JPWO2016199852A1 - Surface-treated steel sheet - Google Patents

Abstract

The surface-treated steel sheet comprises: a steel sheet; and a plating layer formed on one or both surfaces of the steel sheet and containing zinc and vanadium or zirconium; and the plating layer includes a dendrite-like crystal containing metallic zinc; An intercrystalline packing region that exhibits an amorphous diffraction pattern when the space between the crystalline crystals is filled and electron beam diffraction is performed, and when the plating layer contains the vanadium, In the case where hydrated vanadium oxide or vanadium hydroxide is included, and the plating layer includes zirconium, the intercrystalline filling region includes hydrated zirconium oxide or zirconium hydroxide.

Description

The present invention relates to a surface-treated steel sheet having excellent corrosion resistance (barrier property) and coating film adhesion in plating in a corrosive environment.
This application claims priority on June 9, 2015 based on Japanese Patent Application No. 2015-116554 and Japanese Patent Application No. 2015-116604 for which it applied to Japan, and uses the content here.

Conventionally, electrogalvanized steel sheets have been used in various fields such as home appliances, building materials and automobiles. Electrogalvanized steel sheets are required to further improve the corrosion resistance and corrosion resistance (hereinafter referred to as barrier properties) of plating in corrosive environments.
As a method for improving the barrier property of the electrogalvanized steel sheet, it is conceivable to increase the plating amount (weight per unit area) of the galvanized layer. However, when the basis weight of the galvanized layer is increased, there is a problem that the manufacturing cost increases and the workability and weldability are lowered.

  Further, as a method for improving the barrier property and appearance of the electrogalvanized steel sheet, a technique for forming a coating film on the surface has been widely used. However, if the adhesion between the electrogalvanized steel sheet and the coating layer (coating film adhesion) is insufficient, even if a coating film is formed on the surface, the effect of forming the coating film is sufficient. I can't get it. For this reason, while improving the barrier property of an electrogalvanized steel plate, improving a coating-film adhesiveness is requested | required.

In recent years, it has been studied to improve barrier properties by adding a vanadium element to a galvanized layer of an electrogalvanized steel sheet. For example, Non-Patent Documents 1 to 4 describe a technique in which Zn-V oxide is compositely deposited on the surface of a copper plate as a cathode.
Patent Document 1 describes a technique for forming a V-concentrated layer in the surface layer portion of a plated layer of a zinc-based plated steel sheet.
Patent Document 2 describes a technique related to a plating layer containing zinc and vanadium and having a plurality of dendritic arms.

  Patent Document 3 describes that a plated layer containing zinc and vanadium formed on a steel sheet has a dendrite-like crystal in which vanadium oxide is present in zinc. It is described that there is a phase having a higher vanadium content than in the dendritic crystals.

  Patent Document 4 describes that in a zinc-based composite electroplated steel sheet containing zinc and vanadium hydroxide, vanadium hydroxide is co-deposited in zinc.

Japanese Unexamined Patent Publication No. 2013-185199 Japanese Patent No. 5273316 Japanese Unexamined Patent Publication No. 2013-108183 Japanese Unexamined Patent Publication No. 2011-111633

CAMP-ISIJ Vol. 22 (2009) -933-936 Iron and steel Vol. 93 (2007) No. 11, pages 49-54 Surface Technology Association 115th Annual Meeting Abstract, 9A-26, 139-140 Ferrum Vol.13, No. 4, 245 pages, 2008.4.1.

However, the conventional surface-treated steel sheet having a plated layer containing zinc and vanadium on the surface of the steel sheet is required to further improve the barrier property.
Further, since V (vanadium) is a rare element, plating having excellent barrier properties in place of zinc vanadium plating is desired.
The present invention has been made in view of such circumstances, and is a surface treatment excellent in barrier properties and coating film adhesion in which a plating layer containing zinc and vanadium or zirconium is formed on the surface of a steel plate. It is an object to provide a steel plate.

In order to solve the above problems, the present inventor has intensively studied as described below.
That is, the present inventor formed a plating layer containing zinc and vanadium or zirconium on the surface of the steel sheet under various conditions using the steel sheet as a cathode by an electroplating method, and investigated its barrier properties and coating film adhesion. .

As a result, the present inventor is a plating layer containing zinc and vanadium, which has a dendrite-like crystal containing metallic zinc and an intercrystalline filling region containing hydrated vanadium oxide or vanadium hydroxide. It has been found that a layer may be formed. Since such a plated layer has an intercrystalline filling region containing hydrated vanadium oxide or vanadium hydroxide, for example, than a plated steel sheet in which a galvanized layer is provided instead of this plated layer. The corrosion potential is noble and has excellent barrier properties.
Further, the present inventor has found that a phase containing hydrated zirconia oxide or zirconia hydroxide is formed around a dendrite-like crystal composed of metallic zinc under certain conditions. Such a plating layer was found to have a barrier property equal to or higher than that of zinc vanadium plating and excellent in coating film adhesion, thereby completing the present invention. Each aspect of the present invention is as follows.

(1) A surface-treated steel sheet according to an aspect of the present invention comprises: a steel sheet; and a plating layer formed on one or both surfaces of the steel sheet and containing zinc and vanadium or zirconium. A dendrite-like crystal containing; and an inter-crystal filling region that fills the space between the dendrite-like crystals and exhibits an amorphous diffraction pattern when electron diffraction is performed, and the plating layer contains the vanadium. In the case where the intercrystalline filling region contains hydrated vanadium oxide or vanadium hydroxide, and the plating layer contains zirconium, the intercrystalline filling region becomes hydrated zirconium oxide or zirconium water. Contains oxides.
(2) In the surface-treated steel sheet according to the above (1), when the plating layer contains the vanadium, V / Zn that is a molar ratio of the vanadium and the zinc in the intercrystalline filling region is 0. Zr / Zn, which is the molar ratio of the zirconium and the zinc in the intercrystalline filling region, is 1.00 or more and 3.000 or less and 2.00 or less and the plating layer contains the zirconium. You may employ | adopt the structure which is 00 or less.
(3) In the surface-treated steel sheet according to (1) or (2) above, the plating layer includes the vanadium, and the surface layer of the dendritic crystal includes zinc oxide or zinc hydroxide. A configuration may be adopted.

(4) In the surface-treated steel sheet according to any one of (1) to (3), Zn / V, which is a molar ratio of zinc and vanadium, is 8 between the steel sheet and the plating layer. A configuration in which a base plating layer of 0.000 or more is further provided may be employed.
(5) In the surface-treated steel sheet according to any one of (1) to (4), an organic resin film having a polyurethane resin and 1 to 20% by mass of carbon black is formed on the surface of the plating layer. Furthermore, you may employ | adopt the structure provided.
(6) The manufacturing method of the surface-treated steel sheet which concerns on 1 aspect of this invention is a method of manufacturing the surface-treated steel sheet as described in any one of said (1)-(5), Comprising: 0.10-4 0 to 18 A / dm using a plating bath containing 0.000 mol / l Zn ²⁺ ions and 0.01 to 2.00 mol / l V ions or 0.10 to 4.00 mol / l Zr ions. By performing electroplating at a current density of ² to deposit hydrated vanadium oxide or vanadium hydroxide on the steel sheet to form irregularities; and to form the irregularities on the steel sheet, And an upper layer plating step of performing electroplating at a current density of 21 to 200 A / dm ² using the plating bath.

  According to each said aspect, the surface-treated steel plate which has the outstanding barrier property and coating-film adhesiveness can be provided.

It is a cross-sectional schematic diagram for demonstrating an example of the surface treatment steel plate which concerns on 1st Embodiment. It is a cross-sectional schematic diagram for demonstrating an example of the surface treatment steel plate which concerns on 2nd Embodiment. It is the schematic which showed an example of the plating apparatus used when manufacturing the surface treatment steel plate which concerns on this embodiment. It is a schematic diagram for demonstrating precipitation of the vanadium compound in the process of manufacturing the surface treatment steel plate shown in FIG. It is a schematic diagram for demonstrating the growth of the dendrite-like crystal | crystallization in the process of manufacturing the surface treatment steel plate shown in FIG. It is a schematic diagram for demonstrating generation | occurrence | production of the hydrogen in the front-end | tip of the branch part of a dendrite-like crystal | crystallization in the process of manufacturing the surface treatment steel plate shown in FIG. It is a cross-sectional photograph of the whole thickness direction by the transmission electron microscope (TEM) of the plating layer of the surface treatment steel plate of Example V4. It is an enlarged photograph of the interface part of the steel plate and plating layer in the section of Drawing 5A. It is an enlarged photograph of the dendrite-like crystal in the cross section of FIG. 5A and its peripheral part. It is a scanning electron microscope (SEM) photograph of the plating layer of the surface treatment steel plate of Example V4. It is a scanning electron microscope (SEM) photograph of the plating layer of the surface treatment steel plate of comparative example x2. It is the photograph which showed the electron beam diffraction image of the plating layer of the surface treatment steel plate of Example V4. It is a transmission electron microscope (TEM) photograph of the plating layer of the surface-treated steel sheet of Example Z4.

"First embodiment, surface-treated steel sheet 10"
Hereinafter, the surface-treated steel sheet 10 according to the first embodiment when the plating layer contains vanadium will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view for explaining an example of the surface-treated steel sheet 10 according to the present embodiment. A surface-treated steel sheet 10 shown in FIG. 1 has a base layer 20, a plating layer 30, and a surface layer 40 formed in order from the steel sheet 1 side on both surfaces of the steel sheet 1, respectively. In FIG. 1, only the base layer 20, the plating layer 30, and the surface layer 40 formed on one surface (upper surface) side of the steel plate 1 are illustrated, and the description on the other surface (lower surface) side is omitted.

  In this embodiment, it does not specifically limit as the steel plate 1 in which the plating layer 30 is formed in the surface. For example, as the steel sheet 1, an extremely low C type (ferrite main structure), Al-k type (structure containing pearlite in ferrite), two-phase structure type (for example, structure containing martensite in ferrite, bainite in ferrite) Any type of steel sheet may be used, such as a processing induced transformation type (structure containing residual austenite in ferrite), a fine crystal type (ferrite main structure), and the like.

  As shown in FIG. 1, an underlayer 20 may be provided between the steel plate 1 and the plating layer 30. The underlayer 20 is provided as necessary in order to improve the adhesion between the steel plate 1 and the plating layer 30. In the present embodiment, it is preferable that an underlayer 20 having a thickness of 1 to 300 nm and made of a crystal containing nickel is provided.

As shown in FIG. 1, the plating layer 30 includes a dendrite-like crystal 31 and an inter-crystal filling region 32 which is disposed between the dendrite-like crystals 31 and exhibits an amorphous diffraction pattern when electron beam diffraction is performed. Have.
In the present invention, “amorphous” means that a diffraction pattern resulting from the crystal structure cannot be obtained by performing electron beam diffraction for each layer from the cross-sectional direction using a transmission electron microscope (TEM).

The intercrystalline filling region 32 includes hydrated vanadium oxide or vanadium hydroxide. The intercrystalline filling region 32 preferably contains vanadium hydroxide in order to improve the coating film adhesion.
Moreover, it is preferable that the intercrystal filling area | region 32 contains zinc. Corrosion resistance is improved by the intercrystalline filling region 32 containing zinc.

  When the intercrystalline filling region 32 includes hydrated vanadium oxide or vanadium hydroxide and zinc, the molar ratio (V / Zn) of vanadium and zinc in the intercrystalline filling region 32 is 0.10 or more. It is preferable that it is 2.00 or less. The above molar ratio (V / Zn) is in the above range, and when the electron beam diffraction is performed, the intercrystalline filling region shows an amorphous diffraction pattern, so that excellent corrosion resistance (barrier property) and coating are achieved. Film adhesion is obtained. If the molar ratio (V / Zn) of vanadium and zinc in the inter-crystal filling region 32 is less than 0.10, an amorphous diffraction pattern may not be stably obtained, and the corrosion resistance is inferior. On the other hand, when the molar ratio exceeds 2.00, the sacrificial corrosion resistance of the plating deteriorates.

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

  In the surface-treated steel sheet 10 of the present embodiment, as shown in FIG. 1, each dendrite-like crystal 31 has an interior 3 a of the dendrite-like crystal and a surface layer 3 b formed on the surface of the dendrite-like crystal 31. . The inside 3a of the dendritic crystal 31 is grown from the steel plate 1 side toward the outside and has a plurality of branched portions. The surface layer 3b is formed with a substantially uniform thickness so as to cover the surface of the inside 3a of the dendritic crystal 31.

  The dendrite-like crystal 31 shown in FIG. 1 having the interior 3a and the surface layer 3b of the dendrite-like crystal 31 has a maximum length of 4.0 μm or less and a maximum width of 0.5 μm or less when viewed in cross section. Is preferred. When the maximum length and the maximum width of the dendrite-like crystal 31 are within the above ranges, the dense plating layer 30 having the fine dendrite-like crystal 31 is obtained. For this reason, the barrier effect | action of the plating layer 30 improves, and the further outstanding barrier property is obtained. In order to further improve the barrier property, the maximum length of the dendritic crystal 31 is more preferably 3.0 μm or less. The maximum width of the dendrite-like crystal 31 when viewed in cross section is more preferably 0.4 μm or less.

In the present embodiment, “the maximum length of the dendrite-like crystal 31” means that the cross section of the plating layer is observed using a scanning electron microscope (SEM), and the maximum length of the 50 dendrite-like crystals 31 is measured. This is obtained by calculating the average value.
Further, “the maximum width when the cross-section of the dendrite-like crystal 31 is viewed” means that the cross-section of the plating layer is observed using a transmission electron microscope (TEM), and the maximum width of the 50 dendrite-like crystals 31 is measured. This is obtained by calculating the average value.

The interior 3a of the dendritic crystal 31 preferably contains metallic zinc. The interior 3a of the dendritic crystal 31 may contain other metal components such as nickel, which is nobler than the deposition potential of zinc, in addition to zinc metal.
Moreover, it is preferable that the surface layer 3b contains the crystal | crystallization containing a zinc oxide or a zinc hydroxide. More preferably, the surface layer 3b includes zinc oxide crystals. The thickness of the surface layer 3b is preferably 0.1 to 500 nm.

  In addition, as shown in FIG. 1, granular crystals 3 c may be included in the interior 3 a of the dendritic crystals 31. The granular crystal 3c contains zinc and nickel. The particle size of the granular crystals 3c is preferably 0.1 to 500 nm. When the particle size of the granular crystals 3c is within the above range, more excellent coating film adhesion can be obtained.

  In the surface-treated steel sheet 10 of this 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. It is preferable that Zn / V is 0.50 or more and less than 8.00 because an excellent barrier function due to the inclusion of vanadium can be obtained.

In the surface-treated steel sheet 10, a base plating layer containing zinc (non-coated) is present between the steel sheet 1 and the plating layer 30 (between the base layer 20 and the plating layer 30 when the base layer 20 is formed). (Illustrated) may be formed. This is because the formation of a base plating layer (not shown) provides an excellent effect of improving the corrosion resistance by sacrificial corrosion prevention of zinc.
The undercoat layer (not shown) may contain zinc and vanadium and may have a Zn / V molar ratio of the zinc to the vanadium of 8.00 or more. Moreover, the base plating layer (not shown) may be comprised only from zinc.

An upper plating layer (not shown) containing zinc may be formed on the upper layer of the plating layer 30. The formation of an upper plating layer (not shown) is preferable because an excellent effect of improving corrosion resistance by sacrificial corrosion prevention of zinc can be obtained.
The upper plating layer (not shown) may be composed only of zinc. Further, the upper plating layer (not shown) may contain zinc and vanadium, and Zn / V that is a molar ratio of the zinc to the vanadium may be 8.00 or more.

By controlling the current density of electroplating and adjusting the molar ratio of zinc and vanadium, between the steel plate 1 and the plating layer 30 (when the underlayer 20 is formed, the underlayer 20 and the plating layer 30 A base plating layer (not shown) can be formed between the two.
An upper plating layer (not shown) can be formed on the plating layer 30 by the same method as that for the base plating layer (not shown).

Molar ratio (a / b) between the amount of zinc (a) contained in the interior 3a of the dendritic crystal 31 and the total amount (b) of zinc contained in the intercrystalline filling region 32 and the surface layer 3b of the dendritic crystal 31 Is preferably in the range of 0.10 to 3.00.
When the above molar ratio (a / b) is 0.10 or more, the sacrificial anticorrosive action by the metallic zinc contained in the dendritic crystal 31 is effectively obtained when the surface of the plating layer 30 is damaged. And better barrier properties can be obtained. In order to more effectively obtain the sacrificial anticorrosive action by the metallic zinc contained in the dendritic crystal 31, it is more preferable that the molar ratio (a / b) is 0.20 or more.
Moreover, when said molar ratio (a / b) is 3.00 or less, the steel plate 1 resulting from the zinc oxide or zinc hydroxide contained in the surface layer of the dendrite-like crystal 31 being difficult to let air and water pass through. The effect of improving the barrier property 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 crystal 31, the molar ratio (a / b) is more preferably 0.25 or less.

Further, the molar ratio of the total amount (A) of the zinc amount contained in the dendrite-like crystal 31 and the zinc amount contained in the surface layer 3b of the dendrite-like crystal 31 to the vanadium amount (B) contained in the intercrystal filling region 32 ( A / B) is preferably 0.05 or more and 6.00 or less. When the above molar ratio (A / B) is 0.05 or more, sacrificial anticorrosive action by metallic zinc contained in the dendritic crystal 31 and zinc oxide or zinc hydroxide contained in the surface layer 3b of the dendritic crystal 31. The effect of improving the barrier property by the object can be obtained effectively, and a better barrier property can be obtained.
In order to more effectively obtain the sacrificial anticorrosive action by the dendritic crystal 31 and the barrier property improving action by the surface layer 3b of the dendritic crystal 31, the molar ratio (A / B) may be 0.10 or more. More preferred. Moreover, when said molar ratio (A / B) is 6.00 or less, the effect of making the corrosion potential noble by containing vanadium noble and improving barrier property is exhibited more effectively. In order to further improve the barrier property improving effect by containing vanadium, the molar ratio (A / B) is more preferably 5.00 or less, and further preferably 4.50 or less.

In the present embodiment, the vanadium content 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 properties can be obtained. The vanadium content in the plating layer 30 is more preferably 4% by mass or more in order to further improve the barrier property and the coating film adhesion. When the vanadium content in the plating layer 30 is 20% by mass or less, the content of the dendritic crystal 31 and the surface layer 3b of the dendritic crystal 31 is relatively increased, and the sacrificial anticorrosive action by the dendritic crystal 31 and the dendritic shape are increased. The effect of improving the barrier property by the surface layer 3b of the crystal 31 is effectively obtained.
The vanadium content of the plating layer 30 is more preferably 15% by mass or less in order to secure the content of the dendritic crystals 31 and the surface layer 3b of the dendritic crystals 31.

The adhesion amount of the plating layer 30 is preferably 1 g / m ² or more, and more preferably 3 g / m ² or more in order to improve the barrier property. The adhesion amount of the plating layer 30 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 adhesion amount of the plating layer 30 is 15 g / m ² or less, the amount of metal to be deposited can be reduced as compared with the conventional electrogalvanizing (usually about 20 g / m ² ). It is economically superior from the viewpoint of metal cost and electric power cost for forming.

  The surface-treated steel sheet 10 of this embodiment preferably has a natural immersion potential (corrosion potential) of −0.8 V or more when immersed in a 5% NaCl aqueous solution at 25 ° C. using the plating layer 30 as a working electrode. The corrosion potential is preferably higher (noble) by 0.2 V or more than a plated steel sheet (corrosion potential of about −1.0 V) provided with a galvanized layer instead of the plated layer 30. In order to further improve the barrier property, the corrosion potential is more preferably −0.7 V or more.

As shown in FIG. 1, a surface layer 40 composed of one or more layers is formed on the surface of the plating layer 30. The surface layer 40 is provided as necessary. By forming the surface layer 40, the corrosion resistance is improved.
The one or more layers forming the surface layer 40 preferably contain an organic resin (R).

It does not specifically limit as organic resin (R) contained in a membrane | film | coat, For example, a polyurethane resin can be mentioned.
As the organic resin (R) contained in the film, one or more organic resins (non-modified) may be mixed and used, or in the presence of at least one organic resin, One or two or more organic resins obtained by modifying one type of other organic resin may be used.

Examples of the polyurethane resin used for the organic resin (R) include those obtained by reacting a polyol compound and a polyisocyanate compound and then chain-extending with 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. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol , Neopentyl glycol, triethylene glycol, glycerin, trimethylol ethane, trimethylol propane, polycarbonate polyol, polyester polyol, polyether polyol such as bisphenol hydroxypropyl ether, polyester amide polyol, acrylic polyol, polyurethane polyol, or a mixture thereof. Can be mentioned.

  As the polyisocyanate compound used as a raw material of the polyurethane resin, a compound containing two or more isocyanate groups per molecule is used. For example, aliphatic isocyanate such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) And alicyclic diisocyanates such as tolylene diisocyanate (TDI), araliphatic diisocyanates such as diphenylmethane diisocyanate (MDI), and mixtures thereof.

  As the chain extender used in producing the polyurethane resin, a compound containing one or more active hydrogens in the molecule is used, for example, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, Aliphatic polyamines such as triethylenetetramine and tetraethylenepentamine, aromatic polyamines such as tolylenediamine, xylylenediamine and diaminodiphenylmethane, and fats such as diaminocyclohexylmethane, piperazine, 2,5-dimethylpiperazine and isophoronediamine Cyclic polyamines, hydrazines such as hydrazine, succinic dihydrazide, adipic dihydrazide, phthalic dihydrazide, hydroxyethyldiethylenetriamine, 2-[(2-aminoethyl) a Bruno] ethanol, alkanolamines such as 3-amino-propanediol. These compounds used as chain extenders can be used alone or in admixture of two or more.

The polyurethane resin used for the organic resin (R) is a polyol compound contained in the regenerated isocyanate group and the raw material solution by heating the raw material solution containing the blocked isocyanate compound and the polyol compound to a temperature at which the blocking agent is dissociated. It may be obtained by reacting with a polyol component.
The blocked isocyanate compound regenerates the isocyanate group by heating to a temperature above the dissociation temperature of the blocking agent. As a block isocyanate compound, what masked the isocyanate group of the said polyisocyanate compound with the conventionally well-known blocking agent can be used, for example. As the blocking agent, for example, dimethylpyrazole (DMP), methyl ethyl ketone oxime and the like can be used.

  In addition to the organic resin (R), one or more films forming the surface layer 40 are composed of a phosphoric acid compound (P), an organic silicon compound (W), carbon black (C), and a fluorometal complex compound ( It is preferable that 1 type, or 2 or more types of raw materials chosen from F) and polyethylene wax (Q) are included.

  The phosphate compound (P) contained in the film is more preferably a compound that releases phosphate ions in the film. When the phosphoric acid compound (P) is a compound (P) that releases phosphate ions in the film, the film is formed when the coating composition for forming the film is in contact with the plating layer 30 or after the film is formed. When the phosphate ion derived from the phosphate compound is eluted from the surface, the phosphate compound (P) reacts with the vanadium oxide present on the surface of the plating layer 30 to form a phosphoric acid- A vanadium-based film is formed. Thereby, white rust resistance can be improved significantly.

  When the phosphate compound (P) is a non-soluble substance that does not release phosphate ions in the environment, the phosphate compound (P) contained in the coating inhibits the transfer of corrosion factors such as water and oxygen. Therefore, excellent barrier properties can be obtained.

  Examples of the phosphoric acid compound (P) contained in the film include phosphoric acids such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, and ammonium dihydrogen phosphate. it can. 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% by mass as phosphate ions, more preferably 6 to 18% by mass, and most preferably 10 to 15% by mass. Excellent barrier properties are obtained when the concentration of phosphate ions contained in the film is 1% by mass or more. Further, when the phosphate ion concentration in the film is 20% by mass or less, the swelling of the coating film due to elution of phosphoric acid can be prevented.

  When the phosphoric acid compound (P) is contained in the film, the surface of the steel plate 1 contains vanadium in the plating layer 30 and the phosphoric acid compound in the film, and is excellent for corrosion factors (such as water and oxygen). A barrier layer (not shown) having a barrier property is formed. As a result, compared with the case where the surface layer 40 is not formed on the surface of the plating layer 30, the effect of delaying the occurrence of red rust is obtained while being excellent in white rust resistance, and the barrier property is remarkably improved.

Examples of the organosilicon compound (W) contained in the film include hydrolysis condensates of silane coupling agents.
As a silane coupling agent used for the production | generation of the organosilicon compound (W) in a film | membrane, 3-glycidoxy propyl trimethoxysilane 3-aminopropyl triethoxysilane can be mentioned, for example. The said silane coupling agent may be used independently and may use 2 or more types together.

  The organosilicon compound (W) in the film is preferably 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, the reaction is caused by the reaction between the amino group and the epoxy group, and the reaction between the alkoxysilyl group contained in each of the silane coupling agent (W1) and the silane coupling agent (W2) or partial hydrolysis products thereof. A dense film with high density is formed. As a result, the barrier property, scratch resistance, and contamination resistance of the surface-treated steel sheet are further improved.

  Examples of the amino group-containing silane coupling agent (W1) include 3-aminopropyltriethoxysilane. Examples of the silane coupling agent (W2) containing an epoxy group include 3-glycidoxypropyltrimethoxysilane.

  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 0.5 or more and 2.5 or less. Is more preferable, and is 0.7 or more and 1.6 or less. When the molar ratio [(W1) / (W2)] is 0.5 or more, a sufficient film-forming property is obtained, so that the barrier property is improved. Moreover, since sufficient water resistance is obtained as said molar ratio is 2.5 or less, the outstanding barrier property is obtained.

  The organosilicon compound (W) contained in the film preferably has, for example, a number average molecular weight of 1,000 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 film having excellent water resistance is obtained, and alkali resistance and barrier properties 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 is improved. May decrease.

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

  The mass ratio (R / W) between the organic resin (R) and the organosilicon compound (W) in the film is preferably 1.0 to 3.0. When R / W is 1.0 or more, cohesive failure hardly occurs in the film during processing, and processing adhesion is improved. Moreover, the effect by containing an organosilicon compound (W) is fully acquired as R / W is 3.0 or less, and the film | membrane with high hardness is obtained.

  The organosilicon compound (W) can be produced, for example, by a method in which the silane coupling agent described above is dissolved or dispersed in water and stirred at a predetermined temperature for a predetermined time to obtain a hydrolysis condensate.

The coating containing the organosilicon compound (W) is prepared, for example, by producing an aqueous liquid or alcohol-based liquid containing the organosilicon compound (W) as a raw material for the coating composition for forming the coating, and including the coating composition. Can be formed on the plating layer and dried.
The aqueous liquid or alcohol-based liquid containing the organosilicon compound (W) is, for example, a method for obtaining an aqueous liquid by dissolving or dispersing an organosilicon compound such as a hydrolysis condensate of a silane coupling agent in water, a silane cup It can be produced by a method in which an organosilicon compound such as a hydrolyzed condensate of a ring agent is dissolved in an alcoholic organic solvent such as methanol, ethanol or isopropanol to obtain an alcoholic liquid.

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

  The solid content concentration of the organosilicon compound (W) in the aqueous liquid or alcohol-based liquid of the organosilicon compound (W) is preferably 25% by mass or less. When the solid content concentration of the organosilicon compound (W) is 25% by mass or less, the storage stability of the aqueous liquid or alcohol-based liquid is improved.

  The film preferably contains carbon black (C) as a coloring pigment. When carbon black is contained in the film, fine unevenness existing on the surface of the plating layer is concealed, and a beautiful black appearance is obtained, and excellent design is obtained.

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

  The particle size of the carbon black (C) contained in the film is not particularly limited as long as there is no problem in the dispersibility in the coating composition for film formation, the quality of the coating film, and the coating property. When carbon black is dispersed in an aqueous solvent, it aggregates in the process of dispersion. For this reason, in general, it is difficult to disperse carbon black in an aqueous solvent while maintaining the primary particle size. Therefore, the carbon black contained in the coating composition for film formation exists in the form of secondary particles having a particle size larger than the primary particle size. Therefore, the carbon black in the film formed using the coating composition is also present in the form of secondary particles as in the coating composition.

As carbon black used as a raw material of the film, for example, one having a primary particle diameter of 10 nm to 120 nm can be used. In consideration of the design and barrier properties of the film, the particle size of carbon black contained in the film is preferably 10 nm to 50 nm.
In order to ensure the design and barrier properties of the coating, the particle size of the carbon black in the form of secondary particles dispersed in the coating is important. The average particle size of carbon black in the film is preferably 20 nm to 300 nm.

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

  A fluoro metal complex compound (F) can be contained in the film. The fluoro metal complex compound (F) acts as a crosslinking agent in the film and improves the cohesive strength of the film. The fluoro metal complex compound (F) is not particularly limited, but it is preferable to use a fluoro metal complex compound containing titanium from the viewpoint of barrier properties. An example of such a fluorometal complex compound (F) is titanium hydrofluoric acid.

  The film may contain polyethylene wax (Q). Polyethylene wax (Q) can improve the scratch resistance of the film. Therefore, when polyethylene wax (Q) is contained in the film, the lubricity of the surface-treated steel sheet is increased, for example, the frictional resistance due to the contact between the steel sheet and the press die is reduced, and the damage in the processed part of the steel sheet is reduced. And it is possible to prevent scratches when handling steel sheets.

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

  The polyolefin resin-based lubricant used as the polyethylene wax (Q) is not particularly limited, and examples thereof include hydrocarbon waxes such as polyethylene.

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

"Production method of surface-treated steel sheet 10"
Next, the manufacturing method of the surface treatment steel plate 10 is demonstrated.
The manufacturing method of the surface treatment steel plate of this embodiment is 0.10 to 4.00 mol / l Zn ²⁺ ion and 0.01 to 2.00 mol / l V ion or 0.10 to 4.00 mol / l. By performing electroplating at a current density of 0 to 18 A / dm ² using a plating bath containing Zr ions, hydrated vanadium oxide or vanadium hydroxide is deposited on the steel sheet 1 to form irregularities. And an upper layer plating step in which electroplating is performed on the steel plate 1 having the irregularities formed thereon with a current density of 21 to 200 A / dm ² using the plating bath. The underlayer forming process described above is one factor that affects the V / Zn that is the molar ratio of the vanadium and the zinc in the intercrystalline filling region in the plating layer. When the current density in the underlayer forming process exceeds 18 A / dm ² , V / Zn, which is the molar ratio of vanadium and zinc in the intercrystal filling region, is less than 0.10.

In the present embodiment, pretreatment is performed on both surfaces of the steel plate 1 forming the plating layer 30 as necessary. As the pretreatment, it is preferable to form a base layer 20 by performing nickel plating with a thickness of 1 to 300 nm on both surfaces of the steel plate 1.
Next, the plating layer 30 is formed on one side or both sides of the steel plate 1. In the present embodiment, a method of forming the plating layers 30 on both surfaces of the steel plate 1 by electroplating using the plating apparatus shown in FIG. 3 will be described as an example.

  FIG. 3 is a schematic view showing an example of a plating apparatus. In the present embodiment, among the rolls 4a, 4b, 5a, and 5b, the rolls 4a and 4b arranged on the upper part of the steel plate 1 are connection members (conductors) that electrically connect a power source (not shown) and the steel plate 1. ). The steel plate 1 is made into a cathode by being electrically connected to the rolls 4a and 4b. When performing electroplating, a plurality of plating apparatuses shown in FIG. 3 are used in series. The base formation step is performed in a region surrounded by the plating apparatus shown in FIG. 3 or the rolls 4a and 5a and the intermediate branch paths 2d and 2f in FIG. Further, the upper layer plating step is performed in a region surrounded by the plating apparatus shown in FIG. 3 or intermediate branch paths 2d and 2f and rolls 4b and 5b in FIG.

The plating tank 21 has an upper tank 21 a disposed at the upper part of the steel plate 1 and a lower tank 21 b disposed at the lower part of the steel plate 1.
As shown in FIG. 3, a plurality of anodes 3 made of platinum or the like are disposed at a predetermined interval between the steel plates 1 at positions adjacent to the steel plates 1 in the upper tank 21 a and the lower tank 21 b. Yes. The surface of each anode 3 facing the steel plate 1 is arranged so as to be substantially parallel to the surface of the steel plate 1. Each anode 3 is electrically connected to a power source (not shown) by a connecting member (not shown).

  The inside of the upper tank 21 a and the lower tank 21 b are filled with the plating bath 2. As shown in FIG. 3, between the upper tank 21 a and the lower tank 21 b of the plating tank 21, the steel plate 1 that moves with the surface direction being substantially horizontal is disposed. And the steel plate 1 which has passed through the inside of the plating tank 21 in the direction of the arrow by the rolls 4a, 4b, 5a, 5b is in a state immersed in the plating bath 2 in the upper tank 21a and the lower tank 21b. . Therefore, in this embodiment, the steel plate 1 is conveyed by the rolls 4a, 4b, 5a, and 5b, and the steel plate 1 is moved in the plating bath 2, so that the plating bath 2 flows relatively to the steel plate 1. The fluidized plating bath 2 is formed.

  As shown in FIG. 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 penetrate 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 paths 2d are arranged along the width direction of the steel sheet 1 between the anodes 3 adjacent in a plan view. The intermediate branch 2 d includes an opening for supplying the plating bath 2 between the anode 3 and the steel plate 1 on both sides. A plurality of outer peripheral branch paths 2c are arranged along the width direction of the steel sheet 1 between the anode 3 and the rolls 4a and 4b in plan view. The outer peripheral branch 2 c includes an opening for supplying the plating bath 2 between the anode 3 and the steel plate 1.

  The upper tank 21a is provided with a discharge port (not shown) for discharging the plating bath 2, and is connected to the upper supply pipe 2a via a pipe (not shown) provided with 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 through the pipe and circulated again by the pump. It is a plating bath 2.

  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 penetrate the lower surface of the lower tank 21b. The lower supply pipe 2b is branched 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 along the width direction of the steel sheet 1 between the anodes 3 adjacent in a plan view. The intermediate branch 2 f includes an opening for supplying the plating bath 2 between the anode 3 and the steel plate 1 on both sides. A plurality of outer peripheral branch paths 2e are arranged along the width direction of the steel sheet 1 between the anode 3 and the rolls 5a and 5b in a plan view. The outer peripheral branch 2 e is provided with an opening for supplying the plating bath 2 between the anode 3 and the steel plate 1.

  The lower tank 21b is provided with a discharge port (not shown) for discharging the plating bath 2, and is connected to the lower supply pipe 2b via a pipe (not shown) provided with 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 and circulated again by the pump. It is a plating bath 2.

  When the energization time in the base formation process is adjusted to 0.05 seconds to 8.00 seconds, the intercrystalline filling region 32 stably shows an amorphous diffraction pattern.

In this embodiment, it is estimated that the plating layer 30 is formed on the surface of the steel plate 1 by the mechanism shown below. 4A to 4C are schematic diagrams for explaining the state of the surface of the steel sheet 1 in the process of manufacturing the surface-treated steel sheet 10 shown in FIG.
In the plating apparatus shown in FIG. 3, 18 A / dm ² or less comes into contact with the plating bath 2 sequentially from the portion that passes between the rolls 4 a and 5 a of the steel plate 1 on which the nickel plating layer (underlayer) 20 a is formed. Plating is started at a current density of.
That is, the rolls 4a and 5a are rolls for energizing and are also called conductor rolls. The steel plate and the plating solution come into contact after passing between the conductor rolls 4a and 5a.

In this embodiment, before zinc is deposited on the surface (solid-liquid interface) of the steel plate 1 on which the nickel plating layer 20a that has passed between the rolls 4a and 5a is formed, water is added as shown in FIG. 4A. The foundation | substrate formation process in which the vanadium compound 6 containing the summed vanadium oxide or vanadium hydroxide precipitates and an unevenness | corrugation is formed is started.
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. In the above-described base formation step, vanadium compound 6 containing hydrated vanadium oxide or vanadium hydroxide is deposited. This base is different from the base layer 20 described above. This foundation is finally taken into the plating layer 30.

  In the base formation step, when the precipitation of the vanadium compound 6 on the surface of the steel plate 1 is started, a plurality of current concentration portions 61 are formed on the surface of the steel plate 1 as shown in FIG. 4A. It can be presumed that the current concentration portion 61 is a portion where the current flows easily including a portion where the vanadium compound 6 is not deposited on the surface of the steel plate 1 or a portion where the precipitation amount is small.

When the current density is 21 A / dm ² or more, the Zn deposition potential is reached, and the Zn reduction deposition reaction is started. As shown in FIG. 4B, the dendrite-like crystal 3a containing metal zinc grows and the upper plating process is started. When the dendrite-like crystal 3a grows, it is estimated that the crystal grows more easily at the tip of the dendrite-like crystal 3a.

  In the upper plating step, as the dendrite-like crystal 3a grows, current concentrates on the tips of the branched branches of the dendrite-like crystal 3a, and as shown in FIG. 4C, It is estimated that hydrogen 62 is generated at the solid-liquid interface with the plating bath 2.

  The hydrogen 62 thus generated increases the pH of the solid-liquid interface between the surface of the dendritic crystal 3a and the plating bath 2. As a result, it is presumed that a crystal containing zinc oxide or zinc hydroxide is deposited so as to cover the surface of the dendrite-like crystal 31, and the dendrite-like crystal 31 having the surface layer 3b shown in FIG. 1 is formed. Further, due to the increase in pH of the plating bath 2, an amorphous material containing hydrated vanadium oxide or vanadium hydroxide is precipitated between adjacent dendritic crystals 31, and the intercrystalline filling region 32 shown in FIG. Presumed to be formed.

  In the present embodiment, as described above, the energization time is controlled in the range of 0.05 to 8.00 seconds in the base formation process. For this reason, before zinc precipitates on the surface of the steel plate 1, the precipitation of the vanadium compound 6 is started, and a plurality of current concentration portions 61 are formed on the surface of the steel plate 1. As a result, a dendrite-like crystal 31 is obtained by the mechanism described above, and it is presumed that an inter-crystal filling region 32 showing an amorphous diffraction pattern is obtained when electron beam diffraction is performed. The movement time of the steel sheet 1 passing through the interval D is more preferably in the range of 1.00 to 6.00 seconds.

If the energization time in the ground formation step is less than 0.05 seconds, the amount of vanadium compound 6 deposited before zinc is deposited on the surface of the steel sheet 1 is insufficient. For this reason, it becomes difficult for the dendrite-like crystal 31 made of metallic zinc to grow on the current concentration portion 61 formed on the surface of the steel plate 1. Further, the intercrystalline filling region 32 containing hydrated vanadium oxide or vanadium hydroxide cannot be obtained, or even if the intercrystalline filling region 32 is obtained, the amorphous diffraction pattern may become unstable. .
If the energization time in the base formation process exceeds 8.00 seconds, the amount of vanadium compound 6 deposited before zinc is deposited on the surface of the steel plate 1 becomes too large, and the current formed on the surface of the steel plate 1 The number of concentration parts 61 may be reduced or eliminated. For this reason, the dendrite-like crystal 31 made of metallic zinc is difficult to grow, and even if the dendrite-like crystal 31 and the intercrystalline filling region 32 are not obtained or the intercrystalline filling region 32 is obtained, an amorphous diffraction pattern is obtained. May become unstable.

In the present embodiment, in the base formation step, it is preferable to perform electroplating under conditions where the current density is 0 to 18 A / dm ^2, and it is more preferable to perform electroplating under conditions where the current density is ² to 15 A / dm ^2. preferable. By setting the current density in the base formation step to 18 A / dm ² or less, the molar ratio (V / Zn) between vanadium and zinc in the inter-crystal filling region 32 becomes 0.10 or more and 2.00 or less, and electrons When the line diffraction is performed, the intercrystalline filling region 32 shows an amorphous diffraction pattern, and as a result, the barrier property and the coating film adhesion can be improved. On the other hand, if the current density in the underlayer forming step is not within the above range, the intercrystalline filling region 32 is not formed, or even if the intercrystalline filling region 32 is formed, the amorphous diffraction pattern becomes unstable. .
In the upper layer plating step, it is preferable to perform electroplating under the conditions where the current density is 21~200A / dm ^2. By setting the current density to 21 A / dm ² or more, hydrogen 62 can be sufficiently generated at the solid-liquid interface between the end of the branch portion of the dendritic crystal 31 and the plating bath 2. Therefore, the precipitation amount of hydrated vanadium oxide or vanadium hydroxide contained in the inter-crystal filling region 32 increases. Therefore, the plating layer 30 having a high vanadium content and excellent barrier properties can be formed. On the other hand, if the current density exceeds 200 A / dm ² , the plating structure becomes rough or cracks are likely to occur, and the adhesion between the plating layer 30 and the steel sheet 1 may be reduced.

  The average flow rate of the plating bath 2 in the plating tank 21 when performing plating is preferably in the range of 20 to 300 m / min, and more preferably in the range of 40 to 200 m / min. When the average flow rate of the plating bath 2 is in the range of 20 to 300 m / min, it is possible to prevent the generation of cracks in the 30 plating layers and to supply ions from the plating bath 2 to the surface of the steel plate 1 without any trouble. it can.

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, the plating bath 2 may contain a pH adjuster, other metal compounds other than the V compound and the Zn compound, and additives as necessary.
Examples of the pH adjuster include H ₂ SO ₄ and NaOH.
Examples of the additive include Na ₂ SO ₄ that stabilizes the conductivity of the plating bath 2.

Examples of other metal compounds include nickel compounds such as NiSO ₄ .6H ₂ O. When the plating bath 2 contains a nickel compound, the plating bath 2 preferably contains Ni ^{2+ in an amount} of 0.01 mol / l or more. Thereby, the plating layer 30 containing nickel sufficiently can be formed. The plating layer 30 containing nickel is preferable because excellent plating adhesion can be obtained.

Examples of the Zn compound used in the plating bath 2 include metal Zn, ZnSO ₄ .7H ₂ O, ZnCO _{3 and the} like. 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), sodium metavanadate (V), VO (C ₅ H ₇ O ₂ ) ₂ (vanadyl acetylacetonate ( _{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 a bath containing Zn ²⁺ and VO ²⁺ .
Plating bath 2, when it is intended to include ^{Zn 2+,} preferably comprises ^{Zn 2+ 0.10~4.00mol} / l, more preferably contains 0.35~2.00mol / l.
When the plating bath 2 contains VO ²⁺ , it is preferable that the plating bath 2 contains VO ^{2+ in the range} of 0.01 mol / l to less than 2.00 mol / l. By using the plating bath 2 containing VO ²⁺ within the above range, the plating layer 30 having a high 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 is difficult to ensure the vanadium content in the plating layer 30. Further, if the content of VO ²⁺ contained in the plating bath 2 exceeds the above range, a large amount of expensive vanadium is used in the plating bath 2, which is economically disadvantageous.

Further, as the plating bath 2, it is preferable to use a bath containing Na ^{+ in an amount} of 0.10 mol / l or more. In this case, the conductivity of the plating bath 2 can be increased, and the plating layer 30 of this 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 ° C. in order to easily and efficiently form the plating layer 30 of the present embodiment.
Moreover, in order to form the plating layer 30 of this embodiment easily, the pH of the plating bath 2 is preferably in the range of 1 to 5, and more preferably in the range of 1.5 to 4.

In the present embodiment, after forming the plating layer 30, a treatment agent that improves barrier properties, fingerprint resistance, scratch resistance, lubricity, designability, and the like is applied on the plating layer 30 as necessary. It is preferable to form the surface layer 40.
Through the above steps, the surface-treated steel sheet 10 shown in FIG. 1 is obtained.

"Second embodiment, surface-treated steel sheet 210"
Hereinafter, the surface-treated steel sheet 210 of the second embodiment when the plating layer 230 contains zirconium will be described.
The surface-treated steel plate 210 of this embodiment includes a steel plate 201 and a plating layer 230 formed on one or both surfaces of the steel plate. The plating layer 230 contains zinc and zirconium. Further, the plating layer 230 contains a dendrite-like crystal 231 containing metallic zinc and an intercrystal filling region 232 containing one or both of hydrated zirconium oxide and zirconium hydroxide. Hereinafter, the surface-treated steel plate 210 will be described in detail.

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

As described above, the plating layer 230 includes the dendritic crystal 231 containing zinc metal and the intercrystal filling region 232 containing one or both of hydrated zirconium oxide and zirconium hydroxide.
The dendrite-like crystal 231 is a dendrite-like crystal phase containing metallic zinc, and the intercrystal filling region 232 contains one or both of hydrated zirconium oxide and zirconium hydroxide, and around the dendrite-like crystal 231. Formed and has an amorphous pattern by electron diffraction.
The plating layer 230 has a form in which the dendrite-like crystal 231 is deposited first, and then the inter-crystal filling region 232 is deposited around the dendrite-like crystal 231.

As described above, the dendrite-like crystal 31 of the first embodiment has the inner part 3a and the surface layer 3b. As described above, the interior 3a of the dendritic crystal 31 preferably contains metallic zinc, and may contain other metallic components such as nickel. On the other hand, the surface layer 3b of the dendritic crystal 31 preferably contains zinc oxide or zinc hydroxide, and more preferably contains hydrated zinc oxide crystals. On the other hand, the dendrite-like crystal 231 of this embodiment does not have an inner part and a surface layer.
The dendrite-like crystal 231 may be formed only from metal zinc, and may contain other metal components such as nickel which is more noble than the precipitation potential of zinc together with the metal zinc. The dendrite-like crystal 231 has a structure that grows from the steel plate 201 side toward the surface 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 dendrite-like crystal 231 contains metallic zinc, the sacrificial corrosion resistance can be imparted to the plating layer 230.

In addition to including one or both of hydrated zirconium oxide and zirconium hydroxide, the intercrystalline filling region 232 may include zinc oxide. When the inter-crystal filling region 232 includes these inclusions, barrier properties can be imparted to the plating layer 230. In addition, since the intercrystalline filling region 232 is mainly composed of a hydrated oxide or hydroxide, when a coating film is formed in the intercrystalline filling region 232, coating film adhesion can be ensured.
The intercrystal filling region 232 shows an amorphous diffraction pattern when electron beam diffraction is performed.

  When the intercrystalline filling region 232 includes hydrated zirconium oxide or zirconium hydroxide and zinc oxide, the molar ratio (Zr / Zn) of zirconium and zinc in the intercrystalline filling region 232 is 1. It is preferably from 00 to 3.00. When the above molar ratio (Zr / Zn) is in the above range, and when the electron beam diffraction is performed, the intercrystalline filling region 232 exhibits an amorphous diffraction pattern, whereby excellent corrosion resistance (barrier property) and Coating film adhesion is obtained.

An amorphous layer 250 that exhibits an amorphous diffraction pattern when electron beam diffraction is performed may be formed on the plating layer 230.
It is presumed that the amorphous layer 250 was formed first when the plating layer 230 was formed. That is, the amorphous layer 250 is first formed on the steel plate 201, and then, the plating layer 230 including the dendritic crystal 231 and the inter-crystal filling region 232 grows between the steel plate 201 and the amorphous layer 250. Presumed to be.

  The amorphous layer 250 is a layer mainly composed of zirconium oxide and may contain a trace amount of zinc. The amorphous layer 250 exhibits barrier properties when formed on the plating layer 230.

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. Through such a process, the amorphous layer 250 may be removed from the surface-treated steel plate 201.
By removing the amorphous layer 250, the plating layer 230 is exposed. The surface of the plating layer 230 has a surface roughness higher than that of the amorphous layer 250, and has excellent coating film adhesion 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 more preferably 3 g / m ² or more in order to improve the barrier property. Further, the adhesion amount of the plating layer 230 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 adhesion amount of the plating layer 230 is 20 g / m ² or less, the amount of metal to be deposited is smaller than that of conventional electrogalvanizing (usually about 20 g / m ² ). On the other hand, if the adhesion amount is too large, cracks are likely to occur in the plating layer 230.

  The thickness of the plating layer 230 is preferably in the range of 0.5 to 40 μm, more preferably in the range of 1.0 to 20 μm, and still more preferably in the range of 2.0 to 15 μm. If the thickness of the plating layer 230 is not less than the lower limit, the barrier property can be improved. Moreover, if the thickness of the plating layer 230 is less than or equal to the upper limit, cracks are unlikely to occur in the plating layer 230. The thickness of the plating layer 230 can be controlled by adjusting the amount of power that is applied when electroplating.

  The thickness of the amorphous layer 250 is preferably in the range of 0.20 to 2.00 μm, more preferably in the range of 0.30 to 1.50 μm, and still more preferably in the range of 0.50 to 1.00 μm. If the thickness of the amorphous layer 250 is not less than the upper limit, the plating layer 230 can be provided with a barrier property. Moreover, if the thickness of the amorphous layer 250 is below the lower limit, the occurrence of cracks can be prevented and the barrier property can be ensured. The thickness of the amorphous layer 250 can be controlled by adjusting the Zr concentration in the plating bath during electroplating. That is, the thickness of the amorphous layer 250 can be increased as the Zr concentration in the plating bath during electroplating is increased.

  The plating layer 230 has an average concentration of Zr: 3 to 40 atm%, Zn: 3 to 40 atm%, the remaining oxygen, and impurities. If Zr in the plating layer 230 is 3 atm% or more, the barrier property can be improved. Moreover, if Zr in the plating layer 230 is 40 atm% or less, the occurrence of cracks in the plating layer 230 can be prevented and barrier properties can be ensured. Moreover, if Zn in the plating layer 230 is 3 atm% or more, a sacrificial anticorrosive effect can be imparted to the plating layer 230. Moreover, if Zn 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 dendrite-like crystal 231 contains metal Zn as described above, and may contain Ni or the like.
When the dendrite-like crystal 231 is subjected to electron beam diffraction from the cross section of the plating layer 230 using a transmission electron microscope (TEM), a diffraction pattern resulting from the crystal structure is obtained.

  The inter-crystal filling region 232 is composed of Zr: 10 to 80 atm%, Zn: 3 to 40 atm%, the remaining oxygen, and impurities at an average concentration. If Zr in the inter-crystal filling region 232 is 10 atm% or more, the barrier property can be improved. Moreover, if Zr in the inter-crystal filling region 232 is 80 atm% or less, generation of cracks in the plating layer 230 can be prevented and barrier properties can be ensured. Moreover, if Zn in the intercrystal filling region 232 is 3 atm% or more, the barrier property can be improved. Moreover, if Zn in the intercrystal filling 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 Zr: 10 to 60 atm%, Zn: 0 to 15 atm%, the remaining oxygen, and impurities. If Zr in the amorphous layer 250 is 10 atm% or more, the barrier property can be improved. Moreover, if Zr in the amorphous layer 250 is 60 atm% or less, generation of cracks can be prevented and barrier properties can be secured. The amorphous layer 250 may contain a small amount of Zn or may not contain Zn.

  The point that the base layer 220 may be formed between the steel plate 201 and the plating layer 230 is the same as in the first embodiment.

  The surface layer 240 may be formed on 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 an L * value representing lightness 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 as a material having a black appearance. In particular, by setting the Zr concentration in the plating layer 230 to 5% by mass or more, the L * value can be reliably set to 40 or less.

  Moreover, although the surface-treated steel plate 210 of this embodiment of this embodiment demonstrated the example which formed the plating layer 230 on the steel plate 201, this embodiment is not restricted to this, An electrogalvanized steel plate, a hot dip galvanized steel plate The plated layer 230 of the present embodiment may be formed on the galvanized layer of the galvannealed steel sheet. That is, a second galvanized layer (not shown) containing zinc may be further formed between the steel plate 201 and the plated layer 230. By further forming a second galvanized layer (not shown), the corrosion resistance of the surface-treated steel sheet 210 can be further improved. For example, even when a corrosive substance passes through the plating layer 230, the sacrificial anticorrosive effect can be exhibited by the second galvanized layer (not shown), and the corrosion resistance of the surface-treated steel sheet 210 can be improved.

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

The manufacturing method of the surface-treated steel sheet 210 includes a base formation step and an upper layer plating step, as in the first embodiment. The same plating bath is used in the base formation step and the upper layer plating step, and a plating bath containing a Zr compound (ZrO ²⁺ ) and a Zn compound (Zn ²⁺ ) is used.
The Zr compound is preferably one that forms ZrO ²⁺ ions in the plating bath, and examples thereof include soluble salts such as zirconium nitrate oxide, zirconium sulfate oxide, and chlorinated zirconium oxide oxide. These may be used alone or in combination of two or more.

The plating bath preferably contains 0.10 to 4.00 mol / l of Zn ²⁺ , more preferably 0.50 to 2.00 mol / l. Moreover, it is preferable to contain 0.10-4.00 mol / l of ZrO2 ^+, and it is more preferable to contain 0.50-2.00 mol / l. By using a plating bath containing ZrO ²⁺ 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 is difficult to ensure the Zr content in the plating layer 230. Further, if the content of ZrO ²⁺ contained in the plating bath exceeds the above range, a large amount of Zr is used in the plating bath 2, which is economically disadvantageous.

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

  Since the current density in the underlayer forming step and the upper layer plating step is the same as that in the first embodiment, description thereof is omitted.

"Other examples"
The present invention is not limited to the embodiment described above.
In this embodiment, although the case where the plating layer was formed on both surfaces of the steel plate was described as an example, the plating layer may be formed only on one surface of the steel plate.
Moreover, although it is preferable that the foundation layer is formed between the steel plate and the plating layer, the foundation layer may not be formed. Moreover, when the plating layer is formed on both surfaces of the steel plate, the base layer may be formed only between the steel plate on one side and the plating layer.

  In this embodiment, although the case where a plating layer contains vanadium and the case where zirconium is included are described separately, you may provide these embodiments simultaneously.

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

  Moreover, in this embodiment, although the case where the surface-treated steel sheet was manufactured using the plating apparatus shown in FIG. 3 was described as an example, the plating apparatus for manufacturing the surface-treated steel sheet is used in the plating apparatus shown in FIG. It is not limited. For example, although four anodes 3 are arranged in the plating apparatus shown in FIG. 3, the number of anodes 3 may be any number. Further, the size and shape of the plating tank 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. It can be determined accordingly.

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

As the steel plate, an SPCD plate having a thickness of 0.5 mm, which is used for drawing a cold-rolled steel plate specified in JIS G 3141, was used.
The steel sheet was pretreated (nickel plating) and used as a cathode.
When performing the pretreatment, first, as a plating bath for nickel plating, ion-exchanged water, concentrated sulfuric acid, and NiSO ₄ .6H ₂ O are mixed to contain 60 g / L as Ni ²⁺ at 60 ° C. A pH of 2.0 was adjusted. Then, the steel plate was immersed in a plating bath, and the steel plate was used as a cathode, and a platinum electrode was used as an anode, and an electrolytic treatment was performed so that the Ni adhesion amount was 200 mg / m ² .
In the underlayer forming step and the upper layer plating step, each energization time was set to the time shown in Table 2 and Table 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 is used as the Zn compound, VOSO ₄ · 5H ₂ O is used as the V compound, and Na ₂ SO ₄ and other metal compounds are used as necessary. NiSO ₄ · 6H ₂ O was used. By adjusting the content thereof, ^Zn 2+ shown in Table ^{1, V (V 4+, VO} 2+), Na +, and adjusted to a concentration of ^{Ni 2+.}

  The plating layers of Examples and Comparative Examples thus obtained were observed with a field emission transmission electron microscope (FE-TEM) (manufactured by JEOL Ltd. (JED-2100F)).

  5A to 5C are transmission electron microscope (TEM) photographs of the plating layer of the surface-treated steel sheet of Example V4. 5A is a cross-sectional photograph of the entire thickness direction of the plating layer 30 formed on the steel plate 1, FIG. 5B is an enlarged photograph of the interface portion between the steel plate and the plating layer in the cross-section of FIG. 5A, and FIG. It is an enlarged photograph of the dendrite-like crystal and its peripheral part in the cross section.

  In FIG. 5B, the code | symbol 51 is a base layer and the code | symbol 52 is the intercrystal filling area | region of the interface vicinity of a steel plate and a plating layer. In FIG. 5C, reference numeral 53 denotes a dendrite-like crystal, reference numeral 54 denotes an intercrystal filling region, and reference numeral 55 denotes a surface layer formed on the surface of the dendrite-like crystal.

  As shown in FIGS. 5A to 5C, in the surface-treated steel sheet of Example V4, dendritic crystals, intercrystal filling regions, and surface layers of dendritic crystals were formed in the plating layer.

  Also about the plating layer of the surface-treated steel plate of Examples V1-V3 and V5-V20, it observed using TEM similarly to Example V4. As a result, a dendrite-like crystal, an intercrystal filling region, and a surface layer of the dendrite-like crystal were formed in the plating layer.

The plating layer of the surface-treated steel sheet of Example V4 was observed from the cross-sectional direction using a scanning electron microscope (SEM: A-4300SE manufactured by Hitachi, Ltd.). The observation of the plating layer was performed after depositing a gold film on the surface of the plating layer in order to facilitate observation of the surface shape of the plating layer.
FIG. 6 is a scanning electron microscope (SEM) photograph of the plated layer of the surface-treated steel sheet of Example V4. In FIG. 6, reference numeral 56 denotes a dendrite-like crystal, reference numeral 57 denotes an inter-crystal filling region disposed between the dendrite-like crystals, and reference numeral 58 denotes a surface layer covering the surface of the dendrite-like crystal. In the photograph shown in FIG. 6, the white portion on the surface of the plating layer is a gold film deposited for observing the plating layer.

  In the plated layers of the surface-treated steel plates of Examples V1 to V3 and V5 to V20, as in the plated layer of Example V4, dendritic crystals, intercrystalline filling regions, and surface layers of dendritic crystals were formed.

  About the plating layer of the surface treatment steel plate of the comparative example x1-comparative example x7, it observed using SEM similarly to Example V4. FIG. 7 is a scanning electron microscope (SEM) photograph of the plated 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 composed of dendritic crystals.

About the plating layers of Example V1 to Example V20, using an energy dispersive X-ray analyzer (EDS) (manufactured by JEOL Ltd. (JED-2300T)), a dendrite-like crystal, an intercrystalline filling region, a dendrite-like crystal Elemental analysis of the surface layer was performed. Then, the element (composition) contained in the dendrite-like crystal, the element (composition) contained in the intercrystalline filling region, the vanadium content and the zinc content, and the element (composition) contained in the surface layer of the dendrite-like crystal were examined.
In addition, the molar ratio (V / Zn) between the vanadium content and the zinc content in the intercrystalline filling region was calculated using the results of elemental analysis.

Also in the plating layers of Comparative Example x1 to Comparative Example x7, elemental analysis of the surface layer of dendritic crystals, intercrystalline filling regions, and dendritic crystals was performed in the same manner as in Examples V1 to V20.
The results are shown in Tables 4 and 5.

Moreover, about the plating layer of the surface treatment steel plate of Examples V1-V20, the surface layer of a dendrite-like crystal | crystallization, an intercrystal filling area | region, and a dendrite-like crystal | crystallization is respectively crystallized using the electron beam diffraction image obtained by TEM from the cross-sectional direction. It was confirmed whether it had a structure or was amorphous.
FIG. 8 is a photograph showing an electron diffraction image of the plating layer of Example V4. 8 correspond to the inter-crystal filling region 52, the dendrite-like crystal 53, the inter-crystal filling region 54, and the surface layer 55 of the dendrite-like crystal shown in FIGS. 5B and 5C, respectively.
From the electron diffraction pattern shown in FIG. 8, it was found that the dendrite-like crystal 53 and the surface layer 55 of the dendrite-like crystal have a crystal structure. Further, it was found that the intercrystalline filling regions 52 and 54 were amorphous because a diffraction pattern due to the crystal structure was not obtained.

The plated layers of the surface-treated steel sheets of Examples V1 to V3 and V5 to V20 are also similar to Example V4. I confirmed that it was. As a result, it was found that the dendrite-like crystal and the surface layer of the dendrite-like crystal had a crystal structure, and the intercrystalline filling region was amorphous.
When impurities in the dendrite-like crystal were examined, C, Si, S, Fe, and N were each about 0.1 to 5 atm%.

  The plated layers of the surface-treated steel sheets of Comparative Example x1 to Comparative Example x7 were analyzed using an X-ray diffractometer (XRD: RINT2500 manufactured by Rigaku Corporation). As a result, it was confirmed that the dendritic crystals had a Zn crystal structure for the plating layers of Comparative Examples x1 to x7. Further, except for the comparative example x7, when the intercrystalline filling region is not formed (comparative examples x4 and x6), or even if it is formed, only an unstable amorphous diffraction pattern can be obtained (comparative example). x1-x3 and x5) were confirmed.

  Moreover, about the plating layer of an Example and a comparative example, the following items were evaluated by the method shown below.

(Adhesion amount in the plating layer, vanadium content)
The adhesion amount of the plating layer was defined as the total mass per unit area of Zn element and V element detected using a fluorescent X-ray apparatus (Simulix 14 manufactured by Rigaku Corporation). The vanadium content in the plating layer was calculated as a percentage by dividing the amount of V element detected by the fluorescent X-ray apparatus by the amount of adhesion.

“Barrier”
The edge and the back surface of the test piece cut out from the surface-treated steel sheet were tape-sealed, and a salt spray test (JIS-Z-2371) was performed. And the white rust generation | occurence | production area ratio of the non-seal part 72 hours after was observed visually, and the following references | standards evaluated. The white rust generation area ratio is the percentage of the area of the white rust generation site to the area of the observation site.

(Standard)
5: White rust generation area ratio is less than 10%,
4: White rust generation area ratio 10% or more, less than 25% 3: White rust generation area ratio 25% or more, less than 50% 2: White rust generation area ratio 50% or more, less than 75% 1: White rust generation area ratio 75 %that's all

"Sacrificial protection"
The test piece cut out from the surface-treated steel plate was coated with a paint (Amirac # 1000, manufactured by Kansai Paint Co., Ltd.) and baked at 140 ° C. for 20 minutes to form a film having a dry film thickness of 25 μm. Then, the edge and back surface of the coated test piece were tape-sealed, and wrinkles were added to the surface so as to form an X shape with an NT cutter. And the salt spray test (JIS-Z-2371) was done, time until red rust generate | occur | produces from a collar part was measured, and the following references | standards evaluated.

(Standard)
5: Time to occurrence of red rust 960 hours or more 4: Time to occurrence of red rust 720 hours or more, less than 960 hours 3: Time to occurrence of red rust 480 hours or more, less than 720 hours 2: Time to occurrence of red rust 120 hours or more, 480 Less than time 1: Less than 120 hours until red rust occurs

(Powdering property (adhesion between plating layer and steel plate))
A 60 ° V bending mold was used for the powdering test. Bend to 60 ° using a die with a radius of curvature of 1 mm so that the evaluation surface of the test piece cut out from the surface-treated steel plate is inside the bent part, and then apply tape to the inside of the bent part The tape was peeled off. Powdering property (peeling width (mm)) was evaluated from the peeling state of the plating layer peeled off with the tape.

(Coating film adhesion)
The test piece cut out from the surface-treated steel plate was coated with a paint (Amirac # 1000, manufactured by Kansai Paint Co., Ltd.) and baked at 140 ° C. for 20 minutes to form a film having a dry film thickness of 25 μm. The obtained coated plate was immersed in boiling water for 30 minutes and then left in a room temperature room for 24 hours. Then, 100 squares of 1 mm square were cut into the test piece with an NT cutter, and this was extruded 7 mm with an Erichsen tester. Then, a peel test with an adhesive tape was performed on the extruded convex portion, and coating film adhesion ( The number of peels was evaluated.

As shown in Table 6 and Table 7, the surface-treated steel sheets of Examples V1 to V20 all satisfy the scope of the present invention, and compared with the surface-treated steel sheets of Comparative Example x1 to Comparative Example x7. It was found that the film was excellent in barrier properties and coating film adhesion.
Moreover, in the plating layer of the surface-treated steel sheet of Example V1 to Example V20 in which the current density in the base formation step is 0 to 18 A / dm ² , Comparative Example x2 in which the current density in the base formation step is 25 A / dm ² and Unlike the plating layer of the surface treated steel sheet of x3, when the molar ratio (V / Zn) of vanadium and zinc in the intercrystalline filling region is 0.10 or more and 2.00 or less, and electron beam diffraction is performed Shows a diffraction pattern in which the intercrystalline filling region is amorphous. Moreover, it turned out that barrier property and coating-film adhesiveness are more excellent.

"Test results of surface-treated steel sheet containing vanadium film"
The coating composition for forming the film comprises an organic resin (R), a phosphoric acid compound (P), carbon black (C), an organic silicon compound (W), and a fluorometal complex compound (shown in Table 8). F), the isocyanate compound (I), and the polyethylene wax (Q) are stirred in a solvent, water, using the content shown in Tables 9 and 10 (mass% of solid content) using a paint disperser. And dispersed to prepare a coating composition.

  In the preparation of the coating composition, the ratio of 3-aminopropyltriethoxysilane (W1) and 3-glycidoxypropyltrimethoxysilane (W2) shown in Table 8 to Table 9 and Table 10 [(W1) / (W2)] was added to the aqueous liquid containing the hydrolytic condensate dissolved in water so as to have the contents shown in Tables 9 and 10 as the organosilicon compound (W).

(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 case where no precipitate was generated was evaluated as paint stability “OK”, and the case where a precipitate was generated was evaluated as paint stability “NG”. The results of paint stability are shown in Table 9 and Table 10.

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

Next, a coating film was formed on the surface of the plating layer of the surface-treated steel sheet of Example V4 or Comparative Example x3 produced in (Example 1) by the method described below using each of the coating compositions.
First, the coating composition was applied to the surface of the surface-treated steel sheet using a roll coater so as to have the film thicknesses shown in Table 11 and Table 12. Thereafter, the surface-treated steel sheet coated with the coating composition was heated and dried so that the plate temperature reached 150 ° C., and spray-cooled with water to obtain a film. In addition, even after heating to 150 ° C., hydrated oxide was present in the plating layer.

Next, each surface-treated steel sheet having a coating formed on the surface of the plating layer was evaluated for appearance uniformity, corrosion resistance, conductivity, work adhesion, and scratch resistance. In addition, as reference example e2, the appearance uniformity, corrosion resistance, conductivity, work adhesion, and scratch resistance of the surface-treated steel sheet of Example V4 manufactured in (Example 1) were evaluated.
The evaluation results of each item are shown in Table 11 and Table 12.

The evaluation methods and evaluation criteria for each item are shown below.
(Appearance uniformity)
The L * value of the surface-treated steel sheet was measured using a colorimeter manufactured by Konica Minolta: CR-400 and evaluated according to the following evaluation criteria.

(Evaluation criteria)
5: L * value is 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 is more than 30

(Corrosion resistance)
The salt spray test (JIS Z 2371) was performed by tape-sealing the edges and back of the test piece cut out from the surface-treated steel sheet. And the white rust generation | occurrence | production area ratio of the non-seal part after 240 hours was observed visually, and the following references | standards evaluated. The white rust generation area ratio is a percentage of the area of the white rust generation site to the area of the observation site.

(Evaluation criteria)
6: White rust occurrence rate less than 3% 5: White rust occurrence rate 3% or more, less than 10% 4: White rust occurrence rate 10% or more, less than 25% 3: White rust occurrence rate 25% or more, less than 50% 2: White rust occurrence rate 50% or more, less than 75% 1: White rust occurrence rate 75% or more

(Conductivity)
Using the test piece cut out from the surface-treated steel sheet, the interlayer resistance value (Ω · cm ² ) was measured by the measurement method defined in JIS C 2550, and the conductivity was evaluated according to the following criteria.

(Evaluation criteria)
6: Interlayer resistance value is less than 1.0 Ω · cm ² 5: Interlayer resistance value is 1.0 Ω · cm ² or more and less than 1.5 Ω · cm ² 4: Interlayer resistance value is 1.5 Ω · cm ² or more Less than 0 Ω · cm ² 3: Interlayer resistance value is 2.0 Ω · cm ² or more, less than 2.5 Ω · cm ² 2: Interlayer resistance value is 2.5 Ω · cm ² or more, less than 3.0 Ω · cm ² 1: Interlayer Resistance value is 3.0 Ω · cm ² or more

(Processing adhesion)
The test piece cut out from the surface-treated steel sheet was subjected to 180 ° bending, and then a tape peeling test was performed on the outside of the bent portion. The appearance of the tape peeling part was observed with a magnifying glass having a magnification of 10 times and evaluated according to the following evaluation criteria. The bending process was performed in an atmosphere of 20 ° C. with a 0.5 mm spacer interposed therebetween.

(Evaluation criteria)
5: Peeling is not observed in the coating film 4: Peeling is observed in a part of the coating film (peeling area ≦ 2%)
3: Peeling is observed in some coating films (2% <peeling area ≦ 10%)
2: Peeling is observed in the coating film (10% <peeling area ≦ 20%)
1: Peeling is observed in the coating film (peeling area> 20%)

(Scratch resistance)
The test material cut out from the surface-treated steel sheet was brought into close contact with the electrogalvanized steel sheet (untreated material), and the test material was rotated 90 ° in a pressurized state. The pressure was 0.2 kg / cm ² and the test temperature was 25 ° C. Thereafter, the appearance of the test material was visually evaluated.

(Evaluation criteria)
6: No scratches are visible.
5: Although there are fine scratches, the substrate is not exposed 4: The substrate is slightly exposed (exposed area: less than 3%)
3: The substrate is exposed (exposed area: 3% or more, less than 10%)
2: The substrate is exposed (exposed area: 10% or more, less than 30%)
1: The substrate is exposed (exposed area: 30% or more)

  As shown in Table 11 and Table 12, in Examples t1 to t14 having a film on the surface of the plating layer of the surface-treated steel sheet of Example V4, the evaluation result is 2 or more of the evaluation criteria in any evaluation item. Excellent appearance uniformity, corrosion resistance, electrical conductivity, work adhesion and scratch resistance. Moreover, Examples t1-t14 had favorable corrosion resistance and electroconductivity compared with the reference example e2 which has not formed the film | membrane on the surface.

  On the other hand, Comparative Example w1-w5 which has a film | membrane on the surface of the plating layer of the surface treatment steel plate of Comparative Example x3 has 1 evaluation results of appearance uniformity, corrosion resistance after 240 hours, work adhesion, and scratch resistance. The performance was inferior.

"Test results for zirconium-containing surface-treated steel sheets"
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 prepared and evaluated by the following method.
Note that a description of the same matters as in the first embodiment is omitted.
A plating bath in a fluid state was prepared by circulating a plating bath having the composition, temperature, and pH shown in Table 13 at an average relative flow rate of 100 m / min.

  And the pre-processing (nickel plating) was used for the steel plate as a cathode. In the underlayer forming step and the upper layer plating step, the energization time was set to the times shown in Table 14 and Table 15, the current density was set to the values shown in Tables 14 and 15, and the plating layer was formed by electroplating.

In the plating bath composition shown in Table 13, ZnSO ₄ · 7H ₂ O is used as the Zn compound, ZrO (NO ₃ ) ₂ aqueous solution or ZrOSO ₄ aqueous solution is used as the Zr compound, and Na ₂ SO ₄ , etc. as necessary. NiSO ₄ · 6H ₂ O was used as the metal compound. By adjusting the content thereof, ^Zn 2+ shown in Table ^{1, Zr (Zr 4+, ZrO} 2+), Na +, and adjusted to a concentration of ^{Ni 2+.}

  The plating layers of Examples and Comparative Examples thus obtained were observed with a field emission transmission electron microscope (FE-TEM) (manufactured by JEOL Ltd. (JED-2100F)).

FIG. 9 is a transmission electron microscope (TEM) photograph of the plated layer of the surface-treated steel sheet of Example Z4.
As shown in FIG. 9, it can be seen that the plating layer of the present embodiment is formed with dendrite-like crystals, an intercrystalline filling region formed in the periphery thereof, and an amorphous layer in the surface layer portion. Dendritic crystals were found to be composed of metallic Zn by elemental analysis and electron diffraction analysis using an energy dispersive X-ray analyzer (EDS (manufactured by JEOL Ltd. (JED-2300T)). Was found to contain zirconium oxide and zirconium hydroxide, and the amorphous layer in the surface layer portion was found to be composed of zirconium oxide.

  Also in the plating layers of the other examples, as in Example Z4, dendritic crystals, intercrystalline filling regions formed around them, and an amorphous layer in the surface layer portion were formed. In some cases, the amorphous layer in the surface layer portion was removed.

About the plating layer of Example Z1-Example Z20, using an energy dispersive X-ray analyzer (EDS) (manufactured by JEOL Ltd. (JED-2300T)), “dendritic crystal”, “intercrystalline packing region”, “ Elemental analysis of the surface layer of dendritic crystals was performed. Then, the element (composition) contained in the dendrite-like crystal, the element (composition) contained in the intercrystalline filling region and its zirconium content and zinc content, and the element (composition) contained in the surface layer of the dendrite-like crystal were examined.
Moreover, the molar ratio (Zr / Zn) of the amount of zirconium and the amount of zinc in the intercrystalline filling region was calculated using the results of elemental analysis.

Also in the plating layers of Comparative Example x11 to Comparative Example x16, elemental analysis of “dendritic crystals”, “intercrystalline filling region”, and “surface layer of dendritic crystals” was performed in the same manner as in Examples Z1 to Z20.
The results are shown in Tables 16-17.

About the plating layer of the surface-treated steel sheet of Example Z1 to Example Z20, it was confirmed whether “dendritic crystal”, “intercrystalline filling region”, and “surface layer of dendritic crystal” had a crystal structure or were amorphous. . As a result, it was found that the dendrite-like crystal and the surface layer of the dendrite-like crystal had a crystal structure, and the intercrystalline filling region was amorphous.
When impurities in the dendrite-like crystal were examined, C, Si, S, Fe, and N were each about 0.1 to 5 atm%.

  The plated layers of the surface-treated steel sheets of Comparative Example x11 to Comparative Example x16 were analyzed using an X-ray diffractometer (XRD: RINT2500 manufactured by Rigaku Corporation). As a result, it was confirmed that the dendritic crystals had a Zn crystal structure for the plating layers of Comparative Examples x11 to x16. In addition, it is confirmed that the intercrystalline filling region is not formed (Comparative Example x15) or that only unstable amorphous diffraction patterns can be obtained (Comparative Examples x11 to x14 and x16). did.

  Moreover, about the plating layer of an Example and a comparative example, the following items were evaluated by the method shown below.

(Amount of deposition in the plating layer, zirconium content)
The adhesion amount of the plating layer was defined as the total mass per unit area of the Zn element and the Zr element detected using a fluorescent X-ray apparatus (Simulix 14 manufactured by Rigaku Corporation). The zirconium content in the plating layer was calculated as a percentage by dividing the amount of Zr element detected by a fluorescent X-ray apparatus by the amount of adhesion.

As shown in Table 18 and Table 19, Examples Z1 to Z20 all satisfy the scope of the present invention. Compared with the surface-treated steel sheets of Comparative Example x11 to Comparative Example x16, barrier properties and coating It was found that the film adhesion was excellent.
Moreover, in the plating layer of the surface treatment steel plate of Example Z1-Example Z20 whose current density in a base | substrate formation process is 0-18A / dm < ² >, the comparative example x12- whose current density in a base | substrate formation process is 25 A / dm < ² >-. Unlike the plated layer of x13 surface-treated steel sheet, when the molar ratio (Zr / Zn) of zirconium to zinc in the intercrystalline filling region is 1.00 or more and 3.00 or less and electron beam diffraction is performed Shows a diffraction pattern in which the intercrystalline filling region is amorphous. Moreover, it turned out that barrier property and coating-film adhesiveness are more excellent.

"Test results of surface-treated steel sheet containing zirconium film"
The coating composition for forming the film comprises an organic resin (R), a phosphoric acid compound (P), carbon black (C), an organic silicon compound (W), and a fluorometal complex compound (shown in Table 8). F), the isocyanate compound (I), and the polyethylene wax (Q) are agitated by using a disperser for paint in water as a solvent with the contents (mass% of solid content) shown in Table 20 and Table 21. And dispersed to prepare a coating composition.
Note that a description of the same matters as in the second embodiment will be omitted.

  As shown in Table 20 and Table 21, the coating composition used in Examples u1 to u14 and Comparative Examples y1 to y5 had a coating stability result of “OK” and was excellent in stability.

Next, a coating film was formed on the surface of the plating layer of the surface-treated steel sheet of Example Z4 or Comparative Example x13 produced in (Example 3) by the following method using the coating composition.
First, the coating composition was applied to the surface of the surface-treated steel sheet using a roll coater so that the film thicknesses shown in Table 22 and Table 23 were obtained. Thereafter, the surface-treated steel sheet coated with the coating composition was heated and dried so that the plate temperature reached 150 ° C., and spray-cooled with water to obtain a film. In addition, even after heating to 150 ° C., hydrated oxide was present in the plating layer.

Next, each surface-treated steel sheet having a coating formed on the surface of the plating layer was evaluated for appearance uniformity, corrosion resistance, conductivity, work adhesion, and scratch resistance. Further, as Reference Example f1, evaluation was performed on appearance uniformity, corrosion resistance, conductivity, work adhesion, and scratch resistance of the surface-treated steel sheet of Example Z4 manufactured in (Example 3).
The evaluation results of each item are shown in Table 22 and Table 23.

  As shown in Table 22 and Table 23, Examples u1 to u14 having a coating on the surface of the plated layer of the surface-treated steel sheet of Example Z4 have an evaluation result of 2 or more of the evaluation criteria in any evaluation item. Excellent appearance uniformity, corrosion resistance, electrical conductivity, work adhesion and scratch resistance. Moreover, Examples u1-u14 had favorable corrosion resistance and electroconductivity compared with the reference example f1 which has not formed the film | membrane on the surface.

  On the other hand, Comparative Examples y1 to y5 having a film on the surface of the plating layer of the surface-treated steel sheet of Comparative Example x13 have an evaluation result of 1 for appearance uniformity, corrosion resistance after 240 hours, work adhesion, and scratch resistance. The performance was inferior.

  As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be envisaged within the scope of the claims, and these are naturally within the technical scope of the invention. Is done.

  According to each said embodiment, the surface treatment steel plate excellent in the barrier property and coating-film adhesiveness in which the plating layer containing zinc and vanadium was formed in the surface of a steel plate can be provided.

1,201 Steel plate 2 Plating bath 2a Upper supply pipe 2b Lower supply pipe 2c, 2e Outer peripheral branch 2d, 2f Intermediate branch 3 Anode 3a Inside of dendritic crystal 3b, 55, 58 Surface layer of dendritic crystal 3c Granular crystal 4a, 5a, 4b, 5b Roll 6 Vanadium compound 10, 210 Surface-treated steel plate 20, 51, 220 Underlayer 20a Nickel plating layer 21 Plating tank 21a Upper tank 21b Lower tank 30, 230 Plating layer 31, 53, 56, 231 Dendrite Crystals 32, 52, 54, 57, 232 Inter-crystal filling region 40, 240 Surface layer 61 Current concentration portion 62 Hydrogen 250 Amorphous layer D Distance between rolls 4a and 5a and anode 3

Claims (6)

With steel plate;
A plating layer formed on one or both sides of the steel sheet and containing zinc and vanadium or zirconium;
With
The plating layer is
Dendritic crystals containing metallic zinc;
An intercrystalline filling region that fills between the dendritic crystals and exhibits an amorphous diffraction pattern when electron diffraction is performed;
Have
When the plating layer contains the vanadium, the intercrystalline filling region contains a hydrated vanadium oxide or vanadium hydroxide,
A surface-treated steel sheet, wherein the intercrystalline filling region contains hydrated zirconium oxide or zirconium hydroxide when the plating layer contains zirconium. When the plating layer contains the vanadium, V / Zn which is a molar ratio of the vanadium and the zinc in the inter-crystal filling region is 0.10 or more and 2.00 or less,
When the plating layer contains the zirconium, Zr / Zn which is a molar ratio of the zirconium and the zinc in the inter-crystal filling region is 1.00 or more and 3.00 or less. Item 11. The surface-treated steel sheet according to Item 1. When the plating layer contains the vanadium,
The surface-treated steel sheet according to claim 1 or 2, wherein the surface layer of the dendrite-like crystal contains zinc oxide or zinc hydroxide. The base plating layer whose Zn / V which is the molar ratio of zinc and the said vanadium is 8.00 or more is further provided between the said steel plate and the said plating layer, The Claim 1 characterized by the above-mentioned. The surface-treated steel sheet according to any one of Items 3. The surface according to any one of claims 1 to 4, further comprising an organic resin film having a polyurethane resin and 1 to 20% by mass of carbon black on the surface of the plating layer. Treated steel sheet. A method for producing the surface-treated steel sheet according to any one of claims 1 to 5,
Using a plating bath containing 0.10 to 4.00 mol / l Zn ²⁺ ions and 0.01 to 2.00 mol / l V ions or 0.10 to 4.00 mol / l Zr ions, A base formation step of forming irregularities by depositing hydrated vanadium oxide or vanadium hydroxide on the steel sheet by electroplating at a current density of 0 to 18 A / dm ² ;
An upper plating step in which electroplating is performed on the steel sheet on which the irregularities have been formed at a current density of 21 to 200 A / dm ² using the plating bath;
A method for producing a surface-treated steel sheet, comprising: