KR20180015133A - Surface treated steel plate - Google Patents

Abstract

This surface-treated steel sheet comprises a steel sheet and a plating layer formed on one or both surfaces of the steel sheet and including zinc and vanadium or zirconium, the plating layer comprising a dendritic phase crystal containing metal zinc, Wherein said intercalated region has an intergranular filling region exhibiting an amorphous diffraction pattern when said upper intergranular phase is filled with said intergranular phase and said intergranular phase is filled with said vanadium oxide or vanadium Hydroxide, and in the case where the plating layer includes zirconium, the intercrystalline fill region includes hydrated zirconium oxide or zirconium hydroxide.

Description

Surface treated steel plate

The present invention relates to a surface-treated steel sheet excellent in corrosion resistance (barrier property) and coating film adhesion in a corrosive environment.

The present application claims priority based on Japanese Patent Application No. 2015-116554 and Japanese Patent Application No. 2015-116604 filed on June 9, 2015, the contents of which are incorporated herein by reference.

BACKGROUND ART [0002] Electro galvanized steel sheets have been conventionally used in various fields such as household appliances, building materials, and automobiles. In electrogalvanized steel sheets, it is required to further improve corrosion resistance (hereinafter, barrier property) of plating in a corrosive environment.

As a method of improving the barrier property of the electrodiald zinc plated steel sheet, it is conceivable to increase the plating amount (coating amount) of the zinc plated layer. However, when the coating amount of the zinc plating layer is increased, there is a problem that the manufacturing cost is increased and the workability and weldability are lowered.

Further, as a method for improving the barrier property and appearance of an electrogalvanized steel sheet, a technique of forming a coating film on the surface has been widely used. However, if the coating layer of the electro-galvanized steel sheet and the coating film have poor adhesion (coating film adhesion), even if a coating film is formed on the surface, the effect of forming a coating film is not sufficiently obtained. For this reason, it is demanded to improve the barrier property of the electro-galvanized steel sheet and to improve the coating film adhesion.

Recently, it has been studied to improve the barrier property by containing a vanadium element in a galvanized layer of an electro-galvanized steel sheet. For example, in Non-Patent Documents 1 to 4, a technique of compounding a Zn-V oxide on the surface of a copper plate serving as a negative electrode is described.

Patent Document 1 discloses a technique of forming a V-enriched layer on the surface layer portion of a plated layer of a zinc plated steel sheet.

Patent Document 2 discloses a technique relating to a plating layer containing zinc and vanadium and having a plurality of dendrite-shaped arms.

Patent Document 3 discloses that a plating layer containing zinc and vanadium formed on a steel sheet has a dendritic phase crystal in which vanadium oxide is present in zinc and a dendrite phase crystal It is described that a phase having a higher content of vanadium is present than in the presence of the catalyst.

Patent Document 4 discloses that a zinc-based composite electroplated steel sheet containing zinc and vanadium hydroxide has vacancy of vanadium hydroxide in zinc.

Japanese Patent Application Laid-Open No. 2013-185199 Japanese Patent No. 5273316 Japanese Patent Application Laid-Open No. 2013-108183 Japanese Patent Laid-Open No. 1111633

CAMP-ISIJ Vol.22 (2009) -933-936 Iron and Steel Vol.93 (2007) No.11, pages 49-54 Surface Technology Association 115th Lecture Meeting Collection, 9A-26, pp. 139-140 Perum Vol.13, No. 4, 245 pages, April 4, 2008

However, in the conventional surface-treated steel sheet having a plating layer containing zinc and vanadium on the surface of the steel sheet, it is required to further improve the barrier property.

In addition, since V (vanadium) is a rare element, plating that is superior in barrier property in place of zinc vanadium plating is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a surface-treated steel sheet excellent in barrier property and coating film adhesion, in which a plating layer containing zinc and vanadium or zirconium is formed on the surface of a steel sheet.

Means for Solving the Problems In order to solve the above-described problems, the inventor of the present invention has conducted intensive studies as described below.

That is to say, the inventors of the present invention investigated the barrier property and the coating film adhesion by forming a plating layer containing zinc and vanadium or zirconium on the surface of a steel sheet under various conditions using a steel sheet as a negative electrode by an electroplating method.

As a result, the present inventors have found that a plating layer containing zinc and vanadium, which is a plating layer having a interdigitally charged region containing hydrated vanadium oxide or vanadium hydroxide, and a dendritic phase crystal containing zinc metal can be formed I got it. Such a plating layer has an intercrystalline filled region containing hydrated vanadium oxide or vanadium hydroxide. Therefore, the corrosion potential is nobler than that of a plated steel sheet formed by forming a zinc plated layer instead of the plated layer, for example, It is also excellent in barrier property.

Further, the present inventor has found that under certain conditions, an image containing hydrated zirconia oxide or zirconia hydroxide is formed around the dendritic phase crystal made of metal zinc. It has been found that such a plated layer has barrier properties equal to or greater than those of zinc vanadium plating and has excellent coating film adhesion, and thus the present invention has been accomplished. Each mode of the present invention is as follows.

(1) A surface-treated steel sheet according to one aspect of the present invention comprises a steel sheet, and a plating layer formed on one or both surfaces of the steel sheet, the plating layer including zinc and vanadium or zirconium, Wherein the interlayer insulating film has a dendrite phase crystal and an intercrystalline region filled with the dendrite phase crystal and exhibiting an amorphous diffraction pattern when electron beam diffraction is performed and the plating layer contains vanadium, Wherein the region comprises hydrated vanadium oxide or vanadium hydroxide and the intercalary charge region comprises hydrated zirconium oxide or zirconium hydroxide when the plating layer comprises zirconium.

(2) In the surface-treated steel sheet according to (1), when the plating layer contains vanadium, V / Zn, which is a molar ratio of vanadium and zinc in the inter-crystal charged region, is 0.10 or more and 2.00 or less, In the case where the plating layer contains the zirconium, a composition in which Zr / Zn, which is the molar ratio of zirconium to zinc in the intercritical fill region, is 1.00 or more and 3.00 or less may be adopted.

(3) In the surface-treated steel sheet according to (1) or (2), when the plating layer contains vanadium and the surface layer of the dendritic phase crystal contains zinc oxide or zinc hydroxide do.

(4) The surface-treated steel sheet according to any one of (1) to (3), further comprising a lower plating layer between the steel sheet and the plating layer having a Zn / V ratio of 8.00 or more as a molar ratio of zinc and vanadium Configuration may be employed.

(5) The surface-treated steel sheet according to any one of (1) to (4), further comprising an organic resin film having a polyurethane resin and 1 to 20 mass% carbon black on the surface of the plating layer Configuration may be employed.

6, the manufacturing method of the surface-treated steel sheet according to one embodiment of the present invention is a method for producing a surface-treated steel sheet according to any one of (1) to (5), 0.10 and Zn ² of 4.00mol / l ^By carrying out electroplating at a current density of 0 to 18 A / dm 2 using a plating bath containing a ^positive ion, a ^positive ion, a negative ion of 0.01 to 2.00 mol / l or a Zr ion of 0.10 to 4.00 mol / l, A step of forming irregularities by precipitating hydrated vanadium oxide or vanadium hydroxide on the surface of the steel sheet on which the concavities and convexities have been formed by using the plating bath and electroplating at a current density of 21 to 200 A / Is carried out.

According to each of the above-mentioned aspects, it is possible to provide a surface-treated steel sheet having excellent barrier properties and coating film adhesion.

1 is a schematic cross-sectional view for explaining an example of a surface-treated steel sheet according to the first embodiment.
2 is a schematic cross-sectional view for explaining an example of a surface-treated steel sheet according to the second embodiment.
3 is a schematic view showing an example of a plating apparatus used in producing a surface-treated steel sheet according to the present embodiment.
4A is a schematic view for explaining deposition of a vanadium compound in the step of producing the surface-treated steel sheet shown in Fig.
Fig. 4B is a schematic view for explaining the growth of the dendritic phase crystal in the step of producing the surface-treated steel sheet shown in Fig.
Fig. 4C is a schematic diagram for explaining the generation of hydrogen at the tip of the branch of the dendritic phase crystal in the step of producing the surface-treated steel sheet shown in Fig.
5A is a cross-sectional photograph of the entire surface of the surface-treated steel sheet of Example V4 in the thickness direction by a transmission electron microscope (TEM) of a plating layer.
Fig. 5B is an enlarged photograph of the interface between the steel sheet and the plating layer in the section of Fig. 5A. Fig.
5C is an enlarged photograph of the dendritic phase crystal and its peripheral portion in the section of FIG. 5A.
6 is a scanning electron microscope (SEM) photograph of the plating layer of the surface-treated steel sheet of Example V4.
7 is a scanning electron microscope (SEM) photograph of the plating layer of the surface-treated steel sheet of Comparative Example x2.
8 is a photograph showing the electron beam diffraction image of the plating layer of the surface-treated steel sheet of Example V4.
9 is a transmission electron microscope (TEM) photograph of the plating layer of the surface-treated steel sheet of Example Z4.

&Quot; First embodiment, surface-treated steel sheet (10) "

Hereinafter, the surface treated steel sheet 10 of the first embodiment in the case where the plating layer contains vanadium will be described in detail with reference to the drawings.

1 is a schematic cross-sectional view for explaining an example of a surface-treated steel sheet 10 according to the present embodiment. The surface-treated steel sheet 10 shown in Fig. 1 has a base layer 20, a plated layer 30 and a surface layer 40 formed on both surfaces of the steel sheet 1 in this order from the steel sheet 1 side. 1, only the foundation layer 20, the plating layer 30 and the surface layer 40 formed on one surface (upper surface) side of the steel sheet 1 are described and only the surface layer .

In the present embodiment, the steel sheet 1 on which the plating layer 30 is formed is not particularly limited. For example, it is possible to use, as the steel sheet 1, an extremely low C type (ferrite based structure), an Al-k type (a structure containing pearlite in ferrite), a two phase structure type (e.g., a structure including martensite in ferrite , A structure containing bainite in ferrite), a processed organic transformation type (a structure containing retained austenite in ferrite), and a microcrystalline type (ferrite based structure).

As shown in Fig. 1, a ground layer 20 may be formed between the steel sheet 1 and the plated layer 30. Fig. The base layer 20 is formed as necessary in order to improve the adhesion between the steel sheet 1 and the plating layer 30. In the present embodiment, it is preferable that the ground layer 20 having a thickness of 1 to 300 nm and made of a crystal containing nickel is formed.

The plating layer 30 is disposed between the dendritic phase crystal 31 and the dendritic phase crystal 31 as shown in Fig. 1 and has an amorphous diffraction pattern in the case of electron beam diffraction, (Not shown).

In the present invention, "amorphous" means that a diffraction pattern due to the crystal structure is not obtained by performing electron beam diffraction for each layer from the cross-sectional direction using a transmission electron microscope (TEM).

The intercrystalline fill region 32 comprises hydrated vanadium oxide or vanadium hydroxide. The inter-crystalline charged region 32 preferably contains vanadium hydroxide in order to improve the film adhesion.

Further, the inter-crystalline charged region 32 preferably contains zinc. The intercrystalline filling region 32 contains zinc, thereby improving the corrosion resistance.

It is preferable that the molar ratio (V / Zn) of vanadium and zinc in inter-crystal charged region 32 is not less than 0.10 and not more than 2.00 when intercalated charge region 32 includes hydrated vanadium oxide or vanadium hydroxide and zinc. When the above-mentioned mole ratio (V / Zn) is in the above range and the intergranular filling region exhibits an amorphous diffraction pattern when electron beam diffraction is performed, excellent corrosion resistance (barrier property) and coating film adhesion can be obtained. When the molar ratio (V / Zn) of vanadium and zinc in the inter-crystalline charged region 32 is less than 0.10, an amorphous diffraction pattern may not be stably obtained, and corrosion resistance is deteriorated. On the other hand, if the molar ratio exceeds 2.00, the sacrificial corrosion resistance of the plating deteriorates.

As shown in FIG. 1, a plurality of dendritic phase crystals 31 are formed in the plating layer 30. The shapes of the plurality of dendritic phase crystals 31 may be all different or may include the same. The shape of each dendritic phase crystal 31 may be a needle shape or a rod shape. Each of the dendritic phase crystals 31 may extend linearly in the longitudinal direction or may extend in a curved shape. The sectional shape of each dendritic phase crystal 31 is not particularly limited, and examples thereof include a circle, an ellipse, and a polygon. The cross-sectional shape of each dendritic phase crystal 31 may be uniform in the longitudinal direction or may be non-uniform. In addition, the outer dimension of each dendritic phase crystal 31 may be uniform in the longitudinal direction or may be non-uniform.

In the surface treated steel sheet 10 of the present embodiment, each dendritic phase crystal 31 is divided into a dendrite phase crystal interior 3a and a dendrite phase crystal 31 surface And a surface layer 3b formed thereon. The inside 3a of the dendritic phase crystal 31 is grown toward the outside from the side of the steel plate 1 and has a plurality of branched branches. The surface layer 3b is formed to have a substantially uniform thickness so as to cover the surface of the inside 3a of the dendritic phase crystal 31. [

The dendritic phase crystal 31 shown in Fig. 1 having the inside 3a and the surface layer 3b of the dendritic phase crystal 31 has a maximum length of 4.0 占 퐉 or less and a maximum width when viewed in cross section of 0.5 占 퐉 Or less. When the maximum length and the maximum width of the dendritic phase crystal 31 are in the above range, a dense plated layer 30 having fine dendrite phase crystals 31 is obtained. Therefore, the barrier function of the plating layer 30 is improved, and more excellent barrier property can be obtained. In order to further improve the barrier property, the maximum length of the dendritic phase crystal 31 is more preferably 3.0 m or less. Further, it is more preferable that the maximum width of the dendritic phase crystal 31 viewed from the end face is 0.4 탆 or less.

In the present embodiment, the "maximum length of the dendritic phase crystal 31" refers to the maximum length of 50 dendritic phase crystals 31 measured by scanning electron microscope (SEM) , And calculating the average value thereof.

The "maximum width in the cross section of the dendritic phase crystal 31" refers to the maximum width of the 50 dendritic phase crystals 31 measured by using a transmission electron microscope (TEM) , And calculating the average value thereof.

The inside 3a of the dendritic phase crystal 31 preferably contains metal zinc. The inside 3a of the dendritic phase crystal 31 may contain other metal components such as nickel, which is more attractive than zinc precipitation potential, in addition to metal zinc.

Further, the surface layer 3b preferably contains a crystal containing zinc oxide or zinc hydroxide. More preferably, the surface layer 3b contains crystals of zinc oxide. The thickness of the surface layer 3b is preferably 0.1 to 500 nm.

1, the granular crystals 3c may be included in the interior 3a of the dendritic phase crystal 31. In this case, The granular crystals 3c include zinc and nickel. The grain size of the granular crystals 3c is preferably 0.1 to 500 nm. When the particle diameter of the granular crystals 3c is within the above range, more excellent film adhesion can be obtained.

In the surface treated steel sheet 10 of the present embodiment, it is preferable that Zn / V, which is the molar ratio of zinc and vanadium contained in the plating layer 30, is 0.50 or more and less than 8.00. When Zn / V is 0.50 or more and less than 8.00, it is preferable because an excellent barrier function by containing vanadium is obtained.

In the surface treated steel sheet 10, between the steel sheet 1 and the plated layer 30 (between the base layer 20 and the plated layer 30 when the ground layer 20 is formed) A plating layer (not shown) may be formed. This is because the base plating layer (not shown) is formed, whereby an excellent corrosion resistance improving effect by the zinc sacrifice method can be obtained.

The base plating layer (not shown) contains zinc and vanadium, and Zn / V, which is the molar ratio of the zinc to the vanadium, may be 8.00 or more. Further, the base plating layer (not shown) may be made of only zinc.

An upper layer plating layer (not shown) containing zinc may be formed on the upper layer of the plating layer 30. [ Since an upper layer plating layer (not shown) is formed, an excellent corrosion resistance improving effect by the zinc sacrificial method can be obtained, which is preferable.

The upper layer plating layer (not shown) may be composed of only zinc. The upper layer plating layer (not shown) contains zinc and vanadium, and Zn / V, which is the molar ratio of the zinc to the vanadium, may be 8.00 or more.

When the underlayer 20 is formed between the steel sheet 1 and the plating layer 30 by controlling the current density of the electroplating and controlling the molar ratio of zinc and vanadium, the underlayer 20 and the plating layer 30 ), A base plating layer (not shown) can be formed.

An upper layer plating layer (not shown) can be formed on the plating layer 30 by the same method as that of the lower plating layer (not shown).

The sum of the amount of zinc contained in the inside 3a of the dendritic phase crystal 31 and the amount of zinc contained in the surface layer 3b of the intercalciferous charging region 32 and the dendritic phase crystal 31 b) is preferably in the range of 0.10 or more and 3.00 or less.

When the above-mentioned molar ratio (a / b) is 0.10 or more, when the surface of the plating layer 30 is scratched, a sacrificial action by the metal zinc contained in the dendritic phase crystal 31 is effectively obtained, Excellent barrier properties can be obtained. In order to more effectively obtain the action of the metal zinc contained in the dendritic phase crystal 31 by the sacrificial mode, it is more preferable that the molar ratio (a / b) is 0.20 or more.

When the molar ratio (a / b) is not more than 3.00, the zinc oxide or zinc hydroxide contained in the surface layer of the dendritic phase crystal 31 is hardly permeable to air or water. An improvement action can be effectively obtained, and more excellent barrier property can be obtained. In order to more effectively obtain the barrier property improving action by the surface layer 3b of the dendritic phase crystal 31, the above-mentioned molar ratio (a / b) is more preferably 0.25 or less.

The total amount A of the amount of zinc contained in the dendritic phase crystal 31 and the amount of zinc contained in the surface layer 3b of the dendritic phase crystal 31 and the total amount A of the vanadium And the molar ratio (A / B) of the amount (B) is preferably 0.05 or more and 6.00 or less. When the molar ratio (A / B) is 0.05 or more, the zinc oxide contained in the surface layer 3b of the dendritic phase crystal 31 and the zinc oxide contained in the dendritic phase crystal 31 The effect of improving the barrier property by the zinc hydroxide can be obtained effectively, and more excellent barrier property can be obtained.

The molar ratio (A / B) is preferably not less than 0.10 in order to more effectively achieve the sacrificial mode action by the dendritic phase crystal 31 and the barrier property improving effect by the surface layer 3b of the dendritic phase crystal 31 desirable. When the above-mentioned molar ratio (A / B) is 6.00 or less, the effect of improving corrosion resistance by containing vanadium is improved more effectively. The molar ratio (A / B) is more preferably 5.00 or less, and further preferably 4.50 or less in order to further improve the barrier property improving effect by the vanadium-containing substance.

In the present embodiment, the content of vanadium contained in the plating layer 30 is preferably 1% by mass to 20% by mass. When the amount of vanadium in the plating layer 30 is 1% by mass or more, more excellent barrier property is obtained. The vanadium content in the plating layer 30 is more preferably 4% by mass or more in order to further improve the barrier properties and the film adhesion. When the vanadium content in the plating layer 30 is 20 mass% or less, the content of the surface layer 3b of the dendritic phase crystal 31 and the surface layer 3b of the dendritic phase crystal 31 becomes relatively large, And the effect of improving the barrier property by the surface layer 3b of the dendritic phase crystal 31 can be effectively obtained.

The vanadium content of the plating layer 30 is more preferably 15 mass% or less in order to ensure the content of the dendritic phase crystal 31 and the surface layer 3b of the dendrite crystal 31.

The adhesion amount of the plating layer 30 is preferably 1 g / m 2 or more and preferably 3 g / m 2 or more in order to improve the barrier property. The amount of the plating layer 30 to be adhered is preferably 90 g / m 2 or less, more preferably 50 g / m 2 or less, and further preferably 15 g / m 2 or less. When the deposition amount of the plating layer 30 is 15 g / m 2 or less, the metal amount to be precipitated is smaller than that of the conventional electroplated zinc (usually about 20 g / m 2) or the like, Which is economically superior.

It is preferable that the surface-treated steel sheet 10 of this embodiment has a natural immersion potential (corrosion potential) of -0.8 V or higher when immersed in a 5% aqueous solution of NaCl at 25 캜 using the plating layer 30 as a working electrode. It is preferable that the above corrosion potential is 0.2 V or higher (attribution) higher than the plated steel sheet (corrosion potential -1.0 V or so) formed by forming the zinc plating layer in place of the plating layer 30. In order to further improve the barrier property, it is more preferable that the corrosion potential is -0.7 V or more.

As shown in Fig. 1, on the surface of the plating layer 30, a surface layer 40 composed of one or more coating films is formed. The surface layer 40 is formed as required. Since the surface layer 40 is formed, the corrosion resistance is improved.

It is preferable that the one or more layers forming the surface layer 40 contain an organic resin (R).

The organic resin (R) contained in the coating film is not particularly limited and, for example, a polyurethane resin can be mentioned.

The organic resin (R) contained in the coating film may be a mixture of one or more organic resins (unmodified ones), or may be used in combination with at least one other organic One or more organic resins obtained by modifying the resin may be used in combination.

Examples of the polyurethane resin to be used for the organic resin (R) include those obtained by reacting a polyol compound with a polyisocyanate compound and then subjecting the resultant mixture to a chain extender.

The polyol compound used as a raw material for the polyurethane resin is not particularly limited as long as it is a compound containing two or more hydroxyl groups per molecule, and examples thereof include ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol , Polyether polyols such as neopentyl glycol, triethylene glycol, glycerin, trimethylol ethane, trimethylol propane, polycarbonate polyol, polyester polyol and bisphenol hydroxypropyl ether, polyester amide polyol, acryl polyol, Polyol, or a mixture thereof.

As the polyisocyanate compound used as a raw material of the polyurethane resin, a compound containing at least two isocyanate groups per molecule is used, and examples thereof include aliphatic isocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) Alicyclic diisocyanates such as tolylene diisocyanate (TDI), aromatic aliphatic diisocyanates such as diphenylmethane diisocyanate (MDI), and mixtures thereof.

As the above-described chain extender used for producing the polyurethane resin, a compound containing at least one active hydrogen in the molecule is used, and examples thereof include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, , Aliphatic polyamines such as triethylenetetramine and tetraethylenepentamine, aromatic polyamines such as tolylene diamine, xylylenediamine and diaminodiphenylmethane, diaminocyclohexylmethane, piperazine, 2,5-dimethyl Alicyclic polyamines such as isophoronediamine and piperazine, hydrazines such as hydrazine, succinic acid dihydrazide, adipic acid dihydrazide and phthalic acid dihydrazide, and hydroxyethyldiethylenetriamine, 2 - [(2- Ethyl) amino] ethanol, 3-aminopropanediol, and other alkanolamines. These compounds used as chain extenders can be used alone or in combination of two or more.

The polyurethane resin used for the organic resin (R) can be obtained by heating the raw solution containing the block isocyanate compound and the polyol compound to a temperature at which the block agent is dissociated, and recovering the isocyanate group and the polyol compound May be obtained by reacting the components.

The block isocyanate compound regenerates the isocyanate group by heating to a temperature above the temperature at which the block agent dissociates. As the block isocyanate compound, for example, an isocyanate group of the polyisocyanate compound masked with a conventionally known block agent can be used. As the blocking agent, for example, dimethyl pyrazole (DMP), methyl ethyl ketone oxime and the like can be used.

The one or more layers of the coating film forming the surface layer 40 are formed by coating the phosphoric acid compound (P), the organic silicon compound (W), the carbon black (C), the fluoromethyl complex compound (F) , And a polyethylene wax (Q).

More preferably, the phosphoric acid compound (P) contained in the coating film is a phosphoric acid ion-releasing compound. When the phosphoric acid compound (P) is a compound (P) that releases phosphoric acid ions into the coating film, when the coating composition for forming the coating film is in contact with the plating layer (30) The phosphoric acid compound P reacts with the vanadium oxide existing on the surface of the plating layer 30 to form an insoluble phosphoric acid-vanadium-based coating film on the surface of the plating layer 30. Thus, the whitening resistance can be greatly improved.

When the phosphate compound (P) is not decomposable in the environment and does not emit phosphate ions, the phosphate compound (P) contained in the film inhibits the movement of corrosive factors such as water and oxygen, Loses.

As the phosphoric acid compound (P) contained in the film, for example, phosphoric acid such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid and the like or dihydrogen phosphate ammonium can be used. These phosphoric acid compounds (P) may be used alone or in combination of two or more.

The content of the phosphoric acid compound (P) contained in the film is preferably 1 to 20 mass%, more preferably 6 to 18 mass%, and most preferably 10 to 15 mass% as phosphate ions. When the concentration of phosphate ions contained in the film is 1% by mass or more, excellent barrier properties can be obtained. When the phosphoric acid ion concentration in the coating is 20 mass% or less, expansion of the coating film due to elution of phosphoric acid can be prevented.

When the phosphoric acid compound (P) is contained in the coating film, excellent barrier property to vanadium in the plating layer (30) and corrosion factor (water, oxygen, etc.) (Not shown) is formed. As a result, as compared with the case where the surface layer 40 is not formed on the surface of the plating layer 30, the effect of retarding the generation of red rust as well as the whitening resistance can be obtained, and the barrier property is remarkably improved.

As the organic silicon compound (W) contained in the coating film, for example, a hydrolysis-condensation product of a silane coupling agent can be exemplified.

Examples of the silane coupling agent used for forming the organic silicon compound (W) in the coating film include 3-glycidoxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane. The silane coupling agent may be used singly or in combination of two or more kinds.

It is preferable that the organosilicon compound (W) in the coating film is obtained by a reaction between a silane coupling agent (W1) containing an amino group and a silane coupling agent (W2) containing an epoxy group. In this case, a dense film having a high crosslinking density is formed by the reaction between the amino group and the epoxy group and the reaction between the alkoxysilyl groups or the partial hydrolysis products thereof contained in each of the silane coupling agent (W1) and the silane coupling agent (W2) do. As a result, the barrier properties, scratch resistance and stain resistance of the surface treated steel sheet are further improved.

As the silane coupling agent (W1) containing an amino group, for example, 3-aminopropyltriethoxysilane can be mentioned. As the silane coupling agent (W2) containing an epoxy group, for example, 3-glycidoxypropyltrimethoxysilane can be mentioned.

The molar ratio [(W1) / (W2)] of the silane coupling agent (W1) containing an amino group and the silane coupling agent (W2) containing an epoxy group is preferably 0.5 or more and 2.5 or less, more preferably 0.7 or more and 1.6 or less to be. When the molar ratio [(W1) / (W2)] is 0.5 or more, sufficient film formability is obtained, and barrier property is improved. When the above-mentioned molar ratio is 2.5 or less, sufficient water resistance can be obtained and excellent barrier properties can be obtained.

The organosilicon compound (W) contained in the film preferably has a number average molecular weight of, for example, 1000 or more and 10,000 or less, more preferably 2,000 or more and 10,000 or less. When the number-average molecular weight of the organosilicon compound (W) is 1000 or more, a coating film having excellent water resistance is obtained, and alkali resistance and barrier property are further improved. On the other hand, when the number average molecular weight of the organosilicon compound (W) is 10,000 or less, the organosilicon compound (W) can be stably dissolved or dispersed in an aqueous medium containing water as a main component, and storage stability may be lowered.

As a method of measuring the number average molecular weight of the organosilicon compound (W), a direct measurement by a time-of-flight mass spectrometry (TOF-MS) method may be used or a conversion measurement by a chromatography method may be used .

The mass ratio (R / W) of the organic resin (R) and the organic silicon compound (W) in the coating film is preferably 1.0 to 3.0. When R / W is 1.0 or more, cohesive failure hardly occurs in the coating at the time of processing, and the processing adhesion is improved. When R / W is 3.0 or less, the effect of including the organosilicon compound (W) is sufficiently obtained, and a coating film having high hardness is obtained.

The organosilicon compound (W) can be produced, for example, by dissolving or dispersing the above silane coupling agent in water and stirring the mixture at a predetermined temperature for a predetermined time to obtain a hydrolyzed condensate.

The coating film containing the organosilicon compound (W) can be produced, for example, by preparing an aqueous or alcoholic solution containing the organosilicon compound (W) as a raw material of a coating composition for film formation, Applying the coating liquid on the plating layer, and drying the coating liquid.

The aqueous liquid or alcohol-based liquid containing the organosilicon compound (W) can be obtained by, for example, a method of dissolving or dispersing an organosilicon compound such as a hydrolyzed condensate of a silane coupling agent in water to obtain an aqueous liquid, A method of dissolving an organosilicon compound such as a hydrolysis-condensation product of an organic solvent in an alcohol-based organic solvent such as methanol, ethanol or isopropanol to obtain an alcohol-based liquid.

In producing an aqueous liquid or an alcohol-based liquid containing the organosilicon compound (W), it is preferable to add a silane coupling agent or its hydrolysis in an aqueous liquid or an alcohol-based liquid in addition to the organic silicon compound (W) In order to dissolve or disperse the condensate, an acid, an alkali, an organic solvent, a surfactant, and the like may be added. In particular, it is preferable to add an organic acid in addition to water or an alcohol-based organic solvent to adjust the pH of the aqueous liquid or the alcohol-based liquid to 3 to 6 from the viewpoint of the storage stability of the aqueous liquid or the alcohol-based liquid.

It is preferable that the solid concentration of the organic silicon compound (W) in the aqueous liquid of the organic silicon compound (W) or the alcohol-based liquid is 25 mass% or less. When the solid concentration of the organosilicon compound (W) is 25 mass% or less, the storage stability of the aqueous liquid or the alcohol-based liquid becomes good.

It is preferable that the coating film contains carbon black (C) as a coloring pigment. When carbon black is contained in the coating film, fine unevenness existing on the surface of the coating layer is concealed, resulting in a beautiful black appearance, and excellent designability can be obtained.

Examples of the carbon black (C) contained in the coating film include known carbon blacks such as furnace black, ketjen black, acetylene black and channel black. As the carbon black (C) contained in the coating film, carbon black to which a known ozone treatment, plasma treatment, or liquid phase oxidation treatment has been applied may be used.

The particle diameter of the carbon black (C) contained in the coating film is not particularly limited as long as it does not affect the dispersibility in the coating composition for forming a film, the quality of the coating film, and the paintability. When carbon black is dispersed in an aqueous solvent, it aggregates in the course of dispersion. For this reason, it is generally difficult to disperse carbon black in an aqueous solvent while maintaining the primary particle diameter. Therefore, the carbon black contained in the coating composition for coating film exists in the form of secondary particles having a particle diameter larger than the primary particle diameter. Therefore, carbon black in the coating film formed using the coating composition also exists in the form of secondary particles as in the case of the coating composition.

As the carbon black used as a raw material for the coating film, for example, those having a primary particle diameter of 10 nm to 120 nm can be used. Considering the designability and the barrier property of the coating, it is preferable that the particle diameter of the carbon black contained in the coating is 10 nm to 50 nm.

In order to ensure the design and barrier properties of the coating, the diameter of the carbon black particles in the form of secondary particles dispersed in the coating is important. The average particle diameter of the carbon black in the coating film is preferably 20 nm to 300 nm.

The content of the carbon black (C) contained in the film is preferably 1 to 20 mass%, more preferably 3 to 15 mass%, and most preferably 5 to 13 mass%. When the content of the carbon black (C) contained in the coating film is 1% by mass or more, a uniform black appearance is obtained. When the content of the carbon black (C) contained in the film is 20 mass% or less, the content of other raw materials of the carbon black (C) contained in the film can be ensured, and excellent barrier properties can be obtained.

The film may contain a fluorometal complex (F). The fluoro metal complex (F) acts as a cross-linking agent in the coating to improve cohesion of the coating. The fluorometal complex (F) is not particularly limited, but from the viewpoint of barrier property, it is preferable to use a fluorometallic complex having titanium. Examples of such fluoro metal complex (F) include titanium hydrofluoric acid.

The coating film may contain polyethylene wax (Q). The polyethylene wax (Q) can improve the scratch resistance of the coating. Therefore, when the polyethylene wax (Q) is contained in the coating film, the lubricity of the surface treated steel sheet is increased, and for example, the frictional resistance due to the contact between the steel sheet and the press metal is reduced, It is possible to prevent a scratch on handling.

The polyethylene wax (Q) contained in the coating film is not particularly limited and a known lubricant can be used. Concretely, it is preferable to use a polyolefin resin-based lubricant as the polyethylene wax (Q).

The polyolefin resin-based lubricant used as the polyethylene wax (Q) is not particularly limited, and for example, a hydrocarbon wax such as polyethylene may be used.

The content of the polyethylene wax (Q) contained in the coating film is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 5% by mass or less, When the content of the polyethylene wax (Q) is 0.5% by mass or more, the effect of improving scratch resistance is obtained. When the content of the polyethylene wax (Q) is 10 mass% or less, the content of the other raw materials of the polyethylene wax (Q) contained in the film can be ensured and excellent barrier property can be obtained.

&Quot; Method of producing surface-treated steel sheet 10 "

Next, a method of manufacturing the surface-treated steel sheet 10 will be described.

The method for producing a surface-treated steel sheet according to the present embodiment is characterized in that a plating bath containing 0.10 to 4.00 mol / l of Zn ²⁺ ions, 0.01 to 2.00 mol / l of V ions or 0.10 to 4.00 mol / l of Zr ions A step of forming an irregularity by depositing vanadium oxide or vanadium hydroxide hydrated on the steel sheet 1 by electroplating at a current density of 0 to 18 A / dm 2, 1) having an upper layer plating step of carrying out electroplating at a current density of 21 to 200 A / dm 2 using the above-described plating bath. The above ground forming step is a factor affecting V / Zn which is the molar ratio of the vanadium and the zinc in the intergranular charged region in the plating layer. When the current density in the ground formation step exceeds 18 A / dm 2, V / Zn, which is the molar ratio of vanadium and zinc in the intergranular filling region, becomes less than 0.10.

In this embodiment, pretreatment is performed on both surfaces of the steel sheet 1 forming the plating layer 30, if necessary. As the pretreatment, it is preferable to perform nickel plating with a thickness of 1 to 300 nm on both surfaces of the steel sheet 1 to form the ground layer 20.

Next, a plating layer 30 is formed on one surface or both surfaces of the steel sheet 1. In the present embodiment, a method of forming the plating layer 30 on both surfaces of the steel sheet 1 by electroplating is explained using the plating apparatus shown in Fig. 3 as an example.

3 is a schematic view showing an example of the plating apparatus. In this embodiment, among the rolls 4a, 4b, 5a, and 5b, the rolls 4a and 4b disposed on the upper side of the steel plate 1 are electrically connected to a power source (not shown) And functions as a connecting member (conductor). The steel strip 1 is electrically connected to the rolls 4a and 4b, thereby forming a negative electrode. In the case of electroplating, a plurality of plating apparatuses shown in Fig. 3 are arranged in series and used. The ground forming process is carried out in the plating apparatus shown in Fig. 3 or in the region surrounded by the rolls of reference numerals 4a and 5a in Fig. 3 and the intermediate branch lines of 2d and 2f. The upper layer plating process is carried out in the plating apparatus shown in Fig. 3, or in the region surrounded by the intermediate branch paths 2d and 2f and the rolls 4b and 5b in Fig.

The plating tank 21 has an upper tank 21a disposed on the upper side of the steel plate 1 and a lower tank 21b disposed on the lower side of the steel plate 1. [

3, a plurality of positive electrodes 3 made of platinum or the like are provided between the upper plate 21a and the lower tank 21b at a position adjacent to the steel plate 1 with respect to the steel plate 1 And are arranged at predetermined intervals. The surface of each anode 3 facing the steel sheet 1 is arranged so as to be substantially parallel to the surface of the steel sheet 1. Each of the positive electrodes 3 is electrically connected to a power source (not shown) by a connecting member (not shown).

The inside of the upper tank 21a and the inside of the lower tank 21b are filled with the plating bath 2. As shown in Fig. 3, a steel plate 1 is disposed between the upper tank 21a and the lower tank 21b of the plating tank 21 and moving in the plane direction substantially horizontally. The steel sheet 1 passing through the plating bath 21 in the direction of the arrow by the rolls 4a, 4b, 5a and 5b is fed to the plating bath (not shown) in the upper tank 21a and the lower tank 21b 2). Therefore, in the present embodiment, the steel plate 1 is transported by the rolls 4a, 4b, 5a and 5b, and the steel plate 1 is moved in the plating bath 2, And a plating bath 2 in a fluidized state in which the bath 2 relatively flows.

3, the upper tank 21a is provided with an upper supply pipe 2a for supplying the plating bath 2 to the upper tank 21a so as to pass through the upper surface of the upper tank 21a . The upper supply pipe 2a is branched into a plurality of outer peripheral branch paths 2c and a plurality of intermediate branch paths 2d (only one is shown in Fig. 3) in the upper tank 21a. A plurality of intermediate branch passages (2d) are arranged between the adjacent positive electrodes (3) in plan view along the width direction of the steel plate (1). The intermediate branch path 2d has an opening for supplying the plating bath 2 between the anode 3 and the steel plate 1 on both sides. A plurality of outer circumferential branch paths 2c are arranged between the anode 3 and the rolls 4a and 4b in plan view along the width direction of the steel plate 1. [ The outer circumferential branch path 2c has an opening for supplying the plating bath 2 between the anode 3 and the steel plate 1. [

A discharge port (not shown) for discharging the plating bath 2 is formed in the upper tank 21a and is connected to the upper supply pipe 2a through a pipe (not shown) having a pump . Therefore, in the upper tank 21a, the plating bath 2 supplied from the upper supply pipe 2a and discharged from the discharge port is supplied from the upper supply pipe 2a again through the pipe, and circulated The plating bath 2 is in a fluidized state.

The lower tank 21b is provided with a lower supply pipe 2b for supplying the plating bath 2 to the lower tank 21b so as to pass through the lower surface of the lower tank 21b. The lower supply pipe 2b branches into a plurality of outer peripheral branch paths 2e and a plurality of intermediate branch paths 2f (only one is shown in Fig. 3) in the lower tank 21b. A plurality of intermediate branch paths 2f are arranged between the adjacent positive electrodes 3 in plan view along the width direction of the steel plate 1. [ The intermediate branch path 2f is provided with an opening for supplying the plating bath 2 between the anode 3 and the steel plate 1 on both sides. A plurality of outer circumferential branch paths 2e are arranged between the anode 3 and the rolls 5a and 5b in plan view along the width direction of the steel plate 1. [ The outer peripheral branch path 2e has an opening for supplying the plating bath 2 toward the space between the anode 3 and the steel plate 1. [

A discharge port (not shown) for discharging the plating bath 2 is formed in the lower tank 21b and is connected to the lower supply pipe 2b through a pipe (not shown) having a pump . Therefore, in the lower tank 21b, the plating bath 2 supplied from the lower supply pipe 2b and discharged from the discharge port is supplied from the lower supply pipe 2b through the pipe again by the pump, The plating bath 2 is in a fluidized state.

When the energization time in the ground formation step is adjusted to 0.05 second to 8.00 second, the amorphous diffraction pattern stably appears in the inter-crystal charged region 32.

In the present embodiment, it is assumed that the plating layer 30 is formed on the surface of the steel sheet 1 by the following mechanism. 4A to 4C are schematic diagrams for explaining the state of the surface of the steel sheet 1 in the step of manufacturing the surface-treated steel sheet 10 shown in Fig.

In the plating apparatus shown in Fig. 3, a portion of the steel sheet 1 having a nickel plated layer (base layer) 20a formed on the surface thereof passes sequentially between the rolls 4a and 5a, and is brought into contact with the plating bath 2 sequentially Plating is started at a current density of 18 A / dm 2 or less.

That is, the rolls 4a and 5a are rolls for energizing and are also called conductor rolls. The steel sheet and the plating solution contact each other after passing between the conductor rolls 4a and 5a.

In this embodiment, before the zinc is deposited on the surface (solid-liquid interface) of the steel sheet 1 on which the nickel plating layer 20a having passed between the rolls 4a and 5a is formed, as shown in Fig. 4A , A vanadium compound (6) containing hydrated vanadium oxide or vanadium hydroxide is precipitated to form irregularities.

This is presumably because, at a current density of 18 A / dm 2 or less, vanadium having a high precipitation potential is reduced and precipitated, but zinc having a low precipitation potential is not precipitated. Further, in the above ground forming step, the vanadium compound (6) containing hydrated vanadium oxide or vanadium hydroxide precipitates. This is different from the base layer 20 described above. This plating is finally introduced into the plating layer 30. [

When the precipitation of the vanadium compound 6 on the surface of the steel sheet 1 is started in the ground formation step, a plurality of current concentration portions 61 are formed on the surface of the steel sheet 1 as shown in Fig. 4A . It can be inferred that the current concentrating portion 61 is a portion in which current flows, which is a portion of the surface of the steel plate 1 where the vanadium compound 6 is not precipitated or a portion where the amount of precipitation is small.

When the current density is 21 A / dm 2 or more, the Zn deposition potential is reached, and the Zn precipitation reaction starts. The dendritic phase crystal 3a containing zinc metal grows as shown in Fig. 4B, and the upper layer plating process is started. When the dendritic phase crystal 3a grows, it is presumed that the crystal grows more easily at the tip of the dendritic phase crystal 3a.

In the upper plating process, as the dendritic phase crystal 3a grows, current is concentrated on the tips of the branched plural branch portions of the dendritic phase crystal 3a, and as shown in Fig. 4C, It is presumed that hydrogen 62 is generated at the liquid interface of the plating bath 2 at the tip.

The hydrogen 62 thus generated increases the pH of the surface of the dendritic phase crystal 3a and the solid-liquid interface of the plating bath 2. As a result, crystals containing zinc oxide or zinc hydroxide are precipitated so as to cover the surface of the dendritic phase crystal 31 to form the dendritic phase crystal 31 having the surface layer 3b shown in Fig. 1 . Amorphous material containing hydrated vanadium oxide or vanadium hydroxide is precipitated between adjacent dendritic phase crystals 31 by the rise of the pH of the plating bath 2, 32 are formed.

In this embodiment, as described above, the energization time is controlled in the range of 0.05 to 8.00 seconds in the ground forming step. Therefore, before deposition of zinc on the surface of the steel sheet 1, deposition of the vanadium compound 6 starts, and a plurality of current concentration portions 61 are formed on the surface of the steel sheet 1. As a result, by the above-described mechanism, it is assumed that the dendritic phase crystal 31 is obtained, and the intercalciferous filling region 32 showing an amorphous diffraction pattern is obtained when electron beam diffraction is performed. It is more preferable that the moving time of the steel strip 1 passing through the interval D is in the range of 1.00 to 6.00 seconds.

If the electrification time of the ground forming process is less than 0.05 second, the precipitation amount of the vanadium compound (6) precipitated before the zinc is deposited on the surface of the steel sheet (1) is insufficient. This makes it difficult for the dendritic phase crystal 31 made of metal zinc to grow in the current concentration portion 61 formed on the surface of the steel sheet 1. [ Further, even if the intercalciferous charging region 32 containing hydrated vanadium oxide or vanadium hydroxide is not obtained or the intercalciferous charging region 32 is obtained, the amorphous diffraction pattern may become unstable.

If the energization time of the ground forming process exceeds 8.00 seconds, the deposition amount of the vanadium compound (6) precipitated before the deposition of zinc on the surface of the steel sheet (1) becomes too large, The number of the portions 61 decreases or disappears. This makes it difficult for the dendritic phase crystal 31 made of metal zinc to grow and the dendritic phase crystal 31 and the intercalciferous filling region 32 can not be obtained or the intercalciferous filling region 32 is obtained The diffraction pattern of the amorphous state becomes unstable.

In the present embodiment, it is preferable to perform electroplating under the condition that the current density is 0 to 18 A / dm 2 in the ground forming step, and it is more preferable to conduct the electroplating under the condition that the current density is 2 to 15 A / dm 2 Do. When the current density in the base forming process is 18 A / dm 2 or less, the molar ratio (V / Zn) of vanadium and zinc in the intergranular filling region 32 becomes 0.10 or more and 2.00 or less, The inter-crystalline charged region 32 exhibits an amorphous diffraction pattern, and as a result, the barrier property and the film adhesion can be improved. On the other hand, if the current density in the ground formation step is not in the above range, the amorphous diffraction pattern becomes unstable even if the intercalation filling region 32 is not formed or the intergranular filling region 32 is formed.

In the upper layer plating step, electroplating is preferably performed under the condition that the current density is 21 to 200 A / dm 2. When the current density is 21 A / dm 2 or more, the hydrogen 62 can be sufficiently generated at the tip of the branch portion of the dendritic phase crystal 31 and at the solid-liquid interface of the plating bath 2. Therefore, the precipitation amount of hydrated vanadium oxide or vanadium hydroxide contained in inter-crystalline charged region 32 is increased. Therefore, the plating layer 30 having a large vanadium content and excellent barrier properties can be formed. If the current density exceeds 200 A / dm 2, the plating structure becomes rough or cracks tend to occur, so that the adhesion between the plating layer 30 and the steel sheet 1 may be deteriorated.

The average flow velocity of the plating bath 2 in the plating bath 21 when plating is preferably in the range of 20 to 300 m / min, more preferably in the range of 40 to 200 m / min. It is possible to prevent the occurrence of cracks in the plating layer 30 and to prevent the occurrence of cracks on the surface of the steel sheet 1 from the plating bath 2 when the average flow rate of the plating bath 2 is in the range of 20 to 300 m / It is possible to supply the ions of the second conductivity type without any hindrance.

As the plating bath 2, one containing a V compound and a Zn compound is used. In addition to the V compound and the Zn compound, a pH adjuster, a V compound, and other metal compounds and additives other than the Zn compound may be added to the plating bath 2, if necessary.

Examples of the pH adjuster include H ₂ SO ₄ and NaOH.

Examples of the additive include Na ₂ SO ₄ which stabilizes the conductivity of the plating bath 2.

Examples of other metal compounds include nickel compounds such as NiSO ₄ .6H ₂ O and the like. When the plating bath 2 contains a nickel compound, it is preferable that the plating bath 2 contains Ni ²⁺ in an amount of 0.01 mol / l or more. As a result, the plating layer 30 containing nickel sufficiently can be formed. The plating layer 30 containing nickel is preferable because good plating adhesion is obtained.

Examples of the Zn compound used in the plating bath 2 include metal Zn, ZnSO ₄ .7H ₂ O and ZnCO ₃ . These may be used alone or in combination of two or more.

Examples of the V compound used in the plating bath 2 include ammonium metavanadate (V), potassium metavanadate (V), metavanadate oxygen da (V), VO (C ₅ H ₇ O ₂ ) ₂ Diacetylacetonate (IV)), VOSO _4. 5H ₂ O (vanadyl sulfate (IV)), and the like. These may be used alone or in combination of two or more.

As the plating bath 2, it is preferable to use Zn ²⁺ and VO ²⁺ .

If the plating bath (2) comprises a Zn ^2+, it is desirable, and more preferably containing 0.35 to 2.00mol / l including a Zn ²⁺ 0.10 to 4.00mol / l.

When the plating bath 2 includes VO ^{2 +} , it is preferable that VO ²⁺ be contained in the plating bath ² in the range of 0.01 mol / l to 2.00 mol / l. By using the plating bath 2 containing VO ²⁺ within the above range, the plating layer 30 having a large vanadium content and excellent barrier properties can be easily formed. When the content of VO ²⁺ contained in the plating bath 2 is less than the above range, it becomes difficult to secure the vanadium content in the plating layer 30. If the content of VO ²⁺ contained in the plating bath 2 exceeds the above range, expensive vanadium is used in the plating bath 2, which is economically disadvantageous.

As the plating bath 2, it is preferable to use a plating bath 2 containing 0.10 mol / l or more of Na ^< ^{+ &} gt ;. In this case, the conductivity of the plating bath 2 can be increased, and the plating layer 30 of the present embodiment can be easily formed.

The temperature of the plating bath 2 is not particularly limited, but is preferably in the range of 40 to 60 占 폚 in order to easily and efficiently form the plating layer 30 of the present embodiment.

The pH of the plating bath 2 is preferably in the range of 1 to 5, more preferably in the range of 1.5 to 4, in order to easily form the plating layer 30 of the present embodiment.

In the present embodiment, after forming the plating layer 30, a treatment agent for improving the barrier property, the smoothness, the scratch resistance, the lubricity, the decorative property, and the like is applied on the plating layer 30 as necessary, .

By the above process, the surface-treated steel sheet 10 shown in Fig. 1 is obtained.

&Quot; Second embodiment, surface-treated steel sheet 210 "

Hereinafter, the surface treated steel sheet 210 of the second embodiment in the case where the plating layer 230 contains zirconium will be described.

The surface treated steel sheet 210 of the present embodiment includes a steel sheet 201 and a plating layer 230 formed on one surface or both surfaces of the steel sheet. The plating layer 230 contains zinc and zirconium. The plating layer 230 contains a dendritic phase crystal 231 containing metal zinc and an intercalcary charge region 232 containing one or both of hydrated zirconium oxide or zirconium hydroxide. Hereinafter, the surface treated steel sheet 210 will be described in detail.

Since the steel plate 201 is the same as the steel plate 1 of the first embodiment, a description thereof will be omitted.

As described above, the plating layer 230 has a dendritic phase crystal 231 containing metal zinc and an intercalary charge region 232 containing one or both of hydrated zirconium oxide or zirconium hydroxide.

The dendritic phase crystal 231 is a dendritic crystal phase containing metal zinc, and the intercalciferous charging region 232 contains one or both of hydrated zirconium oxide or zirconium hydroxide, and the dendritic phase crystal 231 And has an amorphous pattern by electron beam diffraction.

The plating layer 230 has a form in which the dendritic phase crystal 231 is deposited first and then the intergranular charged region 232 is deposited around the dendritic phase crystal 231.

As described above, the dendritic phase crystal 31 of the first embodiment has an inner portion 3a and a surface layer 3b. As described above, the inside 3a of the dendritic phase crystal 31 preferably contains metal zinc, and may contain other metal components such as nickel. On the other hand, the surface layer 3b of the dendritic phase crystal 31 preferably contains zinc oxide or zinc hydroxide, and more preferably contains crystals of hydrated zinc oxide. On the other hand, the dendritoid phase crystal 231 of the present embodiment does not have an interior and a surface layer.

The dendrite phase crystals 231 may be formed only of metal zinc, or may contain other metal components such as nickel, which is more attractive than the precipitation potential of zinc, together with metal zinc. The dendritic phase crystal 231 has a structure in which it grows from the steel plate 201 side toward the surface side of the plating layer 230 along the thickness direction of the plating layer 230 and branches toward the surface of the plating layer 230. When the dendritic phase crystal 231 contains metallic zinc, a sacrificial anticorrosion property can be imparted to the plating layer 230.

The intercrystalline fill region 232 may contain zinc oxide in addition to containing either or both of hydrated zirconium oxide or zirconium hydroxide. By including these inclusions in the inter-crystalline charged region 232, the plating layer 230 can be given barrier properties. In addition, since the inter-crystalline charged region 232 mainly contains hydrated oxides or hydroxides, the film adhesion can be ensured when the inter-crystalline charged region 232 is formed with a coated film.

The inter-crystalline charged region 232 exhibits an amorphous diffraction pattern when electron beam diffraction is performed.

It is preferable that the molar ratio (Zr / Zn) of zirconium and zinc in intercrystalline filled region 232 is 1.00 or more and 3.00 or less when intercalated region 232 includes hydrated zirconium oxide or zirconium hydroxide and zinc oxide. When the above-mentioned molar ratio (Zr / Zn) is in the above range and the intergranular filling region 232 exhibits an amorphous diffraction pattern when electron beam diffraction is performed, excellent corrosion resistance (barrier property) and coating film adhesion are obtained.

In the upper layer of the plating layer 230, an amorphous layer 250 exhibiting an amorphous diffraction pattern may be formed when electron beam diffraction is performed.

It is assumed that the amorphous layer 250 is formed first when the plating layer 230 is formed. That is to say, the amorphous layer 250 is first formed on the steel plate 201 and then the dendritic phase crystal 231 and intercrystalline charged region 232 are formed between the steel plate 201 and the amorphous layer 250 It is presumed that the plating layer 230 containing the metal is grown.

The amorphous layer 250 is a layer mainly composed of zirconium oxide, and may contain a small amount of zinc. The amorphous layer 250 is formed on the upper layer of the plating layer 230, thereby exhibiting barrier properties.

After the plating layer 230 is formed, the amorphous layer 250 can be removed by immersing the steel plate 201 having the plating layer 230 in an acidic solution. The amorphous layer 250 may be removed from the surface-treated steel plate 201 by such a process.

The amorphous layer 250 is removed, and the plating layer 230 is exposed. The surface of the plated layer 230 has a higher surface roughness than the amorphous layer 250 and is superior in adhesion to the coating film as compared with the case where the amorphous layer 250 is formed.

The adhesion amount of the plating layer 230 is preferably 1 g / m 2 or more and preferably 3 g / m 2 or more in order to improve the barrier property. The amount of the plating layer 230 deposited is preferably 60 g / m 2 or less, more preferably 40 g / m 2 or less, and further preferably 20 g / m 2 or less. When the deposition amount of the plating layer 230 is 20 g / m 2 or less, the metal amount to be precipitated is smaller than that of the conventional electroplating (usually about 20 g / m 2) or the like. Also, if the adhesion amount is too large, cracks tend to occur in the plating layer 230.

The thickness of the plating layer 230 is preferably in the range of 0.5 to 40 占 퐉, more preferably in the range of 1.0 to 20 占 퐉, and further preferably in the range of 2.0 to 15 占 퐉. When the thickness of the plating layer 230 is at least the lower limit, the barrier property can be improved. If the thickness of the plating layer 230 is less than the upper limit, cracks are less likely to occur in the plating layer 230. The thickness of the plating layer 230 can be controlled by adjusting the amount of electric power to be applied when electroplating.

The thickness of the amorphous layer 250 is preferably in the range of 0.20 to 2.00 mu m, more preferably in the range of 0.30 to 1.50 mu m, and further preferably in the range of 0.50 to 1.00 mu m. When the thickness of the amorphous layer 250 is not less than the upper limit, barrier properties can be imparted to the plating layer 230. When the thickness of the amorphous layer 250 is less than the lower limit, generation of cracks can be prevented and barrier properties can be ensured. The thickness of the amorphous layer 250 can be controlled by adjusting the Zr concentration in the plating bath at the time of electroplating. That is, as the Zr concentration in the plating bath at the time of electroplating is increased, the thickness of the amorphous layer 250 can be increased.

The plating layer 230 has an average concentration of 3 to 40 atm% of Zr, 3 to 40 atm% of Zn, and residual oxygen and impurities. When Zr in the plating layer 230 is 3 atm% or more, the barrier property can be enhanced. If Zr in the plating layer 230 is 40 atm% or less, cracking in the plating layer 230 can be prevented, and barrier properties can be ensured. If the amount of Zn in the plating layer 230 is 3 atm% or more, a sacrificial effect can be given to the plating layer 230. If the Zn content in the plating layer 230 is 40 atm% or less, the amount of Zr can be relatively secured, and the barrier property of the plating layer 230 can be improved.

The dendritic phase crystal 231 contains metal Zn as described above, and may further contain Ni or the like.

When the electron beam diffraction is performed from the end face of the plating layer 230 using a transmission electron microscope (TEM), a diffraction pattern attributable to the crystal structure is obtained in the dendritic phase crystal 231.

The inter-crystalline charged region 232 is composed of an average concentration of Zr: 10 to 80 atm%, Zn: 3 to 40 atm%, residual oxygen and impurities. When the Zr in the inter-crystalline charged region 232 is 10 atm% or more, the barrier property can be enhanced. In addition, when the Zr in the inter-crystalline charged region 232 is 80 atm% or less, the occurrence of cracks in the plating layer 230 can be prevented, and the barrier property can be ensured. Further, when the amount of Zn in the inter-crystalline charged region 232 is 3 atm% or more, the barrier property can be enhanced. If the amount of Zn in the inter-crystalline charged region 232 is 40 atm% or less, the amount of Zr can be relatively secured, and the barrier property of the plating layer 230 can be improved.

The amorphous layer 250 has an average concentration of 10 to 60 atm% of Zr, 0 to 15 atm% of Zn, and residual oxygen and impurities. When Zr in the amorphous layer 250 is 10 atm% or more, the barrier property can be enhanced. When the amount of Zr in the amorphous layer 250 is 60 atm% or less, generation of cracks can be prevented and barrier properties can be ensured. The amorphous layer 250 may contain a small amount of Zn or may not contain Zn.

The ground layer 220 may be formed between the steel plate 201 and the plating layer 230 in the same manner as in the first embodiment.

The surface layer 240 may be formed on the upper layer of the plating layer 230 (the amorphous layer 250 when the amorphous layer 250 is formed), as in the first embodiment.

The surface treated steel sheet 210 of the present embodiment has a L * value indicating brightness of 40 or less, and has a black appearance. By having a black appearance, it can be used for various purposes. When the L * value exceeds 40, it is difficult to use it as a material having a black appearance. In particular, by setting the Zr concentration in the plating layer 230 to 5 mass% or more, the L * value can be reliably set to 40 or less.

The surface treated steel sheet 210 according to the present embodiment has been described by way of example in which the plating layer 230 is formed on the steel sheet 201. The present embodiment is not limited to this example but may be applied to an electroded galvanized steel sheet, , The plating layer 230 of the present embodiment may be formed on the galvanized layer of the galvannealed galvanized steel sheet. That is, a second zinc plated layer (not shown) containing zinc may be further formed between the steel plate 201 and the plating layer 230. By further forming the second zinc plating layer (not shown), the corrosion resistance of the surface treated steel sheet 210 can be further improved. For example, even when the corrosive substance passes through the plating layer 230, the sacrificial effect can be exhibited by the second zinc plating layer (not shown), and the corrosion resistance of the surface treated steel sheet 210 can be improved.

&Quot; Method of manufacturing surface-treated steel sheet 210 "

Next, a method of manufacturing the surface-treated steel sheet 210 will be described. The method for producing the surface-treated steel sheet 210 differs from the method for manufacturing the surface-treated steel sheet 1 according to the first embodiment only in the composition of the plating bath,

The surface-treated steel sheet 210 has a ground forming step and an upper layer plating step, similarly to the first embodiment. A plating bath containing a Zr compound (ZrO ²⁺ ) and a Zn compound (Zn ²⁺ ) is used, which uses the same plating bath in the ground forming step and the upper layer plating step.

As the Zr compound, it is preferable to form ZrO ^{2 +} ions in the plating bath, and examples thereof include soluble salts such as zirconium nitrate, zirconium sulfate, and zirconium chloride nitrate. These may be used alone or in combination of two or more.

The plating bath preferably contains Zn ^{2+ in an amount} of 0.10 to 4.00 mol / l, more preferably 0.50 to 2.00 mol / l. Further, the content of ZrO ²⁺ is preferably 0.10 to 4.00 mol / l, more preferably 0.50 to 2.00 mol / l. By using a plating bath containing ZrO2 ⁺ within the above range, the plating layer 230 having a high Zr content and excellent barrier properties can be easily formed. When the content of ZrO ²⁺ contained in the plating bath is less than the above range, it becomes difficult to secure the Zr content in the plating layer 230. Further, if the content of ZrO ²⁺ contained in the plating bath exceeds the above range, Zr is used in a large amount in the plating bath 2, which is economically disadvantageous.

In addition to the Zr compound and the Zn compound, a pH adjuster, a Zr compound, and other metal compounds other than the Zn compound, an additive, and the like may be added to the plating bath, if necessary.

Since the current density in the ground forming process and the upper layer plating process is the same as that in the first embodiment, description thereof will be omitted.

"Another example"

The present invention is not limited to the above-described embodiments.

In the present embodiment, the case where the plating layer is formed on both surfaces of the steel sheet has been described as an example, but the plating layer may be formed only on one surface of the steel sheet.

Further, it is preferable that a ground layer is formed between the steel sheet and the plating layer, but the ground layer may not be formed. In the case where a plating layer is formed on both surfaces of the steel sheet, a base layer may be formed only between the steel sheet and the plating layer on one side.

In the present embodiment, the case where the plating layer contains vanadium and the case including zirconium are separately described, but these embodiments may be provided at the same time.

In the present embodiment, the case where the surface layer is formed on the surface of the plating layer is described as an example, but the surface layer may not be formed. Since the surface treated steel sheet of the present embodiment is excellent in barrier property, it is not necessary to form a surface layer for improving the barrier property on the surface of the plating layer. When a plating layer is formed on both surfaces of the steel sheet, a surface layer may be formed only on the surface of the plating layer on one side.

In the present embodiment, the case of manufacturing the surface-treated steel sheet by using the plating apparatus shown in Fig. 3 has been described as an example. However, the plating apparatus for producing the surface-treated steel sheet is limited to the plating apparatus shown in Fig. 3 It is not. For example, in the plating apparatus shown in Fig. 3, four positive electrodes 3 are arranged, but the number of positive electrodes 3 may be several. The size and shape of the plating vessel 21, the steel plate 1 and the anode 3 and the arrangement and shape of the upper supply pipe 2a and the lower supply pipe 2b are not particularly limited, The use of the treated steel sheet 10 and the like.

Example  One

&Quot; Test results of vanadium-containing surface-treated steel sheet "

Using the plating apparatus shown in Fig. 3, a surface-treated steel sheet having a plating layer containing vanadium on both surfaces of the steel sheet was produced and evaluated by the following method.

A plating bath in a fluidized state was prepared by circulating a plating bath having the plating bath composition, temperature, and pH shown in Table 1 at a relative average flow rate of 100 m / min.

As the steel sheet, a sheet having a thickness of 0.5 mm of SPCD used for drawing a cold-rolled steel sheet specified in JIS G 3141 was used.

The above steel sheet was pretreated (nickel plated) and used as a negative electrode.

First, as the plating bath for nickel plating, ion-exchanged water, concentrated sulfuric acid and NiSO ₄ .6H ₂ O were mixed to prepare a coating solution containing 60 g / L as Ni ²⁺ and having a pH of 2.0 Respectively. Then, the steel sheet was immersed in a plating bath to carry out an electrolytic treatment so that the steel sheet was used as a negative electrode and the Ni deposition amount was 200 mg / m 2 as a positive electrode using a platinum electrode.

In each of the ground forming step and the upper layer plating step, each of the energizing times was set to a time shown in Tables 2 and 3, and a plating layer was formed by an electroplating method.

In the plating bath composition shown in Table 1, ZnSO ₄ .7H ₂ O was used as the Zn compound, VOSO ₄ .5H ₂ O was used as the V compound, and Na ₂ SO ₄ and other metal compounds NiSO ₄ .6H ₂ O was used. These contents were adjusted so that the concentrations of Zn ²⁺ , V (V ⁴⁺ , VO ²⁺ ), Na ⁺ and Ni ²⁺ shown in Table 1 were obtained.

The plating layers of the thus-obtained examples and comparative examples were observed with a field emission transmission electron microscope (FE-TEM) (JED-2100F).

5A to 5C are transmission electron microscope (TEM) photographs of a plating layer of a surface-treated steel sheet of Example V4. 5A is an enlarged view of the interface portion between the steel sheet and the plating layer in the cross section of FIG. 5A, FIG. 5C is an enlarged view of FIG. 5A, Fig. 5 is an enlarged photograph of a dendritic phase crystal and its peripheral portion in a cross section. Fig.

In Fig. 5B, reference numeral 51 denotes a base layer, and reference numeral 52 denotes an intergranular filling region in the vicinity of the interface between the steel sheet and the plating layer. 5C, reference numeral 53 is a dendritic phase crystal, 54 is an intergranularly charged region, and 55 is a surface layer formed on the surface of the dendritic phase crystal.

As shown in Figs. 5A to 5C, in the surface treated steel sheet of Example V4, the surface layer of the dendritic phase crystal, the intergranular filled region, and the dendrite phase was formed in the plating layer.

The plating layers of the surface-treated steel sheets of Examples V1 to V3 and V5 to V20 were also observed using TEM in the same manner as in Example V4. As a result, the surface layer of the dendritic phase crystal, the intergranular charged region, and the dendrite phase was formed in the plating layer.

The plating layer of the surface-treated steel sheet of Example V4 was observed using a scanning electron microscope (SEM: A-4300SE, manufactured by Hitachi Seisakusho Co., Ltd.) from the cross-sectional direction. The plating layer was observed after depositing a gold film on the surface of the plating layer in order to make it easy to observe the surface shape of the plating layer.

6 is a scanning electron microscope (SEM) photograph of the plating layer of the surface-treated steel sheet of Example V4. 6, reference numeral 56 is a dendritic phase crystal, 57 is an intercrystalline charged region disposed between dendrite phase crystals, and 58 is a surface layer covering the surface of the dendritic phase crystal. Further, in the photograph shown in Fig. 6, the white part of the surface of the plating layer is a gold film deposited for observation of the plating layer.

The plating layers of the surface-treated steel sheets of Examples V1 to V3 and V5 to V20 also had a surface layer of dendritic phase crystal, intergranular filling region and dendritic phase crystal similarly to the plating layer of Example V4.

The plating layers of the surface-treated steel sheets of Comparative Examples x1 to x7 were observed using SEM in the same manner as in Example V4. 7 is a scanning electron microscope (SEM) photograph of the plating layer of the surface-treated steel sheet of Comparative Example x2. As shown in Fig. 7, the plating layer of Comparative Example x2 was a single phase comprising a dendritic phase crystal.

The plating layers of Examples V1 to V20 were each coated with a dendritic phase crystal, an intercrystalline charged region, a dendrite (JED-2300T) using an energy dispersive X-ray analyzer (EDS) Elemental analysis of the surface layer of the phase crystal was performed. The element (composition) included in the dendritic phase crystal, the element (composition) included in the intercrystalline charged region, the amount of vanadium and the amount of zinc, and the element (composition) included in the surface layer of the dendritic phase crystal were examined.

Using the results of the elemental analysis, the molar ratio (V / Zn) of the amount of vanadium and the amount of zinc in the inter-crystalline charged region was calculated.

In the plating layers of Comparative Examples x1 to x7, the elemental analysis of the surface layer of the dendritic phase crystal, the intergranular filling region, and the dendritic phase crystal was carried out in the same manner as in Examples V1 to V20.

The results are shown in Tables 4 and 5.

Further, with respect to the plated layer of the surface-treated steel sheets of Examples V1 to V20, the surface of the dendritic phase crystal, the intergranular filling region, and the dendritic phase crystal each had a crystal structure using the electron beam diffraction image obtained by TEM from the cross- And whether it is amorphous or not.

8 is a photograph showing electron diffraction patterns of the plating layer of Example V4. The reference numerals attached to the photographs shown in Fig. 8 are the inter-crystalline charged regions 52, the dendritic phase crystals 53, the intercrystalline charged regions 54, the surface layer of the dendrite phase crystals (Fig. 55).

From the electron diffraction image shown in Fig. 8, it was found that the dendritic phase crystal 53 and the surface layer 55 of the dendritic phase crystal had a crystal structure. It was also found that the inter-crystal charged regions 52 and 54 were amorphous without obtaining a diffraction pattern due to the crystal structure.

The plated layers of the surface-treated steel sheets of Examples V1 to V3 and V5 to V20 were also confirmed in the same manner as in Example V4 to determine whether the surface layer of the dendritic phase crystal, intergranular filling region or dendritic phase crystal had a crystal structure or amorphous Respectively. As a result, it was found that the surface layer of the dendritic phase crystal and the dendritic phase crystal had a crystal structure, and the intergranular charged region was amorphous.

Further, when impurities in the dendritic phase crystal were examined, C, Si, S, Fe, and N were each about 0.1 to 5 atm%.

The plating layers of the surface-treated steel sheets of Comparative Examples x1 to x7 were analyzed using an X-ray diffractometer (XRD: RINT2500 manufactured by Rigaku Corporation). As a result, it was confirmed that the dendritic phase crystal had a crystal structure of Zn with respect to the plating layers of Comparative Examples x1 to x7. (Comparative Examples x1 to x3 and x5) in which only an amorphous diffraction pattern was unstable even if the intergranular filling regions were not formed (Comparative Examples x4 and x6), except for Comparative Example x7, Respectively.

The following items were evaluated for the plating layers of Examples and Comparative Examples by the following methods.

(Deposition amount in the plating layer, vanadium content)

The adhesion amount of the plated layer was determined as the total mass per unit area of Zn element and V element detected using a fluorescent X-ray apparatus (Simultix14 manufactured by Rigaku Corporation). The vanadium content in the plated layer was calculated as a percentage by dividing the amount of the V element detected by the fluorescent X-ray apparatus by the deposition amount.

"Barrier Castle"

Edge and back of the test piece cut out from the surface treated steel sheet were tape-sealed and subjected to a salt spray test (JIS-Z-2371). Then, the white rust occurrence area ratio at the non-silicon portion after 72 hours was visually observed and evaluated according to the following criteria. The white rust occurrence area ratio is a percentage of the area of the white rust occurrence area with respect to the area of the observed area.

(standard)

5: Less than 10% of white rust area

4: White rust occurrence area ratio 10% or more, less than 25%

3: area ratio of white rust is 25% or more, less than 50%

2: White rust occurrence area ratio 50% or more, less than 75%

1: White rust occurrence area ratio 75% or more

"Sacrifice Sexuality"

A coating material (Amilac # 1000, manufactured by Kansai Paint Co., Ltd.) was applied to a test piece cut from the surface-treated steel sheet by bar coating and baked at 140 캜 for 20 minutes to form a film having a dry film thickness of 25 탆. Thereafter, the edge and back surface of the painted test piece were tape-sealed, and the surface was scratched with an NT cutter so as to be in the form of X. [ Then, a salt water spray test (JIS-Z-2371) was carried out, and the time until the redness occurred from the scratches was measured and evaluated according to the following criteria.

(standard)

5: Time to red tide generation: 960 hours or more

4: Time to red emission 720 hours or more, less than 960 hours

3: Time to red emission 480 hours or more, less than 720 hours

2: Time to red rust occurrence: 120 hours or more, less than 480 hours

1: Less than 120 hours until the occurrence of red rust

(Powdering property (adhesion between the plating layer and the steel sheet))

For the powdering test, a 60 ° V bending mold was used. The test piece cut out from the surface treated steel sheet was bended at 60 degrees using a mold having a radius of curvature of 1 mm so that the evaluation surface was inside the bent portion. The powdering property (peeling width (mm)) was evaluated from the peeling state of the peeled plating layer with the tape.

(Coating film adhesion)

A coating material (Amilac # 1000, manufactured by Kansai Paint Co., Ltd.) was applied to a test piece cut from the surface-treated steel sheet by bar coating and baked at 140 캜 for 20 minutes to form a film having a dry film thickness of 25 탆. The obtained coated plate was immersed in boiling water for 30 minutes, and left in a room at room temperature for 24 hours. Thereafter, 100 square checkerboards each having a side of 1 mm on each side were cut into NT cutters and extruded by 7 mm with an Erickson tester. The extrusion convex portions were subjected to peeling test using an adhesive tape to measure the film adhesion ( Number of peelings) was evaluated.

As shown in Tables 6 and 7, all of the surface-treated steel sheets of Examples V1 to V20 satisfied the range of the present invention, and compared with the surface-treated steel sheets of Comparative Examples x1 to x7, And coating film adhesion were excellent.

In the plating layers of the surface-treated steel sheets of Examples V1 to V20 in which the current density in the ground formation step was 0 to 18 A / dm 2, the current density in the ground formation step was 25 A / dm 2, And the coating layer of the surface-treated steel sheet of x3, the molar ratio (V / Zn) of vanadium and zinc in the intergranular filling region is 0.10 or more and 2.00 or less, and when the electron beam diffraction is carried out, The diffraction pattern is shown. Further, it was found that the barrier property and the coating film adhesion were more excellent.

Example 2

&Quot; Test results of surface-treated steel sheets containing vanadium-containing vanadium "

The coating composition for forming the coating film was prepared by mixing the organic resin (R), the phosphoric acid compound (P), the carbon black (C), the organic silicon compound (W), the fluoromethyl complex compound (F) (Isocyanate compound (I) and polyethylene wax (Q) were dispersed in water as a solvent with a content (mass% of solids) shown in Tables 9 and 10 with stirring using a disperser for a paint to prepare a coating composition Respectively.

In the preparation of the coating composition, 3-aminopropyltriethoxysilane (W1) and 3-glycidoxypropyltrimethoxysilane (W2) shown in Table 8 were mixed in a ratio [(W1) / (W2)], was added as an organic silicon compound (W) so as to have the contents shown in Tables 9 and 10.

(Paint stability)

The coating composition thus prepared was stirred at room temperature for 30 minutes, and the presence or absence of precipitates was visually observed.

The paint stability was evaluated as " OK " when no precipitate was formed, and the paint stability was evaluated as " NG " The results of the paint stability are shown in Tables 9 and 10.

As shown in Tables 9 and 10, the paint compositions used in Examples t1 to t14 and Comparative Examples w1 to w5 had a paint stability of "OK" and were excellent in stability.

Next, on each surface of the plated layer of the surface-treated steel sheet of Example V4 or Comparative Example x3 prepared in Example 1, the above-mentioned coating composition was used to form a film by the following method.

First, a coating composition was coated on the surface of the surface-treated steel sheet using a roll coater so as to have the thickness shown in Tables 11 and 12. Thereafter, the surface-treated steel sheet coated with the coating composition was heated and dried at a plate arrival temperature of 150 캜, and spray-cooled using water to obtain a coating film. Further, even after heating up to 150 캜, hydroxides were present in the plating layer.

Next, each of the surface-treated steel sheets on which the coating film was formed on the surface of the plating layer was evaluated for appearance uniformity, corrosion resistance, conductivity, workability and scratch resistance. In addition, as the reference example e2, the appearance uniformity, corrosion resistance, conductivity, workability, and scratch resistance of the surface-treated steel sheet of Example V4 prepared in Example 1 were evaluated.

The evaluation results of the respective items are shown in Tables 11 and 12.

Evaluation methods and evaluation criteria of each item are shown below.

(Appearance uniformity)

The L * value of the surface-treated steel sheet was measured using CR-400, manufactured by Konica Minolta Co., Ltd., and evaluated according to the following evaluation criteria.

(Evaluation standard)

5: L * value less than 24

4: L * value is 24 or more, less than 27

3: L * value is 27 or more, less than 28

2: L * value is 28 or more, less than 30

1: L * value exceeds 30

(Corrosion resistance)

The edge and back of the test piece cut out from the surface treated steel sheet were tape-sealed and subjected to a salt water spray test (JIS Z2371). The white rust occurrence area ratio of the non-silicon portion after 240 hours was visually observed and evaluated according to the following criteria. The white rust occurrence area ratio is a percentage of the area of the white rust occurrence area with respect to the area of the observed area.

(Evaluation standard)

6: Less than 3% incidence of white rye

5: incidence of white rye greater than 3%, less than 10%

4: incidence of white rye more than 10%, less than 25%

3: incidence of white rye more than 25%, less than 50%

2: incidence of white rye greater than 50%, less than 75%

1: White chalk occurrence rate 75% or more

(Conductive)

The interlaminar resistance value (Ω · cm 2) was measured using a test piece cut out from the surface treated steel sheet by a measuring method specified in JIS C 2550, and the conductivity was evaluated according to the following criteria.

(Evaluation standard)

6: Interlayer resistance value is less than 1.0? 占 ㎠

5: Interlayer resistance value of 1.0? Cm2 or more, less than 1.5? 占 ㎠

4: Interlayer resistance value is 1.5? 占 ㎠ 2 or more, less than 2.0? 占 ㎠

3: Interlayer resistance value of 2.0? Cm2 or more, less than 2.5?? Cm2

2: Interlayer resistance value of 2.5? Cm2 or more, less than 3.0? 占 ㎠

1: Interlayer resistance value is 3.0? 占 ㎠ 2 or more

(Processing Adhesion)

A test piece cut out from the surface-treated steel sheet was subjected to 180-degree bending, and then tape peeling test was performed on the outer side of the bent portion. The appearance of the tape peeling portion was observed with a loupe magnification of 10 times and evaluated according to the following evaluation criteria. The bending process was carried out with a spacer of 0.5 mm in the atmosphere at 20 캜.

(Evaluation standard)

5: Peeling is not confirmed on the film

4: Peeling was confirmed in a very small part of the coating film (peeling area ≤ 2%)

3: Peeling was confirmed in some coating films (2% < peel area &lt; = 10%)

2: Peeling was confirmed on the film (10% < peel area &lt; 20%)

1: Peeling was confirmed on the film (peeling area> 20%)

(Scratch resistance)

The specimen cut out from the surface-treated steel sheet was brought into close contact with the electro-galvanized steel sheet (untreated material), and the specimen was rotated by 90 ° under pressure. The pressure was 0.2 kg / cm 2, and the test temperature was 25 ° C. Thereafter, the appearance of the sealant was visually evaluated.

(Evaluation standard)

6: No scratches visible at all

5: Fine scratches, but no exposure of substrate

4: slight exposure of the substrate (exposure area: less than 3%)

3: Exposure of the substrate (exposure area: 3% or more, less than 10%)

2: exposure of the substrate (exposure area: 10% or more, less than 30%)

1: Exposure of the substrate (exposure area: 30% or more)

As shown in Tables 11 and 12, in Examples t1 to t14 having coatings on the surface of the plating layer of the surface-treated steel sheet of Example V4, evaluation results were not less than 2 as evaluation criteria, Uniformity, corrosion resistance, conductivity, workability and scratch resistance. In Examples t1 to t14, corrosion resistance and conductivity were good as compared with Reference Example e2 in which no film was formed on the surface.

On the other hand, Comparative Examples w1 to w5 having a coating on the surface of the plated layer of the surface-treated steel sheet of Comparative Example x3 had an evaluation result of appearance uniformity, corrosion resistance after 240 hours, adhesion to work and scratch resistance.

Example  3

&Quot; Test results of surface treated steel sheets containing zirconium &quot;

Using the plating apparatus shown in Fig. 2, a surface-treated steel sheet having a plated layer containing zirconium on both surfaces of the steel sheet was produced and evaluated by the following method.

The description of the same components as those of the first embodiment will be omitted.

A plating bath in a flowing state was prepared by circulating the plating bath composition, temperature and pH shown in Table 13 at an average relative flow rate of 100 m / min.

Then, pretreatment (nickel plating) was performed, and a steel sheet was used as a negative electrode. In the ground forming step and the upper layer plating step, the plating time was set to a time shown in Tables 14 and 15, and the current density was set to a numerical value shown in Tables 14 and 15, and a plating layer was formed by an electroplating method.

In the plating bath composition shown in Table 13, ZnSO ₄ .7H ₂ O was used as the Zn compound, ZrO (NO ₃ ) ₂ aqueous solution or ZrOSO ₄ aqueous solution was used as the Zr compound, and Na ₂ SO ₄ , NiSO ₄ .6H ₂ O as another metal compound was used. These contents were adjusted so that the concentrations of Zn ²⁺ , Zr (Zr ⁴⁺ , ZrO ²⁺ ), Na ⁺ , and Ni ²⁺ shown in Table 1 were obtained.

The plating layers of the thus-obtained examples and comparative examples were observed with a field emission transmission electron microscope (FE-TEM) (JED-2100F).

9 is a transmission electron microscope (TEM) photograph of the plating layer of the surface-treated steel sheet of Example Z4.

As shown in Fig. 9, it can be seen that in the plating layer of the present embodiment, the dendritic phase crystal, the intergranular charged region formed around the crystal, and the amorphous layer of the surface layer are formed. The dendrite phase crystals were found to be composed of metal Zn by elemental analysis and electron beam diffraction analysis by an energy dispersive X-ray analyzer (EDS (JED-2300T)). It has been found that the region includes zirconium oxide and zirconium hydroxide. It has also been found that the amorphous layer in the surface layer portion is made of zirconium oxide.

As in the case of Example Z4, the dendritic phase crystal, the intergranular charged region formed around the dendritic phase crystal, and the amorphous layer of the surface layer portion were formed in the plated layer of another embodiment. In addition, some amorphous layers in the surface layer were removed.

"Dendrite phase crystal", "intercrystalline charged region", "intergranular charged region", and "intergranular charged region" were obtained by using energy dispersive X-ray analyzer (EDS) (JED- 2300T) for each of the plating layers of Examples Z1 to Z20 &Quot; Surface layer of dendritic phase crystal &quot;. The elements (composition) included in the dendritic phase crystal, the elements (composition) included in the intergranular charged region, the zirconium amount and zinc amount thereof, and the elements (composition) included in the surface layer of the dendritic phase crystal were examined.

Further, the molar ratio (Zr / Zn) between the amount of zirconium and the amount of zinc in the intergranular filling region was calculated using the results of the elemental analysis.

In the plating layers of Comparative Examples x11 to x16, elemental analysis of "dendritic phase crystal", "intergranular filling region" and "surface layer of dendritic phase crystal" was carried out in the same manner as in Examples Z1 to Z20.

The results are shown in Tables 16 to 17.

It was confirmed that the dendritic phase crystal, the intergranular charged region and the surface layer of the dendritic phase crystal had a crystal structure or an amorphous phase, respectively, with respect to the plating layer of the surface-treated steel sheet of Examples Z1 to Z20. As a result, it was found that the surface layer of the dendritic phase crystal and the dendritic phase crystal had a crystal structure, and the intergranular charged region was amorphous.

Further, when impurities in the dendritic phase crystal were examined, C, Si, S, Fe, and N were each about 0.1 to 5 atm%.

The plating layers of the surface-treated steel sheets of Comparative Examples x11 to x16 were analyzed using an X-ray diffractometer (XRD: RINT2500 manufactured by Rigaku Corporation). As a result, it was confirmed that the dendritic phase crystal had the crystal structure of Zn with respect to the plating layers of Comparative Examples x11 to x16. In addition, it was confirmed that only an amorphous diffraction pattern which was unstable even when it was formed (Comparative Examples x11 to x14 and x16) was confirmed in the case where no intergranular filling region was formed (Comparative Example x15).

The following items were evaluated for the plating layers of Examples and Comparative Examples by the following methods.

(Deposition amount in the plating layer, zirconium content)

The deposition amount of the plated layer was determined as the total mass per unit area of Zn element and Zr element detected using a fluorescent X-ray apparatus (Simultix14 manufactured by Rigaku Corporation). The zirconium content in the plated layer was calculated as a percentage by dividing the amount of Zr element detected by the fluorescent X-ray apparatus by the deposition amount.

As shown in Table 18 and Table 19, all of Examples Z1 to Z20 satisfied the range of the present invention, and showed excellent barrier properties and coating film adhesion as compared with the surface treated steel sheets of Comparative Examples x11 to x16 I could.

In the plating layers of the surface-treated steel sheets of Examples Z1 to Z20 in which the current density in the ground formation step was 0 to 18 A / dm 2, the current density in the ground formation step was 25 A / dm 2, (Zr / Zn) of the zirconium and zinc in the intergranular filling region is 1.00 or more and 3.00 or less, and when the electron beam diffraction is carried out, the intergranular filling region is amorphous The diffraction pattern is shown. Further, it was found that the barrier property and the coating film adhesion were more excellent.

Example  4

&Quot; Test results of surface-treated zirconium-containing steel sheet &quot;

The coating composition for forming the coating film was prepared by mixing the organic resin (R), the phosphoric acid compound (P), the carbon black (C), the organic silicon compound (W), the fluoromethyl complex compound (F) (Isocyanate compound (I) and polyethylene wax (Q) were dispersed in water as a solvent with a dispersing machine for a coating agent in a content (mass% of solids) shown in Table 20 and Table 21 and dispersed to prepare a coating composition Respectively.

The description of the same components as those of the second embodiment will be omitted.

As shown in Tables 20 and 21, the coating compositions used in Examples u1 to u14 and Comparative Examples y1 to y5 had "OK" results of paint stability and excellent stability.

Next, the coating composition was applied to the surface of the plating layer of the surface-treated steel sheet of Example Z4 or Comparative Example x13 prepared in Example 3, respectively, to form a coating film by the following method.

First, on the surface of the surface-treated steel sheet, a coating composition was applied using a roll coater so as to have the thicknesses shown in Tables 22 and 23. Thereafter, the surface-treated steel sheet coated with the coating composition was heated and dried at a plate arrival temperature of 150 캜, and spray-cooled using water to obtain a coating film. Further, even after heating up to 150 캜, hydroxides were present in the plating layer.

Next, each of the surface-treated steel sheets on which the coating film was formed on the surface of the plating layer was evaluated for appearance uniformity, corrosion resistance, conductivity, workability and scratch resistance. As the reference example f1, the appearance uniformity, corrosion resistance, conductivity, workability and scratch resistance of the surface-treated steel sheet of Example Z4 prepared in (Example 3) were evaluated.

The evaluation results of the respective items are shown in Tables 22 and 23.

As shown in Tables 22 and 23, in Examples u1 to u14 having coatings on the surface of the plated layer of the surface-treated steel sheet of Example Z4, evaluation results were not less than 2 as evaluation criteria, Uniformity, corrosion resistance, conductivity, workability and scratch resistance. In Examples u1 to u14, corrosion resistance and conductivity were good, as compared with Reference Example f1 in which no film was formed on the surface.

On the other hand, Comparative Examples y1 to y5 having a coating on the surface of the coating layer of the surface-treated steel sheet of Comparative Example x13 had an evaluation result of appearance uniformity, corrosion resistance after 240 hours, adhesion to work and scratch resistance.

While the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these examples. It will be understood by those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention as defined by the appended claims.

According to each of the above-described embodiments, it is possible to provide a surface-treated steel sheet excellent in barrier property and coating film adhesion, in which a plating layer containing zinc and vanadium is formed on the surface of the steel sheet.

1, 201: steel plate
2: Plating bath
2a: piping for upper supply
2b: piping for lower supply
2c and 2e:
2d, 2f: intermediate branch
3: anode
3a: Inside of the dendritic phase crystal
3b, 55, 58: surface layer of dendritic phase crystal
3c: Granular crystals
4a, 5a, 4b, 5b: Roll
6: vanadium compound
10, 210: Surface treated steel sheet
20, 51, 220: ground layer
20a: Nickel plated layer
21: Plating tank
21a: upper tank
21b:
30, 230: Plated layer
31, 53, 56, 231: dendrite phase determination
32, 52, 54, 57, 232: inter-crystalline charging region
40, 240: surface layer
61: current-
62: hydrogen
250: amorphous layer
D: the distance between the rolls 4a, 5a and the anode 3

Claims (9)

Steel plate,
A plating layer formed on one surface or both surfaces of the steel sheet and containing zinc and vanadium or zirconium;
And,
Wherein,
A dendritic phase crystal including metallic zinc,
The dendritic phase crystal interlayer is filled, and when the electron beam diffraction is carried out, an intercrystalline charge region
Lt; / RTI &
Wherein when the plating layer contains vanadium, the intercrystalline fill region includes hydrated vanadium oxide or vanadium hydroxide,
Wherein when the plating layer contains zirconium, the intercrystalline fill region includes hydrated zirconium oxide or zirconium hydroxide
Wherein the surface-treated steel sheet is a surface-treated steel sheet. The method according to claim 1,
And a base layer made of crystals containing nickel is further formed between the steel sheet and the plating layer. 3. The method according to claim 1 or 2,
Wherein V / Zn, which is the molar ratio of vanadium and zinc in the inter-crystal charged region, is 0.10 or more and 2.00 or less when the plating layer contains vanadium,
Wherein a Zr / Zn molar ratio of said zirconium and said zinc in said intergranular filling region is 1.00 or more and 3.00 or less when said plating layer contains said zirconium. 4. The method according to any one of claims 1 to 3,
Wherein the plating layer includes the vanadium,
Wherein the surface layer of the dendritic phase crystal contains zinc oxide or zinc hydroxide. The method according to claim 1,
Wherein a lower plating layer having a Zn / V ratio of 8.00 or more, which is a molar ratio of zinc and vanadium, is further formed between the steel sheet and the plating layer. 3. The method of claim 2,
Wherein a base plating layer having a Zn / V ratio of 8.00 or more, which is a molar ratio of zinc and vanadium, is further formed between the base layer and the plating layer. 7. The method according to any one of claims 1 to 6,
Further comprising an organic resin film having a polyurethane resin and 1 to 20 mass% of carbon black on the surface of the plating layer. A method for producing a surface-treated steel sheet according to any one of claims 1 to 7,
Using a plating bath containing 0.10 to 4.00 mol / l of Zn ²⁺ ions, 0.01 to 2.00 mol / l of V ions or 0.10 to 4.00 mol / l of Zr ions, at an average flow rate of 40 to 200 m / min and A base forming step of depositing vanadium oxide or vanadium hydroxide hydrated on the steel sheet by electroplating at a current density of 0 to 18 A / dm &lt; 2 &gt; to form irregularities;
An upper layer plating step of performing electroplating at an average flow rate of 40 to 200 m / min and a current density of 21 to 200 A / dm &lt; 2 &gt; using the plating bath,
Treated steel sheet. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; 9. The method of claim 8,
Further comprising a step of depositing crystals containing nickel on the steel sheet by performing electroplating using a plating bath containing Ni ²⁺ ions before the ^ground formation step .

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