diluted KH550 solution (the volume ratio of KH500 to ethanol is 3:2), stir for 10 min, then slowly add 4 ml of tetraethyl orthosilicate, hydrolyze at room temperature for 12 h to obtain a silicon dispersion, and let it stand for 3 days;

[0072] (2) 4 ml of hexamethyldisilazane was uniformly dispersed in the dispersion obtained in step (1), and then reacted for 12 h under magnetic stirring to obtain a transparent super-hydrophobic dispersion, which was recorded as topcoat;

[0073] (3) Under magnetic stirring at room temperature, 0.2 g of hydrophilic fumed silica (average particle size of 15 nm) and 0.5 g of KH550 were added to 20 g of waterborne polyurethane, and the mixture was stirred for 30 min. Then, 0.2 g of BYK024, 0.2 g of BYK028, and 0.2 g of BYK346 were added, and the mixture was stirred for 10 min. Then, 0.2 g of BYK425 and 0.2 g of BYK420 were added, and the mixture was stirred for 10 min. Then, 0.4 g of DPM (dipropylene glycol methyl ether) was added, and the mixture was stirred for 30 min to obtain a transparent peelable coating, which was recorded as a primer.

[0074] (4) Preparation of a transparent super-hydrophobic peelable composite coating: first use the primer prepared in step (3) to spray the primer evenly on the glass substrate. During spraying, stir the primer thoroughly and evenly, and then mature it for 2 minutes before use. When pouring the primer into the spray gun, filter it with a 100-mesh filter cloth. The primer spraying process includes: using an Iwata W-71 air spray gun (caliber selected is 1.0 mm), air pressure: 0.7 MPa; spraying angle: perpendicular to the substrate; spraying distance: 20 cm; spray width: 5 cm; spraying 2 times;

[0075] The method comprises the following steps: standing at room temperature for 10-20 minutes, and spraying the topcoat after the surface is dried (the actual dry thickness of the primer is 30 μm±20 μm); shaking the topcoat up and down for about 5 minutes before spraying the topcoat, and filtering the topcoat with a 100-mesh filter cloth when pouring the topcoat into the spray gun; the topcoat spraying process comprises: using an Iwata W-71 air spray gun (the caliber is selected to be 1.0 mm), an air pressure of 0.7 MPa, a spraying angle of perpendicular to the substrate, a spraying distance of 30 cm, a spray width of 5 cm, spraying twice (the actual dry thickness of the topcoat is 20 μm±5 μm); and after the topcoat is actually dried, the transparent super-hydrophobic peelable composite coating is obtained.

[0076] Figure 3 This is a SEM photograph of the transparent super-hydrophobic strippable composite coating obtained in this embodiment. It can be seen that the transparent super-hydrophobic coating and the transparent strippable coating are tightly combined, proving that the composite of the primer and the topcoat is successful; the surface layer structure is utilized to ensure good super-hydrophobic properties, and is beneficial to reduce light reflection to a certain extent, thereby improving the visible light transmittance of the obtained paint film.

[0077] Figure 4The transmittance test results of the super-hydrophobic peelable composite coating obtained in this embodiment show that, within the wavelength range of 300-1100nm, the average transmittance of ordinary glass (without the composite coating described in the present invention) is 86.4%, while the average transmittance of the present invention after the composite coating described in the present invention is set is 89.7%, which can show a good anti-reflection effect.

[0078] Figure 5 The test results of the peeling performance and hydrophobic performance of the super hydrophobic peelable composite coating obtained in this embodiment show that the composite coating obtained in the present invention can be easily peeled off from the surface of the substrate and its surface has good hydrophobic performance.

[0079] Example 3

[0080] A transparent super-amphiphobic peelable composite coating, the preparation method of which comprises the following steps:

[0081] (1) Under room temperature and magnetic stirring conditions, add 0.6 ml of 1.6 M potassium hydroxide solution to 100 ml of ethanol, then add diluted KH550 solution (the volume ratio of KH500 to ethanol is 3:2), stir for 10 min, then slowly add 1 g of hydrophilic fumed silica and stir for 1 h;

[0082] (2) 0.5 ml of perfluorodecyltrimethoxysilane and 6 ml of deionized water are uniformly dispersed in the dispersion obtained in step (1), and then reacted for 12 hours under magnetic stirring to obtain a transparent super-amphiphobic dispersion, which is recorded as topcoat;

[0083] (3) Under magnetic stirring at room temperature, 0.2 g of hydrophilic fumed silica (average particle size of 30 nm) and 0.5 g of KH550 were added to 20 g of waterborne polyurethane, and the mixture was stirred for 30 min. Then, 0.2 g of BYK024, 0.2 g of BYK028 and 0.2 g of BYK346 were added, and the mixture was stirred for 10 min. Then, 0.2 g of BYK425 and 0.2 g of BYK420 were added, and the mixture was stirred for 10 min. After stirring for 10 min, 5 ml of deionized water was added, and the mixture was stirred for 10 min. Finally, 0.4 g of DPM was added, and the mixture was stirred for 30 min to obtain a transparent peelable coating, which was recorded as a primer.

[0084] (4) Preparation of transparent super-amphiphobic peelable composite coating: first use the primer prepared in step (3) to spray the primer evenly on the glass substrate. When spraying, stir the primer thoroughly and evenly, and then mature it for 2 minutes before use; use a 100-mesh filter cloth to filter the primer into the spray gun; the primer spraying process includes: using an Iwata W-71 air spray gun (caliber 1.0 mm), air pressure: 0.4 MPa; spraying angle: perpendicular to the substrate; spraying distance: 15 cm; spray width: 15 cm. Spray twice;

[0085] The method comprises the following steps: standing at room temperature for 10-20 minutes, and spraying the topcoat after the surface is dried (the actual dry thickness of the primer is 30 μm±20 μm); shaking the topcoat up and down for about 5 minutes before spraying the topcoat, and filtering the topcoat with a 100-mesh filter cloth when pouring the topcoat into the spray gun; the topcoat spraying process comprises: using an Iwata W-71 air spray gun (caliber 0.8 mm), air pressure: 0.4 MPa; spraying angle: perpendicular to the substrate; spraying distance: 25 cm; spray width: 15 cm; spraying twice (the actual dry thickness of the topcoat is 20 μm±5 μm); after the topcoat is actually dried, the transparent super-hydrophobic peelable composite coating is obtained.

[0086] Figure 6 The peelability and super-amphiphobic performance test results of the composite coating obtained in this embodiment (blue represents water droplets, and transparent represents oil droplets). It can be seen that the composite coating obtained can exhibit super-amphiphobic properties of super-hydrophobicity and super-oleophobicity while ensuring easy peeling.

[0087] Figure 7 is the oleophobic angle of this embodiment, which proves the good super oleophobic performance of this embodiment, and the oil contact angle reaches 163.8°.

[0088] Figure 8 From the average transmittance test results of ordinary glass and the composite coating obtained in this embodiment within the wavelength range of 300-1100nm, it can be seen that the average transmittance of ordinary glass (uncoated) is 86.4%, while the average transmittance after providing the composite coating described in the present invention is 90%, which has excellent light transmittance.

[0089] Comparative Example 1

[0090] A hydrophobic composite coating, the preparation method of which comprises the following steps:

[0091] (1) Under the condition of magnetic stirring at room temperature, 0.3 ml of 1.8 M NaOH solution was added to 100 ml of ethanol solvent, and 3 ml of tetraethyl orthosilicate was slowly added after stirring for 10 min. The silicon dispersion was hydrolyzed at room temperature for 12 h to obtain the silicon dispersion, and then aged for 3 days;

[0092] (2) 3 ml of hexamethyldisilazane was uniformly dispersed in the dispersion obtained in step (1), and then reacted for 12 h under magnetic stirring to obtain a transparent super-hydrophobic dispersion, which was recorded as topcoat;

[0093] (3) Under magnetic stirring at room temperature, 0.2 g BYK024, 0.2 g BYK028 and 0.2 g BYK346 were added to 20 g of waterborne polyurethane, and the mixture was stirred for 10 min. Then, 0.2 g BYK425 and 0.2 g BYK420 were added, and the mixture was stirred for 10 min. Finally, 0.4 g DPM (dipropylene glycol methyl ether) was added, and the mixture was stirred for 30 min to obtain a transparent peelable coating, which was recorded as a primer.

[0094] (4) Preparation of a transparent super-amphiphobic peelable composite coating: first use the primer prepared in step (3) to spray the primer evenly on the glass substrate. During spraying, stir the primer thoroughly and evenly, and then mature it for 2 minutes before use. When pouring the primer into the spray gun, filter it with a 100-mesh filter cloth. The primer spraying process includes: using an Iwata W-71 air spray gun (caliber 0.8 mm), air pressure: 0.5 MPa; spraying angle: perpendicular to the substrate; spraying distance: 15 cm; spray width: 10 cm; spraying 2 times;

[0095] The method comprises the following steps: standing at room temperature for 10-20 minutes, and spraying the topcoat after the surface is dried (the actual dry thickness of the primer is 30 μm±20 μm); shaking the topcoat up and down for about 5 minutes before spraying the topcoat, and filtering the topcoat with a 100-mesh filter cloth when pouring the topcoat into the spray gun; the topcoat spraying process comprises: using an Iwata W-71 air spray gun (caliber 0.8 mm), air pressure: 0.5 MPa; spraying angle: perpendicular to the substrate; spraying distance: 25 cm; spray width: 10 cm; spraying twice (the actual dry thickness of the topcoat is 20 μm±5 μm); after the topcoat is actually dried, the transparent super-hydrophobic peelable composite coating is obtained.

[0096] The obtained sample was tested for hydrophobic and oleophobic angles, where the hydrophobic angle was 122.8°, the oleophobic angle was 62.3°, and the average light transmittance was 83.2% within the visible light range (380-780nm). The obtained hydrophobic composite coating was difficult to completely peel off from the surface of the glass slide.

[0097] Comparative Example 2

[0098] A hydrophobic composite coating, the preparation method of which comprises the following steps:

[0099] (1) Under room temperature magnetic stirring conditions, add 0.3 ml of 1.8 M NaOH solution to 100 ml of ethanol solvent, then add 4 ml of diluted KH550 solution (the volume ratio of KH500 to ethanol is 3:2), stir for 10 min, then slowly add 3 ml of tetraethyl orthosilicate, hydrolyze at room temperature for 12 h to obtain a silicon dispersion, and let it stand for 3 days;

[0100] (2) 3 ml of hexamethyldisilazane was uniformly dispersed in the dispersion obtained in step (1), and then reacted for 12 h under magnetic stirring to obtain a transparent super-hydrophobic dispersion, which was recorded as topcoat;

[0101] (3) Under magnetic stirring at room temperature, 0.2 g BYK024, 0.2 g BYK028, and 0.2 g BYK346 were added to 20 g of waterborne polyurethane, and the mixture was stirred for 10 min. Then, 0.2 g BYK425 and 0.2 g BYK420 were added, and the mixture was stirred for 10 min. Finally, 0.4 g DPM (dipropylene glycol methyl ether) was added, and the mixture was stirred for 30 min to obtain a transparent peelable coating, which was recorded as a primer.

[0102] (4) Preparation of a transparent super-amphiphobic peelable composite coating: first use the primer prepared in step (3) to spray the primer evenly on the glass substrate. During spraying, stir the primer thoroughly and evenly, and then mature it for 2 minutes before use. When pouring the primer into the spray gun, filter it with a 100-mesh filter cloth. The primer spraying process includes: using an Iwata W-71 air spray gun (caliber 0.8 mm), air pressure: 0.5 MPa; spraying angle: perpendicular to the substrate; spraying distance: 15 cm; spray width: 10 cm, and spraying twice;

[0103] The mixture was allowed to stand for 10-20 minutes at room temperature, and then the topcoat was sprayed after the surface was dried (the actual dry thickness of the primer was 30 μm±20 μm); the topcoat was shaken up and down for about 5 minutes before spraying, and a 100-mesh filter cloth was used to filter the mixture into the spray gun; the topcoat spraying process included: using an Iwata W-71 air spray gun (caliber 0.8 mm), air pressure: 0.5 MPa; spraying angle: perpendicular to the substrate; spraying distance: 25 cm; spray width: 10 cm; spraying twice (the actual dry thickness of the topcoat was 20 μm±5 μm); after the topcoat was dried, the transparent super-hydrophobic peelable composite coating was obtained.

[0104] The obtained samples were tested for hydrophobic and oleophobic angles, where the hydrophobic angle was 157.2°, the oleophobic angle was 125.6°, and the average light transmittance within the visible light range (380-780nm) was 86.2% (the average transmittance of the glass substrate was 86.4%), which reduced the overall light transmittance of the obtained samples to a certain extent, and the obtained hydrophobic composite coating was difficult to completely peel off from the surface of the glass slide.

[0105] Comparative Example 3

[0106] A hydrophobic composite coating, the preparation method of which comprises the following steps:

[0107] (1) Under magnetic stirring at room temperature, add 0.3 ml of 1.8 M NaOH solution to 100 ml of ethanol, stir for 10 min, then slowly add 3 ml of tetraethyl orthosilicate, hydrolyze at room temperature for 12 h to obtain a silicon dispersion, and let it stand for 3 days;

[0108] (2) 3 ml of hexamethyldisilazane was uniformly dispersed in the dispersion obtained in step (1), and then reacted for 12 h under magnetic stirring to obtain a transparent super-hydrophobic dispersion, which was recorded as topcoat;

[0109] (3) Under magnetic stirring at room temperature, 0.2 g of hydrophilic fumed silica (average particle size of 15 nm) and 0.5 g of KH550 were added to 20 g of waterborne polyurethane, and the mixture was stirred for 30 min. Then, 0.2 g of BYK024, 0.2 g of BYK028, and 0.2 g of BYK346 were added, and the mixture was stirred for 10 min. Then, 0.2 g of BYK425 and 0.2 g of BYK420 were added, and the mixture was stirred for 10 min. Finally, 0.4 g of DPM (dipropylene glycol methyl ether) was added, and the mixture was stirred for 30 min to obtain a transparent peelable coating, which was recorded as a primer.

[0110] (4) Preparation of a transparent super-amphiphobic peelable composite coating: first use the primer prepared in step (3) to spray the primer evenly on the glass substrate. During spraying, stir the primer thoroughly and evenly, and then mature it for 2 minutes before use. When pouring the primer into the spray gun, filter it with a 100-mesh filter cloth. The primer spraying process includes: using an Iwata W-71 air spray gun (caliber 1.0 mm), air pressure: 0.5 MPa; spraying angle: perpendicular to the substrate; spraying distance: 15 cm; spray width: 10 cm; spraying 2 times;

[0111] The mixture was allowed to stand for 10-20 minutes at room temperature, and then the topcoat was sprayed after the surface was dried (the actual dry thickness of the primer was 30 μm±20 μm); the topcoat was shaken up and down for about 5 minutes before spraying, and a 100-mesh filter cloth was used to filter the mixture into the spray gun; the topcoat spraying process included: using an Iwata W-71 air spray gun (caliber 0.8 mm), air pressure: 0.5 MPa; spraying angle: perpendicular to the substrate; spraying distance: 25 cm; spray width: 10 cm; spraying twice (the actual dry thickness of the topcoat was 20 μm±5 μm); after the topcoat was dried, the transparent super-hydrophobic peelable composite coating was obtained.

[0112] The obtained samples were tested for hydrophobic and oleophobic angles, where the hydrophobic angle was 145.2°, the oleophobic angle was 82.1°, and within the acceptable light range (380-780nm), the average light transmittance of the obtained samples was 83.9% (the average transmittance of the glass substrate was 86.4%), which reduced the overall light transmittance of the obtained samples.

[0113] Comparative Example 4

[0114] A hydrophobic composite coating, the preparation method of which comprises the following steps:

[0115] (1) Under room temperature magnetic stirring, add 0.3 ml of 1.8 M NaOH solution to 100 ml of ethanol, add 5 ml of diluted KH550 solution (the volume ratio of KH500 to ethanol is 3:2), stir for 10 min, then slowly add 3 ml of tetraethyl orthosilicate, hydrolyze at room temperature for 12 h to obtain a silicon dispersion, and let it stand for 3 days;

[0116] (2) 3 ml of hexamethyldisilazane was uniformly dispersed in the dispersion obtained in step (1), and then reacted for 12 h under magnetic stirring to obtain a transparent super-hydrophobic dispersion, which was recorded as topcoat;

[0117] (3) Under magnetic stirring at room temperature, 0.2 g of hydrophilic fumed silica (100 nm) and 0.5 ml of KH550 were added to 20 g of waterborne polyurethane, and the mixture was stirred for 30 min. Then, 0.2 g of BYK024, 0.2 g of BYK028, and 0.2 g of BYK346 were added, and the mixture was stirred for 10 min. Then, 0.2 g of BYK425 and 0.2 g of BYK420 were added, and the mixture was stirred for 10 min. Finally, 0.4 g of DPM (dipropylene glycol methyl ether) was added, and the mixture was stirred for 30 min to obtain a transparent peelable coating, which was recorded as a primer.

[0118] (4) Preparation of a transparent super-amphiphobic peelable composite coating: first use the primer prepared in step (3) to spray the primer evenly on the glass substrate. During spraying, stir the primer thoroughly and evenly, and then mature it for 2 minutes before use. When pouring the primer into the spray gun, filter it with a 100-mesh filter cloth. The primer spraying process includes: using an Iwata W-71 air spray gun (caliber 1.0 mm), air pressure: 0.4 MPa; spraying angle: perpendicular to the substrate; spraying distance: 15 cm; spray width: 15 cm; spraying 2 times;

[0119] The method comprises the following steps: standing at room temperature for 10-20 minutes, and spraying the topcoat after the surface is dried (the actual dry thickness of the primer is 30 μm±20 μm); shaking the topcoat up and down for about 5 minutes before spraying the topcoat, and filtering the topcoat with a 100-mesh filter cloth when pouring the topcoat into the spray gun; the topcoat spraying process comprises: using an Iwata W-71 air spray gun (caliber 0.8 mm), air pressure: 0.4 MPa; spraying angle: perpendicular to the substrate; spraying distance: 25 cm; spray width: 15 cm; spraying twice (the actual dry thickness of the topcoat is 20 μm±5 μm); after the topcoat is actually dried, the transparent super-hydrophobic peelable composite coating is obtained.

[0120] The obtained samples were tested for hydrophobic and oleophobic angles, where the hydrophobic angle was 138.4° and the oleophobic angle was 76.1°. Within the acceptable light range (380-780nm), the average light transmittance of the obtained samples was 80.6% (the average transmittance of the glass substrate was 86.4%), which reduced the overall light transmittance of the obtained samples.

[0121] The present invention is not limited to the above-mentioned embodiments. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A transparent super-hydrophobic peelable composite coating, characterized in that: The invention comprises a transparent peelable bottom layer and a transparent super-hydrophobic surface layer, wherein the topcoat used in the transparent super-hydrophobic surface layer comprises: 100 parts of SiO2 transparent dispersion, 0.3-3 parts of low surface energy modifier, and 1-4 parts of first silane coupling agent; the primer used in the transparent peelable bottom layer comprises: 15-20 parts of water-based resin, 0.1-0.3 parts of hydrophilic particles, 0.2-0.5 parts of second silane coupling agent, 0.3-0.5 parts of film former, 0.3-0.6 parts of defoamer, and 0.3-0.5 parts of wetting agent.

2. The transparent super-hydrophobic peelable composite coating according to claim 1, characterized in that: The water-based resin is one or more of water-based polyurethane, water-based polyurethane, water-based cellulose, water-based modified polybutadiene, and water-based acrylic acid.

3. The transparent super-hydrophobic peelable composite coating according to claim 1, characterized in that: The hydrophilic particles are one or more of hydrophilic fumed silica, titanium dioxide, and ferric hydroxide; and the average particle size thereof is 15 to 50 nm.

4. The transparent super-hydrophobic peelable composite coating according to claim 1, characterized in that: The defoaming agent is one or more of a foam-breaking polysiloxane defoaming agent, a polymethyl alkyl siloxane defoaming agent, and a polydimethyl siloxane defoaming agent; the wetting agent is one or more of propylene glycol methyl ether acetate, polyether-modified polysiloxane, polyacrylamide, and polyethylene glycol.

5. The transparent super-hydrophobic strippable composite coating according to claim 1, characterized in that: The film-forming agent is one or more of dipropylene glycol methyl ether, acrylic resin, and polyurethane; the low surface energy modifier is one or more of hexamethyldisilazane, methyltriethoxysilane, hexadecyltrimethoxysilane, and perfluorodecyltrimethoxysilane.

6. The transparent super-hydrophobic peelable composite coating according to claim 1, characterized in that: The SiO2 transparent dispersion is obtained by adding a silicon source, an alkali solution and a first surfactant into an alcohol solvent and stirring the mixture.

7. The transparent super-hydrophobic strippable composite coating according to claim 6, characterized in that: The volume ratio of the alcohol solvent, the alkali solution, the silicon source and the first silane coupling agent is (80-100):(0.1-0.5):(3-5):(1-4).

8. The method for preparing the transparent super-hydrophobic peelable coating material according to any one of claims 1 to 7, characterized in that: The steps include: (1) adding an alkali solution, a silicon source, and a first silane coupling agent to an alcohol solvent, mixing them, and performing a hydrolysis reaction to obtain a transparent SiO2 dispersion; (2) adding a low surface energy modifier to the transparent SiO2 dispersion obtained in step (1), stirring and reacting, thereby obtaining a transparent super-hydrophobic SiO2-based topcoat; (3) adding hydrophilic particles, a second silane coupling agent, a defoamer, a wetting agent, and a film-forming agent to the water-based resin and stirring the mixture to obtain a transparent peeling primer; (4) coating the obtained transparent peeling primer on the surface of the substrate, and after the primer is dried, spraying the obtained transparent super-hydrophobic SiO2-based topcoat on the surface, and drying, thereby obtaining the transparent super-hydrophobic peelable composite coating.

9. The preparation method according to claim 8, characterized in that: The stirring reaction time in step (2) is 6 to 12 hours; the stirring time in step (3) is 0.5 to 1 hour.

10. The preparation method according to claim 8, characterized in that: The spraying process parameters of the transparent super-hydrophobic SiO2-based topcoat include: a spray gun caliber of 0.8 to 1.0 mm, an air pressure of 0.4 to 0.7 MPa; a spraying angle perpendicular to the substrate; a spraying distance of 25 to 30 cm; and a spray width of 10 to 15 cm.

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