A hydrophobic membrane and its preparation method

Abstract

The present invention relates to a hydrophobic film and a preparation method thereof. The preparation method includes the following steps: (1) After etching a glass sheet with hydrofluoric acid and heating, a substrate is obtained; (2) A fuel and silicone are mixed and sprayed on the surface of the substrate obtained in step (1) to form a mixed layer; (3) The substrate obtained in step (2) is heat-treated; (4) A hydrophobic agent is deposited on the substrate obtained in step (3) to obtain the hydrophobic film. The preparation method provided by the present invention has simple process operation, can be prepared in a large area, improves the service life problem during the application of the hydrophobic film. When there are pollutants on the superhydrophobic surface, they will also be removed by rolling water droplets, enabling the surface to have a self-cleaning effect at the same time, and is applicable to the glass cover plates in the photovoltaic industry.

Description

Technical Field

[0001] The present invention relates to the technical field of membrane materials, and particularly to a hydrophobic membrane and a preparation method thereof. Background Art

[0002] Hydrophobic surfaces have always faced challenges in practical applications and preparations. There are problems such as mechanical stability and lifespan in terms of performance, and in terms of processes, there are problems such as high cost, complex processes, and restricted large-area preparation in constructing micro-nano structures.

[0003] Most artificially prepared superhydrophobic surfaces are carried out at low and normal temperatures. The film layer cannot bond with the substrate. When subjected to mechanical actions such as friction and impact, the surface structure will be damaged and lose its hydrophobicity, and the lifespan of the hydrophobic surface is very short. Therefore, developing a hydrophobic coating surface with stable impact or wear resistance is the key to promoting the real practical application of hydrophobic materials.

[0004] Therefore, in view of the above deficiencies, it is necessary to provide a hydrophobic membrane with better effects. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the surface structure of the existing hydrophobic membrane is not strong enough in stability and not high in impact resistance. The present invention provides a hydrophobic membrane and a preparation method thereof to achieve the effects of stronger anti-flushing performance and better stability.

[0006] To solve the above technical problem, the present invention provides a preparation method of a hydrophobic membrane, and the preparation method includes the following steps:

[0007] (1) After etching and heating a glass sheet with hydrofluoric acid, a substrate is obtained;

[0008] (2) Mix a fuel and silicone, and spray it on the surface of the substrate obtained in step (1) to form a mixed layer;

[0009] (3) Heat-treat the substrate obtained in step (2);

[0010] (4) Deposit a hydrophobic agent on the substrate obtained in step (3) to obtain the hydrophobic membrane.

[0011] Adopt a method similar to flame spraying to deposit a C-SiO 2 mixed layer on the surface of high-temperature glass. After heat treatment below the softening point, deposit a hydrophobic agent again, thereby preparing a strong hydrophobic membrane layer.

[0012] The preparation method provided by the present invention first cleans the glass surface and corrodes it with hydrofluoric acid, then performs heat treatment at a temperature lower than the softening point to maintain a high temperature on the surface without deformation. Then, the raw materials are ignited and sprayed on the glass surface. Under the action of instant high temperature, the formed silicon dioxide nanoparticles decompose and form welding points with the glass surface, strengthening the bonding force between the film layer and the glass. Among them, incompletely burned carbon nanoparticles are mixed, and after heat treatment, a porous silicon dioxide nanoparticle layer is formed, and a superhydrophobic film is formed after the deposition of a hydrophobic agent.

[0013] The hydrophobic film is formed on the surface of the glass substrate. Under the action of instant high temperature, the silicon dioxide crystals on the glass substrate surface are welded to the glass, having a strong bonding force and certain water impact resistance properties. When there are pollutants on the superhydrophobic surface, they will also be removed by rolling water droplets, enabling the surface to have a self-cleaning effect at the same time, and it is applicable to the glass cover plates in the photovoltaic industry.

[0014] Preferably, in step (1), the softening point of the glass sheet is higher than 750 °C;

[0015] Preferably, in step (1), the glass sheet includes any one of borosilicate glass sheets, aluminosilicate glass sheets, or quartz glass.

[0016] Preferably, in step (1), the heating temperature is 650 - 750 °C, for example, it can be 650 °C, 670 °C, 690 °C, 700 °C, 720 °C, or 750 °C, etc.

[0017] Preferably, in step (2), the fuel includes any one or a combination of at least two of gasoline, diesel, grease, or paraffin.

[0018] In the present invention, the fuel can also be a fuel with a carbon chain length > 5 such as alkanes. The pressure of the flame spraying is appropriately adjusted according to the carbon chain length to ensure that there is both co-deposition of carbon and silicon oxide without complete combustion and that the flame has a temperature higher than 700 °C.

[0019] Preferably, in step (2), the organosilicon is a compound that can be decomposed by heating to produce silicon dioxide;

[0020] Preferably, the organosilicon includes any one of tetraethyl orthosilicate, trimethoxysilane, or triethylsilane.

[0021] In step (2) of the present invention, the spraying process can specifically be to put the raw materials into a blowtorch and then ignite to form a mixed layer on the high-temperature glass surface; or use a liquid fuel spray gun to form a mixed film layer on the glass surface.

[0022] Preferably, the volume ratio of the silicone to the fuel in step (2) is 1:(1~10), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, etc.

[0023] In the present invention, by controlling the volume ratio within this range, it can not only ensure the ejection of flame, but also decompose the silicone under the action of the high temperature of the flame to form a C-SiO 2 layer on the surface. If the ratio is greater than 1 / 1, excessive silicone will cause the formed SiO 2 to block the muzzle or no flame will be generated at all; if it is less than 1 / 10, the carbon / SiO 2 ratio in the formed film layer is too large, and a hydrophobic structure cannot be formed.

[0024] Preferably, the heat treatment in step (3) is to heat the substrate in a high-temperature device. The high-temperature device of the present invention can be an electric furnace, etc.

[0025] Preferably, the temperature of the heat treatment is 650~750°C, for example, it can be 650°C, 670°C, 700°C, 720°C or 750°C, etc. In the present invention, if the temperature of the heat treatment is too high, the glass surface will soften and distort; if it is too low, the film layer and the glass substrate cannot form a welding point and are likely to fall off.

[0026] Preferably, the time of the heat treatment is 0.5~4h, for example, it can be 0.5h, 1h, 2h, 3h or 4h, etc.

[0027] Preferably, the deposition in step (4) is carried out under the condition of a vacuum degree of -0.06MPa to -0.1MPa. This vacuum degree can be formed by a vacuum dryer or other devices that can provide a negative pressure environment. The vacuum degree can be -0.06MPa, -0.07MPa, -0.08MPa, -0.09MPa or -0.1MPa, etc.

[0028] Preferably, the time of the deposition in step (4) is 0.5~1.5h.

[0029] Preferably, the hydrophobic agent in step (4) includes any one or a combination of at least two of perfluorooctyltriethoxysilane, perfluorodecyltriethoxysilane, perfluorooctyltrichlorosilane, (3,3,3-trifluoropropyl)methyldimethoxysilane, trifluoromethyltrimethylsilane, trifluoropropylmethyldichlorosilane or nonafluorohexyltrimethoxysilane; preferably any one or a combination of at least two of perfluorooctyltriethoxysilane, perfluorodecyltriethoxysilane or perfluorooctyltrichlorosilane. In the present invention, the above hydrophobic agents are preferably used, and the prepared hydrophobic film has better performance.

[0030] On the other hand, the present invention provides a hydrophobic film prepared by the preparation method as described above.

[0031] Implementing the method of the present invention has the following beneficial effects:

[0032] In the preparation method provided by the present invention, the glass surface is first cleaned and etched with hydrofluoric acid, and then heat-treated at a temperature below the softening point to maintain a high temperature on the surface without deformation. Then, the raw materials are ignited and sprayed on the glass surface. Under the action of instant high temperature, the formed silicon dioxide nanoparticles decompose and form welding points with the glass surface, strengthening the bonding force between the film layer and the glass; among them, there are incompletely burned carbon nanoparticles, which form a porous silicon dioxide nanoparticle layer after heat treatment, and form a superhydrophobic film after the deposition of a hydrophobic agent.

[0033] The hydrophobic film is formed on the surface of the glass substrate. The silicon dioxide crystals are welded to the glass under the action of instant high temperature on the surface of the glass substrate, having a strong bonding force and certain water impact resistance properties, improving the service life problem during the application of the hydrophobic film. When there are pollutants on the superhydrophobic surface, they will also be removed by rolling water droplets, enabling the surface to have a self-cleaning effect at the same time, and is applicable to the glass cover plates in the photovoltaic industry. Description of the Drawings

[0034] Figure 1 It is a test result diagram of the contact angle of the glass surface obtained in Example 1 of the present invention.

[0035] Figure 2 It is a hydrophobicity diagram of the glass surface obtained in Example 1 of the present invention.

[0036] Figure 3 It is a scanning electron microscope diagram of the glass surface obtained in Example 1 of the present invention, magnified 20,000 times, and the scale is 500 nm. Detailed Embodiments

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Example 1

[0038] This example prepares a hydrophobic film through the following steps

[0039] (1) Clean the borosilicate glass sheet, etch it with 15% hydrofluoric acid for 10 minutes, and then put it into an electric furnace and heat it to 700 °C;

[0040] (2) Mix tetraethyl orthosilicate and n - hexadecane in a volume ratio of 1:5 as raw materials. Add the raw materials into a diesel burner, ignite and spray them on the glass surface to form a C - SiO 2 mixed layer;

[0041] (3) Quickly put the glass sheet with the C - SiO 2 film layer back into the electric furnace for heat treatment at 700 °C for 0.5 h;

[0042] (4) Put 1H,1H,2H,2H - perfluorooctyltriethoxysilane and the glass substrate in step (3) into a vacuum dryer, control the vacuum degree at - 0.08 MPa for 1 h to prepare a hydrophobic film.

[0043] As Figure 1 shown, for the glass sample prepared by the preparation method of Example 1, test the hydrophobicity. The surface shows super - hydrophobicity, and the hydrophobic property remains unchanged after the impact of water flow (0.1 - 0.3 MPa). Figure 2 is the hydrophobicity diagram of the prepared glass surface. Figure 3 is the scanning electron microscope image of the prepared glass surface. Example 2

[0044] This example prepares a hydrophobic film through the following steps

[0045] (1) Clean the borosilicate glass sheet, etch it with 15% hydrofluoric acid for 10 min, and then put it into an electric furnace and heat it to 700 °C;

[0046] (2) Mix tetraethyl orthosilicate and diesel in a volume ratio of 1:5 as raw materials. Add the raw materials into a diesel burner, ignite and spray them on the glass surface to form a C - SiO 2 mixed layer;

[0047] (3) Quickly put the glass sheet with the C - SiO 2 film layer back into the electric furnace for heat treatment at 700 °C for 0.5 h;

[0048] (4) Put 1H,1H,2H,2H - perfluorooctyltriethoxysilane and the glass substrate in step (3) into a vacuum dryer, control the vacuum degree at - 0.08 MPa for 1 h to prepare a hydrophobic film.

[0049] For the glass sample prepared by the preparation method of Example 2, test the hydrophobicity. The surface shows super - hydrophobicity, and the hydrophobic property remains unchanged after the impact of water flow (0.1 - 0.3 MPa). Example 3

[0050] This example prepares a hydrophobic film through the following steps

[0051] (1) Clean the borosilicate glass sheet. After etching with 15% hydrofluoric acid for 10 min, place it in an electric furnace and heat it to 720 °C.

[0052] (2) Mix tetraethyl orthosilicate and undecane in a volume ratio of 1:8 as raw materials. Add the raw materials to a diesel burner, ignite and spray them on the glass surface to form a C-SiO 2 mixed layer;

[0053] (3) Quickly place the glass sheet with the C-SiO 2 film layer back into the electric furnace and heat-treat it at 720 °C for 0.5 h;

[0054] (4) Place 1H,1H,2H,2H-perfluorooctyltriethoxysilane and the glass substrate from step (3) together in a vacuum dryer. Control the vacuum degree at -0.08 MPa for 1 h to prepare a hydrophobic film.

[0055] For the glass sample prepared by the preparation method of Example 3, test the hydrophobicity. The surface shows superhydrophobicity, and the hydrophobic property remains unchanged after the impact of water flow (0.1 - 0.3 MPa). Example 4

[0056] This example prepares a hydrophobic film through the following steps

[0057] (1) Clean the quartz glass sheet. After etching with 15% hydrofluoric acid for 10 min, place it in an electric furnace and heat it to 700 °C;

[0058] (2) Mix tetraethyl orthosilicate and undecane in a volume ratio of 1:8 as raw materials. Add the raw materials to a diesel burner, ignite and spray them on the glass surface to form a C-SiO 2 mixed layer;

[0059] (3) Quickly place the glass sheet with the C-SiO 2 film layer back into the electric furnace and heat-treat it at 700 °C for 0.5 h;

[0060] (4) Place 1H,1H,2H,2H-perfluorooctyltriethoxysilane and the glass substrate from step (3) together in a vacuum dryer. Control the vacuum degree at -0.08 MPa for 1 h to prepare a hydrophobic film.

[0061] For the glass sample prepared by the preparation method of Example 4, test the hydrophobicity. The surface shows superhydrophobicity, and the hydrophobic property remains unchanged after the impact of water flow (0.1 - 0.3 MPa). Example 5

[0062] This example is basically the same as Example 2, but the heat treatment temperature is changed to 500 °C. The obtained film layer has superhydrophobic properties, but when impacted by water flow, the film layer peels off. Example 6

[0063] The operations of cleaning and film deposition in steps (1) and (2) of Example 2 are the same, but ordinary soda-lime-silica glass is used as the substrate, and the heat treatment temperature is adjusted to 620 °C (since the softening point of soda-lime-silica glass is low, too high a temperature will cause surface softening and deformation). The obtained film has superhydrophobic properties, but the film still peels off when impacted by water flow. Example 7

[0064] This example is the same as steps (1), (3), and (4) of Example 2, and in step (2), the ratio of TEOS to diesel is adjusted to 2:1. Because the content of silicone is high and the fuel content is low, the muzzle becomes blocked after ignition and continuous combustion cannot be achieved, so spraying cannot be completed.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that this comparative example does not include step (3) and directly proceeds to step (4) to obtain a hydrophobic film.

[0067] Experimental result: The prepared sample does not have superhydrophobic properties.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that this comparative example does not include step (2) for preparing the hydrophobic film.

[0070] Experimental result: During the preparation process, a loose and porous film layer cannot be formed on the glass surface, and the hydrophobic film fails to achieve the hydrophobic effect.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 is that in this comparative example, spraying is not performed in step (2), but a SiO 2 gel film is formed on the glass surface by the sol-gel method.

[0073] Experimental result: The film layer has superhydrophobic properties, but the film layer has weak adhesion and is prone to peeling off after friction, so it has no practical value.

[0074] From the comparison of the experimental data of the above examples and comparative examples, it can be seen that the product prepared by the preparation process provided by the present invention has good stability, and once the preparation process is changed, the performance of the prepared hydrophobic film will decline.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a hydrophobic membrane, characterized in that, the preparation method comprises the following steps: (1) After etching and heating a glass sheet with hydrofluoric acid, a substrate is obtained; (2) Mix a fuel with silicone, and spray it on the surface of the substrate obtained in step (1) to form a mixed layer; (3) Heat-treat the substrate obtained in step (2); (4) Deposit a hydrophobic agent on the substrate obtained in step (3) to obtain the hydrophobic membrane; In step (1), the softening point of the glass sheet is higher than 750 °C; In step (2), the fuel includes any one or a combination of at least two of gasoline, diesel, grease or paraffin; the silicone includes any one of tetraethyl orthosilicate, trimethoxysilane or triethylsilane; in step (2), the volume ratio of the silicone to the fuel is 1:(1~10); The spraying process in step (2) is to put the fuel and silicone into a blowtorch, and then ignite to form a mixed layer on the surface of the high-temperature glass; or use a liquid fuel spray gun to form a mixed film layer on the glass surface; In step (3), the heat treatment is to heat the substrate in a high-temperature device; the temperature of the heat treatment is 700~750 °C; the time of the heat treatment is 0.5~4 h.

2. The preparation method according to claim 1, characterized in that, in step (1), the glass sheet includes any one of borosilicate glass sheet, aluminosilicate glass sheet or quartz glass.

3. The preparation method according to claim 1, characterized in that, in step (1), the heating temperature is 650~750 °C.

4. The preparation method according to claim 1, characterized in that, in step (4), the deposition is carried out under the condition of a vacuum degree of -0.06 MPa to -0.1 MPa.

5. The preparation method according to claim 1, characterized in that, in step (4), the deposition time is 0.5~1.5 h.

6. The preparation method according to claim 1, characterized in that, in step (4), the hydrophobic agent includes any one or a combination of at least two of perfluorooctyltriethoxysilane, perfluorodecyltriethoxysilane, perfluorooctyltrichlorosilane, (3,3,3-trifluoropropyl)methyldimethoxysilane, trifluoromethyltrimethylsilane, trifluoropropylmethyldichlorosilane or nonafluorohexyltrimethoxysilane.

7. The preparation method according to claim 6, characterized in that, in step (4), the hydrophobic agent is any one or a combination of at least two of perfluorooctyltriethoxysilane, perfluorodecyltriethoxysilane or perfluorooctyltrichlorosilane.

8. A hydrophobic membrane prepared by the preparation method according to any one of claims 1-7.

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