A passivation film on tin-plated layer surface, tin-plated plate and passivation method for tin-plated plate surface

Abstract

The present invention provides a passivation film on the surface of a tin plating layer, a tinplate, and a passivation method for the surface of a tinplate, belonging to the technical field of metal surface treatment. The passivation film on the surface of the tin plating layer includes a first passivation layer and a second passivation layer located on the surface of the first passivation layer; the first passivation layer is a chromium-containing passivation film layer, and the Cr content in the chromium-containing passivation film layer is 3-6 mg / m 2 ; the second passivation layer is a Ti-Zr-based passivation film layer, and the Ti element in the Ti-Zr-based passivation film exists in the form of TiO2. The produced tinplate has good adhesion, sulfur resistance, acid resistance, salt resistance and other properties, as well as excellent corrosion resistance and salt spray resistance. At the same time, this method can adapt to tin plating layers of 0.5-11.2 g / m 2 , and the production line speed can meet the technical requirements of 500 m / min.

Description

Technical Field

[0001] The present application relates to the technical field of metal surface treatment, and in particular to a passivation film on the surface of a tin-plated layer, a tin-plated plate, and a passivation method for the surface of a tin-plated plate. Background Art

[0002] Tinplate is a cold-rolled low-carbon steel sheet or strip coated with tin on both sides by electroplating. In order to improve the performance of tinplate, it is usually necessary to passivate the surface of the tinplate. The existing passivation treatment forms a single passivation film, which has a single function and cannot meet the use requirements of complex environments.

[0003] At present, there is no report on the research of tinplate with a two-layer structure passivation film. Summary of the invention

[0004] The embodiments of the present application provide a tin-plated surface passivation film, a tin-plated plate, and a passivation method for the surface of a tin-plated plate to solve the technical problem that the existing tin-plated plate surface is passivated to form a single-structure passivation film with a single function and cannot meet the use requirements of complex environments.

[0005] In a first aspect, an embodiment of the present application provides a tin-plated layer surface passivation film, the tin-plated layer surface passivation film comprising a first passivation layer, and a second passivation layer located on the surface of the first passivation layer;

[0006] The first passivation layer is a chromium-containing passivation film layer, and the Cr content in the chromium-containing passivation film layer is 3 to 6 mg / m 2 ;

[0007] The second passivation layer is a Ti-Zr based passivation film layer, and the Ti element in the Ti-Zr based passivation film exists in the form of TiO2.

[0008] Furthermore, the first passivation layer is formed by electrochemical passivation using sodium dichromate.

[0009] Furthermore, the second passivation layer is formed by chemical passivation using a Ti-Zr series passivation solution, and the Ti content in the second passivation layer is 1 to 3 mg / m 2 .

[0010] In a second aspect, an embodiment of the present application provides a tinplate, which includes a steel substrate, a tinplate layer located on the surface of the steel substrate, and a passivation film located on the surface of the tinplate layer, wherein the passivation film is the passivation film on the surface of the tinplate layer described in the first aspect.

[0011] Furthermore, the tin-plated layer is formed by a reflow process using an MSA plating solution system.

[0012] Furthermore, the tin coating amount of the tin coating is 0.5 to 11.2 g / m 2 .

[0013] In a third aspect, an embodiment of the present application provides a passivation method for a tinplate surface, the passivation method comprising:

[0014] The surface of the tin-plated plate having a tin-plated layer is electrochemically passivated with sodium dichromate, and then chemically passivated with a Ti-Zr series passivation solution to obtain the tin-plated layer surface passivation film described in the first aspect on the surface of the tin-plated layer.

[0015] Furthermore, the tin-plated layer is formed by a reflow process using an MSA plating solution system.

[0016] Furthermore, the process parameters of the sodium dichromate electrochemical passivation include: the concentration of the sodium dichromate passivation solution is 20-30 g / L; the pH of the sodium dichromate passivation solution is 4-5; the passivation temperature is 35-50° C.; the passivation current density does not exceed 2.0 As / dm 2 .

[0017] Furthermore, the process parameters of the chemical passivation of the Ti-Zr series passivation solution include: in terms of mass fraction, the concentration of the Ti-Zr series passivation solution is 5-15%.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The present invention provides a tin-plated surface passivation film, which comprises a first passivation layer and a second passivation layer. The first passivation layer is a chromium-containing passivation film layer, and the Cr content in the chromium-containing passivation film layer is controlled to be 3 to 6 mg / m 2 On the one hand, through the higher Cr content (not less than 3mg / m 2 ), ensuring excellent corrosion resistance; on the other hand, preventing the Cr content from being too high (higher than 6mg / m 2 ) makes the passivation film too thick, which leads to a significant decrease in the bonding strength between the tinplate and the paint film during the canning process, and reduces the corrosion resistance of the coating film. The second passivation layer located on the surface of the first passivation layer is a Ti-Zr-based passivation film layer. The Ti element in the Ti-Zr-based passivation film layer exists in the form of TiO2, forming a dense passivation film layer, improving the salt spray resistance, and further improving the corrosion resistance of the chromium-containing passivation film layer. Therefore, through the synergistic protection of the two-layer structure passivation film, it is achieved that it has both excellent corrosion resistance and salt spray resistance, and can meet the use requirements of complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic diagram of the structure of a tinplate formed by the passivation method for the surface of a tinplate provided in an embodiment of the present application;

[0023] Among them, 1-Ti-Zr series passivation film layer; 2-chromium-containing passivation film layer; 3-tin plating layer; 4-tin-iron alloy layer; 5-steel substrate. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are for illustrating the present invention, rather than limiting the present invention.

[0025] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0026] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0027] Tinplate is a cold-rolled low-carbon steel sheet or strip coated with tin on both sides by electroplating. In order to improve the performance of tinplate, it is usually necessary to passivate the surface of the tinplate. The existing passivation treatment forms a single passivation film, which has a single function and cannot meet the use requirements of complex environments.

[0028] At present, there is no report on the research of tinplate with a two-layer structure passivation film.

[0029] The technical solution provided by the embodiment of the present invention is to solve the above technical problems, and the overall idea is as follows:

[0030] In a first aspect, an embodiment of the present application provides a tin-plated layer surface passivation film, the tin-plated layer surface passivation film comprising a first passivation layer, and a second passivation layer located on the surface of the first passivation layer;

[0031] The first passivation layer is a chromium-containing passivation film layer, and the Cr content in the chromium-containing passivation film layer is 3 to 6 mg / m2 ;

[0032] The second passivation layer is a Ti-Zr based passivation film layer, and the Ti element in the Ti-Zr based passivation film exists in the form of TiO2.

[0033] The present invention provides a tin-plated surface passivation film, which comprises a first passivation layer and a second passivation layer. The first passivation layer is a chromium-containing passivation film layer, and the Cr content in the chromium-containing passivation film layer is controlled to be 3 to 6 mg / m 2 On the one hand, through the higher Cr content (not less than 3mg / m 2 ), ensuring excellent corrosion resistance; on the other hand, preventing the Cr content from being too high (higher than 6mg / m 2 ) makes the passivation film too thick, which leads to a significant decrease in the bonding strength between the tinplate and the paint film during the canning process, and reduces the corrosion resistance of the coating film. The second passivation layer located on the surface of the first passivation layer is a Ti-Zr-based passivation film layer. The Ti element in the Ti-Zr-based passivation film layer exists in the form of TiO2, forming a dense passivation film layer, improving the salt spray resistance, and further improving the corrosion resistance of the chromium-containing passivation film layer. Therefore, through the synergistic protection of the two-layer structure passivation film, it is achieved that it has both excellent corrosion resistance and salt spray resistance, and can meet the use requirements of complex environments.

[0034] As an implementation manner of the embodiment of the present invention, the first passivation layer is formed by electrochemical passivation using sodium dichromate.

[0035] In the present application, a chromium-containing passivation film layer formed by electrochemical passivation with sodium dichromate is used as the first passivation layer, and Cr exists in the form of Cr2O3 and Cr(OH)3. The high Cr content, i.e., high Cr2O3 and Cr(OH)3, ensures excellent corrosion resistance. The sodium dichromate passivation solution in the present application can be directly purchased from the market.

[0036] As an implementation of the embodiment of the present invention, the second passivation layer is formed by chemical passivation using a Ti-Zr series passivation solution, and the Ti content in the second passivation layer is 1 to 3 mg / m 2 .

[0037] In this application, a Ti-Zr passivation film is formed as the second passivation layer by chemical passivation using a Ti-Zr passivation solution. The Ti element in the Ti-Zr passivation film exists in the form of TiO2, forming a dense passivation film layer, improving the salt spray resistance, and further improving the corrosion resistance of the chromium-containing passivation film layer. At the same time, the Ti element content is controlled to be 1 to 3 mg / m 2 The reason is that the Ti content is less than 1 mg / m 2The chromium-free passivation film is too thin and has low salt spray resistance; the Ti content is higher than 3mg / m 2 When the thickness of the chromium-free passivation film is too thick, the bonding force between the tinplate and the paint film during the coating and printing process of can making is significantly reduced, so that the corrosion resistance of the coating film is reduced. The Ti-Zr series passivation solution in this application can be directly purchased from the market.

[0038] In the second aspect, based on the same inventive concept, an embodiment of the present application provides a tinplate, which includes a steel substrate, a tinplate layer located on the surface of the steel substrate, and a passivation film located on the surface of the tinplate layer, and the passivation film is the passivation film on the surface of the tinplate layer described in the first aspect.

[0039] The tin-plated sheet provided in the embodiment of the present application, because it includes the surface passivation film of the tin-plated layer of the first aspect, naturally has its corresponding characteristics, that is, it has excellent corrosion resistance, salt spray resistance and other properties. It should be noted that the "tin-plated layer" mentioned in the present application should be understood as "a coating containing tin elements", including at least one of "a tin-iron alloy layer formed by tin elements and a steel substrate" and "a pure tin layer".

[0040] As an implementation manner of the embodiment of the present invention, the tin-plated layer is formed by a reflow method using an MSA plating solution system.

[0041] In the present application, the tin-plated layer is formed by a soft melting method using an MSA plating solution system to achieve green electroplating of tin. The resulting tin-plated layer includes a tin-iron alloy layer located on the surface of the steel substrate and a pure tin layer located on the surface of the tin-iron alloy layer. Preferably, the soft melting adopts pure induction soft melting, the soft melting temperature is 250-300°C, and the distance between the induction soft melting and the quenching tank is 4.2-6.5m. The main purpose is to form a tin-iron alloy layer, further improve the corrosion resistance of the tin-plated sheet, and meet the requirements of high-speed electroplating tin production; and the use of a non-contact pure induction soft melting method can effectively reduce the occurrence of surface defects.

[0042] As an implementation method of the present invention, the tin coating amount of the tin coating is 0.5 to 11.2 g / m 2 .

[0043] In this application, the tin coating amount is 0.5 to 11.2 g / m 2 , forming a dense tin-plated layer on the surface of the steel substrate, improving the performance of the tin-plated plate.

[0044] In a third aspect, based on the same inventive concept, an embodiment of the present application provides a passivation method for a tinplate surface, the passivation method comprising:

[0045] The surface of the tin-plated plate having a tin-plated layer is electrochemically passivated with sodium dichromate, and then chemically passivated with a Ti-Zr series passivation solution to obtain the tin-plated layer surface passivation film described in the first aspect on the surface of the tin-plated layer.

[0046] The passivation method for the surface of a tin-plated plate provided in the embodiment of the present application first performs electrochemical passivation with sodium dichromate and then performs chemical passivation with a Ti-Zr series passivation solution, so as to obtain a passivation film with a two-layer structure on the surface of the tin-plated plate, and can obtain a tin-plated plate with good adhesion, sulfur resistance, acid resistance, salt resistance, as well as excellent corrosion resistance and salt spray resistance.

[0047] As an implementation manner of the embodiment of the present invention, the tin-plated layer is formed by a reflow method using an MSA plating solution system.

[0048] In this application, preferably, a non-contact pure induction reflow method is used, which can effectively reduce the generation of surface defects; at the same time, the use of MSA environmentally friendly plating solution can meet the requirements of green electroplating development. This passivation method can adapt to 0.5~11.2g / m 2 Tin-plated layer, the production line production speed can meet the technical requirements of 500m / min.

[0049] As an implementation of the embodiment of the present invention, the process parameters of the sodium dichromate electrochemical passivation include: the concentration of the sodium dichromate passivation solution is 20-30 g / L; the pH of the sodium dichromate passivation solution is 4-5; the passivation temperature is 35-50 ° C; the passivation current density does not exceed 2.0 As / dm 2 .

[0050] In the present application, by controlling the above parameters, the Cr content in the chromium-containing passivation film layer as the first passivation layer can be 3 to 6 mg / m 2 On the one hand, through the high Cr content (not less than 3mg / m 2 ), ensuring excellent corrosion resistance; on the other hand, preventing the Cr content from being too high (higher than 6mg / m 2 ) makes the passivation film too thick, which leads to a significant decrease in the bonding strength between the tinplate and the paint film during the canning process, and reduces the corrosion resistance of the coating.

[0051] As an implementation method of the embodiment of the present invention, the process parameters of the chemical passivation of the Ti-Zr series passivation solution include: in terms of mass fraction, the concentration of the Ti-Zr series passivation solution is 5-15%.

[0052] In the present application, the concentration of the Ti-Zr system passivation solution is controlled to be 5-15%, so that the Ti element content in the Ti-Zr system passivation film as the second passivation layer can be 1-3 mg / m 2 .

[0053] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then proceed according to general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0054] Example 1

[0055] This example provides a passivation method for the surface of a tinplate, which specifically includes the following steps:

[0056] A 0.20mm thick continuous annealing or cover annealing electroplating substrate is obtained, and then the steel substrate is degreased, pickled, electroplated with tin, fluxed, soft melted, electrochemically passivated with sodium dichromate, chemically passivated with Ti-Zr series passivation solution, and oiled to obtain a tinplate steel coil or steel plate. Among them, the electroplating tin is the MSA plating solution system, and the tinning amount is 0.5g / m 2 The soft melting is pure induction soft melting, the soft melting temperature is 250℃, the distance between the induction soft melting and the quenching tank is 4.2m, the passivation first adopts sodium dichromate electrochemical passivation, and then adopts Ti-Zr series passivation liquid chemical passivation to form a passivation film, and the sodium dichromate passivation liquid is used in the electrochemical passivation, the concentration is 24g / L, the pH value is 4.3, the temperature is 41℃, and the current density is 0.4As / dm 2 , Cr content in chromium-containing passivation film is 3.8mg / m 2 ; A 6% Ti-Zr passivation solution was used in the chemical passivation, and the Ti content in the passivation film was 1.8 mg / m 2 .

[0057] The schematic diagram of the tinplate structure obtained through the above process is as follows Figure 1 As shown, the tinplate was tested according to QB / T 2763, and the adhesion reached Level 1, sulfur resistance Level 1, acid and salt resistance were qualified, corrosion resistance Level 1, and no rust in salt spray for 2 hours.

[0058] Example 2

[0059] This example provides a passivation method for the surface of a tinplate, which specifically includes the following steps:

[0060] A 0.17 mm thick continuous annealing or cover annealing electroplating substrate is obtained, and then the steel substrate is subjected to degreasing, pickling, electrotinning, fluxing, soft melting, sodium dichromate electrochemical passivation, chemical passivation using a Ti-Zr series passivation solution, and oiling to obtain a tinplate steel coil or steel plate, wherein the electrotinning is an MSA plating solution system, the tinning amount is 11.2 g / m2, the soft melting is pure induction soft melting, the soft melting temperature is 290°C, the induction soft melting is 6.5 m away from the quenching tank, the passivation first uses sodium dichromate electrochemical passivation, and then uses a Ti-Zr series passivation solution for chemical passivation to form a passivation film, and the sodium dichromate passivation solution is used in the electrochemical passivation, the concentration is 26 g / L, the pH value is 4.5, the temperature is 43°C, and the current density is 1.0 As / dm 2 , Cr content in chromium-containing passivation film is 5.4mg / m 2 ; The chemical passivation uses a 13% concentration of Ti-Zr passivation solution, and the Ti content in the passivation film is 2.3 mg / m 2 .

[0061] The tinplate obtained by the above process is tested according to QB / T 2763, and the adhesion reaches level 1, the sulfur resistance is level 1, the acid and salt resistance are qualified, the corrosion resistance is level 1, and there is no rust in salt spray for 6 hours.

[0062] Example 3

[0063] This example provides a passivation method for the surface of a tinplate, which specifically includes the following steps:

[0064] A 0.50mm thick continuous annealing or cover annealing electroplating substrate is obtained, and then the steel substrate is degreased, pickled, electroplated with tin, fluxed, soft melted, electrochemically passivated with sodium dichromate, chemically passivated with Ti-Zr series passivation solution, and oiled to obtain a tinplate steel coil or steel plate, wherein the electroplating tin is a MSA plating solution system, and the tinning amount is 2.8g / m 2 The soft melting is pure induction soft melting, the soft melting temperature is 260℃, the distance between the induction soft melting and the quenching tank is 4.2m, the passivation first adopts sodium dichromate electrochemical passivation, and then adopts Ti-Zr series passivation liquid chemical passivation to form a passivation film, and the sodium dichromate passivation liquid is used in the electrochemical passivation, the concentration is 25g / L, the pH value is 4.4, the temperature is 44℃, and the current density is 0.5As / dm 2 , Cr content in chromium-containing passivation film is 4.2mg / m 2 ; A 10% Ti-Zr passivation solution was used in the chemical passivation, and the Ti content in the passivation film was 2.1 mg / m 2 .

[0065] The tinplate obtained by the above process is tested according to QB / T 2763, and the adhesion reaches level 1, sulfur resistance level 1, acid and salt resistance are qualified, corrosion resistance level 1, and no rust in salt spray for 4 hours.

[0066] Comparative Example 1

[0067] A 0.20mm thick continuous annealing or cover annealing electroplating substrate is obtained, and then the steel substrate is degreased, pickled, electroplated with tin, fluxed, soft melted, electrochemically passivated with sodium dichromate, chemically passivated with Ti-Zr series passivation solution, and oiled to obtain a tinplate steel coil or steel plate. Among them, the electroplating tin is the MSA plating solution system, and the tinning amount is 0.5g / m 2 The soft melting is pure induction soft melting, the soft melting temperature is 250℃, the distance between the induction soft melting and the quenching tank is 4.2m, the passivation first adopts sodium dichromate electrochemical passivation, and then adopts Ti-Zr series passivation liquid chemical passivation to form a passivation film, and the sodium dichromate passivation liquid is used in the electrochemical passivation, the concentration is 24g / L, the pH value is 4.3, the temperature is 41℃, and the current density is 0.1As / dm 2 , Cr content in chromium-containing passivation film is 2mg / m 2 ; A 6% Ti-Zr passivation solution was used in the chemical passivation, and the Ti content in the passivation film was 1.8 mg / m 2 .

[0068] This example provides a passivation method for the surface of a tinplate, which differs from Example 1 only in that the Cr content in the chromium-containing passivation film layer is 2 mg / m 2 ; The remaining steps and parameters are the same.

[0069] The tinplate obtained by the above process is tested according to QB / T 2763, and the adhesion reaches level 1, sulfur resistance level 3, acid and salt resistance are qualified, corrosion resistance level 2, and no rust in salt spray for 2 hours.

[0070] Comparative Example 2

[0071] A 0.20mm thick continuous annealing or cover annealing electroplating substrate is obtained, and then the steel substrate is degreased, pickled, electroplated with tin, fluxed, soft melted, electrochemically passivated with sodium dichromate, chemically passivated with Ti-Zr series passivation solution, and oiled to obtain a tinplate steel coil or steel plate. Among them, the electroplating tin is the MSA plating solution system, and the tinning amount is 0.5g / m 2 The soft melting is pure induction soft melting, the soft melting temperature is 250℃, the distance between the induction soft melting and the quenching tank is 4.2m, the passivation first adopts sodium dichromate electrochemical passivation, and then adopts Ti-Zr series passivation liquid chemical passivation to form a passivation film, and the sodium dichromate passivation liquid is used in the electrochemical passivation, the concentration is 24g / L, the pH value is 4.3, the temperature is 41℃, and the current density is 4As / dm 2 , Cr content in chromium-containing passivation film is 7mg / m 2 ; A 6% Ti-Zr passivation solution was used in the chemical passivation, and the Ti content in the passivation film was 1.8 mg / m 2 .

[0072] This example provides a passivation method for the surface of a tinplate, which differs from Example 1 only in that the Cr content in the chromium-containing passivation film layer is 7 mg / m 2 ; The remaining steps and parameters are the same.

[0073] The tinplate obtained by the above process is tested according to QB / T 2763, and the adhesion reaches level 3, the sulfur resistance is level 2, the acid and salt resistance are qualified, the corrosion resistance is level 2, and there is no rust in salt spray for 2 hours.

[0074] It should be noted that, in this article, relational terms such as "first" and "second" are only used 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. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0075] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be 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 the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A tin-plated surface passivation film, characterized in that: The passivation film on the surface of the tin-plated layer comprises a first passivation layer and a second passivation layer located on the surface of the first passivation layer; The first passivation layer is a chromium-containing passivation film layer, and the Cr content in the chromium-containing passivation film layer is 3-6 mg / m 2 ; The second passivation layer is a Ti-Zr based passivation film layer, and the Ti element in the Ti-Zr based passivation film exists in the form of TiO2, and the Ti element content in the second passivation layer is 1-3 mg / m 2 ; The tin coating amount of the tin coating is 0.5-11.2 g / m 2 .

2. The tin-plated layer surface passivation film according to claim 1, characterized in that: The first passivation layer is formed by electrochemical passivation using sodium dichromate.

3. The tin-plated layer surface passivation film according to claim 1, characterized in that: The second passivation layer is formed by chemical passivation using a Ti-Zr series passivation solution.

4. A tinplate, comprising a steel substrate, a tinplate layer located on the surface of the steel substrate, and a passivation film located on the surface of the tinplate layer, characterized in that: The passivation film is the tin-plating surface passivation film according to any one of claims 1 to 3.

5. The tin-plated sheet according to claim 4, wherein the tin-plated layer is formed by a reflow method using an MSA plating solution system.

6. A method for passivating the surface of a tinplate, characterized in that: The passivation method comprises: The surface of the tin-plated plate having a tin-plated layer is subjected to electrochemical passivation with sodium dichromate, and then chemical passivation is performed using a Ti-Zr series passivation solution to obtain a tin-plated layer surface passivation film as claimed in any one of claims 1 to 3 on the surface of the tin-plated layer.

7. The passivation method for the surface of a tinplate according to claim 6, characterized in that: The tin-plated layer is formed by a reflow method using an MSA plating solution system.

8. The passivation method for the surface of a tinplate according to claim 6, characterized in that: The process parameters of the sodium dichromate electrochemical passivation include: the concentration of the sodium dichromate passivation solution is 20-30 g / L; the pH of the sodium dichromate passivation solution is 4-5; the passivation temperature is 35-50° C.; the passivation current density does not exceed 2.0 As / dm 2 .

9. The passivation method for the surface of a tinplate according to claim 6, characterized in that: The process parameters of the chemical passivation of the Ti-Zr series passivation solution include: in terms of mass fraction, the concentration of the Ti-Zr series passivation solution is 5-15%.

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