KR100685026B1 - Chrome free post treatment solution and method for manufacturing electrolytic tinplate steel sheet using it - Google Patents

Abstract

Provided is a post-treatment solution that does not contain chromium and a method for producing an electro-tin plated steel sheet using the same.

The present invention is a chromium composition comprising tin: 1-3 g / L and phytic acid (C ₆ H ₁₈ O ₂₄ P ₆ ): 0.1-0.5 g / L with respect to 8 g / L phosphoric acid composition The post-treatment solution containing no tin-plated electroplated steel,

After the tin-plated cold-rolled steel sheet is reflowed, and then, in the manufacturing process of the tin-plated steel sheet which is post-processed, the flow-treated tin plated steel sheet is post-processed using the above-described post-treatment solution. The present invention relates to a method for producing a chrome-free electro tin plated steel sheet having excellent surface gloss and oxidation resistance.

The present invention is useful for producing a tin-plated steel sheet for white pipe having excellent surface gloss and oxidation resistance.

Tin Plating, Reflow, Surface Gloss, Oxidation Resistance

Description

Chrome free post treatment solution and method for manufacturing electrolytic tinplate steel sheet using it}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a method of post-treatment after an electroplating and reflow process without adjusting the amount of tin deposition in an electro tin plated steel sheet manufacturing process (Ferrostan Process) of an acid plating bath containing an additive. . More specifically, instead of using a conventional chromium solution, an environmentally friendly post-treatment solution without chromium is used, and by using this method, a method of manufacturing a tin plated steel sheet having excellent surface appearance and excellent quality characteristics such as oxidation resistance is used. It is about.

In general, the solution used for chromate treatment in the tin-plated steel sheet manufacturing process is mainly composed of hexavalent chromium, but hexavalent chromium is reduced to trivalent chromium by electrolytic reaction. Therefore, even if the chemically treated film is eluted in the contents, the human body ingesting it does not harm hexavalent chromium, but from the point of view of the actual consumer, it is suspected that it is a harmful substance and the tendency to avoid such substances is increasing. In addition, since the hexavalent chromic anhydride must be handled in terms of its manufacturing process, it is required to be cautious from the viewpoint of the factory employee. Therefore, it is desirable to do post-treatment with materials that the manufacturing process stakeholders and end-users can be more confident in, which means eliminating the use of hexavalent chromium in the working environment.

Tin oxide produced after tin plating and reflow treatment has a rust preventing ability, but has a disadvantage of discoloration, that is, yellowing. Therefore, chromate post-treatment methods used to date are mainly cathodic electrolytic methods to prevent discoloration in the wet atmosphere and the baking process during the lacquer process to secure the surface appearance and improve lacquer adhesion.

Tin-coated steel sheet used in beverage cans and food cans is roughly classified into white pipe and lacquer treatments without lacquer treatment. In some cases, such as fruit cans and powdered milk cans, they are used without lacquer coating on the inside, which is called a plain can. In the case of fruit cans, a part of tin on the inner surface side of the can is oxidized and dissolved by fruit and acid in the syrup and oxygen in the head space to prevent oxidation of the contents, while maintaining the strength of the contents and preventing discoloration. In addition, when the powdered milk can is lacquered, the surface appearance of the powdered milk can be deteriorated and the cost is increased. By the way, chromate treatment is also performed for white tube use, in order to suppress tin oxide growth and prevent discoloration of the surface appearance to yellowing at an early stage. The lacquered coating prevents corrosion of the steel sheet depending on the contents and prevents the taste and appearance of the contents from being changed by the eluted metal.

In conventional chromated steel sheets, the chromium (III) oxide layer is oxidized on the tin surface to grow into tin oxide (II) (SnO) and tin oxide (IV) (SnO ₂ ) layers. Therefore, it is easy to agglomerate and break, which causes a poor adhesion between the coating film and the laminated resin. In addition, excessive oxide film thickness causes flaking during lacquer treatment, yellowish appearance and is transferred as it is after lacquer treatment. Therefore, there is a need to replace the chromium trivalent hydroxide layer, which is fragile as an environmental control material, to provide an excellent surface appearance and oxidation resistance, and to supply an environmentally friendly material without chromium in the plating layer as a post-treatment solution.

In order to solve the above problem, studies on the post-treatment method without chromium are actively conducted. For example, Japanese Laid-Open Patent Publication No. 2002-206191 discloses post-treatment using a P-Si-based silane coupling agent after reflow treatment in a steel strip with a nickel-plated thin tin plating amount (0.05-2.0 g / m ² ). It is proposed to improve paint adhesion and rust resistance. However, this method has a low manufacturing cost due to tin foil plating, but the manufacturing process is complicated and the overall cost increases due to nickel pretreatment and immersion treatment of epoxy-based silane (Silane).

As another prior art sikindago increase the oxidation resistance by forming a coating film of poly-phosphate (2-40mg / ² m) containing magnesium ions (0.1-10 mg / m ²⁾ in the tin-plated surface in the Japanese Patent No. 2002-60958 porous Suggesting. In addition, Japanese Laid-Open Patent Publication No. 2003-82497 discloses a treatment method for preventing pinhole formation by the iron phosphate composition in the lower layer and a phosphate-based film containing magnesium ions in the upper layer, thereby making the surface appearance, corrosion resistance, oxidation resistance, and organic film adhesion It suggests that it can be secured. Specifically, the production methods disclosed in the two publications use a solution pH 2.0-3.5 range, and in Japanese Patent Application Laid-Open No. 2002-60958, the coating or dipping is heated to 95-200 ° C., while Japanese Patent Application No. 2003-82497 After electrolysis, they choose either a positive electrode electrolytic method or an electrolytic solution after electrolysis to heat or dry at 70-200 ℃. However, the method requires heat treatment at a temperature of 75-200 ° C., thus adding a process and increasing manufacturing costs.

Separately, as a phosphate-based chemical treatment method, Japanese Patent Application Laid-Open No. 49-28539 said that the treatment of the cathode layer or the immersion method in the composition containing calcium phosphate and magnesium phosphate had a flaw preventing effect of the base layer. It does not have a great effect on improving corrosion resistance. In addition, Japanese Patent Application Laid-Open No. 52-75626 says that the composition containing calcium phosphate and magnesium phosphate contributes to the improvement of corrosion resistance by the anode electrolytic treatment after the cathode electrolysis, but there is a limitation in that an electrolytic facility must be added in the manufacturing process. .

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, a tin-plated steel sheet excellent in oxidation resistance for suppressing the occurrence of gloss and smuggling, which is the surface appearance of the electro-tin-plated steel sheet applied to the post-treatment process. It is an object of the present invention to provide a post-treatment solution that does not contain chromium.

In addition, an object of the present invention is to provide a method for producing an electro tin plated steel sheet having excellent surface gloss and oxidation resistance using the post-treatment solution.

Hereinafter, the present invention will be described.

As described above, the tin-plated steel sheet for white pipe, which does not require lacquer treatment, should have excellent smudge characteristics related to glossiness and oxidative properties, which are surface appearance items. These characteristics, which are subjective criteria of demand, can be used as indicators to quantify the quality characteristics of tin plated steel products. Among these indices, the surface glossiness is related to the total amount of reflection of light, and the smudge characteristics are indices respectively related to the oxidation characteristics of the film.

Therefore, the present inventors repeated experiments and studies to overcome the limitations of the prior art, and as a result, a post-treatment solution capable of producing a chromium-free tin plated steel sheet having excellent surface appearance and good oxidation resistance and using the same The manufacturing method of electro tin plated steel sheet was developed.

Therefore, the present invention, for the composition of phosphate 8 g / L, comprising tin: 1-3 g / L and phytic acid (C ₆ H ₁₈ O ₂₄ P ₆ ): 0.1-0.5 g / L The present invention relates to a post-treatment solution of an electroplated steel sheet containing no chromium.

In addition, the present invention, in the manufacturing process of the tin-plated steel sheet after the tin-plated cold-rolled steel sheet, and then post-treatment, the reflowed tin-plated steel sheet, the pH of the solution is 2.0-3.0 And a surface gloss and oxidation resistance of the chromium-free electro tin plated steel sheet, which is immersed in the above-mentioned aftertreatment solution maintained at a temperature range of 50-60 ° C.

In addition, the present invention, in the manufacturing process of the tin-plated steel sheet after the tin-plated cold rolled steel sheet, and then post-treatment, on the surface of the reflowed tin-plated steel sheet, the pH of the solution is 2.0- The present invention relates to a method for producing a chromium-free electro tin plated steel sheet having a surface gloss and oxidation resistance of 3.0 and spraying the aftertreatment solution maintained at a temperature range of 50-60 ° C.

Hereinafter, the post-treatment solution of the present invention will be described.

The post-treatment solution of the present invention is characterized in that it contains the amount of tin and organic additives in the tin phosphate solution to improve the surface appearance of the electroplated steel sheet.

Specifically, the post-treatment solution of the present invention preferably contains tin in the amount of 1-3 g / L based on the amount of phosphoric acid 8 g / L.

If the amount of tin added is less than 1 g / L in the post-treatment solution composition, the stability of the solution may be poor and the amount of phosphoric acid adhesion may be reduced, resulting in deterioration of oxidation resistance and surface appearance. As the cost increases, the effect can be offset.

In addition, the post-treatment solution of the present invention preferably contains phytic acid (Phytic acid, C ₆ H ₁₈ O ₂₄ P ₆ ) in the range of 0.1-0.5 g / L relative to the amount of phosphoric acid 8 g / L. Such phytic acid is widely used in food and industrial use among organic additives, and serves to prevent corrosion or dissolution and dissolution of material metal through internal treatment of food and beverage cans. However, if the added amount is less than 0.1 g / L, the amount of phosphoric acid deposition is small, and if it exceeds 0.5 g / L, the amount of phosphoric acid deposition may be excessively increased.

In addition, the post-treatment solution of the present invention may contain a sodium pyrophosphate solution, a sodium chlorate solution, and a sodium carbonate solution. However, the present invention is not limited to the kind and the individual content of these residual components.

Next, an electro tin plated steel sheet manufacturing process of the present invention using the post-treatment solution will be described.

The present invention can be applied to the manufacturing process of the electro-tin-plated steel sheet after reflow treatment after tin-plated cold-rolled steel sheet, and then post-treating it.

That is, in the present invention, chromium-free tin-plated steel sheet can be manufactured by subjecting the material heated in the reflow step after tin plating to the post-treatment step using the phosphate solution as described above. Technology developed.

As such post-treatment methods, there are various treatment methods such as immersion, cathodic electrolysis, and cathodic electrolysis, but it is advantageous to select the most excellent method in terms of equipment interference, manufacturing cost, and ease of manufacture. In addition, the immersion method may be a simple immersion method and a spray method, and the immersion method and the spray method can be processed in parallel. In addition, the electrolytic method can be prepared in the same manner as the existing electrolytic chromate treatment method, it can be performed in combination with the positive electrode treatment after the negative electrode treatment.

However, the present invention was developed for the purpose of use as a milk pipe for milk powder, lacca adhesion and corrosion resistance is not very important, the surface appearance of the gloss and oxidation resistance for suppressing the generation of smudges becomes important. From this point of view, cathodic electrolytic treatment is preferable in terms of the ability to adjust the film deposition amount uniformly and uniformly, but it is not preferable because the oxidation resistance is deteriorated due to the increase in the thickness of the oxide film. It is undesirable because additional installation of the equipment must be followed.

Therefore, the present invention is characterized in that it provides a chromium-free tin plated steel sheet through the immersion method so that it is quick, simple, and advantageous in terms of manufacturing cost and imparts surface appearance and oxidation resistance without retrofitting an existing post-treatment facility.

As described above, these immersion methods include a simple immersion method and a spray method, and both of them can be adopted in the present invention. That is, chromium-free tin having excellent surface gloss and oxidation resistance by immersing the reflowed tin plated steel sheet in the post-treatment solution of the present invention or spraying the post-treatment solution of the present invention on the reflow-treated tin plated steel sheet. A plated steel sheet can be provided.

However, in the present invention, it is preferable at this time to control the pH of the post-treatment solution to 2.0-3.0. If the pH of the solution is less than 2.0, the gloss deteriorates due to the etching on the surface, and if the pH exceeds 3.0, the effect of improving the performance of the plating layer, such as oxidation resistance and corrosion resistance, may be insufficient.

In the present invention, it is preferable to limit the temperature of the after-treatment solution to 50-60 ℃ range. If the temperature of the post-treatment solution exceeds 60 ° C, the amount of phosphoric acid deposition and the amount of oxide film are increased at the same time, which is undesirable.

The tin-plated steel sheet of the present invention manufactured by using the aftertreatment solution and the aftertreatment process as described above has excellent surface gloss and oxidation resistance. Furthermore, in the preceding tin plating process, the final manufactured tin plated steel sheet can secure excellent surface appearance and oxidation resistance without changing ordinary additives or tin plating solution temperature, concentration, and reflow conditions.

Hereinafter, the present invention will be described in detail through a preferred embodiment.

(Example)

A cold carbon steel sheet of 0.25 mm thickness, which is a raw material, was subjected to electrolytic degreasing after electrolytic degreasing as a pretreatment. Then, after plating of 5.6 g / m ² using a phenolsulfonic acid plating solution system, a reflow treatment was performed. The reflow-treated steel sheet was immersed in a post-treatment solution prepared as shown in Table 1 by varying the conditions thereof to perform post-treatment. Meanwhile, for comparison, one specimen was subjected to post-treatment using a cathodic electrolytic treatment.

The post-treated specimens were evaluated for phosphoric acid adhesion, glossiness, oxidation resistance, oxide film thickness, corrosion resistance, and the like, and the results are shown in Table 1 below. In this case, the phosphate coating weight was measured by inductively coupled plasma spectrometry (ICP), gloss was measured 60 ^o specular glossiness (Gs60 ^o) perpendicular to the rolling direction. If Gs60 ^o is 700 or more, the present invention exhibits a high gloss level without spots on the surface.

On the other hand, oxidation resistance was performed by dividing tin oxide film thickness and smudge resistance evaluation. The oxide film thickness was expressed as the amount of electric charge required for reduction by the constant current method, and the oxide film amount of the electrolytic chromate treated specimen was 4 mC / cm. ^In consideration of being ² it was 4 mC / cm ² or less as the scope of the present invention. The smudge property was evaluated by measuring the degree of whiteness transferred to the filter paper after reciprocating twice with a magnetite press having a constant force on a specimen heat-treated at 215 ° C. for 15 minutes. The above was made into this invention range.

Composition (g / L) Treatment condition Amount of Attachment (mg / m ² ) Oxidation resistance Glossiness (Gs60 °) Phosphoric Acid Remark Phytic acid Temperature (℃) pH Oxidation film amount (mC / cm ² ) Smudge (Whiteness) Foot honor One 8 1.0 0.3 50 2.5 2.5 3.11 87.5 754 2 2.4 0.5 55 3.0 3.1 3.12 87.1 768 3 2.7 0.2 54 2.9 2.6 2.87 87.4 764 4 2.7 0.3 60 2.4 3.5 3.12 85.5 819 5 3.0 0.4 53 2.6 2.7 4.08 87.2 763 6 2.5 0.1 53 2.5 4.4 2.65 86.0 750 7 1.9 0.4 58 2.3 2.9 2.89 89.1 759 8 2.0 0.2 54 2.9 4.7 2.65 87.3 760 9 2.5 0.3 55 2.6 2.5 2.56 87.9 765 Comparative Example One 8 0.6 0.1 55 3.5 1.2 5.74 75.1 659 2 0.5 1.0 45 2.5 1.1 5.86 79.8 640 3 3.5 1.5 53 1.8 4.0 3.98 80.8 634 4 4.0 1.5 65 2.0 4.5 6.18 83.4 690 5 2.0 0.5 60 3.5 2.3 5.87 81.5 641 6 2.5 1.0 48 2.8 3.5 4.85 78.9 715 7 5.0 0.5 50 2.5 4.4 3.73 82.5 680 8 4.0 1.5 63 2.9 3.8 4.23 80.1 695 9 3.0 1.0 37 3.3 3.9 4.51 81.8 724 10 2.0 0.3 53 3.0 3.2 5.90 80.5 731

As shown in Table 1, in the case of Inventive Example (1-9) subjected to the post-treatment under the conditions of the present invention using the post-treatment solution of the present invention, all of the tin-plated steel sheet excellent in surface gloss and oxidation resistance It can be seen that.

On the contrary, Comparative Example (1-2) having a low tin content was deteriorated in oxidation resistance due to a small amount of phosphoric acid deposition, and Comparative Examples (3, 4, 7, 8) and the like have a large amount of oxide film, resulting in deterioration of surface glossiness.

In addition, Comparative Example 10 shows the specimen by the cathode electrolytic treatment method, it can be seen that the smudge characteristics worse with increasing the thickness of the oxide film.

Meanwhile, the present invention has been described through the above-described embodiments, but the present invention is not limited to the description of these embodiments. For example, the above-described embodiment described a post-treatment method using an immersion method, but it is common knowledge in the art that the desired effect in the present invention can be achieved by the spray method using the same post-treatment solution. It is too obvious to those who have.

As described above, the present invention is useful in producing an electro-tin plated steel sheet which can secure an appropriate coating amount by optimizing a post-treatment solution component and its post-treatment conditions, and has excellent oxidation resistance and extremely excellent surface appearance.

Claims (3)

For composition of 8 g / L phosphoric acid, tin: 1-3 g / L and phytic acid (C ₆ H ₁₈ O ₂₄ P ₆ ): 0.1-0.5 g / L free of chromium Post-treatment solution for electroplated steel sheets. In the manufacturing process of the tin-plated steel sheet after tin-plating the cold rolled steel sheet, and then post-treatment, the reflowed tin-plated steel sheet, the pH of the solution is 2.0-3.0 and 50-60 ℃ Method for producing a surface of the chromium-free electro-tin plated steel, characterized in that it is immersed in the after-treatment solution of claim 1 maintaining the temperature range of. In the manufacturing process of the tin-plated steel sheet after tin-plating the cold rolled steel sheet, and then post-treatment, on the surface of the reflowed tin-plated steel sheet, the pH of the solution is 2.0-3.0 and 50-60 A method of producing a chrome-free electro tin plated steel sheet with surface gloss and oxidation resistance, characterized by spraying the aftertreatment solution according to claim 1 maintaining a temperature range of ℃.