A long-life super-hydrophobic composite coating and preparation method thereof

Abstract

The present invention provides a long-life super-hydrophobic composite coating and a preparation method thereof, belonging to the technical field of super-hydrophobic materials. The long-life super-hydrophobic composite coating of the present invention is composed of a bottom layer and a surface layer, wherein the bottom layer is composed of an aqueous single-component fluorocarbon resin and water-swellable polyurethane micron particles; the surface layer is composed of hydrophobically modified nano-silica, anhydrous ethanol and a silane coupling agent. The technical solution provided by the present invention has both the technical advantages of simple preparation process, low cost and wide applicable substrate range in the "top-down" method, and the technical advantages of stable micro-nanostructure state and outstanding wear resistance in the "bottom-up" method, so as to achieve the technical effect of long-life super-hydrophobicity.

Description

Technical Field

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

[0002] Wettability is one of the important properties of the surface of solid materials. The key factors that determine the wettability of the material surface include the chemical composition of the material surface and the microscopic geometric structure of the surface. In the industry, surfaces with a static water contact angle greater than 150° and a rolling angle less than 10° are called superhydrophobic surfaces. They have broad application prospects in self-cleaning, fluid drag reduction, lossless microfluidic transport, biotechnology and other fields.

[0003] Studies have shown that micro-nano composite structures and low surface energy are necessary conditions for forming super-hydrophobic structures. At present, there are two main methods for preparing super-hydrophobic surfaces: one is the "top-down" type, that is, constructing micro-nano surface structures on low surface energy surfaces, usually using chemical deposition methods, sol-gel methods, etc. This method has the advantages of rich raw material types, low cost, simple reaction conditions and equipment, and a wide range of applicable substrates. However, since it is difficult for the micro-nano structure to be firmly bonded to the substrate, it has poor wear resistance, especially in harsh environments such as outdoor rain erosion, and the super-hydrophobic effect is lost in as fast as a few hours.

[0004] The other type is the "bottom-up" type, which is to add a layer of low-surface-energy material to the surface of the micro-nano surface structure. Usually, laser etching, chemical corrosion and other methods are used to construct the micro-nano surface structure, and then a layer of low-surface-energy material is covered to achieve a super-hydrophobic effect. The main technical advantages of this method are that the micro-nano structure is stable and has outstanding wear resistance, so it has a long service life. However, this type of method is applicable to a narrow range of substrates. For example, laser etching is applicable to silicon wafers and metals, and chemical corrosion is applicable to metals. At the same time, this type of method often requires complex and expensive equipment and harsh environmental conditions, so it can only be used in some small-scale, high-value-added fields.

[0005] Therefore, in view of the problems of the prior art, how to obtain a super-hydrophobic coating with a simple preparation process, low cost, wide application range and wear resistance is a technical problem that needs to be solved at present. Summary of the invention

[0006] The object of the present invention is to provide a long-life super-hydrophobic composite coating and a preparation method thereof, so as to solve the technical problem that the existing super-hydrophobic materials cannot have both simple preparation process, low cost and outstanding wear resistance.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The invention provides a long-life super-hydrophobic composite coating, which consists of a bottom layer and a surface layer, wherein the bottom layer consists of a water-based single-component fluorocarbon resin and water-swellable polyurethane micron particles; and the surface layer consists of hydrophobically modified nano-silica, anhydrous ethanol and a silane coupling agent.

[0009] Furthermore, the volume ratio of the water-swellable polyurethane micron particles to the water-based single-component fluorocarbon resin is 30-60:40-70.

[0010] Furthermore, the volume water swelling rate of the water-swellable polyurethane micron particles is 2 to 4 times, and the average size of the micron particles is 30 to 60 μm.

[0011] Furthermore, the mass ratio of the hydrophobically modified nano-silica, anhydrous ethanol and silane coupling agent is 0.5-1.5:98-99:0.5-1.5.

[0012] Furthermore, the hydrophobically modified nano-silica is Wacker HDK H2000, and the silane coupling agent includes perfluorooctyltrimethoxysilane or perfluorodecyltrimethoxysilane.

[0013] Furthermore, the bottom layer is prepared from a bottom layer material, and the preparation method of the bottom layer material comprises the following steps:

[0014] 1) crushing the water-swellable polyurethane into particles of 30 to 60 microns;

[0015] 2) The above particles are placed in water to absorb water until they are fully expanded, and then dispersed in a water-based single-component fluorocarbon resin to obtain the base material.

[0016] Furthermore, the surface layer is prepared from a surface layer material, and the preparation method of the surface layer material comprises the following steps:

[0017] 1) dispersing the hydrophobically modified nano-silica in anhydrous ethanol to obtain a hydrophobically modified nano-silica ethanol dispersion;

[0018] 2) After mixing the hydrophobically modified nano-silica ethanol dispersion and the silane coupling agent, the surface layer material is obtained.

[0019] The present invention provides a method for preparing a long-life super-hydrophobic composite coating, comprising the following steps:

[0020] 1) coating the base material on the surface of the substrate, and performing a curing treatment after the surface is dry to obtain the base material;

[0021] 2) Spraying the surface layer material onto the surface of the bottom layer, and obtaining a long-life super-hydrophobic composite coating after curing.

[0022] Furthermore, in the step 1), the curing temperature is 120-140° C., and the curing time is 20-24 hours; and the substrate is a metal plate.

[0023] Furthermore, the spraying pressure is 0.5-0.8 MPa, the spraying width is 20 cm, and the number of spraying is 2-4 times.

[0024] Beneficial effects of the present invention:

[0025] The present invention proposes a long-life super-hydrophobic composite coating and a preparation method thereof, which has the technical advantages of a simple preparation process, low cost, and a wide range of applicable substrates in a "top-down" method, and also has the technical advantages of a stable micro-nano structure state and outstanding wear resistance in a "bottom-up" method, so as to achieve the technical effect of long-life super-hydrophobicity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a contact angle test photo of Example 1 of the present invention after the water impact resistance test;

[0027] Figure 2 This is a contact angle test photo of Example 2 of the present invention after the water impact resistance test;

[0028] Figure 3 This is a contact angle test photo of Example 3 of the present invention after the water impact resistance test;

[0029] Figure 4 This is a contact angle test photo of Comparative Example 1 after the water flushing resistance test;

[0030] Figure 5 This is a contact angle test photo of comparative example 2 after water flushing resistance test;

[0031] Figure 6 This is a photograph of the appearance of Example 1 of the present invention after water washing, wherein the circle is the water washing position;

[0032] Figure 7 This is a photograph of the appearance of Example 2 of the present invention after water washing resistance, wherein the circle is the water washing position;

[0033] Figure 8 This is a photograph of the appearance of Example 3 of the present invention after water washing, wherein the circle is the water washing position;

[0034] Fig. 9 This is a photo of the surface of Comparative Example 1 after water flushing, where the circle is the water flushing position;

[0035] Fig.10 This is a photograph of the appearance of Comparative Example 2 after water flushing, where the circle is the water flushing position. DETAILED DESCRIPTION

[0036] The invention provides a long-life super-hydrophobic composite coating, which consists of a bottom layer and a surface layer, wherein the bottom layer consists of a water-based single-component fluorocarbon resin and water-swellable polyurethane micron particles; and the surface layer consists of hydrophobically modified nano-silica, anhydrous ethanol and a silane coupling agent.

[0037] In the present invention, the volume ratio of the water-swellable polyurethane microparticles to the water-based single-component fluorocarbon resin is 30-60:40-70, preferably 30:70, 40:60, 50:50 or 60:40.

[0038] In the present invention, the water-based one-component fluorocarbon resin is 101 water-based one-component fluorocarbon emulsion produced by Shanghai Fluorochemical Co., Ltd.

[0039] In the present invention, the volume water swelling rate of the water-swellable polyurethane microparticles is 2 to 4 times, preferably 3 times; the average size of the microparticles is 30 to 60 μm, preferably 35 to 55 μm, and more preferably 40 to 50 μm.

[0040] In the present invention, the mass ratio of the hydrophobically modified nano-silica, anhydrous ethanol and silane coupling agent is 0.5-1.5:98-99:0.5-1.5, preferably 1:99:1.

[0041] In the present invention, the hydrophobically modified nano-silica is preferably Wacker HDK H2000, and the silane coupling agent comprises perfluorooctyltrimethoxysilane or perfluorodecyltrimethoxysilane, preferably perfluorooctyltrimethoxysilane.

[0042] In the present invention, the bottom layer is prepared from a bottom layer material, and the preparation method of the bottom layer material comprises the following steps:

[0043] 1) crushing the water-swellable polyurethane into particles of 30 to 60 microns;

[0044] 2) The above particles are placed in water to absorb water until they are fully expanded, and then dispersed in a water-based single-component fluorocarbon resin to obtain the base material.

[0045] In the present invention, the surface layer is prepared from a surface layer material, and the preparation method of the surface layer material comprises the following steps:

[0046] 1) dispersing the hydrophobically modified nano-silica in anhydrous ethanol to obtain a hydrophobically modified nano-silica ethanol dispersion;

[0047] 2) After mixing the hydrophobically modified nano-silica ethanol dispersion and the silane coupling agent, the surface layer material is obtained.

[0048] The present invention provides a method for preparing a long-life super-hydrophobic composite coating, comprising the following steps:

[0049] 1) coating the base material on the surface of the substrate, and performing a curing treatment after the surface is dry to obtain the base material;

[0050] 2) Spraying the surface layer material onto the surface of the bottom layer, and obtaining a long-life super-hydrophobic composite coating after curing.

[0051] In the present invention, the wet film thickness of the base layer is 100 to 200 μm, preferably 120 to 180 μm, and more preferably 150 μm.

[0052] In the present invention, in the step 1), the curing temperature is 120-140°C, preferably 125-135°C, and more preferably 130°C; the curing time is 20-24h, preferably 24h; and the substrate is a metal plate, preferably an aluminum plate.

[0053] In the present invention, the spraying pressure is 0.5-0.8 MPa, preferably 0.6 MPa; the spray width is 20 cm; the number of spraying is 2-4 times, preferably 3 times.

[0054] In the present invention, in step 2), curing is performed at room temperature for 6 to 8 days, preferably 7 days.

[0055] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0056] Example 1

[0057] A commercially available water-swellable polyurethane specimen with a volume water-swelling ratio of 4 times was used, and it was crushed into particles with an average size of 30 μm by a low-temperature freezing crushing method, and then put into clean water to absorb water saturatedly until it was fully expanded, and the water-swellable polyurethane micron particles: aqueous single-component fluorocarbon resin (volume ratio) were mixed evenly at a ratio of 30:70 to obtain a base material; hydrophobically modified nano-silica was added to anhydrous ethanol and ultrasonically dispersed for 30 minutes to obtain a hydrophobically modified nano-silica ethanol dispersion; the above dispersion was cooled to room temperature, and perfluorooctyltrimethoxysilane was added and stirred evenly to obtain a surface material, wherein the mass ratio of hydrophobically modified nano-silica, anhydrous ethanol and perfluorooctyltrimethoxysilane was 1:99:1.

[0058] The above-mentioned base material was brushed on the surface of the aluminum plate, and the wet film thickness was controlled to be 100 μm using a wet film thickness gauge. After the surface was dry, it was placed in a 120°C oven for curing for 24 hours, and then placed at room temperature for 12 hours.

[0059] The surface material was air-sprayed onto the cured surface of the base layer using an Iwata 1.5 mm caliber spray gun. The spraying pressure was 0.6 MPa, the spray width was 20 cm, the number of spraying times was 2 times, and a long-life super-hydrophobic composite coating was obtained after curing at room temperature for 7 days.

[0060] The long-life super-hydrophobic composite coating was tested by using a contact angle tester for initial contact angle, initial rolling angle, contact angle after water flushing test, rolling angle after water flushing test, contact angle after aging test, and rolling angle after aging test. The results are shown in Table 1. Figure 1 and Figure 6 .

[0061] The water impact resistance test refers to the use of 0.2MPa water pressure and a vertical water flow at a distance of 10cm from the coating surface to impact the coating surface, and the test time is 6min.

[0062] The aging test refers to the xenon lamp aging test for 1000 hours using method 1 that meets GB / T 1865.

[0063] Example 2

[0064] A commercially available water-swelling polyurethane specimen with a volume water-swelling ratio of 2 times was used, and was crushed into particles with an average size of 60 μm by a low-temperature freezing crushing method. The particles were placed in clean water to absorb water until they were fully expanded, and the water-swelling polyurethane micron particles and aqueous single-component fluorocarbon resin (volume ratio) were mixed evenly at a ratio of 60:40 to obtain a base material; hydrophobically modified nano-silica was added to anhydrous ethanol and ultrasonically dispersed for 30 minutes to obtain a hydrophobically modified nano-silica ethanol dispersion; the above dispersion was cooled to room temperature, and perfluorooctyltrimethoxysilane was added and stirred evenly to obtain a surface material, wherein the mass ratio of hydrophobically modified nano-silica, anhydrous ethanol and perfluorooctyltrimethoxysilane was 1:99:1.

[0065] The above-mentioned base material was brushed on the surface of the aluminum plate, and the wet film thickness was controlled to be 200 μm using a wet film thickness gauge. After the surface was dry, it was placed in a 140°C oven for curing for 24 hours, and then placed at room temperature for 12 hours.

[0066] The surface material was air-sprayed onto the cured surface of the base layer using an Iwata 1.5 mm caliber spray gun. The spraying pressure was 0.6 MPa, the spray width was 20 cm, the number of spraying times was 4, and a long-life super-hydrophobic composite coating was obtained after curing at room temperature for 7 days.

[0067] The long-life super-hydrophobic composite coating was tested by using a contact angle tester for initial contact angle, initial rolling angle, contact angle after water flushing test, rolling angle after water flushing test, contact angle after aging test, and rolling angle after aging test. The results are shown in Table 1. Figure 2and Figure 7 .

[0068] Example 3

[0069] A commercially available water-swelling polyurethane specimen with a volume water-swelling ratio of 2 times was used, and was crushed into particles with an average size of 40 μm by a low-temperature freezing crushing method. The particles were placed in clean water for saturated water absorption until they were fully expanded, and the water-swelling polyurethane micron particles and aqueous single-component fluorocarbon resin (volume ratio) were mixed evenly at a ratio of 50:50 to obtain a base material; hydrophobically modified nano-silica was added to anhydrous ethanol and ultrasonically dispersed for 30 minutes to obtain a hydrophobically modified nano-silica ethanol dispersion; the above dispersion was cooled to room temperature, and perfluorodecyltrimethoxysilane was added and stirred evenly to obtain a surface material, wherein the mass ratio of hydrophobically modified nano-silica, anhydrous ethanol and perfluorodecyltrimethoxysilane was 1:99:1.

[0070] The above-mentioned base material was brushed on the surface of the aluminum plate, and the wet film thickness was controlled to be 140 μm using a wet film thickness gauge. After the surface was dry, it was placed in a 140°C oven for curing for 24 hours, and then taken out and placed at room temperature for 12 hours.

[0071] The surface material was air-sprayed onto the cured surface of the base layer using an Iwata 1.5 mm caliber spray gun. The spraying pressure was 0.6 MPa, the spray width was 20 cm, the number of spraying times was 3, and a long-life super-hydrophobic composite coating was obtained after curing at room temperature for 7 days.

[0072] The long-life super-hydrophobic composite coating was tested by using a contact angle tester for initial contact angle, initial rolling angle, contact angle after water flushing test, rolling angle after water flushing test, contact angle after aging test, and rolling angle after aging test. The results are shown in Table 1. Figure 3 and Figure 8 .

[0073] Comparative Example 1

[0074] The same as Example 1, except that an aqueous single-component fluorocarbon resin is directly used as the base material; hydrophobically modified nano-silica is added to anhydrous ethanol and ultrasonically dispersed for 30 minutes to obtain a hydrophobically modified nano-silica ethanol dispersion; the above dispersion is cooled to room temperature, and perfluorooctyltrimethoxysilane is added and stirred evenly to obtain a surface layer material, wherein the mass ratio of hydrophobically modified nano-silica, anhydrous ethanol and perfluorooctyltrimethoxysilane is 1:99:1.

[0075] The above-mentioned base material was brushed on the surface of the aluminum plate, and the wet film thickness was controlled to be 100 μm using a wet film thickness gauge. After the surface was dry, it was placed in a 120°C oven for curing for 24 hours, and then placed at room temperature for 12 hours.

[0076] The surface material was air-sprayed onto the cured surface of the base layer using an Iwata 1.5 mm caliber spray gun. The spraying pressure was 0.6 MPa, the spray width was 20 cm, the number of spraying times was 2 times, and a long-life super-hydrophobic composite coating was obtained after curing at room temperature for 7 days.

[0077] The long-life super-hydrophobic composite coating was tested by using a contact angle tester for initial contact angle, initial rolling angle, contact angle after water flushing test, rolling angle after water flushing test, contact angle after aging test, and rolling angle after aging test. The results are shown in Table 1. Figure 4 and Fig. 9 .

[0078] Comparative Example 2

[0079] The same as Example 1, except that commercially available polyurethane strips without water absorption and swelling function are used, and the strips are crushed into particles with an average size of 30 μm by a low-temperature freezing crushing method, and the polyurethane micron particles: aqueous single-component fluorocarbon resin (volume ratio) are evenly mixed at a ratio of 30:70 to obtain a base material; hydrophobically modified nano-silica is added to anhydrous ethanol, ultrasonically dispersed for 30 minutes, to obtain a hydrophobically modified nano-silica ethanol dispersion, the above dispersion is cooled to room temperature, and perfluorooctyltrimethoxysilane is added and stirred evenly to obtain a surface material, wherein the mass ratio of hydrophobically modified nano-silica, anhydrous ethanol and perfluorooctyltrimethoxysilane is 1:99:1.

[0080] The above-mentioned base material was brushed on the surface of the aluminum plate, and the wet film thickness was controlled to be 100 μm using a wet film thickness gauge. After the surface was dry, it was placed in a 120°C oven for curing for 24 hours, and then placed at room temperature for 12 hours.

[0081] The surface material was air-sprayed onto the cured surface of the base layer using an Iwata 1.5 mm caliber spray gun. The spraying pressure was 0.6 MPa, the spray width was 20 cm, the number of spraying times was 2 times, and a long-life super-hydrophobic composite coating was obtained after curing at room temperature for 7 days.

[0082] The long-life super-hydrophobic composite coating was tested by using a contact angle tester for initial contact angle, initial rolling angle, contact angle after water flushing test, rolling angle after water flushing test, contact angle after aging test, and rolling angle after aging test. The results are shown in Table 1. Figure 5 and Fig.10 .

[0083] Table 1 Test results of embodiments and comparative examples

[0084]

[0085]

[0086] As can be seen from the above embodiments, the present invention provides a long-life super-hydrophobic composite coating and a preparation method thereof. As can be seen from Table 1 above, after water flushing and aging tests, the contact angle of Examples 1 to 3 is basically not reduced, the rolling angle is slightly increased, but the super-hydrophobic state is still maintained, showing good water flushing resistance and aging resistance, while in Comparative Examples 1 and 2, the rolling angle is significantly increased after water flushing, so that the super-hydrophobic effect is lost, which also shows that the material system design in the present invention is indispensable.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A long-life super-hydrophobic composite coating, characterized in that: The long-life super-hydrophobic composite coating consists of a bottom layer and a surface layer, wherein the bottom layer consists of a water-based single-component fluorocarbon resin and water-swellable polyurethane micron particles; and the surface layer consists of hydrophobically modified nano-silica, anhydrous ethanol and a silane coupling agent.

2. The long-life super-hydrophobic composite coating according to claim 1, characterized in that: The volume ratio of the water-swellable polyurethane micron particles to the water-based single-component fluorocarbon resin is 30-60:40-70.

3. The long-life super-hydrophobic composite coating according to claim 1 or 2, characterized in that: The volume water swelling rate of the water-swellable polyurethane micron particles is 2 to 4 times, and the average size of the micron particles is 30 to 60 μm.

4. The long-life super-hydrophobic composite coating according to claim 3, characterized in that: The mass ratio of the hydrophobically modified nano-silica, anhydrous ethanol and silane coupling agent is 0.5-1.5:98-99:0.5-1.

5.

5. The long-life super-hydrophobic composite coating according to claim 1 or 4, characterized in that: The hydrophobically modified nano-silica is Wacker HDK H2000, and the silane coupling agent includes perfluorooctyltrimethoxysilane or perfluorodecyltrimethoxysilane.

6. The long-life super-hydrophobic composite coating according to claim 1, 2 or 4, characterized in that: The bottom layer is prepared from a bottom layer material, and the preparation method of the bottom layer material comprises the following steps: 1) crushing the water-swellable polyurethane into particles of 30 to 60 microns; 2) The above particles are placed in water to absorb water until they are fully expanded, and then dispersed in a water-based single-component fluorocarbon resin to obtain the base material.

7. The long-life super-hydrophobic composite coating according to claim 6, characterized in that: The surface layer is prepared from a surface layer material, and the preparation method of the surface layer material comprises the following steps: 1) dispersing the hydrophobically modified nano-silica in anhydrous ethanol to obtain a hydrophobically modified nano-silica ethanol dispersion; 2) After mixing the hydrophobically modified nano-silica ethanol dispersion and the silane coupling agent, the surface layer material is obtained.

8. The method for preparing the long-life super-hydrophobic composite coating according to claim 7, characterized in that: The steps include: 1) coating the base material on the surface of the substrate, and performing a curing treatment after the surface is dry to obtain the base material; 2) Spraying the surface layer material onto the surface of the bottom layer, and obtaining a long-life super-hydrophobic composite coating after curing.

9. The method for preparing a long-life super-hydrophobic composite coating according to claim 8, characterized in that: In the step 1), the curing temperature is 120-140° C., and the curing time is 20-24 hours; and the substrate is a metal plate.

10. The method for preparing a long-life super-hydrophobic composite coating according to claim 8 or 9, characterized in that: The spraying pressure is 0.5-0.8 MPa, the spray width is 20 cm, and the number of spraying is 2-4 times.

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