KR20040034218A - Densed chromate solution and its replenished solution for the purpose of postreatment on zinc galvanized sheet - Google Patents

Abstract

PURPOSE: A dense chromate solution for posttreatment of galvanized strip is provided which contributes to uniformization of coating weight by stabilizing concentration of the dense chromate solution and produces high quality product, and a supplement solution of the dense chromate solution is provided. CONSTITUTION: The initial dense chromate solution for post-chrome treating electrogalvanized strip comprises 1.5 to 2.6 vol.% of CrO3, 1.5 to 3.0 vol.% of MP3, 7.5 to 10.5 vol.% of AJ4763, 2.6 to 4.6 vol.% of H2SO4 and a balance of pure water. The supplement solution for post-chrome treating electrogalvanized strip comprises 3.6 to 4.0 vol.% of CrO3, 0.6 to 1.2 vol.% of MP3, 18.2 to 20.2 vol.% of AJ4763, 6.6 to 8.6 vol.% of H2SO4 and a balance of pure water.

Description

Densed chromate solution and its replenished solution for the purpose of postreatment on zinc galvanized sheet}

The present invention relates to a hookrom solution and its refill material solution used in the hookrom treatment operation, which is an electroplating post-treatment process, and more specifically, to stabilize the hookrom concentration, and to promote uniformity of adhesion. The present invention relates to a chrome solution for post-treatment of a galvanized steel sheet capable of producing a beautiful hook-rom color and a replenishment solution thereof.

In general, electroplated galvanized steel products have been requested to develop hookrom solutions that can improve the rust prevention performance in order to prevent discoloration of hookromed parts on the surface of galvanized coatings when stored for a long time in areas with high corrosion resistance and moisture. have.

Therefore, the inventor of the present application has been filed in the Republic of Korea Patent Application (Application No. 1994-13535) for a method and apparatus for producing a hookrom solution that can improve the above point.

The patent application after the chrome free acid adjustment solution (AJ 4763 _{component) (NO₃29.2% H 2 O 70.8} %), sulfuric acid ions adjustment solution (AJ 4775 ^{_{component) (SO 4 2- 20% H}} 2 O 80%), Chromic acid concentration control solution (ZM 357 SRP component) (Cr 10.2% NH₄ + 1.9% F-4.1% Cl- 4.8% H₂o 79%) Dilute and mix pure water with 1 part solution or Hook-Rom solution 1 part mixing ratio AJ4763 A technique for hook-roming a surface layer of an electro-zinc plated steel sheet using a hookrom solution made of components (29%), AJ 4775 component (0.84%), ZM357SRP component (3.9%), and pure water (66%) is presented. .

In addition, the patent application proposes a technique for post-treatment of an electro-galvanized steel sheet using a hook-rom solution supply device as shown in FIG. Specifically, in the patent application, as shown in Fig. 1, a pure water supply pipe 4 and a lid 8 having a pure water supply control valve 7 formed thereon are formed, and the level gauge 5 and the stirrer in the front and rear sides. The supply tank (5) through the mixing tank (1), each of which (6) is provided, and the supply tank (5) and the supply liquid supply pipe (11) which communicate with the mixing tank (1) through the mixed liquid supply pipe (9). The hook tank solution supply device including a circulation tank (3) in communication with, and a plating portion 15 in communication with the circulation tank (3) through the circulation liquid supply pipe (14) is proposed.

However, even in the above-described method, there is a problem of discoloration or deterioration in corrosion resistance of hookromed portions of the galvanized surface layer when the hookromed products are stored in a humid place for a long time, and also due to uneven chromium deposition. The color of haze remained uneven and of course uneven and contributed to improving the production of hookrom products.

Therefore, the present invention is to solve the above problems of the prior art, it is possible to promote the uniformity of the adhesion amount by stabilizing the hookrom concentration, and also to form a beautiful hookrome color galvanized steel sheet that can produce a good product It is an object of the present invention to provide a chromium solution for post-treatment and a solution of a filler thereof.

1 is a block diagram of a hookrom solution supply device used in the present invention.

* Description of the symbols for the main parts of the drawings *

1: mixing tank 2: supply tank

3: circulation tank 4: pure water supply pipe

5: level gauge 6: stirrer

7: Pure water supply control valve 8: Lid

9: Mixed solution supply line 10: Mixed solution control valve

11: Supply liquid supply line 12: Metering pump

13: discharge line 14: circulating fluid supply line

15: plating part

The present invention for achieving the above object is, in Vol.%, CrO ₃ : 1.5-2.6%, MP3: 1.5-3.0%, AJ4763: 7.5-10.5%, H ₂ SO ₄ : 2.6-4.6%, the residual pure water The present invention relates to an initial hookrom solution for chrome post-treatment of an electrogalvanized steel sheet.

In addition, the present invention, in the Vol.%, CrO ₃ : 3.6 ~ 4.0%, MP3: 0.6 ~ 1.2%, AJ4763: 18.2 ~ 20.2%, H ₂ SO ₄ : 6.6 ~ 8.6%, galvanized steel sheet consisting of the balance pure water The present invention relates to a chromium post-treatment feedstock solution.

Hereinafter, the hookrom solution of the present invention and a refill material solution thereof will be described.

First, the hookrom solution of the present invention is for initially hookromating the surface of an electrogalvanized steel sheet, and this solution is a first solution (a solution containing CrO ₃ component) and a second solution [MP3 component (methyl, pinazolin) the aqueous solution containing - a third solution [AJ4763 component (NHO ₃₎ containing an aqueous solution], and the second is prepared by appropriately mixing a solution of 4 (H ₂ SO ₄ aqueous solution containing component).

In the hookrom solution of the present invention, first, the content of CrO ₃ constituting the first solution is limited to 1.5% to 2.6% by volume based on the total volume of the chromium solution unit (1m ³ ). If the CrO ₃ content is less than 1.5%, the CrO ₃ concentration and the chromium deposition amount are less than the target, while if the CrO ₃ content is more than 2.6%, the CrO ₃ concentration and the chromium deposition amount may be larger than the target.

In addition, the content of MP3 constituting the second solution is limited to 1.5 ~ 3.0%. This is because if the content is less than 1.5%, discoloration may occur at the edge portion of the hook-romed galvanized steel sheet, and if it exceeds 3.0%, suspended matter (sludge) may occur in the hookrom solution.

In the hookrom solution of the present invention, the AJ4763 content constituting the third solution is limited to 7.5 to 10.5%. If the content is less than 7.5%, the free acid concentration and the amount of chromium adhesion may be lower than the target. If the content exceeds 10.5%, the free acid concentration is higher than the target and the existing plating layer is nicknamed, so the amount of chromium is higher than the target.

The hookrom solution of the present invention is further composed of H ₂ SO ₄ and the balance pure water constituting the fourth solution. At this time, the H ₂ SO ₄ content constituting the fourth solution is required to be limited to 2.6 ~ 4.6%, because if the content is too small, the color of the hook-romed surface becomes cloudy and the yellowness is dark when excessive.

The hookrom solution of the present invention prepared as described above has a color of bluish brown to black, a pH of 1 or less, and a specific gravity of about 1.100 to 1.200.

Next, the filler solution of the present invention will be described. The replenisher solution is a solution that discharges a certain amount and replenishes with fresh fresh solution to prevent aging of the hookrom solution as the hookrom treatment is performed on the galvanized steel sheet. Such a replenisher solution is basically the same hookrom solution and its composition, but the composition range is different from each other.

The replenisher solution of the present invention may be prepared by mixing the above-described first to fourth solutions in an appropriate mixing ratio so as to satisfy the following component ranges.

First, the replenishment solution of the present invention is composed by containing 3.6 to 4.0% by volume of CrO ₃ constituting the first solution, based on the volume of the total replenishment solution volume (1 m ³ ). If the CrO ₃ content is less than 3.6%, the CrO ₃ concentration and the chromium deposition amount are less than the target, while if the CrO ₃ content is higher than 4.0%, the CrO ₃ concentration and the chromium deposition amount may be higher than the target.

In addition, MP3 constituting the second solution is included in the range of 0.6 ~ 1.2%. If the MP3 content is less than 0.6%, discoloration may occur at the edges of the hook-coated galvanized steel sheet, and if it exceeds 1.2%, suspended matter (sludge) may occur in the hookrom solution.

And the replenishment solution of the present invention comprises AJ4763 constituting the third solution in the range of 18.2 ~ 20.2%. If the content is less than 18.2%, the free acid concentration and the amount of chromium deposition may be lower than the target. If the content exceeds 10.5%, the free acid concentration is higher than the target.

In addition, the composition is in a fourth solution of H ₂ SO ₄ and the balance constituting the pure. At this time, the H ₂ SO ₄ content constituting the fourth solution is required to be limited to 6.6-8.6%, because if the content is too small, the color of the hook-romed surface becomes cloudy and the yellowness is dark when excessive.

Hereinafter, with reference to the accompanying drawings will be described a process of hook-roming the surface of the electro-galvanized steel sheet using a solution provided as described above.

1 is a schematic view showing a hookrom solution supply apparatus used in the present invention.

That is, as shown in Figure 1, the pure water supply pipe (4) for supplying pure water to the upper surface of the mixing tank (1) having a predetermined closed space is connected, the mixing so that the operator can visually check the supply amount of pure water On the outer surface of the tank 1, a level gauge 5 made of a transparent member is formed. And the other side of the mixing tank (1) is provided with a stirrer (6).

In addition, the hookrom solution mixed in the mixing tank (1) is supplied to the supply tank (2) through the mixed liquid supply pipe (9), the mixed liquid supply pipe (9) to the mixed liquid control valve to adjust the supply amount of the mixed solution ( 10) is installed.

And the solution stored in the supply tank (2) is supplied to the circulation tank (3) through the feed liquid supply pipe (11), the feed liquid supply pipe (11) metering pump to transfer the correct amount of the solution to the circulation tank (12) is provided. In addition, the circulating fluid supply pipe 14 is installed to circulate the solution in the circulation tank 3 to the plating unit 15.

First, for example, 1 solution (CrO ₃ component: 3.8%, H ₂ O: 96.2%), 2 solution (MP3: 4.3%, H ₂ O: 95.7%), 3 solution (AJ4763 (NHO) in the circulation tank (3) ₃ ): 4.8%, H ₂ O: 95.2%) and 4 solutions (H ₂ SO ₄ : 6.4%, H ₂ O: 93.6%) by mixing with pure water, CrO ₃ : 2.11Vol.%, MP3: 2.22 Vol.%, AJ4763 (NHO ₃ ): 9Vol.%, H ₂ SO ₄ : 3.61Vol.%, The initial composition can be prepared a predetermined composition consisting of residual pure water, the color of the chromium solution is blue brown ~ It is black and has a pH of 1 or less and a specific gravity of 1.100 to 1.200.

The initial chromium solution prepared as described above is circulated and supplied to the plating unit 15 through the circulating fluid supply pipe 14 to perform a Cr post-treatment on the surface of the galvanized steel sheet passing through the plating unit 15.

On the other hand, such an initial chromium solution, as the chrome post-treatment process for the galvanized steel sheet continues, the chromium solution is depleted or its components are changed. Therefore, it is necessary to supply a replenishment solution to adequately replenish the initial chromium solution.

The replenishment solution of the present invention may be prepared by appropriately mixing the first to fourth solutions with pure water in the mixing tank (1). That is, while operating the pure water supply control valve (7) to supply a predetermined amount of pure water to the mixing tank (1), the cap 8 is opened and the first to fourth solutions described above by a predetermined amount, the stirrer By operating (6), the raw material solution and the pure water can be uniformly mixed to prepare a replenishment solution having a standard concentration. For example, in the mixing tank 1, the first solution (CrO ₃ component: 2.0%, H ₂ O: 98%), the second solution (MP3: 2.0%, H ₂ O: 98%), the third solution [AJ4763 ( NHO ₃ ): 14.4%, H ₂ O: 85.6%], and the fourth solution (H ₂ SO ₄ : 18.6%, H ₂ O: 81.4%) with pure water to obtain CrO ₃ : 3.8%, MP3: 0.8%, AJ4763 (NHO ₃ ): 19.2%, H ₂ SO ₄ : 7.6%), residual pure water: 71.6% Replenishment solution can be prepared, the color of which is blue-brown to black PH is less than 1, specific gravity is 1.208 ~ 1.308.

The solution thus prepared is opened and stored in the supply tank 2 through the mixed liquid supply pipe 9 by opening the mixing control valve 10, and then supplied to the circulation tank 3 through the supply liquid supply pipe 11 to replenish the initial chromium solution. Done. For example, when the available volume of the circulating tank 3 is (8 m) ³, the value obtained by multiplying the initial chromium solution by 0.935, that is, (8 × 0.935 = 7.48 l / min) using the metaring pump 12 '. Simultaneously with the discharge, the replenishment solution of the reference concentration stored in the supply tank 2 can be stably supplied into the circulation tank 3. In other words, the replenishment solution can be supplied as much as the amount of chromium solution discharged from the circulation tank.

Hereinafter, the present invention will be described in detail through examples.

(Example 1)

Using a solution supply device as shown in FIG. 1, hookrom treatment was performed to ensure corrosion resistance of the galvanized steel sheet. At this time, the composition components of the initial chromium solution circulated and supplied to the plating unit 15 through the circulating fluid supply pipe 14 in the circulation tank 3 of the device was as shown in Table 1 below.

And after electrochromic galvanized steel sheet using the initial chromium solution different from these components, the corrosion resistance, color, chromium adhesion amount, discoloration degree of the galvanized steel sheet was evaluated, the results are also shown in Table 1 The evaluation results indicate that ◎ is very good, O is good, □ is usually, △ is bad, and X is very bad.

On the other hand, the corrosion resistance in this experiment was evaluated as SST TEST (Salt Spray Test), the color was measured by the color gauge, the amount of chromium coating by the coating amount coating meta, the degree of discoloration through the outdoor exposure test.

Initial chromium solution composition (Vol.%) Characteristics CrO ₃ MP3 AJ4763 (NHO ₃ ) H ₂ SO ₄ pure Corrosion resistance color Adhesion discoloration Comprehensive Evaluation Inventive Example One 1.5-2.6 2.2 9 3.6 82.6 ~ 83.7 O O ◎ O ◎ 2 2.11 1.5 ~ 3.0 9 3.6 82.3 ~ 83.8 O O O ◎ ◎ 3 2.11 2.2 7.5-10.5 3.6 81.6-84.6 O O ◎ O ◎ 4 2.11 2.2 9 2.4 ~ 4.6 82.1 ~ 84.1 O ◎ O O ◎ Comparative example One One 2.2 9 3.6 84.2 △ △ X O X 2 2.11 One 9 3.6 83.3 △ O O X X 3 2.11 2.2 7 3.6 84.1 △ O △ O □ 4 2.11 2.2 9 2 83.5 △ X O △ X 5 3 2.2 9 3.6 82.2 O X X O X 6 2.11 3.5 9 3.6 81.8 △ △ O O △ 7 2.11 2.2 11 3.6 81.1 △ △ X △ X 8 2.11 2.2 9 5 81.7 O X □ □ X

As shown in Table 1, in the case of Inventive Examples (1 to 4) in which the initial chromium solution composition to hook the electro-galvanized steel sheet meets the scope of the present invention, it was possible to obtain a shiny steel surface. The surface is uniform and stable within the target range in terms of corrosion resistance, color, adhesion amount and discoloration.

In contrast, in Comparative Example (1), the CrO ₃ content was too small, and the amount of chromium adhered to the target. In addition, in Comparative Example (3) having excessive MP3 content, discoloration occurred in the edge portion of the hook-romed galvanized steel sheet, and in Comparative Example (6) where the content was too small, suspended matter (sludge) occurred in the Hook-Rom solution. .

In the Comparative Example (3) having less than 7.5% of AJ4763, Free Acid concentration and chromium adhesion amount were slightly lower than the target. In Comparative Example (7) having more than 10.5%, the free acid concentration was higher than the target. With this nickname, the amount of chromium attached was higher than the target.

In addition, the comparative example (4) having too little H ₂ SO ₄ content had a hazy color of the surface of the hook-romed steel sheet, and had too much yellowness in too many comparative examples (8).

(Example 2)

Hooking the electrogalvanized steel sheet using the initial chromium solution of the present invention of Example 1, the initial chromium solution of the circulation tank (3) by using a metaring pump 12 '7.48 lm ³ / min While discharging at a speed, a replenishment solution having a different composition was supplied into the circulation tank 3 as shown in Table 2 stored in the supply tank 2 by the amount thereof.

In addition, after the electroplated galvanized steel sheet was hook-romed using a replenishment solution having different ingredients, the corrosion resistance, color, chromium deposition amount, and discoloration degree of the galvanized steel sheet were evaluated, and the results are also shown in Table 1. The evaluation results indicate that ◎ is very good, O is good, □ is usually, △ is bad, and X is very bad.

On the other hand, the corrosion resistance in this experiment was evaluated as SST TEST (Salt Spray Test), the color was measured by the color gauge, the amount of chromium coating by the coating amount coating meta, the degree of discoloration through the outdoor exposure test.

Supply solution composition (Vol.%) Characteristics CrO ₃ MP3 AJ4763 (NHO ₃ ) H ₂ SO ₄ pure Corrosion resistance color Adhesion discoloration Comprehensive Evaluation Inventive Example One 3.6-4.0 0.8 19.2 7.6 68.4-68.8 O O O O O 2 3.8 0.6 ~ 1.2 19.2 7.6 68.2-68.8 O O O ◎ ◎ 3 3.8 0.8 18.2 ~ 20.2 7.6 67.6 ~ 69.6 O O ◎ O O 4 3.8 0.8 19.2 6.6-8.6 67.6 ~ 69.6 O ◎ O O ◎ Comparative example One 3 0.8 19.2 7.6 69.4 △ X X O X 2 3.8 0.4 19.2 7.6 69.0 △ O O X X 3 3.8 0.8 17 7.6 70.8 △ O △ O □ 4 3.8 0.8 19.2 6 (6.6) 70.2 △ X O △ X 5 4.5 0.8 19.2 7.6 67.9 O X X O X 6 3.8 1.5 19.2 7.6 67.9 △ △ O O △ 7 3.8 0.8 22 7.6 65.8 △ X X △ X 8 3.8 0.8 19.2 9 67.2 O X □ □ X

As shown in Table 2, in the case of the present invention Examples (1 to 4) in which the composition of the replenishment solution was optimally controlled, all were able to obtain a glossy steel surface, and the surface was uniform and corrosion resistance, color, and adhesion amount were In the discoloration part, it was stable within the target range.

In contrast, in Comparative Example (1), the amount of chromium was too low because the CrO ₃ content was too low, and in Comparative Example (6) in which the content was too much, the amount of chromium was too excessive. In addition, in Comparative Example (3) having excessive MP3 content, discoloration occurred in the edge portion of the hook-romed galvanized steel sheet, and in Comparative Example (6) in which the content was too small, suspended matter (sludge) occurred in the Hook-Rom solution. .

In the Comparative Example (3) having a content of AJ4763 of less than 18.2%, the free acid concentration and the amount of chromium deposition were slightly lower than the target. In Comparative Example (7), the content of which exceeded 20.2%, the free acid concentration was higher than the target. With this nickname, the amount of chromium deposited was greater than the target.

In addition, the comparative example (4) having too little H ₂ SO ₄ content had a hazy color of the surface of the hook-romed steel sheet, and had too much yellowness in too many comparative examples (8).

As described above, the present invention provides an initial chromium solution capable of hook-roming the electrogalvanized steel sheet, and also provides a replenishment solution that can replenish the chromium solution if necessary, so that it is stored in a humid area. Syrah is not discolored in the portion of the hook layer is plated, and the thickness and color of the plated layer is not only hook-romed uniformly, it is also useful to prevent discoloration of the product.

Claims (2)

Vol.%, CrO ₃ : 1.5 ~ 2.6%, MP3: 1.5 ~ 3.0%, AJ4763: 7.5 ~ 10.5%, H ₂ SO ₄ : 2.6 ~ 4.6%, The initial stage for chrome post-treatment of electro-galvanized steel sheet Hookrom solution. Vol.%, CrO ₃ : 3.6 ~ 4.0%, MP3: 0.6 ~ 1.2%, AJ4763: 18.2 ~ 20.2%, H ₂ SO ₄ : 6.6 ~ 8.6%, Electro zinc coated steel sheet consisting of balance pure water Ash solution.