High sulfur resistance tinplate and preparation method and application thereof

Abstract

The application belongs to the technical field of tin-plated materials, and relates to a high-sulfur-resistance tin-plated plate and a preparation method and application thereof. The high-sulfur-resistance tin-plated plate comprises a first passivation layer, a first tin-plated layer, a first multi-element alloy layer, a tin-plated substrate layer, a second multi-element alloy layer, a second tin-plated layer and a second passivation layer arranged in sequence. The surface of the first passivation layer away from the first tin-plated layer is an inner coating surface. The surface of the second passivation layer away from the second tin-plated layer is an outer coating surface. The arithmetic average roughness of the inner coating surface is 0.4-0.5 microns, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3. The arithmetic average roughness of the outer coating surface is 0.6-0.7 microns, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3. The first multi-element alloy layer and the second multi-element alloy layer each independently comprise gallium. The high-sulfur-resistance tin-plated plate has strong bonding force between the film layers, excellent deformation resistance and excellent sulfur resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tin-plated materials, and particularly relates to a high-sulfur-resistance tin-plated plate and a preparation method and application thereof. BACKGROUND

[0002] As an important raw material for food and beverage packaging, the tin-plated plate has the characteristics of corrosion resistance and easy processing. Before filling, the tin-plated plate usually needs to be processed through steps such as shearing, coating printing and can making. During the processing, the tin-plated plate needs to undergo multiple deformations, and at the same time, the materials rub against each other and collide, so a high adhesion is needed to ensure the mechanical properties. After filling, the tin-plated plate also needs to be processed through steps such as sealing, cooking and rotary sterilization. Since food (such as eight-treasure rice porridge or milk) usually contains a certain amount of protein, sulfides are easily produced under high-temperature sterilization conditions, which poses a severe challenge to the adhesion of the outer coating and the sulfur resistance of the inner coating of the tin-plated plate.

[0003] The existing patent provides a method for improving the concentration, temperature and pH value of the sodium dichromate passivation solution, changing the plating current density, changing the thickness of the passivation film, obtaining different passivation film structures, meeting the adhesion requirement, improving the plating film quality of the tin-plated plate, and effectively improving the value of the product after coating. However, this method only focuses on improving the apparent adhesion of the outer coating of the tin-plated plate, ignoring the specific requirement of the eight-treasure rice porridge can inner coating for sulfur resistance, which may lead to insufficient sulfur resistance of the inner coating in actual application.

[0004] The existing patent provides a tin-chromium composite plated steel plate applicable to eight-treasure rice porridge cans. Through the steps of annealing, flattening, pre-plating, plating and multiple passivation, a composite plated steel plate with good corrosion resistance, weldability and finishing performance is obtained. However, due to the brittle texture of the composite coating, the finishing performance will decrease after large deformation, and the inner coating will produce toxic sulfides at high temperature when in contact with high-protein content, which cannot meet the performance requirement of high-end eight-treasure rice porridge can tin-plated plate. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to overcome the defects of insufficient sulfur resistance of the existing tin-plated plate, and to provide a high-sulfur-resistance tin-plated plate and a preparation method and application thereof.

[0006] To this end, the present application provides the following technical solution:

[0007] The first aspect of the present application provides a high-sulfur-resistance tin-plated plate, wherein the high-sulfur-resistance tin-plated plate comprises a first passivation layer, a first tin-plated layer, a first multi-element alloy layer, a tin-plated substrate layer, a second multi-element alloy layer, a second tin-plated layer and a second passivation layer arranged in sequence.

[0008] The surface of the first passivation layer away from the first tin-plated layer is an inner coating surface;

[0009] The second passivation layer is an outer coating surface away from the surface of the second tin-plated layer;

[0010] The arithmetic average roughness of the inner coating surface is 0.4-0.5 μm, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3.

[0011] The arithmetic average roughness of the outer coating surface is 0.6-0.7 μm, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3.

[0012] The first and second multi-element alloy layers each independently comprise gallium.

[0013] The arithmetic average roughness of the inner coating surface is 0.4-0.5 μm, for example, the arithmetic average roughness of the inner coating surface can be 0.42 μm, 0.44 μm, 0.46 μm, 0.48 μm, 0.5 μm, or within a range defined by any of the above values; the profile skewness is 0-0.3, for example, the profile skewness can be 0, 0.005, 0.01, 0.05, 0.15, 0.2, 0.25, 0.3, or within a range defined by any of the above values; and the profile kurtosis is 2.5-3, for example, the profile kurtosis can be 2.5, 2.6, 2.7, 2.8, 2.9, 3, or within a range defined by any of the above values.

[0014] The arithmetic average roughness of the outer coating surface is 0.6-0.7 μm, for example, the arithmetic average roughness of the outer coating surface can be 0.6 μm, 0.62 μm, 0.64 μm, 0.68 μm, 0.7 μm, or within a range defined by any of the above values; the profile skewness is 0-0.3, for example, the profile skewness can be 0, 0.1, 0.2, 0.3, or within a range defined by any of the above values; and the profile kurtosis is 2.5-3, for example, the profile kurtosis can be 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, or within a range defined by any of the above values.

[0015] In the present application, the arithmetic average roughness (Ra), the profile skewness (Rsk), and the profile kurtosis (Rku) are tested by using a contact surface roughness meter.

[0016] In an alternative embodiment, the arithmetic average roughness of the inner coating surface is 0.42-0.48 μm, the profile skewness is 0.05-0.1, and the profile kurtosis is 2.7-2.8.

[0017] In an alternative embodiment, the arithmetic average roughness of the outer coating surface is 0.62-0.66 μm, the profile skewness is 0-0.2, and the profile kurtosis is 2.6-3.

[0018] In an alternative embodiment, the first multi-component alloy layer, the second multi-component alloy layer each independently comprises 0.05-0.1 g / m2of gallium; as an example, the first multi-component alloy layer, the second multi-component alloy layer each independently comprises 0.05 g / m2, 0.06 g / m2, 0.07 g / m2, 0.08 g / m2, 0.09 g / m2, 0.1 g / m2of gallium, or within a range consisting of any of the above values. 2 2 2 2 2 2

[0019] In an alternative embodiment, the first multi-component alloy layer, the second multi-component alloy layer each independently comprises 0.4-0.5 g / m2of tin; as an example, the first multi-component alloy layer, the second multi-component alloy layer each independently comprises 0.4 g / m2, 0.42 g / m2, 0.44 g / m2, 0.46 g / m2, 0.48 g / m2, 0.5 g / m2of tin, or within a range consisting of any of the above values. 2 2 2 2 2 2 2

[0020] The second aspect of the present application protects a method for preparing the aforementioned high-sulfur-resistance tinplate, wherein the method comprises the following steps: annealing, skin-passing, surface activation, flash plating of gallium, electroplating, fluxing, quenching, passivation, oiling, and packaging of the tinplate; the tinplate is skin-passed by two stands of work rolls, the arithmetic average roughness, profile skewness, and profile kurtosis of the upper and lower work rolls of the first stand are the same, wherein the arithmetic average roughness is 0.3-0.5 μm, the profile skewness is -0.5 to -0.3, and the profile kurtosis is 2.5-3; the arithmetic average roughness of the upper work roll of the second stand is 0.8-1.0 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.5-3; the arithmetic average roughness of the lower work roll of the second stand is 0.5-0.7 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.5-3.

[0021] ​​​​​​​​​​​​​In the present application, the surface activation includes alkali washing and acid washing; the alkali washing adopts a mixed solution of NaOH and Na2CO3, the concentration of NaOH is 35-40 g / L, the concentration of Na2CO3 is 10-20 g / L, the amount of the mixed solution is not limited, which can completely immerse the flattened tinned substrate, the time of alkali washing is 1-1.5 s. Sodium hydroxide has strong saponification ability as a strong alkali, which can saponify and remove oil, and has certain emulsification ability. Sodium carbonate has a buffering effect on pH value, which helps to maintain the alkalinity of the solution, thereby stabilizing the oil removal capacity and avoiding unstable oil removal effect caused by pH fluctuation of the solution. The acid washing is divided into two steps, the first step of acid washing is chemical acid washing, which adopts H2SO4 solution with a concentration of 60-70 g / L, the amount of H2SO4 solution is not limited, which can completely immerse the tinned substrate after alkali washing, the time of acid washing is 1-1.5 s; the second step of acid washing is electrochemical acid washing, which adopts H2SO4 solution with a concentration of 20-30 g / L, the amount of H2SO4 solution is not limited, which can completely immerse the tinned substrate after the first step of acid washing, the current density is 12-15 A / dm 2 , the time of acid washing is 1-1.2 s. Compared with one-step acid washing, the first acid washing adopts H2SO4 solution with higher concentration, which utilizes chemical dissolution to quickly remove the thick oxide film on the metal surface; the second acid washing uses H2SO4 solution with low concentration and current, which removes the residual thin oxide film and micro burrs through anodic dissolution effect in the electrolysis process, to realize surface flattening.

[0022] In an alternative embodiment, two racks of work rolls are used to flatten the tinned substrate, the arithmetic average roughness of the upper and lower work rolls in one rack is 0.3-0.5 μm, the profile skewness is -0.5 to -0.3, and the profile kurtosis is 2.6-2.8; the arithmetic average roughness of the upper work roll in the second rack is 0.85-0.95 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.6-3; the arithmetic average roughness Ra of the lower work roll in the second rack is 0.55-0.65 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.6-2.8.

[0023] In an alternative embodiment, the conditions of flash plating gallium include: the pH value of the gallium-containing solution is 11-13, the concentration of Ga 3+ is 45-50 g / L, and the amount of flash plating gallium per unit area is 0.05-0.1 g / m 2 .

[0024] In the present application, the gallium-containing solution includes gallium-containing compounds, pH adjusters and water, without limitation on specific types and amounts, as long as the specific gallium ion content and pH value can be met, typically and non-limitingly, the gallium-containing compounds include at least one of gallium sulfate, gallium chloride and gallium nitrate, and the gallium sulfate can be selected; the pH adjuster includes a mixed solution of citric acid (C6H8O7) and sodium citrate (C6H5Na3O7) with a mass ratio of 1:(2-3), and sodium hydroxide (NaOH) is added to control the pH value of the gallium-containing solution to be 11-13. After flash plating, the plated tin substrate is soaked in desalted water, the conductivity of the desalted water is 0-5 μS / cm, the amount of the desalted water is not limited, as long as the plated tin substrate can be completely immersed, and the soaking time is 0.5-1.0 s. The flash plating of gallium lays a foundation for the preparation of subsequent multinary alloy layers, and the composition of the flash plating gallium solution and the pH value are accurately controlled, so that the flash plating efficiency and quality can be significantly improved, thereby optimizing the performance of the subsequent multinary alloy coating.

[0025] In the present application, when the conventional tin-plated plate is fluxed, tin flows at the interface with the iron base to make the coating more uniform, and tin-iron alloy is formed at the interface to enhance the overall corrosion resistance. The addition of flash plating of gallium can utilize the characteristics of low melting point / high flowability of gallium to improve the leveling effect of the tin coating, form a multinary alloy layer, reduce the overall porosity, and improve the corrosion resistance and coating uniformity.

[0026] In an alternative embodiment, the thickness of the tin-plated substrate layer is 0.18-0.20 mm; in terms of mass percentage of chemical composition, the tin-plated substrate layer includes C: 0.045-0.075%; Si: 0-0.002%; Mn: 0.15-0.20%; P: 0-0.010%; S: 0-0.01%; Cr: 0-0.01%; Ni: 0-0.1%; Cu: 0-0.1%; Al: 0.03-0.05%; and the balance is iron and unavoidable impurity elements. By controlling the internal composition, the initial mechanical properties of the tin-plated substrate layer are ensured to cope with subsequent large deformation processing.

[0027] In an alternative embodiment, the annealing conditions include: the annealing temperature is 635-650℃, the time is 25-35 s, the dew point of annealing is -40 to -20℃, and the annealing atmosphere is a mixed gas of N2 and H2, the concentration of H2 is 15-20% by volume, the concentration of N2 is 80-90%, the concentration of O2 is <5ppmv, and the concentration of other impurity gases is <1ppmv.

[0028] In an alternative embodiment, the electroplating uses an MSA (methyl sulfonic acid) electroplating solution, wherein the concentration of MSA is 120-130 g / L, the concentration of free acid is 25-42 mL / L, the concentration of Sn 2+The concentration of ions is 25-40 g / L, Fe 2+ The concentration of ions is 0-50 ppm.

[0029] In the present application, during electroplating, the anode is a conventional soluble pure tin anode in the art, typically and non-limitatively, the tin content in the pure tin anode is 99.99%-100%, and the lead content is less than 20 ppm. Strict control of the plating solution composition can effectively improve the tin plating efficiency, and ensure that the plating layer is dense, uniform and has low porosity. At the same time, optimization of the tin anode control can further improve the plating layer quality and enhance the environmental protection performance.

[0030] In an alternative embodiment, the electroplating conditions include that the temperature of the electroplating solution is 42-48°C, the current density is 15-25 A / dm 2 .

[0031] In the present application, the multi-element alloy layer is prepared by high-frequency pure inductive softening, and the softening is immediately quenched. The softening is carried out under inert gas protection, typically and non-limitatively, the N2 concentration is 98-100%; the quenching uses desalted water, and the conductivity of the desalted water is 0-5 μS / cm. By softening, the surface temperature reaches above the melting point of tin and gallium, which promotes the formation of a multi-element alloy layer with the tin substrate layer. Compared with conventional tin-iron alloys, the flowability of the mixture of tin, gallium and iron is better, the toughness and plasticity of the prepared film layer are strong, and the softening atmosphere can reduce the content of tin oxides in the tin plating layer, thereby further improving the plasticity of each film layer and avoiding the generation of micro-cracks in the high-sulfur-resistant tin-plated plate under large deformation.

[0032] In an alternative embodiment, the softening conditions include that the softening temperature is 235-270°C, and the softening time is 0.8-1.8 s.

[0033] In an alternative embodiment, the quenching conditions include that the quenching temperature is 80-82°C, and the quenching time is 0.8-1.0 s.

[0034] In the present application, the passivation treatment adopts a composite passivation process, including chromate passivation and chromic acid passivation. First, chromate passivation is carried out, the chromate passivation solution is a conventional solution in the art, typically and non-limitatively, an aqueous solution of Na2Cr2O7 with a concentration of 22-28 g / L is used for passivation, and an aqueous solution of CrO3 with a concentration of 200-250 g / L is used to control the pH value to 4-4.2, the passivation temperature is 40-42°C, the electric quantity of passivation is 0.6-0.7 C / dm 2 , the current density of passivation is 6-8 A / dm 2 , and the passivation amount is 2-3 mg / m 2; then chromium passivation is carried out, the chromium passivation solution is a conventional solution in the art, typically and non-limitatively, a CrO3 solution with a concentration of 65-75 g / L is used for passivation, a H2SO4 solution with a concentration of 0.65-0.75 g / L is added, the mass ratio of CrO3 and sulfate is 100-110:1; the passivation temperature is 45-50°C, the electric quantity for passivation is 4.0-4.5 C / dm 2 , the passivation current density is 50-55 A / dm 2 , the passivation amount is 15-20 mg / m 2 , calculated based on CrO3.

[0035] In the present application, the oil coating method is a conventional method in the art, typically and non-limitatively, vertical electrostatic oil coating is used, the reagent is DOS-A oil (dios-2-ethylhexyl adipate), the oil coating amount is 2.5-3.5 mg / m2, calculated based on DOS-A oil, the oil temperature is 40-45°C, and the voltage is 18-20 kV. By controlling the type and amount of DOS oil, the surface wettability of the tin-plated plate is improved.

[0036] In the present application, the packaging is carried out within 30 min-2 h after oil coating.

[0037] The third aspect of the present application protects the use of the aforementioned high-sulfur-resistant tin-plated plate in the field of protein-containing food packaging.

[0038] In the present application, the protein-containing food packaging is conventional in the art, typically and non-limitatively, eight-treasure rice pudding cans are processed into eight-treasure rice pudding cans, which include: the inner coating uses epoxy phenolic or epoxy amino coating, and a one-coat-one-bake process (coating once and baking once) is used, the coating amount is 7-8 g / m 2 , the baking temperature is 185-200°C, and the time is 15-20 min; the coating on the outer surface is not specified and can be coated according to actual product requirements, usually including primer, white varnish, and ink printing, wherein the film coating amount of white varnish is 10-12 g / m 2 , the baking temperature is 180-190°C, and the baking time is 12-18 min.

[0039] The canning process is cutting, rounding, welding, re-coating, necking (expanding, expanding, and expanding), flanging, sealing, drying, filling, bottom sealing, rotary sterilization, and finished product, wherein rounding, necking, flanging, sealing, rotary sterilization, and subsequent transportation process all cause friction and deformation to the coated tin-plated plate.

[0040] The technical solution of the present application has the following advantages:

[0041] 1. The application provides a high-sulfur-resistant tin-plated sheet, wherein the high-sulfur-resistant tin-plated sheet comprises a first passivation layer, a first tin-plated layer, a first multi-element alloy layer, a tin-plated substrate layer, a second multi-element alloy layer, a second tin-plated layer, and a second passivation layer arranged in sequence; the surface of the first passivation layer away from the first tin-plated layer is an inner coating surface; the surface of the second passivation layer away from the second tin-plated layer is an outer coating surface; the arithmetic average roughness of the inner coating surface is 0.4-0.5 μm, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3; the arithmetic average roughness of the outer coating surface is 0.6-0.7 μm, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3; the first multi-element alloy layer and the second multi-element alloy layer each independently comprise gallium; the high-sulfur-resistant tin-plated sheet of the application has strong bonding force between the film layers, good toughness, and is not prone to cracking or falling off, can cope with various deformations in the processing process, and has excellent adhesion of the outer coating surface, can avoid the generation of micro-cracks during deformation processing, and can meet the performance requirements of high-end food and beverage packaging materials. The specific inner coating surface parameters provide a uniform, dense, and defect-free surface microstructure, which can avoid pores caused by "incomplete coverage, stress concentration, and deep valley dead angle" when being coated as a coating substrate; at the same time, the sulfur-resistant coating has good fluidity, can uniformly coat the inner coating surface, has good uniformity and adhesion of each layer, forms a continuous and sulfur-resistant barrier, hinders the penetration of sulfur ions through the film layer pores to the base layer, and improves the sulfur resistance; the specific outer coating surface parameters can enable the outer coating surface to fully contact the coating material, and when the high-sulfur-resistant tin-plated sheet is processed into a eight-treasure congee can, micro-cracks can be avoided, and even in the case of large deformation, the performance is still good. The first multi-element alloy layer and the second multi-element alloy layer comprise gallium, have excellent chemical stability, effectively block the penetration of sulfur ions, avoid the formation of black spots, exhibit excellent leveling and plasticity, have extremely low porosity, and have strong oxidation resistance, and are very suitable for deformation processing.

[0042] 2. The specific parameters of the inner coating surface and the outer coating surface of the application can further optimize the synergistic effect of sulfur resistance and mechanical properties; at the same time, by precisely controlling the surface microtopography, directional adaptation to different functional requirements is realized, and the requirements of protein-containing food packaging in complex processing environments are met.

[0043] 3. The application provides a high-sulfur-resistant tin-plated plate preparation method, wherein the preparation method comprises the following steps: annealing, flattening, surface activation, flash plating of gallium, electroplating, softening, quenching, passivation, oiling and packaging of the tin-plated substrate; the tin-plated substrate is flattened by two racks of work rolls, the arithmetic average roughness, profile skewness and profile kurtosis of the upper and lower work rolls of one rack are the same, wherein the arithmetic average roughness is 0.3-0.5 μm, the profile skewness is -0.5 to -0.3, and the profile kurtosis is 2.5-3; the arithmetic average roughness of the upper work roll of the second rack is 0.8-1.0 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.5-3; the arithmetic average roughness of the lower work roll of the second rack is 0.5-0.7 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.5-3; the profile parameters of the two sides of the flattened plate are different, which determines the basic properties of the plate and is transferred to the finally prepared high-sulfur-resistant tin-plated plate, so as to meet the expected standards of the inner coating surface and the outer coating surface; the specific parameters of the surface treated by the lower work roll of the second rack provide an ideal substrate for the preparation of the subsequent coating, the treatment enables the newly deposited coating to exhibit excellent flow performance, completely covers the inside, so as to obtain a dense film layer with uniform structure and low porosity, good adhesion between layers, the inner coating surface after the treatment of the lower work roll of the second rack forms a continuous physical barrier, hinders the penetration of sulfur ions through the film layer pores to the base layer, and has excellent sulfur resistance; the surface treated by the upper work roll of the second rack is the outer coating surface, has excellent adhesion, and can avoid the generation of microcracks, and can still maintain good mechanical properties even in the case of large deformation.

[0044] 4. The annealing treatment can improve the processability of the tin-plated substrate, the internal composition of the tin-plated substrate is controlled, the hardness of the tin-plated plate is controlled in a specified range, and the tin-plated plate has certain toughness and plasticity; during subsequent processing, even if the material deforms, the substrate and the film layer can still maintain close adhesion, have excellent adhesion, and have good sulfur resistance. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0046] Figure 1 is a schematic diagram of the high-sulfur-resistant tin-plated plate of Example 1;

[0047] The figure legend: 1-first passivation layer; 2-first tin-plated layer; 3-first multi-element alloy layer; 4-tin-plated substrate layer; 5-second multi-element alloy layer; 6-second tin-plated layer; 7-second passivation layer. DETAILED DESCRIPTION

[0048] The following examples are provided to better enable those skilled in the art to further understand the application and are not intended to limit the scope of the application in any way. The contents and scope of the present application are not limited to the best mode for carrying out the application, and any product that is the same or similar to the present application obtained by anyone under the guidance of the present application or by combining the present application with other prior art features falls within the scope of the present application.

[0049] The experimental procedures or conditions not specified in the examples can be carried out according to the conventional experimental procedures described in the literature in the art. The reagents or instruments not specified by the manufacturer are conventional reagent products that can be obtained commercially.

[0050] In the present application, the electroplating anode is a tin anode, the tin content is 99.995%, and the lead content is 18 ppm.

[0051] Example 1

[0052] The present embodiment provides a high-sulfur-resistant tin-plated sheet, as shown in the schematic diagram Figure 1 The preparation method comprises the following steps:

[0053] (1) The thickness of the tin-plated substrate layer is 0.185 mm, and the tin-plated substrate layer comprises, in terms of mass percentage of chemical composition, 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%; and the rest is iron and inevitable impurity elements;

[0054] (2) Annealing: the annealing temperature is 645°C, the annealing time is 25 s, the annealing dew point is -30°C, and the annealing atmosphere is a mixed gas of N2 and H2, the concentration of H2 is 18% and the concentration of N2 is 82% by mass of the mixed gas, the concentration of impurity gas is 0.8 ppmv, and the concentration of O2 is 1 ppmv;

[0055] (3) Leveling: the arithmetic average roughness of the upper and lower work rolls of the first rack is 0.48 μm, the profile skewness is -0.4, and the profile kurtosis is 2.6; the arithmetic average roughness of the upper work roll of the second rack is 0.92 μm, the profile skewness is -0.1, and the profile kurtosis is 2.8, the arithmetic average roughness of the lower work roll of the second rack is 0.68 μm, the profile skewness is -0.1, and the profile kurtosis is 2.7;

[0056] (4) surface activation: the alkali washing solution is a mixed solution of NaOH and Na2CO3, the concentration of NaOH is 36 g / L and the concentration of Na2CO3 is 18 g / L in the mixed solution, the mixed solution completely covers the tinned substrate after being flattened, the time for alkali washing is 1.1 s; the acid washing is carried out in two steps, the first step is chemical acid washing, a H2SO4 solution with a concentration of 68 g / L is used, the amount of H2SO4 solution completely covers the tinned substrate after alkali washing, the time for acid washing is 1.3 s, the second step is electrochemical acid washing, a H2SO4 solution with a concentration of 28 g / L is used, the amount of H2SO4 solution completely covers the tinned substrate after the first step of acid washing, the current density is 14 A / dm 2 , the time for acid washing is 1.15 s;

[0057] (5) flash plating of gallium, the gallium-containing solution is a mixed solution of gallium sulfate, sodium hydroxide and sodium citrate, the concentration of Ga 3+ is 46 g / L in terms of the mass of the gallium-containing solution; the buffer substance is sodium citrate with a mass ratio of 1:2.5 to sodium hydroxide, which is used to control the pH value of the plating solution to be 12, the amount of the buffer substance is added according to the actual situation to maintain the gallium in the plating solution from being precipitated, the amount of gallium used for flash plating is 0.06 g / m 2 in terms of unit area, the tinned substrate after flash plating is completely immersed in desalted water (the conductivity is 3 μS / cm) for 0.8 s;

[0058] (6) electroplating: the electroplating solution is MSA plating solution, the concentration of MSA is 125 g / L, the concentration of free acid is 30 mL / L, the concentration of Sn 2+ ion is 30 g / L, the concentration of Fe 2+ ion is 24 ppm, the temperature of the electroplating solution is 44 °C, and the current density is 24.5 A / dm 2 ;

[0059] (7) soft melting: high-frequency pure inductive soft melting is used, the temperature of soft melting is 252 °C, the concentration of N2 in the atmosphere of soft melting is 99%, and the time for soft melting is 1.1 s to form a multicomponent alloy layer;

[0060] (8) water quenching: the soft melting is immediately followed by water quenching, the temperature of water quenching is 82 °C, the time for water quenching is 0.9 s, and the water quenching solution is desalted water with a conductivity of 3 μS / cm;

[0061] (9) passivation: the passivation treatment adopts a composite passivation process, including chromate passivation and chromic acid passivation; for chromate passivation, a Na2Cr2O7 solution with a concentration of 25 g / L is used for passivation, and a CrO3 aqueous solution with a concentration of 240 g / L is used to adjust the pH value to 4.1, the temperature for passivation is 41 °C, the electric quantity for passivation is 0.65 C / dm 2 , and the current density for passivation is 6.8 A / dm2 The passivation amount is 2.5 mg / m 2 The chromium acid passivation is performed again, and a CrO3 solution with a concentration of 70 g / L is used for passivation, an H2SO4 solution with a concentration of 0.7 g / L is added, the mass ratio of CrO3 and sulfate is 100:1, the passivation temperature is 48 °C, and the electric quantity for passivation is 4.2 C / dm 2 The passivation current density is 52 A / dm 2 The passivation amount is 18 mg / m 2 ;

[0062] (10) Oil coating: vertical electrostatic oil coating is adopted, the reagent is DOS-A oil, the oil coating amount is 2.8 mg / m 2 , the oil temperature is 42 °C, and the voltage is 19 kV;

[0063] (11) Packaging: the sealed packaging is performed 30 min after the oil coating.

[0064] Example 2

[0065] The embodiment provides a high-sulfur-resistance tin-plated plate, and a preparation method thereof.

[0066] (1) The thickness of the tin-plated base plate layer is 0.19 mm, and the tin-plated base plate layer comprises, in terms of mass percentage of chemical components, C: 0.048%; Si: 0.001%; Mn: 0.16%; P: 0.009%; S: 0.006%; Cr: 0.007%; Ni: 0.06%; Cu: 0.05%; Al: 0.035%; and the rest is iron and inevitable impurity elements;

[0067] (2) Annealing: the annealing temperature is 648 °C, the annealing time is 25 s, the dew point of annealing is -35 °C, the annealing atmosphere is a mixed gas of N2 and H2, the concentration of H2 is 19% and the concentration of N2 is 81% in terms of mass of the mixed gas, the impurity gas concentration is 0.5 ppmv, and the O2 content is 2 ppmv;

[0068] (3) Smoothing: the arithmetic average roughness of the upper and lower work rolls of the first rack is 0.45 μm, the profile skewness is -0.4, and the profile kurtosis is 2.8; the arithmetic average roughness of the upper work roll of the second rack is 0.95 μm, the profile skewness is -0.05, and the profile kurtosis is 2.9; the arithmetic average roughness of the lower work roll of the second rack is 0.68 μm, the profile skewness is -0.1, and the profile kurtosis is 2.7;

[0069] (4) surface activation: the alkali washing solution is a mixed solution of NaOH and Na2CO3, the concentration of NaOH is 38 g / L and the concentration of Na2CO3 is 17 g / L in the mixed solution, the tinned substrate is completely immersed in the mixed solution, the alkali washing time is 1.5 s; the acid washing is divided into two steps, the first step is chemical acid washing, a H2SO4 solution with a concentration of 62 g / L is used, the amount of the H2SO4 solution is enough to immerse the tinned substrate after alkali washing, the acid washing time is 1.2 s, the second step is electrochemical acid washing, a H2SO4 solution with a concentration of 25 g / L is used, the amount of the H2SO4 solution is enough to immerse the tinned substrate after the first step acid washing, the current density is 13.5 A / dm 2 , the acid washing time is 1.1 s;

[0070] (5) flash plating of gallium, the gallium-containing solution is a mixed solution of gallium sulfate, sodium hydroxide and sodium citrate, the concentration of Ga 3+ is 48 g / L in the gallium-containing solution, the buffer substance is sodium citrate with a mass ratio of 1:3 to citric acid and sodium hydroxide together to control the pH value of the plating solution to be 12.8, the amount of the buffer substance is added according to the actual situation to maintain the gallium in the plating solution from precipitating, the amount of the gallium used for flash plating is 0.08 g / m 2 per unit area, the tinned substrate is completely immersed in the desalted water (the conductivity is 3 μS / cm) after flash plating, the soaking time is 0.9 s;

[0071] (6) electroplating: the electroplating solution is MSA plating solution, the concentration of MSA is 128 g / L, the concentration of free acid is 30 mL / L, the concentration of Sn 2+ ion is 30 g / L, the concentration of Fe 2+ ion is 28 ppm, the temperature of the electroplating solution is 43 °C, and the current density is 24 A / dm 2 ;

[0072] (7) soft melting: high-frequency pure inductive soft melting is used, the soft melting temperature is 255 °C, the concentration of N2 in the soft melting atmosphere is 99%, and the soft melting time is 1.0 s to form a multielement alloy layer;

[0073] (8) water quenching: the soft melting is immediately followed by water quenching, the water quenching temperature is 81 °C, the water quenching time is 0.9 s, and the water quenching solution is desalted water with a conductivity of 3 μS / cm;

[0074] (9) passivation: the passivation treatment adopts a composite passivation process including chromate passivation and chromic acid passivation; the chromate passivation uses a Na2Cr2O7 solution with a concentration of 24 g / L for passivation, and a CrO3 aqueous solution with a concentration of 240 g / L is used to adjust the pH value to 4.1, the passivation temperature is 41 °C, the electric quantity of passivation is 0.65 C / dm 2 , and the current density of passivation is 6.6 A / dm2 The passivation amount is 2.5 mg / m 2 The chromium acid passivation is performed again using a CrO3 solution having a concentration of 70 g / L, and a H2SO4 solution having a concentration of 0.7 g / L is added, the mass ratio of CrO3 to sulfate is 100:1, the passivation temperature is 48 °C, and the electric quantity of passivation is 4.2 C / dm 2 The current density of passivation is 52 A / dm 2 The passivation amount is 16 mg / m 2 ;

[0075] (10) Oil coating: vertical electrostatic oil coating is used, the reagent is DOS-A oil, the oil coating amount is 2.5 mg / m 2 , the oil temperature is 42 °C, and the voltage is 19.5 kV;

[0076] (11) Packaging: the sealed packaging is performed within 1 h after the oil coating.

[0077] Example 3

[0078] The present example provides a high sulfur resistance tin-plated steel sheet, and the preparation method comprises the following steps:

[0079] According to the manner of Example 1, the difference is that in step (3), the smoothing: the arithmetic average roughness of the upper work rolls of the first rack is 0.35 μm, the profile skewness is -0.4, and the profile kurtosis is 2.8; the arithmetic average roughness of the upper work rolls of the second rack is 0.82 μm, the profile skewness is -0.1, and the profile kurtosis is 2.5; the arithmetic average roughness of the lower work rolls of the second rack is 0.7 μm, the profile skewness is -0.18, and the profile kurtosis is 2.65.

[0080] Comparative Example 1

[0081] The present comparative example provides a high sulfur resistance tin-plated steel sheet, and the preparation method comprises the following steps:

[0082] According to the manner of Example 3, the difference is that there is no flash plating of gallium, and the surface is activated directly before the electroplating step.

[0083] Comparative Example 2

[0084] The present comparative example provides a high sulfur resistance tin-plated steel sheet, and the preparation method comprises the following steps:

[0085] In the same manner as in Example 1, except that in step (3), the arithmetic average roughness of the upper work rolls of the first and second stands was 0.48 μm, the profile skewness was -0.4, and the profile kurtosis was 2.6; the arithmetic average roughness of the upper work roll of the second stand was 0.92 μm, the profile skewness was -0.1, and the profile kurtosis was 2.8; and the arithmetic average roughness of the lower work roll of the second stand was 0.98 μm, the profile skewness was -0.15, and the profile kurtosis was 3.0.

[0086] Test Example

[0087] The arithmetic average roughness, profile skewness, and profile kurtosis of the high-sulfur-resistance tinplate after packaging were tested using a contact surface roughness meter.

[0088] The specific test data are shown in Table 1.

[0089] Table 1: Test results of the arithmetic average roughness, profile skewness, and profile kurtosis of the inner coating and the outer coating

[0090]

[0091] The gallium content and the tin content of the high-sulfur-resistance tinplate were tested according to the Coulomb method, and the specific test results are shown in Table 2.

[0092] Table 2: Gallium content of the first and second multielement alloy layers and tin content of the first and second multielement alloy layers

[0093]

[0094] The inner coating of the high-sulfur-resistance tinplate after unpackaging was coated with epoxy phenolic at a coating amount of 7 g / m 2 , a baking temperature of 190 °C, and a baking time of 15 min; and the outer coating of the high-sulfur-resistance tinplate after packaging was coated with white lacquer at a coating amount of 10 g / m 2 , a baking temperature of 180 °C, and a baking time of 15 min.

[0095] The adhesion grade of the coated high-sulfur-resistance tinplate was tested according to the method of GB / T41899-2022, and the test results are shown in Table 3.

[0096] Table 3: Test results of the adhesion grade of the inner coating and the outer coating

[0097]

[0098] Sulfur resistance grade: The number of sulfurization spots per square decimeter was recorded according to the method of GB / T41899-2022, and the average value of 10 tests was taken.

[0099] Salt resistance grade: According to GB / T41899-2022 method, the number of salt corrosion spots per square decimeter was recorded, and the test was repeated 10 times to take the average value;

[0100] The dyne value of the high sulfur resistance performance tinplate after packaging was tested by a dyne pen;

[0101] The test results are shown in Table 4;

[0102] Table 4 Test results of sulfurization spots, salt corrosion spots and dyne value of inner coating and outer coating

[0103]

[0104] The high sulfur resistance performance tinplate has strong bonding force between each film layer, good toughness, is not easy to crack or fall off, can cope with various deformations in the processing process, and has excellent sulfur resistance performance.

[0105] Obviously, the above examples are only examples for clearly illustrating, but not limitation to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A tin-plated sheet with high sulfur resistance, characterized in that, The high sulfur resistance tin-plated plate includes a first passivation layer, a first tin plating layer, a first multi-element alloy layer, a tin-plated substrate layer, a second multi-element alloy layer, a second tin plating layer, and a second passivation layer arranged sequentially. The surface of the first passivation layer that is far from the first tin plating layer is the inner coating surface; The surface of the second passivation layer that is away from the second tin plating layer is the outer coating surface; The arithmetic mean roughness of the inner coating surface is 0.4-0.5 μm, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3. The arithmetic mean roughness of the outer coating surface is 0.6-0.7 μm, the profile skewness is 0-0.3, and the profile kurtosis is 2.5-3. The first multi-element alloy layer and the second multi-element alloy layer each independently include gallium; The preparation method of high sulfur resistance tin-plated board includes the following steps: annealing, leveling, surface activation, gallium flash plating, electroplating, remelting, water quenching, passivation, oiling, and packaging of the tin-plated substrate.

2. The high sulfur resistance tin-plated sheet according to claim 1, characterized in that, The arithmetic mean roughness of the inner coating surface is 0.42-0.48 μm, the profile skewness is 0.05-0.1, and the profile kurtosis is 2.7-2.

8. The arithmetic mean roughness of the outer coating surface is 0.62-0.66 μm, the profile skewness is 0-0.2, and the profile kurtosis is 2.6-3.

3. The high sulfur resistance tin-plated sheet according to claim 1, characterized in that, The first multi-component alloy layer and the second multi-component alloy layer each independently comprise 0.05-0.1 g / m2 2 of gallium, measured per unit area. And / or, on a unit area basis, the first multi-element alloy layer and the second multi-element alloy layer each independently comprise 0.4-0.5 g / m². 2 Tin.

4. A method for preparing a high sulfur-resistant tin-plated sheet according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: annealing, flattening, surface activation, flash gallium plating, electroplating, soft melting, water quenching, passivation, oiling, and packaging of the tin-plated substrate; A two-frame work roller is used to flatten the tin-plated substrate. The arithmetic mean roughness, profile skewness, and profile kurtosis of the upper and lower work rollers of one frame are the same. The arithmetic mean roughness is 0.3-0.5μm, the profile skewness is -0.5 to -0.3, and the profile kurtosis is 2.5-3. The arithmetic mean roughness of the working rolls on the second stand is 0.8-1.0 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.5-3. The arithmetic mean roughness of the working rolls on the second stand is 0.5-0.7 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.5-3.

5. The preparation method according to claim 4, characterized in that, The tin-plated substrate is flattened using two-frame work rollers. The arithmetic mean roughness of the upper and lower work rollers of one frame is 0.3-0.5μm, the profile skewness is -0.5 to -0.3, and the profile kurtosis is 2.6-2.

8. The arithmetic mean roughness of the working rolls on the second stand is 0.85-0.95 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.6-3. The arithmetic mean roughness Ra of the working rolls on the second stand is 0.55-0.65 μm, the profile skewness is -0.2 to 0, and the profile kurtosis is 2.6-2.

8.

6. The preparation method according to claim 4 or 5, characterized in that, The conditions for the flash gallium plating include: a gallium-containing solution with a pH of 11-13, and, based on the mass of the gallium-containing solution, Ga... 3+ The concentration is 45-50 g / L, and the amount of gallium used in flash plating is 0.05-0.1 g / m². 2 .

7. The preparation method according to claim 4 or 5, characterized in that, The thickness of the tin-plated substrate layer is 0.18-0.20 mm; the composition of the tin-plated substrate layer, based on the mass percentage of chemical components, is C: 0.045-0.075%; Si: 0-0.002%; Mn: 0.15-0.20%; P: 0-0.010%. S: 0-0.01%; Cr: 0-0.01%; Ni: 0-0.1%; Cu: 0-0.1%; Al: 0.03-0.05%; the remainder is iron and unavoidable impurity elements; And / or, the annealing conditions include: an annealing temperature of 635-650℃, a annealing time of 25-35s, an annealing dew point of -40 to -20℃, an annealing atmosphere of a mixture of N2 and H2, wherein the concentration of H2 is 15-20% by volume, the concentration of N2 is 80-90%, the concentration of O2 is <5ppmv, and the concentration of other impurity gases is <1ppmv.

8. The preparation method according to claim 4 or 5, characterized in that, The electroplating uses a methanesulfonic acid electroplating solution, wherein the concentration of methanesulfonic acid is 120-130 g / L, the concentration of free acid is 25-42 mL / L, and the Sn in the solution... 2+ The concentration of ions is 25-40 g / L, Fe 2+ The concentration of ions is 0-50 ppm; And / or, the electroplating conditions include: a plating solution temperature of 42-48°C and a current density of 15-25 A / dm³. 2 .

9. The preparation method according to claim 4 or 5, characterized in that, The conditions for softening include: a softening temperature of 235-270℃ and a softening time of 0.8-1.8s; And / or, the quenching conditions include: a quenching water temperature of 80-82℃ and a quenching time of 0.8-1.0s.

10. The application of a high sulfur-resistant tinplate as described in any one of claims 1-3 in the field of protein-containing food packaging.

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