Aluminized zinc plate

Abstract

Disclosed in the present invention is an aluminized zinc plate. The aluminized zinc plate comprises a steel plate substrate, wherein aluminum-zinc alloy layers are deposited on the upper and lower surfaces of the steel plate substrate by means of a hot dipping process; the aluminum-zinc alloy layers are coated with chromium-free passivation films; the chromium-free passivation films are coated with chromium-free anti-fingerprint films; and the chromium-free anti-fingerprint films are coated with PE protective films. The aluminized zinc plate has a yield strength of 190-360 MPa, a tensile strength of 270-400 MPa, an elongation of 20-30%, and a hardness of 55-65 HRB. The present application overcomes the defects of aluminized zinc plates in the downstream production line.

Description

Aluminum-zinc plated sheet TECHNICAL FIELD

[0001] The present application relates to the field of household appliances and electronic technology, and in particular to an aluminum-zinc plated sheet. BACKGROUND

[0002] The aluminum-zinc plated product for liquid crystal backboard is a new generation of energy-saving and environment-friendly green product, and is currently mainly used for manufacturing small liquid crystal display and refrigerator backboard. After the aluminum-zinc plated product for liquid crystal backboard replaces the traditional material, on the one hand, the material cost is greatly reduced, and on the other hand, the manufacturing process such as spraying which may cause environmental pollution is reduced. At the same time, the performance indicators such as strength and surface quality of the product are more advantageous than those of the traditional material, so the product is favored by users. However, with the upgrading of materials in the downstream industry and the improvement of user requirements, the users are increasingly unable to accept the defects such as cracking of the zinc layer, black spots and horizontal white lines on the surface of the previous aluminum-zinc plated product for liquid crystal backboard, which seriously affects the user experience. SUMMARY

[0003] In view of the defects in the prior art, the present application provides an aluminum-zinc plated sheet.

[0004] The present application is achieved by the following technical solutions:

[0005] The aluminum-zinc plated sheet comprises a steel plate base body, an aluminum-zinc alloy layer is deposited on the steel plate base body through a hot-dip plating process on the upper and lower surfaces of the steel plate base body, a chromium-free passivation film is coated on the aluminum-zinc alloy layer, a chromium-free anti-fingerprint film is coated on the chromium-free passivation film, and a PE protective film is coated on the chromium-free anti-fingerprint film; the aluminum-zinc alloy layer is a quaternary alloy layer Al-Zn-Fe-Si, the thickness of the quaternary alloy layer is 15-20 microns, the mass fraction of Al is 53%-55%, the mass fraction of Zn is 43%-44%, the mass fraction of Fe is 0.5%, the mass fraction of Si is 1.2%-1.6%, and the surface roughness of the quaternary alloy layer is 0.6-1.2 microns; the yield strength of the aluminum-zinc plated sheet is 190-360 Mpa, the tensile strength is 270-400 Mpa, the elongation rate is 20%-30%, and the hardness is 55-65 HRB.

[0006] Preferably, the steel plate base body is a common carbon structural steel, the carbon content of which is 0.03%-0.08%, the silicon content is 0.03%-0.05%, the manganese content is 0.2%-0.3%, the sulfur content is 0.02%-0.03%, and the phosphorus content is 0.02%-0.03%.

[0007] Preferably, the steel plate substrate needs to be pretreated before the hot-dip plating process, first removing the residual oil and residual iron on the surface of the steel plate substrate through degreasing cleaning, and then entering the continuous annealing furnace, using hydrogen and nitrogen as the medium in the annealing furnace, nitrogen as the protective gas and hydrogen as the reducing gas, and the iron oxide on the surface of the steel plate substrate is reduced to iron by hydrogen.

[0008] Preferably, the pretreated steel plate substrate enters a high-temperature plating tank at 600 DEG C, and a dense quaternary crystal is plated on the surface of the steel plate substrate, which is composed of aluminum, zinc, iron and silicon, and then the steel plate substrate is rapidly cooled to 40-60 DEG C, and the surface roughness of the aluminum-zinc alloy layer is controlled to 0.6-1.2 microns through the finishing process and the straightening process.

[0009] Preferably, the thickness of the chromium-free passivation film is 0.3-0.6 microns, the weight of the chromium-free passivation film is 5-10 mg / m 2 ; the chromium-free passivation film is coated on the aluminum-zinc alloy layer by the roll coating method of the roll coater using the chromium-free passivation agent, and is baked and solidified in the oven at 200-300 DEG C to form a dense chromium-free passivation film, and the composition of the chromium-free passivation agent includes zinc oxide, aluminum oxide and magnesium oxide.

[0010] Preferably, the film thickness of the chromium-free anti-fingerprint film is 1.0-2.0 microns; the chromium-free anti-fingerprint film is coated on the chromium-free passivation film by the roll coating method of the roll coater using the chromium-free anti-fingerprint treatment liquid, and is baked and solidified in the oven at 400-500 DEG C to form a dense chromium-free anti-fingerprint film, and the chromium-free anti-fingerprint treatment liquid is prepared from lithium silicate, glycidyl ether oxypropyltrimethoxysilane and 1,2-bis-(trimethoxy)ethane, wherein the mass fraction of lithium silicate is 9%-13%, the mass fraction of glycidyl ether oxypropyltrimethoxysilane is 4%-7%, and the mass fraction of 1,2-bis-(trimethoxy)ethane is 3%-6%.

[0011] The beneficial effects of the present application are that the present application solves the defects of the plated layer cracking, black spots, transverse white lines and the like in the profiling and bending process of the aluminum-zinc plated product for liquid crystal backplane, and improves the product quality and user experience of the downstream production line. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual proportion.

[0013] Figure 1 is a sectional view of the present application of the aluminum-zinc plated sheet.

[0014] Fig. 2 is a photograph of the aluminized zinc plate with color difference, black spots and black spots.

[0015] Fig. 3 is a photograph of the aluminized zinc plate with scratches and white strip defects.

[0016] Fig. 4 is a photograph of the aluminized zinc plate with excellent surface quality.

[0017] In the drawings, 1 is a steel plate substrate, 2 is an aluminum-zinc alloy layer, 3 is a chromium-free passivation film, 4 is a chromium-free anti-fingerprint film, and 5 is a PE protective film. DETAILED DESCRIPTION

[0018] To make the above-mentioned objects, features and advantages of the present application more apparent and comprehensible, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, a large number of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0020] The present application will be described in detail below with reference to the accompanying drawings: an aluminized zinc plate according to the present application comprises a steel plate substrate, an aluminum-zinc alloy layer deposited on the upper and lower surfaces of the steel plate substrate by hot-dip plating process, a chromium-free passivation film coated on the aluminum-zinc alloy layer, a chromium-free anti-fingerprint film coated on the chromium-free passivation film, and a PE protective film coated on the chromium-free anti-fingerprint film; the aluminum-zinc alloy layer is a quaternary alloy layer Al-Zn-Fe-Si with a thickness of 15-20 microns, wherein the mass fraction of Al is 53%-55%, the mass fraction of Zn is 43%-44%, the mass fraction of Fe is 0.5%, and the mass fraction of Si is 1.2%-1.6%, and the surface roughness of the quaternary alloy layer is 0.6-1.2 microns; the yield strength of the aluminized zinc plate is 190-360 MPa, the tensile strength is 270-400 MPa, the elongation is 20%-30%, and the hardness is 55-65 HRB.

[0021] The steel plate substrate is a common carbon structural steel with a carbon content of 0.03%-0.08%, a silicon content of 0.03%-0.05%, a manganese content of 0.2%-0.3%, a sulfur content of 0.02%-0.03%, and a phosphorus content of 0.02%-0.03%.

[0022] The steel plate substrate needs to be pretreated before the hot dip process, first remove the residual oil and residual iron on the surface of the steel plate substrate by degreasing cleaning, and then enter the continuous annealing furnace. Hydrogen and nitrogen are used as the medium in the annealing furnace, nitrogen is a protective gas, and hydrogen is a reducing gas. The iron oxide on the surface of the steel plate substrate can be reduced to iron by hydrogen.

[0023] The pretreated steel plate substrate enters a high-temperature plating tank at 600°C to form a dense quaternary crystal on the surface of the steel plate substrate, which is composed of aluminum, zinc, iron and silicon. Then the steel plate substrate is rapidly cooled to 40-60°C, and the surface roughness of the aluminum-zinc alloy layer is controlled to 0.6-1.2 microns through the finishing process and the straightening process. The surface roughness of the aluminum-zinc alloy layer is controlled in this range to ensure the adhesion of the subsequent chromium-free passivation film. When the surface roughness is less than 0.6 microns, the surface friction coefficient is very small, and the adhesion of the chromium-free passivation film will be poor. When the surface roughness is higher than 1.2 microns, it will affect the appearance of the aluminum-zinc plated sheet.

[0024] The thickness of the chromium-free passivation film is 0.3-0.6 microns, and the weight of the chromium-free passivation film is 5-10 mg / m 2 When the film thickness of the chromium-free passivation film is greater than 0.6 microns and the weight is greater than 10 mg / m 2 When the film thickness of the chromium-free passivation film is less than 0.3 microns and the weight is less than 5 mg / m 2 The corrosion resistance of the aluminum-zinc plated sheet will be poor, greatly shortening its service life; the chromium-free passivation film is coated on the aluminum-zinc alloy layer by roll coating with a chromium-free passivation agent through a roll coater, and is cured in an oven at 200-300°C to form a dense chromium-free passivation film. Chromium-free passivation agent is a chemical substance used for metal surface treatment, mainly used to prevent metal oxidation and corrosion. Its main components include zinc oxide, aluminum oxide and magnesium oxide, which can effectively form a protective film on the metal surface to prevent oxidation and corrosion.

[0025] The film thickness of the chromium-free fingerprint-resistant film is 1.0-2.0 microns. It is found through experiments that when the film thickness is less than 1.0 microns, black spots and other defects are prone to occur in the downstream press bending process. When the film thickness is higher than 2.0 microns, the aluminum-zinc plated product is prone to color difference defects caused by fingerprint-resistant adhesion. When the film thickness is within the above range, the fingerprint-resistant coating has good fingerprint resistance, corrosion resistance and high temperature resistance when the stripe is higher than 100 degrees Celsius. The chromium-free fingerprint-resistant film is coated on the chromium-free passivation film by a roll coater using a chromium-free fingerprint-resistant treatment solution, and is baked and solidified in a 400-500 degree Celsius oven to form a dense chromium-free fingerprint-resistant film. The chromium-free fingerprint-resistant treatment solution is prepared by using lithium silicate, glycidyl ether oxypropyltrimethoxysilane and 1,2-bis-(trimethoxy)ethane as raw materials, adopting sol-gel method and organic-inorganic hybrid technology to prepare a chromium-free fingerprint-resistant treatment solution with excellent high temperature baking performance, and using the treatment solution as the basis to prepare a chromium-free fingerprint-resistant coating. The mass percentage of lithium silicate in the chromium-free fingerprint-resistant treatment solution is 9%-13%, the mass percentage of glycidyl ether oxypropyltrimethoxysilane is 4%-7%, and the mass percentage of 1,2-bis-(trimethoxy)ethane is 3%-6%.

[0026] Three experiments were conducted on the ratio of the three raw materials of the chromium-free fingerprint-resistant treatment solution.

[0027] In the first experiment, the mass percentage of the three raw materials was higher than the above-mentioned range value. During use in the downstream industry, the aluminum-zinc plated sheet had color difference, black spot and black spot defects, as shown in the physical diagram of FIG. 2.

[0028] In the second experiment, the mass percentage of the three raw materials was lower than the above-mentioned range value. During use in the downstream industry, the aluminum-zinc plated sheet had scratches and white line defects, as shown in the physical diagram of FIG. 3.

[0029] In the third experiment, the mass percentage of the three raw materials was controlled within the above range value. During use in the downstream industry, there was no abnormality, and the surface quality was excellent, as shown in the physical diagram of FIG. 4.

[0030] The product is a kind of alloy steel plate, which is deposited with aluminum-zinc alloy coating on steel plate substrate by hot-dip plating process. It takes low-carbon steel cold hard coil as raw material, removes residual oil and residual iron on the surface of steel plate substrate after pretreatment degreasing cleaning, then enters the continuous annealing furnace, hydrogen and nitrogen are used as medium in the annealing furnace, nitrogen is protective gas, and hydrogen is reducing gas, iron on the surface of steel plate substrate is reduced to iron by hydrogen, then enters the high-temperature plating tank of 600 DEG C, a layer of dense quaternary crystal is plated on the surface of steel plate substrate, the whole structure is composed of aluminum-iron-silicon-zinc, then the steel plate substrate is rapidly cooled by combining air cooling and water cooling, after the steel plate substrate is cooled to 40-60 DEG C, the surface roughness of quaternary alloy layer is controlled to 0.6-1.2 microns through finishing process and straightening process, then enters the post-treatment stage, a layer of chromium-free passivation film and chromium-free fingerprint-resistant film are coated on the surface by using roll coater, finally enters the cold film covering stage, a layer of PE protective film is attached on the surface by film covering machine, and the product is finally obtained.

[0031] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application.

Claims

1. A zinc-aluminum plated sheet comprising a steel sheet base body (1), characterized in that: The upper and lower surfaces of the steel plate substrate (1) are deposited with an aluminum-zinc alloy layer (2) by a hot-dip plating process, the aluminum-zinc alloy layer (2) is coated with a chromium-free passivation film (3), the chromium-free passivation film (3) is coated with a chromium-free anti-fingerprint film (4), and the chromium-free anti-fingerprint film (4) is covered with a PE protective film (5); the aluminum-zinc alloy layer (2) is a quaternary alloy layer Al-Zn-Fe-Si, the thickness of the quaternary alloy layer is 15-20 microns, the mass fraction of Al is 53%-55%, the mass fraction of Zn is 43%-44%, the mass fraction of Fe is 0.5%, and the mass fraction of Si is 1.2%-1.6%, and the surface roughness of the quaternary alloy layer is 0.6-1.2 microns; the yield strength of the aluminum-zinc plated sheet is 190-360 MPa, the tensile strength is 270-400 MPa, the elongation is 20%-30%, and the hardness is 55-65 HRB.

2. The aluminum-zinc plated sheet according to claim 1, characterized in that: The steel plate substrate (1) is a common carbon structural steel, the carbon content is 0.03%-0.08%, the silicon content is 0.03%-0.05%, the manganese content is 0.2%-0.3%, the sulfur content is 0.02%-0.03%, and the phosphorus content is 0.02%-0.03%.

3. The galvalume sheet as claimed in claim 1, wherein: The steel plate substrate (1) needs to be pretreated before the hot-dip plating process, first, the residual oil and residual iron on the surface of the steel plate substrate (1) are removed by degreasing and cleaning, and then the steel plate substrate (1) enters a continuous annealing furnace, hydrogen and nitrogen are used as the medium in the annealing furnace, nitrogen is a protective gas, and hydrogen is a reducing gas, and the iron oxide on the surface of the steel plate substrate (1) is reduced to iron by hydrogen.

4. The galvalume sheet as claimed in claim 3, wherein: The pretreated steel plate substrate (1) enters a high-temperature plating tank at 600°C, a dense quaternary crystal layer is plated on the surface of the steel plate substrate (1), the quaternary crystal layer is composed of aluminum, zinc, iron and silicon, and then the steel plate substrate (1) is rapidly cooled to 40-60°C, the surface roughness of the aluminum-zinc alloy layer (2) is controlled to be 0.6-1.2 microns through a finishing process and a tension leveling process.

5. The galvalume sheet as claimed in claim 1, wherein: The thickness of the chromium-free passivation film (3) is 0.3-0.6 microns, and the weight of the chromium-free passivation film (3) is 5-10 mg / m 2 The chromium-free passivation film (3) is coated onto the aluminum-zinc alloy layer (2) by means of a roll coater using a chromium-free passivation agent, and is baked and cured in an oven at 200-300 DEG C to form a dense chromium-free passivation film (3). The composition of the chromium-free passivation agent includes zinc oxide, aluminum oxide and magnesium oxide.

6. The aluminum-zinc plated sheet according to claim 1, characterized in that: The film thickness of the chromium-free anti-fingerprint film (4) is 1.0-2.0 microns; the chromium-free anti-fingerprint film (4) is coated on the chromium-free passivation film (3) by a roll coating method of a roll coater, and is baked and solidified in an oven at 400-500°C to form a dense chromium-free anti-fingerprint film (4), the chromium-free anti-fingerprint treatment liquid is prepared from lithium silicate, glycidyl ether oxypropyltrimethoxysilane and 1,2-bis-(trimethoxy)ethane, the mass fraction of lithium silicate is 9%-13%, the mass fraction of glycidyl ether oxypropyltrimethoxysilane is 4%-7%, and the mass fraction of 1,2-bis-(trimethoxy)ethane is 3%-6%.

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