A tinplate for beer cans and a method for manufacturing the same

Abstract

This invention belongs to the field of alloy materials technology, specifically relating to a tin-plated sheet for beer cans and its preparation method. The preparation method includes the following steps: annealing, leveling, surface activation, pre-wetting, pre-plating indium, electroplating, remelting, quenching, sterilization, passivation, and oiling of a substrate to obtain the tin-plated sheet for beer cans. In this invention, pre-wetting improves the plating applicability and uniformity of the substrate, enhancing the coating quality; the pre-plated indium and the electroplated metal undergo a remelting process to obtain an alloy layer with good ductility and fluidity, reducing porosity; the tin-plated sheet for beer cans is prepared layer by layer in situ through multiple steps, resulting in a stronger bond between the film layers, resisting deformation during the processing of the tin-plated sheet into beer packaging cans, and exhibiting good impact resistance, low iron leaching, and preservation of the beer's excellent flavor.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials technology, specifically relating to a tin-plated sheet for beer cans and its preparation method. Background Technology

[0002] Tinplate is an important raw material for manufacturing food and beverage cans, characterized by its ease of welding, processing, environmental friendliness, and aesthetic appeal. In the food and beverage packaging industry, tinplate is widely used to maintain product flavor. However, the micropores of the tin plating layer can become a problem, especially in beer packaging. If the substrate beneath the tin plating comes into contact with the beer, trace amounts of iron ions can dissolve. These precipitated iron ions accelerate the aging of beer, particularly craft beer, severely impacting its taste and flavor, resulting in a poor drinking experience for consumers.

[0003] In addition, the process of processing beer cans into beer packaging cans using tinplate involves multiple steps such as shearing, rounding, necking, flanging, and welding. These steps will produce varying degrees of deformation, which will severely test the adhesion between the coating layer and the tinplate, and may lead to the expansion and increase in the number of micropores in the material, thus exacerbating iron leaching. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of iron leaching in existing beer can materials, thereby providing a tin-plated sheet for beer cans and its preparation method.

[0005] Therefore, the present invention provides the following technical solution:

[0006] The first aspect of this invention protects a method for preparing a tin-plated sheet for beer cans, wherein the preparation method includes the following steps: annealing, flattening, surface activation, pre-wetting, pre-plating indium, electroplating, remelting, quenching, sterilization, passivation, and oiling the substrate to obtain the tin-plated sheet for beer cans.

[0007] In this invention, the substrate is a conventional substrate in the art. Typically, without limitation, the substrate thickness is 0.180-0.190 mm, and based on the mass percentage of chemical composition, the substrate comprises: C: 0.042-0.048%; Si: 0.001-0.002%; Mn: 0.15-0.20%; P: 0.007-0.009%; S: 0.007-0.009%; Cr: 0.007-0.009%; Ni: 0.07-0.09%; Cu: 0.07-0.09%; Al: 0.03-0.05%; the remainder being iron and unavoidable impurity elements.

[0008] In one alternative embodiment, the pre-wetting includes the following step: completely submerging the surface-activated substrate with a mixed solution of phytic acid and sodium phytate.

[0009] In one optional embodiment, the concentration of phytic acid, calculated as a mixed solution, is 5-10 g / L, and the concentration of sodium phytate is 20-25 g / L. As an example, the concentration of phytic acid can be 5 g / L, 7 g / L, 9 g / L, 10 g / L, or within any range of these values, and the concentration of sodium phytate can be 20 g / L, 22 g / L, 24 g / L, 25 g / L, or within any range of these values.

[0010] In one optional embodiment, the pre-impregnation temperature is 30-50°C, and the pre-impregnation time is 1-1.5 seconds. As an example, the pre-impregnation temperature can be 30°C, 35°C, 40°C, 45°C, 50°C, or any range thereof, and the pre-impregnation time can be 1 second, 1.1 seconds, 1.2 seconds, 1.3 seconds, 1.4 seconds, 1.5 seconds, or any range thereof.

[0011] In one alternative embodiment, the pre-plating of indium includes the following steps: completely submerging the pre-wetted substrate with a mixed solution containing indium salt, supporting electrolyte, and additives.

[0012] In one optional embodiment, the concentration of the indium salt, calculated as a mixed solution, is 80-100 g / L, the concentration of the supporting electrolyte is 8-10 g / L, and the concentration of the additive is 3-5 g / L. As an example, the concentration of the indium salt can be 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, or within any range of these values; the concentration of the supporting electrolyte can be 8 g / L, 8.5 g / L, 9 g / L, 9.5 g / L, 10 g / L, or within any range of these values; and the concentration of the additive can be 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, or within any range of these values.

[0013] In one optional embodiment, the indium-containing salt includes at least one of indium aminosulfonate and indium sulfate, and may be indium aminosulfonate.

[0014] In one optional embodiment, the supporting electrolyte includes at least one of sodium sulfate and potassium sulfate, optionally sodium sulfate.

[0015] In one optional embodiment, the additive includes at least one of acetylenic diol polyoxyethylene ether and dodecyl acetylenic diol polyoxyethylene ether, optionally acetylenic diol polyoxyethylene ether.

[0016] In one alternative embodiment, the pH of the mixed solution is 2-3, and the pH is generally adjusted using an acid having the same anion as that in the indium salt. Typically, without limitation, indium sulfate is treated with dilute sulfuric acid (concentration of 0.1-5 mol / L), and indium aminosulfonate is treated with aminosulfonic acid.

[0017] In one optional embodiment, the indium pre-plating temperature is 20-30°C, and the current density is 1.5-2 A / dm². 2 As an example, the indium pre-plating temperature can be 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, or within any range of these values; the current density can be 1.5 A / dm³. 2 1.6A / dm 2 1.7A / dm 2 1.8A / dm 2 1.9A / dm 2 2A / dm 2 , or within the range of any of the above values.

[0018] In one alternative embodiment, the leveling is performed using a dual-stand system, with each stand having identical upper and lower work rollers; wherein the arithmetic mean roughness of the upper and lower work rollers of one stand is 0.6-1.0 μm, the profile skewness is -0.5 to 0, and the profile kurtosis is 0-3; as an example, the arithmetic mean roughness of the upper and lower work rollers of one stand can be 0.6 μm, 0.8 μm, 1.0 μm, or within any range of the above values; the profile skewness can be -0.5, -0.3, 0, or within any range of the above values; and the profile kurtosis can be 0, 1, 2, 3, or within any range of the above values. Within the range of values; the arithmetic mean roughness of the upper and lower work rolls of the two-stand mill is 0.65-0.95μm, the profile skewness is -0.2 to 0.2, and the profile kurtosis is 0-3; as an example, the arithmetic mean roughness of the upper and lower work rolls of the two-stand mill can be 0.65μm, 0.75μm, 0.85μm, 0.95μm, or within any of the above values; the profile skewness can be -0.2, -0.1, 0.1, 0.2, or within any of the above values; the profile kurtosis can be 0, 1, 2, 3, or within any of the above values.

[0019] In one alternative embodiment, the surface activation includes alkaline washing and acid washing.

[0020] In one optional embodiment, the alkaline washing uses a mixed solution of NaOH, NaHCO3, and Na2HPO4, wherein the concentration of NaOH is 30-45 g / L, the concentration of NaHCO3 is 5-15 g / L, and the concentration of Na2HPO4 is 5-10 g / L.

[0021] In one optional embodiment, the alkaline washing temperature is 40-45°C, and the alkaline washing time is 1-1.2 seconds.

[0022] In one alternative embodiment, the pickling includes chemical pickling and electrochemical pickling.

[0023] In one optional embodiment, the chemical pickling uses a mixed solution of H2SO4 and H3PO4, wherein the concentration of H2SO4 is 45-60 g / L and the concentration of H3PO4 is 20-25 g / L, based on the mixed solution.

[0024] In one optional embodiment, the chemical pickling temperature is 40-50°C and the time is 0.8-1s.

[0025] In one optional embodiment, the electrochemical pickling uses an H2SO4 solution with a concentration of 30-40 g / L.

[0026] In one optional embodiment, the electrochemical pickling temperature is 55-70°C, the time is 0.8-1.2 s, and the current density is 10-12 A / dm³. 2 .

[0027] In one optional embodiment, the electroplating uses an MSA (methanesulfonic acid) plating solution, wherein the concentration of MSA is 110-125 g / L, the concentration of free acid is 20-38 mL / L, and the Sn in the solution... 2+ The concentration of ions is 30-45 g / L, Fe 2+ The concentration of ions is 0-50 ppm.

[0028] In this invention, free acid refers to MSA that exists freely without being bound to metal ions; part of the methanesulfonic acid in the plating solution is bound to metal ions to form salts, while the other part is unbound and remains free methanesulfonic acid; the free acid is titrated with standard NaOH solution using an acid-base titration method, and the volume of NaOH consumed is defined as the concentration of the free acid, hence the unit is mL / L, which is different from the unit g / L for the concentration of methanesulfonic acid.

[0029] In one optional embodiment, the temperature of the electroplating solution is 40-45°C, the anode is a soluble pure tin anode with a tin content of 99.99%-100%, and the current density is 12-20 A / dm³. 2 .

[0030] In one optional embodiment, the softening temperature is 255-270°C and the time is 0.8-1.8 seconds.

[0031] In one optional embodiment, the temperature of the quenching water is 70-80°C, and the time is 0.5-0.8s.

[0032] In this invention, water quenching is a conventional operation in the field. Generally, demineralized water is used for water quenching, and the conductivity of the demineralized water is κ, 0<κ≤8μS / cm.

[0033] In one optional implementation, a mixture of ozone-containing gases is used for sterilization at a temperature of 20-30°C for 1-2 seconds.

[0034] In one optional embodiment, the ozone concentration in the mixed gas is 1-2 ppm. Ozone-containing mixed gas is generally prepared by introducing ozone into the air. Since the original ozone concentration in the air is low, the concentration of introduced ozone is used to approximate the ozone-containing mixed gas. The specific ozone concentration in this invention can prevent excessive oxidation, allowing a complete, stable, and extremely thin layer of tin oxide to actively form on the surface of the tin plating layer (in addition to oxidizing stannous oxide, it also includes oxidizing metallic tin to tin oxide), avoiding excessively thick local oxide films caused by uncontrolled tin oxidation (which easily leads to increased film brittleness).

[0035] In one alternative embodiment, the passivation is performed using a mixed solution of CrO3 and Ce2(SO4)3, wherein the concentration of CrO3 is 35-40 g / L and the concentration of Ce2(SO4)3 is 0.35-0.8 g / L, based on the mixed solution.

[0036] In this invention, compared with the traditional passivation method, chromium salt and cerium salt are used for synergistic passivation, which improves the density and coatability of the passivation film, thereby reducing the overall porosity of the finished product and reducing brittleness, which is beneficial for coping with deformation and impact during subsequent processing and use.

[0037] In one optional embodiment, the passivation temperature is 40-42°C, and the passivation current density is 50-55 A / dm². 2 .

[0038] In one optional embodiment, the passivation amount, calculated as Cr, is 10-20 mg / m³. 2 .

[0039] In this invention, a vertical electrostatic oiling method is used, the reagent is DOS-A oil (dioctyl sebacate type A oil), and the oiling amount is 2-4 mg / m². 2 With an oil temperature of 40-42°C and a voltage of 15-20kV, tin-plated sheets for beer cans are obtained.

[0040] The second aspect of this invention protects the tin-plated sheet for beer cans prepared by the aforementioned preparation method.

[0041] In one optional embodiment, the tin-plated plate for beer cans includes a first passivation layer, a first tin plating layer, a first multi-element alloy layer, a substrate layer, a second multi-element alloy layer, a second tin plating layer, and a second passivation layer disposed sequentially.

[0042] In one alternative embodiment, the tinplate for the beer can has an arithmetic mean roughness of 0.50-0.65 μm, a profile skewness Rsk of -0.5 to 0.5, and a profile kurtosis of 0-3.

[0043] Optionally, the tinplate for beer cans has an arithmetic mean roughness of 0.58-0.65 μm, a profile skewness of -0.1 to 0.1, and a profile kurtosis of 1.5-2.

[0044] In one optional embodiment, the tin-plated sheet for the beer can has a tin content of 0.50-2.00 g / m³. 2 As an example, the tin content in the tin-plated sheet used for the beer can may be 0.50 g / m². 2 0.80g / m 2 1.10g / m 2 1.50g / m 2 1.80g / m 2 1.90g / m 2 , or within the range of any of the above values.

[0045] In one optional embodiment, the indium content in the tin-plated sheet for the beer can is 20-80 mg / m³. 2 As an example, the indium content in the tin-plated sheet used for the beer can may be 20 mg / m³. 2 30mg / m 2 40mg / m 2 50mg / m 2 60mg / m 2 70mg / m 2 80mg / m 2 , or within the range of any of the above values.

[0046] In one alternative embodiment, the tinplate used for beer cans has an adhesion rating of 1 and an impact resistance rating of 1.

[0047] The technical solution of this invention has the following advantages:

[0048] This invention provides a method for preparing a tin-plated sheet for beer cans. The method includes the following steps: annealing, planing, surface activation, pre-wetting, pre-plating indium, electroplating, reflowing, quenching, sterilization, passivation, and oiling of a substrate to obtain the tin-plated sheet for beer cans. In this invention, pre-wetting enhances the surface activity and wettability of the substrate, thereby improving its plating suitability and uniformity. This results in a more uniform and dense electroplating process with smaller pores, thus improving the plating quality. Simultaneously, it provides a good substrate for preparing the next layer, enhancing interlayer bonding. The process involves a multi-step in-situ preparation of tinplate for beer cans. This process reduces the iron leaching value by using pre-plated indium and electroplated metals in a soft melting process to create an alloy layer with good ductility and fluidity, reducing micropores and providing a good substrate for the next layer. The resulting coating layer and the tinplate itself have good impact resistance and low iron leaching, allowing the beer to maintain its excellent flavor after being filled. Detailed Implementation

[0049] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0050] 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 invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having” and any variations thereof in the text of this invention are intended to cover non-exclusive inclusion.

[0051] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0052] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0053] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This range can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] In the description of the embodiments of the present invention, the term "and / or" is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0055] In the description of the embodiments of the present invention, the term "at least one" refers to one or more (including two).

[0056] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0057] Example 1

[0058] This embodiment provides a tin-plated sheet for beer cans, and the preparation method includes the following steps:

[0059] (1) The thickness of the substrate is 0.190 mm. Based on the mass percentage of chemical composition, the substrate includes C: 0.042%; Si: 0.001%; ​​Mn: 0.15%; P: 0.008%; S: 0.009%; Cr: 0.007%; Ni: 0.07%; Cu: 0.07%; Al: 0.05%; the remainder is iron and unavoidable impurity elements.

[0060] (2) Annealing: The annealing temperature is 642°C, the annealing time is 25s, the annealing dew point is -38°C, and the annealing atmosphere is a mixture of N2 and H2. The concentration of H2 is 17%, the concentration of N2 is 83%, the concentration of impurity gas is 0.7ppmv, and the concentration of O2 is 1ppmv, based on the mass of the mixture.

[0061] (3) Smoothing: The arithmetic mean roughness of the upper and lower working rollers of the first frame is 0.85μm, the profile skewness is -0.25, and the profile kurtosis is 2.3; the arithmetic mean roughness of the upper and lower working rollers of the second frame is 0.80μm, the profile skewness is 0, and the profile kurtosis is 2.1.

[0062] (4) Alkali washing: The solution is a mixed solution of sodium hydroxide (NaOH), sodium bicarbonate (NaHCO3) and disodium hydrogen phosphate (Na2HPO4). The concentration of NaOH is 45 g / L, the concentration of NaHCO3 is 5 g / L, and the concentration of Na2HPO4 is 5 g / L. The mixed solution completely covers the flattened substrate. The temperature of alkali washing is 42℃ and the time of alkali washing is 1 s.

[0063] (5) Pickling: Pickling is carried out in two steps. The first step is chemical pickling, using a mixed solution of sulfuric acid (H2SO4) and phosphoric acid (H3PO4). The concentration of H2SO4 is 60 g / L and the concentration of H3PO4 is 20 g / L. The mixed solution completely submerges the substrate after alkaline pickling. The pickling temperature is 45℃ and the pickling time is 0.8 s. The second step is electrochemical pickling, using a 35 g / L H2SO4 solution. The H2SO4 solution completely submerges the substrate after the first step of pickling. The current density is 10 A / dm³. 2 The pickling temperature was 60℃, and the pickling time was 1.2s.

[0064] (6) Pre-wetting: Phytic acid (C6H) is used. 18 O 24 P6) and sodium phytate (C6H6Na) 12 O 24 A mixed solution of P6), calculated as a mixed solution, C6H 18 O 24 The concentration of P6 is 8.5 g / L, C6H6Na 12 O 24 The concentration of P6 is 25 g / L. The mixed solution completely submerges the acid-washed substrate. The pre-wetting temperature is 45°C and the pre-wetting time is 1.2 s.

[0065] (7) Indium pre-plating, the pre-plating solution is indium aminosulfonate (H6InN3O9S3), sodium sulfate (Na2SO4) and acetylenol polyoxyethylene ether (C 16 H 30 A mixed solution of H6InN3O9S3 (based on the mixed solution) has a concentration of 82 g / L, a concentration of Na2SO4 of 8 g / L, and a concentration of C... 16 H 30 The concentration of O6 was 3.5 g / L. The pre-plating solution completely submerged the pre-wetted substrate. The temperature of the pre-plating solution was 25°C, the pH value was 2.1, and the current density was 1.5 A / dm³.2 ;

[0066] (8) Electroplating: The electroplating solution is an MSA plating solution with an MSA concentration of 118 g / L and a free acid concentration of 30 mL / L. Sn 2+ The ion concentration is 35 g / L, Fe 2+ The ion concentration was 43 ppm, the anode was a soluble pure tin anode with a tin content of 99.995%, the electroplating solution completely submerged the substrate after indium plating, the temperature of the electroplating solution was 42°C, and the current density was 15 A / dm³. 2 The tin plating amount is 1.1 g / m 2 ;

[0067] (9) Soft melting: High-frequency pure inductive soft melting is used. The soft melting temperature is 260°C, the N2 concentration in the soft melting atmosphere is 99%, and the soft melting time is 0.8s, so as to form a multi-element alloy layer.

[0068] (10) Quenching: Quenching is carried out immediately after softening. The temperature of the quenching water is 70°C and the quenching time is 0.6s. The quenching water solution is desalinated water with a conductivity of 6μS / cm.

[0069] (11) Sterilization: After quenching, a mixture of ozone-containing gas is used for sterilization, with an ozone concentration of 1.5 ppm, and sterilization is carried out at 25°C for 1 second;

[0070] (12) Passivation: A mixed solution of chromium anhydride (CrO3) and cerium sulfate (Ce2(SO4)3) was used. The concentration of CrO3 was 35 g / L and the concentration of Ce2(SO4)3 was 0.35 g / L, based on the mixed solution. The passivation temperature was 40°C and the passivation current density was 50 A / dm³. 2 The passivation amount, calculated as Cr, is 18 mg / m³. 2 ;

[0071] (13) Oiling: Vertical electrostatic oiling was used, with DOS-A oil as the reagent and an oiling amount of 2 mg / m². 2 With an oil temperature of 41°C and a voltage of 18kV, tin-plated sheets for beer cans were obtained.

[0072] Example 2

[0073] This embodiment provides a tin-plated sheet for beer cans, and the preparation method includes the following steps:

[0074] (1) The thickness of the substrate is 0.185 mm. Based on the mass percentage of chemical composition, the substrate includes C: 0.046%; Si: 0.001%; ​​Mn: 0.18%; P: 0.009%; S: 0.008%; Cr: 0.009%; Ni: 0.08%; Cu: 0.07%; Al: 0.04%; the remainder is iron and unavoidable impurity elements.

[0075] (2) Annealing: The annealing temperature is 645°C, the annealing time is 25s, the annealing dew point is -30°C, and the annealing atmosphere is a mixture of N2 and H2. The concentration of H2 is 18%, the concentration of N2 is 82%, the concentration of impurity gas is 0.8ppmv, and the concentration of O2 is 1ppmv, based on the mass of the mixture.

[0076] (3) Smoothing: The arithmetic mean roughness of the upper and lower working rollers of the first frame is 0.98 μm, the profile skewness is -0.33, and the profile kurtosis is 2.5; the arithmetic mean roughness of the upper and lower working rollers of the second frame is 0.89 μm, the profile skewness is -0.1, and the profile kurtosis is 2.3.

[0077] (4) Alkali washing: The solution is a mixed solution of sodium hydroxide (NaOH), sodium bicarbonate (NaHCO3) and disodium hydrogen phosphate (Na2HPO4). The concentration of NaOH is 30 g / L, the concentration of NaHCO3 is 15 g / L, and the concentration of Na2HPO4 is 10 g / L. The mixed solution completely covers the flattened substrate. The temperature of alkali washing is 45℃ and the time of alkali washing is 1.2 s.

[0078] (5) Pickling: Pickling is carried out in two steps. The first step is chemical pickling, using a mixed solution of sulfuric acid (H2SO4) and phosphoric acid (H3PO4). The concentration of H2SO4 is 60 g / L and the concentration of H3PO4 is 20 g / L. The mixed solution completely submerges the substrate after alkaline pickling. The pickling temperature is 48℃ and the pickling time is 0.8 s. The second step is electrochemical pickling, using a 40 g / L H2SO4 solution. The H2SO4 solution completely submerges the substrate after the first step of pickling. The current density is 12 A / dm³. 2 The pickling temperature is 60℃ and the pickling time is 1 second;

[0079] (6) Pre-wetting: Phytic acid (C6H) is used. 18 O 24 P6) and sodium phytate (C6H6Na) 12 O 24 A mixed solution of P6), calculated as a mixed solution, C6H 18 O 24 The concentration of P6 is 10 g / L, C6H6Na 12 O24 The concentration of P6 was 24 g / L. The mixed solution completely submerged the acid-washed substrate. The pre-wetting temperature was 44°C and the pre-wetting time was 1.2 s.

[0080] (7) Indium pre-plating, the pre-plating solution is indium aminosulfonate (H6InN3O9S3), sodium sulfate (Na2SO4) and acetylenol polyoxyethylene ether (C 16 H 30 A mixed solution of H6InN3O9S3 (based on the mixed solution) has a concentration of 86 g / L, a concentration of Na2SO4 of 10 g / L, and a concentration of C... 16 H 30 The concentration of O6 was 3.5 g / L. The pre-plating solution completely submerged the pre-wetted substrate. The temperature of the pre-plating solution was 25°C, the pH value was 2.5, and the current density was 1.8 A / dm³. 2 ;

[0081] (8) Electroplating: The electroplating solution is an MSA plating solution with an MSA concentration of 120 g / L and a free acid concentration of 35 mL / L. 2+ The ion concentration is 36 g / L, Fe 2+ The ion concentration was 32 ppm, the anode was a soluble pure tin anode with a tin content of 99.992%, the electroplating solution completely submerged the substrate after indium plating, the temperature of the electroplating solution was 42°C, and the current density was 14 A / dm³. 2 The tin plating amount is 2.0 g / m 2 ;

[0082] (9) Soft melting: High-frequency pure inductive soft melting is used. The soft melting temperature is 270°C, the N2 concentration in the soft melting atmosphere is 99%, and the soft melting time is 1.5s to form a multi-element alloy layer.

[0083] (10) Quenching: Quenching is carried out immediately after softening. The temperature of the quenching water is 72°C and the quenching time is 0.8s. The quenching water solution is desalinated water with a conductivity of 3μS / cm.

[0084] (11) Sterilization: After quenching, a mixture of ozone-containing gas is used for sterilization, with an ozone concentration of 1.9 ppm, and sterilization is carried out at 25°C for 1.8 s;

[0085] (12) Passivation: A mixed solution of chromium anhydride (CrO3) and cerium sulfate (Ce2(SO4)3) was used. The concentration of CrO3 was 39 g / L and the concentration of Ce2(SO4)3 was 0.4 g / L, based on the mixed solution. The passivation temperature was 41°C and the passivation current density was 52 A / dm³. 2 The passivation amount, calculated as Cr, is 15 mg / m³. 2 ;

[0086] (13) Oiling: Vertical electrostatic oiling was used, with DOS-A oil as the reagent and an oiling amount of 2.5 mg / m². 2 With an oil temperature of 42°C and a voltage of 19kV, tin-plated sheets for beer cans were obtained.

[0087] Comparative Example 1

[0088] This comparative example provides a tin-plated sheet for beer cans, the preparation method of which includes the following steps:

[0089] The method is the same as in Example 1, except that step (6) pre-wetting is omitted, that is, the substrate after pickling is directly pre-plated with indium; other conditions are the same as in Example 1.

[0090] Comparative Example 2

[0091] This comparative example provides a tin-plated sheet for beer cans, the preparation method of which includes the following steps:

[0092] The method is the same as in Example 1, except that step (7) of pre-plating indium is omitted, that is, the substrate after pre-wetting is directly electroplated; other conditions are the same as in Example 1.

[0093] Test case

[0094] The arithmetic mean roughness, profile skewness, and profile kurtosis of tinplate used for beer cans were tested using a contact surface roughness tester.

[0095] The test results are shown in Table 1;

[0096] Table 1 Arithmetic mean roughness, profile skewness, and profile kurtosis of tinplate used for beer cans

[0097]

[0098] Test method for tin and indium content of tin-plated sheets for beer cans: Mix water and hydrochloric acid (mass fraction 36%) at a volume ratio of 3:1 to obtain hydrochloric acid solution. At 80°C, completely immerse the tin-plated sheets of beer cans in the hydrochloric acid solution until the solution turns green. Measure the tin and indium content separately using ICP-OES.

[0099] The specific test results are shown in Table 2;

[0100] Table 2. Tin and Indium Content in Tinplate for Beer Cans

[0101]

[0102] As can be seen from the data in Table 2, the metal element content in the final tin-plated sheet used for beer cans is slightly lower than that used during electroplating. The inventors speculate that this is because multiple processing steps are performed after electroplating, resulting in some loss.

[0103] The adhesion rating of tinplate for beer cans was tested according to GB / T41899-2022.

[0104] The impact resistance of tinplate for beer cans was tested according to GB / T41899-2022.

[0105] The iron leaching value was tested according to GB4806.9-2023;

[0106] The test results are shown in Table 3;

[0107] Table 3 Adhesion grade, impact resistance grade, and iron leaching value of tinplate for beer cans

[0108]

[0109] Note: "-" indicates that it was not detected.

[0110] Comparing Example 1 and Comparative Example 1, it can be seen that pre-wetting increases the surface activity of the substrate, improves surface wettability, and thus improves the substrate's plating susceptibility and uniformity, making subsequent electroplating more uniform and dense with smaller pores, thereby improving the plating quality. At the same time, it provides a good substrate for the preparation of the next layer, which can enhance interlayer bonding and reduce iron dissolution value.

[0111] A comparison of Example 1 and Comparative Example 2 shows that the pre-plated indium and the electroplated metal, through a soft melting process, produce an alloy layer with good ductility and fluidity, reducing micropores and providing a good substrate for the preparation of the next layer, while reducing the iron dissolution value.

[0112] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a tin-plated sheet for beer cans, characterized in that, The preparation method comprises the following steps. Composition: The substrate is annealed, flattened, surface activated, pre-wetted, pre-plated with indium, electroplated, softened, quenched, sterilized, passivated, and oiled to obtain tin-plated sheet for beer cans; The pre-wetting includes the following steps: completely submerging the surface-activated substrate with a mixed solution of phytic acid and sodium phytate; The pre-plating of indium includes the following steps: completely submerging the pre-wetted substrate with a mixed solution containing indium salt, supporting electrolyte and additives; The indium-containing salt includes at least one of indium aminosulfonate and indium sulfate; The supporting electrolyte includes at least one of sodium sulfate and potassium sulfate; The additive includes at least one of acetylenic diol polyoxyethylene ether and dodecylenic diol polyoxyethylene ether.

2. The preparation method according to claim 1, characterized in that, The concentration of phytic acid is 5-10 g / L and the concentration of sodium phytate is 20-25 g / L, calculated as a mixed solution of phytic acid and sodium phytate. And / or, the pre-wetting temperature is 30-50°C, and the pre-wetting time is 1-1.5s.

3. The preparation method according to claim 1, characterized in that, The concentration of indium salt in the mixed solution is 80-100 g / L, the concentration of supporting electrolyte is 8-10 g / L, and the concentration of additive is 3-5 g / L. And / or, the pH of the mixed solution containing indium salt, supporting electrolyte and additive is 2-3; And / or, the indium pre-plating temperature is 20-30°C, and the current density is 1.5-2 A / dm³. 2 .

4. The preparation method according to claim 1, characterized in that, The indium-containing salt is indium aminosulfonate; And / or, the supporting electrolyte is sodium sulfate; And / or, the additive is acetylenic diol polyoxyethylene ether.

5. The preparation method according to claim 1, characterized in that, The leveling is performed using a dual-frame machine, with identical upper and lower work rollers on each frame. Specifically, the arithmetic mean roughness of the upper and lower work rollers on the first frame is 0.6-1.0 μm, the profile skewness is -0.5 to 0, and the profile kurtosis is 0-3. The arithmetic mean roughness of the upper and lower work rollers on the second frame is 0.65-0.95 μm, the profile skewness is -0.2 to 0.2, and the profile kurtosis is 0-3.

6. A tin-plated sheet for beer cans prepared by the method according to any one of claims 1-5.

7. The tin-plated sheet for beer cans according to claim 6, characterized in that, The tin-plated plate for beer cans includes a first passivation layer, a first tin plating layer, a first multi-element alloy layer, a substrate layer, a second multi-element alloy layer, a second tin plating layer, and a second passivation layer, arranged sequentially.

8. The tin-plated sheet for beer cans according to claim 7, characterized in that, The arithmetic mean roughness of the tin-plated sheet used for the beer can is 0.50-0.65 μm, the profile skewness is -0.5 to 0.5, and the profile kurtosis is 0-3. And / or, the tin content in the tin-plated sheet used for the beer can is 0.50-2.00 g / m³. 2 ; And / or, the indium content in the tin-plated sheet used for the beer can is 20-80 mg / m³. 2 ; And / or, the tinplate used for the beer can has an adhesion rating of Class 1 and an impact resistance rating of Class 1.

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