Nano silicon dioxide-epoxy resin super-hydrophobic coating and preparation method thereof

Abstract

The invention discloses a nano silicon dioxide-epoxy resin super-hydrophobic coating and a preparation method thereof. The coating is prepared from hydrophobic gas-phase nano silicon dioxide powder, epoxy resin E44, absolute ethyl alcohol, a low-molecular polyamide curing agent 650 and a silane coupling agent. The mass ratio of the hydrophobic gas-phase nano silicon dioxide powder to the epoxy resin E44 to the low-molecular polyamide curing agent 650 is 0.4: 0.386: (0.161-0.214). The absolute ethyl alcohol and the epoxy resin are used as main raw materials, the effects of the absolute ethyl alcohol and the epoxy resin are combined, and the super-hydrophobic coating with excellent super-hydrophobic performance can be obtained by spraying the absolute ethyl alcohol and the epoxy resin on the surface of an ancillary facility through a spraying method with simple operation and drying at room temperature, so that room-temperature curing, no toxicity and environment friendliness are realized; the coating is simple in ingredient, only five raw materials are used, the contact angle of the coating can reach 155 degrees, and the rolling angle can be as low as 3 degrees. And under the load of 50 g of a weight, after being polished by 1200-mesh abrasive paper for 2.5 m, the coating still has hydrophobicity, and shows good durability and mechanical stability.

Description

Technical Field

[0001] The present invention relates to the field of superhydrophobic materials, and particularly to a nano-silica-epoxy resin superhydrophobic coating. Background Art

[0002] With the rise of the national economy and the rapid development of society, the construction of transportation infrastructure is in full swing. Since the 20th century, the transportation industry in China has developed rapidly, especially in the field of expressways, with the mileage increasing rapidly, driving the construction of traffic basic ancillary facilities. And the maintenance and upkeep of traffic basic ancillary facilities are important links in the road operation stage. Inspired by the "lotus effect" in nature, people have discovered and studied many organisms with special wetting functions in nature. Through the research on organisms with superhydrophobic functions, a new shortcut is provided for the research and development of materials for superhydrophobic surfaces and superhydrophobic biomimetic materials. Combining modern advanced material processes, constructing a superhydrophobic coating on the surface of transportation infrastructure can effectively isolate the contact between the surface and moisture and exhibit good superhydrophobic performance.

[0003] At present, the research on the application of hydrophobic materials in the field of road traffic at home and abroad mainly includes two aspects: one is to incorporate snow melting and ice inhibiting materials into asphalt; the other is to prepare a superhydrophobic coating and artificially construct a low surface energy micro-nano rough structure. This structure has good superhydrophobic performance, mechanical stability performance, chemical stability performance, and anti-icing performance. With its excellent performance, it can effectively remove water droplets attached to the surface and take away dust to achieve anti-corrosion and self-cleaning, extend its service life, reduce the maintenance frequency, and greatly reduce the maintenance cost.

[0004] However, in the current research on superhydrophobic coatings, most of the solvents used are cyclohexane, ethyl acetate, isopropanone, etc. Such solvents are extremely volatile and toxic; and the dipping method and the process that requires heating and baking for curing not only have an impact on the physical health of construction workers, but also are not conducive to large-scale construction. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention proposes a nano-silica-epoxy resin superhydrophobic coating, which uses non-toxic absolute ethanol as a solvent, mixes hydrophobic gas-phase nano-silica particles and epoxy resin, adds a curing agent, and attaches the coating to the material surface by spraying. This coating has good self-cleaning performance and mechanical stability performance, and can be constructed on a large scale.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A nano-silica-epoxy resin superhydrophobic coating is composed of the following raw materials:

[0008] Hydrophobic gas-phase nano-silica powder;

[0009] Epoxy resin E44;

[0010] Absolute ethanol;

[0011] Low molecular weight polyamide curing agent 650;

[0012] Silane coupling agent;

[0013] The mass ratio of the hydrophobic fumed nano-silica powder, epoxy resin E44, and low molecular weight polyamide curing agent 650 is: 0.4:0.386:(0.161 - 0.214).

[0014] Among them, epoxy resin E44 plays a role in bonding the base material. Epoxy resin E44 is a kind of high molecular polymer, which is the polycondensation product of epichlorohydrin and bisphenol A or polyol; due to the chemical activity of the epoxy group, it can be ring-opened by a variety of compounds containing active hydrogen, and cured and cross-linked to form a network structure.

[0015] The hydrophobic fumed nano-silica plays a role in constructing the micro-nano structure.

[0016] The low molecular weight polyamide curing agent 650 plays a role in promoting the curing reaction. The low molecular weight polyamide curing agent 650 has excellent bonding properties and good adhesion to a variety of base materials. During the preparation of the coating, by adding a curing agent, the coating has good water resistance and salt spray resistance; the polyamide molecule contains a long aliphatic hydrocarbon chain, and the aliphatic hydrocarbon chain isolates the rigid inner benzene ring in the epoxy resin molecule, enabling the bond to have a greater degree of freedom when under load or impact, making the cured product have excellent flexibility. The low molecular weight polyamide curing agent 650 can be cured at room temperature, and the operation is convenient.

[0017] The silane coupling agent is between the inorganic and organic interfaces, combining epoxy resin E44 with the hydrophobic fumed nano-silica, and can form a bonding layer of organic matrix - coupling agent - inorganic matrix. This system has the functions of thickening and increasing viscosity. Therefore, in the coating of the present invention, the silane coupling agent plays a role in improving the material compatibility and adhesion.

[0018] Absolute ethanol plays the role of a solvent for dissolving and mixing each phase.

[0019] Furthermore, the dosage of the absolute ethanol is:

[0020] The ratio of absolute ethanol to the total mass of the hydrophobic fumed nano-silica powder, epoxy resin E44, and low molecular weight polyamide curing agent 650 is 15 ml / g.

[0021] Furthermore, the dosage of the silane coupling agent is:

[0022] The silane coupling agent accounts for 1% of the total mass of the hydrophobic fumed nano-silica powder, epoxy resin E44, and low-molecular-weight polyamide curing agent 650.

[0023] Furthermore, the silane coupling agent is an aminopropyltriethoxysilane coupling agent with a molecular structural formula of H2NCH2CH2CH2Si(OC2H5)3.

[0024] A preparation method of a nano-silica / epoxy resin superhydrophobic coating includes the following steps:

[0025] S1: Add the hydrophobic fumed nano-silica powder into absolute ethanol, stir to make it evenly dispersed, and form an absolute ethanol suspension of the hydrophobic fumed nano-silica powder.

[0026] S2: Add epoxy resin E44, low-molecular-weight polyamide curing agent 650, and the silane coupling agent into the absolute ethanol suspension of the hydrophobic fumed nano-silica powder obtained in S1, and stir to make them evenly mixed.

[0027] S3: Spray the evenly mixed solution obtained in S2 on the surface of the material, and dry it at room temperature to form a nano-silica / epoxy resin superhydrophobic coating.

[0028] The beneficial effects of the present invention are as follows:

[0029] (1) The present invention uses absolute ethanol and epoxy resin as the main raw materials, combines their functions, and sprays them on the surface of auxiliary facilities through a simple spraying method, and dries them at room temperature, then a superhydrophobic coating with excellent superhydrophobic performance can be obtained, realizing room temperature curing, non-toxic and environmentally friendly.

[0030] (2) The coating formulation of the present invention is simple, only using five raw materials, and the contact angle of the coating can reach 155°, and the rolling angle can be as low as 3°. And under the load of a 50g weight, after being polished with 1200-mesh sandpaper for 2.5 meters, it still has hydrophobicity, showing good durability and mechanical stability. Description of the Drawings

[0031] Figure 1 It is a flow chart of the preparation method of the nano-silica / epoxy resin superhydrophobic coating of the embodiment of the present invention.

[0032] Figure 2 It is the change curves of the contact angle and rolling angle of the coating in the sandpaper wear test. Among them, the three left-side figures are the contact angles of superhydrophobic group 2 and superhydrophobic group 3 at spraying amounts of 1 ml, 2 ml, and 3 ml respectively, and the three right-side figures are the rolling angles of superhydrophobic group 2 and superhydrophobic group 3 at spraying amounts of 1 ml, 2 ml, and 3 ml respectively.

[0033] Figure 3Figure for comparing the self-cleaning effects of the superhydrophobic group 3 coatings at a spraying volume of 3 ml. Among them, Figure (a) is a schematic diagram of using nano-carbon black tiled on the surface of a glass slide coated with 3 ml of SiO2-EP coating; Figure (b) is a schematic diagram of using nano-carbon black tiled on the surface of a clean glass slide; Figure (c) is a schematic diagram of the cleaning condition after using ultrapure water to simulate rainwater flushing the surface of the glass slide in Figure (a); Figure (d) is a schematic diagram of the cleaning condition after using ultrapure water to simulate rainwater flushing the surface of the glass slide in Figure (b). Detailed implementation manners

[0034] The present invention will be described in detail below according to the attached drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Example 1

[0036] S1: Weigh hydrophobic fumed nano-silica using an electronic balance, uniformly disperse it in 15 ml of absolute ethanol, add a magnetic stir bar and stir magnetically for 30 min to form an absolute ethanol suspension of nano-silica.

[0037] S2: Add epoxy resin E44, low molecular weight polyamide curing agent 650, and aminopropyltriethoxysilane coupling agent to the absolute ethanol suspension of nano-silica obtained in S1 respectively, and continue to stir magnetically for 2 h. The resulting solution is denoted as superhydrophobic group 1.

[0038] S3: Add the composite solution obtained in S2 to a spray gun using a pipette, and spray it onto the surface of a glass slide that has been washed and dried with ultrapure water and 95% ethanol solution. Control the distance between the nozzle and the glass slide surface to be 7 - 10 cm, the spray gun pressure to be 200 kPa, spray 3 - 4 times, and the spraying volumes are 1 ml, 2 ml, and 3 ml respectively. The number of each coating sample is 2. Dry at room temperature for 8 h to obtain a superhydrophobic coating. The specific process is as Figure 1 shown.

[0039] Example 2

[0040] The steps are the same as those in Example 1, and the resulting solution is denoted as superhydrophobic group 2.

[0041] Example 3

[0042] The steps are the same as those in Example 1, and the resulting solution is denoted as superhydrophobic group 3.

[0043] Comparative example

[0044] The steps are the same as those in Example 1, and the resulting solution is denoted as superhydrophobic group 4.

[0045] The compositions of various raw materials in Examples 1 - 3 and Comparative Example 1 are shown in Table 1.

[0046] Table 1 Material Composition

[0047]

[0048] The performance characterization and testing of the superhydrophobic coatings prepared in the examples and comparative examples are carried out below.

[0049] 1. Contact Angle and Rolling Angle Tests

[0050] A static contact angle measuring instrument is used to measure the contact angle (WCA) and rolling angle (SA) of the sample with water. Different parts of the same sample are measured 3 times repeatedly, and the average value is taken. Taking Superhydrophobic Group 1 - Superhydrophobic Group 4 as examples, the measurement results of their contact angles and rolling angles are shown in Table 2 and Table 3 respectively.

[0051] Table 2 Measurement Results of Sample Contact Angles

[0052]

[0053] Table 3 Measurement Results of Sample Rolling Angles

[0054]

[0055] As can be seen from Table 2 and Table 3, Superhydrophobic Group 1, Superhydrophobic Group 2, and Superhydrophobic Group 3 maintain superhydrophobicity at three thicknesses. Only Superhydrophobic Group 4 in the comparative example shows superhydrophobicity at the thickness of 3 ml solution spraying. Among them, Superhydrophobic Group 2 and Superhydrophobic Group 3 show more excellent superhydrophobic performance at different spraying thicknesses, with the contact angle reaching more than 154° and the rolling angle less than 10°.

[0056] 2. Abrasion Resistance Test

[0057] The abrasion resistance test is carried out with sandpaper. A 50 g weight is placed on the sample, and it is pushed to move 25 cm on 1200 - mesh sandpaper. This is one cycle. After each cycle ends, its contact angle and rolling angle are measured, and this cycle is repeated until the contact angle of the sample is less than 140°. Taking Superhydrophobic Group 2 and Superhydrophobic Group 3 as examples, their test results are as Figure 2 shown.

[0058] From Figure 2As can be seen from the curves in [Figure 0], with the increase in the cycle period of the sandpaper cyclic friction, the contact angle and rolling angle of the superhydrophobic group coatings change. Overall, with the increase in the cycle period of the sandpaper cyclic friction, the contact angle of the superhydrophobic group coatings decreases, and the rolling angle increases. After 1 cycle of cyclic friction, the contact angles of the superhydrophobic group 2-1ml and superhydrophobic group 3-1ml coatings increase. After 5 cycles of cyclic friction, the contact angles of the superhydrophobic group 2-2ml and superhydrophobic group 3-2ml coatings recover. The contact angles of the superhydrophobic group 2-3ml and superhydrophobic group 3-3ml coatings fluctuate up and down within 5 cycles of friction. After 5 cycles of friction, the contact angles of all coatings show a downward trend. After 10 cycles of friction (2.5 m of friction on the sandpaper), the contact angles of the superhydrophobic group 2 and superhydrophobic group 3 coatings are both above 130°, maintaining the hydrophobic property and having good durability.

[0059] 3. Self-cleaning test

[0060] Observation Figure 3 From the cleaning conditions of the glass slides without coating and coated with SiO2-EP coating before and after being rinsed with ultrapure water as [Observation], it can be seen that on the surface of the glass slide without coating, most of the carbon black was washed away by the ultrapure water rinse, but there was still a little carbon black stain on its surface, and a large amount of water stains remained. The carbon black on the surface of the glass slide coated with SiO2-EP coating was completely washed away, and the surface remained dry without residual water stains. The self-cleaning effect was greatly improved compared with the glass slide without coating. This proves that the SiO2-EP coating has excellent self-cleaning ability. This is because the surface energy of the SiO2-EP coating is low, reducing the adsorption ability of the surface to microscopic particles, and it has a nano-microstructure, with a large contact angle and a small rolling angle. When water droplets fall on the coating surface, they will roll away easily in a spherical shape and take away the carbon black on the surface, thus realizing the function of surface self-cleaning.

[0061] Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not used to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, for those skilled in the art, they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention.

Claims

1. A nano-silica - epoxy resin superhydrophobic coating, characterized in that, It consists of the following raw materials: Hydrophobic fumed nano-silica powder; Epoxy resin E44; Absolute ethanol; Low molecular weight polyamide curing agent 650; Silane coupling agent; The mass ratio of the hydrophobic fumed nano-silica powder, epoxy resin E44, and low molecular weight polyamide curing agent 650 is: 0.4:0.386:(0.161 - 0.214).

2. The nano-silica - epoxy resin superhydrophobic coating according to claim 1, wherein The dosage of the absolute ethanol is: The ratio of absolute ethanol to the total mass sum of the hydrophobic fumed nano-silica powder, epoxy resin E44, and low molecular weight polyamide curing agent 650 is 15 ml / g.

3. The nano-silica - epoxy resin superhydrophobic coating according to claim 1, characterized in that, The dosage of the silane coupling agent is: The silane coupling agent accounts for 1% of the total mass of the hydrophobic fumed nano-silica powder, epoxy resin E44, and low molecular weight polyamide curing agent 650.

4. The nano-silica-epoxy resin superhydrophobic coating according to claim 1, wherein The silane coupling agent is aminopropyltriethoxysilane coupling agent.

5. A method for preparing a nano-silica / epoxy resin superhydrophobic coating as described in claim 1, characterized in that, It includes the following steps: S1: Add the hydrophobic fumed nano-silica powder into absolute ethanol, stir to make it evenly dispersed, and form an absolute ethanol suspension of the hydrophobic fumed nano-silica powder; S2: Add epoxy resin E44, low molecular weight polyamide curing agent 650, and silane coupling agent into the absolute ethanol suspension of the hydrophobic fumed nano-silica powder obtained in S1, and stir to make them evenly mixed; S3: Spray the evenly mixed solution obtained in S2 on the material surface and dry it at room temperature to form a nano-silica - epoxy resin superhydrophobic coating.

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