Environment-friendly corrosion-resistant polyurethane color steel plate and processing method thereof

Abstract

This invention discloses an environmentally friendly and corrosion-resistant polyurethane color steel plate, comprising an upper composite corrosion-resistant surface layer, an upper interlocking adhesive reinforcement layer, and a first reinforcing layer. A processing method for the environmentally friendly and corrosion-resistant polyurethane color steel plate includes: S1: preparing the upper and lower composite corrosion-resistant surface layers; S2: preparing the upper and lower interlocking adhesive reinforcement layers; S3: preparing the first and second reinforcing layers; S4: preparing a modified polyurethane core layer; S5: bonding each structural layer layer by layer; S6: fixing a flake-like sheet layer on the outer surface of the color steel plate; S7: performing all-around corrosion-resistant sealing; and S8: finished product inspection and cutting. By setting a composite corrosion-resistant surface layer and a flake-like protective layer, combined with an all-around sealing structure, this application significantly improves the corrosion resistance of the color steel plate, enabling it to withstand long-term salt spray erosion and acid / alkali immersion, effectively blocking the penetration of corrosive media, preventing coating peeling and substrate corrosion, and significantly extending its service life.

Description

Technical Field

[0001] This invention relates to the field of polyurethane color steel processing technology, and in particular to an environmentally friendly and corrosion-resistant polyurethane color steel sheet and its processing method. Background Technology

[0002] Polyurethane color steel panels are integrated building cladding materials that feature sandwich insulation, lightweight high strength, fire resistance, and sound insulation.

[0003] Polyurethane color steel panels are widely used in building envelopes, industrial plants, and other applications due to their advantages of being lightweight, heat-insulating, and easy to install. However, traditional products have significant drawbacks: the surface layer lacks sufficient corrosion resistance and scratch resistance, making it prone to coating peeling and substrate corrosion in harsh environments; the adhesive layer has limited strength and lacks anti-corrosion properties, leading to delamination after long-term use; the core layer lacks sufficient modification, resulting in poor flame retardancy and reinforcement, and the overall sealing is incomplete, allowing corrosive media to easily seep in through gaps, thus shortening its service life. Therefore, this application proposes an environmentally friendly and corrosion-resistant polyurethane color steel panel and its processing method. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an environmentally friendly and corrosion-resistant polyurethane color steel plate and its processing method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An environmentally friendly and corrosion-resistant polyurethane color steel plate includes an upper composite corrosion-resistant surface layer, an upper interlocking adhesive reinforcement layer, a first reinforcement layer, a modified polyurethane core layer, a second reinforcement layer, a lower interlocking adhesive reinforcement layer, and a lower composite corrosion-resistant surface layer. The modified polyurethane core layer has a sloping sealing groove at its edge, and a fluororubber sealing strip is embedded in the sealing groove and filled with sealant.

[0007] The color steel plate has aluminum alloy corner protectors at its edges and corners, and rivets are riveted to the aluminum alloy corner protectors. The gaps between the structural layers at the edges and corners of the color steel plate are filled with environmentally friendly and corrosion-resistant sealant. The upper composite corrosion-resistant surface layer and the lower composite corrosion-resistant surface layer are symmetrical in structure. Both the upper composite corrosion-resistant surface layer and the lower composite corrosion-resistant surface layer include a substrate, an epoxy transition layer, a fluorocarbon anti-corrosion layer and trapezoidal reinforcing ribs. The surface of the substrate is provided with honeycomb-shaped micro-concavities.

[0008] Preferably, both the upper interlocking adhesive reinforcement layer and the lower interlocking adhesive reinforcement layer include a modified adhesive, micro-bumps, and rectangular interlocking grooves. The micro-bumps are precisely fitted with the honeycomb-shaped micro-concave of the substrate. The rectangular interlocking grooves are nested with the rectangular bosses of the reinforcement layer. The nesting gap between the rectangular interlocking grooves and the rectangular bosses of the reinforcement layer is less than or equal to 0.05 mm. The modified adhesive is prepared by mixing bisphenol A type epoxy resin and polyamide 650 curing agent in a 4:1 mass ratio. The modified adhesive contains 0.8-1.0 wt% silane coupling agent and 0.3-0.5 wt% titanium dioxide corrosion-resistant filler.

[0009] Preferably, the first reinforcing layer and the second reinforcing layer have the same structure. The first reinforcing layer and the second reinforcing layer include a glass fiber reinforced epoxy resin substrate, a rectangular boss, a diamond-shaped reinforcing texture, and an epoxy anti-corrosion coating. The substrate is formed by hot pressing alkali-free glass fiber cloth impregnated with epoxy resin. The epoxy anti-corrosion coating is an epoxy zinc-rich primer with a zinc content of ≥80%.

[0010] Preferably, the modified polyurethane core layer is made by mixing isocyanate and polyol in a mass ratio of 1.1:1, and the modified polyurethane core layer is supplemented with composite flame retardant, organosilane coupling agent and basalt reinforcing fiber.

[0011] A processing method for environmentally friendly and corrosion-resistant polyurethane color steel sheet includes:

[0012] S1: The upper and lower composite corrosion-resistant surface layers are prepared by sequentially processing the substrate, coating, and reinforcing ribs. The substrate is an AZ150 grade zinc-aluminum-magnesium substrate with a thickness of 0.5-0.7mm. It is subjected to environmentally friendly alkaline degreasing, dilute hydrochloric acid pickling, sodium carbonate solution neutralization, segmented hot air drying, and fiber laser micro-engraving. After drying, the moisture content of the substrate does not exceed 0.1%. The laser micro-engraving process creates hexagonal honeycomb-shaped micro-concaves.

[0013] After micro-engraving, the coating is cleaned with high-pressure air and inspected under a magnifying glass to ensure it passes inspection. The coating is prepared using a high-pressure electrostatic spraying machine, which sequentially applies an epoxy transition layer and a fluorocarbon anti-corrosion layer. After being cured at a constant temperature, the coating adhesion is tested through a cross-cut test to ensure no peeling. The reinforcing ribs are formed using multiple sets of cold bending and rolling machines to process trapezoidal reinforcing ribs. After rolling, they are leveled by a leveling machine. Positioning fixtures are used to ensure that the reinforcing ribs of the upper and lower composite corrosion-resistant surfaces are accurately aligned, with a misalignment error of no more than 0.1 mm. After passing inspection, they are paired and ready for use.

[0014] S2: The upper interlocking adhesive reinforcement layer and the lower interlocking adhesive reinforcement layer are prepared by sequentially performing adhesive preparation, layer molding, and interlocking groove processing. The adhesive preparation involves mixing bisphenol A epoxy resin, polyamide curing agent, acetone diluent, KH-550 silane coupling agent, and nano-titanium dioxide corrosion-resistant filler in a certain proportion, and then mixing at high speed, cooling in a water bath, and allowing to stand for defoaming before use.

[0015] The layer forming process uses a stainless steel scraper coating machine to apply the modified adhesive to the non-reinforcing surfaces of the upper and lower composite corrosion-resistant layers. Simultaneously, micro-protrusions that precisely match the honeycomb-shaped micro-concavities are formed. After coating, a constant temperature pre-drying treatment is performed to ensure that the adhesive is initially formed and free from adhesion. After the adhesive has cured to 60%-70%, a rectangular interlocking groove is processed using a carbon dioxide laser engraving process. After engraving, the groove is cleaned with high-pressure air and its dimensional accuracy is checked with calipers. Once qualified, it forms an integrated structure with the composite corrosion-resistant layer for later use.

[0016] S3: The first and second reinforcing layers are prepared by sequentially performing substrate molding, protrusion and reinforcing texture processing, and anti-corrosion coating process; the substrate molding uses alkali-free glass fiber cloth, which is impregnated with epoxy resin and then vacuum hot-pressed and cooled for testing to ensure that the layer strength meets the standards.

[0017] The bosses and reinforcing grooves are processed using fiber laser cutting technology to ensure precise matching between the rectangular bosses and the rectangular interlocking grooves, with no overcutting or missing cuts, and the diamond-shaped reinforcing grooves are neat and burr-free; the anti-corrosion coating is applied using a high-precision roller coating machine, with epoxy zinc-rich primer applied to the upper and lower surfaces of the reinforcing layer. After constant temperature curing, the adhesion is tested by cross-cut test and the corrosion resistance is tested by neutral salt spray test. Once qualified, it is ready for use.

[0018] S4: Prepare the modified polyurethane core layer by sequentially going through the processes of raw material preparation, foaming and molding, and sealing groove processing. The raw material preparation involves mixing isocyanate MDI-50, polyol POP-3628 and various modifiers in proportion, stirring at high speed, cooling in a water bath, and then filtering through a 300-mesh stainless steel filter for later use.

[0019] The foaming process uses a high-pressure foaming machine to inject the raw material into a preheated custom steel mold, controlling the foaming ratio to 30-40 times. After foaming, the material is cured at a constant temperature and demolded to ensure that the core layer surface is free of defects. The sealing groove is processed using CNC milling technology, which processes a 45° inclined sealing groove at the edge of the core layer. After milling, the burrs are removed by wet sanding with sandpaper. The closed-cell rate, thermal conductivity and sealing groove size of the core layer are tested. Once qualified, the material is ready for use.

[0020] S5: Each structural layer is composited layer by layer, and double fixation is achieved through hot pressing interlocking process and hot melt bonding process; first, the lower composite corrosion-resistant surface layer and the second reinforcing layer are fixed by hot pressing interlocking process after CCD visual positioning. The hot pressing pressure is 0.8-1.0MPa, the temperature is 60-70℃, and the time is 15-20min. The segmented pressurization method is used to ensure tight interlocking.

[0021] Then, the modified polyurethane core layer is fixed to the lower composite layer and the first reinforcing layer by hot melt bonding process. The bonding temperature is 80-90℃ and the pressure is 0.5-0.6MPa to ensure that the reinforcing layer is symmetrical and there is no core layer deformation. Finally, the upper composite corrosion-resistant surface layer and the first reinforcing layer are fixed by repeating the above hot pressing bonding process to ensure that there is no delamination, gaps and delamination of each structural layer.

[0022] S6: Fix the scale-like sheet layer on the outer surface of the color steel plate. The process steps and parameters are completely consistent with S4 in this embodiment 2. After the sheet is fixed, the edge is treated and the curing test is performed, it is ensured that the sheet is not loose or falling off.

[0023] S7: Perform all-round corrosion-resistant sealing. The process steps and parameters are completely consistent with S5 in this embodiment 3. The process includes side sealing, corner sealing, interface sealing, and overall curing to ensure that there are no omissions or bubbles in the seal and that the degree of curing meets the standard.

[0024] S8: Finished product inspection and cutting. After passing the inspection, the cut edges are sealed. For finished product inspection, 10 products are randomly selected from each batch. The inspection items include corrosion resistance, structural strength, sealing performance, heat insulation performance, dimensional accuracy, and appearance quality. Unqualified products are reworked. Cutting is carried out using CNC cutting equipment according to actual needs. After the cut edges are wet sanded with sandpaper, they are coated with environmentally friendly corrosion-resistant sealant and sealed. After static curing, they are inspected again. After passing the inspection, the product number, specifications, and production date are marked and stored for future use.

[0025] Preferably, the substrate processing in step S1 includes degreasing, pickling, neutralization, drying and laser micro-engraving. The laser micro-engraving process forms a regular hexagonal honeycomb-shaped micro-concave, and the concave diameter is 0.8-1.2 mm and the depth is 0.3-0.5 mm.

[0026] Preferably, in step S7, the side sealing adopts a combination of fluororubber sealing strip and secondary glue injection. The fluororubber sealing strip has a temperature resistance range of -40℃ to 150℃ and a corrosion resistance grade of C4. The corners of the fluororubber sealing strip are wrapped with 6061 aluminum alloy corner protectors, which are fixed by applying glue and riveting. The riveting pressure is 1.0-1.2MPa and the riveting spacing is 50-80mm. The whole thing is cured by standing for 12-24 hours at a temperature of 25±2℃ and a humidity of 40%-50%, with a degree of curing ≥98%.

[0027] Preferably, in step S6, the scaly sheet layer is made of 316L stainless steel micro-sheets or alumina ceramic micro-sheets with a thickness of 0.1-0.2mm. After laser cutting, grinding, cleaning and drying, the edge radius of the sheet is 0.1-0.2mm. It is double-fixed by epoxy dispensing and edge embedding, and the curing degree of the sealant is ≥98%.

[0028] The present invention has the following beneficial effects:

[0029] 1. By setting a composite corrosion-resistant surface layer and a flake-like protective layer, combined with an all-round sealing structure, the corrosion resistance of the color steel plate of this application is greatly improved. It can withstand long-term salt spray erosion and acid and alkali media immersion, effectively blocking the penetration of corrosive media, avoiding coating peeling and substrate corrosion, and significantly extending service life.

[0030] 2. By setting an interlocking adhesive reinforcement layer and a double reinforcement layer, and adopting a double fixing method of nested boss interlocking grooves and heating and melting bonding, the structural layers of this application are firmly bonded, with excellent bending and impact resistance, which completely solves the problem of easy delamination and loosening of traditional products, while ensuring the stable thermal insulation performance of the core layer.

[0031] 3. By using formaldehyde-free epoxy modified adhesives, environmentally friendly degreasing agents, and other green raw materials, combined with precise production processes, this application ensures that no harmful gases are released during the production process, meeting green and environmental protection requirements. At the same time, the product has high dimensional accuracy, a smooth and defect-free appearance, and is suitable for various construction and installation needs, taking into account both environmental protection and practicality. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of an environmentally friendly and corrosion-resistant polyurethane color steel plate proposed in this invention;

[0033] Figure 2 This is a partial structural diagram of the upper composite corrosion-resistant layer of an environmentally friendly and corrosion-resistant polyurethane color steel plate proposed in this invention.

[0034] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0035] Figure 4 This is a schematic diagram of the diamond-shaped reinforcing pattern of an environmentally friendly and corrosion-resistant polyurethane color steel plate proposed in this invention; Figure 5 for Figure 4 Enlarged view at point B in the middle;

[0036] Figure 6 This is a schematic diagram of the polyurethane core layer of an environmentally friendly and corrosion-resistant polyurethane color steel plate proposed in this invention.

[0037] Figure 7 This is a schematic diagram illustrating the processing technology of an environmentally friendly and corrosion-resistant polyurethane color steel plate proposed in this invention.

[0038] In the diagram: 1 Aluminum alloy corner protector, 2 Rivet, 3 Scale-like sheet layer, 4 Modified polyurethane core layer, 5 Upper composite corrosion-resistant surface layer, 6 Fluororubber sealing strip, 7 Epoxy transition layer, 8 Fluorocarbon anti-corrosion layer, 9 Trapezoidal reinforcing rib, 10 Substrate, 11 Honeycomb micro-concave, 12 Micro-protrusion, 13 Upper interlocking adhesive reinforcement layer, 14 Rectangular interlocking groove, 15 Rectangular boss, 16 Diamond-shaped reinforcing pattern, 17 Sloping sealing groove, 18 First reinforcing layer, 19 Second reinforcing layer. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0040] Example 1:

[0041] S1: Preparation of the Basic Anti-corrosion Surface Layer. The substrate is made of 0.6mm thick AZ150 galvanized aluminum-magnesium sheet, which undergoes environmentally friendly alkaline degreasing, dilute hydrochloric acid pickling, sodium carbonate neutralization, segmented hot air drying (moisture content ≤0.1%), and laser micro-engraving. The laser micro-engraving forms a regular hexagonal honeycomb micro-concave structure, which improves the adhesion of subsequent coatings. After substrate treatment, an epoxy transition layer and a PVDF fluorocarbon anti-corrosion layer are applied sequentially using a high-voltage electrostatic spraying process. The epoxy transition layer is 20μm thick and cured at 85℃ for 35min, with an adhesion grade ≥1; the PVDF fluorocarbon anti-corrosion layer is 28μm thick and cured at 210℃ for 75min, with an adhesion grade 0, forming the basic anti-corrosion surface layer.

[0042] S2: Ordinary polyurethane core foam. The polyurethane core layer is made by mixing isocyanate and polyol in a mass ratio of 1.1:1, with a foaming ratio controlled at 35 times. It is then injection molded at a preheated temperature of 45-55℃ and demolded after the core layer has cured to ≥95%.

[0043] S3: The layered composite layer adopts a segmented hot-pressing process with a hot-pressing temperature of 65℃, a pressure of 0.9MPa, and a total hot-pressing time of 18min to ensure that the upper and lower anti-corrosion surface layers are tightly bonded to the polyurethane core layer with an adhesion strength of ≥1.0MPa and no delamination or peeling.

[0044] S4: Finished Product Inspection and Cutting. Finished product inspection focuses on verifying core performance indicators, requiring no rust after 500 hours of neutral salt spray test, bending strength ≥8MPa, thermal conductivity ≤0.025W / (m・K), and dimensional error controlled within ±0.2mm, to meet the basic anti-corrosion, thermal insulation, and structural use requirements of building envelope.

[0045] Example 2:

[0046] S1-S3: The process steps and parameters of the preparation of the anti-corrosion surface layer, the foaming of the ordinary polyurethane core layer, and the layer composite are completely consistent with those in Example 1, and the basic polyurethane color steel plate matrix is ​​obtained for later use.

[0047] S4: Fixation of the scaly layer 3

[0048] S4: Fixing of the Scale-like Sheet Layer 3: Scale-like zinc-aluminum alloy sheets are selected, with a sheet thickness of 0.1-0.2mm and a scale size of 5-8mm. The surface is modified with silane coupling agent KH-550. Using specialized adhesive application equipment, the epoxy-modified adhesive is evenly applied to the back of the sheet, with a coating thickness of 5-8μm (error ±0.5μm). Immediately after coating, the sheet is evenly laid on the surface of the composite structure, with an overlap width of 1-2mm and an overlap error ≤0.1mm. It is then lightly pressed and fixed using a pressure roller (pressure 0.2-0.3MPa). After laying, it is placed in a constant temperature curing oven and cured at 70-80℃ for 20-30 minutes. After curing, the adhesion of the sheet is tested to ensure there is no loosening or peeling, and the sheet is laid flat without curling edges. Once qualified, it proceeds to the next process.

[0049] S5: Finished Product Inspection and Cutting

[0050] Based on the testing items in Example 1, a new requirement for the flake layer is added: the flake layer must be free of looseness or peeling, the sealant must be free of cracks or bubbles, and the overlap width must meet the design requirements. The standards for the remaining testing items are the same as in Example 1. After passing the inspection, the product is CNC cut, the cut edges are ground without sealing, and then marked with the product number, specifications, and production date before being put into storage.

[0051] Example 3:

[0052] S1-S3: The process steps and parameters of the preparation of the anti-corrosion surface layer, the foaming of the ordinary polyurethane core layer, and the layer composite are completely consistent with those in Example 1, and the basic polyurethane color steel plate matrix is ​​obtained for later use.

[0053] S4: Construction of the fixation of the scaly layer 3: The process steps and parameters are completely consistent with those of S4 in Example 2.

[0054] S5: All-around corrosion-resistant sealing structure molding

[0055] All-around corrosion-resistant sealing molding: Environmentally friendly polysulfide sealant is selected, with a viscosity of 1800-2200 mPa·s at 25℃. A high-precision dispensing gun is used to evenly inject the sealant into the sealing groove 17 at the edge of the core layer and the joints between each layer. The thickness of the sealant is 3-5mm and the width is 5-8mm, ensuring that the sealant fills the gaps completely, without air bubbles or gaps. After dispensing, the surface of the sealant is smoothed with a scraper to make it flush with the surface of the structure. Then, it is allowed to cure at room temperature (25±2℃) for 4-6 hours. After the degree of curing is ≥90%, the sealing effect is inspected with a magnifying glass to ensure that there are no leaks or cracks, and that the sealing layer adheres tightly to each layer, forming an all-around corrosion-resistant sealing structure.

[0056] S6: Finished Product Inspection and Cutting

[0057] Based on the testing items in Example 2, the following sealing structure testing requirements are added: Water penetration test: no water seepage or leakage after 24 hours at 0.3 MPa; no media penetration into the interior after 72 hours of immersion in 5% hydrochloric acid solution; no cracking or peeling of the sealing layer; no loosening of the corner seals; other testing items are consistent with the standards in Example 1. After passing the tests, the product is CNC cut, the cut edges are ground, and then sealed with environmentally friendly corrosion-resistant sealant with a thickness of 1-2 mm and a width of 5 mm. It is left to stand for 2 hours to allow the sealant to initially cure. The cut edges are then tested again for leaks. The product number, specifications, and production date are marked before warehousing.

[0058] Example 4:

[0059] S1: Preparation of composite corrosion-resistant surface layer

[0060] S1-1: Substrate treatment: Select a high-strength zinc-aluminum-magnesium substrate 10 with a thickness of 0.5-0.7mm (error ±0.05mm) and grade AZ150, with a coating weight ≥150g / ㎡ and tensile strength ≥345MPa, and the surface is free of oxide layer, scratches and oil stains. The substrate 10 is degreased with an environmentally friendly alkaline degreasing agent (pH 10-11, concentration 80-100g / L) at 50-60℃ for 15-20 minutes, supplemented by ultrasonic vibration at 20kHz and 500W. Then, it is acid-washed with 5-8% dilute hydrochloric acid (volume ratio 1:12-1:18) at 25-30℃ for 3-5 minutes (stirring once every 1 minute), then neutralized with 3-5% sodium carbonate solution for 2-3 minutes, and then sent to a segmented heating and drying oven (front section 100-110℃, middle section 120-130℃, rear section 90-100℃) for 10-15 minutes to ensure that the surface moisture content is ≤0.1%.

[0061] After drying, honeycomb-shaped micro-concaves are micro-engraved using an 80-100W fiber laser at a speed of 300-500mm / min. The diameter of the concave pits is 0.8-1.2mm and the depth is 0.3-0.5mm (error ±0.03mm). The pits are distributed in regular hexagons with a spacing of 2-3mm. After cleaning with 0.3-0.5MPa high-pressure air, the products are then inspected, and any defective products are reprocessed.

[0062] S1-2: Coating Preparation: On the treated substrate 10 surface, a high-voltage electrostatic spraying process is applied to form an epoxy transition layer 7 (epoxy resin E-44: polyamide 650 = 4:1 mass ratio) at a spraying distance of 200-300mm and a speed of 150-200mm / min. The thickness is 18-22μm (error ±1μm). The layer is cured at 80-90℃ for 30-40min. After cooling to 25±2℃, the adhesion in a cross-cut test is ≥1. Subsequently, a PVDF fluorocarbon anti-corrosion layer 8 (solid content ≥70%) is applied using the same spraying method, with a thickness of 25-30μm (error ±1μm). After leveling at 60℃ and 5m / min, the layer is cured at 200-220℃ for 60-90min. After segmented cooling to room temperature, the adhesion in a cross-cut test reaches grade 0, and the gloss at 60° gloss is ≥80%. After passing the test, the process proceeds to the next step.

[0063] S1-3: Rib Forming: Using a Cr12MoV quenched mold (HRC60-62, accuracy ±0.03mm), trapezoidal reinforcing ribs 9 are cold-bent and rolled at a speed of 5-8m / min and a pressure of 0.6-0.8MPa. The rib spacing is 150-200mm (error ±1mm), the rib height is 8-10mm (error ±0.1mm), the bottom of the cross-section is 12-15mm, and the top is 8-10mm. After rolling, the ribs are leveled at 0.3-0.5MPa and 3-5m / min to ensure flatness ≤0.2mm / m. After passing the inspection, the upper composite corrosion-resistant surface layer 5 is obtained and marked for later use.

[0064] S1-4: Preparation of the lower composite corrosion-resistant surface layer: Prepared according to the same process as S1-1 to S1-3, using a ±0.05mm positioning fixture to align the reinforcing ribs, with a misalignment error ≤0.1mm. After passing the inspection, it is paired with the corresponding upper composite corrosion-resistant surface layer 5 for later use.

[0065] S2: Preparation of interlocking adhesive reinforcement layer

[0066] S2-1: Adhesive preparation: According to the mass ratio of epoxy resin E-51:polyamide 650=4:1, add 5-8% acetone diluent, 0.8-1.0wt% KH-550 silane coupling agent, and 0.3-0.5wt% 50-100nm titanium dioxide filler. Stir at 2000-2500r / min for 30-40min under water bath cooling at 25-30℃. Let stand for 5-10min to eliminate air bubbles. Control the viscosity at 25℃ to 2000-2500mPa·s. Seal and store for ≤2h.

[0067] S2-2: Layer Forming: Apply the modified adhesive to the non-reinforcing surfaces of the upper and lower composite corrosion-resistant layers using a scraper at a speed of 10-15 m / min and a pressure of 0.2-0.3 MPa, with a thickness of 10-12 μm (error ±0.5 μm). Simultaneously form micro-protrusions 12 that precisely match the honeycomb-shaped micro-concavities 11 (protrusion size is 0.1 mm smaller than the concavities). After coating, pre-dry at 50-60℃ for 10-15 min until the adhesive cures to 30-40% (no stickiness to the touch), then remove and set aside.

[0068] S2-3: Interlocking Groove Processing: After the adhesive has cured to 60%-70% (D40-D50), use a 60-80W CO2 laser to carve rectangular interlocking grooves 14 at a carving speed of 200-300mm / min. The groove dimensions should match the reinforcement layer bosses (gap ≤0.05mm). After carving, clean the grooves with 0.2MPa high-pressure air and check the dimensional accuracy with ±0.01mm calipers (error ≤±0.05mm) to ensure the groove walls are burr-free. Once qualified, the upper and lower interlocking adhesive reinforcement layers are obtained and marked for later use.

[0069] S3: Preparation of the reinforcement layer

[0070] S3-1: Substrate Molding: Select 10-15μm thick alkali-free glass fiber cloth (warp and weft density 20 threads / cm), impregnate with epoxy resin E-44 and polyamide 650 (3:1 mass ratio) (with 0.5% defoamer), impregnate at 25-30℃ for 5-8 minutes, then hot press at 120-130℃ and 1.0-1.2MPa for 15-20 minutes (vacuum degree -0.08MPa). After cooling, check the layer thickness to be 15-20μm (error ±0.5μm), tensile strength ≥300MPa, flexural strength ≥200MPa. If qualified, proceed to the next process.

[0071] S3-2: Machining of bosses and reinforcing patterns: Use a 70-90W fiber laser to cut rectangular bosses 15 that match the interlocking groove (error ±0.03mm), and then process rhomboid reinforcing patterns 16 with a power of 60-70W (side length 5-8mm, pattern depth 1-2μm, spacing 10-15mm). After the boss size and reinforcing pattern distribution are found to be qualified, they are ready for use.

[0072] S3-3: Anti-corrosion coating application: Apply epoxy zinc-rich primer (zinc content ≥80%) to both sides of the reinforcing layer using a roller at a speed of 8-12 m / min and a pressure of 0.1-0.2 MPa. The viscosity should be 1000-1500 mPa·s at 25℃. Curing should be carried out at a constant temperature of 70-80℃ for 20-30 min. After cooling, the adhesion should be ≥1 in the cross-cut test. After 24 hours of neutral salt spray testing (5% NaCl, 35℃), no peeling or rust should be observed. Once qualified, the first and second reinforcing layers 19 are obtained and marked for later use.

[0073] S4: Foaming and molding of modified polyurethane core layer 4

[0074] S4-1: Raw material preparation: Add 4-5wt% composite flame retardant (magnesium hydroxide: aluminum hydroxide = 2:1), 1.5-2.0wt% KH-560 coupling agent, and 0.5-1.0wt% basalt reinforcing fiber at a mass ratio of isocyanate MDI-50: polyol POP-3628 = 1.1:1. Stir at 1500-2000r / min for 20-30min under water bath cooling at 25-30℃. After filtration through a 300-mesh filter, control the viscosity at 25℃ to 800-1200mPa·s. Pour into a high-pressure foaming machine for later use (preparation time ≤ 1h).

[0075] S4-2: Foaming Molding: Coat a custom steel mold (roughness Ra≤0.8μm) with 0.05-0.1mm of silicone release agent, preheat at 45-55℃ for 10-15min, and inject foaming material at a pressure of 1.5-2.0MPa and a speed of 50-80g / s (injection volume = mold volume × foaming ratio × 1.05, foaming ratio 30-40 times). After sealing, foam at 45-55℃ for 15-20min (mold pressure 0.3-0.5MPa). Demold after curing degree ≥95%, check the core layer for bubbles and cracks, and ensure flatness ≤0.3mm / m. If qualified, proceed to the next process.

[0076] S4-3: Sealing groove processing: Using a carbide end mill, process a 45° inclined sealing groove 17 (groove width 5-8mm, groove depth 3-5mm, error ±0.05mm) at the edge of the core layer at a speed of 800-1000r / min and 50-80mm / min. After wet grinding the groove wall with 800-grit sandpaper, check the closed-cell rate ≥96% and the thermal conductivity ≤0.021W / (m·K). After passing the test, the modified polyurethane core layer 4 is obtained and marked for later use.

[0077] S5-1: Bottom Layer Composite: Fix the lower composite corrosion-resistant surface layer with the interlocking adhesive reinforcement layer (positioning accuracy ±0.05mm), with the interlocking groove facing upwards. Align the 19 protrusions of the second reinforcement layer with the interlocking groove. Use CCD visual positioning (±0.03mm) to ensure misalignment error ≤0.05mm. Apply hot pressing at 0.8-1.0MPa and 60-70℃ for 15-20min (segmented pressure: 0.5MPa preheating for 5min, then pressurizing and holding). After cooling to 25±2℃, test the bonding strength. If there is no delamination or debonding, the lower composite layer is obtained for later use.

[0078] S5-2: Core Layer Composite: Apply 0.5-1.0 mm thick polyurethane hot melt adhesive (error ±0.1 mm) to the upper and lower surfaces of the modified polyurethane core layer 4 at a speed of 5-8 m / min. The lower surface is bonded to the second reinforcing layer 19 of the lower composite layer (edge ​​misalignment ≤0.1 mm). Hot melt bonding is performed at 80-90℃ and 0.5-0.6 MPa for 10-15 min. The first reinforcing layer 18 is bonded to the upper surface. CCD positioning ensures symmetry with the second reinforcing layer 19 (error ≤0.05 mm). The hot melt bonding process is repeated. After cooling, the bonding strength is tested to be ≥1.2 MPa. After passing the test, it is ready for use.

[0079] S5-3: Upper layer composite: With the interlocking groove of the upper composite corrosion-resistant surface layer 5 with the upper interlocking adhesive reinforcement layer 13 facing down, it is connected to the boss of the first reinforcement layer 18 of the core layer-double reinforcement layer composite structure. Positioning ensures that the boss is aligned with the interlocking groove and the upper and lower reinforcing ribs (misalignment ≤ 0.1mm). Repeat the hot pressing interlocking process of S5-1. After cooling, check that each layer is tightly bonded and there are no delamination gaps to obtain the composite structure.

[0080] S6: Fixing construction of scaly layer 3

[0081] S6: Fixing of the Scale-like Sheet Layer 3: Scale-like zinc-aluminum alloy sheets are selected, with a sheet thickness of 0.1-0.2 mm and a scale size of 5-8 mm. The surface is modified with silane coupling agent KH-550. Using specialized adhesive application equipment, the epoxy-modified adhesive is evenly coated onto the back of the sheet, with a coating thickness of 5-8 μm (error ±0.5 μm). Immediately after coating, the sheet is evenly laid on the surface of the composite structure, with an overlap width of 1-2 mm and an overlap error ≤0.1 mm. It is then fixed by light pressure with a roller (pressure 0.2-0.3 MPa). After laying, it is placed in a constant temperature curing chamber and cured at 70-80℃ for 20-30 minutes. After curing, the adhesion of the sheet is tested to ensure there is no loosening or peeling, and the sheet is laid flat without curling edges. Once qualified, it proceeds to the next process.

[0082] S7: All-around corrosion-resistant sealing molding

[0083] S7: All-round corrosion-resistant sealing molding: Environmentally friendly polysulfide sealant is selected, with a viscosity of 1800-2200 mPa·s at 25℃. A high-precision dispensing gun is used to evenly inject the sealant into the sealing groove 17 at the edge of the core layer and the joints between each layer. The thickness of the sealant is 3-5mm and the width is 5-8mm, ensuring that the sealant fills the gaps completely, without air bubbles or gaps. After dispensing, the surface of the sealant is smoothed with a scraper to make it flush with the surface of the structure. Then, it is allowed to cure at room temperature (25±2℃) for 4-6 hours. After the degree of curing is ≥90%, the sealing effect is inspected with a magnifying glass to ensure that there are no leaks or cracks, and that the sealing layer adheres tightly to each layer, forming an all-round corrosion-resistant sealing structure.

[0084] S8: Finished Product Inspection and Cutting

[0085] S8-1: Performance Testing: 10 products are randomly selected from each batch. Testing items and standards: ① Neutral salt spray test for 1000 hours (5% NaCl, 35℃, 0.1-0.2MPa), no rust, coating peeling, or sealing failure; ② Bending strength ≥15MPa, impact strength ≥20J / cm², tensile strength ≥10MPa; ③ No water leakage after 24 hours of 0.3MPa water pressure, no medium penetration after 72 hours of 5% hydrochloric acid immersion; ④ Thermal conductivity ≤0.021W / (m·K); ⑤ Overall dimensional error ≤±0.1mm, flatness ≤0.2mm / m; ⑥ No loose scales, cracked sealing layer, surface scratches or stains. Defective products are reworked, while qualified products proceed to the next process.

[0086] S8-2: Precision Cutting: Based on usage requirements, a carbide cutting blade (blade sharpness ≤0.01mm) is used for CNC cutting at 3-5m / min and 0.8-1.0MPa pressure, with a positioning accuracy of ±0.05mm, ensuring a smooth, burr-free cut. After cutting, the cut is wet-ground with 800-grit sandpaper (corner radius 0.5mm), and environmentally friendly, corrosion-resistant sealant is applied to the edges (thickness 1-2mm, width 5mm). After 2 hours of curing and passing inspection, the cut is marked with the serial number, specifications, and production date and stored for future use.

[0087] unit Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Core layer foaming ratio - 35 34 36 37 33 38 Hot pressing composite pressure MPa 0.90 0.88 0.92 0.95 0.85 0.98 neutral salt spray test h 490 970 990 1010 320 450 flexural strength MPa 7.9 8.0 8.1 14.8 5.8 7.0 Tensile strength MPa 5.9 6.0 5.8 9.9 3.9 5.5 thermal conductivity W / (m·K) ≤0.025 ≤0.024 ≤0.025 ≤0.021 ≤0.027 ≤0.025

[0088] Comparative Examples 1 and 2 both adopt a basic three-layer composite structure, specifically a color steel plate surface layer, a polyurethane core layer, and a bottom layer directly bonded together. No flake-like protective layer or fully sealed structure is set, and no pretreatment is performed on the interlayer interface. The core process parameters have significant deviations.

[0089] In Comparative Example 1, the polyurethane core layer foaming agent used was a common polyether polyol foaming system. The amount of foaming agent added was 8% of the total mass of the core layer, resulting in a core layer foaming ratio of only 28 times. The interlayer hot-pressing composite pressure was set at 0.3 MPa, the hot-pressing temperature was controlled at 150℃, the hot-pressing time was 3 min, the foaming temperature was 18℃, and the raw material mixing uniformity was only 82%.

[0090] Furthermore, no anti-aging agent was added to the core layer. Comparative Example 2 used the same foaming system as Comparative Example 1, but the amount of foaming agent added was increased to 18% of the total mass of the core layer, resulting in a foaming ratio of up to 45 times. The interlayer hot-pressing composite pressure was set to 0.8 MPa, the hot-pressing temperature was 170℃, the hot-pressing time was 5 min, the foaming temperature was 25℃, the raw material mixing uniformity was 80%, and no anti-aging agent was added. Moreover, the core layer thickness was not precisely controlled, resulting in localized over-thickness.

[0091] Example 4 employs a composite structure, featuring a flake-like protective layer and a fully sealed structure. The flake-like protective layer is made of epoxy zinc-rich flake coating with a thickness of 80 μm. The presence of the flake-like protective layer prevents the polyurethane color steel plate of Example 4 from directly contacting the external environment, while also providing corrosion resistance and load dispersion for the polyurethane color steel plate itself. This improves the strength and corrosion resistance of Example 4.

[0092] The fully sealed structure uses polyurethane sealant to fill the gaps between layers. The core layer foaming agent is a modified polyether polyol foaming system, with an addition amount of 12% of the total mass of the core layer. The foaming ratio of the core layer is controlled at 36 times. The interlayer hot-pressing composite pressure is set at 0.5 MPa, the hot-pressing temperature is 160℃, the hot-pressing time is 4 min, the foaming temperature is controlled at 22℃, the raw material mixing uniformity reaches 95%, and 0.5% anti-aging agent is added to the core layer. Therefore, the corrosion resistance of the polyurethane color steel plate in this application is better than that of Comparative Example 1 and Comparative Example 2.

[0093] In terms of mechanical properties, Comparative Example 1 suffered from insufficient foaming agent dosage, low hot-pressing pressure (0.3 MPa), and short hot-pressing time (3 min), resulting in insufficient core layer density, small and unevenly distributed cell size, untreated interlayer interfaces, loose bonding, obvious gaps, and weak mechanical support. Its bending strength was only 8.2 MPa and its tensile strength was 12.5 MPa.

[0094] Furthermore, no anti-aging agent was added to the core layer, resulting in poor long-term mechanical stability. In Comparative Example 2, due to excessive foaming agent (reaching 18% of the total mass of the core layer), excessively high hot-pressing pressure (0.8 MPa), and excessively high hot-pressing temperature (170℃), the core layer was over-foamed, resulting in excessively large pores and some interconnected cells, leading to a loose structure. At the same time, the excessively high hot-pressing pressure caused plastic deformation of the core layer, and the local thickness of the core layer further aggravated the uneven mechanical properties, resulting in a further decline in mechanical properties. The flexural strength was 7.9 MPa and the tensile strength was 11.8 MPa, also showing the problem of insufficient long-term mechanical stability.

[0095] In comparison, Example 4 enhances the overall structural rigidity of the board with a flake-like protective layer (epoxy zinc-rich flake coating, 80μm thick), improves the interlayer bonding stability with a fully sealed structure (filled with polyurethane sealant), and has a reasonable amount of foaming agent added to the core layer (12%). The foaming ratio is reasonably matched with the hot-pressing composite pressure, hot-pressing temperature and time to ensure that the core layer structure is dense and the pore distribution is uniform. At the same time, the addition of an anti-aging agent to the core layer further improves the mechanical stability, thereby obtaining a bending strength of 13.6MPa and a tensile strength of 18.2MPa, which are 65.85% and 72.15% higher than those of Comparative Examples 1 and 2, and 45.60% and 54.24% higher, respectively.

[0096] In terms of thermal insulation performance, Comparative Example 1 had insufficient foaming agent in the core layer and a low foaming temperature (18℃), resulting in insufficient foaming of the core layer, low porosity (only 65%), insufficient thermal insulation channels, low heat transfer resistance, and a high thermal conductivity (0.032W / (m·K). Furthermore, it did not have a fully sealed structure, and air convection was likely to occur between the layers, further reducing the thermal insulation effect. Comparative Example 2 had excessive foaming agent in the core layer and a high foaming temperature (25℃), resulting in excessive foaming of the core layer, excessively large pores (average pore diameter of 1.2mm), and partial interconnection.

[0097] Heat is easily transferred rapidly through interconnected pores and air convection, further increasing the thermal conductivity to 0.035 W / (m·K). Simultaneously, the localized thickness of the core layer leads to uneven heat distribution, significantly reducing insulation performance. In Example 4, due to the reasonable dosage of foaming agent in the core layer, the foaming temperature controlled at 22℃, the porosity controlled at 80%, and the moderate pore size (average pore diameter 0.6 mm) and uniform distribution, heat transfer can be effectively blocked.

[0098] Meanwhile, the fully sealed structure (filled with polyurethane sealant) avoids the heat conduction loss caused by air convection in the interlayer gaps. The anti-aging agent added to the core layer can prevent the thermal insulation performance from declining due to the aging of the core layer structure during long-term use. The thermal conductivity is controlled within a reasonable range of 0.026 W / (m·K), which is 18.75% and 25.71% lower than that of comparative examples 1 and 2, respectively.

[0099] In terms of corrosion resistance, Comparative Examples 1 and 2 did not have a flake-like protective layer or a fully sealed structure, and the surface layer was not treated with anti-corrosion. There were gaps between the layers, and corrosive media (salt spray, water vapor) could easily penetrate into the core layer through the gaps between the layers. In addition, no anti-aging agent was added to the core layer, and the polyurethane core layer was prone to degradation and powdering, resulting in structural damage. Among them, Comparative Example 1 had a relatively small gap between the layers, and the neutral salt spray test time was only 180 hours. Comparative Example 2 had a core layer with excessively large pores and a loose structure, making it easier for corrosive media to penetrate.

[0100] The neutral salt spray test duration was only 160 hours, and both showed varying degrees of surface blistering and interlayer debonding. The flake-like protective layer (epoxy zinc-rich flake coating) in Example 4 effectively blocked the intrusion of corrosive media, forming a dense anti-corrosion barrier. The fully sealed structure completely isolated salt spray and water vapor from contact with the core layer and interlayer interfaces. The anti-aging agent added to the core layer slowed down its degradation rate. The surface layer underwent phosphating anti-corrosion treatment, further enhancing its anti-corrosion performance. The neutral salt spray test duration reached 280 hours, extending by 55.56% and 75.00% compared to Comparative Examples 1 and 2, respectively, without any surface blistering or interlayer debonding.

[0101] In summary, Comparative Examples 1 and 2 lack a flake-like protective layer, a fully sealed structure, and surface anti-corrosion treatment. The core layer also lacks anti-aging agents, and the core process parameters deviate from reasonable ranges. Therefore, they are weaker than Example 4 in terms of mechanical properties, corrosion resistance, and service life.

[0102] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An environmentally friendly and corrosion-resistant polyurethane color steel plate, characterized in that, It includes an upper composite corrosion-resistant surface layer (5), an upper interlocking adhesive reinforcement layer (13), a first reinforcement layer (18), a modified polyurethane core layer (4), a second reinforcement layer (19), a lower interlocking adhesive reinforcement layer and a lower composite corrosion-resistant surface layer. The modified polyurethane core layer (4) has a sloping sealing groove (17) at its edge. A fluororubber sealing strip (6) is embedded in the sealing groove and filled with sealant. The corner of the color steel plate is provided with aluminum alloy corner protectors (1), and rivets (2) are riveted on the aluminum alloy corner protectors (1). The gaps between the structural layers of the corner of the color steel plate are filled with environmentally friendly corrosion-resistant sealant. The upper composite corrosion-resistant surface layer (5) and the lower composite corrosion-resistant surface layer are symmetrical in structure. The upper composite corrosion-resistant surface layer (5) and the lower composite corrosion-resistant surface layer both include a substrate (10), an epoxy transition layer (7), a fluorocarbon anti-corrosion layer (8) and trapezoidal reinforcing ribs (9). The surface of the substrate (10) is provided with honeycomb micro-concave (11).

2. The environmentally friendly and corrosion-resistant polyurethane color steel plate according to claim 1, characterized in that, Both the upper interlocking adhesive reinforcement layer (13) and the lower interlocking adhesive reinforcement layer include a modified adhesive, micro bumps (12) and rectangular interlocking grooves (14). The micro bumps (12) are precisely fitted with the honeycomb-shaped micro-concaves (11) of the substrate (10). The rectangular interlocking grooves (14) are nested with the rectangular bosses (15) of the reinforcement layer. The nesting gap between the rectangular interlocking grooves (14) and the rectangular bosses (15) of the reinforcement layer is less than or equal to 0.05 mm. The modified adhesive is prepared by mixing bisphenol A type epoxy resin and polyamide 650 curing agent in a mass ratio of 4:

1. The modified adhesive contains 0.8-1.0 wt% silane coupling agent and 0.3-0.5 wt% titanium dioxide corrosion-resistant filler.

3. The environmentally friendly and corrosion-resistant polyurethane color steel plate according to claim 1, characterized in that, The first reinforcing layer (18) and the second reinforcing layer (19) have the same structure. The first reinforcing layer (18) and the second reinforcing layer (19) include a glass fiber reinforced epoxy resin substrate, a rectangular boss (15), a diamond-shaped reinforcing texture (16) and an epoxy anti-corrosion coating. The substrate is formed by hot pressing epoxy resin liquid impregnated with alkali-free glass fiber cloth. The epoxy anti-corrosion coating is an epoxy zinc-rich primer with a zinc content ≥80%.

4. The environmentally friendly and corrosion-resistant polyurethane color steel plate according to claim 1, characterized in that, The modified polyurethane core layer (4) is made by mixing isocyanate and polyol in a mass ratio of 1.1:1, and the modified polyurethane core layer (4) is made by adding composite flame retardant, organosilane coupling agent and basalt reinforcing fiber.

5. A processing method for an environmentally friendly and corrosion-resistant polyurethane color steel plate as described in any one of claims 1-4, characterized in that, include: S1: Prepare the upper composite corrosion-resistant surface layer (5) and the lower composite corrosion-resistant surface layer, and successively go through the substrate treatment, coating preparation and reinforcing rib forming process; The substrate (10) is made of AZ150 grade zinc-aluminum-magnesium substrate (10) with a thickness of 0.5-0.7mm. It is subjected to environmentally friendly alkaline degreasing, dilute hydrochloric acid pickling, sodium carbonate solution neutralization, segmented hot air drying and fiber laser micro-engraving in sequence. After drying, the moisture content of the substrate (10) does not exceed 0.1%. Laser micro-engraving is used to process hexagonal honeycomb micro-concave (11). After micro-engraving, the coating is cleaned by high-pressure air and inspected by a magnifying glass to ensure it is qualified. The coating is prepared by high-pressure electrostatic spraying machine, and epoxy transition layer (7) and fluorocarbon anti-corrosion layer (8) are applied in sequence. After constant temperature curing, the coating adhesion is tested by cross-cut test to ensure that there is no peeling. The reinforcing rib is formed by multiple sets of cold bending and rolling machine to process trapezoidal reinforcing rib (9). After rolling, it is leveled by a leveling machine. The positioning fixture is used to ensure that the reinforcing ribs of the upper and lower composite corrosion resistant surface are accurately aligned and the misalignment error does not exceed 0.1mm. After passing the inspection, they are paired for use. S2: The upper interlocking adhesive reinforcement layer and the lower interlocking adhesive reinforcement layer are prepared by sequentially performing adhesive preparation, layer forming, and interlocking groove processing steps; The binder is prepared by mixing bisphenol A epoxy resin, polyamide curing agent, acetone diluent, KH-550 silane coupling agent and nano titanium dioxide corrosion-resistant filler in a certain proportion, and then mixing at high speed, cooling in a water bath, and letting it stand to defoam before use. The layer forming is carried out using a stainless steel scraper coating machine to apply the modified adhesive to the non-reinforcing rib surface of the upper and lower composite corrosion-resistant surface layers. Simultaneously, micro protrusions (12) that precisely match the honeycomb micro-concave (11) are formed. After coating, the layer is pre-dried at a constant temperature to ensure that the adhesive is initially formed and does not stick. After the adhesive has cured to 60%-70%, the interlocking groove is processed by carbon dioxide laser engraving process to process the rectangular interlocking groove (14). After engraving, the groove is cleaned by high pressure air and the dimensional accuracy is checked by calipers. After passing the test, the groove is integrated with the composite corrosion-resistant surface layer to form an integrated structure for later use. S3: Prepare the first reinforcing layer (18) and the second reinforcing layer (19) in sequence through substrate molding, boss and reinforcing texture processing, and anti-corrosion coating process; wherein the substrate molding uses alkali-free glass fiber cloth, which is impregnated with epoxy resin and then vacuum hot-pressed and cooled for testing to ensure that the layer strength meets the standard. The boss and reinforcing pattern are processed by fiber laser cutting technology to ensure that the rectangular boss and the rectangular interlocking groove (14) are accurately matched without overcutting or missing cutting, and the diamond reinforcing pattern is regular and burr-free; the anti-corrosion coating is applied by a high-precision roller coating machine, and epoxy zinc-rich primer is applied to the upper and lower surfaces of the reinforcing layer. After constant temperature curing, the adhesion is tested by cross-cut test and the corrosion resistance is tested by neutral salt spray test. After passing the test, it is ready for use. S4: Prepare the modified polyurethane core layer (4), which is successively processed by raw material preparation, foaming and molding, and sealing groove processing. The raw material preparation mixes isocyanate MDI-50, polyol POP-3628 and various modifiers in proportion, and after high-speed stirring and water bath cooling, it is filtered through a 300-mesh stainless steel filter screen for later use. The foaming molding process uses a high-pressure foaming machine to inject the raw material into a preheated custom steel mold, controlling the foaming ratio to 30-40 times. After foaming, the mold is demolded under constant temperature curing to ensure that the core layer surface is free of defects. The sealing groove is processed by CNC milling. A 45° inclined sealing groove (17) is processed on the edge of the core layer. After milling, the burrs are removed by wet sanding with water sandpaper. The closed-cell rate, thermal conductivity and sealing groove size of the core layer are tested. After passing the test, it is ready for use. S5: Each structural layer is composited layer by layer, and double fixation is achieved through hot pressing interlocking process and hot melt bonding process; First, the lower composite corrosion resistant surface layer and the second reinforcing layer (19) are fixed by hot pressing interlocking process after CCD visual positioning. The hot pressing pressure is 0.8-1.0MPa, the temperature is 60-70℃, and the time is 15-20min. The segmented pressurization method is used to ensure tight interlocking. Then, the modified polyurethane core layer (4) is fixed to the lower composite layer and the first reinforcing layer (18) by hot melt bonding process. The bonding temperature is 80-90℃ and the pressure is 0.5-0.6MPa to ensure that the reinforcing layer is symmetrical and there is no core layer deformation. Finally, the upper composite corrosion-resistant surface layer (5) is fixed to the first reinforcing layer (18) by repeating the above hot pressing bonding process to ensure that there is no delamination, no gaps and no delamination of each structural layer. S6: Fix the scale-like sheet layer (3) on the outer surface of the color steel plate. The process steps and parameters are completely consistent with S4 in this embodiment 2. After the sheet is fixed, the edge is treated and the curing test is performed, it is ensured that the sheet is not loose or falls off. S7: Perform all-round corrosion-resistant sealing. The process steps and parameters are completely consistent with S5 in this embodiment 3. The process includes side sealing, corner sealing, interface sealing, and overall curing to ensure that there are no omissions or bubbles in the seal and that the degree of curing meets the standard. S8: Finished product inspection and cutting. After passing the inspection, the cut edges are sealed. For finished product inspection, 10 products are randomly selected from each batch. The inspection items include corrosion resistance, structural strength, sealing performance, heat insulation performance, dimensional accuracy, and appearance quality. Unqualified products are reworked. Cutting is carried out using CNC cutting equipment according to actual needs. After the cut edges are wet sanded with sandpaper, they are coated with environmentally friendly corrosion-resistant sealant and sealed. After static curing, they are inspected again. After passing the inspection, the product number, specifications, and production date are marked and stored for future use.

6. The processing method of an environmentally friendly and corrosion-resistant polyurethane color steel plate according to claim 5, characterized in that, The substrate processing in step S1 includes degreasing, pickling, neutralization, drying and laser micro-engraving. The laser micro-engraving process forms a regular hexagonal honeycomb-shaped micro-recess (11), with the pit diameter being 0.8-1.2 mm and the depth being 0.3-0.5 mm.

7. The method for producing an environmentally friendly and corrosion-resistant polyurethane color steel plate according to claim 5, characterized in that, In step S7, the side sealing adopts a combination of fluororubber sealing strip (6) and secondary injection. The fluororubber sealing strip (6) has a temperature resistance range of -40℃ to 150℃ and a corrosion resistance grade of C4. The corners of the fluororubber sealing strip (6) are sealed with 6061 aluminum alloy corner protectors (1) by applying glue and riveting. The riveting pressure is 1.0-1.2MPa and the riveting spacing is 50-80mm. The whole is cured by standing for 12-24h at a temperature of 25±2℃ and a humidity of 40%-50%, and the degree of curing is ≥98%.

8. The method for producing an environmentally friendly and corrosion-resistant polyurethane color steel plate according to claim 5, characterized in that, In step S6, the scaly sheet is made of 316L stainless steel micro-sheets or alumina ceramic micro-sheets with a thickness of 0.1-0.2mm. After laser cutting, grinding, cleaning and drying, the edge radius of the sheet is 0.1-0.2mm. It is double fixed by epoxy dispensing and edge embedding, and the curing degree of the sealant is ≥98%.

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