A method for preparing tin-plated steel sheet

Abstract

This application relates to the fields of energy conservation, environmental protection, and tinplate production technology, and particularly to a method for preparing tinplate. The method includes: water quenching an annealed steel coil, controlling the chloride ion content and conductivity of the solution used in the water quenching process; performing staged cleaning on the water-quenched annealed steel coil, followed by tin plating to obtain a tinplate; using a flux to soften the tinplate, setting the softening temperature according to the thickness of the tinplate; passivating the softened tinplate, followed by oiling, to obtain the tinplate product. This application solves the technical problem of poor corrosion resistance in existing tinplate.

Description

Technical Field

[0001] This application relates to the fields of energy conservation, environmental protection, and tinplate production technology, and in particular to a method for preparing tinplate. Background Technology

[0002] Tinplate (also known as tinplate) refers to cold-rolled thin steel sheets coated with a very thin layer of metallic tin on both sides. It has good sealing, preservation and light protection properties. Its strong oxidation resistance, high strength and good formability determine its wide application in the packaging container industry. It is the world's most widely used metal packaging sheet and is widely used in the packaging of food, medicine, daily necessities and industrial products.

[0003] Currently, the production of tin-plated sheets widely adopts the MSA (methyl sulfonic acid) electroplating process, which features high efficiency, environmentally friendly and non-toxic plating solutions. In order to meet the food safety laws and regulations for food contact materials, the purity of tin ingots used in tin plating is required to be above 99.9%.

[0004] Due to the high cost of tin, downstream customers, considering cost and other economic factors, have gradually reduced the thickness of the tin layer on tinplate, using thinner tinplate to process end products. However, due to insufficient corrosion resistance and the impact of porosity on the tinplate, low-tin-weight tinplate often develops rust spots, severely restricting its practical application. Furthermore, tin is a non-renewable and scarce resource with limited supply. Therefore, from an energy conservation and environmental protection perspective, it is essential to improve the corrosion resistance of low-tin-weight tinplate to prevent rust spots, thereby conserving tin ore resources and promoting energy conservation and environmental protection in this field, reducing the consumption of non-renewable resources. Summary of the Invention

[0005] This application provides a method for preparing tin-plated steel sheets to solve the technical problem of poor corrosion resistance of existing tin-plated steel sheets.

[0006] In a first aspect, this application provides a method for preparing tin-plated steel sheet, the method comprising:

[0007] The annealed steel coil is water quenched, and the chloride ion content and conductivity in the solution used during the water quenching process are controlled.

[0008] The annealed steel coil after water quenching is cleaned in stages and then tin-plated to obtain tin-plated steel sheet.

[0009] The tin-plated steel sheet is softened using a flux, and the softening temperature is set according to the thickness of the tin-plated steel sheet.

[0010] The tin-plated steel sheet after softening and melting is passivated and then coated with oil to obtain the tin-plated steel sheet product.

[0011] Optionally, setting the remelting temperature based on the thickness of the tin-plated steel sheet includes:

[0012] If the thickness of the tin-plated steel sheet is 0.12-0.25mm, then the temperature of the remelting is set as the first temperature;

[0013] If the thickness of the tin-plated steel sheet is 0.26-0.35mm, then the remelting temperature is set as the second temperature;

[0014] If the thickness of the tin-plated steel sheet is 0.36-0.55mm, then the remelting temperature is set as the third temperature.

[0015] Optionally, the first temperature is 250-290°C, and / or the second temperature is 245-285°C, and / or the third temperature is 240-275°C.

[0016] Optionally, the flux is demineralized water.

[0017] Optionally, the chloride ion content is <10 mg / L, and / or the conductivity is <10 μS / cm.

[0018] Optionally, the passivation of the tin-plated steel sheet after remelting, followed by oiling to obtain the tin-plated steel sheet product, includes:

[0019] The tin-plated steel sheet after softening and melting is passivated, and the process parameters of the passivation solution used in the passivation process are controlled. Then, oil is applied to obtain the tin-plated steel sheet product. The process parameters of the passivation solution include: the concentration of the passivation solution, the pH value of the passivation solution, and the temperature of the passivation solution.

[0020] Optionally, the concentration of the passivation solution is 25-31 g / L, the pH value of the passivation solution is 4.1-4.5, and the temperature of the passivation solution is 43-47℃.

[0021] Optionally, the amount of oil used for the coating is 2.0-6.0 mg / m2.

[0022] Optionally, the step of performing staged cleaning on the water-quenched annealed steel coil, followed by tin plating to obtain tin-plated steel sheet, includes:

[0023] The first stage of cleaning was performed on the water-quenched annealed steel coil using a first alkaline solution, followed by a second stage of cleaning using an acid solution.

[0024] The annealed steel coil after the second stage cleaning is tin-plated to obtain tin-plated steel sheet; wherein,

[0025] The concentration of the first alkaline solution is 27-37 g / L, and the temperature of the first alkaline solution is 70-80℃; and or,

[0026] The concentration of the acid solution is 40-50 g / L, and the temperature of the acid solution is 45-55℃.

[0027] Optionally, the step of water quenching the annealed steel coil and controlling the chloride ion content and conductivity in the solution used during the water quenching process includes, prior to:

[0028] The steel coil is then subjected to a third cleaning using a second alkaline solution, followed by annealing to obtain an annealed steel coil; wherein,

[0029] The chloride ion content in the second alkaline solution is ≤20mg / L, and / or the temperature of the second alkaline solution is 70~80℃.

[0030] The technical solutions provided in this application have the following advantages compared with the prior art:

[0031] The method for preparing the tin-plated steel sheet provided in this application, by controlling the process parameters of the steps of water quenching, staged cleaning, tin plating, remelting, passivation and oiling of annealed steel coils, produces a tin-plated steel sheet product with a tin layer thickness of less than 2.8 g / m², which has excellent corrosion resistance and prevents rust spots, thereby saving tin ore resources and promoting energy conservation and environmental protection in this field. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A schematic flowchart illustrating a method for preparing tin-plated steel sheet according to an embodiment of this application;

[0035] Figure 2 A surface image of a tin-plated steel sheet after a salt spray test, provided as Comparative Example 1 of this application;

[0036] Figure 3 This is a surface image of a tin-plated steel sheet after a salt spray test, provided in Embodiment 1 of this application. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0039] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0040] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0041] Firstly, this application provides a method for preparing tin-plated steel sheets; please refer to [link to relevant documentation]. Figure 1 The method includes:

[0042] S1. The annealed steel coil is water-quenched, and the chloride ion content and conductivity in the solution used during the water quenching process are controlled.

[0043] In some embodiments, the chloride ion content is <10 mg / L, and / or the conductivity is <10 μS / cm.

[0044] In this embodiment, the solution is demineralized water. Controlling the chloride ion content in the demineralized water to <10 mg / L and the conductivity to <10 μS / cm has the following positive effects: it improves the purity of the demineralized water, effectively reduces contaminants in the demineralized water, thereby improving cleaning quality and preventing corrosion caused by excessive chloride ions. If the chloride ion content or conductivity in the demineralized water is too high, it can cause corrosion of the annealed coil to a certain extent, incomplete pickling in the tin plating process, affect the corrosion resistance of the final tin-plated steel sheet, and easily cause corrosion and damage to the equipment. Specifically, the chloride ion content can be 9 mg / L, 8 mg / L, or 7 mg / L, and the conductivity can be 9 μS / cm, 8 μS / cm, or 7 μS / cm, etc. This step also includes: checking the water cooling jacket above the water quenching tank for leaks to prevent circulating cooling water from flowing into the demineralized water in the water quenching tank and contaminating it, thus avoiding excessive chloride ion content and conductivity in the demineralized water of the water quenching tank.

[0045] In some embodiments, the process of water quenching the annealed steel coil and controlling the chloride ion content and conductivity of the solution used during the water quenching process includes, prior to:

[0046] The steel coil is then subjected to a third cleaning using a second alkaline solution, followed by annealing to obtain an annealed steel coil; wherein,

[0047] The chloride ion content in the second alkaline solution is ≤20mg / L, and / or the temperature of the second alkaline solution is 70~80℃.

[0048] In this embodiment, the surface of the pickled (hydrochloric acid) or cold-rolled steel sheet is coated with oil or production is arranged in a timely manner to prevent rusting. The oil is a common rust-preventive oil.

[0049] Before annealing the aforementioned cold-rolled steel plates, alkaline washing is performed. Controlling the chloride ion content in the alkaline solution to ≤20 mg / L has the following positive effects: preventing corrosion caused by excessive chloride ions. Specifically, the chloride ion content can be 20 mg / L, 19 mg / L, 18 mg / L, etc. Controlling the temperature of the alkaline solution to 70–80℃ has the following positive effects: alkaline degreasing and cleaning during steel plate production removes surface grease and impurities, improving the cleanliness of the steel plate surface and thus enhancing the effectiveness of subsequent processing. Increasing the alkaline solution temperature can further enhance the degreasing and cleaning effect. However, if the alkaline solution temperature is too high, it may also cause some corrosion to the steel plate surface. Specifically, the alkaline solution temperature can be 70℃, 75℃, 80℃, etc. Simultaneously control the brush roller current (15-35) A, the conductivity of the spraying circulation tank (30-40) ms, and the conductivity of the electrolytic circulation tank (65-75) ms to achieve the alkaline washing effect, remove the oil or rolling oil from the surface of the cold-hardened coiled steel sheet, and verify the cleaning quality by testing the reflectivity of the strip surface with a reflectivity meter to ensure it is ≥90%.

[0050] S2. The annealed steel coil after water quenching is cleaned in stages and then tin-plated to obtain tin-plated steel sheet.

[0051] In some embodiments, the step of performing staged cleaning on the water-quenched annealed steel coil, followed by tin plating to obtain tin-plated steel sheet, includes:

[0052] The first stage of cleaning was performed on the water-quenched annealed steel coil using a first alkaline solution, followed by a second stage of cleaning using an acid solution.

[0053] The annealed steel coil after the second stage cleaning is tin-plated to obtain tin-plated steel sheet; wherein,

[0054] The concentration of the first alkaline solution is 27-37 g / L, and the temperature of the first alkaline solution is 70-80℃; and or,

[0055] The concentration of the acid solution is 40-50 g / L, and the temperature of the acid solution is 45-55℃.

[0056] The first alkaline solution can be sodium hydroxide, with a concentration of 27-37 g / L and a temperature of 70-80℃. The positive effects of alkaline degreasing during steel plate production include: removing surface grease and impurities, improving surface cleanliness, and thus enhancing the effectiveness of subsequent processing. Increasing the alkaline concentration and temperature further enhances the degreasing effect, with the following positive benefits: Increased degreasing speed: Higher alkaline concentration and temperature accelerate the dissolution, separation, and removal of oil and dirt from the steel plate surface, thus increasing the degreasing speed; Improved cleaning quality: Increased alkaline concentration and temperature enhance the chemical reactivity of the cleaning solution, making it easier to react with grease and other contaminants and separate them from the steel plate surface, thereby improving cleaning quality; Water conservation: Increased alkaline concentration and temperature reduce the amount of cleaning agent used and cleaning time, thus saving water and being more environmentally friendly. Increasing the concentration and temperature of the alkaline solution may cause some corrosion to the steel plate surface. Therefore, while ensuring the degreasing and cleaning effect, it is necessary to control the cleaning time and temperature to prevent over-cleaning and damage to the steel plate surface quality. This temperature and concentration range will not cause damage to the steel plate surface and will not produce steel plate cleaning defects. Specifically, the concentration of the alkaline solution can be 27g / L, 30g / L, 33g / L, 37g / L, etc., and the temperature of the alkaline solution can be 70℃, 75℃, 80℃, etc.

[0057] In the first stage of the above-mentioned phased cleaning process: the cold-rolled tin-plated substrate (annealed coil) is immersed in an alkaline solution using sodium hydroxide. Oil and dirt on the strip surface are removed through saponification, electrochemical action, spray alkaline washing, and electrolytic alkaline washing. This includes two alkaline spray tanks, four electrolytic degreasing tanks, and three rinsing tanks. The alkaline solution concentration is (32±5) g / L, the electrolytic alkaline washing conductivity is (38±6) μS / cm, the alkaline solution temperature is (70-80)℃, and the current density is (25±3) A / dm³. 2 Rinsing medium: desalinated water; temperature: 45±5℃; spray pressure: 1.5 kg / cm² 2 The above information pertains to continuous overflow and discharge during normal production.

[0058] The acid solution can be H2SO4. Controlling the concentration of this acid solution to 40-50 g / L and the temperature to 45-55℃ has the following positive effects: Removal of surface contaminants and oxides: Pickling effectively removes oil, rust, dust, and other impurities from metal surfaces, making the steel plate surface clean and smooth, thus providing a good foundation for electroplating. Optimization of metal surface structure: Pickling has a certain influence on the microstructure of the steel plate surface, eliminating intergranular defects, voids, and other undesirable structures, thereby improving the uniformity and quality of the steel plate surface, which is beneficial to the formation and adhesion of the electroplated layer. Control of electroplated layer thickness and uniformity: Pickling can remove undesirable surface impurities, resulting in better wettability and fluidity of the electroplating solution on the steel plate surface, promoting the formation and growth of the electroplated layer, and controlling the thickness and uniformity of the electroplated layer. Enhanced corrosion resistance: Pickling can eliminate oxides and other corrosive substances on the steel plate surface, reducing the surface energy of the steel plate, making it less susceptible to corrosion by the atmosphere, moisture, and acid / alkali media, thus enhancing the corrosion resistance of tin-plated steel plates. During pickling, the pickling concentration and temperature must be strictly controlled to avoid over-pickling or under-pickling, which would affect the quality and effect of the electroplating layer. This temperature and concentration range will not damage the steel plate surface or cause defects due to pickling. Specifically, the concentration of the acid solution can be 40g / L, 45g / L, 50g / L, 37g / L, etc., and the temperature of the acid solution can be 45℃, 50℃, 55℃, etc.

[0059] In the second stage of the above-mentioned phased cleaning process: the tin-plated substrate after alkaline washing is immersed in a sulfuric acid solution to remove microscopic rust products from the steel plate surface and to activate the steel plate surface, providing a good surface for electroplating. Four pickling tanks are used. H2SO4 concentration: (45±5) g / L (5–8%), Fe 2+ Concentration: below 10 g / L, temperature (50±5)℃.

[0060] The above tin plating steps include pre-plating and electroplating. The purpose of pre-plating is to prevent iron ions from being introduced into the electroplating bath and contaminating the electroplating solution, while also activating the surface of the steel strip. Electroplating involves immersing the pre-plated steel sheet in a methanesulfonate plating solution to plate a low-tin layer of tin-plated steel sheet.

[0061] Pre-plating pretreatment solution concentration (4±2) ml / L MSA solution, iron ions Fe 2+ ≤2g / L, temperature control (45±5)℃.

[0062] Sn in electroplating solution 2+ The concentration was 20±3 g / L, the free acid concentration was 45±5 g / L, and the current density was 45-55 A / dm³. 2The additive content is 20±3ml / L, and the additive concentration is 25±5g / L. The parameters of the electroplating solution can ensure the uniform plating ability and deep plating ability of the electroplating solution, and can form a dense and uniform tin grain layer on the surface of the steel plate and in the pit.

[0063] During this tin plating process, the steel plate runs at a speed of 400–450 m / min. The surface roughness of the low-tin-weight tinplate is determined according to customer requirements and product application. The steel plate thickness ranges from 0.12 to 0.50 mm. The tin layer thickness of this steel plate is less than 2.8 g / m².

[0064] S3. The tin-plated steel sheet is softened using a flux, and the softening temperature is set according to the thickness of the tin-plated steel sheet.

[0065] In some embodiments, setting the remelting temperature based on the thickness of the tin-plated steel sheet includes:

[0066] If the thickness of the tin-plated steel sheet is 0.12-0.25mm, then the temperature of the remelting is set as the first temperature;

[0067] If the thickness of the tin-plated steel sheet is 0.26-0.35mm, then the remelting temperature is set as the second temperature;

[0068] If the thickness of the tin-plated steel sheet is 0.36-0.55mm, then the remelting temperature is set as the third temperature.

[0069] After softening, the strip is quenched in water. The heated strip is cooled by the quenching water to stabilize the diffusion of the iron-tin alloy layer, achieving a certain alloy layer thickness. To prevent splashing during quenching and ensure a good quenching effect, the nozzle angle in the quenching tank needs to be adjusted appropriately according to the process requirements. The quenching temperature is controlled at (85±10)℃ in production, and appropriate adjustments are made to obtain a strip surface with a good gloss after quenching.

[0070] In some embodiments, the first temperature is 250-290°C, and / or the second temperature is 245-285°C, and / or the third temperature is 240-275°C.

[0071] If the thickness of the tin-plated steel sheet is 0.12-0.25mm, the softening temperature is controlled at 250-290℃. Specifically, this softening temperature can be 250℃, 260℃, 270℃, 280℃, 290℃, etc. If the thickness of the tin-plated steel sheet is 0.26-0.35mm, the softening temperature is controlled at 245-285℃. Specifically, this softening temperature can be 245℃, 260℃, 270℃, 280℃, 285℃, etc. If the thickness of the tin-plated steel sheet is 0.36-0.55mm, the softening temperature is controlled at 240-275℃. Specifically, this softening temperature can be 240℃, 250℃, 260℃, 275℃, etc.

[0072] The reflow process used in the production of tinplate, employing the aforementioned reflow temperature, offers several positive effects: Ensuring plating quality: The reflow process heats the surface of the tinplate to a specific temperature, melting the surface layer and forming a relatively uniform and dense tin layer. A suitable temperature ensures the molten tin has good fluidity and filling properties, allowing for better coating onto the substrate surface and the formation of a uniform plating layer. Uneven tin layers are prone to corrosion. Improving plating adhesion: A suitable reflow temperature also promotes the affinity of the molten tin to the substrate surface, helping to improve plating adhesion. If the reflow temperature is too high, the molten tin's fluidity will increase excessively, exceeding the coating area, resulting in problems such as droplets or bubbles, affecting plating quality. Excessively high temperatures can also cause the substrate to harden and become brittle, making it prone to deformation and failure during production. If the reflow temperature is too low, the surface cannot melt, resulting in increased viscosity of the coated molten tin, poor fluidity, and uneven coating thickness, affecting the overall quality of the tinplate. Low temperatures can also cause problems with coating adhesion. Insufficient affinity of molten tin leads to unstable adhesion, making it easy for the coating to peel off during use.

[0073] In some embodiments, the flux is demineralized water.

[0074] The positive effects of using desalinated water as a fluxing agent: Desalinated water fluxing significantly improves the density and rust resistance of the tinplate coating, without significantly affecting other product properties. This is because in high-speed electroplating tin, the porosity of the tin layer determines the corrosion resistance of the tinplate. Softening, by heating to above the melting point of tin (231.9℃) within seconds, allows the tin to smooth out micropores, improving not only the gloss and adhesion of the tin layer but also the corrosion resistance of the tinplate. Fluxes can alter the smoothing effect of tin during the softening process, significantly impacting the corrosion resistance of the tinplate. Using desalinated water fluxing improves the tinplate's resistance to pitting rust because the increased density of the tin layer after desalinated water fluxing enhances its properties.

[0075] S4. Passivate the tin-plated steel sheet after softening and then apply oil to obtain the tin-plated steel sheet product.

[0076] In some embodiments, the passivation of the tin-plated steel sheet after remelting, followed by oiling to obtain the tin-plated steel sheet product, includes:

[0077] The tin-plated steel sheet after softening and melting is passivated, and the process parameters of the passivation solution used in the passivation process are controlled. Then, oil is applied to obtain the tin-plated steel sheet product. The process parameters of the passivation solution include: the concentration of the passivation solution, the pH value of the passivation solution, and the temperature of the passivation solution.

[0078] In some embodiments, the concentration of the passivation solution is 25-31 g / L, the pH value of the passivation solution is 4.1-4.5, and the temperature of the passivation solution is 43-47°C.

[0079] The tin-plated steel sheet undergoes passivation treatment after remelting to improve its surface corrosion resistance. The passivation solution is sodium dichromate. Depending on the customer's application, either chemical or electrochemical passivation methods can be used, with careful control of the remelting parameters. The passivation current density can be set from 0.3 to 1.7 ASD, while chemical passivation can be set to 0.

[0080] The positive effects of controlling the passivation solution concentration to 25-31 g / L: The concentration of the passivation solution directly affects the quality and thickness of the passivation film. If the passivation solution concentration is too low, the passivation film will be too thin, which is not conducive to protecting the tin-plated board; if the passivation solution concentration is too high, defects such as clumps and watermarks are easily formed on the surface. Specifically, the concentration of the passivation solution can be 25 g / L, 27 g / L, 29 g / L, 31 g / L, etc.

[0081] The positive effects of controlling the pH of the passivation solution to 4.1-4.5: The pH value of the passivation solution affects the composition, structure, and stability of the passivation film. Generally, the suitable pH value is between 2.0 and 3.0. A pH value that is too high or too low will affect the passivation effect of the passivation solution, leading to unstable passivation film quality or even failure. Specifically, the pH value of the passivation solution can be 4.1, 4.3, 4.5, etc.

[0082] The positive effects of controlling the passivation solution temperature to 43-47℃: The passivation solution temperature directly affects the composition, structure, and quality of the passivation film. Excessively high or low passivation solution temperatures can lead to uneven passivation films, and in severe cases, quality problems. Specifically, the passivation solution temperature can be 43℃, 45℃, 47℃, etc. Therefore, good passivation solution concentration, pH, and temperature can ensure the composition, quality, and stability of the passivation film, and positively impact the mechanical properties, corrosion resistance, and other performance indicators of the tinplate.

[0083] In some embodiments, the amount of oil used for oiling is 2.0-6.0 mg / m³. 2 .

[0084] Electrostatic oiling requires careful control of the oil application parameters; food-grade protective oil DOS-A is used. Applying a suitable protective lubricating oil film to the tinplate surface prevents scratches during transportation and high-speed can manufacturing, while also providing rust prevention. The oil application rate should be controlled at 2.0-6.0 mg / m³. 2 The positive effects include a balance between lubrication and rust prevention. Specifically, the oil dosage can be 2.0 mg / m³. 2 2.3 mg / m 2 2.6 mg / m 2 The difference in oil application rate along the width of the board is less than 0.3 mg / m². 2 This ensures that the surface tension, contact angle, and surface free energy of the cold-rolled tin-plated steel sheet are optimized, providing a guarantee for subsequent painting, printing, and forming processes.

[0085] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0086] Table 1. Manufacturing process parameters of tin-plated steel sheet

[0087]

[0088] Table 2 Surface property results of tinplate

[0089]

[0090] As shown in Tables 1 and 2, the tin-plated sheet prepared using the method of this application embodiment exhibits excellent corrosion resistance, while the tin-plated sheet prepared in Comparative Example 1, which did not use the method of this application embodiment, has poor corrosion resistance. Salt spray tests were used to compare the corrosion resistance performance. Figure 3 It can be seen that the tin-plated steel sheet prepared using the embodiments of this application has good corrosion resistance and does not produce dense rust spots; while from Figure 2 It can be seen that the tin-plated steel sheet prepared by Comparative Example 1, which did not use the method of the embodiments of this application, has poor corrosion resistance and produces dense rust spots.

[0091] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for producing a tinplate characterized by, The method includes: performing a third cleaning on the steel coil using a second alkaline solution, followed by annealing to obtain an annealed steel coil, wherein the chloride ion content in the second alkaline solution is ≤20mg / L, and the temperature of the second alkaline solution is 70~80℃; The annealed steel coil was water quenched, and the chloride ion content and conductivity of the solution used in the water quenching process were controlled to be <10 mg / L and <10 μs / cm. The annealed steel coil after water quenching is cleaned in the first stage using a first alkaline solution, followed by a second stage using an acid solution. The concentration of the first alkaline solution is 27-37 g / L, and the temperature of the first alkaline solution is 70-80℃; the concentration of the acid solution is 40-50 g / L, and the temperature of the acid solution is 45-55℃. The annealed steel coil after the second stage of cleaning is tin-plated to obtain tin-plated steel sheet; The tin-plated steel sheet is softened using demineralized water as a flux, and the softening temperature is set according to the thickness of the tin-plated steel sheet. The tinned steel sheet after the softening is passivated, and then is oiled to obtain a tinned steel sheet product. The concentration of the passivation solution used in the passivation is 25-31 g / L, the pH value is 4.1-4.5, the temperature is 43-47 ℃, and the oiling amount is 2.0-6.0 mg / m 2 The tin layer thickness of the tinned steel sheet product is 2.8 g / m 2 Below.

2. The method of claim 1, wherein, The step of setting the remelting temperature based on the thickness of the tin-plated steel sheet includes: If the thickness of the tin-plated steel sheet is 0.12-0.25mm, then the remelting temperature is set to 250-290℃; If the thickness of the tin-plated steel sheet is 0.26-0.35mm, then the remelting temperature is set to 245-285℃; If the thickness of the tin-plated steel sheet is 0.36-0.55mm, then the remelting temperature is set to 240-275℃.

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