CN108587262B - Corrosion-resistant antifouling coating and preparation method thereof - Google Patents

Abstract

The invention discloses a corrosion-resistant antifouling coating and a preparation method thereof, and the corrosion-resistant antifouling coating comprises the following raw materials in percentage by weight: 10-30% of a binder; 1-10% of a passivating agent; 20-50% of corrosion-resistant functional filler; 20-50% of photocatalytic functional filler; the binder is selected from aluminum dihydrogen phosphate aqueous solution; the passivating agent is selected from at least one of chromium oxide, sodium tungstate and sodium silicate; the corrosion-resistant functional filler is selected from aluminum powder and/or zinc powder; the photocatalytic functional filler is selected from metal-doped nano titanium dioxide or pure nano titanium dioxide. The corrosion-resistant antifouling coating is prepared by mixing the raw materials with water, coating, heating and curing. The invention discloses a corrosion-resistant antifouling coating, which endows the coating with a good antifouling function under the condition of not losing the corrosion resistance of the coating and further expands the application field of the coating.

Description

A kind of anti-corrosion and anti-fouling coating and preparation method thereof

technical field

The invention relates to the technical field of functional coating protection, in particular to a corrosion-resistant and anti-fouling coating and a preparation method thereof.

Background technique

The marine environment is one of the most severe environments for metal corrosion under natural conditions. Seawater is a strong dielectric solution. Combined with the combined effects of multiple corrosive environments such as freezing and thawing, sea fog, typhoons, rainstorms, and industrial emissions, marine corrosion phenomenon. It is estimated that 1.5 tons of steel is corroded every second in the steel soaked in the ocean in my country. Therefore, there are many studies on corrosion-resistant coatings for offshore equipment. Offshore engineering equipment is not only corroded by seawater, but also adhered by various marine organisms (such as shellfish, seaweed, seaweed, etc.) and other pollutants. Oil and gas pipelines, submarine optical cables and other facilities. Biofouling tends to accelerate corrosion phenomena. Therefore, the biggest problem facing the safe use of marine equipment, especially marine components, is how to reduce the marine biofouling problem on its surface.

At present, the common ways to slow down the occurrence of marine biofouling on the surface of materials are applying antifouling paint, adding poisonous materials to seawater, electrolytic antifouling, and physical methods such as filtration, scorching, and ultrasonic waves. Among them, the most used antifouling coatings. There is an urgent need for an antifouling coating that is resistant to both seawater corrosion and biofouling while causing as little pollution to the ocean as possible.

Biofouling is a biological hazard that people encounter only after they have started to engage in maritime activities, and the process is entirely a natural phenomenon. The formation of fouling biological community is a typical ecological succession process, which can be roughly divided into three stages. (1) Early stage: bacteria and diatoms secrete mucus to form microbial mucosa on the surface of clean objects in the sea; (2) Middle stage: larvae of large fouling organisms begin to attach, the species and number of individuals continue to increase, and the size and quality of the community continue to increase. (3) Stable stage: species with long growth period and large individuals fully grow, displacing or covering some already attached medium and Small species, the community species composition is more complex and the quality is large, and its structure will not change significantly over time.

Harnessing the photocatalytic function of photocatalytic materials as marine antifouling coatings is a new area of research. Photocatalytic materials have been widely used in environmental protection, sterilization, air purification and other fields, of which titanium dioxide is the most widely used. The working principle of photocatalytic materials: if they are irradiated by sunlight or fluorescent lamps with energy greater than their forbidden band width, electrons (e ^- ) in the valence band will be excited to the conduction band, and corresponding holes ( h ⁺ ), negatively charged electrons and positively charged holes react with H ₂ O and O ₂ adsorbed on the semiconductor surface to generate active groups such as ·O ^-2 , ·OH, etc., which have strong oxidative decomposition Therefore, it can decompose, remove and kill various organic substances, microorganisms, etc. attached to the surface of the photocatalytic material. Therefore, it is feasible to use photocatalytic technology to realize the antifouling function of marine structures. It is of great significance to develop coatings with both corrosion resistance and photocatalytic function for application in marine components, road administration and other harsh working conditions, and will generate huge social and economic benefits.

SUMMARY OF THE INVENTION

The invention discloses an anti-corrosion and anti-fouling coating, which can endow the coating with good anti-fouling function and further expand its application field without losing the anti-corrosion performance of the coating.

The specific technical solutions are as follows:

A kind of anti-corrosion and anti-fouling coating, by weight percentage, the raw material composition comprises:

Described binder is selected from aluminum dihydrogen phosphate aqueous solution;

Described passivating agent is selected from at least one in chromium oxide, sodium tungstate, sodium silicate;

The corrosion-resistant functional filler is selected from aluminum powder and/or zinc powder;

The photocatalytic functional filler is selected from metal-doped nano-titanium dioxide or pure nano-titanium dioxide.

Preferably:

The concentration of the aluminum dihydrogen phosphate aqueous solution is 30-50wt%;

The corrosion-resistant functional filler is spherical, and the particle size is 500 nm to 5 μm;

The metal-doped nano-titanium dioxide is selected from silver-doped nano-titanium dioxide, and the titanium dioxide crystal form in the silver-doped nano-titanium dioxide or pure nano-titanium dioxide includes anatase phase nano-titanium dioxide, and the particle size is 5-100 nm.

Further preferably, the corrosion-resistant and anti-fouling coating, by weight percentage, the raw material composition includes:

Further preferably, the particle size of the corrosion-resistant functional filler is 2 μm, the particle size of the photocatalytic functional filler is 5-25 nm, and the mass ratio of the corrosion-resistant functional filler to the photocatalytic functional filler is 0.66-1.25:1.

The invention also discloses the preparation method of the corrosion-resistant and anti-fouling coating, and the specific steps include:

(1) Weigh the binder, passivation agent, corrosion-resistant functional filler and photocatalytic functional filler according to the mass ratio, and then blend with deionized water, and mix uniformly to obtain a raw material solution;

(2) Coating the raw material liquid on the surface of the pretreated substrate, and then heating and curing to obtain the anti-corrosion and anti-fouling coating.

In step (1):

Preferably, in the raw material liquid, the mass ratio of the binder to the deionized water is 100-150:100;

The mixing method is high-speed stirring, the rotating speed is 800-1000r/min, and the time is 0.5-2h.

In step (2):

Preferably, the substrate is selected from low carbon steel, stainless steel, 45 gauge steel or cast iron;

The pretreatment includes oil removal, rust removal and roughening treatment, and the roughening methods include sandblasting, threading, knurling or electric roughening.

Preferably, the coating method includes aerosol spraying or brushing.

For the aerosol spraying, the process parameters are: air pressure 0.4-0.8Mpa, spraying distance 100-300mm, spray gun speed 10-300mm/s, and coating spraying times 5-20 times. Further preferably, the air pressure is 0.6-0.8 Mpa, the spraying distance is 200-300 mm, the spray gun speed is 100-200 mm/s, and the coating spraying times are 10-20 times.

Preferably, for the heating and curing, the temperature is 200-300° C. and the time is 0.5-3 h.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention innovatively adds nano-photocatalytic functional fillers of a specific size, and then is compounded with a corrosion-resistant functional filler of a specific size, and optimizes the dispersion effect of the powder filler in the coating system, without losing the corrosion resistance of the coating. In this case, it gives the coating a good anti-fouling function and further expands its application field.

(2) The preparation method of the anti-corrosion and anti-fouling coating disclosed in the present invention has the advantages of simple operation, high production efficiency, good safety and low cost.

Description of drawings

Fig. 1 is the preparation flow chart of the anti-corrosion and anti-fouling coating of the present invention, and the functional fillers in the figure include anti-corrosion functional fillers and photocatalytic functional fillers;

2 is a field emission scanning electron microscope image of the surface and cross-section of the anti-corrosion and anti-fouling coating prepared in Example 1, (a) is the surface micro-morphology, (b) is the cross-section micro-morphology;

Figure 3 is a comparison photo of the anti-corrosion and anti-fouling coating prepared in Example 1 and the low carbon steel in the 2000h neutral salt spray resistance test, Figure (a) is the anti-corrosion and anti-fouling coating, Figure (b) is the control group Low carbon steel substrate;

Fig. 4 is the graph of the corrosion-resistant and anti-fouling coating degrading methylene blue solution prepared in Example 1;

Figure 5 is a scanning electron microscope image of the anti-corrosion and anti-fouling coating prepared in Example 1 and Bacillus after co-cultivation for 24 hours, Figure (a) is the anti-corrosion and anti-fouling coating, Figure (b) is the control group with low carbon steel.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, but do not have any limiting effect on it.

Example 1

(1) Preparation of inorganic corrosion-resistant and anti-fouling raw materials:

Choose 30wt% aluminum dihydrogen phosphate aqueous solution (60g) as binder, chromium oxide (13g) as passivator, aluminum powder (particle size 2μm, 100g) as corrosion-resistant functional filler and P25 powder (particle size 25nm, 80g) ) is a photocatalytic functional filler, added to 50ml of deionized water, and stirred at a high speed for 0.5h (rotation speed 1000r/min), so that each component of the raw material is uniformly dispersed and compounded.

(2) Substrate pretreatment: Degrease and derust the surface of the low carbon steel of the substrate material, and perform sandblasting treatment on the surface.

(3) Coating preparation: A layer of 100 μm inorganic anti-corrosion and anti-fouling coating was prepared on the surface of the pretreated substrate by aerosol spraying, and then heated and cured. Among them, the aerosol spraying parameters are air pressure of 0.6Mpa, spraying distance of 200mm, spray gun speed of 200mm/s, and spraying times of 10 times; curing parameters are 250°C for 1h.

Performance testing and characterization:

1. Coating morphology characterization

Observation of surface microscopic morphology: The coating sample prepared in this example was placed in a deionized aqueous solution for ultrasonic treatment for 30 min, then dried at 80 °C, and finally sprayed with Au on the surface, and the surface microscopic morphology was observed by field emission scanning electron microscope (FESEM). appearance.

Observation of the microscopic morphology of the cross section: the prepared samples were ground and polished with 400#, 800#, 1200#, 1500#, 2000# sandpaper in turn, then placed in deionized aqueous solution for ultrasonic treatment for 5 minutes, dried, and finally sprayed with Au on the surface. The microscopic morphology of the cross section was observed by field emission scanning electron microscope.

The field emission scanning electron microscope image shows that the coating is continuous and dense in structure ((a) in Figure 2). Further observation of the cross-sectional morphology shows that the thickness of the coating is 100 μm ((b) in Figure 2).

2. Corrosion resistance test

The coating prepared in this example is tested by neutral salt spray test, according to the standard ISO 9227:1990 "Artificial Atmosphere Corrosion Test-Salt Spray Test":

According to the standard requirements, the test uses chemically pure NaCl solution prepared with deionized water, the concentration is 50±5g/L, and the pH value of the solution is adjusted with hydrochloric acid or sodium hydroxide to ensure that the range is between 6.5 and 7.2. The density of the configured NaCl solution is in the range of 1.0255 to 1.0400 g/cm ³ , the size of the salt spray test sample is 30mm×20mm×3mm, and the salt spray test procedure is as follows: (a) The corrosion resistance of the carbon-containing fiber of the present invention is sprayed on. The ground-coated samples and the unsprayed samples (low carbon steel) were first cleaned with detergent, then soaked in clean water, and finally placed in anhydrous ethanol to be cleaned with an ultrasonic cleaner, and the edges were sealed with hot glue; (b ) Take out the experimental sample to air dry for 1 hour, then rinse it with running water, and finally dry it with a hair dryer; (c) Place the sample on a standard plastic bracket with an angle of 45°; (d) The salt spray test cycle is based on The tested samples are determined, the intermediate inspection is once every 12 hours, and the sample taking frequency is the same as the test period; (e) the temperature in the salt spray box is 35±2℃, and the spray air pressure is 1kgf/cm ² . By adjusting the speed of salt spray deposition, After 24 hours of spraying, the rate is 1-2 ml/h per 80 cm ² area; (f) The corrosion morphology of the salt spray test sample was observed by a digital camera.

The results of the salt spray test show that the samples of the inorganic corrosion-resistant photocatalytic coating prepared in this example can withstand the neutral salt spray test for 2000 hours, and no substrate corrosion occurs.

3. Photocatalytic performance test

The performance test of degrading methylene blue solution is carried out to the coating prepared in this example:

A methylene blue solution with a concentration of 5 ppm was prepared, and 30 ml was placed in a petri dish with a diameter of 9 cm. The nano- _TiO coating with a size of 4 × 4 cm was placed in a petri dish and shaken with a shaker speed of 60 r/min. After 1 hour in the dark, the UV lamp was turned on for UV illumination. The power of the UV lamp was 15W, the wavelength was 365nm, and the distance between the sample and the UV lamp was 15cm. At 0h, 0.5h, 1.5h, 2.5h, 3.5h, 4.5h, and 5.5h after the UV lamp was turned on, extract 200 μl of methylene blue solution from the petri dish with a pipette, and place it in a 96-well plate for absorbance testing. Record test results. The concentration of methylene blue in the solution was calculated from the absorbance value at a wavelength of 664 nm. The purpose of keeping the coating in the dark for 1 hour is to make the coating fully contact with the methylene blue solution. At least 3 experiments should be performed for each group of samples to reduce errors.

The test results show that the coating prepared in this example exhibits good photocatalytic function, and the degradation rate of the methylene blue solution can reach more than 80% after 5.5 hours.

4. Anti-fouling performance test

The coating prepared in this example was mixed with Bacillus (Bacillus is a typical Gram-positive bacteria, because Bacillus is a unique bacteria in the ocean) for 24 hours, and the sticking of Bacillus was observed. Attached.

The samples were ultrasonically cleaned in deionized water for 5 min, dried in flowing air, and then sterilized under UV light for 2 h. Put the sterilized samples into a 6-well plate, add 3 mL of bacterial liquid with a concentration of 10 ⁸ CFU/mL into each well, and label them well, and put them into a shaking incubator (temperature 25°C, rotating speed 120 rpm) for culture. 24h. After 24 hours of incubation, the bacterial liquid was sucked out using a pipette gun, and the unattached bacteria on the surface of the sample were washed away from the side of the sample with artificial seawater, immersed twice, and then treated with a 2.5% glutaraldehyde seawater solution to the attached bacteria. Bacteria were fixed and stored in a refrigerator at 4°C for 24h. The glutaraldehyde was sucked out with a pipette, rinsed twice with artificial seawater, and then immersed in alcohol aqueous solutions of different concentrations for dehydration (25%, 50%, 75%, 90% and 100%). Finally, the samples were placed in an incubator at 37 °C to dry for 24 h, and the adhesion of the samples was observed after spraying gold.

The test results show that the coatings prepared in this example show good anti-fouling performance. Compared with the low carbon steel in the control group (that is, the low carbon steel substrate without The amount of Bacillus adhering to the layer surface was reduced by about 80%.

Comparative Example 1

The preparation process is basically the same as that in Example 1, except that no photocatalytic functional filler is added during the preparation of the raw materials.

After testing, the coating prepared in this comparative example has good corrosion resistance, and no obvious corrosion occurred after 2000h of neutral salt spray test, but its anti-fouling performance is average. The amount did not decrease significantly.

Comparative Example 2

The preparation process is basically the same as that in Example 1, except that the photocatalytic functional filler added during the preparation of the raw materials is pure rutile phase TiO ₂ with a particle size of 20 nm.

After testing, the coating prepared in this comparative example has good corrosion resistance, and no obvious corrosion occurs after 2000 hours of neutral salt spray test; the photocatalytic performance of the coating is poor, and the degradation rate of methylene blue solution is about 50% after 5.5 hours; With anti-fouling function, compared with the low carbon steel surface of the control group, the adhesion amount of Bacillus did not decrease significantly.

Comparative Example 3

The preparation process is basically the same as that in Example 1, except that the corrosion-resistant functional filler added during the preparation of the raw materials is Ni60 powder, and the particle size is 40 μm.

After testing, the coating prepared by this comparative example has poor corrosion resistance, and obvious corrosion products can be seen after 100 hours of neutral salt spray test; the photocatalytic performance of the coating is good, and the degradation rate of methylene blue solution is about 70% after 5.5 hours; The anti-fouling function is average, and the amount of Bacillus adherence is reduced by about 50% compared with the control group mild steel surface.

Example 2

(1) Preparation of inorganic corrosion-resistant and anti-fouling raw materials:

Select 30wt% aluminum dihydrogen phosphate aqueous solution (60g) as binder, sodium silicate (20g) as passivator, aluminum powder (particle size 2μm, 80g) as corrosion-resistant functional filler, P25 powder (particle size 25nm, 120g) is a photocatalytic functional filler, added to 50ml of deionized water, and stirred at high speed for 1h (rotation speed 1000r/min), so that each component of the raw material is uniformly dispersed and compounded.

(2) Substrate pretreatment: degreasing and rust removal are performed on the surface of the substrate material, and sandblasting is performed on the surface.

(3) Coating preparation: A layer of 200 μm inorganic anti-corrosion and anti-fouling coating was prepared on the surface of the pretreated substrate by aerosol spraying, and then heated and cured. Among them, the parameters of aerosol spraying are air pressure of 0.8Mpa, spraying distance of 300mm, spray gun speed of 100mm/s, and spraying times of 20 times; curing parameters are 300°C for 2h.

Performance testing and characterization:

1. Coating morphology characterization

The test process is the same as that of Example 1. The microscopic morphology of the coating is observed by a field emission scanning electron microscope (FESEM), and it can be seen that the coating is continuous and dense in structure, and the coating thickness is 200 μm.

2. Corrosion resistance test

The test process is the same as that of Example 1. The results show that the coating sample of this example can withstand the neutral salt spray test for 2000 hours, and achieves excellent protection function for the substrate.

3. Photocatalytic performance test

The test process is the same as that of Example 1. The results show that the coating sample of this example exhibits good photocatalytic function. After 5.5 hours, the degradation rate of the methylene blue solution can reach 82%.

4. Anti-fouling performance test

The test process is the same as that of Example 1. The results show that the coating samples of this example have good antifouling performance. Compared with the low carbon steel of the control group, the adhesion amount of Bacillus on the surface of the coating prepared in this example is reduced by about 88%.

Example 3

(1) Preparation of inorganic corrosion-resistant and anti-fouling raw materials:

Choose 30wt% aluminum dihydrogen phosphate aqueous solution (55g) as binder, sodium silicate (15g) as passivator, zinc powder (particle size is 2μm, 100g) as corrosion-resistant functional filler, Ag-doped anatase phase TiO ₂ powder (particle size 5-10nm, 80g) is a photocatalytic functional filler, added to 50ml of deionized water, and stirred at high speed for 1.5h (rotation speed 800r/min), so that each component of the raw material is uniformly dispersed and compounded.

(2) Substrate pretreatment: degreasing and rust removal are performed on the surface of the substrate material, and sandblasting is performed on the surface.

(3) Coating preparation: The inorganic anti-corrosion and anti-fouling coating with a thickness of 60 μm was prepared on the surface of the pretreated substrate by brushing with a brushing roller, and heated and cured. Among them, the single brushing thickness of the brushing roller was 20 μm, and the brushing was performed three times; the curing parameter was 250 °C for 2 h.

Performance testing and characterization:

1. Coating morphology characterization

The test process is the same as that of Example 1, and the microscopic morphology of the coating is observed by a field emission scanning electron microscope (FESEM), and it can be seen that the coating is continuous and dense in structure, and the coating thickness is 60 μm.

2. Corrosion resistance test

The test process is the same as that of Example 1. The results show that the coating sample of this example can withstand the neutral salt spray test for 2000 hours, and achieves excellent protection function for the substrate.

3. Photocatalytic performance test

The test process is the same as that of Example 1. The results show that the coating sample of this example exhibits a good photocatalytic function. After 5.5 hours, the degradation rate of the methylene blue solution can reach 85%.

4. Anti-fouling performance test

The test process is the same as that of Example 1. The results show that the coating samples of this example have good antifouling performance. Compared with the low carbon steel of the control group, the adhesion amount of Bacillus on the surface of the coating prepared in this example is reduced by about 82%.

Example 4

(1) Preparation of inorganic corrosion-resistant and anti-fouling raw materials:

30wt% aluminum dihydrogen phosphate aqueous solution (60g) was selected as binder, sodium tungstate (10g) as passivator, aluminum powder (particle size 2μm, 80g) as corrosion-resistant functional filler, pure anatase phase _TiO2 Powder (particle size 5-10nm, 80g) is a photocatalytic functional filler, added to 50ml of deionized water, and stirred at high speed for 1h (rotation speed 1000r/min), so that each component of the raw material is uniformly dispersed and compounded.

(2) Substrate pretreatment: degreasing and rust removal are performed on the surface of the substrate material, and sandblasting is performed on the surface.

(3) Coating preparation: use a brushing roller to paint, prepare a 60 μm inorganic anti-corrosion and anti-fouling coating on the surface of the pretreated substrate, and heat and cure it. Among them, the single brushing thickness of the brushing roller is 20 μm, and the brushing is performed three times; the curing parameter is 250 °C for 0.5 h.

Performance testing and characterization:

1. Coating morphology characterization

The test process is the same as that of Example 1, and the microscopic morphology of the coating is observed by a field emission scanning electron microscope (FESEM), and it can be seen that the coating is continuous and dense in structure, and the coating thickness is 60 μm.

2. Corrosion resistance test

The test process is the same as that of Example 1. The results show that the coating sample of this example can withstand the neutral salt spray test for 2000 hours, and achieves excellent protection function for the substrate.

3. Photocatalytic performance test

The test process is the same as that of Example 1. The results show that the coating sample of this example exhibits a good photocatalytic function. After 5.5 hours, the degradation rate of the methylene blue solution can reach 75%.

4. Anti-fouling performance test

The test process is the same as that of Example 1. The results show that the coating sample of this example has good antifouling performance. Compared with the low carbon steel of the control group, the adhesion amount of Bacillus on the surface of the coating prepared in this example is reduced by about 70%.

Claims (9)

1. The corrosion-resistant antifouling coating is characterized by comprising the following raw materials in percentage by weight:

the binder is selected from aluminum dihydrogen phosphate aqueous solution;

the passivating agent is selected from at least one of chromium oxide, sodium tungstate and sodium silicate;

the corrosion-resistant functional filler is selected from aluminum powder and/or zinc powder;

the photocatalytic functional filler is selected from metal-doped nano titanium dioxide or pure nano titanium dioxide; the metal-doped nano titanium dioxide or the pure nano titanium dioxide comprises anatase phase nano titanium dioxide; the particle size of the photocatalytic functional filler is 5-25 nm;

the mass ratio of the corrosion-resistant functional filler to the photocatalytic functional filler is 0.66-1.25: 1.

2. the corrosion-resistant antifouling coating according to claim 1, wherein:

the concentration of the aluminum dihydrogen phosphate aqueous solution is 30-50 wt%;

the size of the corrosion-resistant functional filler is 500 nm-5 mu m;

the metal-doped nano titanium dioxide is selected from silver-doped nano titanium dioxide.

3. The corrosion-resistant and stain-resistant coating according to claim 1 or 2, wherein the coating comprises the following raw materials in percentage by weight:

4. the preparation method of the corrosion-resistant antifouling coating according to any one of claims 1 to 3, characterized by comprising the following steps:

(1) weighing the binder, the passivating agent, the corrosion-resistant functional filler and the photocatalytic functional filler according to the mass ratio, blending the weighed materials with deionized water, and uniformly mixing to obtain a raw material solution;

(2) and coating the raw material liquid on the surface of a pretreated substrate, and heating and curing to obtain the corrosion-resistant antifouling coating.

5. The method for preparing the corrosion-resistant and stain-resistant coating according to claim 4, wherein in the step (1), the mass ratio of the binder to the deionized water in the raw material liquid is 100-150: 100, respectively;

the mixing mode is high-speed stirring, the rotating speed is 800-1000 r/min, and the time is 0.5-2 h.

6. The method for preparing corrosion-resistant and stain-resistant coating according to claim 4, wherein in the step (2), the substrate is selected from mild steel, stainless steel, No. 45 steel or cast iron;

and the pretreatment comprises oil removal, rust removal and coarsening treatment.

7. The method for preparing the corrosion-resistant and stain-resistant coating according to claim 4, wherein in the step (2), the coating manner comprises aerosol spraying or brush coating.

8. The method for preparing the corrosion-resistant antifouling coating according to claim 7, wherein the aerosol spraying comprises the following process parameters: the air pressure is 0.4-0.8 Mpa, the spraying distance is 100-300 mm, the speed of the spray gun is 10-300 mm/s, and the spraying times of the coating are 5-20 times.

9. The method for preparing the corrosion-resistant and stain-resistant coating according to claim 4, wherein in the step (2), the heating and curing are carried out at a temperature of 200-300 ℃ for 0.5-3 h.

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