Corrosion-resistant color-coated sheet based on EB curing technology and preparation method of corrosion-resistant color-coated sheet

Abstract

The invention discloses a corrosion-resistant color-coated sheet based on an EB curing technology and a preparation method of the corrosion-resistant color-coated sheet. One surface or two surfaces of a steel plate are sequentially coated with a primer layer and an EB finish paint layer; eB curing coating adopted by the EB finish paint layer comprises, by weight, 60%-70% of resin, 5%-15% of reactive diluent, 10%-20% of pigment filler, 1%-8% of functional filler and 1%-5% of additive. By optimizing the formula of the coating and adopting a gradient curing process, the curing time is shortened to be within 1 second, the comprehensive energy consumption is reduced by 30%, and meanwhile, nearly zero emission of VOCs is achieved; the corrosion resistance of the color-coated sheet is obviously improved, and the salt spray resistance of the composite coating can reach more than or equal to 1000 hours; based on accurate control of electron beam radiation parameters, uniform curing of a coating is realized, and stability and consistency of product quality are improved; the production efficiency of the color-coated sheet can be effectively improved, the product quality is ensured, meanwhile, environmental pollution is reduced, and the requirements of the modern manufacturing industry for the efficient and environment-friendly production technology are met.

Description

Technical Field

[0001] This invention relates to the field of color-coated steel sheet production technology, and in particular to a corrosion-resistant color-coated steel sheet based on EB curing technology and its preparation method. Background Technology

[0002] Traditional color-coated steel sheet production processes rely on thermosetting or UV curing technologies, which suffer from high energy consumption, VOC emissions, and slow curing speeds. Furthermore, the corrosion resistance of the coating is limited by the simplistic formulation. While existing low-energy electron beam (EB) curing technologies are environmentally friendly, they generally suffer from insufficient coating adhesion, poor corrosion resistance, and low process compatibility. In addition, the wide range of parameters for electron beam curing (EB curing) in existing technologies (e.g., energy 70–150 keV) lacks precise control for different substrates, leading to unstable coating performance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a corrosion-resistant color-coated steel sheet based on EB curing technology; the present invention also provides a method for preparing a corrosion-resistant color-coated steel sheet based on EB curing technology.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a primer layer and an EB topcoat layer are sequentially coated on one or both sides of the steel plate; The weight composition of the EB curing coating used in the EB topcoat layer is as follows: 60%–70% resin, 5%–15% reactive diluent, 10%–20% pigments and fillers, 1%–8% functional fillers, and 1%–5% additives.

[0005] Furthermore, the resin is an acrylic-modified epoxy resin or a polyurethane resin, and the reactive diluent is an alkoxyacrylate.

[0006] Furthermore, the pigments and fillers are selected from titanium dioxide and composite metal oxides; the functional fillers are nano-silica to improve mechanical properties; the additives include leveling agents and / or stabilizers, and the stabilizers are preferably UV stabilizers.

[0007] Furthermore, the primer layer adopts a double-layer primer structure of epoxy zinc-rich primer layer + transition layer, and the transition layer adopts epoxy resin and nano aluminum oxide.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the method of the present invention includes the following steps: 1) applying a primer to the surface of the steel plate; 2) Dry the steel plate coated with primer to form a primer layer; 3) Apply EB curing coating to the primer layer of the dried steel plate; 4) Gradient EB curing is performed on the EB curing coating; the gradient EB curing adopts three-stage energy regulation, with energy of 80-100 keV, 100-120 keV and 120-150 keV respectively, total dose of 60-80 KGy, and irradiation time of 400-800 ms.

[0009] Furthermore, in step 2), the baking temperature during the drying process is 180℃~240℃.

[0010] Furthermore, in step 1), the steel plate undergoes passivation treatment before the primer is applied.

[0011] Furthermore, in step 2), embossing or printing can be performed on the primer layer.

[0012] The beneficial effects of adopting the above technical solution are as follows: 1. High efficiency, energy saving and environmental protection: This invention optimizes the coating formula and adopts a gradient curing process, which shortens the curing time to less than 1 second, reduces the overall energy consumption by 30%, and achieves near-zero VOCs emissions. 2. Excellent corrosion resistance: This invention significantly improves the corrosion resistance of color-coated steel sheets. According to GB / T 13448-2019 standard, the salt spray resistance of the composite coating reaches ≥1000 hours. 3. Controllable quality: This invention achieves uniform curing of the coating based on precise control of electron beam radiation parameters, thereby improving the stability and consistency of product quality; This invention can effectively improve the production efficiency of color-coated steel sheets, ensure product quality, and reduce environmental pollution, thus meeting the needs of modern manufacturing for efficient and environmentally friendly production technologies. Detailed Implementation

[0013] This invention relates to a corrosion-resistant color-coated steel sheet based on EB curing technology, comprising a steel plate, a primer layer, and an EB topcoat layer; the primer layer and the EB topcoat layer are sequentially coated on one or both sides of the steel plate. The steel plate is made of cold-rolled steel or galvanized steel, with a thickness of 0.8–1.0 mm. The primer layer adopts a double-layer primer structure of epoxy zinc-rich primer layer + transition layer; the dry film thickness of the epoxy zinc-rich primer layer is 8–10 μm; the coating of the transition layer is made of epoxy resin and nano-alumina, with a dry film thickness of 2–3 μm. The EB topcoat layer is formed by EB curing of the EB-cured coating, with a wet film thickness of 15–25 μm. The primer layer may be embossed with a pattern or printed with a pattern.

[0014] The EB-cured coating comprises, by weight: 60%–70% resin, 5%–15% reactive diluent, 10%–20% pigments and fillers, 1%–8% functional fillers, and 1%–5% additives. The resin is acrylic-modified epoxy resin or polyurethane resin; the reactive diluent is alkoxyacrylate; and the pigments and fillers are titanium dioxide. The functional fillers are nano-silica to improve mechanical properties. The additives include leveling agents and / or stabilizers, preferably UV stabilizers.

[0015] The preparation method of this corrosion-resistant color-coated steel sheet based on EB curing technology includes the following steps: 1) Substrate pretreatment: The steel plate to be coated is passivated, then cleaned and dried to remove impurities such as oil and rust, and improve the adhesion of the coating; the passivation treatment is degreasing → water washing → phosphating or chromating.

[0016] 2) Primer application: Apply primer to the cleaned steel plate surface, either on one or both sides. The primer layer adopts a double-layer structure consisting of an epoxy zinc-rich primer layer and a transition layer. First, apply the epoxy zinc-rich primer layer with a dry film thickness of 8–10 μm. After drying, apply the transition layer with a dry film thickness of 2–3 μm. The transition layer is composed of epoxy resin and nano-alumina, with a mass ratio of 85%–87% epoxy resin and 15%–13% nano-alumina.

[0017] 3) Primer baking: The steel plate coated with primer is dried to form a primer layer; the drying temperature is 180-240℃ and the baking time is 40-50s.

[0018] 4) Embossing / Printing: Embossing or printing is performed on the surface of the primer layer to form a customized pattern. This step is optional and can be omitted. The main components of the printing ink are (wt): 40-60% acrylic resin, 15-30% pigment, and 5-10% nano-silica, with a printing resolution ≥1200dpi.

[0019] 5) Apply EB curing coating: Apply EB curing coating to the surface of the primer layer by roller coating, spraying or curtain coating, with a wet film thickness of 15-25μm.

[0020] 6) EB Curing: The EB curing coating is subjected to gradient EB curing to form an EB topcoat layer. The gradient EB curing adopts a three-stage gradient energy control: the first stage energy is 80-100 keV, the second stage energy is 100-120 keV, and the third stage energy is 120-150 keV, with a total dose of 60-80 kGy and a total irradiation time of 400-800 ms. The irradiation time distribution is: 40%-60% in the first stage, 30-40% in the second stage, and 10-25% in the third stage. Preferably, the energy is sequentially 100 keV / 30 kGy → 120 keV / 25 kGy → 150 keV / 20 kGy, with a total irradiation time of 600 ms.

[0021] 7) After adopting the above method, the curing time is shortened to less than 1 second, the overall energy consumption is reduced by 30%, and VOCs emissions are close to zero, which can effectively improve efficiency and environmental protection; the salt spray resistance of the composite coating is ≥2000 hours (ISO 9227), which is 50% higher than the traditional process, effectively improving corrosion resistance; by precisely controlling the radiation parameters of the electron beam, uniform curing of the coating can be achieved, improving the stability and consistency of product quality, and ensuring stable product quality. Example 1

[0022] 1) Substrate pretreatment: Use cold-rolled steel plates with a thickness of 1.0mm, check for any defects, and ensure that the surface of the steel plate is flat; the surface of the steel plate is degreased, washed with water, phosphated, washed with water, and dried.

[0023] 2) Primer application: The first layer uses epoxy zinc-rich primer with a dry film thickness of 8μm; the transition layer uses 85% epoxy resin and 15% nano alumina with a thickness of 2μm.

[0024] 3) Primer baking: The steel plate coated with primer is placed in an oven and baked at 180°C for 50 seconds to form the primer layer.

[0025] 4) Digital inkjet printing: Printing customized patterns on the primer layer.

[0026] 5) Apply EB curing coating: Apply EB curing coating to the surface of the primer layer. The wet film thickness is 20μm. The coating formula is: 60% acrylic modified epoxy resin, 12% acrylic alkoxy ester reactive diluent, 18% titanium dioxide, 5% nano silica, 2% leveling agent, and 3% UV stabilizer.

[0027] 6) EB curing: The coated steel plate is fed into an electron beam curing device. The electron beam energy is set to three stages: 100→120→150 keV, total dose 75 kGy, dose of each stage 30 kGy→25 kGy→20 kGy, total irradiation time 600 ms, irradiation time of each stage 240 ms→210 ms→150 ms.

[0028] 7) The corrosion-resistant color-coated steel sheet obtained in this embodiment was tested, and its salt spray resistance was 1700 hours (GB / T 13448-2019). Other test results are shown in Table 1. Table 1: Test Results of Example 1 . Example 2

[0029] 1) Substrate pretreatment: Use 0.8mm thick galvanized steel sheet, check for any defects, and ensure that the steel sheet surface is flat; perform degreasing-water washing-chromizing-water washing-drying treatment on the steel sheet surface.

[0030] 2) Primer coating: First layer: epoxy zinc-rich layer, dry film thickness 8μm; Second layer: transition layer, containing 87% epoxy resin and 13% nano aluminum oxide, dry film thickness 3μm.

[0031] 3) Primer baking: The steel plate coated with primer is placed in an oven and dried at 240℃ for 40 seconds to form a primer layer.

[0032] 4) Apply EB curing coating: Apply EB curing coating to the surface of the primer layer. The wet film thickness is 15μm. The coating formula is: 70% polyurethane resin, 8% alkoxy acrylate, 15% titanium dioxide, 4% nano silica, and 3% leveling agent.

[0033] 5) EB curing: The coated steel plate is sent into the electron beam curing device. The electron beam energy is set to 80→100→120KeV, the total dose is 65KGy, the dose of each stage is 35KGy→20KGy→10KGy, the total irradiation time is 500ms, and the irradiation time of each stage is 225ms→175ms→100ms.

[0034] 6) The corrosion-resistant color-coated steel sheet obtained in this embodiment was tested, and the salt spray resistance test result was 1800 hours (ISO9227 standard). Other test results are shown in Table 2. Table 2: Test Results of Example 2 . Example 3

[0035] 1) Substrate pretreatment: Use zinc-aluminum-magnesium steel plate with a thickness of 0.8mm, check for any defects and ensure that the surface of the steel plate is flat; the surface of the steel plate is degreased, washed with water, chromized, washed with water and dried.

[0036] 2) Primer coating: First layer: epoxy zinc-rich layer, dry film thickness 10μm; Second layer: transition layer, containing 86% epoxy resin and 14% nano aluminum oxide, dry film thickness 2.5μm.

[0037] 3) Primer baking: The steel plate coated with primer is placed in an oven and dried at 200℃ for 45 seconds to form a primer layer.

[0038] 4) Apply EB curing coating: Apply EB curing coating to the surface of the primer layer. The wet film thickness is 25μm. The coating formula is: 69% polyurethane resin, 5% alkoxy acrylate, 20% titanium dioxide, 1% nano silica, 2% leveling agent and 3% UV stabilizer.

[0039] 5) EB curing: The coated steel plate is fed into the electron beam curing device. The electron beam energy is set to 90→110→140KeV, the total dose is 80KGy, the dose of each stage is 35KGy→25KGy→20KGy, the total irradiation time is 800ms, and the irradiation time of each stage is 320ms→280ms→200ms.

[0040] 6) The corrosion-resistant color-coated steel sheet obtained in this embodiment was tested, and the salt spray resistance test result was 1600 hours (ISO9227 standard). Other test results are shown in Table 3. Table 3: Detection Results of Example 3 . Example 4

[0041] 1) Substrate pretreatment: Use 1.0mm thick galvanized steel sheet, check for any defects, and ensure that the steel sheet surface is flat; perform degreasing-water washing-phosphating-water washing-drying treatment on the steel sheet surface.

[0042] 2) Primer coating: First layer: epoxy zinc-rich layer, dry film thickness 9μm; Second layer: transition layer, containing 85% epoxy resin and 15% nano aluminum oxide, dry film thickness 2μm.

[0043] 3) Primer baking: The steel plate coated with primer is placed in an oven and dried at 220℃ for 42 seconds to form a primer layer.

[0044] 4) Apply EB curing coating: Apply EB curing coating to the surface of the primer layer. The wet film thickness is 18μm. The coating formula is: 66% polyurethane resin, 15% alkoxy acrylate, 10% titanium dioxide, 8% nano silica, and 1% leveling agent.

[0045] 5) EB curing: The coated steel plate is fed into the electron beam curing device. The electron beam energy is set to 85→110→130KeV, the total dose is 60KGy, the dose of each stage is 35KGy→15KGy→10KGy, the total irradiation time is 400ms, and the irradiation time of each stage is 240ms→120ms→40ms.

[0046] 6) The corrosion-resistant color-coated steel sheet obtained in this embodiment was tested, and the salt spray resistance test result was 1350 hours (ISO9227 standard). Other test results are shown in Table 4. Table 4: Detection Results of Example 4 .

[0047] The above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. In addition to the above embodiments, the present invention may have other implementations. Any modifications or equivalent substitutions to the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A corrosion-resistant color-coated steel sheet based on EB curing technology, characterized in that: A primer layer and an EB topcoat layer are sequentially applied to one or both sides of the steel plate; The weight composition of the EB curing coating used in the EB topcoat layer is as follows: 60%–70% resin, 5%–15% reactive diluent, 10%–20% pigments and fillers, 1%–8% functional fillers, and 1%–5% additives.

2. The corrosion-resistant color-coated steel sheet based on EB curing technology according to claim 1, characterized in that: The resin is an acrylic-modified epoxy resin or a polyurethane resin, and the reactive diluent is an alkoxy acrylate.

3. The corrosion-resistant color-coated steel sheet based on EB curing technology according to claim 1, characterized in that: The primer layer adopts a double-layer primer structure of epoxy zinc-rich primer layer + transition layer, and the transition layer adopts epoxy resin and nano aluminum oxide.

4. A method for preparing a corrosion-resistant color-coated steel sheet based on EB curing technology as described in claim 1, 2, or 3, characterized in that, The steps include: 1) applying a primer to the surface of the steel plate; 2) Dry the steel plate coated with primer to form a primer layer; 3) Apply EB curing coating to the primer layer of the dried steel plate; 4) Gradient EB curing is performed on the EB curing coating; the gradient EB curing adopts three-stage energy regulation, with energy of 80-100 keV, 100-120 keV and 120-150 keV respectively, total dose of 60-80 KGy, and irradiation time of 400-800 ms.

5. The method for preparing a corrosion-resistant color-coated steel sheet based on EB curing technology according to claim 4, characterized in that: In step 2), the baking temperature during the drying process is 180℃~240℃.

6. The method for preparing a corrosion-resistant color-coated steel sheet based on EB curing technology according to claim 4, characterized in that: In step 1), the steel plate is passivated before the primer is applied.

7. A method for preparing a corrosion-resistant color-coated steel sheet based on EB curing technology according to claim 4, 5 or 6, characterized in that: Step 2) can be performed on the primer layer by embossing or printing.