WO2016075920A1

WO2016075920A1 - Method for manufacturing galvanized steel sheet

Info

Publication number: WO2016075920A1
Application number: PCT/JP2015/005583
Authority: WO
Inventors: 克弥星野; 平　章一郎; 古谷　真一
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2014-11-12
Filing date: 2015-11-09
Publication date: 2016-05-19
Also published as: KR20170067834A; EP3219826A4; US20170314138A1; JPWO2016075920A1; KR102007103B1; EP3219826A1; CN107109660A; MX2017006133A

Abstract

The present invention addresses the problem of providing a method for manufacturing a galvanized steel sheet, by which it is possible to remove oxides in the surface of the galvanized layer by contact with an alkaline aqueous solution, and prevent appearance issues caused by deposits deposited in the alkaline aqueous solution. In the method for manufacturing a galvanized steel sheet according to the first invention for solving said problem, the galvanized steel sheet has a reaction layer on the surface of the steel sheet. The reaction layer is an oxide layer containing a crystal structure represented by Zn₄(SO₄)_1-X (CO₃) _X(OH)₆∙nH₂O. As a pretreatment for forming the reaction layer, the galvanized steel sheet is brought into contact for 1.0 or more seconds with an alkaline aqueous solution that has a pH of at least 10.0 and contains a total of at least 0.050 mass% of one or more chelating agents selected from among sodium gluconate, sodium glucoheptonate, sodium citrate, tartaric acid, arabonic acid, galactonic acid, sorbitol, mannitol, glycerin, EDTA, and sodium tripolyphosphate.

Description

Method for producing galvanized steel sheet

The present invention relates to a method for producing a galvanized steel sheet having a reaction layer.

Zinc-based plated steel sheets are used in a wide range of applications, mainly in automobile bodies, home appliances, and building materials. With respect to galvanized steel sheets for such applications, a technique is known in which a reaction layer is provided on the surface of the steel sheet to improve properties such as press molding, corrosion resistance, and appearance.

However, the galvanized steel sheet before forming the reaction layer conventionally has an unnecessary oxide layer such as Zn having a thickness of less than 10 nm and Al being an impurity element in the outermost layer. This unnecessary oxide layer hinders the reactivity of chemical conversion treatment such as zinc phosphate treatment and chromate treatment, and it is necessary to set a long reaction time in order to form a sufficient reaction layer.

The increase in reaction time is accompanied by an increase in equipment costs and line length, and an increase in running costs such as electricity and gas.

On the other hand, a technique is known in which an unnecessary oxide layer present on the surface layer of a galvanized steel sheet is removed to reduce the reaction time by contacting with an alkaline aqueous solution before forming the reaction layer.

Patent Document 1 describes a technique in which a hot-dip galvanized steel sheet is contacted with an alkaline aqueous solution and then treated with a SiO ₂ -containing chromate solution.

Also known is a technique for intentionally forming an oxide film after treatment with an alkaline aqueous solution.

Patent Documents 2 and 3 describe techniques for forming an oxide layer after contacting a hot-dip galvanized steel sheet with an alkaline aqueous solution.

Patent Document 4 describes a technique for forming an oxide layer after bringing the surface of an alloyed hot-dip galvanized steel sheet into contact with an alkaline aqueous solution.

Patent Document 5 discloses a crystal structure represented by Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O after contacting the surface of a hot dip galvanized steel sheet with an alkaline aqueous solution. A technique for forming an oxide layer containing an object is described.

JP-A-5-279868 JP 2006-183074 A JP 2006-233280 A Japanese Patent Laying-Open No. 2005-97741 Japanese Patent Application No. 2015-530230

In the techniques of Patent Documents 1 to 5, the reaction time for providing a reaction layer by contact with an alkaline aqueous solution can be shortened. However, in a continuous processing apparatus that is normally used, Zn and Al precipitates deposited in an alkaline aqueous solution adhere to the deflector roll and the support roll, and the surface of the steel sheet is scratched, resulting in uneven appearance after the reaction layer is formed. It sometimes caused troubles in appearance.

The present invention has been made in view of such circumstances. Zinc-based plated steel sheet that can remove unnecessary oxide layers on the surface of the zinc-based plating layer by contact with an alkaline aqueous solution, and can avoid appearance problems due to precipitates that precipitate in the alkaline aqueous solution. It aims at providing the manufacturing method of.

The present inventors have intensively studied to solve the above problems. As a result, the inventors have found that the above problem can be solved by adding a specific chelating agent to the alkaline aqueous solution used before forming the reaction layer, and have completed the present invention. More specifically, the present invention provides the following.

The method for producing a zinc-based plated steel sheet according to the first invention for solving the above-mentioned problem is a method for producing a zinc-based plated steel sheet having a reaction layer on the surface of the steel sheet, and the reaction layer is Zn ₄ (SO ₄ ). _1-X (CO ₃ ) _X (OH) ₆ · nH ₂ O is an oxide layer containing a crystal structure, and as a pretreatment for forming the reaction layer, sodium gluconate, sodium glucoheptonate, Contains at least 0.050 mass% of a total of one or more chelating agents selected from sodium acid, tartaric acid, arabonic acid, galactonic acid, sorbit, mannitol, glycerin, EDTA, sodium tripolyphosphate, and has a pH of 10.0 or more The zinc-based plated steel sheet is brought into contact with an alkaline aqueous solution for 1.0 second or longer.

The method for producing a zinc-based plated steel sheet according to the second invention for solving the above problem is the method for producing a zinc-based plated steel sheet according to the first invention, wherein the pH of the alkaline aqueous solution is 12.6 or more. It is characterized by that.

According to the present invention, the oxide on the surface of the zinc-based plating layer can be satisfactorily removed by contact with an alkaline aqueous solution. In addition, in the alkali treatment for shortening the reaction layer formation time, precipitates of Al and Zn and the like can be reduced, and a galvanized steel sheet having a reaction layer with a good appearance can be obtained.

FIG. 1 is a schematic diagram showing evaluation criteria for evaluating appearance unevenness.

Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment. In the present invention, the zinc-based plated steel sheet is a steel sheet having a coating mainly composed of zinc on the surface of the steel sheet regardless of the production method, such as a zinc-plated steel sheet, a zinc alloy-plated steel sheet, and a plated steel sheet in which particles are dispersed in zinc. Is included. That is, the zinc-based plating layer includes a zinc plating layer, a zinc alloy plating layer, a plating layer in which particles are dispersed in zinc, and the like.

The present invention provides a reaction layer that can satisfactorily remove an unnecessary oxide layer present on the surface of a zinc-based plating layer, that is, Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ It is a method for producing a zinc-based plated steel sheet having an oxide layer containing a crystal structure represented by O. The present invention includes, for example, a step of applying zinc plating, a step of contacting with an alkaline aqueous solution, and a crystal structure represented by Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O Forming an oxide layer containing an object. Hereinafter, each step will be described.

-Zinc-based plating process-
First, the process of applying zinc-based plating will be described. In the step of applying zinc-based plating, the method of applying zinc plating is not particularly limited, and general methods such as hot dip galvanizing and electrogalvanizing can be employed. Moreover, the process conditions of electrogalvanization and hot dip galvanization are not specifically limited, What is necessary is just to employ | adopt preferable conditions suitably. In addition, when performing hot dip galvanization, it is preferable from the viewpoint of dross countermeasure that Al is added in the plating bath. In this case, elemental components other than Al are not particularly limited. That is, even if Pb, Sb, Si, Sn, Mg, Mn, Ni, Ti, Li, Cu or the like is contained in addition to Al, the effect of the present invention is not impaired.

Here, the steel type of the steel sheet to be galvanized is not particularly limited, and various steel sheets such as a low carbon steel, an ultra low carbon steel, an IF steel, and a high strength steel sheet added with various alloy elements should be used. Can do. Moreover, both a hot-rolled steel plate and a cold-rolled steel plate can be used as the steel plate. The thickness of the steel plate is not particularly limited. From the viewpoint of use in applications such as automobile bodies, home appliances, and building materials, 0.4 to 5.0 mm is preferable.

Furthermore, in the step of applying zinc-based plating, an alloyed hot-dip galvanized steel sheet that has been subjected to alloying treatment after hot-dip galvanizing may be used. In the present invention, the conditions for the alloying treatment are not particularly limited, and preferable conditions may be adopted as appropriate.

-Step of contact with alkaline aqueous solution-
After the zinc plating treatment is performed, a contact treatment using an alkaline aqueous solution is performed. The alkaline aqueous solution used in this contact treatment has a pH of 10.0 or higher. If the pH is less than 10.0, the removal of the oxide layer becomes insufficient. When the pH is 12.6 or more, the contact time with the alkaline aqueous solution can be shortened, which is effective and preferable.
On the other hand, pH of 14.0 or less is preferable from the viewpoint of preventing dissolution of the zinc-based plating layer and preventing blackening of the surface appearance.

The alkaline aqueous solution contains a total of 0.050 mass% or more of a specific chelating agent. When the deposits of Al and Zn increase in the alkaline aqueous solution, the appearance of the liquid becomes a suspension. In the present invention, 0.055 mass% or more of a chelating agent is contained in an alkaline aqueous solution, and precipitates of Al and Zn are reduced.

The chelating agent is at least one selected from sodium gluconate, sodium glucoheptonate, sodium citrate, tartaric acid, arabonic acid, galactonic acid, sorbit, mannitol, glycerin, EDTA, and sodium tripolyphosphate. From the viewpoint of being able to chelate Al and Zn and being inexpensive, the chelating agent is preferably sodium gluconate.

If the total content of chelating agents in the alkaline aqueous solution is less than 0.050 mass%, the increase in the solubility of Al or Zn in the alkaline aqueous solution becomes insufficient. From the viewpoint of reducing precipitates in the alkaline aqueous solution, the amount of the chelating agent contained in the alkaline aqueous solution is preferably 0.100 mass% or more. On the other hand, from the viewpoint of drug cost, the amount of chelating agent contained in the alkaline aqueous solution is preferably 10.0 mass% or less.

From the viewpoint of shortening the contact time between the alkaline aqueous solution and the steel sheet, the temperature of the alkaline aqueous solution is preferably in the range of 20 ° C. to 70 ° C., more preferably 40 ° C. to 70 ° C.

¡The type of alkali builder is not limited. It is preferable to use chemicals such as NaOH from the viewpoint of cost reduction. In order to achieve the desired pH of the alkaline aqueous solution, the amount of alkali builder is appropriately adjusted. Further, the alkaline aqueous solution may contain substances other than the elements contained in the zinc-based plating solution such as Zn, Al, Fe, and other components.

There is no particular limitation on the method of bringing the alkaline aqueous solution into contact with the zinc-based plated steel sheet (particularly, the oxide layer on the surface layer thereof). There is a method of contacting a plated steel sheet.

The time for contacting the galvanized steel sheet with the alkaline aqueous solution is 1.0 second or more. When the contact time is less than 1.0 second, the oxide on the surface of the zinc-based plating layer cannot be sufficiently removed, and thus the reaction time for providing the reaction layer is not sufficiently shortened. From the viewpoint of equipment cost and productivity, the time for contacting the zinc-based plated steel sheet with the alkaline aqueous solution is preferably 10.0 seconds or less.

In the present invention, temper rolling may be performed either after the step of applying zinc-based plating and before or after the alkaline aqueous solution treatment. Since the site | part which contacted the temper rolling roll in a steel plate removes the unnecessary oxide layer of Al and Zn which exists in the surface of a zinc-type plating layer by contact with a roll, the reactivity becomes high.

-Process of forming reaction layer-
Usually, the steel sheet is brought into contact with an alkaline aqueous solution and then washed and dried, and then the reaction layer, that is, Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O A treatment for providing an oxide layer containing a crystalline structure is performed.

In the present invention, the oxide layer containing a crystal structure represented by Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O is a zinc-based plating and chemical treatment solution. Is a layer of a reaction product formed on the surface of the steel sheet due to contact and chemical reaction. As a treatment for forming an oxide layer containing a crystal structure represented by Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O, for example, a zinc-based plated steel sheet is treated with sulfuric acid. Contact with an acidic solution containing ions, hold for 1 to 60 seconds, and then wash with water. Contact the surface of the oxide layer formed in the oxide layer forming step with an alkaline aqueous solution. The neutralization process process which carries out washing | cleaning and drying after that for 0.5 second or more in the state made to carry out is performed. The alkaline aqueous solution may contain 0.01 g / L or more of P ions as a P concentration and 0.1 g / L or more of carbonate ions as a carbonate ion concentration. The present invention is not limited to this treatment method as long as the crystal structure represented by Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O exists on the surface of the steel sheet. is not.

Hereinafter, the present invention will be described with reference to examples. The technical scope of the present invention is not limited to the following examples.

Temper rolling was performed on a steel sheet obtained by subjecting a cold-rolled steel sheet having a thickness of 0.7 mm and a width of 1100 mm to a hot dip galvanizing treatment. Subsequently, as a treatment for removing the oxide layer, the steel sheet was contacted with an alkaline aqueous solution adjusted to the conditions shown in Tables 1-1 and 1-2 for a specified time, washed with water, and dried.

A steel sheet obtained by subjecting a cold-rolled steel sheet having a thickness of 0.7 mm and a width of 1100 mm to hot dip galvanization and alloying, and a temper rolling of the steel sheet, and a thickness of 0.7 mm and a width of 1100 mm The cold-rolled steel sheet subjected to electrogalvanization treatment was brought into contact with an alkaline aqueous solution in the same procedure, then washed with water and dried.

For the zinc-based plated steel sheet obtained as described above, the thickness of the unnecessary oxide layer on the surface of the zinc-based plating layer after the alkaline aqueous solution treatment and the appearance unevenness after the formation of the reaction layer are evaluated and included in the alkaline aqueous solution. Suspension material (SS) was measured. In addition, pH of alkaline aqueous solution was measured with the commercially available glass electrode.

Subsequently, as an oxide layer forming treatment including a crystal structure represented by Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O, 30 g of sodium acetate trihydrate was added. The steel sheet was immersed in a sulfuric acid solution containing / L and adjusted to pH 1.5, squeezed with a roll, and held for 10 seconds. Next, it was washed with water and dried. Subsequently, neutralization was performed with a treatment solution containing sodium pyrophosphate 9.8 g / L and sodium carbonate decahydrate 0.48 g / L.

(1) Measurement of unnecessary oxide layer thickness After contact with the alkaline aqueous solution, a fluorescent X-ray analyzer was used to measure the thickness of the unnecessary oxide layer formed on the galvanized steel sheet. If the thickness (oxide film thickness) of the oxide layer is 4 nm or less, it can be evaluated that the reaction time for providing the reaction layer is shortened. If it is 2 nm or less, it can be evaluated that the reaction time is further shortened.

The voltage and current of the tube at the time of measurement were 30 kV and 100 mA, the spectroscopic crystal was set to TAP, and the O-Kα ray was detected. When measuring the O—Kα ray, in addition to the peak position, the intensity at the background position was also measured so that the net intensity of the O—Kα ray could be calculated. The integration time at the peak position and the background position was 20 seconds, respectively.

A silicon wafer on which a silicon oxide film having a thickness of 96 nm, 54 nm, and 24 nm, which has been cleaved to an appropriate size, is set on the sample stage together with these series of samples. -The intensity of Kα rays can be calculated. Using these data, a calibration curve between the oxide layer thickness and the OKα line intensity is created, and the oxide layer thickness of the test material is calculated as the oxide layer thickness in terms of silicon oxide film. I made it.

(2) Evaluation of appearance unevenness and oxide film thickness after surface oxidation treatment Treatment for forming an oxide layer on the surface of hot-dip galvanized steel sheet, alloyed hot-dip galvanized steel sheet, and electrogalvanized steel sheet contact-treated with an alkaline aqueous solution Then, the appearance unevenness was evaluated by visual observation and microscopic observation. That is, a solution in which an aqueous solution containing ferrous sulfate 5.0 g / L and sodium acetate heptahydrate 50 g / L was adjusted to pH 2.0 with sulfuric acid was prepared, and this treatment solution was contact-treated with an alkaline aqueous solution. The various plated steel sheets were applied to a thickness of 3 μm, held for 10 seconds, then washed with water and dried to form an oxide layer. The observation area is 70 mm × 150 mm. Based on the appearance sample shown in FIG. 1, 1 to 5 points were assigned for evaluation. Four points indicate that it is good, and five points indicate that it is even better.

(3) Measurement of suspended solids (SS) An alkaline aqueous solution after the treatment of the zinc-based plated steel sheet 100t was collected and suction filtered using a membrane filter having a pore diameter of 1 μm. The filtered material was dried at 110 ° C., and the weight was measured and converted to mg / L. The production amount at which this value exceeded 10 mg / L was recorded. If the amount of steel sheet processing exceeding 10 mg / L is 3000 t or more, it can be evaluated as favorable from the viewpoint of productivity. Those that did not exceed 10 mg / L even after 5000 t treatment were evaluated as having no suspended solids (denoted as “> 5000” in Tables 1-1 and 1-2). No. No treatment with alkaline aqueous solution. 1, 54 and 56 did not make this measurement.

The results obtained from the above are shown in Tables 1-1 and 1-2. In addition, No. 15 and No. No. 41 is the same test condition. 20 and no. 28 is the same test condition.

Table 1-1 and 1-2 show the following matters.

No. 1 to 57 were subjected to surface analysis after removing an unnecessary oxide layer with an alkaline aqueous solution.

No. No contact treatment with alkaline aqueous solution. In Comparative Examples 1, 54 and 56, the thickness of the oxide layer is 7 to 10 nm, and it cannot be removed sufficiently.

No. Although 2 and 3 are performing contact with alkaline aqueous solution, they are insufficient examples (comparative examples) in that no chelating agent is added to the alkaline aqueous solution. The oxide layer can be sufficiently removed. However, when the production amount of the steel sheet increases, suspended substances are generated in the alkaline aqueous solution and the appearance is deteriorated.

No. 4 and 11 are examples (comparative examples) in which the concentration of the chelating agent is insufficient, although the contact with the alkaline aqueous solution containing the chelating agent is performed. The oxide layer can be sufficiently removed. However, when the production amount of the steel sheet increases, suspended substances are generated in the alkaline aqueous solution.

No. 19 and 23 are examples (comparative examples) in which the contact time is short although the contact with the alkaline aqueous solution containing the chelating agent is carried out. The oxide layer has a thickness of 6 to 7 nm and cannot be removed sufficiently.

No. Nos. 27 and 34 are examples (comparative examples) in which the pH is low although contact with an alkaline aqueous solution containing a chelating agent is carried out. The thickness of the oxide layer is 7 nm and cannot be removed sufficiently.

No. 24 and 28 to 33 are examples of the present invention in which the influence of pH was confirmed at a contact time of 1.0 second. When the pH is 12.6 or more, the oxide film can be removed to 2 nm or less even when the contact time is 1.0 second, and the reaction time for providing the reaction layer can be further shortened.

No. With respect to 2 to 53, 55, and 57, an oxide layer including a crystal structure represented by Zn ₄ (SO ₄ ) _1-X (CO ₃ ) _X (OH) ₆ .nH ₂ O was analyzed.

_{_{_{_{(4) Zn 4 (SO 4}}}} ) in _{1-X (CO 3) X} (OH) 6 · nH 2 O Checking _{_{_{_{Zn 4 (SO 4) 1-}}}} X (CO 3) X (OH) 6 · nH 2 O The surface of the oxide layer containing the crystal structure represented is rubbed with a stainless steel brush with a diameter of 0.15 mm and a length of 45 mm and ethanol, and the resulting ethanol solution is suction filtered to powder the film components. Extracted as a component. The film component collected as a powder was subjected to temperature analysis using a gas chromatograph mass spectrometer to perform quantitative analysis of C. A pyrolysis furnace was connected to the front stage of the gas chromatograph mass spectrometer. About 2 mg of the powder sample collected in the pyrolysis furnace was inserted, and the gas generated in the pyrolysis furnace was raised from 30 ° C to 500 ° C at a heating rate of 5 ° C / min. Helium was transported into a gas chromatograph mass spectrometer and analyzed for gas composition. The column temperature at the time of GC / MS measurement was set to 300 ° C.

Presence form of C Similarly, the coating component collected by pulverization was analyzed using gas chromatography bluff mass spectrometry, and the presence form of C was analyzed.

Presence form of Zn, S, O, H The presence form of S, Zn, O was analyzed using an X-ray photoelectron spectrometer. Using an Al Ka monochromatic radiation source, narrow measurement of the spectrum corresponding to Zn LMM, S 2p was performed.

Presence form of P The presence state of P was analyzed using an X-ray absorption fine structure apparatus. Measurement of ZAFS (X-ray absorption fine structure) was carried out at room temperature in the beam line BL27A of Photon Factory of the High Energy Accelerator Research Organization. The degreased sample surface was irradiated with monochromated synchrotron radiation, and the absorption edge XANES (structure near the X-ray absorption edge) spectrum of the PK shell was measured by the total electron yield method (TEY) based on the sample absorption current measurement.

[Correction based on Rule 91 26.11.2015]
Determination of water of crystallization The weight loss of 100 ° C. or less was measured using a differential thermobalance. About 15 mg of powder sample was used for the measurement. After the sample was introduced into the apparatus, the temperature was raised from room temperature (about 25 ° C.) to 1000 ° C. at a rate of temperature rise of 10 ° C./min, and the thermogravimetric change at the time of temperature rise was recorded.

Identification of Crystal Structure X-ray diffraction was performed on the film components collected by pulverization in the same manner, and the crystal structure was estimated. Cu was used as a target, and measurement was performed under the conditions of an acceleration voltage of 40 kV, a tube current of 50 mA, a scan speed of 4 deg / min, and a scan range of 2 to 90 °.

Hereafter, No. The results obtained for 2 to 38, 40 to 53, 55 and 57 will be described.

As a result of gas chromatograph mass spectrometry, it was confirmed that CO ₂ was released between 150 ° C. and 500 ° C., and C was present as a carbonate.

As a result of analysis using an X-ray photoelectron spectrometer, a peak corresponding to Zn LMM was observed in the vicinity of 987 eV, and it was found that Zn was present as zinc hydroxide. Similarly, a peak corresponding to S 2p was observed in the vicinity of 171 eV, indicating that S exists as a sulfate.

As a result of analysis using an X-ray absorption fine structure apparatus, peaks were observed in the vicinity of 2153, 2158, 2170 eV, and it was found that P was present as pyrophosphate.

[Correction based on Rule 91 26.11.2015]
From the results of the differential thermal balance, it was found that a weight loss of 11.2% was observed at 100 ° C. or lower, and it contained crystal water.

As a result of X-ray diffraction, 2θ is 8.5 °, 15.0 °, 17.4 °, 21.3 °, 23.2 °, 26.3 °, 27.7 °, 28.7 °, 32. Diffraction peaks are observed around 8 °, 34.1 °, 58.6 °, and 59.4 °.

To contain the above results and the composition ratio, the crystal structure material from a charge _balance, represented by _{_{_{Zn 4 (SO 4) 0.95 (}}} CO 3) 0.05 (OH) 6 · 3.3H 2 O I understand.

No. A detailed film analysis of No. 39 was conducted.

[Correction based on Rule 91 26.11.2015]
From the results of the differential thermobalance, it was found that a weight loss of 9.4% was observed at 100 ° C. or lower, and it contained crystal water.

As a result of X-ray diffraction, 2θ is 8.8 °, 15.0 °, 17.9 °, 21.3 °, 23.2 °, 27.0 °, 29.2 °, 32.9 °, 34. A diffraction peak is observed around 7 ° and 58.9 °.

To contain the above results and the composition ratio, the crystal structure material from a charge _balance, the _{_{_{_{Zn 4 (SO 4) 0.8 (}}}} CO 3) represented by _{_{0.2 (OH) 6 · 2.7H 2}} O I understand.

Claims

A method for producing a zinc-based plated steel sheet having a reaction layer on the surface of the steel sheet, wherein the reaction layer is a crystal represented by Zn 4 (SO 4 ) 1-X (CO 3 ) X (OH) 6 .nH 2 O An oxide layer containing a structure, and as a pretreatment for forming the reaction layer, sodium gluconate, sodium glucoheptate, sodium citrate, tartaric acid, arabonic acid, galactonic acid, sorbit, mannitol, glycerin, EDTA, tripolylin Zinc, characterized by bringing a zinc-based plated steel sheet into contact with an alkaline aqueous solution containing 0.050 mass% or more of a total of one or more chelating agents selected from sodium acid and having a pH of 10.0 or more for 1.0 second or more Manufacturing method of a galvanized steel sheet.
The method for producing a galvanized steel sheet according to claim 1, wherein the pH of the alkaline aqueous solution is 12.6 or more.