阅读说明：本技术 一种薄钢板msa电镀锡工艺 (Thin steel plate MSA tin electroplating process ) 是由 梅华兴 黄勇军 梁爽 马辉 于 2021-08-02 设计创作，主要内容包括：本发明公开了一种薄钢板MSA电镀锡工艺,其中镀锡工艺是薄钢板依次进行焊接、碱洗、喷淋、烘干、拉矫、酸洗、喷淋、电镀锡、助熔、烘干、软熔、淬水、钝化、喷淋、烘干及涂油处理,处理后所得的薄钢板即为镀锡板。本发明所提供的一种薄钢板MSA电镀锡工艺采用一次性钝化,方便了生产操作,提高了MSA电镀锡生产线的作业效率,提升了涂膜附着力,使用本发明所提供的一种薄钢板MSA电镀锡工艺无需增加设备和改造设备,减少了额外生产费用,降低了生产成本；本发明适用于镀锡板材的钝化处理,用于MSA电镀锡生产线中的钝化步骤。(The invention discloses a thin steel plate MSA tin electroplating process, wherein the tin electroplating process comprises the steps of sequentially carrying out welding, alkali washing, spraying, drying, straightening and pulling, acid washing, spraying, tin electroplating, fluxing, drying, softening, quenching, passivating, spraying, drying and oil coating on a thin steel plate, and the thin steel plate obtained after treatment is a tin plate. The thin steel plate MSA tin electroplating process provided by the invention adopts one-time passivation, so that the production operation is convenient, the operation efficiency of an MSA tin electroplating production line is improved, the coating adhesion is improved, equipment does not need to be added and modified by using the thin steel plate MSA tin electroplating process provided by the invention, the additional production cost is reduced, and the production cost is reduced; the invention is suitable for passivation treatment of the tinned plate and is used for the passivation step in an MSA electrotinning production line.)

1. A thin steel plate MSA tin electroplating process is characterized in that: the tin plating process is characterized in that the thin steel plate is subjected to welding, alkali washing, spraying, drying, straightening and withdrawal, acid washing, spraying, electrotinning, fluxing, drying, reflow, quenching, passivating, spraying, drying and oil coating in sequence, and the processed thin steel plate is the tin plate.

2. The MSA tin electroplating process for a steel sheet as claimed in claim 1, wherein the process comprises the following steps: the electrolytic tinning is carried out by taking a thin steel plate as a cathode and soaking the thin steel plate in electroplating solution; the electroplating solution comprises methanesulfonic acid, an additive, sulfuric acid, an antioxidant and metallic tin.

3. The MSA tin electroplating process for a steel sheet as claimed in claim 2, wherein the steel sheet is prepared by the following steps: the concentration of the methanesulfonic acid is 35-60 mL/L; the additive is a surfactant, and the concentration of the additive is 14-45 mL/L; the metal tin is dissolved into a metal tin solution with the concentration of 15-25 g/L through a tin dissolving system; the antioxidant is one of hydroquinone, resorcinol, ascorbic acid, beta-naphthol, phenolsulfonic acid and vanadium pentoxide, and the concentration is not lower than 15 mL/L; the concentration of the sulfuric acid is 2-7 g/L.

4. The MSA tin electroplating process for a steel sheet as claimed in claim 1, wherein the process comprises the following steps: the passivation is cathodic electrolytic passivation; the cathode electrolytic passivation takes a thin steel plate as a cathode, and the thin steel plate and a passivation solution are subjected to oxidation-reduction reaction under the condition of electrifying; the redox reaction is carried out under the condition that the current density is 2.5-5.3C/ft²The reaction temperature is 30-50 ℃; the passivation solution is a sodium dichromate water solution with the concentration of 18-40 g/L.

5. The steel sheet MSA tin electroplating process as claimed in claim 4, wherein the steel sheet MSA tin electroplating process comprises the following steps: the pH value of the sodium dichromate solution is adjusted to 3.0-6.0 by chromic anhydride.

6. The steel sheet MSA tin electroplating process as claimed in claim 4, wherein the steel sheet MSA tin electroplating process comprises the following steps: the passivation solution is a sodium dichromate solution with the concentration of 20-35 g/L; the reaction temperature of the oxidation reduction is 35-45 ℃, and the current density is 2.8-5.0C/ft²。

7. The steel sheet MSA tin electroplating process as claimed in claim 6, wherein: the pH value of the sodium dichromate solution is adjusted to 3.5-5.5 by chromic anhydride.

8. The steel sheet MSA tin electroplating process as claimed in claim 6, wherein: the passivation solution is a sodium dichromate solution with the concentration of 24-31 g/L.

9. The MSA tin electroplating process for a steel sheet as claimed in claim 8, wherein the steel sheet is prepared by the following steps: the pH value of the sodium dichromate solution is adjusted to 4.0-5.0 by chromic anhydride.

10. The application of the MSA tin electroplating process for the thin steel plate as claimed in any one of claims 1 to 9, wherein the MSA tin electroplating process comprises the following steps: the MSA tin electroplating process for the thin steel plate is used for carrying out tin-plating passivation treatment on the thin steel plate with the thickness of 0.1-0.6 mm.

Technical Field

The invention belongs to the field of metal coating, and relates to a thin steel plate MSA (multi-site electroplating) tin electroplating process and application thereof.

Background

Tin-plated plate (commonly known as tinplate) is a steel plate plated with a thin layer of metallic tin on the surface. The tin plate is a finished product of a tin plate which is formed by rolling low-carbon steel into a steel plate with the thickness of 0.1-0.6 mm, carrying out acid cleaning, cold rolling, electrolytic cleaning annealing, leveling, edge shearing, cleaning, electroplating, reflowing, passivating, oiling and shearing. The tin plate has the advantages of no smell, no toxicity, light weight, easy processing and forming, etc. The printed patterns can beautify products, so the product is widely applied to the industries of food can industry, electronic devices, chemical paint and the like.

At present, the most widely applied and mature electroplating processes of the domestic tinned plate production line are PSA (phenolsulfonic acid) and MSA (methylsulfonic acid), wherein the MSA electroplating process belongs to an environment-friendly process, has little influence on the environment and is widely applied. In the production process of the tinplate, passivation treatment is a treatment step after an electroplating process, and the stability of the product in the processing and storage processes can be improved. The main purpose of passivation is to form a stable protective film on the surface, thereby improving the properties of oxidation resistance, corrosion resistance, sulfur resistance, paint film adhesion and the like.

The predominant passivation treatment currently used in the production of tinplate is chromate passivation, the most common of which is cathodic electrolytic passivation (311 passivation), which uses a sodium dichromate solution; in the passivation process, an anode is used to oxidize and reduce Cr in the passivation solution⁶⁺Reduction to Cr³⁺Or a layer of Cr forms a thin layer of chromium-containing oxide on the surface of the tinplate after passivation treatment. In addition, a 71 passivation process is characterized in that chromic anhydride is used as a main salt, concentrated sulfuric acid is used as an auxiliary agent to prepare a passivation solution, passivation is carried out according to a chromium plating process, and the adhesive force of a product coating film (namely a passivation film) is superior to that of a 311 passivation process product; the process uses high-concentration chromic anhydride solution and bath solution Cr⁶⁺The concentration is 4 times of that of the 311 passivation process bath solution, so that the highly toxic Cr substance remained on the surface of the tin plate⁶⁺Will increase proportionally; residual Cr⁶⁺May be partially introduced into food or drink, has high Cr residue⁶⁺It has carcinogenic risk to human body, and may also cause genetic defect of eaters. In addition, the 71 passivated products have unstable corrosion resistance and sulfur resistance, can only be used for low-tin products, and have narrow application range.

In various products applied to the tinplate, part of the products need to be steamed and boiled for a long time of 65 minutes at a high temperature of 127 ℃ after being canned, so that high quality requirements are provided for the coating adhesive force of a can body. In the conventional chromate process, under the normal 311 passivation condition, the product adhesion force is unstable, the problem that the tank body coating falls off during long-time high-temperature sterilization can be caused, and the use requirements of high-adhesion-force products such as high-temperature cooking products can not be met. Therefore, the tinplate passivation process needs to be developed to meet the use requirements of downstream customers on products.

Disclosure of Invention

In order to solve the defects in the prior art, the invention aims to provide a thin steel plate MSA tin electroplating process so as to achieve the purposes of improving the adhesive force of a tin coating on a tin plate, facilitating production operation, improving the operating efficiency of a production line, reducing the concentration of chromium ions in waste passivation solution and saving the cost of production and waste liquid treatment.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a thin steel plate MSA tin electroplating process is characterized in that the tin electroplating process is to sequentially perform welding, alkali washing, spraying, drying, straightening, acid washing, spraying, tin electroplating, fluxing, drying, soft melting, quenching, passivating, spraying, drying and oil coating on a thin steel plate, and the thin steel plate obtained after treatment is a tin-plated plate;

as a limitation of the invention, the electrolytic tinning is to perform electroplating treatment by taking a thin steel plate as a cathode and soaking the thin steel plate in an electroplating solution; the electroplating solution comprises methanesulfonic acid, an additive, sulfuric acid, an antioxidant and stannous fluoroborate;

the concentration of the methanesulfonic acid is 35-60 mL/L; the additive is a surfactant, and the concentration of the additive is 14-45 mL/L; the concentration of the stannous fluoborate is 15-25 g/L; the antioxidant is one of hydroquinone, resorcinol, ascorbic acid, beta-naphthol, phenolsulfonic acid and vanadium pentoxide, and the concentration is not lower than 15 mL/L; the concentration of the sulfuric acid is 2-7 g/L;

as another limitation of the invention, the passivation is cathodic electrolytic passivation; the cathode electrolytic passivation takes a thin steel plate as a cathode, and the thin steel plate and a passivation solution are subjected to oxidation-reduction reaction under the condition of electrifying;

the redox reaction is carried out under the condition that the current density is 2.5-5.3C/ft²The reaction temperature is 30-50 ℃; the passivation solution is a sodium dichromate water solution with the concentration of 18-40 g/L;

as a third limitation of the invention, the passivation solution is a sodium dichromate solution with a concentration of 20-35 g/L; the temperature of the passivation treatment is 35-45 ℃, and the current density is 2.8-5.0C/ft²；

As a further limitation of the present invention, the pH of the sodium dichromate solution is adjusted to 3.0 to 6.0 by chromic anhydride;

as a further limitation of the invention, the pH of the sodium dichromate solution is adjusted to 3.5-5.5 by chromic anhydride;

as a further limitation of the invention, the passivating solution is a sodium dichromate solution with the concentration of 24-31 g/L.

As a further limitation of the present invention, the pH of the sodium dichromate solution is adjusted to 4.0 to 5.0 by chromic anhydride;

the invention also provides application of the thin steel plate MSA tin electroplating process, and the thin steel plate MSA tin electroplating process is used for carrying out tin-plating passivation treatment on a thin steel plate with the thickness of 0.1-0.6 mm.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following beneficial effects:

(1) the thin steel plate MSA tin electroplating process provided by the invention adopts a one-step passivation process to replace a chromic acid two-step passivation mode, and does not need to switch or replace passivation solution in the passivation process, so that the production operation is convenient, the production line operation efficiency is improved, and the pollution of the passivation solution to the environment is reduced;

(2) the MSA tin electroplating process for the thin steel plate provided by the invention improves the coating adhesion, meets the coating adhesion performance requirement of a product with high adhesion requirement, and does not damage and influence the corrosion resistance, sulfur resistance, acid resistance and other performances of the product after tin plating;

(3) according to the thin steel plate MSA tin electroplating process provided by the invention, additional equipment is not required, and the equipment is not required to be modified, so that unnecessary production investment is reduced, and the production cost is reduced;

(4) the passivation solution in the thin steel plate MSA tin electroplating process can be supplemented according to the consumption of sodium dichromate in the production process, the passivation solution does not need to be replaced, chromium ions in the passivation solution can be completely consumed in the passivation engineering, the harmful influence of the waste passivation solution on the environment is reduced, and the cost of waste liquid treatment is reduced;

(5) the Chemical Oxygen Demand (COD) of the electroplating solution in the MSA tin electroplating process for the thin steel plate is 1/10-1/30 of the electroplating solution in the existing electroplating process, so that incomplete oxidation-reduction reaction of the waste electroplating solution can be prevented, the leakage of the electroplating solution caused by over-standard COD of the electroplating solution is avoided, and meanwhile, the electroplating solution used in the invention belongs to easily biodegradable organic matters, can be completely degraded within 24 days and meets the requirement of environmental protection;

(6) compared with the electroplating solution commonly used at present, the electroplating solution of the thin steel plate electroplating process provided by the invention can obtain a plating layer with better uniformity by using less tin;

(7) compared with the existing tin plating process, the MSA tin plating process for the thin steel plate can effectively save electricity by 8 percent, and reduces the production cost;

(8) the electroplating solution used in the thin steel plate MSA tin electroplating process provided by the invention only needs to adjust the pH value to 9 for sedimentation treatment in the post-treatment process, and no amorphous tin mud is generated, so that the post-treatment difficulty of the electroplating solution is reduced, and the workload of workers is reduced.

In conclusion, the thin steel plate MSA tin electroplating process provided by the invention adopts one-step passivation, so that the production operation is facilitated, the operation efficiency of an MSA tin electroplating production line is improved, the coating adhesion is improved, and the thin steel plate MSA tin electroplating process provided by the invention does not need to increase equipment and transform equipment, so that the additional production cost is reduced, and the production cost is reduced;

the invention is suitable for passivation treatment of the tinned plate and is used for the passivation step in an MSA electrotinning production line.

Drawings

The invention is described in further detail below with reference to the figures and the embodiments.

FIG. 1 is a flow chart of a process for MSA electrotinning a steel sheet according to example 1 of the present invention;

FIG. 2 is a schematic view of passivation process equipment in a thin steel sheet MSA tin electroplating process according to example 1 of the present invention;

FIG. 3 is a comparison chart of the adhesion detection results of the coating in the experimental example of the present invention.

In the figure: 1. tinning a metal plate; 2. passivating the conductive roller; 3. passivating the anode plate; 4. passivation tank

Detailed Description

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the description of the preferred embodiment is only for purposes of illustration and understanding, and is not intended to limit the invention.

Example 1 MSA tin electroplating Process for Steel sheet A1

The embodiment provides a MSA tin electroplating process A1 for a thin steel plate, the process flow chart is shown in FIG. 1, and the specific tin electroplating process comprises the following steps:

placing a thin steel plate coil with the thickness of 0.1-0.6 mm into an uncoiler for uncoiling, sequentially passing the thin steel plate through an alkali washing section, a spraying section, a drying section, a withdrawal straightening machine, an acid washing section, a spraying section, an electrolytic tinning section, a fluxing section, a drying section, a softening section, a quenching section, a passivating section, a drying section and an oil coating section by using a rolling transmission device, cutting and uncoiling the strip steel by using a flying shear, and coiling by using a coiling machine to obtain a tinned plate coil, wherein the moving track of the thin steel plate is shown in figure 1;

wherein the steel sheet 1 as a cathode is transported by a rolling transportation means into a plating solution containing a metallic tin solution dissolved in a tin dissolution system at a concentration of 18g/L as an insoluble anode and containing methanesulfonic acid at a concentration of 41mL/L, a surfactant STANTEK TP XD 7744ADDITIVE at a concentration of 16mL/L, hydroquinone at a concentration of 25mL/L and sulfuric acid at a concentration of 2g/L, and the steel sheet 1 is dipped for an average of 20 seconds per stage under energization to perform a plating treatment;

when entering the passivation stage (as shown in figure 2), the steel sheet 1 is rolled and clamped by a rolling transportation device and a passivation conductive roller 2 and continuously passes through a passivation tank 4 filled with passivation solution with the concentration of 27g/L and the pH value of 4.5 and a passivation anode plate 3, and the current density reaches 4.5C/ft by electrifying the steel sheet 1 through the passivation tank 4²And raising the temperature of the passivation solution to 40 ℃, enabling the steel sheet 1 as the cathode to averagely stay in the passivation solution for 1s, and carrying out oxidation-reduction reaction to generate a layer of passivation film on the surface of the steel sheet, namely finishing the passivation of the steel sheet.

Examples 2 to 7 MSA tin plating process for thin steel sheets A2 to A7

The steel sheet MSA tin electroplating processes A2-A7 provided in the embodiments 2-7 respectively have the same specific steps as those of the embodiment 1, and only differ in part of the process parameters, and the specific process parameters are shown in Table 1.

Table 1: thin steel plate MSA tin electroplating process

The other process parameters were the same as in example 1.

Experimental example 1 Effect on coating film adhesion at high temperature

A 71 passivation process and a conventional 311 passivation process were used as comparative examples 1 and 2, respectively.

In the experimental example, the passivated tin plate in the comparative example 1, the comparative example 2 and any one of the above examples is placed in a high-temperature environment for coating adhesion detection (the coating adhesion is detected by a cross-cut method, the detection standard is shown in table 2), and the detection conditions and the detection results are shown in table 3.

Table 2: coating film adhesion detection standard

Table 3: special detection condition and result for coating adhesion

The actual figure is shown in FIG. 3, wherein the actual figure of comparative example 1 is shown in figures a 1-a 3 respectively corresponding to conditions 1-3; the material object diagram of the invention is shown in the figures b 1-b 3 respectively corresponding to the conditions 1-3; the actual figures of comparative example 2 are c1 to c3 corresponding to conditions 1 to 3, respectively, where DLO represents the maximum length of peeling of the coating film.

As can be seen from table 2, table 3 and fig. 3, the 71 passivation process has the best coating adhesion, but the required passivation solution is not listed in the current tinplate product standard; meanwhile, the residual of 6-valent chromium ions can be increased by using the 71-passivated tin plate surface, so that the food safety risk can be increased; the conventional 311 passivation process has poor film adhesion, and the film falls off in a large area under the condition 3.

Experimental example 2 Corrosion resistance test

(ii) iron dissolution test

The metal plate with tin-plated passivation, which is prepared by the MSA tin electroplating process for the steel sheet selected from the comparative example 1, the comparative example 2 and any one of the examples 1 to 7, is treated by placing the sample in a 0.5% Na2CO3 solution, removing oil from the cathode at a current of 1.5A, removing oil from the stainless steel anode for about 30 seconds, washing with distilled water, wiping the surface of the sample with absorbent cotton dipped with acetone, and drying with cold air. A sample plate was cut out in accordance with GB/T2520-Cold-rolled tin-electroplated Steel sheet ], and a corrosion resistance test was carried out in accordance with GB/T22316 corrosion resistance test method (iron dissolution value test method), and the test results were subjected to colorimetric analysis as shown in Table 4.

Table 4: table of iron dissolution test results

As shown in table 4, the tinplate passivated by the passivation process according to the present invention has similar colorimetric results to those of comparative examples 1 and 2, i.e., the passivation process according to the present invention has almost no effect on the tin plating of the metal plate.

(ii) Corrosion resistance test

Re-selecting the same sample plates as the first step, carrying out corrosion resistance detection according to a neutral salt spray test (NSS test) related in GB/T10125-salt spray test for artificial atmosphere corrosion test, respectively weighing the mass of each sample plate before the test is started, weighing the mass of each sample plate again after the detection is finished, and calculating the mass loss rate eta of each sample plate, wherein the calculation formula is as follows: eta is 100% (M)_{First stage}-M_Powder)/M_{First stage}The test results are shown in Table 5.

Table 5: corrosion resistance test results table

Item	Initial mass MFirst stage(g)	Mass M after testPowder(g)	Loss rate eta (%)
				Comparative example 1	10.56	10.23	3.14
The invention	11.06	10.92	1.23
				Comparative example 2	10.81	10.30	4.69

As can be seen from table 5, compared with the test results of comparative examples 1 and 2, the quality loss of the sample plate of the metal plate treated by the passivation process of the present invention is the lowest, i.e. the passivation process of the present invention can make the tin-plated metal plate have more excellent corrosion resistance.

In conclusion, the steel sheet MSA tin electroplating process provided by the invention can effectively improve the coating adhesion of the tin-plated sheet, and has no toxicity and harm, and has no influence on other properties of the tin-plated sheet.

Although the present invention has been described in detail with reference to the above embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the above embodiments, or equivalents may be substituted for some of the features thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.