PSA electrotinning insoluble anode system and production method of electrotinning plate

Abstract

The invention discloses a PSA electrotinning insoluble anode system and a production method of an electrotinning plate, and relates to the technical field of electrotinning. The PSA tin electroplating insoluble anode system comprises an electroplating additive which is composed of benzotriazole, N-oleoyl sarcosine, S-carboxyethyl thiosuccinic acid and sodium citrate. The problems of serious black ash and poor coating performance of an electroplated tin plate product are solved, the tin plating stability of a plating solution in an electroplating bath is improved, the black ash on the surface of the electroplated tin plate product can be effectively reduced, the requirements of low black ash and high adhesive force on the surface of an electroplated tin plate of a PSA (Pressure Swing Adsorption) electroplated tin insoluble anode system are met, and the service life of the electroplated tin plate is prolonged. The electroplated tin plate produced through the PSA electroplated tin insoluble anode system is bright and clean in plating layer surface, and after the tin layer surface with the thickness of 8.4 g / m < 2 > and below is wiped through test paper, the reduction percentage of the test paper whiteness caused by black ash is smaller than or equal to 10%.

Description

Technical Field

[0001] The present invention relates to the technical field of electroplating tin, and particularly to a PSA electroplating tin insoluble anode system and a production method of electroplated tinplate. Background Art

[0002] Electroplated tinplate generally has an oil coating layer, a passivation layer, a tin oxide layer, a pure tin coating layer, an iron - tin alloy layer (FeSn2), etc. It is beautiful and non - toxic, has excellent corrosion resistance to dilute acids, alkalis, salts and organic substances, as well as excellent weldability, stamping property and appropriate strength, and is easy to coat and print. Therefore, electroplated tinplate is widely used in different forms of articles, such as the packaging of food, beverages, chemicals, paints, sprays and the manufacture of various utensils.

[0003] In the production process of electroplated tinplate, the strip steel will be degreased, electroplated with tin, and then subjected to soft melting, quenching, passivation and oil coating treatments. During the electroplating of tin, black granular substances, namely black ash, will be dispersed on the surface of the coating. The existence of black ash seriously affects the appearance of the tin - plated steel sheet and the adhesion between the tin - plated layer and the paint film. Electroplating, soft melting and passivation are the processes most likely to produce black ash. The main component of black ash is tin dioxide, and its content accounts for about 50%. Experiments show that stannous oxide with a low valence will be produced during soft melting and cathodic electrolytic passivation, and a large amount of oxygen will be precipitated when the insoluble anode is in working state. Under the condition of acidic plating solution, the oxygen precipitated from the insoluble anode can easily oxidize Sn in stannous oxide 2+ to the insoluble substance SnO2. The higher the temperature of the plating solution, the faster the speed of Sn 2+ being oxidized to the insoluble substance SnO2. During the electroplating process, SnO2 will enter the coating, thus producing black ash. Black ash often reduces the whiteness by more than 30%, which not only affects the surface appearance of the tin - plated plate, but also significantly reduces the adhesion between the coating and the tin - plated layer. Therefore, how to reduce the black ash on the tin - plated plate is an urgent problem to be solved at present.

[0004] In the prior art, the methods adopted to solve the black ash problem of tinplate mainly include online wiping of the strip steel surface. For example, the Chinese invention application with the application number CN202410959041.7 provides a device and method for cleaning black ash on the tin - plated surface. The cleaning device is composed of a black - ash wiping mechanism and a black - ash wiping bracket to perform online wiping on the strip steel surface to clean the black ash on the strip steel surface. This method is a post - treatment of the product, increasing the process and equipment investment. Summary of the Invention

[0005] To overcome the deficiencies of the above - mentioned technologies, the purpose of the present invention is to provide a PSA electroplating tin insoluble anode system and a production method of electroplated tinplate, to solve the problems of serious black ash and poor coating performance of electroplated tinplate products, and to meet the requirements of low black ash and high adhesion on the surface of electroplated tinplate of the PSA electroplating tin insoluble anode system, 8.4g / m2 For electrolytic tinplate products with a tin coating thickness of 2 and below, the percentage reduction in the whiteness of the test paper caused by surface blackening and greying is ≤ 10%.

[0006] To achieve the above object, the technical solution adopted in the present invention is as follows:

[0007] An electroplating additive for a PSA electroplating tin insoluble anode system, characterized in that it includes benzotriazole, N - oleoyl sarcosine, S - carboxyethyl thiosuccinic acid, and sodium citrate.

[0008] As a preferred solution, the concentrations of the components in the electroplating additive in the PSA electroplating tin insoluble anode system are as follows: benzotriazole 0.1 - 0.3 g / L, N - oleoyl sarcosine 0.1 - 0.3 g / L, S - carboxyethyl thiosuccinic acid 0.2 - 0.4 g / L, and sodium citrate 0.4 - 0.8 g / L.

[0009] A PSA electroplating tin insoluble anode system, characterized in that it includes the above electroplating additive; it also includes stannous ions, phenol sulfonic acid, α - naphthol polyoxyethylene ether, α - naphthol sulfonic acid polyoxyethylene ether, and a solvent.

[0010] Furthermore, the average degree of polymerization NEO of the ethoxy groups in the α - naphthol polyoxyethylene ether is 10; the average degree of polymerization NEO of the ethoxy groups in the α - naphthol sulfonic acid polyoxyethylene ether is 6, and it contains about 40% of unsulfonated EN - 6.

[0011] Furthermore, the concentrations of the components in the PSA electroplating tin insoluble anode system are as follows: stannous ions 25 - 30 g / L, phenol sulfonic acid 15 - 20 g / L, α - naphthol polyoxyethylene ether 5 - 7 g / L, α - naphthol sulfonic acid polyoxyethylene ether 2 - 4 g / L, benzotriazole 0.1 - 0.3 g / L, N - oleoyl sarcosine 0.1 - 0.3 g / L, S - carboxyethyl thiosuccinic acid 0.2 - 0.4 g / L, and sodium citrate 0.4 - 0.8 g / L.

[0012] Furthermore, the stannous ions are from stannous sulfate; the solvent is water.

[0013] A production method of electrolytic tinplate includes the following processes: tin - plated substrate → degreasing → electroplating tin → soft melting → quenching in water → passivation → oiling, to obtain the electrolytic tinplate product, characterized in that: the electroplating tin process uses the above PSA electroplating tin insoluble anode system or a PSA electroplating tin insoluble anode system containing the above electroplating additive.

[0014] As a preferred solution, in the electroplating tin process, the temperature of the electroplating bath solution is controlled within the range of 26 ± 4 °C.

[0015] As a preferred solution, in the tin plating process, the current density is controlled within the range of 10 - 15 A / dm 2 range.

[0016] As a preferred solution, the detection of black ash on the surface of the tin layer of the tinplate product is measured by comparing the change in the whiteness value of the test paper before and after wiping the surface of the tin layer with the test paper.

[0017] Furthermore, the percentage reduction in the whiteness value of the surface of the test paper caused by black ash on the surface of the tin layer of the tinplate is ≤ 10%.

[0018] In the present invention, the functions of the components of the electroplating additive formulation for the PSA tin plating insoluble anode system are as follows:

[0019] Stannous sulfate is the main salt, providing tin ions. Phenolsulfonic acid (PSA), α-naphthol polyoxyethylene ether (EN), and α-naphthol sulfonic acid polyoxyethylene ether (ENSA) are organic additives, and their main functions are to improve the stability of the tin plating solution, increase the electroplating efficiency, and improve the surface quality of the tinplate. Benzotriazole easily complexes divalent iron ions, divalent tin ions, and tetravalent tin ions in the electroplating bath, preventing dissolved oxygen from oxidizing divalent tin ions. The tetravalent tin ions are complexed to prevent the formation of SnO2 from tetravalent tin ions. N-oleoyl sarcosine and S-carboxyethyl thiosuccinic acid play solubilizing and wetting roles, increasing the activation polarization during the tin electrodeposition process, and thus changing the tin electrodeposition rate. Sodium citrate reduces the hardness of the water quality and further purifies the water quality in the bath.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The present invention discloses a PSA tin plating insoluble anode system and its electroplating additive, which can improve the tin plating stability of the plating solution in the electroplating bath, effectively reduce the black ash on the surface of the tinplate product, meet the requirements of low black ash and high adhesion on the surface of the tinplate for the PSA tin plating insoluble anode system. The surface of the tinplate coating produced by the PSA tin plating insoluble anode system of the present invention is bright and clean. The percentage reduction in the whiteness of the test paper caused by black ash after wiping the surface of the tin layer with a thickness of 8.4 g / m 2 and below by the test paper is ≤ 10%. Detailed Embodiments

[0022] In order to better explain the present invention, the main content of the present invention is clarified below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments only.

[0023] An electroplating additive for a PSA electroplated tin insoluble anode system provided by the present invention, the concentrations of each component in the PSA electroplated tin insoluble anode system are as follows: benzotriazole 0.1 - 0.3 g / L, N - oleoyl sarcosine 0.1 - 0.3 g / L, S - carboxyethyl thiosuccinic acid 0.2 - 0.4 g / L, sodium citrate 0.4 - 0.8 g / L.

[0024] The present invention also provides a PSA electroplated tin insoluble anode system, including the above electroplating additive. The components and their concentrations in this PSA electroplated tin insoluble anode system are as follows: stannous ion 25 - 30 g / L, phenol sulfonic acid 15 - 20 g / L, α - naphthol polyoxyethylene ether 5 - 7 g / L, α - naphthol sulfonic acid polyoxyethylene ether 2 - 4 g / L, benzotriazole 0.1 - 0.3 g / L, N - oleoyl sarcosine 0.1 - 0.3 g / L, S - carboxyethyl thiosuccinic acid 0.2 - 0.4 g / L, sodium citrate 0.4 - 0.8 g / L.

[0025] Among them, the average degree of polymerization NEO of ethoxy groups of α - naphthol polyoxyethylene ether = 10; the average degree of polymerization NEO of ethoxy groups of α - naphthol sulfonic acid polyoxyethylene ether = 6, and it contains about 40% of unsulfonated EN - 6. The stannous ion comes from stannous sulfate; the solvent is water.

[0026] The present invention also provides a production method of electroplated tin plate, including the following processes: tin - plated substrate → degreasing → electroplating tin → soft melting → quenching in water → passivation → oiling, to obtain the electroplated tin plate product; the electroplating tin process uses the above - mentioned PSA electroplated tin insoluble anode system. When electroplating tin, the temperature of the electroplating bath solution is controlled within the range of 26 ± 4 °C, and the current density is controlled within the range of 10 - 15 A / dm 2 range.

[0027] The content of the present invention is further described below through examples and comparative examples.

[0028] In the example, the production method of electroplated tin plate uses the method of the present invention. The difference between the production method of electroplated tin plate in the comparative example and that in the example lies in the different components of the PSA electroplated tin insoluble anode system and some process parameters. The components and concentrations of the PSA electroplated tin insoluble anode system in the example and the comparative example are shown in Table 1, and the process parameters are shown in Table 2. The whiteness of the electroplated tin plate products in the example and the comparative example is tested.

[0029] The whiteness test method in the examples and comparative examples includes the following steps: Take a blank test paper and measure the whiteness value of the blank test paper; then use the blank test paper to wipe the electroplated tinplate product and measure the whiteness value of the test paper after wiping; take the average value of the three tests; compare the whiteness test results before and after wiping the test paper. The higher the percentage decrease in the whiteness value, the higher the black ash content. The whiteness test refers to GB / T 13448-2006. The whiteness test results are shown in Table 3 and Table 4. This method can quantitatively measure the black ash degree on the surface of electroplated tinplate products by comparing the whiteness values of the test paper. The test process is scientific and reasonable, and the results are objective, accurate, and highly feasible.

[0030] Table 1: Formulation of the PSA electroplated tin insoluble anode system

[0031]

[0032] Table 2: Electroplating process parameters

[0033]

[0034] Table 3: Black ash detection results of the examples

[0035]

[0036] Table 4: Black ash detection results of the comparative examples

[0037]

[0038] From the product performance test results, it can be seen that for the products produced by electroplating with the electroplating additives in the present invention method in Examples 1 to 5, the surface is bright and clean, and the percentage decrease in whiteness of the test paper after wiping the tin layer with a tin layer thickness of 8.4 g / m 2 and below is ≤ 10% compared with that before wiping.

[0039] Compared with Example 1, in Comparative Example 1, the bath temperature is higher than the range of the present invention, and the percentage decrease in the whiteness value of the product obtained reaches 21.87. Compared with Example 2, in Comparative Example 2, the current density exceeds the range of the present invention, and the percentage decrease in the whiteness value of the product obtained is 10.57 more than that in Example 2. Comparative Examples 3 and 4 are the electroplating schemes using the anode system without adding the electroplating additives of the present invention in the prior art. The main components of Comparative Example 3 are the same as those of Example 3, and those of Comparative Example 4 are the same as those of Example 4. The bath temperature and current density exceed the range of the present invention, and the percentage decrease in the whiteness value of the product obtained is significantly increased compared with that in the examples. In Comparative Examples 5 to 12, the electroplating additives are respectively the schemes where a single component exceeds the range of the present invention. Compared with the examples, the percentage decrease in the whiteness value of the product is significantly higher, that is, the black ash content is significantly more than that in the examples.

[0040] In summary, compared with the prior art, the solution of the present invention can effectively reduce the black ash on the surface of electroplated tinplate products, meeting the requirements of low black ash and high adhesion on the surface of electroplated tinplate in the PSA electroplated tin insoluble anode system.

Claims

1. A plating additive for PSA electroplating tin insoluble anode system, characterized in that: Including benzotriazole, N-oleoyl sarcosine, S-carboxyethyl sulfosuccinic acid, and sodium citrate.

2. The electroplating additive according to claim 1, characterized in that: The concentrations of the components in the electroplating additive in the PSA electroplating tin insoluble anode system are as follows: benzotriazole 0.1-0.3 g / L, N-oleoyl sarcosine 0.1-0.3 g / L, S-carboxyethyl sulfosuccinic acid 0.2-0.4 g / L, and sodium citrate 0.4-0.8 g / L.

3. A PSA electroplating tin insoluble anode system, characterized in that: The electroplating additive comprises the electroplating additive according to claim 1 or 2; and further comprises stannous ions, phenol sulfonic acid, α-naphthol polyoxyethylene ether, α-naphthol sulfonic acid polyoxyethylene ether and a solvent.

4. The PSA electroplating tin insoluble anode system according to claim 3, characterized in that: The concentrations of the components in the PSA electroplating tin insoluble anode system are as follows: 25-30 g / L of stannous ions, 15-20 g / L of phenolsulfonic acid, 5-7 g / L of α-naphthol polyoxyethylene ether, 2-4 g / L of α-naphthol sulfonic acid polyoxyethylene ether, 0.1-0.3 g / L of benzotriazole, 0.1-0.3 g / L of N-oleoyl sarcosine, 0.2-0.4 g / L of S-carboxyethyl sulfosuccinic acid, and 0.4-0.8 g / L of sodium citrate.

5. The PSA electroplating tin insoluble anode system according to claim 3 or 4, characterized in that: The stannous ions are derived from stannous sulfate.

6. A method for producing an electroplated tinplate, comprising the following steps: tin-plated substrate → degreasing → electroplating tin → soft melting → quenching → passivation → oiling, to obtain the electroplated tinplate product, characterized in that: The electrotinning process adopts the electroplating additive of the PSA electrotinning insoluble anode system according to claim 1 or 2 or the PSA electrotinning insoluble anode system according to any one of claims 3 to 5.

7. The production method according to claim 6, characterized in that: In the tin electroplating process, the temperature of the plating solution in the electroplating tank is controlled within the range of 26±4°C.

8. The production method according to claim 6, characterized in that: In the electroplating tinning process, the current density of the electroplating tank is controlled at 10-15A / dm 2 scope.

9. The production method according to any one of claims 6 to 8, characterized in that: The black ash detection on the surface of the tin layer of the electroplated tinplate product is measured by wiping the surface of the tin layer with a test paper and comparing the change in the whiteness value of the test paper before and after wiping.

10. The production method according to claim 9, characterized in that: The black gray on the surface of the tin layer of the electroplated tinplate reduces the whiteness value of the test paper surface by a percentage of ≤10%.

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