A process for producing color aluminum sheets

Abstract

This application relates to the field of color aluminum plate processing technology, and specifically discloses a color aluminum plate production process, including the following steps: (1) uncoiling-riveting-cutting to obtain aluminum raw material; (2) looping-pretreatment to obtain aluminum substrate; (3) scratch repair, spraying powder particles of the same material as the aluminum raw material onto the scratched area of ​​the aluminum substrate surface, and obtaining pretreated aluminum substrate after surface grinding; (4) chemical coating to obtain aluminum substrate with a chemical conversion film; (5) back coating-top coating to obtain semi-finished product; (6) varnishing-inspection-rewinding to obtain color aluminum plate. The color aluminum plate production process of this application can improve the scratch treatment capability of the color aluminum plate production process, thereby improving the overall quality of the color aluminum plate.

Description

Technical Field

[0001] This application relates to the field of color aluminum sheet processing technology, and more specifically, it relates to a color aluminum sheet production process. Background Technology

[0002] Aluminum sheets are rectangular plates made by rolling aluminum ingots. They are classified into pure aluminum sheets, alloy aluminum sheets, thin aluminum sheets, and color-coated aluminum sheets, among others. Color-coated aluminum sheets are the most widely used type of aluminum sheet. Due to their good mechanical properties, light weight, high strength, and quick and convenient installation, color-coated aluminum sheets are most widely used in the construction of prefabricated houses and protective walls.

[0003] For example, Chinese invention patent application CN110976253A discloses a process for producing color-coated aluminum sheets, including the following steps: ① Uncoiling: The aluminum coil is opened by rotating an uncoiler, and the strip tension and centering are established during the operation; ② Sewing: The opened aluminum coil is quickly sewn together mechanically; ③ Pre-coating treatment of aluminum coil: The sewn aluminum coil is degreased, and the surface of the degreased aluminum coil is cleaned and dried; ④ Roll coating: The aluminum coil in step ③ is coated with a film using a continuous two-coat, two-bake process on both sides; ⑤ Baking, curing and cooling: The liquid coating on the surface of the aluminum coil is cured by baking, and the temperature of the oven is controlled to cool the coating after curing, resulting in a color-coated aluminum sheet; ⑥ Rewinding: The color-coated aluminum sheet cooled in step ⑤ is rewound using a rewinder; ⑦ Packaging and warehousing: Finally, the color-coated aluminum sheet is unloaded after rewinding, cut, inspected, packaged and stored.

[0004] Regarding the aforementioned technologies, the inventors believe that the aluminum substrate obtained before coating will inevitably have scratches on its surface after a series of pretreatment operations. Using scratched aluminum substrates for coating will easily result in poor adhesion of the coating film on the produced color aluminum plate or even quality defects such as missed coating. Therefore, there is an urgent need to propose a solution to solve the above-mentioned technical problems. Summary of the Invention

[0005] In order to improve the ability to handle scratches in the production process of color aluminum sheets and to improve the overall quality of color aluminum sheets, this application provides a color aluminum sheet production process.

[0006] This application provides a color-coated aluminum sheet manufacturing process, which adopts the following technical solution: A process for producing color-coated aluminum sheets includes the following steps: (1) Uncoiling, riveting, and cutting are performed to obtain aluminum raw materials; (2) Loose-loop pretreatment: The aluminum raw material is loose-loop processed and kept in an arc-shaped loop. Then, it is pretreated with degreasing agent and pickling agent in sequence. After washing and drying, the aluminum substrate is obtained. (3) Scratch repair: Spray powder particles of the same material as the aluminum raw material onto the scratched area of ​​the aluminum substrate surface, and obtain the pre-treated aluminum substrate after surface grinding. (4) Chemical coating: Spray the surface of the pretreated aluminum substrate with chromate treatment solution, dry it to form a film, and obtain an aluminum substrate with a chemical conversion film. (5) Base coating - top coating: Polyurethane coating is used to apply a base coating to the aluminum substrate with a chemical conversion film. After baking, cooling and drying, epoxy coating is applied for the back coating. After baking, cooling and drying, polyester coating is applied for the top coating to obtain a semi-finished product. (6) Coating-inspection-winding: Coating the surface of the semi-finished product with a coating, baking, cooling and drying, and after passing the inspection, the product can be wound up to obtain the color aluminum plate.

[0007] By adopting the above technical solution, before coating the aluminum substrate, powder particles of the same material as the aluminum raw material are sprayed onto the scratched area of ​​the aluminum substrate surface. The strong spraying action causes the powder particles of the same material as the aluminum raw material to be deposited in the scratch gaps and form an accumulation. Then, through a smoothing process, the original scratched area of ​​the aluminum substrate is kept flat, which can bring a strong scratch repair effect, ensure the integrity and stability of the subsequent coating film, and have excellent adhesion, which is conducive to obtaining a color aluminum plate with excellent surface quality.

[0008] Preferably, in step (3), the spraying range is 0.5-1 mm outward from the scratch.

[0009] By adopting the above technical solution and selecting the above spray range, the powder particles of the same material as the aluminum raw material can form a relatively complete coverage of the scratches during the spraying process. Under the premise of ensuring a better repair effect, it can save the use of powder particles of the same material as the aluminum raw material, and can improve the efficiency of subsequent surface grinding to a certain extent. In this way, the entire color aluminum plate production process is smoother and more stable, and high-quality color aluminum plates can be obtained.

[0010] Preferably, in step (3), the particle size of the powder particles of the same material as the aluminum raw material is 30-50μm.

[0011] By adopting the above technical solution and selecting the above particle size, on the one hand, it can strongly grip the aluminum substrate at the scratch under the spraying action, and on the other hand, it can fill the scratch more completely and form a dense accumulation, resulting in a better overall repair effect. This makes the surface coating of the produced color aluminum plate more uniform and complete, and has excellent adhesion, thus obtaining a high-quality color aluminum plate.

[0012] Preferably, in step (3), the powder particles of the same material as the aluminum raw material are also doped with aluminum powder, copper powder, titanium powder and silicon carbide powder, and after the spraying is completed, the spraying range area is laser clad, cooled and then the surface is ground flat.

[0013] By adopting the above technical solution, the incorporation of aluminum powder, copper powder, titanium powder and silicon carbide powder, after laser cladding, can combine with powder particles of the same material as the aluminum raw material to form a relatively stable structure. This structure can not only completely fill the scratches, but also is not easy to loosen or fall off during subsequent coating processes, thereby ensuring the integrity and stability of the surface structure of the final color aluminum plate, and greatly improving the quality of the color aluminum plate.

[0014] Preferably, the total amount of aluminum powder, copper powder, titanium powder and silicon carbide powder is 8%-15% of the powder particles of the same material as the aluminum raw material, and the weight ratio of aluminum powder, copper powder, titanium powder and silicon carbide powder is (30-40):(40-50):(8-12):1.

[0015] By adopting the above technical solution, the proportions of aluminum powder, copper powder, titanium powder, and silicon carbide powder used, as well as the combination of these powders, can result in a denser structure after laser cladding. This structure becomes smoother after surface grinding and exhibits a tighter interface with the aluminum substrate at the scratches. Especially at the junction of the aluminum substrate and the structure, the subsequent coating film is more uniform and complete, with excellent adhesion. Thus, a color aluminum plate with superior overall quality can be obtained.

[0016] Preferably, the weight ratio of the aluminum powder, copper powder, titanium powder and silicon carbide powder is 35:45:10:1.

[0017] By adopting the above technical solution and combining aluminum powder, copper powder, titanium powder and silicon carbide powder in the above proportions, the actual application shows excellent results, with better scratch repair effect and higher surface quality of the produced color aluminum plate.

[0018] Preferably, in step (3), during the laser cladding operation, the laser power is 1.2-1.6kW, the scanning speed is 130-160mm / min, and the defocusing amount is 45-55mm.

[0019] By adopting the above technical solution and controlling the parameters during the laser cladding process, the resulting structure can have strong continuity and high integrity, and the surface is less prone to deep depressions. It can also form a tighter bond with the aluminum substrate, thereby bringing better scratch repair effect.

[0020] Preferably, in step (4), the drying temperature is 50-60℃, the drying time is 10-30min, and the thickness of the chemical conversion film on the aluminum substrate is 1.5-4μm.

[0021] By adopting the above technical solution and controlling the temperature and time, the chromate treatment solution can form a continuous and complete chemical conversion film on the scratches of the original aluminum substrate after repair. The chemical conversion film of the above thickness can not only ensure stable coverage of the scratch repair area, but also provide a good adhesion base for subsequent coating materials, which is conducive to ensuring the excellent quality of the final color aluminum plate.

[0022] Preferably, in step (5), after the base coat is dried, the film thickness is 5-7 μm; after the back coat is dried, the film thickness is 5-7 μm; and after the top coat is dried, the film thickness is 10-14 μm.

[0023] By adopting the above technical solution, the selection of the above coating thickness can be suitable for the needs of rapid drying, and the film is relatively uniform after formation, showing strong adhesion, so that the obtained colored aluminum plate has a high appearance quality.

[0024] In summary, this application has the following beneficial effects: 1. This application repairs scratches by spraying powder particles of the same material as the aluminum material onto the scratched area of ​​the aluminum substrate before coating the aluminum substrate, and then grinding it smooth. This ensures the integrity and stability of the subsequent coating film and has excellent adhesion, which is beneficial to obtaining a color aluminum plate with excellent surface quality. 2. This application involves doping aluminum powder, copper powder, titanium powder and silicon carbide powder into powder particles of the same material as aluminum raw material, and then performing laser cladding after spraying. The resulting structure fills the scratches and provides a repair function. The bond between the structure and the aluminum substrate is more stable and less prone to loosening or falling off during subsequent coating processes, thereby enabling the obtained color aluminum plate to have better surface quality. Detailed Implementation

[0025] The present application will be further described in detail below with reference to the embodiments.

[0026] Unless otherwise specified, all raw materials used in the preparation examples and embodiments of this application are commercially available. The degreasing agent was purchased from Anmei PM4007 aluminum alloy degreasing agent; The pickling agent was purchased from Henkel Deoxidine SC 56CF aluminum alloy pickling agent from Germany; The chromate treatment solution is an aqueous solution of chromate with a concentration of 1000 μg / mL; The polyester coating is Evonik L952 polyester coating; The epoxy coating is SIGMACOVER 380 high-solids epoxy paint; The polyurethane coating is PL-D220 type polyurethane paint; The topcoat is TY-6100. Example

[0027] Example 1 A process for producing color-coated aluminum sheets includes the following steps: (1) Uncoiling, riveting, and cutting are performed to obtain aluminum raw materials; (2) Loose-loop pretreatment: The aluminum raw material is loose-loop processed and kept in an arc-shaped loop. Then, it is pretreated with degreasing agent and pickling agent in sequence. After washing and drying, the aluminum substrate is obtained. (3) Scratch repair: Spray powder particles of the same material as the aluminum raw material onto the scratched area of ​​the aluminum substrate surface, and obtain the pre-treated aluminum substrate after surface grinding. (4) Chemical coating: Spray the surface of the pretreated aluminum substrate with chromate treatment solution, dry it to form a film, and obtain an aluminum substrate with a chemical conversion film. (5) Base coating - top coating: Polyurethane coating is used to apply a base coating to the aluminum substrate with a chemical conversion film. After baking, cooling and drying, epoxy coating is applied for the back coating. After baking, cooling and drying, polyester coating is applied for the top coating to obtain a semi-finished product. (6) Coating-inspection-winding: Coating the surface of the semi-finished product with a coating, baking, cooling and drying, the dry film thickness of the coating is 20μm. After passing the inspection, the product can be wound up to obtain the color aluminum plate.

[0028] Note: In step (3), the spraying range is the area extending outward from the scratch by 0.75 mm; in step (3), the particle size of the powder particles of the same material as the aluminum raw material is 40 μm; in step (4), the drying temperature is 55℃, the drying time is 20 min, and the thickness of the chemical conversion film on the aluminum substrate is 2.75 μm; in step (5), after the base coating is dried, the film thickness is 6 μm; after the back coating is dried, the film thickness is 6 μm; after the top coating is dried, the film thickness is 12 μm.

[0029] Example 2 A process for producing colored aluminum sheets differs from Example 1 in that, in step (3), the spraying range is 0.5 mm outward from the scratch.

[0030] Example 3 A color aluminum plate production process differs from Example 1 in that, in step (3), the spraying range is 1 mm outward from the scratch.

[0031] Example 4 A color aluminum plate production process differs from Example 1 in that, in step (4), the drying temperature is 50°C, the drying time is 30 min, and the thickness of the chemical conversion film on the aluminum substrate is 4 μm.

[0032] Example 5 A color aluminum plate production process differs from Example 1 in that, in step (4), the drying temperature is 60°C, the drying time is 10 min, and the thickness of the chemical conversion film on the aluminum substrate is 1.5 μm.

[0033] Example 6 A process for producing colored aluminum sheets differs from Example 1 in that, in step (5), the thickness of the base coating after drying is 5 μm; the thickness of the back coating after drying is 5 μm; and the thickness of the top coating after drying is 10 μm.

[0034] Example 7 A process for producing colored aluminum sheets differs from Example 1 in that, in step (5), the thickness of the base coating after drying is 7 μm; the thickness of the back coating after drying is 7 μm; and the thickness of the top coating after drying is 14 μm.

[0035] Example 8 A color aluminum plate production process differs from Example 1 in that, in step (3), the powder particles of the same material as the aluminum raw material are also mixed with aluminum powder, copper powder, titanium powder and silicon carbide powder, and after spraying, the sprayed area is laser clad, cooled and then the surface is ground flat. In the above laser cladding operation, the laser power is 1.4kW, the scanning speed is 145mm / min, and the defocusing amount is 50mm; the total amount of aluminum powder, copper powder, titanium powder and silicon carbide powder is 11.5% of the powder particles of the same material as the aluminum raw material, and the weight ratio of aluminum powder, copper powder, titanium powder and silicon carbide powder is 35:45:10:1.

[0036] Example 9 A process for producing colored aluminum sheets differs from Example 8 in that the total amount of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 8% of the powder particles of the same material as the aluminum raw material.

[0037] Example 10 A process for producing colored aluminum sheets differs from Example 8 in that the total amount of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 15% of the powder particles of the same material as the aluminum raw material.

[0038] Example 11 A process for producing colored aluminum sheets differs from Example 8 in that the weight ratio of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 30:40:8:1.

[0039] Example 12 A process for producing colored aluminum sheets differs from Example 8 in that the weight ratio of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 40:50:12:1.

[0040] Example 13 A process for producing colored aluminum sheets differs from Example 8 in that, during the laser cladding operation, the laser power is 1.2kW, the scanning speed is 130mm / min, and the defocusing amount is 45mm.

[0041] Example 14 A process for producing colored aluminum sheets differs from Example 8 in that, during the laser cladding operation, the laser power is 1.6kW, the scanning speed is 160mm / min, and the defocusing amount is 55mm.

[0042] Example 15 A process for producing colored aluminum sheets differs from Example 8 in that the weight ratio of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 28:38:6:1.

[0043] Example 16 A process for producing colored aluminum sheets differs from Example 8 in that the weight ratio of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 42:52:14:1.

[0044] Example 17 A process for producing colored aluminum sheets differs from Example 8 in that the powder particles of the same material as the aluminum raw material are not mixed with copper powder.

[0045] Example 18 A process for producing colored aluminum sheets differs from Example 8 in that the powder particles of the same material as the aluminum raw material are not doped with titanium powder.

[0046] Comparative Example Comparative Example 1 A process for producing colored aluminum sheets, which differs from Example 1 in that it does not include the production operation in step (3).

[0047] Performance testing test samples: 1060 aluminum alloy coils were used and processed using the color aluminum plate production process in Examples 1-18 and Comparative Example 1. After obtaining the aluminum substrate in step (2), four scratches were artificially made on the surface of the aluminum substrate. The scratches were 50 mm long, 0.1 mm deep, and 0.3 mm wide. The location of the scratches was recorded in photographs. Then, subsequent operations were performed to obtain 19 kinds of color aluminum plates.

[0048] Test methods: (1) Missing coating: For 19 types of colored aluminum panels, the positions of the scratches recorded on the original surface were observed to see if there was any missing coating. The corresponding results were recorded in Table 1 in comparison with Examples 1-18 and Comparative Example 1; (2) Adhesion: For 19 types of colored aluminum panels, the adhesion was tested according to the content of standard GBT22412-2016 "Aluminum Composite Panels for Ordinary Decoration". The circular rolling method was adopted. The test was carried out according to the provisions of GB / T 1720. The circular rolling line path was carried out along the scratch path. The integrity of the paint film on the surface of each colored aluminum panel was rated. Grade 1 was the best and Grade 7 was the worst; (3) Impact resistance test: For 19 types of colored aluminum panels, the impact resistance test was carried out according to the content of standard GBT22412-2016 "Aluminum Composite Panels for Ordinary Decoration". The back of the colored aluminum panel was impacted, and the maximum impact height at which the coating at the scratch of each sample did not crack or fall off was measured after the impact.

[0049] Table 1 Test results of Examples 1-18 and Comparative Example 1 As can be seen from Example 1 and Comparative Example 1, and Table 1, this application repairs scratches by spraying powder particles of the same material as the aluminum material onto the scratched area of ​​the aluminum substrate before coating the aluminum substrate, and then grinding it smooth. This helps to ensure the integrity and stability of the subsequent coating film, prevents missed coating, and results in a better surface quality of the colored aluminum plate. The measured adhesion and impact resistance are both high, which can effectively overcome the defects caused by scratches and has significant application effects.

[0050] Combining Examples 1 and 2-3 with Table 1, it can be seen that in step (3), the spraying range is 0.5-1mm outward from the scratch, which can ensure the excellent and stable repair effect brought about by step (3), and thus ensure the high quality and stable quality of the colored aluminum plate.

[0051] Combining Examples 1 and 4-5 with Table 1, it can be seen that in step (4), the drying temperature is 50-60℃, the drying time is 10-30min, and the thickness of the chemical conversion film on the aluminum substrate is 1.5-4μm. Under the premise of ensuring stable coverage of the scratch repair area, it can also provide a good adhesion base for the subsequent coating material, which is conducive to ensuring that a high-quality and stable color aluminum plate is obtained.

[0052] Combining Examples 1 and 6-7 with Table 1, it can be seen that in step (5), after the base coating is dried, the film thickness is 5-7 μm; after the back coating is dried, the film thickness is 5-7 μm; and after the top coating is dried, the film thickness is 10-14 μm, all of which enable the obtained colored aluminum plate to have high appearance quality.

[0053] Combining Examples 1 and 8-12 with Table 1, it can be seen that the powder particles of the same material as the aluminum raw material are also doped with aluminum powder, copper powder, titanium powder, and silicon carbide powder. These are then clad into a structure by laser cladding, which completely fills the scratches, improving the scratch repair effect and significantly enhancing the quality of the color-coated aluminum sheet. The adhesion and impact resistance measured in the tests are also significantly improved. Specifically, when the total amount of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 8%-15% of the powder particles of the same material as the aluminum raw material, and the weight ratio of aluminum powder, copper powder, titanium powder, and silicon carbide powder is (30-40):(40-50):(8-12):1, a color-coated aluminum sheet of excellent and stable quality can be obtained. When the weight ratio of aluminum powder, copper powder, titanium powder, and silicon carbide powder is 35:45:10:1, the quality of the color-coated aluminum sheet is even better. Furthermore, referring to Examples 15-16 and Table 1, it can be seen that when the weight ratio of aluminum powder, copper powder, titanium powder, and silicon carbide is lower or higher than the above range, the measured impact resistance is significantly reduced. Furthermore, referring to Examples 17-18 and Table 1, it can be seen that when the powder particles of the same material as the aluminum raw material do not contain copper powder or titanium powder, the measured impact resistance is also significantly reduced. Therefore, it can be seen that using aluminum powder, copper powder, titanium powder, and silicon carbide in a specific weight ratio as additives, combined with laser cladding, can produce high-quality colored aluminum sheets.

[0054] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A process for producing color-coated aluminum sheets, characterized in that, Includes the following steps: (1) Uncoiling, riveting, and cutting to obtain aluminum raw material; (2) Loose-loop pretreatment: The aluminum raw material is loose-loop processed and kept in an arc shape. Then, it is pretreated with degreasing agent and pickling agent in sequence. After washing and drying, the aluminum substrate is obtained. (3) Scratch repair: Spray powder particles of the same material as the aluminum raw material into the area of ​​the scratch on the surface of the aluminum substrate, and obtain the pre-treated aluminum substrate after the surface is ground smooth. (4) Chemical coating: Spray the surface of the pretreated aluminum substrate with chromate treatment solution, dry it to form a film, and obtain an aluminum substrate with a chemical conversion film. (5) Base coating - top coating: Polyurethane coating is used to apply a base coating to the aluminum substrate with a chemical conversion film. After baking, cooling and drying, epoxy coating is applied to the back coating. After baking, cooling and drying, polyester coating is applied to the top coating to obtain a semi-finished product. (6) Coating-inspection-winding: Coating the surface of the semi-finished product with a varnish, baking, cooling and drying, and after passing the inspection, the product can be wound up to obtain the color aluminum plate; In step (3), the powder particles of the same material as the aluminum raw material are also mixed with aluminum powder, copper powder, titanium powder and silicon carbide powder. After the spraying is completed, the spraying area is laser clad and then the surface is ground after cooling. The total amount of aluminum powder, copper powder, titanium powder and silicon carbide powder is 8%-15% of the powder particles of the same material as the aluminum raw material, and the weight ratio of aluminum powder, copper powder, titanium powder and silicon carbide powder is (30-40): (40-50): (8-12):1; In step (3), during the laser cladding operation, the laser power is 1.2-1.6kW, the scanning speed is 130-160mm / min, and the defocusing amount is 45-55mm.

2. The color aluminum sheet production process according to claim 1, characterized in that: In step (3), the spraying range is the area extending outward from the scratch by 0.5-1mm.

3. The color aluminum sheet production process according to claim 1, characterized in that: In step (3), the particle size of the powder particles of the same material as the aluminum raw material is 30-50μm.

4. The color aluminum sheet production process according to claim 1, characterized in that: The weight ratio of the aluminum powder, copper powder, titanium powder and silicon carbide powder is 35:45:10:

1.

5. The color aluminum sheet production process according to claim 1, characterized in that: In step (4), the drying temperature is 50-60℃, the drying time is 10-30min, and the thickness of the chemical conversion film on the aluminum substrate is 1.5-4μm.

6. The color aluminum sheet production process according to claim 1, characterized in that: In step (5), after the primer is dried, the film thickness is 5-7 μm; after the back coat is dried, the film thickness is 5-7 μm; and after the top coat is dried, the film thickness is 10-14 μm.

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