KR100544499B1 - Solution for Forming Moly-Phosphate Coating on The Galvanized Steel Sheet with High Corrosion Resistance and Methods for Manufacturing Moly-Phosphate Treated Steel Sheet and Resin Coated Steel Sheet with High Corrosion Resistance Using the Solution - Google Patents

Abstract

The present invention relates to a technique for performing an environmentally friendly chemical conversion treatment using a zinc plated steel sheet, which is a surface-treated steel sheet, which not only shortens the reaction time for forming a molybphosphate film but also ensures excellent corrosion resistance even upon resin coating. An object of the present invention is to provide a method for forming a molten phosphate coating film for a plated steel sheet and a method for producing a molten phosphate treated steel sheet using the solution and a resin coated steel sheet.

In the present invention, the molar ion: 17-25 g / l, the phosphoric acid: 15-55 g / l, the nitrate ion: 8-50 g / l, the hydrogen silicate: 2-8 g / l, and 3 methyl 5 pyrozoline: 1-25 g The glyph phosphate film-forming solution for galvanized steel sheet containing / l and water as a solvent, and a method for producing a molten phosphate-treated steel sheet using this solution and a method for producing a resin coated steel sheet are included.

Galvanized Steel Sheet, Environment-Friendly, Resin Coated Steel Sheet, Chrome Free, Molyphosphate,

Description

Molten phosphate film-forming solution for galvanized steel sheet, and a method for producing a corrosion resistant molybdate-treated steel sheet using this solution and a method for producing a resin coated steel sheet with excellent corrosion resistance {Solution for Forming Moly-Phosphate Coating on The Galvanized Steel Sheet with High Corrosion Resistance and Methods for Manufacturing Moly-Phosphate Treated Steel Sheet and Resin Coated Steel Sheet with High Corrosion Resistance Using the Solution}

The present invention relates to a technique for performing an environmentally friendly chemical conversion treatment using a galvanized steel sheet, which is a surface-treated steel sheet, and more specifically, a solution for forming an environmentally friendly molybphosphate film on a galvanized steel sheet and corrosion resistance using the solution. The present invention relates to a method for producing an excellent molybphosphate-treated steel sheet and a method for producing a resin coated steel sheet excellent in corrosion resistance.

The morphophosphate coating is an environmentally friendly chromium-free coating that is harmless to humans and the environment.

The molybdate film has been researched as a replacement of the existing chromate film, but it has a technical limitation in reducing reaction time and improving corrosion resistance, making it difficult to produce in a continuous line such as steel mill.

As the prior art related to the molybphosphate coating, Japanese Patent Laid-Open Publication No. 71-6846, Japanese Patent Laid-Open Publication No. 71-2419, Japanese Patent Application Publication No. 76-14141 and the like are known.

Japanese Laid-Open Patent Publication No. 71-6846 discloses a method for forming a molybdate film containing 0.05 to 45 wt% of a water-soluble organic compound at a molybdate concentration of 0.5 mol or less, and the Japanese Laid-Open Patent Publication 76-2419 No. relates to immersion methods, in which magnesium or ammonium molybdate solutions of 0.025 to 0.02 M are presented.

In addition, Japanese Patent Publication No. 76-14141 relates to an immersion method, and a molybdate solution containing ammonium sulfate has been presented.

However, the above-described prior arts have a problem in that a long time is required to form the molybdate film and the corrosion resistance is not excellent.

In addition, Bech-Nielsen is a technology for forming a phosphate coating by applying an oxidation current of -2.5 to +5.0 V (vs. SHE) to a subject under Mo concentrations of 2.9 to 9.8 g / l and Mo / P of 0.2 to 0.8. (WO 93-10278).

However, in this case, too, the reaction time is more than 2 minutes and corrosion resistance is known to be inferior to the conventional chromated steel sheet.

The present inventors, in relation to the above-described technology of forming a phosphate coating, Korean Patent Registration No. 256355 and Korean Patent Application No. 97-63082, Korean Patent Application No. 97-72731, and Korean Patent Application No. 97-732731 Has developed and applied for a patent.

The above-mentioned US Patent Registration No. 256355 and Korean Patent Application No. 97-63082 disclose a molybdate treatment technique for reducing reaction time, but the inferior corrosion resistance, and also after the resin is applied, that is, corrosion resistance, blackening resistance It does not describe etc.

The Korean Patent Application No. 97-72731 and the Korean Patent Application No. 97-732731 disclose molybdate treatment technology for securing reaction time and corrosion resistance. Although the corrosion resistance of the film has been secured to some extent compared with the existing chromate film, it has technical limitations such as inferior corrosion resistance due to the hygroscopicity of the molybphosphate film when the resin is applied to secure fingerprint and lubricity.

The present inventors conducted research and experiments to solve the above-mentioned problems of the prior art, and based on the results, the present invention proposes the present invention, and the present invention not only reduces the reaction time for forming a phosphate film but also a resin. An object of the present invention is to provide a molten phosphate film-forming solution for galvanized steel sheet and a method for producing a molten phosphate-treated steel sheet using the solution and a method for manufacturing a resin coated steel sheet which can ensure excellent corrosion resistance even when coated.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

In the present invention, the molar ion: 17-25 g / l, the phosphoric acid: 15-55 g / l, the nitrate ion: 8-50 g / l, the hydrogen silicate: 2-8 g / l, and 3 methyl 5 pyrozoline: 1-25 g The present invention relates to a molten phosphate film-forming solution for galvanized steel sheet containing / l and containing water as a solvent.

In addition, the present invention provides molybions: 17 to 25 g / l, phosphoric acid: 15 to 55 g / l, nitrates: 8 to 50 g / l, hydrogen silicate: 2 to 8 g / l, and 3 methyl 5 pyrozoline: 1 The molybdate film forming solution for galvanized steel sheet containing ˜25 g / l and containing water as a solvent was maintained at 40 to 80 ° C. to treat the galvanized steel sheet in a conventional manner to form a molybdate film on the galvanized steel sheet. It relates to a method for producing a molten phosphate treated steel sheet.

In addition, the present invention provides molybions: 17 to 25 g / l, phosphoric acid: 15 to 55 g / l, nitrates: 8 to 50 g / l, hydrogen silicate: 2 to 8 g / l, and 3 methyl 5 pyrozoline: 1 The molybdate film-forming solution for galvanized steel sheet containing ˜25 g / l and containing water as a solvent was maintained at 40 to 80 ° C., and then coated on the galvanized steel sheet in a conventional manner to form a molten phosphate film. It relates to a method for producing a resin coated steel sheet covering the.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The plated steel sheet to which the molybdate film forming solution of the present invention can be applied may be a galvanized steel sheet, which is a surface-treated steel sheet, preferably an electrogalvanized steel sheet.

In the molybdate film-forming solution, when the content of the molybdenum ion is 17g / l or less, the molybdate film is formed, but the corrosion resistance is poor, and when the content is 25g / l or more, the molybdate film may be formed but the surface appearance is poor. Therefore, it is preferable to set the content of the moly ions to 17 ~ 25g / l,

Phosphoric acid, nitrate ions, and hydrogen fluoride (H ₂ SiF ₆ ) are components added to improve the reactivity, and when added below the lower limit of the concentration of each ion, sufficient reactivity cannot be obtained to obtain a molybdate film. It takes a long time, and when the concentration of each ion is added above the upper limit, it is too reactive, so that dissolution of the plating layer of the galvanized steel sheet used as the base of the molybphosphate coated steel sheet is severely generated and the surface appearance is poor. The respective contents of nitrate ions and hydrogen silicate are preferably set to 15 to 55 g / l, 8 to 50 g / l, and 2 to 8 g / l.

In addition, if the addition amount of 3 methyl 5 pyrozoline is too small, the effect of addition is not obtained, if the addition of too much, it is rather a factor that deteriorates the film formation and corrosion resistance, so the addition amount of the 3 methyl 5 pyrozoline is It is preferable to set it to 1-25 g / l.
In the solution for forming a molten phosphate film for galvanized steel sheet of the present invention, the solvent is water.

When the molybdate film-forming solution is formed on the galvanized steel sheet by using the above-described molybdate film forming solution for galvanized steel sheet of the present invention, the molybdate film-forming solution is formed at a constant temperature, preferably 40 to 40 ° C. It is preferable to hold | maintain at 80 degreeC and to process.

If the solution temperature is 40 ° C or less, the corrosion resistance is deteriorated due to the delay of the formation of the molle film, and if the solution temperature is 80 ° C or more, there is a problem in that the molten film formed due to environmental degradation of the work and overreaction of the solution.

The resin coated steel sheet according to the present invention is prepared by forming a molybdate film as described above and then coating the resin by a conventional method.

The resin is not particularly limited, and any resin can be used as long as it is commonly used in the art, and may be appropriately selected in consideration of rubbing and / or lubricity.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Example 1)

After preparing a molten phosphate film-forming solution having a composition as shown in Table 1, the solution was maintained at 45 ℃ to treat the galvanized steel sheet with a galvanized coating amount of 20g / m ² to form a phosphate coating film, corrosion resistance, surface The appearance, resin coating property, blackening resistance and film formation time were evaluated, and the results are shown in Table 1 below.

The surface appearance was measured by using a color difference meter to measure the surface color of the white light and the corrosion resistance was evaluated by the time required to generate 5% of white blue according to ASTM B-117 standard.

Example No. Molyion (g / l) Phosphoric Acid (g / l) Nitrate Ion (g / l) Hydrogen fluoride (g / l) 3 methyl 5 pyrroline (g / l) Corrosion Resistance (SST, hrs) Surface appearance                                              Resin coating Black degeneration Encapsulation time Inventive Example One 18 40 25 5 5 180 ◎ ◎ ◎ ◎ 2 20 40 25 5 5 180 ◎ ◎ ◎ ◎ 3 25 40 25 5 5 180 ◎ ◎ ◎ ◎ Comparative example 4 6 40 25 5 5 60 × ○ × × 5 30 40 25 5 5 50 × × × △ Inventive Example 6 20 40 25 5 5 180 ◎ ◎ ◎ ◎ 7 20 35 25 5 5 180 ◎ ◎ ◎ ◎ 8 20 20 25 5 5 180 ◎ ◎ ◎ ◎ Comparative example 9 20 10 25 5 5 55 × ○ × × 10 20 55 25 5 5 50 × △ × △ Inventive Example 11 20 35 15 5 5 180 ◎ ◎ ◎ ◎ 12 20 35 25 5 5 180 ◎ ◎ ◎ ◎ 13 20 35 40 5 5 180 ◎ ◎ ◎ ◎ Comparative example 14 20 35 5 5 5 55 × ○ × × 15 20 35 55 5 5 50 × △ × △ Inventive Example 16 20 35 25 3 5 180 ◎ ◎ ◎ ◎ 17 20 35 25 5 5 180 ◎ ◎ ◎ ◎ 18 20 35 25 7 5 180 ◎ ◎ ◎ ◎ Comparative example 19 20 35 25 One 5 55 × ○ × × 20 20 35 25 13 5 50 × △ × △ Inventive Example 21 20 35 25 5 3 180 ◎ ◎ ◎ ◎ 22 20 35 25 5 5 180 ◎ ◎ ◎ ◎ 23 20 35 25 5 7 180 ◎ ◎ ◎ ◎ Comparative example 24 20 35 25 5 One 55 △ ○ △ × 25 20 35 25 5 13 50 × × × △    ◎: Excellent, ○: Good, △: Normal,: Poor

As shown in Table 1, in the case of the invention example (1 to 3, 6 to 8, 11 to 13, 16 to 18, 21-23) using a molybdate film-forming solution according to the present invention, the corrosion resistance, surface appearance , Resin coating resistance, blackening resistance and film formation time are all excellent, while the comparative example using a molten phosphate coating solution that does not satisfy the scope of the present invention (4,5,9,10,14,15, 19, 20, 24 and 25) it can be seen that all of the above properties are not satisfied.

(Example 2)

The molybdate film-forming solution of Inventive Example 22 of Example 1 was changed as shown in Table 2 below to form a molybdate film on an electrogalvanized steel sheet having a zinc plating amount of 20 g / m ² , and then coated with a resin. Corrosion resistance was evaluated and the results are shown in Table 2 below.

division Treatment temperature (℃) Corrosion Resistance (SST) Inventive Example 26 45 ◎ 27 65 ◎ 28 75 ◎ Comparative example 29 35 × 30 85 ×

As shown in Table 2, in the case of the invention examples (26, 27, 28) in which the molybdate film-forming solution according to the present invention was maintained at a temperature range consistent with the present invention to form a molybphosphate film, the corrosion resistance was excellent. On the other hand, in the case of Comparative Examples (29, 30) outside the solution holding temperature of the present invention it can be seen that the corrosion resistance is poor.

As described above, the present invention provides a molten phosphate coating solution for galvanized steel sheet that is chromium-free and harmless to humans and the environment, thereby reducing the reaction time for forming the molybdate film and improving the corrosion resistance. The steel sheet and the resin coated steel sheet has an effect that can be provided more economically.

Claims (3)

Molyion: 17 to 25 g / l, Phosphoric acid: 15 to 55 g / l, Nitrate: 8 to 50 g / l, Hydrogen fluoride: 2 to 8 g / l, and 3 methyl 5 pyrozoline: 1 to 25 g / l Solution for forming molybdate film for galvanized steel sheet containing water and containing water as solvent A method for producing a molybdate-treated steel sheet having excellent corrosion resistance to form a molybdate film on a galvanized steel sheet by treating the galvanized steel sheet by maintaining the molten phosphate film forming solution for galvanized steel sheet of claim 1 at 40 ~ 80 ℃ The method for producing a resin coated steel sheet having excellent corrosion resistance to coat a resin after forming a molybdate film on a galvanized steel sheet by treating the galvanized steel sheet by maintaining the molten phosphate film forming solution for galvanized steel sheet of claim 1 at 40 to 80 ℃.