A method for preparing a polyurea photothermal anti-icing coating

Abstract

The application discloses a preparation method of a polyurea photo-thermal anti-icing coating and belongs to the technical field of photo-thermal anti-icing. The application is based on silica / polyurea composite particles and carbon materials, and super-hydrophobicity and relatively high photo-thermal conversion efficiency are obtained. The method is characterized in that silica nanoparticles are combined into polyurea molecules to form silica / polyurea composite particles; then the composite particles are combined with graphite microparticles and uniformly dispersed in polysiloxane, and a super-hydrophobic photo-thermal coating with excellent wear resistance and durability is developed. The coating surface has high photo-thermal conversion efficiency, can obviously increase temperature under the irradiation of sunlight, can delay the icing time and reduce the ice adhesion strength, and thus better anti-icing and de-icing effects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of photothermal anti-icing. Specifically, it relates to the preparation of a polyurea photothermal anti-icing coating. Background Technology

[0002] Icing on outdoor infrastructure and equipment surfaces can cause economic losses and safety hazards. Traditional anti-icing and de-icing methods, such as mechanical de-icing, chemical de-icing, thermal melting, and robotic de-icing, have drawbacks such as dangerous and complex operation, low efficiency, high consumption, and environmental pollution. Superhydrophobic coatings introduce micro- and nanoparticles into low surface energy materials to create a rough surface, preventing ice accumulation by slowing down the icing process and reducing the adhesion between ice and the surface. This method has some anti-icing performance, but its anti-icing ability is limited and its durability is usually insufficient, making it a passive anti-icing mode.

[0003] Introducing photothermal conversion materials (such as carbon materials) into superhydrophobic coatings can convert solar energy into thermal energy, thereby delaying icing or melting. Superhydrophobic photothermal coatings overcome the limitations of traditional passive anti-icing materials, representing an active anti-icing approach. However, these photothermal coatings can still ic up under low temperature or low light conditions, and their wear resistance and durability are also low due to material degradation during the de-icing process.

[0004] Therefore, preparing a superhydrophobic photothermal coating with high photothermal conversion efficiency, excellent mechanical properties, high durability, low cost, and the ability to meet the requirements of anti-icing and de-icing performance under weak sunlight conditions is an urgent problem to be solved in this field. Summary of the Invention

[0005] This invention aims to address the problems of poor wear resistance and insufficient anti-icing effect of existing superhydrophobic photothermal anti-icing coatings under weak sunlight conditions. It provides a method for preparing a polyurea superhydrophobic photothermal coating that improves mechanical properties while meeting the requirements for anti-icing and de-icing performance under weak sunlight conditions, mainly comprising the following steps:

[0006] S1. Synthesis of silica / polyurea composite microparticles:

[0007] The first batch of silica sol and polyurea resin were mixed in acetone solvent and stirred at a constant temperature of 30°C; then diisocyanate prepolymer and the second batch of silica sol were added in sequence; after high-speed centrifugation, washing, drying and grinding, silica / polyurea composite microparticles were obtained.

[0008] S2. Preparation of polyurea photothermal coating:

[0009] The silica / polyurea composite microparticles obtained in S1 were mixed and dispersed with graphite micron particles in ethyl acetate to obtain a uniformly dispersed silica / polyurea / graphite suspension.

[0010] PDMS was dissolved in n-hexane and then coated onto a clean glass substrate. After being left at room temperature for 30-60 minutes, two layers of silica / polyurea / graphite suspension were coated and cured at 60°C to obtain a polyurea photothermal coating.

[0011] S3. Surface hydrophobication treatment of polyurea photothermal coating:

[0012] A hydrophobic modified solution was obtained by uniformly mixing fluoroalkylsilane and n-hexane.

[0013] A hydrophobic modification liquid was coated on the surface of the polyurea photothermal coating obtained in S2 and dried at 60°C to obtain a polyurea photothermal anti-icing coating.

[0014] Further, the diisocyanate prepolymer described in S1 is one or more of isoflurane diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0015] Furthermore, the polyurea resin described in S1 is an aspartic aliphatic polyurea resin.

[0016] Furthermore, the mass ratio of the first batch of silica sol to the second batch of silica sol in S1 is 1:1; the total amount of the first and second batches of silica sol to the mass ratio of polyurea resin is 2:1 to 20:1; and the mass ratio of diisocyanate prepolymer to polyurea resin is 1:1 to 5:1.

[0017] Furthermore, the mass ratio of PDMS to n-hexane in S2 is 1:50 to 1:10; the PDMS comprises PDMS prepolymer and curing agent, with a mass ratio of 10:1.

[0018] Furthermore, the mass ratio of silica / polyurea composite microparticles to graphite microparticles in S2 is 10:1 to 1:1.

[0019] Furthermore, the dispersion conditions of the silica / polyurea composite microparticles and graphite powder described in S2 are as follows: first, magnetic stirring for 30 minutes, followed by ultrasonication for 15 minutes.

[0020] Furthermore, the fluoroalkyl silane described in S3 is one or more of perfluorodecyltrichlorosilane, perfluorooctyltrichlorosilane, perfluorododecyltrichlorosilane, perfluorooctyltriethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltriethoxysilane, and heptadecafluorodecyltrimethoxysilane.

[0021] Furthermore, the mass ratio of the fluoroalkylsilane to n-hexane described in S3 is 1:20 to 1:200.

[0022] Furthermore, the coating method described in S2 is one or more of spin coating, blade coating, and spray coating; the coating method described in S3 is spray coating or dip coating.

[0023] The polyurea photothermal anti-icing coating provided by this invention can be applied to anti-icing of electrical equipment, and preferably to anti-icing of insulators of power transmission lines.

[0024] This invention provides a method for preparing a polyurea photothermal anti-icing coating with excellent friction resistance and durability. The coating exhibits excellent anti-icing and de-icing performance, has significant application value, and possesses the following advantages:

[0025] 1. The polyurea photothermal anti-icing coating has a large contact angle (>147°) and a small roll-off angle (<10°), which allows water droplets to easily roll off the surface;

[0026] 2. High photothermal conversion efficiency, with a significant temperature rise (>60℃) under sunlight irradiation;

[0027] 3. Excellent anti-icing performance; compared with bare glass, it delays icing time by 3522.7% and has low ice adhesion strength (<30 kPa);

[0028] 4. Excellent durability. After being subjected to tests such as gravel impact, acid and alkali salt immersion, and freezing / de-icing cycles, the water contact angle changes little and the ice adhesion strength is low.

[0029] 5. This coating has good anti-icing effect under low light conditions. Attached Figure Description

[0030] Figure 1 SEM images of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention: (a) is a SEM image at a low magnification, and (b) is a partial magnified image of (a).

[0031] Figure 2 The contact angle diagram is shown for the polyurea photothermal anti-icing coating prepared in Example 1 of this invention.

[0032] Figure 3 The temperature rise diagram of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention under different intensities of sunlight irradiation is shown.

[0033] Figure 4 This is a thermal infrared image of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention under one solar irradiation.

[0034] Figure 5 Optical image showing delayed icing of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention.

[0035] Figure 6 The ice adhesion strength of the polyurea photothermal anti-icing coating prepared in Example 1 of this invention.

[0036] Figure 7 The graph shows the relationship between the contact angle, rolling angle and friction cycle of the polyurea photothermal anti-icing coating prepared in Example 1 of this invention during a gravel impact test.

[0037] Figure 8 The image shows the acid, alkali and salt resistance test results of the polyurea photothermal anti-icing coating prepared in Example 1 of this invention.

[0038] Figure 9 The figure shows the icing-melting cycle test results of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention.

[0039] Figure 10 Optical image of the de-icing effect of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention under weak light irradiation. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments. These embodiments are merely illustrative of the invention and should not be considered as specific limitations thereof.

[0041] Example 1

[0042] S1: Synthesis of silica / polyurea composite microparticles: The first batch of silica sol and polyurea resin were mixed in acetone solvent at a mass ratio of 5:1:250. After stirring evenly in a 30°C water bath, isoflurane diisocyanate was added and stirring was continued for 1 hour. Subsequently, the second batch of silica sol was added and stirred, with a mass ratio of 1:1:5 between polyurea resin, isoflurane diisocyanate, and the second batch of silica sol. The mixture was separated using a high-speed centrifuge at 5000 rpm, and then washed three times with a mixture of water and acetone to remove unattached SiO2 nanoparticles. The precipitate was dried in an oven at 60°C and ground to obtain silica / polyurea composite microparticles.

[0043] S2: Preparation of polyurea photothermal coating: The silica / polyurea composite microparticles obtained in S1 were mixed and dispersed with graphite microparticles in ethyl acetate. The mass ratio of silica / polyurea composite microparticles, graphite microparticles, and ethyl acetate was 5:2:150, resulting in a uniformly dispersed silica / polyurea / graphite suspension. PDMS was dissolved in n-hexane, with a mass ratio of PDMS to n-hexane of 1:20. Subsequently, 10 g of the PDMS n-hexane solution was coated onto a clean glass substrate using a blade coating method. After being placed at room temperature for 60 min, two layers of silica / polyurea / graphite suspension were coated, each layer containing 15 g of silica / polyurea / graphite suspension. The coating was then cured at 60 °C to obtain a polyurea photothermal coating.

[0044] S3: Surface hydrophobication treatment of polyurea photothermal coating: perfluorooctyltrimethoxysilane and n-hexane are mixed at a mass ratio of 1:100 to obtain a hydrophobic modification liquid; 15g of the hydrophobic modification liquid is sprayed onto the polyurea photothermal coating obtained in S2 and dried at 60℃ to obtain a polyurea photothermal anti-icing coating.

[0045] Tests showed that the polyurea photothermal anti-icing coating prepared in this embodiment has a thickness of 150 μm, a water droplet contact angle of 152 ± 1.5°, and a roll-off angle of 8 ± 0.5°.

[0046] Example 2

[0047] The method is the same as in Example 1, except that: in S1, the mass ratio of the first batch of silica sol, polyurea resin and acetone is 4:1:200, and the mass ratio of polyurea resin, isoflurane diisocyanate and the second batch of silica sol is 1:1:4; in S2, the mass ratio of silica / polyurea composite microparticles, graphite microparticles and ethyl acetate is 1:1:30.

[0048] Tests showed that the polyurea photothermal anti-icing coating prepared in this embodiment has a thickness of 120 μm, a water droplet contact angle of 150 ± 1.5°, and a roll-off angle of 11 ± 0.5°.

[0049] Example 3

[0050] The method is the same as in Example 1, except that: in S1, the mass ratio of the first batch of silica sol, polyurea resin and acetone is 2.5:1:120, and the mass ratio of polyurea resin, isophorone diisocyanate and the second batch of silica sol is 1:1.5:2.5; in S2, the mass ratio of silica / polyurea composite microparticles to graphite microparticles is 2:1, and the mass ratio of PDMS to n-hexane is 1:40; in S3, the fluoroalkyl silane is perfluorodecyltrichlorosilane, and the mass ratio of fluoroalkyl silane to n-hexane is 1:200.

[0051] Tests showed that the polyurea photothermal anti-icing coating prepared in this embodiment had a thickness of 120 μm, a water droplet contact angle of 149 ± 1.5°, and a roll-off angle of 13 ± 0.5°.

[0052] Example 4

[0053] The method is the same as in Example 1, except that: in S1, the mass ratio of the first batch of silica sol, polyurea resin and acetone is 4:1:200, and the mass ratio of polyurea resin, isoflurane diisocyanate and the second batch of silica sol is 1:2:4; in S2, the mass ratio of silica / polyurea composite microparticles, graphite microparticles and ethyl acetate is 2:1:50, and the mass ratio of PDMS to n-hexane is 1:50; in S3, the fluoroalkylsilane is perfluorodecyltrichlorosilane, and the mass ratio of fluoroalkylsilane to n-hexane is 1:200.

[0054] Tests showed that the polyurea photothermal anti-icing coating prepared in this embodiment has a thickness of 120 μm, a water droplet contact angle of 150 ± 1.5°, and a roll-off angle of 11 ± 0.5°.

[0055] Example 5

[0056] The method is the same as in Example 1, except that in S2, the mass ratio of silica / polyurea composite microparticles, graphite microparticles, and ethyl acetate is 4:1:100, and the mass ratio of PDMS to n-hexane is 1:40. In S3, the mass ratio of fluoroalkylsilane to n-hexane is 1:200.

[0057] Tests showed that the polyurea photothermal anti-icing coating prepared in this embodiment has a thickness of 150 μm, a water droplet contact angle of 151 ± 1.5°, and a roll-off angle of 9 ± 0.5°.

[0058] Comparative Example 1

[0059] The method is the same as in Example 1, except that the mass ratio of the first batch of silica sol to the second batch of silica sol is 2:1.

[0060] Comparative Example 2

[0061] The method is the same as in Example 1, except that the mass ratio of the first batch of silica sol to the second batch of silica sol is 1:2.

[0062] Both Comparative Example 1 and Comparative Example 2 exhibited severe agglomeration and consolidation during the reaction process, and silica could not be uniformly dispersed on the polyurea particles. The resulting polyurea photothermal anti-icing coating had a WCA < 140° and a WCA < 90° after 20 wear cycles.

[0063] The microstructure of the polyurea photothermal de-icing coating obtained in Example 1 was observed using a JSM7100F field emission scanning electron microscope (SEM), as follows: Figure 1 As shown.

[0064] WCA and SA were measured using an SCI3000F dynamic contact angle meter and 10 µl of deionized water. The WCA of the polyurea photothermal de-icing coating obtained in Example 1, as shown... Figure 2 As shown.

[0065] The sample surface temperature rose after being irradiated with a solar simulator (Oriel 94023 a, Newport) as the light source. Temperature and infrared images of the sample were acquired using a portable infrared imager (HM-TPH36-10VF / W, HIKMICRO). The temperature rise results of the polyurea photothermal de-icing coating obtained in Example 1 under different intensities of sunlight irradiation are shown in [Figure 1]. Figure 3 , Figure 4 This is a thermal infrared image of the polyurea photothermal de-icing coating obtained in Example 1 under solar irradiation.

[0066] The freezing delay time test was conducted by placing the sample on a cooling platform at -15℃±0.5℃ with an ambient humidity of 30%±5%. Figure 5Optical image showing delayed icing of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention.

[0067] The adhesion strength between ice and the surface is determined by measuring the shear force of ice using a digital thrust meter (HP-20). Figure 6 The ice adhesion strength of the polyurea photothermal anti-icing coating prepared in Example 1 of this invention.

[0068] The surface durability was evaluated using a sand impact test, an acid and alkali resistance test, and an icing-de-icing cycle test. The sand impact test involved a height of 40 cm and a sample tilt angle of 30°. The acid and alkali resistance test involved immersion for 60 hours. The icing-de-icing cycle test consisted of 40 cycles of freezing, thawing, and refreezing. Figure 7 The graph shows the relationship between the contact angle (WCA), roll-off angle (SA), and friction cycle of the polyurea photothermal anti-icing coating prepared in Example 1 of this invention during a gravel impact test. Figure 8 The image shows the acid, alkali and salt resistance test results of the polyurea photothermal anti-icing coating prepared in Example 1 of this invention. Figure 9 The figure shows the icing-melting cycle test results of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention.

[0069] Figure 10 Optical image of the de-icing effect of the polyurea photothermal anti-icing coating prepared in Example 1 of the present invention under weak light irradiation.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a polyurea photothermal anti-icing coating, characterized in that: Includes the following steps: S1. Synthesis of silica / polyurea composite microparticles: The first batch of silica sol and polyurea resin were mixed in acetone solvent and stirred at a constant temperature of 30°C; then diisocyanate and the second batch of silica sol were added in sequence; after high-speed centrifugation, washing, drying and grinding, silica / polyurea composite microparticles were obtained. S2. Preparation of polyurea photothermal coating: The silica / polyurea composite microparticles obtained in S1 were mixed and dispersed with graphite micron particles in ethyl acetate to obtain a uniformly dispersed silica / polyurea / graphite suspension. PDMS was dissolved in n-hexane and then coated onto a clean glass substrate. After being left at room temperature for 30-60 minutes, two layers of silica / polyurea / graphite suspension were coated and cured at 60°C to obtain a polyurea photothermal coating. S3. Surface hydrophobication treatment of polyurea photothermal coating: A hydrophobic modified solution was obtained by uniformly mixing fluoroalkylsilane and n-hexane. A hydrophobic modification liquid was coated on the surface of the polyurea photothermal coating obtained in S2 and dried at 60°C to obtain a polyurea photothermal anti-icing coating. The mass ratio of the first batch of silica sol to the second batch of silica sol mentioned in S1 is 1:1; S1 The diisocyanate is one or more of isoflurone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate; The total amount of the first and second batches of silica sol in S1 is in a mass ratio of 2:1 to 20:1 to polyurea resin; the mass ratio of diisocyanate to polyurea resin is 1:1 to 5:

1. The mass ratio of silica / polyurea composite microparticles to graphite microparticles described in S2 is 10:1 to 1:

1.

2. The method for preparing a polyurea photothermal anti-icing coating according to claim 1, characterized in that: The polyurea resin mentioned in S1 is an aspartic aliphatic polyurea resin.

3. The method for preparing a polyurea photothermal anti-icing coating according to claim 1, characterized in that: The mass ratio of PDMS to n-hexane in S2 is 1:50 to 1:10; the PDMS includes PDMS prepolymer and curing agent, with a mass ratio of 10:

1.

4. The method for preparing a polyurea photothermal anti-icing coating according to claim 1, characterized in that: The dispersion conditions for the silica / polyurea composite microparticles and graphite microparticles described in S2 are as follows: first, magnetic stirring for 30 minutes, followed by ultrasonication for 15 minutes.

5. The method for preparing a polyurea photothermal anti-icing coating according to claim 1, characterized in that: The fluoroalkyl silane described in S3 is one or more of perfluorodecyltrichlorosilane, perfluorooctyltrichlorosilane, perfluorododecyltrichlorosilane, perfluorooctyltriethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltriethoxysilane, and heptadecafluorodecyltrimethoxysilane.

6. The method for preparing a polyurea photothermal anti-icing coating according to claim 1, characterized in that: The mass ratio of the fluoroalkylsilane to n-hexane described in S3 is 1:20 to 1:

200.

7. The method for preparing a polyurea photothermal anti-icing coating according to claim 1, characterized in that: The coating method described in S2 is one or more of spin coating, scraping coating, and spraying coating; the coating method described in S3 is spraying or dip coating.

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