JP2003253463A - Nonchromium treatment for galvanized steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively form a nonchromium film which can exhibit corrosion resistance, weldability and finish coating properties equal to above those of the conventional chromate film on the surface of a galvanized steel sheet. <P>SOLUTION: A treatment solution consisting of an aqueous solution of pH 2.0 to 6.5 which contains a water soluble resin (a) consisting of polymer molecules having a repeated unit expressed by the formula (1), and at least either a titanium compound of a zirconium compound (b), and can contain a silane coupling agent (c), and does not contain chromium is applied, and drying is performed at 50 to 200°C, so that a film is formed; in the formula (1), Y<SB>1</SB>and Y<SB>2</SB>are respectively, individually, a hydrogen atom or a Z group expressed by the following formula (2) or (3); and R<SB>1</SB>, R<SB>2</SB>, R<SB>3</SB>, R<SB>4</SB>and R<SB>5</SB>are respectively, individually, a hydrogen atom, a 1 to 10C alkyl group or a 1 to 10C hydroxyalkyl group, and the mean substitution number of the Z group per benzene ring in the polymer molecules is 0.2 to 1.0. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chromium-free galvanized steel sheet suitable as a material used for home electric appliances, switchboards, telephone exchange panels, automobile parts, building materials and the like. The present invention also relates to a chromium-free treatment liquid therefor and a method for producing a chromium-free galvanized steel sheet surface-treated using the treatment liquid.

[0002]

2. Description of the Related Art Zinc-based plated steel sheets plated with pure zinc or zinc alloy (in the present invention, zinc-coated steel sheets and zinc alloy-plated steel sheets are collectively referred to as zinc-based plated steel sheets) are painted and unpainted. In many cases, chromate treatment is often performed for the purpose of enhancing corrosion resistance, especially in zinc-based plated steel sheets for home appliances.

However, the chromate treatment liquid used for this treatment contains hexavalent chromium which is harmful to the human body, and is disadvantageous in terms of the working environment during treatment and the waste liquid treatment. For reasons such as being troublesome, it has been recommended to use a chromium-free treatment liquid for the surface treatment of the zinc-based plated steel sheet.

As a surface treatment method which is an alternative to the chromate treatment in the case of no coating, treatment with a treatment liquid containing tannic acid containing polyhydric phenolcarboxylic acid as an active ingredient is well known. When a metallic material is treated with an aqueous tannic acid solution,
The protective film formed by the reaction between tannic acid and the surface of the metal material serves as a barrier against the invasion of corrosive substances, so that the corrosion resistance of the metal material is improved. However, with the recent improvement in quality of metal products, the coating itself is required to have high corrosion resistance, and a coating obtained by tannic acid alone or in combination with an inorganic component has insufficient corrosion resistance, Practical application is impossible.

As a treatment method for improving the corrosion resistance of a metal material, Patent Document 1 discloses that an aqueous solution containing water-dispersible silica, an alkyd resin and a trialkoxysilane compound is applied to a metal surface and dried to form a film. A method of forming is disclosed. Further, Patent Document 2 and the like disclose a method of imparting corrosion resistance to a metal material by using a water-soluble or water-dispersible polymer of a hydroxystyrene compound. However, none of the methods can form a coating capable of imparting high corrosion resistance as a substitute for the chromate coating on the surface of the zinc-based plated steel sheet.

[0006] In Patent Document 3, a first layer comprising a silane coupling agent component having a reactive functional group and a water-soluble polymer having a hydroxystyrene compound structure on the surface of a metal material, and a second layer thereon. Describes an organic composite coated metal material formed with a resin coating containing silica.
However, this surface treatment requires separate application and baking of the first layer and the second layer (2 coats and 2 bake) in order to secure sufficient corrosion resistance and top coatability. Becomes complicated. As described in this publication as the prior art, the water-soluble polymer used for the first layer cannot impart the excellent corrosion resistance comparable to that of chromate by itself, and therefore, the silica of the second layer cannot be obtained. A resin coating containing was required. In addition, the film containing resin is 2
Since a layer is also formed, there is a drawback that the weldability is significantly impaired.

[0007]

[Patent Document 1] Japanese Patent Laid-Open No. 53-121034

[Patent Document 2] JP-A-1-177380

[Patent Document 3] Japanese Patent Laid-Open No. 11-276987

[0008]

As described above, without using chromium, it is possible to impart corrosion resistance comparable to or exceeding that of a chromate film, excellent in weldability, and coatable on topcoat. At present, no surface treatment solution for zinc-based plated steel sheet that can form a good film has been developed.

An object of the present invention is to treat a zinc-based plated steel sheet with a chromium-free coating capable of exhibiting excellent performance (corrosion resistance, top coatability, weldability) that can substitute for a chromate coating. It is an object to provide a zinc-based plated steel sheet, a method for producing the same, and a treatment liquid therefor by an inexpensive means.

[0010]

[Means for Solving the Problems] The inventors of the present invention diligently studied the composition of the treatment liquid in order to form a film having a performance equal to or higher than that of a conventional chromate film with a treatment liquid containing no chromium. did. As a result, it was confirmed that such a film can be formed by using a specific resin. Further, in order to exert even more excellent performance, in addition to the resin, it has also been found that it is effective to use at least one of a titanium compound and a zirconium compound, if necessary, together with a silane coupling agent,
The present invention has been completed.

The present invention provides a water-soluble resin (a) comprising a polymer molecule having a repeating unit represented by the following general formula (1) and having an average degree of polymerization of 2 to 50, and at least one of a titanium compound and a zirconium compound ( b) and a chromium-free aqueous solution having a pH of 2.0 to 6.5 for treating the surface of a zinc-based plated steel sheet.

[0012]

[Chemical 3]

Where Y ₁ and Y ₂ are each independently
Hydrogen atom or Z represented by the following formula (2) or (3)
Means radical

[0014]

[Chemical 4]

R ₁ , R ₂ , R ₃ , R ₄ and R ₅ in formulas (2) and (3) are each independently a hydrogen atom, a C ₁ -C ₁₀ alkyl group or a C ₁ -C ₁₀ It represents a hydroxyalkyl group, and the average number of substitutions of the Z group per benzene ring in the polymer molecule is 0.2 to 1.0.

This treatment liquid contains at least one silane coupling agent (c) having at least one functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group and a methacryloxy group. It may further be contained in an amount of 10 to 90% by mass with respect to the total amount of a).

The total amount of titanium compound and zirconium compound (b) in the treatment liquid is 0.0010 per 1 kg of the treatment liquid.
It is preferable that the amount is not less than molar. From another side,
The present invention is a chromium-free zinc-plated steel sheet, characterized in that it has a dry film formed from the above-mentioned treatment liquid on the surface of the zinc-plated steel sheet. The amount of the dry film deposited is preferably in the range of 10 to 1000 mg / m ² .

From still another aspect, the present invention is a method for producing a non-chromium-treated zinc-based plated steel sheet, which comprises coating the surface of a zinc-based plated steel sheet with the above treatment liquid and then drying. Drying is preferably carried out at a temperature of 50 to 200 ° C. Here, the drying temperature means the ultimate plate temperature.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. In the present specification, “%” indicating the composition ratio is
Unless otherwise specified, it is “mass%”.

The treatment liquid according to the present invention is composed of a water-soluble resin (a) composed of a polymer molecule having a repeating unit represented by the following general formula (1). The water-soluble resin (a) is an oligomer or polymer having an average degree of polymerization (n) of 2 to 50.

[0021]

[Chemical 5]

In the formula, Y ₁ and Y ₂ which can be bonded to any position of the benzene ring each independently represent a hydrogen atom or a Z group represented by the following formula (2) or (3). .

[0023]

[Chemical 6]

R ₁ , R ₂ , R ₃ , R ₄ and R ₅ in formulas (2) and (3) are each independently a hydrogen atom, a C ₁ -C ₁₀ alkyl group or C ₁ to C _It represents ₁₀ hydroxyalkyl groups, and the average number of substitutions of the Z groups per benzene ring in the polymer molecule is 0.2 to 1.0.

The number of carbon atoms of the substituents R _{1 to} R ₅ present in the Z group is
When it is 11 or more, the film-forming property of the treatment liquid is deteriorated, so that the treated zinc-based plated steel sheet has insufficient corrosion resistance and top coatability. The carbon number of this substituent is preferably 1 to 6, more preferably 1 to 4, and particularly preferably 1 to 2.

The average number of substitutions of Z groups per benzene ring is 0.
If it is less than 2, the adhesion of the resin to the surface of the substrate will be insufficient, and the coatability will be poor. The average number of substitutions is 1.0
(Ie, more than one Z group is substituted on each benzene ring on average), the resin becomes too hydrophilic,
Corrosion resistance of the treated zinc-based plated steel sheet becomes insufficient. The average number of substitutions is preferably 0.3 to 0.7. Substituent is formula
In the case of the ionic ammonium group represented by (3), the average substitution number is preferably less than 0.5.

The above water-soluble resin is also disclosed in the above-mentioned Patent Document 3, but in this Patent Document, the resin is merely used as a material for forming the first layer film. Two-coat-two-bake forming a water-insoluble resin film containing silica on the first layer film ensures corrosion resistance and top coatability. Therefore, the corrosion resistance and the top coatability are insufficient only with the film containing the water-soluble resin.

On the other hand, in the present invention, a treatment liquid is prepared by adding at least one of a titanium compound and a zirconium compound, and preferably a silane coupling agent further containing a functional group, to the above water-soluble resin. Only the film formed from this treatment liquid (that is, one coat
One bake) can form a film with excellent corrosion resistance and coatability as a chromate film. The water-soluble resin becomes insoluble in water when dried.

Titanium compounds and zirconium compounds
(b) is mainly added to improve the corrosion resistance. Titanium compounds that can be used include, for example, water-soluble inorganic titanium compounds such as titanium sulfate, titanium oxysulfate, titanium hydrofluoric acid and ammonium titanium fluoride, organic acid titanium salts such as titanium potassium oxalate and titanium citrate, and titanium alkoxide. And so on. Further, a titanate coupling agent can also be used as the titanium compound. As the zirconium compound, zirconium sulfate,
Water-soluble inorganic zirconium compounds such as zirconium oxychloride, zirconium nitrate, zircon hydrofluoric acid and ammonium zircon fluoride, zirconium propionate, organic acid zirconium salts such as zirconium acetate, zirconium alkoxide, zirconate coupling agents, etc. Can be mentioned.

Titanium compounds and zirconium compounds
The total amount of (b) is preferably 0.0010 mol or more per 1 kg of the treatment liquid. If the total amount of the titanium compound and the zirconium compound (b) is less than 0.0010 mol, the effect of adding the titanium compound and the zirconium compound (b) will not be exhibited and the treated zinc-based plated steel sheet will have insufficient corrosion resistance. The upper limit of the total amount of the titanium compound and the zirconium compound (b) is not particularly limited, but the effect is saturated even if the amount is too large, and therefore it is usually preferably 0.1 mol or less per kg of the treatment liquid. The more preferable total amount of the titanium compound and the zirconium compound (b) is the treating liquid 1
It is 0.0050 to 0.050 mol per kg.

The treatment liquid according to the present invention may further contain a silane coupling agent (c) in order to further improve the corrosion resistance. The silane coupling agent (c) may be any one having at least one functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group and a methacryloxy group as a reactive functional group in one molecule. Well, the structure is not particularly limited, but the following compositions can be used as specific examples.

Those having an amino group: N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2
-Aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane; those having an epoxy group: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane; those having vinyl groups: vinyltriethoxysilane; those having mercapto groups: 3-mercaptopropyltrimethoxysilane; those having methacryloxy groups: 3-methacryloxypropyl Trimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane.

Silane coupling agent (c) used in the present invention
Is a mixture of at least one silane coupling agent having at least one active hydrogen-containing amino group or mercapto group (a) and at least one silane coupling agent having at least one epoxy group (a). Preferably there is. In that case,
The mixing ratio of the two types of silane coupling agents (a) and (a) is such that the equivalent ratio of the active hydrogen-containing amino group or mercap group contained in the silane coupling agent mixture to the epoxy group is 3: 1 to 1: 1. It is preferable to set it in the range of 3. When this equivalent ratio is outside the range of 3: 1 to 1: 3, the film-forming property of the treatment liquid may be poor and the treated zinc-based plated steel sheet may have insufficient corrosion resistance and top coatability.

When the silane coupling agent (c) is contained, the content of the silane coupling agent (c) is preferably 10% to 90% with respect to the total amount of the water-soluble resin (a). , And more preferably 20% to 50%. If the content of the silane coupling agent (c) is less than 10%, the adhesion of the coating to the substrate surface will be reduced, and corrosion resistance and paintability may be insufficient. On the other hand, if the content of the silane coupling agent (c) is more than 90%, the film forming property of the treatment liquid may be deteriorated, and the corrosion resistance and top coatability of the treated zinc-based plated steel sheet may be insufficient. .

The pH of the treatment liquid according to the present invention is 2.0 to 6.5. A treatment liquid having a pH of less than 2.0 has an excessively high reactivity with the surface of the substrate and causes a coating defect, resulting in insufficient corrosion resistance, paintability, workability and the like of the treated zinc-based plated steel sheet. When the pH of the treatment liquid exceeds 6.5, the water-soluble resin (a) itself tends to precipitate out of the treatment liquid, which shortens the life of the treatment liquid. The pH of the treatment solution is preferably 3.0 to 6.0, more preferably 3.5 to 5.5. The pH of the treatment liquid is
If necessary, it can be adjusted by adding a suitable acid or base. Phosphoric acid, acetic acid, nitric acid or the like is preferably used as the acid, and aqueous ammonia is preferably used as the base.

The treatment liquid is an aqueous solution in which the water-soluble resin (a) is dissolved in water, but a water-miscible organic solvent such as alcohol is used as a part of the solvent in an amount up to about 5% by mass of the solvent. It is possible to do so.

The zinc-based plated steel sheet surface-treated with the treatment liquid of the present invention may be any galvanized steel sheet or zinc alloy-plated steel sheet. Examples of the plating include hot-dip galvanizing, hot-dip Zn-5% Al or Zn-55% Al zinc alloy plating, hot-dip galvanizing, electrogalvanizing, and electric Zn.
-Ni alloy plating or the like can be used. The amount of plating applied is not particularly limited and is within the normal range (eg, 10 to 100 g / m ² ).
Good. If the upper layer is zinc-based plating, a double-layer plated steel sheet can also be used. When the zinc-based plated steel sheet is double-sided plated, it is preferable to treat both plated sides with the treatment liquid of the present invention, but it is also possible to treat only one side.

Before the surface treatment of the zinc-based plated steel sheet with the treatment liquid of the present invention, it is preferable to perform a suitable pretreatment known to those skilled in the art to clean the surface. For example, the surface of the zinc-based plated steel sheet can be degreased and washed with water as a pretreatment.

The treatment liquid can be applied by any suitable method such as a roll coater method, a spray method and a dipping method. The coating is preferably performed at a temperature of about 0 to 50 ° C.
Dry after application. Water-soluble resin used in the present invention (a)
Can form a film only by drying (ie, evaporation of water).
In order to dry in a short time, it is preferable to carry out the drying at a temperature of 50 to 200 ° C. (achieved plate temperature). The preferred drying temperature is 100 ° C., which is the boiling point of water.

Thus, the coating film containing the resin (a) and at least one of the titanium compound and the zirconium compound (b) and optionally the silane coupling agent (c) covers the surface of the zinc-based plated steel sheet. Is formed as. The titanium compound and the zirconium compound (b) contribute to improving the corrosion resistance of the film. The further presence of the silane coupling agent further improves the corrosion resistance.

As described above, one of the titanium compound and the zirconium compound may be added, or both may be used in combination. Comparing the two, the effects on the corrosion resistance are almost the same, but when the titanium compound is used, the formed film becomes slightly yellowish.
When a colorless film is required, it is desirable to use only the zirconium compound or to increase the ratio of the zirconium compound to the titanium compound as much as possible.

The amount of the dry film formed from the treatment liquid of the present invention is not particularly limited, but preferably 10 to 1000 mg /
It is in the range of m ² , more preferably 20 to 200 mg / m ² . This coating is capable of imparting superior corrosion resistance to or exceeding that of conventional chromate coatings to the base metal, and also has sufficient top coatability and weldability, but compared to conventional non-rom coatings. Is cheap.

The non-chromium-treated zinc-based plated steel sheet obtained by forming a coating on the zinc-based plated steel sheet by applying the treatment liquid of the present invention and drying shows corrosion resistance equal to or higher than that of the chromate-treated zinc-based plated steel sheet, and is welded. Since the property is also good,
It can be assembled by spot welding. This steel sheet also has a good top coatability, and can be coated before or after forming / assembling, whereby a coating film having good adhesion can be obtained.

[0044]

EXAMPLES The working effects of the present invention will be specifically illustrated by using Examples and Comparative Examples. These examples are provided by way of illustration of the invention and are not intended to limit the invention in any way.

[0045]

Example 1 This example illustrates the case where a zinc-based plated steel sheet is directly surface-treated with the treatment liquid of the present invention.

[Preparation of Test Surface Treated Steel Sheet] (1) Test Material Commercially available double-sided zinc-based plated steel sheet shown below was used as a test material. The size of the test material is 200 x 300 mm: Electrogalvanized steel sheet (EG), thickness 0.8 mm, basis weight = 20/2
0 (g / m ² ) hot-dip galvanized steel sheet (GI), thickness 0.8 mm, basis weight = 60/6
0 (g / m ² ).

(2) Surface treatment Each test material of the above zinc-based plated steel sheet was treated with a solution of Fine Cleaner 4336 (registered trademark: manufactured by Nihon Parkerizing Co., Ltd.), a silicate-based red degreasing agent, at a concentration of 20 g / l. 60 ° C
It was degreased by spraying for 2 minutes, washed with tap water, and pretreated.

On one surface of the pretreated test material, the treatment liquid having the content shown in Table 1 was applied by bar coating at room temperature and dried in an oven for 30 seconds to form a dry film. The adhesion amount of the film was adjusted by the gap of the bar coater. The actual coating amount was measured by a gravimetric method. Of Table 1
The treatment liquid of No. 8 is a treatment liquid containing no resin and containing only the same type and amount of the titanium compound (b) and the silane coupling agent (c) as those of No. 6. Treatment liquid N in Table 1
o.4 to 7 are processing solutions according to the present invention, and the rest are processing solutions for comparison.

Table 2 collectively shows the types of base materials and treatment liquids used, the amount of coating adhered, and the drying temperature (achieved plate temperature). The surface-treated zinc-based plated steel sheet thus obtained was evaluated for corrosion resistance, weldability, and topcoat adhesion by the following methods. As for the evaluation criteria of the test, the acceptable level is "○" in any test. The test results are also shown in Table 2. for reference,
The results when a standard reactive chromate film is applied are also shown.

[Treatment plate performance test] (1) Corrosion resistance After tape-sealing the back and end faces of a sample cut to 70 x 150 mm, the surface coated with the above-mentioned treatment liquid was JIS-
A salt spray test with Z-2371 was performed for 96 hours, the occurrence of white rust was observed, and the evaluation was performed according to the following criteria.

<Evaluation criteria> ◎: Area where self-rust occurs is 0% of the total area, ○: less than 5% of the total self-rusting area, Δ: Self-rusting area is 5% or more and less than 20% of the total area, X: The self-rusting area is 20% or more of the total area.

(2) Weldability Using a center flat type electrode (Cu-Cr) with a tip diameter of 3.5 mm, welding current value 7 kA, energizing time 12 cycles, pressure 15
A continuous spot weldability test was carried out at 0 kgf, and the number of continuous spots until the nugget diameter fell below the standard diameter was evaluated according to the following criteria.

<Evaluation criteria> Reference diameter: 5 √t (t: plate thickness) = 4.47 mm ◎: 1000 points or more ○: More than 600 and less than 1000 △: 300 points or more and less than 600 points ×: Less than 300 dots

(3) Topcoat coatability A melamine alkyd paint (registered trademark: Glymin, manufactured by Shinto Paint Co., Ltd.) is baked on the surface of the sample on which the above-mentioned treatment liquid is applied, and the film thickness after drying becomes 25 μm. And then baked at 120 ° C. for 30 minutes. After baking, it was immersed in warm water at 80 ° C. for 2 hours. Then, using a test piece that had been left for 24 hours, 100 grids at 1 mm intervals were drawn, and then the coating film was peeled off with Cellotape (registered trademark), and evaluation was performed according to the following criteria.

<Evaluation criteria> ◎: No peeling of coating film, 100% remaining coating film, ○: 90% or more of the remaining coating film, Δ: 50% or more and less than 90% of the remaining coating film, X: The number of remaining coating films is less than 50%.

[0056]

[Table 1]

[0057]

[Table 2]

Examples 1 to 11 using the surface treatment liquid of the present invention
, The corrosion resistance, weldability, and top coatability are all good, and the performance is equal to or higher than that of the chromate film. In particular, the corrosion resistance and top coatability are superior to those of chromate. On the other hand, in Comparative Examples 1 to 7 using surface treatment liquids outside the scope of the present invention, all of corrosion resistance, weldability, and top coatability cannot be satisfied.

(4) Example 1 in which the surface tone-formed coating contains a titanium compound,
For the two types of surface-treated plated steel sheets of Example 7 containing a zirconium compound, the b * value of JIS Z8729, which is an index of yellowness, was measured in order to examine the surface color tone of the test piece.
The results are shown in Table 3.

[0060]

[Table 3]

As shown in Table 3, the coating of Example 1 containing the titanium compound has a yellowish tint. However, even the film of Example 1 is not so yellowish. It is difficult to judge the difference in surface color tone between the test pieces of Example 1 and Example 7 when visually observed, and it is observed that the film of Example 1 is slightly yellowish when observed side by side. It is recognizable.

[0062]

As described above, by coating the zinc-based plated steel sheet with the chromium-free treatment liquid of the present invention and drying it, it is possible to obtain chromium containing excellent corrosion resistance, weldability, and top coatability. It is possible to obtain a non-chromium-treated zinc-based plated steel sheet. INDUSTRIAL APPLICABILITY The present invention is extremely effective as a countermeasure for social problems such as environmental protection and recyclability and has a great practical effect.

Claims (7)

[Claims] 1. A water-soluble resin (a) comprising a polymer molecule having an average degree of polymerization of 2 to 50 and having a repeating unit represented by the following general formula (1), and at least one of a titanium compound and a zirconium compound (b). Contains and does not contain chromium, pH
A treatment solution for surface treatment of zinc-based plated steel sheet, which is an aqueous solution of 2.0 to 6.5. [Chemical 1] In the formula, Y ₁ and Y ₂ each independently represent a hydrogen atom or a Z group represented by the following formula (2) or (3): R ₁ , R ₂ , R ₃ , R ₄ and R ₅ in formulas (2) and (3) are each independently a hydrogen atom, a C _{1 to} C ₁₀ alkyl group or C ₁
To C ₁₀ hydroxyalkyl group, and the average number of substitutions of the Z group per benzene ring in the polymer molecule is 0.2 to 1.0. 2. One or more silane coupling agents (c) having at least one functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group and a methacryloxy group, and (a) 10 to 90 for the total amount of
The processing liquid according to claim 1, further comprising a mass% amount. 3. Titanium compound and zirconium compound
The treatment liquid according to claim 1 or 2, wherein the total amount of (b) is 0.0010 mol or more per kg of the treatment liquid. 4. The surface of the zinc-based plated steel sheet is coated with
A non-chromium-treated zinc-based plated steel sheet having a dry film formed from the treatment liquid according to any one of 3 above. 5. The adhesion amount of the dry film is 10 to 1000 mg / m ²
The non-chromium-treated zinc-based plated steel sheet according to claim 4 or 5, which is within the range. 6. The surface of a zinc-based plated steel sheet is coated with
3. A method for producing a non-chromium-treated zinc-based plated steel sheet, which comprises applying the treatment liquid according to any one of 3 and then drying. 7. The method according to claim 6, wherein the drying is carried out at a temperature of 50 to 200 ° C.