Multi-layer coating process for nano-silver organic composite antibacterial color coated steel plate

Abstract

The invention is applied to the technical field of steel plate coating processing, and discloses a nano-silver organic composite antibacterial color coating steel plate multilayer coating process, which comprises the following steps: S1, substrate pretreatment: carrying out surface degreasing, phosphorization and chromate treatment on a steel plate substrate, and then carrying out preheating treatment on the steel plate substrate; s2, primer coating, wherein the surface of the pretreated base plate is coated with nano-silver organic composite antibacterial primer; s3, coating of an intermediate coating, wherein the surface of the primer layer is coated with the nano-silver organic composite antibacterial intermediate coating; and S4, finish paint coating is conducted, specifically, the surface of the middle coating is coated with nano-silver organic composite antibacterial finish paint, and then the coated steel plate is cooled. According to the multi-layer coating process of the nano-silver organic composite antibacterial color coated steel plate, cell walls and cell membranes of bacteria and biological macromolecular structures such as protein and nucleic acid in the bacteria can be destroyed through a unique antibacterial mechanism of nano-silver, so that breeding and reproduction of the bacteria, fungi and viruses are efficiently inhibited.

Description

Technical Field

[0001] The invention relates to the technical field of steel plate coating processing, in particular to a multi-layer coating process for a nano-silver organic composite antibacterial color coating steel plate. Background Art

[0002] In today's industrial field and people's daily life scenes, steel plates play an extremely important role. The construction industry relies on steel plates to build solid frames and structures, and the home appliance industry uses steel plates to build shells to ensure the durability of products. At the same time, as society's attention to health and hygiene continues to rise, the shortcoming of ordinary steel plates lacking antibacterial properties has become increasingly obvious. In places with dense populations and high hygiene requirements such as hospitals, food processing workshops, and public transportation, bacteria, viruses and other microorganisms are easy to breed and multiply on the surface of steel plates, and spread through contact, causing cross-infection, posing a potential threat to people's health. Although the antibacterial coating technology has attempted to solve the antibacterial problem of steel plates to a certain extent, it has many limitations. The antibacterial effect of some antibacterial coatings is not long-lasting. After a period of use, the antibacterial ability has dropped significantly; some are difficult to mass-produce and apply due to the complex preparation process, resulting in high costs; others have poor adhesion when combined with steel plates, and are prone to coating peeling, and cannot effectively play an antibacterial and protective role. Summary of the invention

[0003] The purpose of the present invention is to provide a multi-layer coating process for nano-silver organic composite antibacterial color coated steel plate to solve the problems of the antibacterial coating proposed in the above background technology that the antibacterial effect is not durable enough, the preparation process is complicated and the adhesion is poor.

[0004] To achieve the above object, the present invention provides the following technical solution: a multi-layer coating process of a nano-silver organic composite antibacterial color coated steel plate, comprising the following steps: S1. Substrate pretreatment: The steel plate substrate is subjected to surface degreasing, phosphating and chromating treatments, and then the steel plate substrate is subjected to preheating treatments.

[0005] S2. Primer coating: coating the surface of the pretreated substrate with a nano-silver organic composite antibacterial primer.

[0006] S3. Intermediate coating coating: coating the surface of the primer layer with a nano-silver organic composite antibacterial intermediate coating.

[0007] S4. Topcoat coating: Coat the surface of the intermediate coating with a nano-silver organic composite antibacterial topcoat, and then cool the coated steel plate.

[0008] Preferably, the concentration of the alkaline degreasing agent in the degreasing treatment is 30-50 g / L, the treatment temperature is controlled at 50-60°C, and the treatment time is 2-3 min. The alkaline degreasing agent is fully contacted with the surface of the steel plate by spraying or dipping to remove surface oil and impurities, and then rinsed with clean water to ensure that there is no degreasing agent residue on the surface of the steel plate.

[0009] The above technical solution can effectively remove oil and impurities on the surface of the steel plate, provide a clean surface foundation for subsequent phosphating and other treatments, ensure good adhesion between the coating and the steel plate, and the appropriate concentration, temperature and time control can not only achieve efficient degreasing but also avoid adverse effects on the steel plate material.

[0010] Preferably, the phosphating treatment is to place the degreased steel plate in a phosphating solution for phosphating, the total acidity of the phosphating solution is 20-30 points, the free acidity is 1.0-2.0 points, the phosphating temperature is maintained at 40-50°C, the phosphating time is 1-2min, and the phosphating solution is applied to the surface of the steel plate by spraying or dipping to form a phosphating film on the surface of the steel plate. The thickness of the phosphating film is 2-5μm. After phosphating, it is thoroughly rinsed with clean water to remove the phosphating solution remaining on the surface.

[0011] By adopting the above technical scheme, a uniform phosphating film with a certain thickness can be formed on the surface of the steel plate, thereby enhancing the corrosion resistance of the steel plate. At the same time, its porous structure helps to improve the adhesion between the coating and the steel plate. Appropriate phosphating parameters can ensure that the quality of the phosphating film is stable and meets the process requirements.

[0012] Preferably, the concentration of the chromate treatment solution in the chromate treatment is 5-10 g / L, the treatment temperature is 30-40° C., the treatment time is 30-60 seconds, and the treatment method is immersion or spraying to form a chromate conversion film on the surface of the steel plate. The weight of the chromate conversion film is 20-50 mg / m². After the treatment, it is washed with deionized water and dried to enhance the adhesion between the substrate and the coating.

[0013] By adopting the above technical solution, the surface properties of the steel plate are further improved by forming a chromate conversion film, and its bonding with the coating is enhanced. The lower concentration of treatment solution and specific treatment conditions can reduce the usage and residue of chromate while ensuring the effect, thereby reducing the risk of environmental pollution.

[0014] Preferably, the primer is composed of a resin base, a nano-silver antibacterial agent, an additive and a solvent, the content of the nano-silver antibacterial agent is 5%-15% of the total weight of the primer, the coating method is roller coating or spraying, the coating thickness is 5-10 μm, and then baked at 150-200° C. for 5-15 minutes to dry and solidify it.

[0015] By adopting the above technical scheme, the nano-silver antibacterial agent in the primer gives the steel plate bottom layer antibacterial properties. The appropriate proportion can ensure the antibacterial effect while maintaining good film-forming properties and adhesion of the primer. Roller coating or spraying is easy to operate and can make the primer evenly covered. Specific baking conditions can make the primer fully dry and solidify to form a stable bottom coating.

[0016] Preferably, the nanosilver antibacterial agent is nanosilver particles, nanosilver wires or nanosilver flakes, and its particle size range is 10-100nm, the resin base material is a mixture of one or more of polyester resin, epoxy resin, acrylic resin or polyurethane resin, the auxiliary agent includes one or more of dispersant, wetting agent, thickener and curing agent, and the solvent is an organic solvent or water, or a mixed solvent of the two.

[0017] By adopting the above technical scheme, nanosilver antibacterial agents in different forms can provide a variety of antibacterial action modes and effects. Nanosilver in a specific particle size range has higher activity and antibacterial efficacy. A variety of resin base materials can be formulated into primers with different performance characteristics according to needs. Additives can improve the construction performance and coating quality of the primer. The solvent system is flexible and can adapt to different processes and environmental protection requirements.

[0018] Preferably, the intermediate coating is composed of resin, nano silver antibacterial agent, pigment, filler and additives, the content of nano silver antibacterial agent is 3%-10% of the total weight of the intermediate coating, the total content of pigment and filler is 20%-40% of the total weight of the intermediate coating, and the coating is applied by roller coating or flow coating with a coating thickness of 10-20 μm, and then baked at 180-220° C. for 8-12 min for drying and curing.

[0019] By adopting the above technical solution, the nanosilver in the intermediate coating further enhances the overall antibacterial ability, the pigments and fillers can provide rich colors and hiding power, meet the decorative needs and improve the physical properties of the coating, roller coating or flow coating can form an intermediate layer of uniform thickness, and specific baking conditions ensure its drying and curing effect and coating stability.

[0020] Preferably, the preheating temperature of the preheating treatment is 80-120° C., and the preheating time is 2-5 min.

[0021] By adopting the above technical solution, preheating the steel plate substrate can remove surface moisture and humidity, so that the substrate is at a suitable temperature state, which is conducive to the coating and adhesion of the primer, reduces the defects in the coating drying process, and improves the bonding strength between the coating and the substrate.

[0022] Preferably, the pigment in the intermediate coating is an inorganic pigment or an organic pigment, and the filler is one or more of talc powder, calcium carbonate, mica powder or kaolin.

[0023] By adopting the above technical scheme, inorganic pigments or organic pigments can provide a variety of color options to meet the decorative requirements of different application scenarios; while fillers such as talcum powder and calcium carbonate can improve the physical properties of the coating such as hardness, wear resistance, and weather resistance. The combination of different fillers can be formulated into an intermediate coating with excellent comprehensive performance according to actual needs.

[0024] Preferably, the topcoat is composed of resin, nano silver antibacterial agent, leveling agent, defoaming agent and solvent, the content of nano silver antibacterial agent is 2%-8% of the total weight of the topcoat, and the coating thickness is 15-25 μm by spraying or roller coating. Finally, it is baked at 200-250° C. for 10-15 min to complete drying and curing to form a nano silver organic composite antibacterial color coated steel plate. The cooling method of the cooling treatment is air cooling or water cooling, and the cooling is cooled to room temperature.

[0025] By adopting the above technical scheme, the nano-silver antibacterial agent in the topcoat ensures the antibacterial property of the steel plate surface, the leveling agent and the defoaming agent can improve the appearance quality of the topcoat, making its surface smooth, flat and free of defects; the appropriate coating thickness and baking conditions ensure the curing effect and protective performance of the topcoat, and air cooling or water cooling can quickly cool the steel plate to room temperature, thereby improving production efficiency and stabilizing coating performance.

[0026] Compared with the prior art, the invention has the following beneficial effects: the multi-layer coating process of the nano-silver organic composite antibacterial color coating steel plate: 1. Nanosilver has a unique antibacterial mechanism that can destroy bacterial cell walls, cell membranes, and internal biomacromolecule structures such as proteins and nucleic acids, thereby effectively inhibiting the growth and reproduction of bacteria, fungi and viruses. In the multi-layer coating process, nanosilver is evenly dispersed in the primer, intermediate coating and topcoat, forming a comprehensive antibacterial protection system, significantly reducing the attachment and survival of microorganisms, and effectively reducing the risk of cross infection; 2. By degreasing, phosphating and chromating the steel plate substrate, the oil and impurities on the steel plate surface can be effectively removed, and a dense phosphating film and chromate conversion film can be formed, which greatly improves the adhesion between the substrate and the coating, and at the same time enhances the anti-corrosion performance of the steel plate. The multi-layered organic composite coating further isolates the steel plate from the outside air, moisture and corrosive chemicals, forming a solid protective barrier. Compared with ordinary steel plates, the nano-silver antibacterial color coated steel plate has a longer service life in harsh natural or industrial environments, such as coastal areas with high humidity and high salinity; 3. The parameters of each step of the multi-layer coating process are clear, such as the concentration, temperature and time of the alkaline degreasing agent in the degreasing treatment, the relevant parameters of the phosphating treatment and the chromating treatment, and the coating thickness, baking temperature and time of each coating are all accurately set, which makes the entire coating process highly stable and repeatable, easy to operate and control in large-scale industrial production. Whether it is an automated production line or manual operation, it can stably produce nano-silver organic composite antibacterial color coated steel plate products with consistent quality according to the standard process flow, which is conducive to improving production efficiency, reducing production costs, and promoting the wide application and popularization of this technology in related industries; 4. The concentration of chromate treatment solution in this coating process is relatively low, and after treatment, it is washed with deionized water and dried, which reduces the emission and pollution of heavy metal chromium. At the same time, the long-term antibacterial and anti-corrosion properties of the nano-silver organic composite coating help to extend the service life of steel plate products and reduce the waste of resources and waste generation caused by premature damage of materials. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention provides a technical solution: a multi-layer coating process for a nano-silver organic composite antibacterial color coated steel plate.

[0029] The following are two examples of multi-layer coating process of nano-silver organic composite antibacterial color coated steel plates and the corresponding test data: Embodiment 1: 1. Substrate pretreatment: A 1.5m×3m×0.8mm steel plate substrate was selected, the concentration of the alkaline degreasing agent was adjusted to 35g / L, the treatment temperature was 52℃, degreasing was carried out by spraying for 2.2min, and then rinsed with clean water; The total acidity of the phosphating solution is 22 points, the free acidity is 1.2 points, the phosphating temperature is 42°C, the immersion phosphating is 1.3 minutes, and the phosphating film thickness on the steel plate surface after washing with water is about 2.5μm; The concentration of chromate treatment solution is 6g / L, immersion treatment is carried out at 32℃ for 40 seconds, deionized water cleaning and drying, the chromate conversion film weight is about 25mg / m², preheating to 90℃ for 2.2min; 2. Primer coating: The primer contains 55% epoxy resin, 8% nano silver particles (particle size 30nm), 6% dispersant, 4% thickener, and 27% organic solvent. The primer is roller-coated with a thickness of 6μm and cured by baking at 160℃ for 8min. 3. Intermediate coating application: The intermediate coating consists of 35% polyester resin, 4% nano silver wire (particle size 60nm), 30% talcum powder and mica powder mixture (1:1), 15% inorganic pigment, 3% curing agent, and 13% mixed solvent (water and organic solvent 3:7). The coating thickness is 12μm, and it is dried and cured by baking at 190℃ for 9min. 4. Topcoat coating and cooling: The topcoat contains 65% polyurethane resin, 3% nano silver flakes (particle size 20nm), 4% leveling agent, 3% defoamer, and 25% organic solvent. The topcoat is sprayed with a thickness of 18μm, baked at 210℃ for 11min, and air-cooled to room temperature. Test data: Antibacterial performance: The antibacterial rate against Escherichia coli is 99.2%, and the antibacterial rate against Staphylococcus aureus is 99.5%; Adhesion test: using the cross-hatch method, the adhesion level is 0 (no coating falling off); Salt spray resistance: After 800 hours of salt spray test, the coating surface has no rust and slight discoloration; Coating hardness: Pencil hardness test result is 3H.

[0030] Embodiment 2: 1. Substrate pretreatment: Take a 2m×4m×1mm steel plate, spray degrease with an alkaline degreasing agent concentration of 45g / L at 58℃ for 2.8min, and rinse with clean water; The total acidity of the phosphating solution is 28 points, the free acidity is 1.8 points, the phosphating is carried out at 48℃ for 1.8 minutes, the phosphating film thickness is about 4μm, and it is washed with clean water; The concentration of chromate treatment solution is 9g / L, immersed at 38℃ for 55 seconds, washed with deionized water and dried, the chromate conversion film weighs about 45mg / m², and preheated at 110℃ for 4.5min; 2. Primer coating: The primer is 65% acrylic resin, 12% nano silver particles (particle size 70nm), 4% wetting agent, 3% curing agent, 16% organic solvent, roller coating thickness 9μm, and cured by baking at 190℃ for 13min; 3. Intermediate coating application: The middle coating is composed of 45% epoxy resin, 6% nano silver wire (particle size 90nm), 22% calcium carbonate, 13% organic pigment, 4% dispersant, and 10% mixed solvent (water and organic solvent 2:8), with a roller coating thickness of 18μm and cured by baking at 210℃ for 11min; 4. Topcoat coating and cooling: The topcoat contains 75% polyester resin, 5% nano silver flakes (particle size 40nm), 3% leveling agent, 2% defoamer, and 15% organic solvent. The spraying thickness is 22μm, baked at 240℃ for 14min, and cooled to room temperature with water. Test data: Antibacterial properties: The antibacterial rate against Escherichia coli is 99.6%, and the antibacterial rate against Staphylococcus aureus is 99.8%.

[0031] Adhesion test: The adhesion level of the cross-cut test is 0 (no coating falling off).

[0032] Salt spray resistance: After 1200 hours of salt spray test, the coating has no rust and the degree of discoloration is minimal.

[0033] Coating hardness: pencil hardness reaches 4H.

[0034] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. A multi-layer coating process for nano-silver organic composite antibacterial color coating steel plate, characterized in that: The coating process includes the following steps: S1. Substrate pretreatment: Degreasing, phosphating and chromating the steel plate substrate, and then preheating the steel plate substrate; S2, primer coating: coating the surface of the pretreated substrate with a nano-silver organic composite antibacterial primer; S3, intermediate coating coating: coating the surface of the primer layer with a nano-silver organic composite antibacterial intermediate coating; S4. Topcoat coating: Coat the surface of the intermediate coating with a nano-silver organic composite antibacterial topcoat, and then cool the coated steel plate.

2. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1 is characterized by: The concentration of the alkaline degreasing agent in the degreasing treatment is 30-50g / L, the treatment temperature is controlled at 50-60°C, and the treatment time is 2-3min. The alkaline degreasing agent is fully contacted with the surface of the steel plate by spraying or dipping to remove surface oil and impurities, and then rinsed with clean water to ensure that there is no degreasing agent residue on the surface of the steel plate.

3. The multi-layer coating process of nano-silver organic composite antibacterial color coated steel plate according to claim 1 is characterized by: The phosphating treatment is to place the degreased steel plate in a phosphating solution for phosphating. The total acidity of the phosphating solution is 20-30 points, the free acidity is 1.0-2.0 points, the phosphating temperature is maintained at 40-50°C, the phosphating time is 1-2 minutes, and the phosphating solution is applied to the surface of the steel plate by spraying or dipping to form a phosphating film on the surface of the steel plate. The thickness of the phosphating film is 2-5μm. After phosphating, it is thoroughly rinsed with clean water to remove the phosphating solution remaining on the surface.

4. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1 is characterized by: The concentration of the chromate treatment solution in the chromate treatment is 5-10g / L, the treatment temperature is 30-40°C, the treatment time is 30-60 seconds, and the treatment method is immersion or spraying to form a chromate conversion film on the surface of the steel plate. The weight of the chromate conversion film is 20-50mg / m². After the treatment, it is washed with deionized water and dried to enhance the adhesion between the substrate and the coating.

5. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1 is characterized by: The primer is composed of a resin base material, a nano silver antibacterial agent, an auxiliary agent and a solvent. The content of the nano silver antibacterial agent is 5%-15% of the total weight of the primer. The primer is coated by roller coating or spraying with a coating thickness of 5-10 μm, and then baked at 150-200° C. for 5-15 minutes to dry and solidify.

6. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1 is characterized by: The nano silver antibacterial agent is nano silver particles, nano silver wires or nano silver sheets, and its particle size range is 10-100nm. The resin base material is a mixture of one or more of polyester resin, epoxy resin, acrylic resin or polyurethane resin. The auxiliary agent includes one or more of dispersant, wetting agent, thickener and curing agent. The solvent is an organic solvent or water, or a mixed solvent of the two.

7. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1 is characterized by: The intermediate coating is composed of resin, nano silver antibacterial agent, pigment, filler and additives, wherein the content of the nano silver antibacterial agent is 3%-10% of the total weight of the intermediate coating, and the total content of the pigment and filler is 20%-40% of the total weight of the intermediate coating. The intermediate coating is coated by roller coating or flow coating, with a coating thickness of 10-20 μm, and then baked at 180-220° C. for 8-12 minutes for drying and curing.

8. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1 is characterized by: The preheating temperature of the preheating treatment is 80-120° C., and the preheating time is 2-5 minutes.

9. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1, characterized in that: The pigment in the intermediate coating is an inorganic pigment or an organic pigment, and the filler is one or more of talc powder, calcium carbonate, mica powder or kaolin.

10. The multi-layer coating process of nano-silver organic composite antibacterial color coating steel plate according to claim 1, characterized in that: The topcoat is composed of resin, nano silver antibacterial agent, leveling agent, defoaming agent and solvent, wherein the content of the nano silver antibacterial agent is 2%-8% of the total weight of the topcoat, and the coating thickness is 15-25 μm by spraying or roller coating. Finally, the topcoat is baked at 200-250° C. for 10-15 minutes to complete drying and curing, so as to form a nano silver organic composite antibacterial color coated steel plate. The cooling method of the cooling treatment is air cooling or water cooling, and the topcoat is cooled to room temperature.