Long-acting corrosion-resistant environment-friendly coiled steel plate and preparation method of primer coating thereof

Abstract

The invention provides a long-acting corrosion-resistant environment-friendly coiled steel plate and a preparation method of a primer coating of the long-acting corrosion-resistant environment-friendly coiled steel plate and belongs to the technical field of coatings. Comprising a base plate, a primer coating and a finish coating, and the primer coating is prepared from, by mass, 40%-60% of epoxy modified polyester resin, 3%-5% of calcium ion exchange antirust pigment, 3%-5% of organic-inorganic composite antirust agent, 4%-6% of mixed ketone solvent, 3%-4% of aromatic hydrocarbon 100 # solvent, 6%-10% of dispersing agent, 3%-5% of titanium dioxide, 8%-12% of filler, 4%-7% of isocyanate and amino cross-linking agent and 0.2%-0.4% of defoaming agent. The coating is prepared from the following components in percentage by weight: 3-5% of epoxy phosphate, 0.2-0.4% of flatting agent, 3-5% of epoxy phosphate, 0.3-0.5% of phosphoric acid catalyst and the balance of diacetone alcohol. The calcium ion exchange anti-rust pigment and the organic-inorganic composite anti-rust agent are used for replacing a chromium-containing pigment, the GB 30981-2020 environmental protection standard is met, and toxic harm is avoided; through matching of the epoxy modified resin and the auxiliaries, the problems that a traditional coating is prone to cracking if hard and prone to damage if soft are solved, balance of hardness and toughness is achieved, and particularly the water erosion resistance of the bent position is improved.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a method for preparing a long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet and its primer coating. Background Technology

[0002] With the accelerating pace of social development, the demand for prefabricated buildings has also begun to grow rapidly. Color-coated pre-coated steel coils (PCM panels) have always been an important part of prefabricated buildings. From the beginning of the 20th century to the present, from industrial plants to convention centers and large airport projects, and then to light steel villas for civilian use, the application fields of PCM panels have become wider and wider, and the requirements for their lifespan and environmental protection have become higher and higher. Color-coated pre-coated steel coils (PCM panels) are typically processed into various complex tile shapes before use in prefabricated buildings to meet the needs of different locations and scenarios. Due to the varying levels of sophistication in domestic roll forming machines, some less automated machines are prone to damaging the softer coating when creating special shapes. Using a softer resin coating can cause wear, while using a harder resin coating can lead to cracking and peeling at the forming points after pressing. Furthermore, at bending points, the high temperature and humidity of summer essentially subject them to further damage, which most coatings cannot withstand. This invention achieves a perfect combination of hardness and toughness through special formulation design and selection of epoxy modified resin, organic-inorganic composite rust inhibitor and adhesion promoter. The adhesion between the coating and the substrate is also greatly enhanced, and the water resistance at the bending point is improved. In earlier years, in order to achieve ultra-long corrosion resistance, PCM boards usually used some pigments containing strontium chromate in the primer coating. However, due to its strong toxicity, long-term skin contact and inhalation of strontium chromate can cause organ damage. Therefore, GB 30981-2020 sets limits on the chromium content in coatings and requires all coating manufacturers to complete the implementation by January 1, 2022.

[0003] Currently, the industry uses polyphosphate or calcium ion exchange rust-preventive pigments, or a combination of both, as the rust-preventive pigments in environmentally friendly coil coating primers. However, while this approach performs well in normal dry environments, the paint film is prone to cracking and peeling at bends in high humidity and high temperature environments, thus losing its protective effect. Therefore, there is a need for a type of coil coating that can achieve long-term corrosion resistance in high temperature and high humidity environments. Summary of the Invention

[0004] This invention addresses the problems of existing technologies by providing a method for preparing long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheets and their coatings.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: A long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet includes a substrate, a primer coating, and a topcoat coating. The primer coating comprises the following raw materials by weight percentage: 40%-60% epoxy-modified polyester resin, 3%-5% calcium ion exchange rust-inhibiting pigment, 3%-5% organic-inorganic composite rust inhibitor, 4%-6% mixed ketone solvent, 3%-4% aromatic 100# solvent, 6%-10% dispersant, 3%-5% titanium dioxide, 8%-12% filler, 4%-7% isocyanate and amino crosslinking agent, 0.2%-0.4% defoamer, 0.2%-0.4% leveling agent, 3%-5% epoxy phosphate ester, 0.3%-0.5% phosphoric acid catalyst, and the balance being diacetone alcohol. Calcium ion exchange rust-inhibiting pigment and organic-inorganic composite rust inhibitor replace chromium-containing pigments, conforming to GB 30981-2020. Environmental standards are met to avoid toxic hazards; by combining epoxy modified resin with additives, the problem of traditional coatings being prone to cracking when hard or easily damaged when soft is solved, achieving a balance between hardness and toughness, especially improving the water erosion resistance at bends.

[0006] Preferably, the calcium ion exchange rust-preventive pigment includes one or more of G800 and strontium chrome yellow.

[0007] Preferably, the organic-inorganic composite rust inhibitor includes rust inhibitor CP9010.

[0008] Preferably, the topcoat is a highly corrosion-resistant polyester white-gray topcoat.

[0009] Preferably, the substrate is a zinc-plated substrate with an 80g zinc layer.

[0010] Preferably, the substrate has a surface roughness Ra≥0.8 and an RPC value≥80.

[0011] Preferably, the substrate needs to undergo surface pretreatment processes including alkaline washing and degreasing, circulating water rinsing, desalination water rinsing, and passivation.

[0012] Preferably, the filler includes one or more of barium sulfate, fumed silica, and polyethylene wax powder.

[0013] A method for preparing a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets is described below: Step 1: Pre-feeding: Add the mixed ketones, aromatic solvents, rust inhibitors, rust-inhibiting pigments, dispersants, resins, and fillers into the reactor with low-speed stirring in sequence to ensure uniform dispersion; Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy modified polyester resin, crosslinking agent, defoamer, leveling agent and catalyst in sequence, disperse evenly and adjust viscosity. After the performance is qualified, filter to obtain the primer coating.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention discloses a method for preparing a long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet and its primer coating. The method includes a substrate, a primer coating, and a topcoat coating. The primer coating raw materials are composed of the following components by mass percentage: 40%-60% epoxy-modified polyester resin, 3%-5% calcium ion exchange rust-inhibiting pigment, 3%-5% organic-inorganic composite rust inhibitor, 4%-6% mixed ketone solvent, 3%-4% aromatic 100# solvent, 6%-10% dispersant, 3%-5% titanium dioxide, 8%-12% filler, 4%-7% isocyanate and amino crosslinking agent, 0.2%-0.4% defoamer, 0.2%-0.4% leveling agent, 3%-5% epoxy phosphate ester, 0.3%-0.5% phosphoric acid catalyst, and the balance being diacetone alcohol. Calcium ion exchange rust-inhibiting pigment and organic-inorganic composite rust inhibitor replace chromium-containing pigments, conforming to GB standards. The 30981-2020 environmental standard avoids toxic hazards; by combining epoxy modified resin with additives, it solves the problem that traditional coatings are prone to cracking when hard and easily damaged when soft, achieving a balance between hardness and toughness, especially improving the water erosion resistance at bends. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a photograph of the PCM board with primer coating in Example 8, showing the results of the acid resistance test. Figure 2 This is a photograph of the alkali resistance test results of the PCM board with primer coating in Example 8. Figure 3 This is a photograph of the PCM board coated with primer in Example 8, showing the results of the neutral salt spray test. Figure 4 This is a photograph of the PCM board with primer coating in Example 8, showing the results of the scratch and salt spray resistance test. Figure 5 This is a photograph of the salt spray test results of the PCM board with primer coating in Example 8. Figure 6 This is a photograph of the QUV-A aging test results of the PCM board with primer coating in Example 8. Detailed Implementation

[0017] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0018] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0019] This application discloses a long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet, comprising a substrate, a primer coating, and a topcoat coating. The primer coating raw materials are composed of the following components by mass percentage: 40%-60% epoxy-modified polyester resin, 3%-5% calcium ion exchange rust-inhibiting pigment, 3%-5% organic-inorganic composite rust inhibitor, 4%-6% mixed ketone solvent, 3%-4% aromatic 100# solvent, 6%-10% dispersant, 3%-5% titanium dioxide, 8%-12% filler, 4%-7% isocyanate and amino crosslinking agent, 0.2%-0.4% defoamer, 0.2%-0.4% leveling agent, 3%-5% epoxy phosphate ester, 0.3%-0.5% phosphoric acid catalyst, and the balance being diacetone alcohol. The calcium ion exchange anti-rust pigment includes one or more of G800 and strontium chrome yellow; The organic-inorganic composite rust inhibitor includes rust inhibitor CP9010; The topcoat coating is a high corrosion-resistant polyester white-gray topcoat produced by Dongshun Coatings, with the specific model number as follows: The substrate is a zinc-plated substrate with an 80g zinc layer. The substrate needs to undergo surface pretreatment processes including alkaline washing and degreasing, circulating water rinsing, desalination water rinsing, and passivation. The surface roughness of the pretreated substrate is Ra≥0.8 and RPC value≥80. The filler includes one or more of barium sulfate, fumed silica, and polyethylene wax powder; A method for preparing a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets is described below: Step 1: Pre-feeding: Add the mixed ketones, aromatic solvents, rust inhibitors, rust-inhibiting pigments, dispersants, resins, and fillers into the reactor with low-speed stirring in sequence to ensure uniform dispersion; Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy modified polyester resin, crosslinking agent, defoamer, leveling agent and catalyst in sequence, disperse evenly and adjust viscosity. After the performance is qualified, filter to obtain the primer coating.

[0020] Example 1 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the low-speed stirring reactor: mixed ketone DCC 3%, aromatic hydrocarbon 100# 3%, rust inhibitor CP9010 0%, rust-inhibiting pigment G800 4%, anti-settling agent MH200FS 0.2%, dispersant DSF78S 0.6%, resin 3754H 15%, barium sulfate T10 9%, titanium dioxide CR510 5%, and polyethylene wax 1588SF 0.05% to ensure uniform dispersion. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the primer coating of Example 1; Example 2 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the low-speed stirring reactor: mixed ketone DCC 3%, aromatic hydrocarbon 100# 3%, rust inhibitor CP9010 0%, rust-inhibiting pigment G800 4%, anti-settling agent MH200FS 0.2%, dispersant DSF78S 0.6%, resin 3754H 15%, barium sulfate T10 9%, titanium dioxide CR510 5%, and polyethylene wax 1588SF 0.05% to ensure uniform dispersion. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the primer coating of Example 2; Example 3 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the reactor with low-speed stirring to ensure uniform dispersion: Mixed ketone DCC 3%, Aromatic hydrocarbon 100# 3%, Rust inhibitor CP9010 3.5%, Rust-inhibiting pigment G800 6%, Anti-settling agent MH200FS 0.2%, Dispersant DSF78S 0.6%, Resin 3754H 15%, Barium sulfate T10 9%, Titanium dioxide CR510 5%, and Polyethylene wax 1588SF 0.05%. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the primer coating of Example 3; Example 4 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the reactor with low-speed stirring to ensure uniform dispersion: Mixed ketone DCC 3%, Aromatic hydrocarbon 100# 3%, Rust inhibitor CP9010 2%, Rust-inhibiting pigment G800 4%, Anti-settling agent MH200FS 0.2%, Dispersant DSF78S 0.6%, Resin 3754H 15%, Barium sulfate T10 9%, Titanium dioxide CR510 5%, and Polyethylene wax 1588SF 0.05%. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the primer coating of Example 3; Example 5 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the low-speed stirring reactor: mixed ketone DCC 3%, aromatic hydrocarbon 100# 3%, rust inhibitor CP9010 5%, rust-inhibiting pigment G800 4%, anti-settling agent MH200FS 0.2%, dispersant DSF78S 0.6%, resin 3754H 15%, barium sulfate T10 9%, titanium dioxide CR510 5%, and polyethylene wax 1588SF 0.05% to ensure uniform dispersion. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and after the performance is tested and qualified, filter to obtain the primer coating of Example 5; Example 6 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the reactor with low-speed stirring to ensure uniform dispersion: Mixed ketone DCC 3%, Aromatic hydrocarbon 100# 3%, Rust inhibitor CP9010 3.5%, Rust-inhibiting pigment G800 4%, Anti-settling agent MH200FS 0.2%, Dispersant DSF78S 0.6%, Resin 3754H 15%, Barium sulfate T10 4%, Titanium dioxide CR510 10%, and Polyethylene wax 1588SF 0.05%. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the primer coating of Example 6; Example 7 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the reactor with low-speed stirring to ensure uniform dispersion: Mixed ketone DCC 3%, Aromatic hydrocarbon 100# 3%, Rust inhibitor CP9010 3.5%, Rust-inhibiting pigment G800 4%, Anti-settling agent MH200FS 0.2%, Dispersant DSF78S 0.6%, Resin 3754H 15%, Barium sulfate T10 6%, Titanium dioxide CR510 8%, and Polyethylene wax 1588SF 0.05%. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the primer coating of Example 7; Example 8 describes a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets, the preparation method of which is as follows: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the reactor with low-speed stirring to ensure uniform dispersion: Mixed ketone DCC 3%, Aromatic hydrocarbon 100# 3%, Rust inhibitor CP9010 3.5%, Rust-inhibiting pigment G800 4%, Anti-settling agent MH200FS 0.2%, Dispersant DSF78S 0.6%, Resin 3754H 15%, Barium sulfate T10 9%, Titanium dioxide CR510 5%, and Polyethylene wax 1588SF 0.05%. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy-modified polyester resin 3754H 41%, isocyanate PUH75 2%, trimethylamine resin 5747 4%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the primer coating of Example 8; Comparative Example 1 is a chromium-containing primer, and its preparation method is the same as that of Examples 1-8, as detailed below: Step 1: Pre-feeding: According to the mass percentage, the raw materials are added in the following order to the low-speed stirring reactor: mixed ketone DCC 4.5%, ethylene glycol butyl ether 3%, dispersant DSF78S 0.3%, resin 3754H 15%, anti-rust pigment Strontium chrome yellow 801 4.5%, barium sulfate T10 10%, titanium dioxide CR510 4.5%, anti-settling agent MH200FS 0.2%, and polyethylene wax 1588SF 0.05% to ensure uniform dispersion. Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy modified polyester resin 3754H 42%, isocyanate PUH75 1.8%, trimethylamine resin 5747 3.6%, defoamer XP50 0.2%, leveling agent 1695 0.2%, epoxy phosphate ester 7049 3.5%, phosphoric acid catalyst AD220C 0.4%, and the remainder is diacetone alcohol; after uniform dispersion, adjust the viscosity, and filter after passing the performance test to obtain the chromium-containing primer coating of Comparative Example 1.

[0021] Among them, the raw materials of the above mixed ketone DCC are from Chang Le United Chemical, the raw materials of resin 3754H, ethylene glycol butyl ether, aromatic hydrocarbon 100#, and amino 5747 are from Jiangsu Sanmu Chemical, the raw materials of dispersant DSF78S and rust inhibitor CP9010 are from Shanghai Jindao, the raw material of strontium chrome yellow 801 is from Shuangle Pigment, the raw material of barium sulfate T10 is from Tengmin Industry, the raw material of titanium dioxide CR510 is from Shandong Yantai Chemical, the raw material of isocyanate PUH75 is from Shanghai Hengtai, and the raw material of epoxy phosphate 7049 is from Jiangsu Buweilun.

[0022] The primer-coated coiled PCM steel sheets from Examples 1-8 and Comparative Example 1 were cut into several 7.5*15cm pieces and tested according to the specified test items. The test methods for T-bend, MEK, reverse impact, cross-cut adhesion test, pencil hardness, salt spray, scratch-affected salt spray, aging, and acid / alkali tests followed the methods recommended in GB / T13448-2019, and the rating was based on GB / T1766-2008. The results are shown in Table 1 below. Table 1. Mechanical property test results of PCM boards with primer coating in Examples 1-8 and Comparative Example 1

[0023] As shown in Table 1 above, the environmentally friendly coiled steel sheet and its coating produced by the primer coating of Example 8 of this application have the best long-term corrosion resistance. Therefore, this solution is preferred in industrial production. Its performance is close to that of coiled steel sheets produced by chromium-containing primers and can replace chromium-containing coiled steel in the market.

[0024] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet, comprising a substrate, a primer coating, and a topcoat coating, characterized in that, The raw material composition of its primer coating is as follows by mass percentage: 40%-60% epoxy modified polyester resin, 3%-5% calcium ion exchange anti-rust pigment, 3%-5% organic-inorganic composite anti-rust agent, 4%-6% mixed ketone solvent, 3%-4% aromatic 100# solvent, 6%-10% dispersant, 3%-5% titanium dioxide, 8%-12% filler, 4%-7% isocyanate and amino crosslinking agent, 0.2%-0.4% defoamer, 0.2%-0.4% leveling agent, 3%-5% epoxy phosphate ester, 0.3%-0.5% phosphoric acid catalyst, and the balance is diacetone alcohol.

2. The long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet according to claim 1, characterized in that, The calcium ion exchange rust-preventive pigment includes one or more of G800 and strontium chrome yellow.

3. The long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet according to claim 1, characterized in that, The organic-inorganic composite rust inhibitor includes rust inhibitor CP9010.

4. The long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet according to claim 1, characterized in that, The topcoat coating is a highly corrosion-resistant polyester white-gray topcoat.

5. The long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet according to claim 1, characterized in that, The substrate is a zinc-plated substrate with an 80g zinc layer.

6. The long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet according to claim 5, characterized in that, The substrate has a surface roughness Ra≥0.8 and an RPC value≥80.

7. The long-lasting, corrosion-resistant, and environmentally friendly coiled steel sheet according to claim 1, characterized in that, The substrate needs to undergo surface pretreatment processes including alkaline washing and degreasing, circulating water rinsing, desalination water rinsing, and passivation.

8. The long-lasting corrosion-resistant and environmentally friendly coiled steel sheet according to claim 1, wherein the filler comprises one or more of barium sulfate, fumed silica, and polyethylene wax powder.

9. The method for preparing a long-lasting, corrosion-resistant, and environmentally friendly primer coating for coiled steel sheets according to claims 1-8, characterized in that, The specific preparation method is as follows: Step 1: Pre-feeding: Add the mixed ketones, aromatic solvents, rust inhibitors, rust-inhibiting pigments, dispersants, resins, and fillers into the reactor with low-speed stirring in sequence to ensure uniform dispersion; Step 2: Grinding: Grind the material fed into the reactor to a fineness of less than 5μm; Step 3: Post-addition: Add epoxy modified polyester resin, crosslinking agent, defoamer, leveling agent and catalyst in sequence, disperse evenly and adjust viscosity. After the performance is qualified, filter to obtain the primer coating.

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