Additives for PSA tin-plating insoluble anode systems and methods for producing tin-plated sheets

Abstract

This invention belongs to the field of electroplating technology, specifically relating to an additive for a PSA tin-insoluble anode system and a method for producing tin-plated sheets. The additive is obtained by uniformly mixing sodium dimercaprolactone sulfonate, sodium gluconate, sodium bicarbonate, and sodium carbonate. When preparing tin-plated sheets, adding a certain proportion of this additive to the quenching tank can result in a tin oxide film on the surface of the quenched tin-plated sheet ≤1 mC / cm². 2 Next, the surface of the tin-plated plate prepared after quenching is passivated. The passivation film generated on the surface of the tin-plated plate can improve the corrosion resistance and adhesion of the tin-plated plate.

Description

Technical Field

[0001] This invention belongs to the field of electroplating technology, specifically relating to additives for PSA tin-insoluble anode systems and methods for producing tin-plated plates, and particularly to tin oxide films with a thickness of ≤1 mC / cm for PSA tin-insoluble anode systems. 2 Additives and production methods for tin-plated sheets. Background Technology

[0002] Electroplated tinplate typically consists of an oil coating, passivation layer, tin oxide layer, pure tin plating, and an iron-tin alloy layer (FeSn2). It is aesthetically pleasing, non-toxic, and possesses excellent resistance to corrosion from dilute acids, alkalis, salts, and organic substances. It also exhibits good weldability, stamping properties, and suitable strength, and is easy to coat and print on. Therefore, electroplated tinplate is widely used in the packaging of various types of goods, such as food, beverages, chemicals, paints, and aerosols, as well as in the manufacture of various utensils.

[0003] In the production process of tinplate, the strip steel undergoes degreasing, tin plating, softening, quenching, passivation, and oiling. Tinplate, when subjected to high temperatures or stored in air with appropriate humidity, develops a tin oxide film, including SnO and SnO2. SnO is formed at temperatures above 100°C, and grows rapidly near the melting point of tin (232°C) during softening. SnO is unstable and does not improve the corrosion resistance of the tinplate; in fact, corrosion resistance decreases as this oxide film increases. SnO2 is formed at temperatures below 100°C. While it grows more easily at higher temperatures, its growth rate is much slower than that of SnO. SnO2 is very stable, and corrosion resistance increases with the increase of this oxide film. When the tinplate is softened and heated, a tin oxide film forms on its surface. This tin oxide film not only discolors the tinplate surface, reducing its corrosion resistance and solderability, but also significantly reduces the adhesion between the coating and the tin plating layer. To overcome the drawbacks caused by tin oxide film, the surface of tin-plated plates must be passivated. The most common method is to generate a chromate passivation film by treating with sodium dichromate electrolyte. This passivation film can greatly improve corrosion resistance. However, when there is a lot of thick tin oxide film on the surface of the tin-plated plate, the passivation effect is greatly reduced, and the passivation film may even fall off quickly. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing electroplated tin sheets, which tend to form a thick tin oxide film on the surface during production or use, thus degrading the performance of the tin-plated sheets. Therefore, this invention proposes an additive for PSA tin-plating insoluble anode systems and a method for producing tin-plated sheets. This additive consists of specific components. Adding the additive described in this invention to the quenching process in the preparation of electroplated tin sheets can destabilize colloids and suspended solids, accelerating their sedimentation. Simultaneously, the specific components in the additive can undergo a complexation reaction with cations in the quenching tank, thereby reducing the hardness of the water in the quenching tank and ensuring that the tin oxide film on the surface of the quenched tin-plated sheet is ≤1 mC / cm². 2 The surface of the electroplated tin plate prepared by quenching water according to the present invention is subjected to passivation treatment. The passivation film generated on the surface of the electroplated tin plate can improve the corrosion resistance and adhesion of the electroplated tin plate.

[0005] The first aspect of the present invention provides an additive component for a PSA tin-insoluble anode system, the additive component comprising sodium dimercaptopropanesulfonate, sodium gluconate, sodium bicarbonate and sodium carbonate.

[0006] Preferably, the additive components, by weight of 100%, consist of 5-10% sodium dimercaptopropanesulfonate, 5-10% sodium gluconate, 40-50% sodium bicarbonate, and 40-50% sodium carbonate.

[0007] More preferably, the additive components, based on a total weight of 100%, consist of 5-8% sodium dimercaptopropanesulfonate, 5-6% sodium gluconate, 40-42% sodium bicarbonate, and 44-50% sodium carbonate.

[0008] The second aspect of the present invention provides an additive for a PSA tin-insoluble anode system, wherein the additive components described above for a PSA tin-insoluble anode system are mixed evenly to obtain the additive for a PSA tin-insoluble anode system.

[0009] The third aspect of this invention provides a method for preparing tin-plated sheets using the additive described above for the PSA tin-plating insoluble anode system. The method includes: sequentially degreasing, electroplating, remelting, quenching, passivating, and oiling the tin-plated substrate, wherein, during the quenching process, the additive for the PSA tin-plating insoluble anode system is added to the quenching tank, and the content of the additive is 0.6-1.0% based on the weight of the liquid in the quenching tank as 100%.

[0010] Preferably, the content of the additive is 0.7-0.8% based on the weight of the liquid in the quenching tank as 100%.

[0011] Preferably, the electroplating solution used in the electroplating process has the following composition: stannous sulfate 25-30 g / L, phenol sulfonic acid 15-20 g / L, α-naphthol polyoxyethylene ether 5-7 g / L, and α-naphthol sulfonic acid polyoxyethylene ether 2-4 g / L.

[0012] More preferably, the electroplating solution used in the electroplating process has the following composition: stannous sulfate 26-28 g / L, phenol sulfonic acid 16-18 g / L, α-naphthol polyoxyethylene ether 5-5.5 g / L, and α-naphthol sulfonic acid polyoxyethylene ether 3-3.5 g / L.

[0013] Preferably, the temperature of the electroplating solution used in the electroplating process is 32–38°C, and the current density is 10–15 A / dm³. 2 .

[0014] Preferably, during the passivation process, the passivation system has the following characteristics: sodium dichromate concentration of 23-27 g / L, pH value of 4.2-4.6, and temperature of 41-43℃.

[0015] The additive for the PSA tin-plating insoluble anode system and the method for producing tin-plated plates described in this invention have at least the following beneficial effects:

[0016] (1) When tin-plated sheets are heated by soft melting and then placed in a quenching tank for cooling and quenching, the quenching tank often contains colloids and suspended solids, forming a complex integrated system. These colloids and suspended solids easily cover the plating surface, forming a thick tin oxide film. In this invention, sodium dimercaptopropanesulfonate in the additive has a strong adsorption effect on colloidal particles in the water, destabilizing the colloids and suspended solids, accelerating the sedimentation process of the colloids and suspended solids, and inhibiting impurities from covering the plating surface. At the same time, sodium gluconate in the additive can undergo a complexation reaction with cations in the quenching tank, reducing the hardness of the water and further purifying the water in the quenching tank, ensuring the cleanliness of the plating surface. Sodium bicarbonate and sodium carbonate have an alkaline cleaning effect, and at the same time, sodium bicarbonate and sodium carbonate form a buffer solution system to ensure pH stability during cleaning. Adding a certain proportion of sodium dimercaptopropanesulfonate, sodium gluconate, sodium bicarbonate, and sodium carbonate during the quenching process can make the surface of the electroplated tin sheet bright and clean, with a tin oxide film ≤1mC / cm. 2 ;

[0017] (2) In a preferred embodiment, adding 0.7–0.8% of an additive for the PSA tin-insoluble anode system to the quenching tank, while rationally controlling the composition and content of the electroplating solution, can result in a tin oxide film on the surface of the tin-plated plate with a thickness of ≤0.7 mC / cm². 2 ;

[0018] (3) The additives of the present invention for the PSA tin-plating insoluble anode system are safe and environmentally friendly, do not produce strong irritating odors, and can keep the water quality in the quenching tank stable without affecting the normal process of tin plating. Detailed Implementation

[0019] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0020] The first aspect of this invention provides an additive component for a PSA tin-plating insoluble anode system, comprising sodium dimercaptopropanesulfonate, sodium gluconate, sodium bicarbonate, and sodium carbonate. Adding the additive component described herein during the quenching process before passivation in the preparation of the tin-plated plate can result in a tin oxide film on the surface ≤1 mC / cm². 2 This has extremely important practical significance for the performance of tin-plated sheets.

[0021] Sodium dimercaptopropane sulfonate acts as an adsorbent for suspended solids in water, stabilizing and controlling impurities and inhibiting their deposition on the coating surface. The more suspended impurities on the coating surface, the higher the water content and the greater the oxygen content in the thin liquid, leading to accelerated oxidation of the coating surface. In the production process of tinplate electroplating, when the tinplate is heated through a soft melt and then placed in a quenching tank for cooling, the quenching tank often contains colloids and suspended solids, forming a complex system. Sodium dimercaptopropane sulfonate has a strong adsorption effect on colloidal particles in water, destabilizing colloids and suspended solids and accelerating their sedimentation. Sodium gluconate complexes cations in the quenching tank, such as calcium ions, reducing water hardness and further purifying the water, ensuring a clean coating surface. Sodium bicarbonate and sodium carbonate have alkaline cleaning properties, and simultaneously form a buffer solution system to ensure pH stability during cleaning.

[0022] In the additive components for the PSA tin-insoluble anode system described in this invention, in a specific embodiment, based on 100% of the total weight of the additive components, it comprises 5-10% sodium dimercaptopropanesulfonate, for example, 5%, 7%, 8%, or 10%; 5-10% sodium gluconate, for example, 5%, 6%, or 10%; 40-50% sodium bicarbonate, for example, 40%, 41%, 42%, 43%, or 50%; and 40-50% sodium carbonate, for example, 40%, 43%, 44%, or 50%. In a preferred embodiment, based on 100% of the total weight of the additive components, it comprises 5-8% sodium dimercaptopropanesulfonate, 5-6% sodium gluconate, 40-42% sodium bicarbonate, and 44-50% sodium carbonate.

[0023] The second aspect of this invention provides an additive for a PSA tin-insoluble anode system. The additive components described above for a PSA tin-insoluble anode system are mixed evenly. Specifically, sodium dimercaptopropanesulfonate, sodium gluconate, sodium bicarbonate, and sodium carbonate are mixed evenly in a certain weight ratio to obtain the additive for a PSA tin-insoluble anode system.

[0024] A third aspect of this invention provides a method for preparing tin-plated sheets using the additive described above for the PSA tin-plating insoluble anode system. The method includes: sequentially degreasing, electroplating, remelting, quenching, passivating, and oiling the tin-plated substrate. During the quenching process, the additive for the PSA tin-plating insoluble anode system is added to the quenching tank. The additive content is 0.6% to 1.0% based on the weight of the liquid in the quenching tank (100%). Specifically, the additive content can be 0.6%, 0.7%, 0.8%, 0.9%, or 1.0%.

[0025] In the production method for preparing tin-plated plates according to the present invention, in a preferred embodiment, the content of the additive is 0.7-0.8% based on 100% of the weight of the liquid in the quenching tank, which can make the surface tin oxide film ≤0.7mC / cm 2 The tin oxide film is relatively thin. After passivation treatment, a stable and dense passivation film is generated on the surface of the plating layer. The surface of the plating layer is not easy to discolor or turn yellow, thereby improving the corrosion resistance of the surface of the electroplated tin plate and the adhesion between the user's coating film and the tin plating layer.

[0026] In the production method for preparing tin-plated plates described in this invention, in a specific embodiment, the composition of the electroplating solution used in the electroplating process is as follows: stannous sulfate (providing tin ions) 25-30 g / L, for example, 25 g / L, 26 g / L, 27 g / L, 28 g / L, or 30 g / L; phenol sulfonic acid (PSA) 15-20 g / L, for example, 15 g / L, 16 g / L, 17 g / L, 18 g / L, or 20 g / L; α-naphthol polyoxyethylene ether (EN, average degree of polymerization NEO = 10) 5-7 g / L, for example, 5 g / L, 5.5 g / L, 6 g / L, or 7 g / L; α-naphthol sulfonic acid polyoxyethylene ether (ENSA, average degree of polymerization NEO = 6, containing approximately 40% unsulfonated EN-6) 2-4 g / L, for example, 2 g / L, 3 g / L, 3.5 g / L, or 4 g / L.

[0027] In a preferred embodiment, the electroplating solution used in the electroplating process comprises: stannous sulfate 26-28 g / L, phenol sulfonic acid 16-18 g / L, α-naphthol polyoxyethylene ether 5-5.5 g / L, and α-naphthol sulfonic acid polyoxyethylene ether 3-3.5 g / L.

[0028] In the production method for preparing tin-plated plates described in this invention, in a specific embodiment, the temperature of the electroplating bath is controlled at 32–38°C, and the current density is controlled at 10–15 A / dm². 2 .

[0029] In the production method for preparing tin-plated plates described in this invention, in a specific embodiment, during the passivation process, the passivation system has the following characteristics: the concentration of sodium dichromate is 23-27 g / L, the pH value is 4.2-4.6, and the temperature is 41-43℃.

[0030] In the production method for preparing tin-plated plates described in this invention, in a specific embodiment, the degreasing process of the tin-plated substrate is described as electrolytic cleaning: NaOH 35±5 g / L, temperature 50±5℃, and current density 20±10 A / dm³. 2 The remelting process for the tin-plated sheet after electroplating is a combined remelting mode using resistance remelting and induction remelting. The induction remelting temperature rise is set to 80℃, and resistance remelting is used for residual heating to melt the tin plating layer on the strip surface. The remelting temperature is 232~300℃. The passivated tin-plated sheet is then coated with oil using electrostatic oil, which is dioctyl sebacate (DOS oil), and the oil film thickness is 2~8mg / m. 2 .

[0031] Unless otherwise specified, the test methods or experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are obtained from conventional commercial sources or prepared by conventional methods.

[0032] Example 1

[0033] Additive for PSA tin-insoluble anode system: Weigh 5% sodium dimercaptopropanesulfonate, 5% sodium gluconate, 50% sodium bicarbonate and 40% sodium carbonate, mix these raw material components evenly to obtain additive A-1.

[0034] The production method for preparing tin-plated sheets involves sequentially degreasing, electroplating, remelting, quenching, passivation, and oiling of the tin-plating substrate. The electroplating solution comprises: 25 g / L tin ions (provided by stannous sulfate), 15 g / L PSA (phenol sulfonic acid), 5 g / L EN, and 4 g / L ENSA. The electroplating bath temperature is controlled at 32℃, and the current density is controlled at 15 A / dm³. 2 ;

[0035] During the quenching process, A-1 is added to the quenching tank, and the content of A-1 is 0.6% based on the weight of the liquid in the quenching tank as 100%. During the passivation process, the passivation system is as follows: the concentration of sodium dichromate is 25 g / L, the pH value is 4.4, and the temperature is 42℃.

[0036] The final tin-plated sheet produced has a surface tin oxide film of 0.95 mC / cm². 2 The tin-plated sheet will not change color or turn yellow within 6 months of leaving the factory. The adhesion level between the user's coating film and the tin plating layer is ≤2, which fully meets the user's requirements.

[0037] Example 2

[0038] Additive for PSA tin-insoluble anode system: Weigh 7% sodium dimercaptopropanesulfonate, 10% sodium gluconate, 43% sodium bicarbonate and 40% sodium carbonate, and mix these raw material components evenly to obtain additive A-2.

[0039] The production method for preparing tin-plated sheets involves sequentially degreasing, electroplating, remelting, quenching, passivation, and oiling of the tin-plating substrate. The electroplating solution comprises: 30 g / L tin ions (provided by stannous sulfate), 20 g / L PSA (phenol sulfonic acid), 7 g / L EN, and 2 g / L ENSA. The electroplating bath temperature is controlled at 38℃, and the current density is controlled at 10 A / dm³. 2 ;

[0040] During the quenching process, A-2 is added to the quenching tank, and the content of A-2 is 1.0% based on the weight of the liquid in the quenching tank as 100%. During the passivation process, the passivation system is as follows: the concentration of sodium dichromate is 23 g / L, the pH value is 4.2, and the temperature is 41℃.

[0041] The final electroplated tin plate has a surface tin oxide film of 0.92 mC / cm². 2 The tin-plated sheet will not change color or turn yellow within 6 months of leaving the factory. The adhesion level between the user's coating film and the tin plating layer is ≤2, which fully meets the user's requirements.

[0042] Example 3

[0043] Additive for PSA tin-insoluble anode system: Weigh 10% sodium dimercaptopropanesulfonate, 6% sodium gluconate, 41% sodium bicarbonate and 43% sodium carbonate, and mix these raw material components evenly to obtain additive A-3.

[0044] The production method for preparing tin-plated sheets involves sequentially degreasing, electroplating, remelting, quenching, passivation, and oiling of the tin-plating substrate. The electroplating solution comprises: 27 g / L tin ions (provided by stannous sulfate), 17 g / L PSA (phenol sulfonic acid), 6 g / L EN, and 3 g / L ENSA. The electroplating bath temperature is controlled at 35°C, and the current density is controlled at 13 A / dm³. 2 ;

[0045] During the quenching process, A-3 is added to the quenching tank, and the content of A-3 is 0.9% based on the weight of the liquid in the quenching tank as 100%. During the passivation process, the passivation system is as follows: the concentration of sodium dichromate is 27 g / L, the pH value is 4.6, and the temperature is 43℃.

[0046] The final electroplated tin plate has a surface tin oxide film of 0.94 mC / cm². 2 The tin-plated sheet will not change color or turn yellow within 6 months of leaving the factory. The adhesion level between the user's coating film and the tin plating layer is ≤2, which fully meets the user's requirements.

[0047] Example 4

[0048] Additive for PSA tin-insoluble anode system: Weigh 5% sodium dimercaptopropanesulfonate, 5% sodium gluconate, 40% sodium bicarbonate and 50% sodium carbonate, and mix these raw material components evenly to obtain additive A-4.

[0049] The production method for preparing tin-plated sheets involves sequentially degreasing, electroplating, remelting, quenching, passivation, and oiling of the tin-plating substrate. The electroplating solution comprises: 28 g / L tin ions (provided by stannous sulfate), 16 g / L PSA (phenol sulfonic acid), 5.5 g / L EN, and 3.5 g / L ENSA. The electroplating bath temperature is controlled at 33℃, and the current density is controlled at 14 A / dm³. 2 ;

[0050] During the quenching process, A-4 is added to the quenching tank, and the content of A-4 is 0.7% based on the weight of the liquid in the quenching tank as 100%. During the passivation process, the passivation system is as follows: the concentration of sodium dichromate is 26 g / L, the pH value is 4.5, and the temperature is 42.5℃.

[0051] The final electroplated tin plate has a surface tin oxide film of 0.87 mC / cm². 2 The tin-plated sheet will not change color or turn yellow within 6 months of leaving the factory. The adhesion level between the user's coating film and the tin plating layer is ≤2, which fully meets the user's requirements.

[0052] Example 5

[0053] Additive for PSA tin-insoluble anode system: Weigh 8% sodium dimercaptopropanesulfonate, 6% sodium gluconate, 42% sodium bicarbonate and 44% sodium carbonate, and mix these raw material components evenly to obtain additive A-5.

[0054] The production method for preparing tin-plated sheets involves sequentially degreasing, electroplating, remelting, quenching, passivation, and oiling of the tin-plating substrate. The electroplating solution comprises: 26 g / L tin ions (provided by stannous sulfate), 18 g / L PSA (phenol sulfonic acid), 5 g / L EN, and 3 g / L ENSA. The electroplating bath temperature is controlled at 36℃, and the current density is controlled at 12 A / dm³. 2 ;

[0055] During the quenching process, A-5 is added to the quenching tank, and the content of A-5 is 0.8% based on the weight of the liquid in the quenching tank as 100%. During the passivation process, the passivation system is as follows: the concentration of sodium dichromate is 24 g / L, the pH value is 4.3, and the temperature is 42℃.

[0056] The final electroplated tin plate has a surface tin oxide film of 0.89 mC / cm². 2 The tin-plated sheet will not change color or turn yellow within 6 months of leaving the factory. The adhesion level between the user's coating film and the tin plating layer is ≤2, which fully meets the user's requirements.

[0057] Comparative Example 1

[0058] The process was carried out as described in Example 1, except that the additive was not added. The final electroplated tin plate produced had a surface tin oxide film of 2.1 mC / cm². 2 Within three months of leaving the factory, some of the tin-plated sheets may turn yellow or discolor. Sometimes the adhesion level between the user's coating film and the tin plating layer may reach level 3, failing to meet the user's requirements.

[0059] Comparative Example 2

[0060] The process was carried out as described in Example 2, except that the additive was not added. The final electroplated tin plate produced had a surface tin oxide film of 2.7 mC / cm². 2 Within three months of leaving the factory, some of the tin-plated sheets may turn yellow or discolor. Sometimes the adhesion level between the user's coating film and the tin plating layer may reach level 3, failing to meet the user's requirements.

[0061] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An additive component for a PSA tin-insoluble anode system, characterized in that, The additive components include sodium dimercaptopropanesulfonate, sodium gluconate, sodium bicarbonate, and sodium carbonate; Based on the total weight of the additive components (100%), it consists of 5-10% sodium dimercaptopropanesulfonate, 5-10% sodium gluconate, 40-50% sodium bicarbonate, and 40-50% sodium carbonate.

2. The additive component for the PSA tin-insoluble anode system according to claim 1, characterized in that, Based on the total weight of the additive components (100%), it consists of 5-8% sodium dimercaptopropanesulfonate, 5-6% sodium gluconate, 40-42% sodium bicarbonate, and 44-50% sodium carbonate.

3. An additive for use in PSA tin-insoluble anode systems, characterized in that, The additive components for the PSA tin-insoluble anode system as described in claim 1 or 2 are mixed evenly to obtain the additive for the PSA tin-insoluble anode system.

4. A method for preparing tin-plated plates using the additives for the PSA tin-insoluble anode system described in claim 3, characterized in that, The method includes: sequentially degreasing, electroplating, remelting, quenching, passivating and oiling a tin-plated substrate, wherein, during the quenching process, the additive for the PSA tin-insoluble anode system is added to the quenching tank, and the content of the additive is 0.6 to 1.0% based on the weight of the liquid in the quenching tank as 100%.

5. The method for preparing tin-plated plates using additives for PSA tin-insoluble anode systems according to claim 4, characterized in that, The content of this additive is 0.7% to 0.8% based on the weight of the liquid in the quenching tank as 100%.

6. The method for preparing tin-plated plates using additives for PSA tin-insoluble anode systems according to claim 4, characterized in that, The electroplating solution used in the electroplating process consists of: stannous sulfate 25-30 g / L, phenol sulfonic acid 15-20 g / L, α-naphthol polyoxyethylene ether 5-7 g / L, and α-naphthol sulfonic acid polyoxyethylene ether 2-4 g / L.

7. The method for preparing tin-plated plates using additives for PSA tin-insoluble anode systems according to claim 6, characterized in that, The electroplating solution used in the electroplating process consists of: stannous sulfate 26-28 g / L, phenol sulfonic acid 16-18 g / L, α-naphthol polyoxyethylene ether 5-5.5 g / L, and α-naphthol sulfonic acid polyoxyethylene ether 3-3.5 g / L.

8. The method for preparing tin-plated plates using additives for PSA tin-plating insoluble anode systems according to claim 6, characterized in that, The electroplating solution used in the electroplating process is at a temperature of 32–38℃, and the current density is 10–15 A / dm³. 2 .

9. The method for preparing tin-plated plates using additives for PSA tin-insoluble anode systems according to claim 4, characterized in that, During the passivation process, the passivation system consisted of a sodium dichromate concentration of 23–27 g / L, a pH value of 4.2–4.6, and a temperature of 41–43 °C.