CN111892873A - A kind of super-hydrophobic coating with high binding force and preparation method thereof - Google Patents

Abstract

The invention discloses a high-binding force super-hydrophobic coating and a preparation method thereof. The coating comprises a binder and a hydrophobic coating. The preparation method mainly includes spraying the binder, spraying the hydrophobic coating, and heating and curing, and using the receptor as a metal matrix . The volume ratio of the raw materials of the binder components is: γ-glycidyl ether oxypropyltrimethoxysilane: distilled water: ethanol volume ratio of 2:1:9 to 4:7:9; the volume ratio of the hydrophobic coating is: multi-wall Carbon nanotubes 1.5～3g/L, silicon carbide powder 1～4 g/L, tetraethyl silicate 40～100mL/L, heptadecafluorodecyltrimethoxysilane hydrolyzate 20～80mL/L, ethanol as solvent . The binder used in the invention can form a covalent bond with the multi-walled carbon nanotubes and silicon carbide in the hydrophobic coating, and has high binding force, and the detachment area of the metal surface cross-cut method is less than 5%, which can ensure the long-term stability of the hydrophobic function. . The multi-walled carbon nanotubes used in the present invention can fill the pores formed in the process of silane curing and dehydration, so that the coating has good compactness and can effectively improve the corrosion resistance.

Description

A kind of super-hydrophobic coating with high binding force and preparation method thereof

technical field

The invention relates to the technical field of material preparation, in particular to a high-binding force super-hydrophobic coating and a preparation method thereof.

Background technique

Superhydrophobic surfaces have unique wetting properties, and their applications in anti-icing, self-cleaning and antifouling, anti-corrosion, biomedical, surface patterning, new transportation equipment, and oil-water separation have developed rapidly. So far, according to the construction of surface rough structure, its preparation methods are divided into: etching method, hydrothermal method, electrodeposition method, micro-arc oxidation method, spraying method and a combination of various methods.

The spraying method uses the spraying equipment to uniformly disperse and overlay the micro/nano-particle raw materials on the surface of the substrate to form a uniform coating with a certain rough structure on the surface of the substrate. The main advantages are: First, the substrate can be processed widely. , including most metal materials such as gold, silver, copper, iron, tin, zinc, magnesium, aluminum and titanium, as well as non-metallic materials such as plastics, rubber, glass, ceramics, fibers and wood. Second, it is not limited by the shape and size of the workpiece, and can be prepared in a large area, so it is especially suitable for hydrophobic treatment of large equipment. Third, the operation is simple and convenient, the cost is low, there is no dependence on special equipment, the coating efficiency is high, and it is easy to achieve mass production.

However, the preparation of superhydrophobic surfaces by spraying method still has many problems to be solved before the real industrialization. It is mainly limited by the problem of poor bonding force between the functional surface and the substrate. Zhiqiang Qian disclosed the following spraying technology in the thesis "Preparation and Properties of SiO ₂ /MWCNTs/PFOTES Superhydrophobic Composite Coatings" on p. A certain amount of carbon nanotubes aqueous solution was added to 20 mL of ethanol, and ultrasonically dispersed for 30 min; then a certain amount of concentrated ammonia water was added to the beaker, and the mixture was uniformly mixed by magnetic stirring at room temperature for 30 min. Finally, TEOS and PFOTES were slowly added to the beaker. , and continued stirring for 12 h to obtain a spray solution. 4 mL of the prepared suspension was uniformly sprayed onto the surface of the pretreated AZ31B magnesium alloy using a spray gun, the spray gun was about 15-20 cm away from the substrate, and the spray pressure was 0.2 MPa. Among them, during spraying, the magnesium alloy was placed on a hot plate at 120°C to accelerate the volatilization of ethanol. Finally, the magnesium alloy coating was dried in an oven at 150 °C for 1 h to obtain a superhydrophobic surface. Using the above spraying techniques, a surface with a certain hydrophobicity can be obtained. Unfortunately, the peeling area of the coating is greater than 65% after the adhesion test, and the adhesion between the coating and the substrate is poor, thus limiting its application in industry.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, provide a high-binding force super-hydrophobic coating and a preparation method thereof, and solve the problem of poor binding force when preparing a super-hydrophobic surface by the existing spraying technology.

The technical scheme of the present invention is: a kind of super-hydrophobic coating with high binding force and preparation method thereof, comprising the following steps:

Step S1: surface finishing: surface finishing the metal substrate to remove stains and oxides to obtain a finished substrate workpiece;

Step S2: spraying the binder: the gauge pressure of the spray gun is 0.25~0.40MPa, the horizontal movement speed of the vertical surface of the spray gun is 1~3cm/s, and the amount of the binder is 2~10L/㎡;

Step S3: spraying the hydrophobic paint: the gauge pressure of the spray gun is 0.25~0.40MPa, the horizontal movement speed of the vertical surface of the spray gun is 1~3cm/s, and the amount of the hydrophobic paint is 10~20L/㎡;

Step S4: Heating and curing: the substrate is cured at 120-200ºC for 2-16 hours, and the superhydrophobic coating is prepared after cooling.

Further, the metal matrix is a metal alloy, preferably, the metal alloy is a magnesium alloy or an aluminum alloy.

Further, the preparation method of the binder is as follows: the binder is configured according to the volume ratio of γ-glycidyl ether oxypropyltrimethoxysilane: distilled water: ethanol from 2:1:9 to 4:7:9, and it is allowed to stand for 10~ 120min.

Further, the preparation method of the hydrophobic coating: 1.5-3 g/L of multi-wall carbon nanotubes with a diameter of 0-50 nm, 1-4 g/L of silicon carbide powder with a diameter of 0.5-0.7 μm, 40-100 mL/L of tetraethyl silicate, Heptadecafluorodecyltrimethoxysilane hydrolyzed solution 20-80mL/L, ethanol as solvent, ultrasonically treated for 0-60min and then stirred for 0-120min.

Further, the preparation method of the heptadecafluorodecyltrimethoxysilane hydrolyzate is as follows: the volume ratio of heptadecafluorodecyltrimethoxysilane:distilled water:ethanol is 1:1:98 to 20:1:79.

Further, step S3 is performed within 1 to 10 minutes after the step S2 is completed.

Compared with the prior art, the present invention has the following beneficial effects:

(1) High binding force: the binder composed of silane used in the present invention can form covalent bonds with the multi-walled carbon nanotubes and silicon carbide in the hydrophobic coating, the hydrophobic functional layer is closely combined with the adhesive layer and the substrate, and the metal surface The shedding area of the cross-cut test is less than 5%.

(2) Good corrosion resistance: the multi-walled carbon nanotubes used in the present invention can fill the pores formed during the curing and dehydration of silane, so that the coating has good compactness and can effectively improve the corrosion resistance.

(3) Simple and convenient repair: the coating is easily damaged after being put into production and life, and the repairing method is simple and convenient, and the requirements for personnel and equipment are low.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments. However, the embodiments and protection scope of the present invention are not limited thereto.

Example 1

A magnesium alloy with a size of 50mm×50mm×5mm is used as the base material. The composition of the binder is configured according to the volume ratio of γ-glycidyl ether oxypropyltrimethoxysilane: distilled water: ethanol 3:1:8, and it is allowed to stand for 10 minutes. Preparation method of hydrophobic coating: 2 g/L of multi-walled carbon nanotubes with a diameter of 0 to 50 nm, 1 g/L of silicon carbide powder with a diameter of 0.5 to 0.7 μm, 40 mL/L of tetraethyl silicate, and hydrolysis of heptadecafluorodecyltrimethoxysilane liquid 20mL/L, ethanol as solvent, ultrasonically dispersed for 0.5h and then stirred for 0.5h. The heptafluorodecyltrimethoxysilane hydrolyzed solution is configured according to the volume ratio of heptadecafluorodecyltrimethoxysilane:distilled water:ethanol 1:1:98. The preparation process is as follows:

1) Pre-treatment: Use 200 ~ 1000# sandpaper to polish the surface of magnesium alloy, rinse and dry in sequence with tap distilled water;

2) Spraying binder: the gauge pressure of the spray gun is 0.25MPa, the horizontal movement speed of the spray gun vertical to the magnesium alloy surface is 1cm/s, and the amount of the binder is 2L/㎡;

3) Spraying the hydrophobic coating: 1min after the completion of step 2, the gauge pressure of the spray gun is 0.25MPa, the horizontal movement speed of the spray gun vertical to the magnesium alloy surface is 1cm/s, and the amount of the hydrophobic coating is 14L/㎡;

4) Heating and curing: The magnesium alloy was cured at 120ºC for 16 hours, and the super-hydrophobic magnesium alloy coating was prepared after cooling.

The obtained composite coating did not fall off in the cross-cut test, and the coating was uniformly combined with the substrate. The static contact angle of deionized water on the surface of the sample was measured by a VCA Optima contact angle meter from AST Company, and the droplet volume was 5 μL. At least 5 points were selected to collect data on each test surface, and the average value of the results could reach 151.9°, showing superhydrophobicity.

Example 2

The aluminum alloy with the size of 20mm×40mm×10mm is used as the base material. The composition of the binder is configured according to the volume ratio of γ-glycidyl ether oxypropyltrimethoxysilane: distilled water: ethanol 2:1:9, and it is allowed to stand for 30 minutes. Preparation method of hydrophobic coating: 2.5g/L of multi-walled carbon nanotubes with diameter of 0～50nm, 3g/L of silicon carbide powder with diameter of 0.5～0.7μm, 80mL/L of tetraethyl silicate, hydrolysis of heptadecafluorodecyltrimethoxysilane liquid 50mL/L, ethanol as solvent, ultrasonic dispersion for 0.5h and then stirring for 0.5h. Wherein the heptafluorodecyltrimethoxysilane hydrolyzate is configured according to the volume ratio of heptadecafluorodecyltrimethoxysilane:distilled water:ethanol 4:1:95. The preparation process is as follows:

(1) Pre-treatment: Use 200 ~ 1000# sandpaper to polish the aluminum alloy surface, rinse and dry in sequence with tap distilled water;

(2) Spraying binder: the gauge pressure of the spray gun is 0.3MPa, the horizontal movement speed of the spray gun vertical to the surface of the sample is 1.5cm/s, and the amount of binder is 4L/㎡;

(3) Spraying the hydrophobic coating: 1min after the completion of step 2, the gauge pressure of the spray gun is 0.3MPa, the horizontal movement speed of the spray gun vertical to the surface of the sample is 1.5cm/s, and the amount of the hydrophobic coating is 20L/㎡;

(4) Heat curing: Place the sample at 140ºC to cure for 2 hours, and then prepare the superhydrophobic coating after cooling.

The obtained composite coating did not fall off in the cross-cut test, and the coating was uniformly combined with the substrate. The static contact angle of deionized water on the surface of the sample was measured by a VCA Optima contact angle meter from AST Company, and the droplet volume was 5 μL. At least 5 points were selected to collect data on each test surface, and the average value of the results could reach 151.5°, showing superhydrophobicity.

Example 3

The aluminum alloy with the size of 20mm×40mm×10mm is used as the base material. The composition of the binder is configured according to the volume ratio of γ-glycidyl ether oxypropyltrimethoxysilane: distilled water: ethanol 2:1:9, and it is allowed to stand for 30 minutes. Preparation method of hydrophobic coating: 3g/L of multi-walled carbon nanotubes with a diameter of 0～50nm, 4g/L of silicon carbide powder with a diameter of 0.5～0.7μm, 100mL/L of tetraethyl silicate, and hydrolyzed solution of heptadecafluorodecyltrimethoxysilane 80mL/L, ethanol as solvent, ultrasonic dispersion for 60min. The heptafluorodecyltrimethoxysilane hydrolyzed solution is configured according to the volume ratio of heptadecafluorodecyltrimethoxysilane:distilled water:ethanol 20:1:79. The preparation process is as follows:

(1) Pre-treatment: Use 200 ~ 1000# sandpaper to polish the aluminum alloy surface, rinse and dry in sequence with tap distilled water;

(2) Spraying binder: the gauge pressure of the spray gun is 0.3MPa, the horizontal movement speed of the spray gun vertical to the surface of the sample is 2cm/s, and the amount of binder is 10L/㎡;

(3) Spraying the hydrophobic paint: 10 minutes after the completion of step 2, the gauge pressure of the spray gun is 0.25MPa, the horizontal movement speed of the spray gun vertical to the sample surface is 2cm/s, and the amount of the hydrophobic paint is 10L/㎡;

(4) Heating and curing: The sample was cured at 200ºC for 2 hours, and the superhydrophobic coating was prepared after cooling.

The obtained composite coating did not fall off in the cross-cut test, and the coating was uniformly combined with the substrate. The static contact angle of deionized water on the surface of the sample was measured by a VCA Optima contact angle meter from AST Company, and the droplet volume was 5 μL. At least 5 points were selected to collect data on each test surface, and the average value of the results could reach 153°, showing superhydrophobicity.

Example 4

The aluminum alloy with the size of 20mm×40mm×10mm is used as the base material. The composition of the binder is configured according to the volume ratio of γ-glycidyl ether oxypropyltrimethoxysilane: distilled water: ethanol 4:7:9, and it is allowed to stand for 30 minutes. Preparation method of hydrophobic coating: 1.5g/L of multi-walled carbon nanotubes with diameter of 0～50nm, 1.5g/L of silicon carbide powder with diameter of 0.5～0.7μm, 100mL/L of tetraethyl silicate, heptadecafluorodecyltrimethoxysilane The hydrolyzed solution was 80 mL/L, and ethanol was used as the solvent, and the mixture was stirred for 120 min. The heptafluorodecyltrimethoxysilane hydrolyzed solution is configured according to the volume ratio of heptadecafluorodecyltrimethoxysilane:distilled water:ethanol 20:1:79. The preparation process is as follows:

(1) Pre-treatment: Use 200 ~ 1000# sandpaper to polish the aluminum alloy surface, rinse and dry in sequence with tap distilled water;

(2) Spraying binder: the gauge pressure of the spray gun is 0.4MPa, the horizontal movement speed of the spray gun vertical to the surface of the sample is 3cm/s, and the amount of binder is 10L/㎡;

(3) Spraying the hydrophobic coating: 10 minutes after the completion of step 2, the gauge pressure of the spray gun is 0.4MPa, the horizontal movement speed of the spray gun vertical to the surface of the sample is 3cm/s, and the amount of the hydrophobic coating is 10L/㎡;

(4) Heating and curing: The sample was cured at 200ºC for 2 hours, and the superhydrophobic coating was prepared after cooling.

The obtained composite coating did not fall off in the cross-cut test, and the coating was uniformly combined with the substrate. The static contact angle of deionized water on the surface of the sample was measured by a VCA Optima contact angle meter from AST Company, and the droplet volume was 5 μL. At least 5 points were selected to collect data on each test surface, and the average value of the results could reach 153°, showing superhydrophobicity.

It should be emphasized that the embodiments of the present invention are not limited by the above-mentioned examples, and any other changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be equivalent The replacement modes are all included within the protection scope of the present invention.

Claims (6)

1. a super-hydrophobic coating of high binding force, is characterized in that, comprises binding agent and hydrophobic coating: The volume ratio of the binder raw materials is as follows: the binder is configured according to the volume ratio of γ-glycidyl ether oxypropyltrimethoxysilane: distilled water: ethanol from 2:1:9 to 4:7:9; The volume ratio of the raw materials for the hydrophobic coating is: 1.5-3 g/L of multi-walled carbon nanotubes with a diameter of 0-50 nm, 1-4 g/L of silicon carbide powder with a diameter of 0.5-0.7 μm, and 40-100 mL/L of tetraethyl silicate. , Heptadecafluorodecyl trimethoxysilane hydrolyzate 20～80mL/L, ethanol is used as solvent. 2. a kind of high binding force super-hydrophobic coating according to claim 1, is characterized in that, described heptafluorodecyltrimethoxysilane hydrolyzate preparation method is: by heptafluorodecyltrimethoxysilane : Distilled water: ethanol volume ratio 1:1:98 to 20:1:79 configuration. 3. a kind of high binding force super-hydrophobic coating according to claim 1, is characterized in that, after described hydrophobic coating is configured, ultrasonic treatment is carried out 0～60min first and then stirring treatment is 0～120min. 4. the preparation method of a kind of high binding force super-hydrophobic coating described in any one of claim 1-3, is characterized in that, comprises the steps: (1) Surface finishing of the metal substrate; (2) Spray 2~10L/㎡ of adhesive to the substrate of step (1); (3) Spray 10~20L/㎡ of hydrophobic paint on the substrate of step (2); (4) Heating and curing: the substrate in step (3) is cured at 120-200ºC for 2-16 hours, and the superhydrophobic coating is prepared after cooling. 5 . The method for preparing a high-binding superhydrophobic coating according to claim 4 , wherein step (3) is performed 1 to 10 minutes after the step (2) is completed. 6 . 6 . The method for preparing a high-binding superhydrophobic coating according to claim 4 , wherein the spray gun gauge pressure of the spraying described in steps (2) and (3) is 0.25-0.40 MPa, and the spray gun is vertically positioned. 7 . The horizontal movement speed of the surface of the base workpiece is 1~3cm/s.