SUPERHYDROPHOBIC COATING WITH ABRASION RESISTANCE AND PREPARATION METHOD THEREOF

Abstract

Disclosed are a superhydrophobic coating with abrasion resistance and a preparation method thereof. The coating has a composite structure formed by a nanohybrid composed of nano-SiO.sub.2 and multi-wallet carbon nanotubes, and a resin as a matrix.

Claims

1. A superhydrophobic coating with abrasion resistance, having a composite structure formed by a nanohybrid composed of nano-SiO.sub.2 and multi-walled carbon nanotubes, and a resin as a matrix.

2. The superhydrophobic coating with abrasion resistance of claim 1, wherein the nanohybrid composed of nano-SiO.sub.2 and multi-walled carbon nanotubes accounts for 20-30% by mass of the resin.

3. The superhydrophobic coating with abrasion resistance of claim 1, wherein the resin is one selected from the group consisting of epoxy resin, polyurethane, unsaturated polyester resin, and acrylic resin.

4. The superhydrophobic coating with abrasion resistance of claim 1, wherein the superhydrophobic coating has a thickness of 40-120 sm.

5. The superhydrophobic coating with abrasion resistance of claim 1, wherein the nano-SiO.sub.2 has a particle size of 20-200 nm, and the multi-walled carbon nanotubes have a diameter of 10-50 nm.

6. A method for preparing the superhydrophobic coating with abrasion resistance of claim 1, comprising the following steps: (1) modifying multi-walled carbon nanotubes to obtain multi-walled carbon nanotubes with amino groups on a surface thereof, modifying nano-SiO.sub.2 to obtain nano-SiO.sub.2 with epoxy groups on a surface thereof, and mixing the multi-walled carbon nanotubes with amino groups on the surface thereof and the nano-SiO.sub.2 with epoxy groups on the surface thereof in acetone, to prepare nanohybrid composed of the nano-SiO.sub.2 and the multi-walled carbon nanotubes; (2) uniformly dispersing the nanohybrid prepared in step (1) in acetone, and then uniformly mixing with a resin to form a homogeneous liquid, which is a hybrid-resin composite solution; and (3) uniformly spraying the hybrid-resin composite solution on a surface of a substrate, and curing at a temperature of 40-80° C. for 12-24 h to obtain the superhydrophobic coating with abrasion resistance.

7. The method of claim 6, wherein in step (1), modifying multi-walled carbon nanotubes to obtain multi-walled carbon nanotubes with amino groups on the surface thereof is conducted as follows: uniformly dispersing the multi-walled carbon nanotubes in a mixed solution of hydrochloric acid and nitric acid in a concentration ratio of 1:1, refluxing to obtain a carboxylated surface, and grafting 0.5-1.5% by mass of silane coupling agent KH550 onto the carboxylated surface.

8. The method of claim 6, wherein in step (1), modifying nano-SiO.sub.2 to obtain nano-SiO.sub.2 with epoxy groups on the surface thereof is conducted as follows: modifying the nano-SiO.sub.2 by using 0.5-1.5% by mass of silane coupling agent KH560.

9. The method of claim 6, wherein in step (1), mixing the multi-walled carbon nanotubes with amino groups on the surface thereof and the nano-SiO.sub.2 with epoxy groups on the surface thereof in acetone is conducted by magnetic stirring for 64-80 h with a mass ratio of the multi-walled carbon nanotubes to the nano-SiO.sub.2 ranging from 1:1 to 5:1, to obtain the nanohybrid composed of the nano-SiO.sub.2 and the multi-walled carbon nanotubes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1a is a transmission electron microscope image of the nanohybrid composed of nano-SiO.sub.2 and multi-walled carbon nanotubes prepared in Example 1; FIG. 1b is a scanning electron microscope image of the hybrid-resin composite coating prepared in Example 1; and FIG. 1c is an image showing a water contact angle on the hybrid-resin composite coating prepared in Example 1.

[0024] FIG. 2a is a scanning electron microscope image of the hybrid-resin composite coating prepared in Example 2 before being stuck; and FIG. 2b is a scanning electron microscope image of the hybrid-resin composite coating prepared in Example 2 after being stuck.

[0025] FIG. 3 is a curve chart showing a variation curve of the water contact angle on the surface of a hybrid-resin composite coating prepared in Example 3 after being repeatedly stuck, and a variation curve of the water contact angle on the surface of a multi-walled carbon nanotube-resin composite coating after being repeatedly stuck.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present disclosure is further described below in conjunction with examples and the accompanying drawings. The following examples are illustrative rather than limiting, and the protection scope of the present disclosure cannot be limited by the following examples.

Example 1

[0027] Step 1: A stainless steel sheet was sanded with a sandpaper, ultrasonically cleaned with acetone, alcohol and deionized water in sequence, and dried with cold air.

[0028] Step 2: Multi-walled carbon nanotubes with a diameter of 10 nm were dispersed in a mixed solution of hydrochloric acid and nitric acid in a concentration ratio of 1:1, and the resulting mixture was refluxed at 80° C. for 12 h, obtaining a carboxylated surface. 0.5% of silane coupling agent KH550 was then added thereto and the resulting mixture was kept at a temperature of 80° C. and stirred at a rate of 300 rpm for 24 h, obtaining modified multi-walled carbon nanotubes. The modified multi-walled carbon nanotubes were cleaned three times respectively with toluene and deionized water in sequence, and dried in vacuum, obtaining multi-walled carbon nanotubes with amino groups on the surface thereof.

[0029] Step 3: 0.5% of silane coupling agent KH560 was added to 20 mL of deionized water and the resulting mixture was magnetically stirred at a rate of 300 rpm for 30 min to fully hydrolyze the silane coupling agent KH560. Nano-SiO.sub.2 with a particle size of 20 nm was added thereto, and subjected to an ultrasonic treatment at ambient temperature for 2 h, and dried at 60° C. for 24 h, obtaining nano-SiO.sub.2 with epoxy groups on the surface thereof.

[0030] Step 4: The nano-SiO.sub.2 with epoxy groups on the surface thereof and the multi-walled carbon nanotubes with amino groups on the surface thereof were added to acetone in a ratio of 1:1, stirred at a rate of 600 rpm at ambient temperature for 64 h, cleaned by suction filtration with deionized water for three times, and dried at 80° C., obtaining nanohybrid composed of nano-SiO.sub.2 and multi-walled carbon nanotubes.

[0031] Step 5: 0.4 g of the nanohybrid were dispersed in acetone and magnetically stirred at a rate of 600 rpm for 30 min, obtaining a nanohybrid-containing solution.

[0032] Step 6: 2 g of epoxy resin was dissolved in the nanohybrid-containing solution by stirring at a rate of 300 rpm at ambient temperature, obtaining a homogeneous solution, which is a hybrid-resin composite solution.

[0033] Step 7: The hybrid-resin composite solution was sprayed on a surface of the stainless steel sheet, obtaining a wet coating.

[0034] Step 8: The wet coating was cured and dried at 40° C. for 24 h, obtaining a cured coating (i.e., hybrid-resin composite coating) with a thickness of 40 μm.

[0035] FIG. 1a is a transmission electron microscope image of the nanohybrid composed of nano-SiO.sub.2 and multi-walled carbon nanotubes prepared in Example 1; FIG. 1b is a scanning electron microscope image of the surface of the hybrid-resin composite coating prepared in Example 1; and FIG. 1c is an image showing a water contact angle on the hybrid-resin composite coating prepared in Example 1. The nano-SiO.sub.2 with epoxy groups on the surface thereof and multi-walled carbon nanotubes with amino groups on the surface thereof were linked by chemical bonds, forming aggregates of micro-/nano-structure on the surface of the coating. The water contact angle on the composite coating reaches 159.2°.

Example 2

[0036] Step 1: An aluminum sheet was sanded with sandpaper, ultrasonically cleaned with acetone, alcohol and deionized water in sequence, and dried with cold air.

[0037] Step 2: Multi-walled carbon nanotubes with a diameter of 30 nm were dispersed in a mixed solution of hydrochloric acid and nitric acid, and the resulting mixture was refluxed at 80° C. for 12 h, obtaining a carboxylated surface. 1.0% of silane coupling agent KH550 was then added thereto and the resulting mixture was kept at a temperature of 80° C. and stirred at a rate of 300 rpm for 24 h, obtaining modified multi-walled carbon nanotubes. The modified multi-walled carbon nanotubes were cleaned three times respectively with toluene and deionized water in sequence, and dried in vacuum, obtaining multi-walled carbon nanotubes with amino groups on the surface thereof.

[0038] Step 3: 1.0% of silane coupling agent KH560 was added to 20 mL of deionized water and the resulting mixture was magnetically stirred at a rate of 300 rpm for 30 min to fully hydrolyze the silane coupling agent KH560. Nano-SiO.sub.2 with a particle size of 100 nm was added thereto, and subjected to an ultrasonic treatment at ambient temperature for 2 h, and dried at 60° C. for 24 h, obtaining nano-SiO.sub.2 with epoxy groups on the surface thereof.

[0039] Step 4: The nano-SiO.sub.2 with epoxy groups on the surface thereof and the multi-walled carbon nanotubes with amino groups on the surface thereof were added to acetone in a ratio of 3:1, stirred at a rate of 600 rpm at ambient temperature for 70 h, cleaned by suction filtration with deionized water for three times, and dried at 80° C., obtaining nanohybrid composed of nano-SiO.sub.2 and multi-walled carbon nanotubes.

[0040] Step 5: 0.75 g of nanohybrid were dispersed in acetone and magnetically stirred at a rate of 600 rpm for 30 min, obtaining a nanohybrid-containing solution.

[0041] Step 6: 3 g of polyurethane was dissolved in the nanohybrid-containing solution by stirring at a rate of 300 rpm at ambient temperature, obtaining a homogeneous solution, which is a hybrid-resin composite solution.

[0042] Step 7: The hybrid-resin composite solution was sprayed on a surface of the aluminum sheet, obtaining a wet coating.

[0043] Step 8: The wet coating was cured and dried at 60° C. for 18 h, obtaining a cured coating (i.e., hybrid-resin composite coating) with a thickness of 80 μm.

[0044] Step 9: The surface of the hybrid-resin composite coating was repeatedly stuck for 200 times using a 3M adhesive tape.

[0045] FIG. 2a is a scanning electron microscope image of the surface of the hybrid-resin composite coating prepared in Example 2 before being stuck; and FIG. 2b is a scanning electron microscope image of the surface of the hybrid-resin composite coating prepared in Example 2 after being stuck for 200 times. The micro-/nano-structure on the surface of the hybrid-resin composite coating improves the surface roughness of the coating, and winding-locked hybrids endow the surface of the coating with excellent peeling resistance. Thus, even being repeatedly stuck for 200 times, the surface of the coating still maintains layered micro-/nano-structure, which is beneficial to maintaining the superhydrophobicity.

Example 3

[0046] Step 1: A low-alloy steel was sanded with sandpaper, ultrasonically cleaned with acetone, alcohol and deionized water in sequence, and dried with cold air.

[0047] Step 2: Multi-walled carbon nanotubes with a diameter of 50 nm were dispersed in a mixed solution of hydrochloric acid and nitric acid, and the resulting mixture was refluxed at 80° C. for 12 h, obtaining a carboxylated surface. 1.5% of silane coupling agent KH550 was then added thereto and the resulting mixture was kept at a temperature of 80° C., and stirred at a rate of 300 rpm for 24 h, obtaining modified multi-walled carbon nanotubes. The modified multi-walled carbon nanotubes were cleaned three times respectively with toluene and deionized water in sequence, and dried in vacuum, obtaining multi-walled carbon nanotubes with amino groups on the surface thereof.

[0048] Step 3: 1.5% of silane coupling agent KH560 was added to 20 mL of deionized water and the resulting mixture was magnetically stirred at a rate of 300 rpm for 30 min to fully hydrolyzee the silane coupling agent KH560. Nano-SiO.sub.2 with a particle size of 200 nm was added thereto, and subjected to an ultrasonic treatment at ambient temperature for 2 h, and dried at 60° C. for 24 h, obtaining nano-SiO.sub.2 with epoxy groups on the surface thereof.

[0049] Step 4: The nano-SiO.sub.2 with epoxy groups on the surface thereof and the multi-walled carbon nanotubes with amino groups on the surface thereof were added to acetone in a ratio of 5:1, stirred at a rate of 600 rpm at ambient temperature for 80 h, cleaned by suction filtration with deionized water for three times, and dried at 80° C., obtaining nanohybrid composed of nano-SiO.sub.2 and multi-walled carbon nanotubes.

[0050] Step 5: 0.6 g of nanohybrid were dispersed in acetone and magnetically stirred at a rate of 600 rpm for 30 min, obtaining a nanohybrid-containing solution.

[0051] Step 6: 2 g of acrylic resin was dissolved in the nanohybrid-containing solution by stirring at a rate of 300 rpm at ambient temperature, obtaining a homogeneous solution, which is a hybrid-resin composite solution.

[0052] Step 7: The hybrid-resin composite solution was sprayed on a surface of the low-alloy steel, obtaining a wet coating.

[0053] Step 8: The wet coating was cured and dried at 80° C. for 12 h, obtaining a cured coating (i.e., hybrid-resin composite coating) with a thickness of 120 μm.

[0054] Step 9: The surface of the hybrid-resin composite coating was repeatedly stuck with a 3M adhesive tape until the water contact angle on the coating was below 150°, during which the water contact angle on the coating was measured every 10 times of being stuck.

[0055] FIG. 3 is a curve chart showing a variation curve of the water contact angle on the surface of the hybrid-resin composite coating prepared in Example 3 after being repeatedly stuck, and a variation curve of the water contact angle on the surface of a multi-walled carbon nanotube-resin composite coating after being repeatedly stuck. After being repeatedly stuck for 300 times, the water contact angle on the hybrid-resin composite coating was still kept at 150°. This is due to the fact that the winding-locked effect of the nano-SiO.sub.2 with epoxy groups on the surface thereof and multi-walled carbon nanotubes with amino groups on the surface thereof endowed the surface of the coating with excellent peeling resistance, and thus the coating was not easy to be damaged during friction. Regarding the multi-walled carbon nanotube-resin composite coating, the water contact angle was reduced to 150° after being repeatedly stuck for 80 times, which is due to the poor adhesion of the multi-walled carbon nanotubes to the surface of the coating and poor abrasion resistance of the coating. The above studies show that the winding-locked structure of nano-SiO.sub.2 and multi-walled carbon nanotubes played a key role in improving the abrasion resistance of the coating.