Tinplate having chromium-free surface and manufacturing method therefor

Abstract

Disclosed in the present invention is a tinplate having a chromium-free surface, comprising a substrate and a tin plating plated on the surface of the substrate. The surface of the tin plating has a passivation film. The passivation film contains the following effective elements: 0.5-6 mg / m2 of Ti; at least one of Mn, Zn, and Mo having a total amount of 1-8 mg / m2 ; 0.5-5 mg / m2 of P; and 0.01-0.5 mg / m2 of Si. Further disclosed in the present invention is a method for manufacturing the tinplate, comprising the steps of: electroplating tin on the surface of a substrate; subjecting the tinplate to a tin plating reflow alloying treatment; performing electrolysis pretreatment; and passivation treatment: uniformly applying a chromium-free passivation solution to the surface of the tinplate by means of immersion and / or spraying, and then drying, wherein the chromium-free passivation solution contains: a water-soluble salt of titanium, at least one of water-soluble salts of manganese, zinc and molybdenum, an inorganic phosphate, a silicon-containing oligomer, and / or a modified silica sol.

Description

Surface chromium-free tin-plated steel sheet and method for manufacturing the same TECHNICAL FIELD

[0001] The present invention relates to a steel sheet and a method for manufacturing the same, and more particularly, to a tin-plated steel sheet and a method for manufacturing the same. BACKGROUND

[0002] The tin-plated steel sheet is widely used as a metal can packaging material in the fields of food, beverage, and chemical industry. The tin-plated steel sheet has good formability, strong corrosion resistance, and is easy to print and coat, and a metal can manufactured using the tin-plated steel sheet has the advantages of a beautiful appearance, high can body strength, and a long shelf life of a can content, and has been widely used for a long time.

[0003] The tin-plated steel sheet is a steel sheet on which a pure tin layer is plated on a surface of a thin steel sheet by an electroplating method, and then a tin-iron alloy layer is formed between the pure tin layer and a steel substrate through a tin layer reflowing (alloying) process. Also, in order to secure good use properties of the tin-plated steel sheet for packaging, a passivation process is required to be performed on the surface of the tin-plated steel sheet.

[0004] A conventional passivation method of the tin-plated steel sheet is a chromate passivation process, and generally, the tin-plated steel sheet is subjected to an electrolytic treatment as a cathode in a dichromate or chromic anhydride solution, and hexavalent chromium in the solution is reduced to trivalent chromium oxide or metallic chromium and deposited on the surface of the tin-plated steel sheet. Although the tin-plated steel sheet itself does not contain hexavalent chromium, the production process uses a highly toxic hexavalent chromate, and thus the environmental friendliness of the production process is poor. In order to realize green environmental protection in the production of the tin-plated steel sheet, the prior art:

[0005] Chinese patent literature with the publication number CN101010452A and the publication date of August 1, 2007, entitled "Surface-treated metal material, method for surface treatment thereof, and metal material coated with resin, can, and can lid" discloses a surface-treated metal material and a method for surface treatment thereof, which forms an inorganic treatment film layer containing at least one of Ti, Zr, and Al, and further containing O and F on a metal surface by a cathodic electrolysis technique, and then coats a silane coupling agent or a water-soluble organic compound containing a phenol on the surface of the inorganic film layer to form a composite surface treatment layer.

[0006] Chinese patent literature with the publication number CN103429795A and the publication date of December 4, 2013, entitled "Multi-stage pretreatment of tinplate before coating with paint" discloses a two-step method for the corrosion prevention pretreatment of tinplate, which includes anodically polarizing the tin-plated steel sheet in a solution containing at least one inert water-soluble salt, and then contacting the tin-plated steel sheet with a water-soluble inorganic salt containing Zr, Ti, Hf, and / or Si and an organic polymer. SUMMARY

[0007] An object of the present application is to provide a surface-chromium-free tin-plated steel sheet having excellent surface properties without chromium on the surface.

[0008] To achieve the above object, the present application provides a surface-chromium-free tin-plated steel sheet including a base plate and a tin-plated layer plated on the surface of the base plate, the surface of the tin-plated layer having a passivation film; the passivation film containing the following effective elements:

[0009] Ti: 0.5 to 6 mg / m 2 ;

[0010] at least one of Mn, Zn, and Mo: 1 to 8 mg / m 2 ;

[0011] P: 0.5 to 5 mg / m 2 ;

[0012] Si: 0.01 to 0.5 mg / m 2 .

[0013] Further, in the surface-chromium-free tin-plated steel sheet according to the present application, the content of each of the effective elements in the passivation film is further:

[0014] Ti: 1 to 4 mg / m 2 ;

[0015] at least one of Mn, Zn, and Mo: 3 to 6 mg / m 2 ;

[0016] P: 1 to 4 mg / m 2 ;

[0017] Si: 0.05 to 0.3 mg / m 2 .

[0018] Further, in the surface-chromium-free tin-plated steel sheet according to the present application, the total content of the effective elements in the passivation film is 3 to 15 mg / m 2 .

[0019] Further, in the surface-chromium-free tin-plated steel sheet according to the present application, the total content of the effective elements in the passivation film is 6 to 12 mg / m 2 .

[0020] In some embodiments, the total content of Mn, Zn, and Mo in the passivation film is 5 to 8 mg / m 2 , 1 to 5 mg / m 2 , or 3 to 5 mg / m 2 .

[0021] In some embodiments, the content of P in the passivation film is 1-5 mg / m 2 , 0.5-2.15 mg / m 2 , 1-2.15 mg / m 2 , or 3.85-5 mg / m 2 .

[0022] In some embodiments, the content of Si in the passivation film is 0.13-0.3 mg / m 2 , 0.01-0.13 mg / m 2 , or 0.3-0.5 mg / m 2 .

[0023] The surface wetting tension of the surface-chromium-free tin-plated steel plate of the present application is 35-40 mN / m, for example, 35-38 mN / m, 38-40 mN / m. In this context, the testing method of the surface wetting tension of the surface-chromium-free tin-plated steel plate is the method for testing the surface tension of the testing material (dynes method) in the standard GB / T 14216-2008 "Determination of Wetting Tension of Plastic Film and Sheet".

[0024] The adhesion of the surface-chromium-free tin-plated steel plate of the present application is grade 1 or grade 2. In this context, the adhesion test adopts the paint film adhesion test method specified in QB / T 2673-2006 "Coated Tin (or Chromium) Plated Steel Sheet".

[0025] Another object of the present application is to provide a manufacturing method of a surface-chromium-free tin-plated steel plate, which does not use the environment-harmful hexavalent chromium in the manufacturing process, and still can obtain a tin-plated steel plate with excellent comprehensive surface performance and food contact safety.

[0026] In order to achieve the above-mentioned objects, the present application provides a manufacturing method of a surface-chromium-free tin-plated steel plate, which comprises the steps of:

[0027] Electroplating tin on the surface of the substrate;

[0028] Softening and alloying treatment of the tin-plated layer of the tin-plated steel plate;

[0029] Electrolytic pretreatment: immersing the tin-plated steel plate into a neutral inorganic phosphate solution to perform anodic treatment, and then performing cathodic treatment;

[0030] Passivation treatment: uniformly coating a chromium-free passivation solution onto the surface of the tin-plated steel plate in the form of immersion and / or spraying, and then drying; wherein the chromium-free passivation solution contains: a water-soluble salt of titanium, at least one of water-soluble salts of manganese, zinc and molybdenum, an inorganic phosphate, a silicon-containing oligomer and / or modified silica sol.

[0031] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the concentration of the water-soluble salt of titanium in the chromium-free passivation liquid is 0.4 to 2.5 g / L in terms of Ti element content; the total concentration of the water-soluble salts of manganese, zinc and molybdenum in the chromium-free passivation liquid is 1 to 6 g / L in terms of total content of Mn, Zn and Mo elements; the concentration of the inorganic phosphate in the chromium-free passivation liquid is 0.5 to 3 g / L in terms of P element content; and the concentration of the silicon-containing oligomer and / or modified silica sol in the chromium-free passivation liquid is 0.005 to 0.3 g / L in terms of Si element content.

[0032] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the concentration of the water-soluble salt of titanium in the chromium-free passivation liquid is 0.8 to 2 g / L in terms of Ti element content; the total concentration of the water-soluble salts of manganese, zinc and molybdenum in the chromium-free passivation liquid is 2 to 4 g / L in terms of total content of Mn, Zn and Mo elements; the concentration of the inorganic phosphate in the chromium-free passivation liquid is 0.8 to 2 g / L in terms of P element content; and the concentration of the silicon-containing oligomer and / or modified silica sol in the chromium-free passivation liquid is 0.025 to 0.2 g / L in terms of Si element content.

[0033] In some embodiments, the concentration of the water-soluble salt of titanium in the chromium-free passivation liquid is 0.4 to 2 g / L or 0.8 to 2.5 g / L in terms of Ti element content. In some embodiments, the concentration of the water-soluble salts of manganese, zinc and molybdenum in the chromium-free passivation liquid is 2 to 6 g / L or 3 to 6 g / L in terms of total content of Mn, Zn and Mo elements. In some embodiments, the concentration of the inorganic phosphate in the chromium-free passivation liquid is 1 to 3 g / L or 0.5 to 1.2 g / L in terms of P element content. In some embodiments, the concentration of the silicon-containing oligomer and / or modified silica sol in the chromium-free passivation liquid is 0.005 to 0.15 g / L or 0.1 to 0.3 g / L in terms of Si element content.

[0034] Further, in the method of manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the water-soluble salt of titanium is selected from at least one of potassium fluotitanate, ammonium fluotitanate, potassium titanyl oxalate, and titanyl oxysulfate; the inorganic phosphate is selected from at least one of potassium dihydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, and sodium metaphosphate; the silicon-containing oligomer is selected from a silane oligomer; when the water-soluble salt of manganese is contained, it is selected from at least one of manganese dihydrogen phosphate, potassium permanganate, and manganese nitrate; when the water-soluble salt of zinc is contained, it is selected from at least one of zinc dihydrogen phosphate, zinc sulfate, and zinc nitrate; and when the water-soluble salt of molybdenum is contained, it is selected from at least one of sodium molybdate and ammonium molybdate. In some embodiments, the water-soluble salt of titanium is selected from one of potassium fluotitanate, ammonium fluotitanate, and titanyl oxysulfate; or from two of potassium fluotitanate, ammonium fluotitanate, potassium titanyl oxalate, and titanyl oxysulfate; or is potassium fluotitanate, ammonium fluotitanate, and titanyl oxysulfate. In some embodiments, the water-soluble salt of manganese is manganese nitrate, or is selected from two or more of manganese dihydrogen phosphate, potassium permanganate, and manganese nitrate. In some embodiments, the water-soluble salt of zinc is zinc dihydrogen phosphate, zinc sulfate, or zinc nitrate; or the water-soluble salt of zinc is selected from two or more of zinc dihydrogen phosphate, zinc sulfate, and zinc nitrate. In some embodiments, the inorganic phosphate is sodium dihydrogen phosphate or sodium metaphosphate; or the inorganic phosphate is selected from two or more of potassium dihydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, and sodium metaphosphate. In some embodiments, the silicon-containing oligomer is a silane oligomer.

[0035] Herein, the silane oligomer is a macromolecular compound formed by connecting a plurality of silane molecules, and has a number average molecular weight of 1000 to 10000. In some embodiments, the silane oligomer can be prepared from a silicon-containing raw material through a hydrolysis and polymerization step according to the conventional art. The silicon-containing raw material that can be hydrolyzed to a silanol includes, but is not limited to, halosilane, alkoxysilane, silazane, silicon ester, siloxane, hydrosilane, alkylsilane, etc. In some embodiments, the silicon-containing raw material is selected from tetramethylsilane, glycidyloxypropylcyclotetrasiloxane, trimethoxysilane, and sulfur-containing silane coupling agent. Preferably, the tetramethylsilane is a cage-structured tetramethylsilane. Preferably, the glycidyloxypropylcyclotetrasiloxane is a propylsilane containing four epoxy groups. Preferably, the trimethoxysilane is 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Preferably, the sulfur-containing silane coupling agent is a triethoxy-containing sulfur-containing silane.

[0036] In some embodiments, the silane oligomer is prepared by polymerization of tetramethylsilane and glycidyl ether oxypropyl cyclotetrasiloxane. The method for preparing the silane oligomer can include the steps of adding tetramethylsilane and glycidyl ether oxypropyl cyclotetrasiloxane into a solvent, stirring mechanically until uniform, adding phosphoric acid, and continuing the reaction. In some embodiments, the solvent is anhydrous ethanol. In some embodiments, the phosphoric acid is a 1 mol / L aqueous solution. In some embodiments, the stirring time is 60-120 min. In some embodiments, the volume ratio of tetramethylsilane to glycidyl ether oxypropyl cyclotetrasiloxane is 1:(1-1.1), the volume ratio of tetramethylsilane to anhydrous ethanol is (0.03-0.08):1, and the volume of phosphoric acid added is 30%-60% of the volume of tetramethylsilane.

[0037] In some embodiments, the silane oligomer is prepared by polymerization of trimethoxysilane and sulfur-containing silane coupling agent. The method for preparing the silane oligomer can include: (1) adding trimethoxysilane and sulfur-containing silane coupling agent into anhydrous ethanol and stirring to form a mixed solution A; and (2) reacting mixed solution A with water and phosphoric acid to obtain the silane oligomer after sufficient hydrolysis. In some embodiments, in mixed solution A, the mass percentages of trimethoxysilane, sulfur-containing silane coupling agent, and anhydrous ethanol are 2%-6%, 10%-15%, and 80%-85%, respectively; and the mass ratio of trimethoxysilane to sulfur-containing silane coupling agent is trimethoxysilane:sulfur-containing silane coupling agent = 1:(2-3). In some embodiments, in step (2), the mass percentages of solution A, phosphoric acid, and deionized water are 95%-98%, 0.5%-2%, and the balance, respectively; and the concentration of phosphoric acid is 1 mol / L. In step (1), the stirring time is 5-15 min. In step (2), the reaction time of solution A with water and phosphoric acid is 60-180 min.

[0038] The silane oligomer and the method for preparing the same disclosed in CN118814152A and CN118581449A can be used in the present application.

[0039] In this document, the modified silica sol is a silane coupling agent-modified silica sol. The silane coupling agent can be one or more of various silane coupling agents commonly used in the modification of silica sol in the art, including various epoxy silanes and amino silanes. Thus, exemplary modified silica sols include epoxy silane-modified silica sols and amino silane-modified silica sols. In the preparation of the modified silica sol, the amount of silane coupling agent added is not more than 10 wt%.

[0040] When the silicon-containing oligomer and modified silica sol are used, the amount of the silicon-containing oligomer and modified silica sol is not particularly limited, as long as the total concentration of the silicon-containing oligomer and modified silica sol in the passivation solution is within the range defined herein, such as 0.025-0.2 g / L, in terms of Si element content.

[0041] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the chromium-free passivation solution further contains a surface wetting agent. The surface wetting agent can improve the surface wetting ability of the chromium-free passivation solution. The surface wetting agent can be a polyhydric alcohol, such as polyethylene glycol and / or propylene glycol.

[0042] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the total content of the surface wetting agent, such as polyethylene glycol and / or propylene glycol, is 0.5-5 g / L, such as 0.5-3.5 g / L, 3-5 g / L or 0.5-1.5 g / L.

[0043] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the solvent of the chromium-free passivation solution is water.

[0044] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the pH value of the chromium-free passivation solution is 2-6, such as 3.5-6 or 4-6.

[0045] In some embodiments, phosphoric acid and sodium phosphate can be used to adjust the pH value of the chromium-free passivation solution.

[0046] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the temperature of the chromium-free passivation solution is 25-55 °C.

[0047] In some embodiments, the temperature of the chromium-free passivation solution can be further controlled to be 35-45 °C, 25-40 °C, 25-35 °C.

[0048] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the time of the passivation treatment (i.e. the time of coating + drying) is controlled to be 0.5-10 s.

[0049] In some embodiments, the time of the passivation treatment can be further controlled to be 3-6 s, 3-10 s or 8-10 s.

[0050] In some embodiments, the method of drying comprises (1) hot air blowing and induction heating; or (2) hot air blowing and radiation heating. The hot air blowing preferably uses dry hot air blowing.

[0051] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the electric quantity of the anode treatment is 0.1-1 C / dm2 ; and / or the cathodic treatment electric quantity is 0.05-0.5 C / dm 2 .

[0052] In some more specific embodiments, the cathodic treatment electric quantity is not more than 1 / 2 of the anodic treatment electric quantity.

[0053] In some further embodiments, the anodic treatment electric quantity can be further controlled to be 0.2-0.6 C / dm 2 , and the cathodic treatment electric quantity can be further controlled to be 0.1-0.3 C / dm 2 .

[0054] In some embodiments, the tin-plated steel sheet is first subjected to an anodic treatment (at this time, the tin-plated steel sheet is an anode) by being immersed in a neutral inorganic phosphate solution, and then immediately subjected to a cathodic treatment (at this time, the tin-plated steel sheet is a cathode) in the same solution. In some embodiments, the neutral inorganic phosphate solution can have a temperature of 20-50°C.

[0055] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the neutral inorganic phosphate solution is an alkali metal phosphate solution. In some embodiments, the alkali metal is selected from one or both of sodium and potassium. In some embodiments, the inorganic phosphate is selected from one or both of sodium dihydrogen phosphate and sodium hydrogen phosphate. Herein, sodium hydrogen phosphate refers to sodium monohydrogen phosphate.

[0056] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, a phosphate that functions as a buffer pair, such as sodium dihydrogen phosphate and sodium hydrogen phosphate, can be used as the inorganic phosphate, and the pH of the neutral inorganic phosphate solution can be adjusted by adjusting the amounts of the two.

[0057] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the neutral inorganic phosphate solution has a concentration of 5-30 g / l.

[0058] In some embodiments, the concentration of the neutral inorganic phosphate aqueous solution can be further controlled to be 10-20 g / l or 25-30 g / l.

[0059] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the neutral inorganic phosphate solution has a temperature of 20-50°C.

[0060] In some embodiments, the temperature of the neutral inorganic phosphate aqueous solution can be further controlled to be 30-40°C or 35-50°C.

[0061] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the tin plating on the surface of the substrate can be performed by using a conventional method in the art, such as an acid sulfate type tin plating process or an acid sulfonate type tin plating process. In some embodiments, the plating solution of the acid sulfate type tin plating process comprises stannous sulfate. In some embodiments, the plating solution of the acid sulfonate type tin plating process comprises one or more of stannic methanesulfonate and stannic phenolsulfonate.

[0062] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the amount of tin plating on the surface of the substrate is 1-5 g / m 2 , further 2-4 g / m 2 , 2-2.8 g / m 2 or 2.8-4 g / m 2 . In some embodiments, the substrate is tin-plated on both sides.

[0063] Further, in the method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application, the tin-plated steel sheet can be subjected to a softening alloying treatment.

[0064] In some embodiments, the tin-plated steel sheet is heated to 240-310°C in the softening alloying treatment. Further, the heating of the tin-plated steel sheet can be performed by resistance heating or induction heating.

[0065] In some embodiments, the softening alloying treatment is performed for 0.5-3 s.

[0066] Compared with the prior art, the surface-chromium-free tin-plated steel sheet and the method for manufacturing the same according to the present application have the following advantages and beneficial effects:

[0067] The surface-chromium-free tin-plated steel sheet according to the present application has good surface properties without chromium on the surface, and the coating adhesion and the sulfurization spot resistance are comparable to those of a steel sheet treated with a chromium-containing passivation solution.

[0068] The method for manufacturing the surface-chromium-free tin-plated steel sheet according to the present application does not use hexavalent chromium, which is harmful to the environment, in the process, and the surface treatment process is environmentally friendly, which can replace the chromium passivation process to realize green production of tin-plated steel sheets. DETAILED DESCRIPTION

[0069] The surface-chromium-free tin-plated steel sheet and the method for manufacturing the same according to the present application will be further explained and described below in conjunction with specific examples, however, the explanation and description do not constitute undue limitations on the technical solutions of the present application.

[0070] The silane oligomer was prepared by the following method: 800 μL of tetramethylcage silane and 800 μL of glycidyl ether oxypropyl cyclotetrasiloxane were taken with a pipette and added to 16.8 g of absolute ethanol, stirred mechanically for 10 min to form a homogeneous solution, the pH was adjusted with 30 μL of 1 mol / L H3PO4, and the silane oligomer was obtained after 1 h of further reaction.

[0071] Examples 1-8 and Comparative Examples 1-2

[0072] The chromium-free tin-plated steel sheets of Examples 1-8 according to the present application were prepared by the following steps:

[0073] (1) Tin plating on the surface of the substrate: The plating was carried out in a stannous sulfate, tin methanesulfonate or tin phenolsulfonic acid plating solution. The steel sheet was plated on both sides with tin, and the tin plating amount of Examples 1-8 was 2.8 g / m 2 .

[0074] (2) Softening and alloying treatment of the tin plating layer: The steel strip was rapidly heated to a temperature of 240-310 °C (the melting point of tin is 232 °C) by resistance heating or induction heating. By completely melting the tin layer in a short time (0.5-3 s), tin and iron can be diffused and intermingled to form a tin-iron alloy layer.

[0075] (3) Electrolytic pretreatment of the tin plating layer: The tin-plated steel sheet was immersed in a neutral inorganic phosphate solution for anodic treatment (at this time the tin-plated steel sheet is an anode), the anodic treatment can be 0.1-1 C / dm 2 , and then immediately cathodic treatment (at this time the tin-plated steel sheet is a cathode) was carried out in the same solution, the cathodic treatment can be 0.05-0.5 C / dm 2 , and the solution temperature can be 20-50 °C. The inorganic phosphate in the neutral inorganic phosphate solution comes from sodium dihydrogen phosphate and sodium hydrogen phosphate, by adjusting the ratio of sodium dihydrogen phosphate and sodium hydrogen phosphate, the pH value of the phosphate solution can be neutral; the concentration of the neutral inorganic phosphate aqueous solution can be 5-30 g / l.

[0076] (4) Passivation treatment: The temperature of the chromium-free passivation solution was controlled at 25-55 °C, and the solution was uniformly coated on the surface of the tin-plated steel sheet by immersion or spraying or a combination of immersion + spraying, then the excess passivation solution was removed by a pair of squeeze rollers, then dry hot air was used for blowing, and the coated chromium-free passivation solution was rapidly dried into a film by one of the following combinations: superimposed induction heating, radiation heating, and the coating and drying time was controlled at 0.5-10 s. The composition of the chromium-free passivation solution is shown in Table 1-1 and Table 1-2.

[0077] Table 1-1 and Table 1-2 list the ingredient contents of the chromium-free passivation solution of Examples 1-8 described in the present application.

[0078] Table 1-1 (the balance is deionized water)

[0079] Table 1-2.

[0080] Each reagent used in the above examples can be purchased from a commercial source.

[0081] Table 2 lists the specific process parameters of the electrolytic pretreatment and passivation treatment processes of Examples 1-8 of the present application.

[0082] Table 2.

[0083] Table 3 lists the effective element contents of the surface chromium-free tinplate sheets of Examples 1-8 prepared above.

[0084] Table 3.

[0085] Note: The effective element contents in the above Table 3 are measured by chemically dissolving the chromium-free passivation film on the surface of a tinplate sheet of a certain area, determining the element contents in the solution resulting from the dissolution of the chromium-free passivation film composition by inductively coupled plasma emission spectroscopy (ICP), and converting the element contents on the surface of the tinplate sheet.

[0086] In order to verify the surface properties of the surface chromium-free tinplate sheets of Examples 1-8 described in the present application, the surface properties of the tinplate sheets of Examples 1-8 and Comparative Examples 1-2 were detected.

[0087] The surface chromium-free tinplate sheets of Examples 1-8 and the comparative steel of Comparative Example 1-2 were sampled, and their surface properties were detected, and the detection results are listed in Table 5. It should be noted that the tinplate sheets of Comparative Example 1 and Comparative Example 2 in the present application are passivated by conventional cathodic electrolytic chromate (specifically, sodium dichromate), and the single-side tin plating amount is 2.8 g / m 2 . Among them, the chromium passivation amount of Comparative Example 1 is 3 mg / m 2 , and the chromium passivation amount of Comparative Example 2 is 5 mg / m 2 .

[0088] Surface wetting property: The surface wetting tension of the chromium-free surface treated tinplate sheet was tested by the method (dynes method) for testing the surface tension of the test material in the standard GB / T 14216-2008 "Determination of Wetting Tension of Plastic Film and Sheet", and the higher the value, the better the surface wetting property of the tinplate sheet.

[0089] Paint film adhesion performance: the paint film adhesion test method specified in QB / T 2673-2006 "Coated Tin (or Chromium) Steel Sheet" was used to evaluate the adhesion performance of the chromium-free surface treated tinplate. The test sample was a painted tinplate, and the type of paint used was epoxy phenolic paint, with a dry film weight of 6-7 g / m 2 .

[0090] Sulfuration spot resistance performance: the sulfuration spot resistance test method specified in QB / T 2673-2006 "Coated Tin (or Chromium) Steel Sheet" was used to test the sample, which was a painted tinplate, and the type of paint used was epoxy phenolic paint, with a dry film weight of 6-7 g / m 2 . The surface sulfuration blackening of the sample was observed, and the sulfuration spot resistance performance grade was defined according to different degrees of sulfuration blackening. Table 4 lists the definition of the sulfuration spot resistance performance grade.

[0091] Table 4.

[0092] Table 5 lists the surface performance test results of the chromium-free surface treated tinplate of Examples 1-8 and the comparative steel of Comparative Examples 1-2.

[0093] Table 5.

[0094] As can be seen from the above Table 5, the paint film adhesion and sulfuration spot resistance performance of the chromium-free surface treated tinplate of Examples 1-8 prepared by the manufacturing method of the present application are not significantly different from those of the conventional cathode electrolytic chromium passivated tinplate, while the surface wetting performance is better than that of the chromium-containing passivated tinplate, which shows that the chromium-free surface treated tinplate of the present application has good surface performance.

[0095] It should be noted that the above listed examples are only specific embodiments of the present application. Obviously, the present application is not limited to the above examples, and similar changes or modifications made in accordance with the disclosure of the present application are directly derived or easily conceived by those skilled in the art, and should all fall within the scope of protection of the present application.

Claims

1. A chromium-free tin-plated steel sheet, comprising a substrate and a tin-plated layer coated on the surface of the substrate, wherein the surface of the tin-plated layer has a passivation film; characterized in that, The passivation film contains the following effective elements: Content is 0.5-6 mg / m³ 2 Ti; Total content is 1-8 mg / m³ 2 At least one of Mn, Zn, and Mo; Content is 0.5-5 mg / m³ 2 P; Si with a content of 0.01 - 0.5 mg / m 2 is present.

2. The chromium-free tin-plated steel sheet as described in claim 1, characterized in that, The content of each effective element in the passivation film is further as follows: Ti: 1-4mg / m 2 ; Total content is 3-6 mg / m³ 2 At least one of Mn, Zn, and Mo; P:1-4mg / m 2 ; Si: 0.05-0.3mg / m 2 。 3. The chromium-free tin-plated steel sheet as described in claim 1, characterized in that, The total content of the effective elements in the passivation film is 3-15 mg / m³. 2 Preferably 6-12 mg / m³ 2 .

4. The chromium-free tin-plated steel sheet as described in claim 1, characterized in that, The surface wetting tension of the chromium-free tin-plated steel sheet is 35-40 mN / m; and / or, the adhesion of the chromium-free tin-plated steel sheet is grade 1 or 2.

5. The method for manufacturing a chromium-free tin-plated steel sheet as described in any one of claims 1-4, characterized in that... Including the following steps: Tin plating is performed on the substrate surface; The tin-plated steel sheet is subjected to a softening alloying treatment for the tin plating layer. Electrolytic pretreatment: The tin-plated steel sheet is first anoly treated by immersing it in a neutral inorganic phosphate solution, and then catholyly treated. Passivation treatment: A chromium-free passivation solution is uniformly coated onto the surface of a tin-plated steel sheet by immersion and / or spraying, and then dried; wherein the chromium-free passivation solution contains: a water-soluble salt of titanium, at least one of a water-soluble salt of manganese, zinc and molybdenum, an inorganic phosphate, a silicon-containing oligomer and / or a modified silica sol.

6. The manufacturing method as described in claim 5, characterized in that, In the chromium-free passivation solution, the concentration of the water-soluble salt of titanium, based on the Ti element content, is 0.4-2.5 g / L; the total concentration of the water-soluble salt of manganese, zinc, and molybdenum, based on the total Mn, Zn, and Mo element content, is 1-6 g / L; the total concentration of the inorganic phosphate, based on the P element content, is 0.5-3 g / L; and the concentration of the silicon-containing oligomer and / or modified silica sol, based on the Si element content, is 0.005-0.3 g / L. Preferably, the concentration of the water-soluble salt of titanium is 0.8-2 g / L; the total concentration of the water-soluble salt of manganese, zinc, and molybdenum is 2-4 g / L; the concentration of the inorganic phosphate is 0.8-2 g / L; and the concentration of the silicon-containing oligomer and / or modified silica sol is 0.025-0.2 g / L. Preferably, the modified silica sol is an epoxy silane-modified silica sol or an aminosilane-modified silica sol.

7. The manufacturing method as described in claim 5, characterized in that, The water-soluble salt of titanium is selected from at least one of potassium fluorotitanate, ammonium fluorotitanate, potassium titanium oxalate, and titanium oxysulfate; the inorganic phosphate is selected from at least one of potassium dihydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, and sodium metaphosphate; the silicon-containing oligomer is selected from silane oligomers; the water-soluble salt of manganese is selected from at least one of manganese dihydrogen phosphate, potassium permanganate, and manganese nitrate; the water-soluble salt of zinc is selected from at least one of zinc dihydrogen phosphate, zinc sulfate, and zinc nitrate; the water-soluble salt of molybdenum is selected from at least one of sodium molybdate and ammonium molybdate; preferably, the modified silica sol is an epoxysilane-modified silica sol or an aminosilane-modified silica sol; preferably, the silane oligomer is obtained by polymerization of tetramethylsilane and glycidyl etheroxypropylcyclotetrasiloxane, or the silane oligomer is obtained by polymerization of trimethoxysilane and a sulfur-containing silane coupling agent.

8. The manufacturing method as described in claim 5, characterized in that, The chromium-free passivation solution also contains a surface wetting agent, preferably polyethylene glycol and / or propylene glycol; preferably, the total content of the surface wetting agent, such as polyethylene glycol and / or propylene glycol, is 0.5-5 g / L.

9. The manufacturing method as described in claim 5, characterized in that, The pH value of the chromium-free passivation solution is 2-6; and / or the temperature of the chromium-free passivation solution is 25-55℃.

10. The manufacturing method as described in claim 5, characterized in that, The passivation treatment time is 0.5-10s.

11. The manufacturing method as described in claim 5, characterized in that, The charge for the anodic treatment is 0.1-1 C / dm³. 2 ; and / or the charge of the cathode treatment is 0.05-0.5 C / dm. 2 .

12. The manufacturing method as described in claim 5, characterized in that, The concentration of the neutral inorganic phosphate solution is 5-30 g / L; and / or the temperature of the neutral inorganic phosphate solution is 20-50 °C.

13. The manufacturing method as described in claim 5, characterized in that, In the passivation process, dry hot air is used for purging, and drying is carried out in combination with one of induction heating or radiation heating.

14. A chromium-free passivation solution comprising: (1) a water-soluble salt of titanium, (2) at least one of water-soluble salts of manganese, zinc and molybdenum, (3) an inorganic phosphate, (4) a silicon-containing oligomer and / or modified silica sol, and (5) an optional surface wetting agent such as polyethylene glycol and / or propylene glycol; preferably, in the chromium-free passivation solution, the concentration of the water-soluble salt of titanium, based on the Ti element content, is 0.4-2.5 g / L; the total concentration of the water-soluble salts of manganese, zinc and molybdenum, based on the total Mn, Zn and Mo element content, is 1-6 g / L; and the concentration of the inorganic phosphate, based on the P element content, is... The total concentration is 0.5-3 g / L; the concentration of the silicon-containing oligomer and / or modified silica sol, based on the Si element content, is 0.005-0.3 g / L; preferably, the concentration of the water-soluble salt of titanium is 0.8-2 g / L, the total concentration of the water-soluble salts of manganese, zinc and molybdenum is 2-4 g / L, the concentration of the inorganic phosphate is 0.8-2 g / L, and the concentration of the silicon-containing oligomer and / or modified silica sol is 0.025-0.2 g / L; preferably, the total content of the surface wetting agent, such as polyethylene glycol and / or propylene glycol, is 0.5-5 g / L.

15. The chromium-free passivation solution as described in claim 14, characterized in that, The water-soluble salt of titanium is selected from at least one of potassium fluorotitanate, ammonium fluorotitanate, potassium titanium oxalate, and titanium oxysulfate; the inorganic phosphate is selected from at least one of potassium dihydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, and sodium metaphosphate; the silicon-containing oligomer is selected from silane oligomers; the water-soluble salt of manganese is selected from at least one of manganese dihydrogen phosphate, potassium permanganate, and manganese nitrate; the water-soluble salt of zinc is selected from at least one of zinc dihydrogen phosphate, zinc sulfate, and zinc nitrate; the water-soluble salt of molybdenum is selected from at least one of sodium molybdate and ammonium molybdate; and / or, the pH value of the chromium-free passivation solution is 2-6; preferably, the modified silica sol is an epoxysilane-modified silica sol or an aminosilane-modified silica sol; preferably, the silane oligomer is obtained by polymerization of tetramethylsilane and glycidyl etheroxypropylcyclotetrasiloxane, or the silane oligomer is obtained by polymerization of trimethoxysilane and a sulfur-containing silane coupling agent.

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