Environment-friendly antibacterial color steel plate and preparation process thereof

Abstract

The invention relates to the technical field of color-coated plates, in particular to an environment-friendly antibacterial color steel plate and a preparation process thereof. According to the method, sand blasting treatment is combined with nano zinc oxide and iron oxide solution soaking, so that the surface adhesive force and corrosion resistance of the steel plate are enhanced; the clinoptilolite composite filler is subjected to ball milling, sheared and premixed with ethanol at a high speed, then uniformly mixed and stirred with other components, and filtered, so that the quality of the coating is ensured; the clinoptilolite composite filler has good ion exchange capacity and can continuously release metal ions with an antibacterial effect, and the metal ions can destroy cell membranes of bacteria and inhibit growth and reproduction of the bacteria, so that the antibacterial effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of color-coated plates, and in particular to an environmentally friendly antibacterial color-coated steel plate and a preparation process thereof. Background Art

[0002] Color-coated steel, also known as pre-painted steel, is a type of steel plate with an organic coating. It offers advantages such as excellent corrosion resistance, vibrant colors, attractive appearance, ease of processing, and inherent strength at a lower cost. Color-coated steel plate is generally available in several types, with fluorocarbon-coated plate being the highest-grade. Color-coated steel plate is typically distributed from steel mills in rolls for easy transportation and subsequent processing. The substrates for color-coated steel plate include cold-rolled, hot-dip galvanized, and electrogalvanized. Coating types include polyester, silicone-modified polyester, polyvinylidene fluoride, and plastisol.

[0003] In environments with strict sanitation requirements, bacteria and mold can easily grow on the surface of materials. Color-coated steel sheets with antibacterial properties can effectively inhibit the growth of microorganisms, reducing the risk of disease transmission. Patent application number CN108893035A proposes a method for preparing color-coated steel sheets with antibacterial and purification functions. The effective antibacterial component in the color-coated steel sheets prepared in this application is a silver-modified nano-titanium dioxide composite antibacterial powder. The silver ions and nano-titanium dioxide provide bactericidal and antibacterial properties, while the titanium dioxide photocatalyzes the decomposition of harmful gases such as formaldehyde, benzene, toluene, xylene, and TVOC. However, the silver ions used in this method are relatively environmentally friendly and are prone to potential environmental impacts. Furthermore, the preparation process is relatively complex, requiring multiple surface modification treatments of the nano-titanium dioxide, which increases production costs and reduces production efficiency. Therefore, the present invention provides an environmentally friendly antibacterial color-coated steel sheet and its preparation process to address the above issues. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide an environmentally friendly antibacterial color steel plate and a preparation process thereof.

[0005] Disclosed is an environmentally friendly antibacterial color steel plate, comprising a steel plate and a base layer and a surface layer arranged on the steel plate. The primer used for the base layer comprises the following raw materials by mass percentage: 15-25% polyester resin, 8-16% clinoptilolite composite filler, 5-12% crosslinking agent, 40-50% solvent, 1-2% dispersant, 0.5-1% leveling agent and 1-2% anti-settling agent; the topcoat used for the surface layer comprises the following raw materials by mass percentage: 25-35% polyester resin, 10-15% pigment, 8-16% clinoptilolite composite filler, 8-18% crosslinking agent, 40-50% solvent, 1-2% dispersant, 0.5-1% leveling agent and 1-2% anti-settling agent.

[0006] Preferably, the solvents are all propylene glycol methyl ether acetate, and the polyester resins are all non-crystalline polyester resins.

[0007] A preparation process of an environmentally friendly antibacterial color steel plate comprises the following steps:

[0008] Step 1: Fix the steel plate on the workbench of the sandblasting equipment, use corundum or glass beads with a particle size of 80-120 mesh as the abrasive, adjust the sandblasting pressure to 0.4-0.6MPa, and sandblast the surface of the steel plate for 1-3 minutes. Then immerse the sandblasted steel plate in a solution containing nano zinc oxide and iron oxide for 2-5 minutes to allow the nano materials to be evenly adsorbed on the surface of the steel plate;

[0009] Step 2: Apply the primer evenly on the surface of the steel plate, controlling the coating thickness to 15-25 μm; place the coated steel plate in a microwave-assisted oven and bake it at 120-150°C for 20-40 seconds to quickly cure the primer and form a solid base layer;

[0010] Step 3: Apply the topcoat evenly on the primer layer, controlling the coating thickness to 10-20 μm; place the coated steel plate in an oven at 160-180°C for 1-5 minutes;

[0011] Step 4: Allow the cured color-coated steel plate to cool naturally to room temperature for inspection.

[0012] Preferably, the preparation method of the primer is specifically as follows: the polyester resin and the solvent are mixed and stirred evenly to form a base resin solution; the clinoptilolite composite filler is ball-milled to a particle size of 5-10 μm, and premixed with ethanol at a high-speed shear of 3000 rpm for 10 minutes to form a premix, a polymer dispersant is added to the premix and mixed and dispersed evenly to form a suspension, which is slowly added to the base resin solution and mixed evenly; an organosilicon leveling agent, an organic bentonite anti-settling agent and an amino resin crosslinker are added in sequence and stirred continuously until completely uniform; impurities and large particles are filtered using a filter to remove them to prepare the primer.

[0013] Preferably, the method for preparing the topcoat specifically comprises the following steps:

[0014] a. Mix the polyester resin and the solvent and stir to form a base resin solution;

[0015] b. The pigment and polymer dispersant are mixed and stirred using a high-speed disperser for 10 minutes to form a pigment dispersion;

[0016] c. The clinoptilolite composite filler was ball-milled to a particle size of 5-10 μm and premixed with ethanol at 3000 rpm for 10 minutes under high shear to form a premix;

[0017] d. Mix the premix and pigment dispersion to form a suspension, slowly add it to the base resin solution and stir evenly;

[0018] e. Add silicone leveling agent, organic bentonite anti-settling agent, and amino resin crosslinker in sequence, and continue stirring until completely uniform;

[0019] f. Use a filter to remove impurities and large particles to obtain the topcoat.

[0020] Preferably, the preparation method of the clinoptilolite composite filler is:

[0021] (1) Preparation of zeolite gel: Sodium silicate and aluminum oxide were dissolved in sodium hydroxide solution, tetraethylammonium hydroxide was added, and the mixture was stirred to form a transparent gel. The mixture was aged at 80°C for 24 h, transferred to an autoclave, and crystallized at 160°C for 24 h. The mixture was filtered and washed with deionized water until neutral to obtain clinoptilolite gel.

[0022] (2) Drying and sintering: The clinoptilolite gel was rinsed with anhydrous ethanol, dried at 120°C for 6 hours, placed in a muffle furnace, and calcined at 250°C for 4 hours to obtain a clinoptilolite composite filler.

[0023] Preferably, the primer and topcoat are both applied by electrostatic spraying.

[0024] The beneficial effects achieved by the present invention are:

[0025] 1. The clinoptilolite composite filler in the present invention has good ion exchange capacity and can continuously release metal ions with antibacterial effects. These metal ions can destroy bacterial cell membranes and inhibit bacterial growth and reproduction. Nano-zinc oxide can produce strong oxidizing substances under ultraviolet light irradiation. These active oxygen species can destroy bacterial cell structures, thereby achieving antibacterial effects. In addition, the preparation process of the clinoptilolite composite filler is simple, the cost is low, and it is easy to industrialize.

[0026] 2. Both the primer and the topcoat of the present invention use propylene glycol methyl ether acetate as a solvent, which can significantly reduce the emission of volatile organic compounds (VOCs) and meet environmental protection requirements. At the same time, through the sandblasting process, using corundum or glass beads as abrasives, it can effectively remove rust, oxide scale, stains and other impurities on the surface of the steel plate, making the surface of the steel plate rough and clean, creating good conditions for the adhesion of subsequent coatings, and enhancing the bonding force between the coating and the steel plate. The sandblasted steel plate is immersed in a solution containing nano zinc oxide and iron oxide. The nano materials are uniformly adsorbed on the surface of the steel plate to form a nano-scale protective film. This protective film can further improve the corrosion resistance and wear resistance of the steel plate surface, while providing a more uniform base for the application of the primer, which helps to improve the overall performance of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of the process for preparing the environmentally friendly antibacterial color-coated steel plate used in Examples 1-3 of the present invention;

[0028] Figure 2 This is a flow chart of the preparation method of the clinoptilolite composite filler used in Examples 1-3 of the present invention;

[0029] Figure 3 The adhesion, hardness, impact strength, bending test, and wear resistance test results of the environmentally friendly antibacterial color steel plates prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention are shown;

[0030] Figure 4 These are the test results of salt spray resistance, aging performance, antibacterial performance, and photocatalytic performance of the environmentally friendly antibacterial color-coated steel plates prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to specific embodiments.

[0032] In the following examples, the preparation method of the primer is as follows:

[0033] The polyester resin and the solvent are mixed and stirred to form a base resin solution; the clinoptilolite composite filler is ball-milled to a particle size of 5-10 μm, and premixed with ethanol at 3000 rpm for 10 minutes to form a premix; a polymer dispersant is added to the premix and mixed and dispersed evenly to form a suspension, which is slowly added to the base resin solution and mixed evenly; an organosilicon leveling agent, an organobentonite anti-settling agent, and an amino resin cross-linking agent are added in sequence and stirred continuously until completely uniform; and impurities and large particles are filtered through a filter to remove them to prepare a primer.

[0034] The preparation method of topcoat is:

[0035] a. Mix the polyester resin and the solvent and stir to form a base resin solution;

[0036] b. The pigment and polymer dispersant are mixed and stirred using a high-speed disperser for 10 minutes to form a pigment dispersion;

[0037] c. The clinoptilolite composite filler was ball-milled to a particle size of 5-10 μm and premixed with ethanol at 3000 rpm for 10 minutes under high shear to form a premix;

[0038] d. Mix the premix and pigment dispersion to form a suspension, slowly add it to the base resin solution and stir evenly;

[0039] e. Add silicone leveling agent, organic bentonite anti-settling agent, and amino resin crosslinker in sequence, and continue stirring until completely uniform;

[0040] f. Use a filter to remove impurities and large particles to obtain the topcoat.

[0041] The preparation method of the clinoptilolite composite filler is as follows:

[0042] (1) Preparation of zeolite gel: 15 parts by mass of sodium silicate and 7.5 parts by mass of aluminum oxide were dissolved in 300 parts by volume of deionized water, 25 parts by mass of sodium hydroxide were added, and the mixture was stirred until the solution became transparent. 2 parts by volume of tetraethylammonium hydroxide were added, and the mixture was stirred for 30 minutes to form a transparent gel. The mixture was aged at 80°C for 24 hours, transferred to an autoclave, and crystallized at 160°C for 24 hours. The mixture was filtered and washed with deionized water until neutral to obtain clinoptilolite gel.

[0043] (2) Drying and sintering: The clinoptilolite gel was rinsed with anhydrous ethanol, dried at 120°C for 6 hours, placed in a muffle furnace, and calcined at 250°C for 4 hours. The calcined material was then ball-milled and sieved to control the particle size to 10 μm, and premixed with ethanol at 3000 rpm for 10 minutes to obtain a clinoptilolite composite filler.

[0044] Example 1: A process for preparing an environmentally friendly antibacterial color steel plate, such as Figure 1 As shown, the following steps are included:

[0045] Step 1: Fix the steel plate on the workbench of the sandblasting equipment, use 120-mesh corundum as the abrasive, adjust the sandblasting pressure to 0.6 MPa, and sandblast the surface of the steel plate for 3 minutes. Then immerse the sandblasted steel plate in a solution containing nano-zinc oxide and iron oxide for 5 minutes to allow the nanomaterials to be evenly adsorbed on the surface of the steel plate.

[0046] Step 2: Apply the primer evenly on the surface of the steel plate and control the coating thickness to 25 μm; place the coated steel plate in a microwave-assisted oven and microwave-assisted bake at 150°C for 40 seconds to quickly cure the primer and form a solid base layer.

[0047] Step 3: Apply the topcoat evenly on the primer layer, controlling the coating thickness to 20 μm; place the coated steel plate in an oven and cure at 180°C for 5 minutes.

[0048] Step 4: Allow the cured color-coated steel plate to cool naturally to room temperature for inspection.

[0049] The primer comprises the following raw materials by mass percentage: 25% polyester resin (Vylon® 200), 16% clinoptilolite composite filler, 12% crosslinker (CYMEL 327), 40% solvent (propylene glycol methyl ether acetate), 2% dispersant (BYK-163), 1% leveling agent (BYK-333) and 2% anti-settling agent (organic bentonite);

[0050] The topcoat comprises the following raw materials by mass percentage: 35% polyester resin (Vylon® 200), 15% pigment (TDC51D+AZ), 16% clinoptilolite composite filler, 18% crosslinker (CYMEL® 325), 40% solvent (propylene glycol methyl ether acetate), 2% dispersant (BYK-163), 1% leveling agent (BYK-371) and 2% anti-settling agent (organic bentonite).

[0051] Example 2: A process for preparing an environmentally friendly antibacterial color steel plate, such as Figure 1 As shown, the following steps are included:

[0052] Step 1: Fix the steel plate on the workbench of the sandblasting equipment, use glass beads with a particle size of 100 mesh as abrasive, adjust the sandblasting pressure to 0.5 MPa, and sandblast the surface of the steel plate for 2 minutes. Then immerse the sandblasted steel plate in a solution containing nano zinc oxide and iron oxide for 3 minutes to allow the nano materials to be evenly adsorbed on the surface of the steel plate.

[0053] Step 2: Apply the primer evenly on the surface of the steel plate and control the coating thickness to 20 μm; place the coated steel plate in a microwave-assisted oven and microwave-assisted bake at 135°C for 30 seconds to quickly cure the primer and form a solid base layer.

[0054] Step 3: Apply the topcoat evenly on the primer layer, controlling the coating thickness to 15 μm; place the coated steel plate in an oven and cure at 170°C for 3 minutes.

[0055] Step 4: Allow the cured color-coated steel plate to cool naturally to room temperature for inspection.

[0056] The primer comprises the following raw materials by mass percentage: 22% polyester resin (Vylon® 200), 14% clinoptilolite composite filler, 10% crosslinker (CYMEL 327), 43% solvent (propylene glycol methyl ether acetate), 1.8% dispersant (BYK-163), 0.9% leveling agent (BYK-333) and 1.8% anti-settling agent (organic bentonite);

[0057] The topcoat comprises the following raw materials by mass percentage: 32% polyester resin (Vylon® 200), 13% pigment (TDC51D+AZ), 14% clinoptilolite composite filler, 15% crosslinker (CYMEL® 325), 43% solvent (propylene glycol methyl ether acetate), 1.8% dispersant (BYK-163), 0.9% leveling agent (BYK-371) and 1.8% anti-settling agent (organic bentonite).

[0058] Example 3: A process for preparing an environmentally friendly antibacterial color steel plate, such as Figure 1 As shown, the following steps are included:

[0059] Step 1: Fix the steel plate on the workbench of the sandblasting equipment, use 80-mesh corundum as the abrasive, adjust the sandblasting pressure to 0.4 MPa, and sandblast the surface of the steel plate for 1 minute. Then immerse the sandblasted steel plate in a solution containing nano-zinc oxide and iron oxide for 2 minutes to allow the nanomaterials to be evenly adsorbed on the surface of the steel plate.

[0060] Step 2: Apply the primer evenly on the surface of the steel plate and control the coating thickness to 15 μm; place the coated steel plate in a microwave-assisted oven and microwave-assisted bake at 120°C for 20 seconds to quickly cure the primer and form a solid base layer.

[0061] Step 3: Apply the topcoat evenly on the primer layer, controlling the coating thickness to 10 μm; place the coated steel plate in an oven and cure at 160°C for 1 minute.

[0062] Step 4: Allow the cured color-coated steel plate to cool naturally to room temperature for inspection.

[0063] The primer comprises the following raw materials by mass percentage: 20% polyester resin (Vylon® 200), 12% clinoptilolite composite filler, 8% crosslinker (CYMEL 327), 45% solvent (propylene glycol methyl ether acetate), 1.5% dispersant (BYK-163), 0.8% leveling agent (BYK-333) and 1.5% anti-settling agent (organic bentonite);

[0064] The topcoat comprises the following raw materials by mass percentage: 30% polyester resin (Vylon® 200), 12% pigment (TDC51D+AZ), 12% clinoptilolite composite filler, 10% crosslinker (CYMEL® 325), 45% solvent (propylene glycol methyl ether acetate), 1.5% dispersant (BYK-163), 0.8% leveling agent (BYK-371) and 1.5% anti-settling agent (organic bentonite).

[0065] Comparative Example 1: Compared with Example 2, the clinoptilolite composite filler in the primer and the topcoat was replaced with natural zeolite, and the other parameters were consistent with those in Example 2.

[0066] Comparative Example 2: Compared with Example 2, the clinoptilolite composite filler in the primer and the topcoat was replaced with a common filler, and the other parameters were the same as those in Example 2.

[0067] The environmentally friendly antibacterial color-coated steel plates prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to relevant performance tests;

[0068] 1. Adhesion test: According to ASTM D3359, use a cutting tool to make a grid pattern (cross cut) on the coating surface. Apply adhesive tape to the grid and press it flat with your fingers to ensure full contact. Quickly remove the tape and check for peeling of the coating. Evaluate the adhesion level (0-5, 5 is the best) based on the peeling area.

[0069] 2. Hardness test: According to ISO 15184, use a pencil hardness tester. Select pencils of different hardness (from softest to hardest). Place the pencil perpendicular to the coating surface. Apply the specified pressure (750g) and scratch the coating. Observe whether there are scratches on the coating. Record the maximum pencil hardness value that does not produce scratches.

[0070] 3. Impact strength test: According to ASTM D2794, fix the sample on the impact test bench with the coating facing upward. Use a 500g hammer to drop freely from a height of 50cm to hit the sample surface. Check whether the coating has cracks, peeling or other damage.

[0071] 4. Bending test: According to ISO 1519, fix the sample on the bending tester, set the bending angle, gradually increase the bending angle, observe whether the coating has cracks or peeling, and record the non-destructive state at the maximum bending angle (0-180°).

[0072] 5. Wear resistance test: According to ASTM D4060, fix the sample on the wear tester, use the specified wear medium (sandpaper), set the load of 1000g, the rotation speed of 75 rpm and 1000 cycles, perform the friction test, measure the wear amount of the coating, and evaluate the wear resistance.

[0073] 6. Salt spray resistance test: According to ASTM B117, place the sample in a salt spray test chamber and spray 5% sodium chloride solution continuously at the specified temperature (35±2℃). The test time is 96 hours. Take out the sample, check the corrosion condition, and record the time when corrosion begins.

[0074] 7. Aging performance test: According to ASTM G155, place the sample in an accelerated aging test chamber, set UV-B (313nm) ultraviolet radiation, temperature 60±3℃ and humidity 50±5%, test time 1000 hours, take out the sample, check the color change, gloss loss and other physical property changes, record the aging time and performance changes.

[0075] 8. Antibacterial performance test: According to ISO 22196, the sample was pre-cleaned with 70% ethanol and inoculated with target bacteria (Escherichia coli or Staphylococcus aureus) at a concentration of approximately 1×10 5 CFU / mL, use a pipette to evenly add 10 μL of bacterial suspension to the sample surface, place it in a constant temperature and humidity incubator, and culture it at a temperature of 37±1℃ and a humidity of 85±5% for 24 hours. After the incubation, use a cotton swab dipped in sterile saline to gently wipe the sample surface to collect residual bacteria. Dilute the collected bacterial suspension and spread it on the agar plate, place it in a 37℃ incubator and continue to culture for 24 hours. Count the colony forming units (CFU) on the agar plate and calculate the antibacterial rate.

[0076] 9. Photocatalytic performance test: According to JIS R 1702, the sample was pre-cleaned with 70% ethanol. A 20 mg / L methyl orange solution was used as an indicator of photocatalytic degradation. 5 mL of the methyl orange solution was added to a cuvette. The initial absorbance was measured using a spectrophotometer at a wavelength of 464 nm. The steel plate sample was placed horizontally in a sealed container. The methyl orange solution was poured into the bottom of the container to ensure that the sample was completely immersed. The container was placed under a UV light source. The UV light source was UV-A (365 nm) with an irradiation intensity of 10 mW / cm 2 , keep the illumination time for 4 hours, take samples to measure the absorbance value of the solution, and calculate the degradation efficiency.

[0077] The above performance test results are as follows Figure 3 and Figure 4 As shown, it can be seen that:

[0078] ① Adhesion and mechanical properties: The color-coated steel plates of Examples 1-3 all showed excellent coating adhesion. In contrast, the adhesion of Comparative Example 1, in which natural zeolite was used instead of the clinoptilolite composite filler, and Comparative Example 2, in which ordinary fillers were used instead, decreased.

[0079] In the impact strength, bending test, and wear resistance tests, Examples 1-3 exhibited excellent mechanical properties without cracking or peeling, whereas Comparative Examples 1 and 2 performed poorly in these tests, especially Comparative Example 2, which had significantly reduced mechanical properties due to the lack of a protective layer with a high specific surface area and porous structure of clinoptilolite.

[0080] ② Corrosion resistance and aging performance: Examples 1-3 all showed excellent corrosion resistance in the salt spray test, with no signs of corrosion for more than 96 hours, while Comparative Examples 1 and 2 had poor corrosion resistance, with corrosion beginning to occur after 72 hours and 48 hours, respectively.

[0081] In the aging performance test, the color and gloss of Examples 1-3 remained almost unchanged, showing good weather resistance, while Comparative Examples 1 and 2 showed varying degrees of discoloration. In particular, Comparative Example 2, in the absence of the protective layer formed by the clinoptilolite filler, showed significantly deteriorated aging performance.

[0082] ③ Antibacterial performance: The antibacterial rates of Examples 1-3 all exceeded 96%, showing good antibacterial effects. However, after using natural zeolite in Comparative Example 1, the antibacterial rate dropped to 75%, indicating that natural zeolite does not have the antibacterial function of clinoptilolite composite fillers. When ordinary fillers were used in Comparative Example 2, the antibacterial rate dropped significantly, indicating that the primer and topcoat prepared by the present invention play an important role in antibacterial performance.

[0083] ④ Photocatalytic performance: The photocatalytic degradation rates of Examples 1-3 are all above 80%, indicating that the photocatalytic effect of nano zinc oxide is effective. The photocatalytic degradation rate of Comparative Example 1 is reduced to 60% because natural zeolite does not have photocatalytic function. The photocatalytic performance of Comparative Example 2 is significantly weakened due to the use of ordinary fillers.

[0084] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An environmentally friendly antibacterial color steel plate, characterized in that: The invention comprises a steel plate and a bottom layer and a surface layer arranged on the steel plate. The primer used for the bottom layer comprises the following raw materials by mass percentage: 15-25% polyester resin, 8-16% clinoptilolite composite filler, 5-12% crosslinking agent, 40-50% solvent, 1-2% dispersant, 0.5-1% leveling agent and 1-2% anti-settling agent; the topcoat used for the surface layer comprises the following raw materials by mass percentage: 25-35% polyester resin, 10-15% pigment, 8-16% clinoptilolite composite filler, 8-18% crosslinking agent, 40-50% solvent, 1-2% dispersant, 0.5-1% leveling agent and 1-2% anti-settling agent.

2. The environmentally friendly antibacterial color steel plate according to claim 1, characterized in that: The solvents are all propylene glycol methyl ether acetate, and the polyester resins are all non-crystalline polyester resins.

3. The process for preparing an environmentally friendly antibacterial color steel plate according to claim 1, characterized in that: The following steps are included: Step 1: Fix the steel plate on the workbench of the sandblasting equipment, use corundum or glass beads with a particle size of 80-120 mesh as the abrasive, adjust the sandblasting pressure to 0.4-0.6MPa, and sandblast the surface of the steel plate for 1-3 minutes. Then immerse the sandblasted steel plate in a solution containing nano zinc oxide and iron oxide for 2-5 minutes to allow the nano materials to be evenly adsorbed on the surface of the steel plate; Step 2: Apply the primer evenly on the surface of the steel plate, controlling the coating thickness to 15-25 μm; place the coated steel plate in a microwave-assisted oven and bake it at 120-150°C for 20-40 seconds to quickly cure the primer and form a solid base layer; Step 3: Apply the topcoat evenly on the primer layer, controlling the coating thickness to 10-20 μm; place the coated steel plate in an oven at 160-180°C for 1-5 minutes; Step 4: Allow the cured color-coated steel plate to cool naturally to room temperature for inspection.

4. The process for preparing an environmentally friendly antibacterial color steel plate according to claim 3, characterized in that: The preparation method of the primer is specifically as follows: polyester resin and solvent are mixed and stirred uniformly to form a base resin solution; clinoptilolite composite filler is ball-milled to a particle size of 5-10 μm, and premixed with ethanol at 3000 rpm for 10 minutes to form a premix, a polymer dispersant is added to the premix, mixed and dispersed uniformly to form a suspension, and the suspension is slowly added to the base resin solution and mixed uniformly; an organosilicon leveling agent, an organobentonite anti-settling agent and an amino resin crosslinking agent are sequentially added and continuously stirred until completely uniform; and impurities and large particles are removed by filtering with a filter to prepare the primer.

5. The process for preparing an environmentally friendly antibacterial color steel plate according to claim 4, characterized in that: The preparation method of the topcoat specifically comprises the following steps: a. Mix the polyester resin and the solvent and stir to form a base resin solution; b. The pigment and polymer dispersant are mixed and stirred using a high-speed disperser for 10 minutes to form a pigment dispersion; c. The clinoptilolite composite filler was ball-milled to a particle size of 5-10 μm and premixed with ethanol at 3000 rpm for 10 minutes under high shear to form a premix; d. Mix the premix and pigment dispersion to form a suspension, slowly add it to the base resin solution and stir evenly; e. Add silicone leveling agent, organic bentonite anti-settling agent, and amino resin crosslinker in sequence, and continue stirring until completely uniform; f. Use a filter to remove impurities and large particles to obtain the topcoat.

6. The process for preparing an environmentally friendly antibacterial color steel plate according to any one of claims 4 or 5, characterized in that: The preparation method of the clinoptilolite composite filler is: (1) Preparation of zeolite gel: Sodium silicate and aluminum oxide were dissolved in sodium hydroxide solution, tetraethylammonium hydroxide was added, and the mixture was stirred to form a transparent gel. The mixture was aged at 80°C for 24 h, transferred to an autoclave, and crystallized at 160°C for 24 h. The mixture was filtered and washed with deionized water until neutral to obtain clinoptilolite gel. (2) Drying and sintering: The clinoptilolite gel was rinsed with anhydrous ethanol, dried at 120°C for 6 hours, placed in a muffle furnace, and calcined at 250°C for 4 hours to obtain a clinoptilolite composite filler.

7. The process for preparing an environmentally friendly antibacterial color steel plate according to claim 3, characterized in that: The primer and topcoat are both applied by electrostatic spraying.

Images