JP6121227B2 - Method for producing black-plated steel sheet - Google Patents

Description

  The present invention relates to a method for producing a black-plated steel sheet.

  In the fields of building roofing materials, exterior materials, home appliances, automobiles, and the like, there is an increasing need for steel plates having a black appearance from the viewpoint of design and the like. As a method for blackening the surface of a steel plate, there is a method of forming a black coating film by applying a black paint to the surface of the steel plate. There is also a method of blackening the plated layer itself of the plated steel plate to blacken the surface of the plated steel plate. For example, Patent Document 1 discloses a method in which a molten Al-containing Zn-plated steel sheet is steam-treated in a hot and humid atmosphere to oxidize the surface of the molten Al-containing Zn plated layer to form a thin black film on the surface of the plated layer. It is disclosed.

  By the way, from the viewpoint of designability and corrosion resistance, a surface treatment technique (blueing) is known in which the surface of a steel plate is oxidized to form a blue film on the surface of the steel plate. For example, Patent Literature 2 discloses a method of bluing by heating a coil wound with a steel strip in an oxidizing atmosphere. In the method of patent document 2, in order to expose the surface of a steel strip, the metal wire (wire) is arrange | positioned as a spacer between the steel strips of a coil.

Japanese Patent Application Laid-Open No. 64-056881 JP 63-161126 A

  When producing a black-plated steel sheet by subjecting a plated steel sheet to steam treatment as in the technique of Patent Document 1, the manufacturing process becomes complicated if the plate-shaped plated steel sheet is subjected to steam treatment one by one. Cost increases. Therefore, the present inventors tried to perform the steam treatment as it is on the coil of the plated steel plate, but the water vapor did not enter between the steel strips, and the surface of the plated steel plate could not be uniformly blackened.

  Then, the present inventors tried to perform the steam treatment in a state where metal wires (spacers) are arranged between the steel strips (plated steel plates) of the coil with reference to the method of Patent Document 2. However, in this method, corrosion occurs on the surface of the plated steel sheet, and a high-quality black-plated steel sheet cannot be obtained.

  This invention is made | formed in view of this point, and it aims at providing the manufacturing method of a black plating steel plate which can manufacture a black plating steel plate efficiently, without generating corrosion on the surface of a plating layer. And

  The inventors of the present invention have found that the above-mentioned problems can be solved by performing a steam treatment in a state in which a spacer whose surface is made of an insulator is disposed between plated steel sheets, and further studies have been made to complete the present invention.

That is, this invention relates to the manufacturing method of the following black plated steel plates.
[1] Step of preparing Al: 0.1 to 22.0 mass%, Mg: molten Al containing 0.1 to 10.0 mass%, molten Al having an Mg-containing Zn plating layer, Mg-containing Zn-plated steel sheet And a step of bringing the molten Al, Mg-containing Zn-plated steel plate into contact with water vapor in a state where a spacer made of an insulator is disposed between the molten Al and Mg-containing Zn-plated steel plate. And a method for producing a black-plated steel sheet.
[2] The method for producing a black-plated steel sheet according to [1], wherein the spacer is made of a metal wire coated with a resin, a resin wire, or a combination thereof.
[3] The method for producing a black-plated steel sheet according to [2], wherein the spacer is a concentric stranded wire, a collective stranded wire, or a knitted wire made of a metal wire coated with a resin, a resin wire, or a combination thereof.
[4] The method for producing a black-plated steel sheet according to [1], wherein the spacer is paper, cloth, or nonwoven fabric.
[5] The size of the molten Al and Mg-containing Zn-plated steel sheet is 500 mm wide × 500 mm long, the spacer is made of synthetic fiber, has a thickness of 0.3 mm or more, and an air flow of 30 cc / cm ² / s. The manufacturing method of the black plating steel plate as described in [1] which is the above nonwoven fabric.

  ADVANTAGE OF THE INVENTION According to this invention, a black plating steel plate can be manufactured efficiently, without producing corrosion on the surface of a plating layer.

FIG. 1A is a schematic view of a concentric stranded linear spacer. FIG. 1B is a schematic diagram of a linear spacer of an aggregate stranded wire type. FIG. 1C is a schematic diagram of a knitted wire-type linear spacer. FIG. 1D is a schematic diagram of a single-line linear spacer. FIG. 2A is a schematic diagram showing a state in which linear spacers are arranged on a plated steel sheet. FIG. 2B is a schematic diagram illustrating a measurement position of brightness. FIG. 2C is a schematic diagram showing a state in which planar spacers are arranged on the plated steel sheet. FIG. 3A is a photograph of a planar spacer when viewed in plan. FIG. 3B is a photograph of a cross-section of part A shown in FIG. 3A. FIG. 3C is an enlarged photograph of the broken line part of FIG. 3B. FIG. 3D is a photograph of a cross section of part B shown in FIG. 3A. FIG. 4A is a photograph of a cross section of a planar spacer made of polypropylene before steaming. FIG. 4B is a photograph of a cross section of a planar spacer made of polypropylene after steam treatment. FIG. 4C is a photograph of a cross section of a planar spacer made of polyethylene terephthalate after steam treatment.

  The method for producing a black-plated steel sheet according to the present invention includes (1) a first step of preparing a molten Al, Mg-containing Zn-plated steel sheet (hereinafter also referred to as “plated steel sheet”), and (2) a spacer disposed between the plated steel sheets. And a second step of bringing the plated steel plate into contact with water vapor. Furthermore, as an optional step, it may have a step of (3) forming an inorganic coating or an organic resin coating on the surface of the plated steel sheet before or after the second step.

1. First Step In the first step, a molten Al / Mg-containing Zn plated steel sheet having a molten Al / Mg-containing Zn plated layer (hereinafter also referred to as “plated layer”) formed on the surface of the base steel sheet is prepared.

[Base steel sheet]
The kind of base steel plate is not particularly limited. For example, as the base steel plate, a steel plate made of low carbon steel, medium carbon steel, high carbon steel, alloy steel, or the like can be used. When good press formability is required, a steel sheet for deep drawing made of low carbon Ti-added steel, low carbon Nb-added steel, or the like is preferable as the base steel sheet. Moreover, you may use the high strength steel plate which added P, Si, Mn, etc.

[Molded Al, Mg-containing Zn plating layer]
As the original plate of the black-plated steel sheet of the present invention, Al: 0.1 to 22.0 mass%, Mg: molten Al containing 0.1 to 10.0 mass%, molten Al having an Mg-containing Zn plating layer, Mg A contained Zn-plated steel sheet is preferably used. When the content of Al or Mg exceeds the upper limit value, a lot of dross is generated during plating, and the appearance of the plating layer is impaired. On the other hand, when the Al content is less than the lower limit, the adhesion of the plating may be reduced. Moreover, when content of Mg is less than a lower limit, there exists a possibility that the blackening speed | rate may fall.

  In addition, in this specification, the value of the content of each component in the plating layer is expressed as a percentage obtained by dividing the mass of each metal component contained in the plating layer by the mass of all metals contained in the plating layer. It is. That is, the mass of oxygen and water contained in the oxide and hydrated oxide is not included as a component in the plating layer. Therefore, when the elution of the metal component does not occur during the steam treatment, the value of the content of each component in the plating layer does not change before and after the steam treatment. In the present specification, oxides and hydrated oxides are collectively referred to as oxides.

Currently, the molten Al- and Mg-containing Zn-plated steel sheets that are most widely distributed in the market contain about 6 mass% Al and about 3 mass% Mg in the plating layer. In the case of such a plating composition, the metal structure of the plating layer is mainly a mixture of primary crystal Al phase and Al / Zn / Zn ₂ Mg ternary eutectic structure. Here, the phases (Al phase, Zn phase and Zn ₂ Mg phase) forming the ternary eutectic structure of Al / Zn / Zn ₂ Mg have irregular sizes and shapes, respectively, Yes. The Al phase in the primary eutectic Al phase and the Al / Zn / Zn ₂ Mg ternary eutectic structure is the Al ”phase (Zn solid solution at high temperature in the Al—Zn—Mg ternary equilibrium diagram). This is a solid solution of Al and contains a small amount of Mg. The Al "phase at high temperature usually appears separated into a fine Al phase and a fine Zn phase at room temperature. The Zn phase in the ternary eutectic structure is a Zn solid solution in which a small amount of Al is dissolved, and in some cases, Mg is further dissolved. The Zn ₂ Mg phase in the ternary eutectic structure is an intermetallic compound phase in the vicinity of a point where Zn is about 84% by mass in the Zn—Mg binary equilibrium diagram.

As the molten Al and Mg-containing Zn plating layer, for example, a layer composed of Al: 0.1 to 22.0 mass%, Mg: 0.1 to 10.0 mass%, balance: Zn and inevitable impurities can be used. It is. Moreover, in order to improve the adhesiveness of a base steel plate and a plating layer, Si which can suppress the growth of the Al-Fe alloy layer in the interface of a base steel plate and a plating layer is 0.005 mass%-2.0 mass. % May be added to the plating layer. If the Si concentration exceeds 2.0 mass%, there is a possibility that a Si-based oxide that inhibits blackening may be generated on the surface of the plating layer. Further, in order to suppress the formation and growth of Zn ₁₁ Mg ₂ phase adversely affecting the appearance and corrosion resistance, Ti, B, Ti-B alloy, a Ti-containing compound or a B-containing compound may be added to the plating layer. The amount of these compounds added is set so that Ti is in the range of 0.001% to 0.1% by mass and B is in the range of 0.0005% to 0.045% by mass. It is preferable to do. If an excessive amount of Ti or B is added, there is a possibility that precipitates grow on the plating layer. In addition, the addition of Ti, B, Ti—B alloy, Ti-containing compound or B-containing compound into the plating layer hardly affects the blackening due to the steam treatment.

  Although the thickness of a plating layer is not specifically limited, The inside of the range of 3-100 micrometers is preferable. When the thickness of the plating layer is less than 3 μm, scratches that reach the base steel sheet during handling are likely to occur, so that the black appearance retention and corrosion resistance may be reduced. On the other hand, when the thickness of the plating layer exceeds 100 μm, since the ductility of the plating layer and the base steel plate when subjected to compression is different, the plating layer and the base steel plate may be peeled off at the processed portion.

2. Second Step In the second step, the plated steel sheet is made black by bringing the plated steel sheet into contact with water vapor in a state where the spacer is disposed between the plated steel sheets. The degree of blackening of the plating layer is determined by the brightness (L ^* value) of the surface of the plating layer. The lightness (L ^* value) of the plating layer surface is measured by a spectral reflection measurement method based on JIS K 5600 using a spectral color difference meter.

Although the mechanism by which the plating layer is blackened by the steam treatment is unknown, one hypothesis is that Zn, Al, Mg oxide (having an oxygen-deficient defect structure in the plating layer surface and the plating layer by the steam treatment ( For example, it is presumed that ZnO _1-x , Al ₂ O _3-x, etc.) are generated. When an oxygen-deficient oxide is generated in this manner, light is trapped in the defect order, and the oxide exhibits a black appearance.

[Steam treatment]
The temperature of the steam treatment is preferably in the range of 50 to 350 ° C, more preferably in the range of 105 to 200 ° C. When the temperature of the water vapor treatment is less than 50 ° C., the blackening speed is slow and productivity is lowered. On the other hand, when the temperature of the steam treatment is higher than 350 ° C., the blackening speed becomes very fast and it becomes difficult to control. Further, when the temperature of the steam treatment is higher than 350 ° C., not only the treatment apparatus becomes large, but also the time required for heating and cooling becomes long, which is not practical.

  The relative humidity of water vapor during the water vapor treatment is preferably in the range of 30% or more and 100% or less, and more preferably in the range of 30% or more and less than 100%. When the relative humidity of the water vapor is less than 30%, the blackening speed is slow and the productivity is lowered. Moreover, when the relative humidity of water vapor | steam is 100%, there exists a possibility that dew condensation may adhere to the surface of a plated steel plate, and an external appearance defect may arise easily.

  The atmospheric pressure of water vapor during the water vapor treatment is not particularly limited, and may be normal pressure (atmospheric pressure) or may be pressurized. Under normal pressure (atmospheric pressure), when water vapor adjusted to the specified temperature and relative humidity is sprayed onto the plated steel sheet, the temperature and relative humidity of the water vapor change depending on the distance between the outlet and the plated steel sheet and the ambient temperature. There is a risk of it. In order to avoid such a problem, it is preferable to bring the plated steel sheet into contact with water vapor in a closed container adjusted to a predetermined temperature and relative humidity.

  The treatment time for the water vapor treatment can be appropriately set according to the conditions for the water vapor treatment (temperature, relative humidity, pressure, etc.), the amounts of Al and Mg in the plating layer, the required brightness, and the like.

[spacer]
In the method for producing a black-plated steel sheet of the present invention, from the viewpoint of improving the production efficiency, the steam treatment is performed on, for example, a coil wound with a plated steel sheet (steel strip) or a laminated body of flat-plate plated steel sheets. Is called. In this way, when performing steam treatment on the coil or laminated body of the plated steel plate, there is almost no gap between the plated steel plates, so the amount of water vapor contacting the peripheral portion and the central portion of the plated steel plate is greatly different. . Thus, if the amount of water vapor that contacts the surface of the plating layer varies from place to place, unevenness occurs in the degree of blackening of the surface of the plating layer. The unevenness of the degree of blackening on the surface of the plating layer becomes more noticeable as the plated steel sheet becomes larger, and becomes more noticeable as the temperature and relative humidity of the water vapor treatment become higher.

  In the manufacturing method of the black plating steel plate of this invention, in order to eliminate such a problem, it is supposed that a spacer is arrange | positioned between plating steel plates. By arranging a spacer between the plated steel sheets and forming a gap in which the water vapor can move between the plated steel sheets in this way, the water vapor can contact the central portion as well as the peripheral edge of the plated steel sheet. The surface of the plating layer can be blackened almost uniformly. The distance between the plated steel sheets is preferably 0.05 mm or more from the viewpoint of allowing water vapor to easily enter. In addition, a spacer may be arrange | positioned between the same plated steel plates (for example, in the case of a coil), and may be arrange | positioned between different plated steel plates (for example, laminating flat plate-shaped plated steel plates). If).

  Moreover, in the manufacturing method of the black plating steel plate of this invention, the spacer which is coat | covered with the insulator or consists of an insulator is used as a spacer arrange | positioned between plating steel plates. In this way, by using a spacer whose surface is made of an insulator, it is possible to prevent the occurrence of electric corrosion at the contact portion between the spacer and the plating layer, and to prevent corrosion of the plating layer surface layer during the steam treatment. can do. The kind of insulator is not particularly limited. Examples of the insulator include resin, synthetic fiber, natural fiber, inorganic oxide (for example, inorganic oxide carbide, inorganic oxynitride, inorganic boride, and the like) as described later.

  The shape of the spacer is not particularly limited. Examples of the shape of the spacer include a linear spacer and a planar spacer described below.

  The linear spacer is a linear spacer made of one or more wire rods (elementary wires). A linear spacer is arrange | positioned in a part of surface of a plated steel plate, and provides a clearance gap between plated steel plates. The material of the linear spacer is not particularly limited as long as it is not significantly deteriorated, ignited, and fused with the plated steel sheet during the steam treatment. For example, the linear spacer is made of a metal wire coated with a resin, a resin wire, or a combination thereof. The type of the resin that coats the metal wire and the resin (insulator) that constitutes the resin wire is not particularly limited as long as it has insulating properties and can withstand the temperature of the water vapor treatment. From the viewpoint of blackening also in the contact portion, those that can permeate water vapor to some extent are preferable. Examples of such resins include fluororesins such as polytetrafluoroethylene, polyamides such as nylon 6 and nylon 66, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, and the like. The kind of metal wire is not particularly limited. For example, the metal wire is a wire made of stainless steel.

  The shape of the linear spacer is not particularly limited. Examples of the shape of the linear spacer include a concentric stranded wire type shown in FIG. 1A, a collective stranded wire type shown in FIG. 1B, a knitted wire type shown in FIG. 1C, and a single wire type shown in FIG. 1D. Among these, the concentric stranded wire type, the collective stranded wire type, and the braided wire type are particularly preferable because a gap through which water vapor can pass is formed between the plated steel plate and the plated steel plate. When the linear spacer is a concentric stranded wire type or a collective stranded wire type, a gap is generated by twisting the strands. Further, when the linear spacer is a knitted wire type, a gap can be provided not only in the gap generated by knitting the strand but also in the knitted wire itself. The number of strands of the concentric stranded wire type and the collective stranded wire type is not particularly limited as long as it is two or more.

  The strand diameter is not particularly limited. When the wire diameter is excessively large, water vapor easily passes through, but the size of the coil or flat plate laminate after the linear spacers are arranged becomes large, and the apparatus for water vapor treatment becomes large. On the other hand, when the strand diameter is excessively small, the tensile breaking strength of the linear spacer is reduced, and there is a possibility of breaking when the linear spacer is disposed. Therefore, the wire diameter may be appropriately adjusted in consideration of the manufacturability of the black-plated steel sheet and the tension applied when arranging the linear spacers. The strand diameter is usually about 0.5 to 2.0 mm.

  The method for arranging the linear spacers between the plated steel sheets is not particularly limited. When the plated steel sheet is wound in a coil shape, the steel strip may be loosened and inserted between the steel strips. Moreover, you may wind in a coil shape in the state which accumulated the steel strip and the planar spacer. Furthermore, when laminating a flat plated steel sheet, a linear spacer may be disposed on the peripheral edge of the plated steel sheet and laminated.

  The planar spacer is a flat plate member having water vapor permeability. A planar spacer is arrange | positioned at the whole surface of a plated steel plate, and provides a clearance gap between plated steel plates. The shape of the planar spacer is not particularly limited, but is preferably a material that allows water vapor to pass therethrough, such as a woven fabric, a knitted fabric, or a film-like member having a plurality of holes (openings). For example, the planar spacer is paper, cloth, nonwoven fabric, parchment or the like made of synthetic fiber, natural fiber, or a combination thereof.

  The material of the planar spacer is not particularly limited, but is preferably a material that has insulating properties, easily passes through water vapor, and does not easily hold water vapor. When the planar spacer is made of a material excellent in water vapor retention, a water film may be formed in the planar spacer to inhibit the movement of water vapor. Examples of planar spacer materials include fluororesins such as polytetrafluoroethylene, polyamides such as nylon 6 and nylon 66, polypropylene, polyethylene, polystyrene, polyester, EVA copolymer, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, Synthetic fiber made of resin such as cellulose acetate, polycarbonate, polybutylene, urethane resin, acrylic resin, epoxy resin; plant fiber such as pulp, bamboo, cellulose, hemp, cotton, linen; animal fiber such as silk, wool, cashmere; asbestos Such as mineral fiber. These materials may be used in combination of two or more. In addition, when steaming a large-sized plated steel sheet (for example, a plated steel sheet having a width of 500 mm and a length of 500 mm or more), use a planar spacer made of synthetic fibers that do not absorb moisture, such as polypropylene and polyethylene terephthalate. Is preferred. As described above, when a planar spacer made of natural fibers or the like that absorbs moisture is used, the natural fibers absorb water vapor and form a water film between the plated steel sheets. This is because there is a possibility that will not reach.

  The material of the planar spacer is preferably selected as appropriate according to the temperature of the steam treatment. Specifically, the material of the planar spacer preferably has a melting point exceeding the temperature of the steam treatment, and more preferably has a melting point higher by 30 ° C. or more than the temperature of the steam treatment. This is because when the melting point of the material of the planar spacer is equal to or lower than the temperature of the steam treatment, the planar spacer is thermally fused during the steam treatment, and the steam may not reach the center of the plated steel sheet.

  The shape of the planar spacer is not particularly limited. For example, the planar spacer may be a plate having a constant thickness. Further, as shown in FIG. 3, the planar spacer may have a shape in which a plurality of concave portions are arranged in a lattice shape. FIG. 3 is a photograph showing an example of a nonwoven fabric (planar spacer) made of synthetic fibers. FIG. 3A is a photograph of a planar spacer when viewed in plan. FIG. 3B is a photograph of a cross-section of part A shown in FIG. 3A. FIG. 3C is an enlarged photograph of the broken line part of FIG. 3B. FIG. 3D is a photograph of a cross section of part B shown in FIG. 3A.

  The thickness of the planar spacer is not particularly limited. When the planar spacer is thick, water vapor easily penetrates to the center of the plated steel sheet. Processing costs. On the other hand, when the thickness of the planar spacer is thin, there is a possibility that water vapor cannot sufficiently penetrate to the center of the plated steel sheet. The thickness of the planar spacer is usually about 0.06 to 2.0 mm.

  In particular, when steam processing is performed on a large-sized plated steel sheet (for example, a plated steel sheet having a width of 500 mm × a length of 500 mm or more), the thickness of the planar spacer is from the viewpoint of sufficiently reaching the central portion of the plated steel sheet. , 0.30 mm or more is preferable. Also in this case, the interval between the plated steel plates is preferably 0.05 mm or more from the viewpoint of allowing water vapor to easily enter.

Further, when steam treatment is performed on a plated steel sheet having a large size (for example, a plated steel sheet having a width of 500 mm × a length of 500 mm or more), the air permeability of the planar spacer is preferably 30 cc / cm ² / s or more. In order to increase the air flow rate of the planar spacer, it is effective to reduce the fiber density. However, it should be noted that if the fiber density is lowered too much, the tensile strength of the planar spacer is lowered, and it becomes easy to tear. From the viewpoint of air flow rate and tensile strength, the fiber density of the planar spacer is usually preferably in the range of 120 to 500 g / cm ² .

  Although the magnitude | size of a planar spacer is not specifically limited, It is preferable that it is a magnitude | size more than the plated steel plate which carries out a steam process. If a small planar spacer is disposed at the center of the plated steel plate, the peripheral portions of the plated steel plate come into contact with each other, which may cause unevenness in blackness.

  The method for arranging the planar spacer on the surface of the plated steel sheet is not particularly limited. When the plated steel plate is wound in a coil shape, the plated steel plate and the planar spacer may be wound in a coil shape. Moreover, what is necessary is just to laminate | stack a flat plate and a planar spacer alternately when a plated steel plate is a flat plate.

3. Third Step In a third step that is optionally performed before or after the second step, an inorganic coating or an organic resin coating is formed on the surface of the molten Al, Mg-containing Zn-plated steel sheet. The inorganic coating and the organic resin coating improve the corrosion resistance and galling resistance (retainability of black appearance) of the black-plated steel sheet.

[Inorganic coating]
The inorganic coating is one or more kinds selected from the group consisting of valve metal oxides, valve metal oxyacid salts, valve metal hydroxides, valve metal phosphates and valve metal fluorides. Those containing a compound (hereinafter also referred to as “valve metal compound”) are preferred. By including the valve metal compound, it is possible to provide an excellent barrier action while reducing the environmental load. Valve metal refers to a metal whose oxide exhibits high insulation resistance. Examples of the valve metal include one or more metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, W, Si, and Al. Known valve metal compounds may be used.

Moreover, a self-repairing action can be imparted by including a soluble fluoride of valve metal in the inorganic coating. The valve metal fluoride dissolves in the moisture in the atmosphere and then re-precipitates as a sparingly soluble oxide or hydroxide on the surface of the plated steel plate exposed from the film defect. fill in. In order to include the soluble fluoride of valve metal in the inorganic coating, the soluble fluoride of valve metal may be added to the inorganic coating, or soluble fluoride such as (NH ₄ ) F separately from the valve metal compound May be added.

  The inorganic film may further contain a soluble or hardly soluble metal phosphate or composite phosphate. Soluble phosphate elutes from the inorganic film to the film defect and reacts with the metal of the plated steel sheet to become insoluble phosphate, thereby complementing the self-repairing action of the valve metal with soluble fluoride. In addition, the hardly soluble phosphate is dispersed in the inorganic film to improve the film strength. Examples of the metal contained in the soluble metal phosphate or composite phosphate include alkali metals, alkaline earth metals, and Mn. Examples of the metal contained in the hardly soluble metal phosphate or the composite phosphate include Al, Ti, Zr, Hf, and Zn.

  The inorganic film can be formed by a known method. For example, an inorganic paint containing a valve metal compound or the like may be applied to the surface of the molten Al or Mg-containing Zn-plated steel sheet before or after contact with water vapor and dried without being washed with water. Examples of the coating method include a roll coating method, a spin coating method, and a spray method. When a valve metal compound is added to the inorganic paint, an organic acid having a chelating action may be added to the inorganic paint so that the valve metal compound can be stably present in the inorganic paint. Examples of organic acids include tannic acid, tartaric acid, citric acid, oxalic acid, malonic acid, lactic acid and acetic acid.

[Organic resin film]
The organic resin constituting the organic resin film is urethane resin, epoxy resin, olefin resin, styrene resin, polyester resin, acrylic resin, fluorine resin, or a combination of these resins, or these resins. Or a modified product thereof. By using these flexible organic resins, generation of cracks can be suppressed when forming a black-plated steel sheet, and corrosion resistance can be improved. Further, when the valve resin compound is included in the organic resin film, the valve metal compound can be dispersed in the organic resin film (organic resin matrix) (described later).

  The organic resin film preferably contains a lubricant. By including the lubricant, galling resistance can be improved. The type of the lubricant is not particularly limited and may be selected from known ones. Examples of the lubricant include organic waxes such as fluorine, polyethylene, and styrene, and inorganic lubricants such as molybdenum disulfide and talc.

  The organic resin film preferably contains the aforementioned valve metal compound, similarly to the inorganic film. By including the valve metal compound, it is possible to provide an excellent barrier action while reducing the environmental load.

  Further, the organic resin film may further contain a soluble or hardly soluble metal phosphate or composite phosphate, similarly to the inorganic film. Soluble phosphate is eluted from the organic resin film to the film defect portion and reacts with the metal of the plated steel sheet to become insoluble phosphate, thereby complementing the self-repairing action of the valve metal with soluble fluoride. Further, the hardly soluble phosphate is dispersed in the organic resin film to improve the film strength.

  When the organic resin film contains a valve metal compound or a phosphate, an interface reaction layer is usually formed between the plated steel sheet and the organic resin film. Interfacial reaction layer consists of zinc fluoride, zinc phosphate, valve metal fluoride, phosphoric acid, which is a reaction product of fluoride or phosphate contained in organic paint and metal or valve metal contained in plated steel sheet It is a dense layer made of salt. The interface reaction layer has an excellent environmental shielding ability and prevents corrosive components in the atmosphere from reaching the plated steel sheet. On the other hand, in the organic resin film, particles of valve metal oxide, valve metal hydroxide, valve metal fluoride, phosphate, and the like are dispersed in the organic resin matrix. Since particles such as valve metal oxide are three-dimensionally dispersed in the organic resin matrix, corrosive components such as moisture that have permeated the organic resin matrix can be captured. As a result, the organic resin film can greatly reduce the corrosive components reaching the interface reaction layer. An excellent anticorrosive effect is exhibited by the organic resin film and the interface reaction layer.

  For example, the organic resin film is a urethane resin film containing a urethane resin having excellent flexibility. The urethane-based resin constituting the urethane-based resin film is obtained by reacting a polyol and a polyisocyanate, but after forming the urethane-based resin film, when performing steam treatment to give a black color tone, the polyol is It is preferable to use an ether polyol (polyol containing an ether bond) and an ester polyol (polyol containing an ester bond) in combination at a predetermined ratio.

  When a urethane-based resin film is formed using only an ester-based polyol as a polyol, the ester bond in the urethane-based resin is hydrolyzed by water vapor, so that the corrosion resistance cannot be sufficiently improved. On the other hand, when a urethane-based resin film is formed using only an ether-based polyol as the polyol, the adhesion with the plated steel sheet is not sufficient, and the corrosion resistance cannot be sufficiently improved. In contrast, the present inventors use ether polyols and ester polyols in combination at a predetermined ratio, taking advantage of both and making up for the disadvantages, thereby significantly improving the corrosion resistance of the plated steel sheet. I found out that I could make it. According to this, even if a water vapor treatment is performed to give a black color tone after forming the urethane resin film (described later), the effect of improving the corrosion resistance by the urethane resin film can be maintained. That is, a black-plated steel sheet having a black color tone and excellent corrosion resistance can be produced.

  The kind of ether polyol is not particularly limited, and may be appropriately selected from known ones. Examples of the ether polyol include polyethylene glycol, polypropylene glycol, linear polyalkylene polyol such as ethylene oxide or propylene oxide adduct of glycerin, and the like.

  The kind of ester polyol is not particularly limited, and may be appropriately selected from known ones. For example, as the ester polyol, a linear polyester having a hydroxy group in the molecular chain obtained by reacting a dibasic acid and a low molecular polyol can be used. Examples of dibasic acids include adipic acid, azelaic acid, dodecanedioic acid, dimer acid, isophthalic acid, hexahydrophthalic anhydride, terephthalic acid, dimethyl terephthalate, itaconic acid, fumaric acid, maleic anhydride, Esters are included.

  The ratio of the ether-based polyol in the polyol composed of the ether-based polyol and the ester-based polyol is preferably in the range of 5 to 30% by mass. When the ratio of the ether-based polyol is less than 5% by mass, the ratio of the ester-based polyol is excessively increased, so that the urethane-based resin film is easily hydrolyzed, and the corrosion resistance may not be sufficiently improved. On the other hand, when the ratio of the ether-based polyol is more than 30% by mass, the ratio of the ether-based polyol is excessively increased, so that the adhesion with the plated steel sheet is lowered and the corrosion resistance may not be sufficiently improved. .

  The kind of polyisocyanate is not particularly limited, and may be appropriately selected from known ones. For example, a polyisocyanate compound having an aromatic ring can be used as the polyisocyanate. Examples of polyisocyanate compounds having an aromatic ring include hexamethylene diisocyanate, o-, m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 2 hydrogenated aromatic rings. , 4- or 2,6-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 3,3′-dimethyl-4,4′-biphenylene diisocyanate, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω , Ω′-diisocyanate-1,3-dimethylbenzene and the like. These may be used alone or in combination of two or more.

  The urethane resin film preferably further contains a polyhydric phenol. When the urethane-based resin film contains a polyhydric phenol, a concentrated layer of polyhydric phenol is formed at the interface between the plated steel plate and the polyhydric phenol to firmly adhere them. Therefore, the corrosion resistance of the urethane resin film can be further improved by blending polyhydric phenol into the urethane resin film.

  The kind of polyhydric phenol is not particularly limited, and may be appropriately selected from known ones. Examples of the polyhydric phenol include tannic acid, gallic acid, hydroquinone, catechol, and phloroglucinol. Moreover, the compounding quantity of the polyhydric phenol in a urethane type resin film has the preferable inside of the range of 0.2-30 mass%. When the blending amount of the polyhydric phenol is less than 0.2% by mass, the effect of the polyhydric phenol cannot be exhibited sufficiently. On the other hand, when the blending amount of the polyhydric phenol is more than 30% by mass, the stability of the paint may be lowered.

  The organic resin film may be a coating layer or a laminate layer. Moreover, it is preferable that an organic type resin film is a clear coating film from a viewpoint of utilizing the black external appearance of a black plating steel plate.

  The organic resin film can also be formed by a known method. For example, when the organic resin film is a coating layer, an organic paint containing an organic resin or a valve metal compound is applied to the surface of the molten Al, Mg-containing Zn-plated steel sheet before or after contacting with water vapor. What is necessary is just to apply | coat and to dry without washing with water. Examples of the coating method include a roll coating method, a spin coating method, and a spray method. When a valve metal compound is added to the organic paint, an organic acid having a chelating action may be added to the organic paint so that the valve metal compound can be stably present in the organic paint. When an organic paint containing an organic resin, valve metal compound, fluoride, phosphate, etc. is applied to the surface of the plated steel sheet, inorganic anions such as fluorine ions and phosphate ions and metal or valve metal contained in the plated steel sheet A film (interfacial reaction layer) consisting of a reaction product with the above is formed preferentially and densely on the surface of the plated steel plate, on which a valve metal oxide, a valve metal hydroxide, a valve metal fluoride, An organic resin film in which particles such as phosphate are dispersed is formed. On the other hand, when the organic resin film is a laminate layer, an organic resin film containing a valve metal compound or the like may be laminated on the surface of the plated steel sheet.

  By the above procedure, a black-plated steel sheet in which the surface of the plating layer is uniformly blackened can be efficiently produced without causing corrosion on the surface of the plating layer.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited by these Examples.

[Experiment 1]
In Experimental Example 1, the degree of blackening of the plated steel sheet treated with water vapor using various linear spacers and the occurrence of corrosion on the surface of the plated layer were examined.
1. Plated steel plate Using SPCC with a plate thickness of 1.2 mm as a base material, a molten Al, Mg-containing Zn plated steel plate with a plating layer thickness of 10 μm was prepared. At this time, the composition of the plating bath (concentration of Zn, Al, Mg, Si, and Ti) was changed to produce six types of plated steel sheets having different plating layer compositions (see Table 1). The composition of the plating bath and the composition of the plating layer are the same.

2. A wire rod (Tosun wire rope Co., Ltd.) having a diameter of 0.5 mm or 2 mm made of linear spacer SUS304 was prepared. Moreover, a wire rod (Chuko Kasei Kogyo Co., Ltd.) having a diameter of 0.5 mm or 2 mm made of a fluororesin was prepared. The SUS304 wire was coated with a fluororesin (Acecoat Co., Ltd.) as necessary. Using the prepared wires, 12 types of linear spacers shown in Table 2 were produced.

3. Production and Evaluation of Black Plated Steel Plate (1) Steam Treatment Using Linear Spacer Two 400 mm × 400 mm plated steel plates (upper plated steel plate, lower plated steel plate) were cut out from the original plate of the plated steel plate. As shown in FIG. 2A, four linear spacers were placed on the lower plated steel sheet so as to be located 15 mm inside from each side of the lower plated steel sheet. The upper plated steel sheet was laminated on the linear spacer, and pressure was applied so that the surface pressure was 1.5 kN / cm ² . In this state, the plated steel sheet was steam treated under the conditions of a steam temperature of 165 ° C., a relative humidity of 90%, and a treatment time of 1.5 hours.

(2) Measurement of degree of blackening The brightness (L ^* value) of the surface of the plating layer was measured for each plated steel sheet after the steam treatment. The lightness (L ^* value) of the plating layer surface was measured by a spectral reflection measurement method based on JIS K 5600 using a spectral color difference meter (TC-1800; Tokyo Denshoku Co., Ltd.). The measurement conditions are shown below.
Optical conditions: d / 8 ° method (double beam optical system)
Field of view: 2 degree field of view Measurement method: Reflected light measurement Standard light: C
Color system: CIELAB
Measurement wavelength: 380 to 780 nm
Measurement wavelength interval: 5 nm
Spectrometer: Diffraction grating 1200 / mm
Lighting: Halogen lamp (voltage 12V, power 50W, rated life 2000 hours)
Measurement area: 7.25mmφ
Detection element: Photomultiplier tube (R928; Hamamatsu Photonics Co., Ltd.)
Reflectance: 0-150%
Measurement temperature: 23 ° C
Standard plate: white

A. Measurement of lightness (L ^* value) of the center portion As shown in FIG. 2B, the lightness of the center portion (center) of the surface on which the spacers of the plated steel plate are arranged was measured. If the L ^* value of the center portion is less than or equal to 35 "◎", L ^* value of 40 or less was 35 more than "○", L ^* value of 60 or less and a greater than 40 "△", L ^{* When the} value exceeded 60, it was evaluated as “x”.

B. Measurement of difference in blackening degree (L ^* value) between the center part and the edge part As shown in FIG. 2B, the brightness of the center part and the edge part (position of 10 mm from the end part) on the surface where the spacer of the plated steel plate is arranged. It was measured. By subtracting the L ^* value of the center portion from the L ^* value of the edge portion, and calculates a difference between L ^* values of the edge portion and the center portion. “◎” when the difference in L ^* value between the edge portion and the center portion is 1.0 or less, “◯” when the difference in L ^* value is more than 1.0 and 5.0 or less, difference in L ^* value Was more than 5.0 and 10.0 or less, “Δ”, and when the L ^* value difference was more than 10.0, “×” was evaluated.

(3) Presence / absence of corrosion on the surface of the plated steel sheet About each plated steel sheet after the steam treatment, the presence / absence of corrosion of the part in contact with the linear spacer on the surface of the plating layer was evaluated visually. When the corrosion did not occur on the plating layer surface, it was evaluated as “◯”, and when corrosion occurred, it was evaluated as “x”.

4). Results Table 4 shows the types of the plated steel sheets and linear spacers used, the lightness (L ^* value) of the plating layer surface after the steam treatment, and the presence or absence of corrosion on the plating layer surface.

  From the results of Comparative Example 5 in Table 4, it can be seen that if the spacer is not used, water vapor cannot enter between the plated steel sheets and cannot be blackened. Moreover, it turns out that corrosion will generate | occur | produce on the surface of a plated steel plate from the result of Comparative Examples 1-4 if the metal wire which does not coat the surface with resin is used as a spacer. On the other hand, from the results of Examples 1 to 27, it is understood that when a spacer whose surface is made of an insulator (resin) is used, corrosion does not occur on the surface of the plated steel sheet.

In the black-plated steel plates of Examples 4, 8, 12, 16, 20, and 24 produced using a single-wire linear spacer, the L ^* value of the center portion did not reach the evaluation standard, and the edge portion and the center portion There was a difference in L ^* value (blackening degree). As shown in FIG. 2A, this is considered to be because the single-line linear spacers are arranged so as to surround the center portion of the plating layer surface without a gap. That is, the single-wire linear spacer is in contact with the plating layer without any gap, and the water vapor at the edge portion could not move to the center portion side, so it is considered that the center portion was not blackened. Although the experimental results are not shown here, the surface of the plated steel sheet is uniformly blackened by arranging two single-wire linear spacers in parallel so that the water vapor at the edge can move toward the center. can do.

  Black of Examples 1-3, 5-7, 9-11, 13-15, 17-19, 21-23, 25-27 produced using concentric stranded wire type, collective stranded wire type or knitted wire type linear spacers In the plated steel sheet, the linear spacer is disposed so as to surround the center portion of the plated layer surface without any gap, but the surface of the plated steel sheet can be uniformly blackened. This is presumably because a concentric stranded wire type, aggregated stranded wire type or knitted wire type linear spacer leaves a gap through which water vapor can pass between the linear spacer and the plating layer even if it contacts the plating layer. From these results, it can be seen that the concentric stranded wire type, collective stranded wire type or knitted wire type linear spacer is more preferable than the single wire type linear spacer.

[Experiment 2]
In Experimental Example 2, the degree of blackening of the plated steel sheet treated with water vapor using various planar spacers and the occurrence of corrosion on the surface of the plated layer were examined.
1. Plated steel sheets The same six types of plated steel sheets as in Experimental Example 1 were prepared.

2. Planar spacer A. Preparation of planar spacer As a planar spacer, Wipeall x70, Techno Power (all Nippon Paper Crecia Co., Ltd.), slip paper 40NN (Nippon Paper Industries Co., Ltd.) and Autocle 400 (Nippon Paper Papillia Co., Ltd.) were prepared (Table 5). reference).

B. Measurement of water absorption of each planar spacer In order to know the water vapor permeability of each planar spacer, the water absorption was measured for each planar spacer. The water absorption was measured under the conditions of an atmospheric temperature of 23 ° C. and a relative humidity of 50%. A test piece (10 cm × 10 cm) was cut out from the base paper. The test piece was immersed in 1 L of pure water for 15 minutes to allow the test piece to absorb pure water. The test piece taken out from the pure water was suspended for 1 minute to remove excess pure water that was not absorbed by the test piece. The water absorption weight (g / g) per unit weight of the test piece was calculated by dividing the water absorption weight obtained by subtracting the absolute dry weight of the test piece from the weight of the test piece after water absorption by the absolute dry weight of the test piece. Also, the amount of water absorption per unit area of the test piece (g / g ² ) is multiplied by the amount of water absorption (g / g) per unit weight of the test piece by the weight per unit area (g / m ² ) of each planar spacer. / M ² ) was calculated.

3. Production and Evaluation of Black Plated Steel Plate (1) Steam Treatment Using Planar Spacer Two 400 mm × 400 mm plated steel plates (upper plated steel plate, lower plated steel plate) were cut out from the original plate of the plated steel plate. As shown in FIG. 2C, a 400 mm × 400 mm planar spacer was laminated on one surface of the lower plated steel sheet. The upper plated steel sheet was laminated on the planar spacer, and pressure was applied so that the surface pressure was 1.5 kN / cm ² . In this state, the plated steel sheet was steam treated under the conditions of a steam temperature of 165 ° C., a relative humidity of 90%, and a treatment time of 1.5 hours.

(2) Measurement of the degree of blackening and evaluation of the presence or absence of corrosion For each plated steel sheet after the steam treatment, the degree of blackening (L ^* value) of the center part and the edge part is measured in the same procedure as in Experimental Example 1, and plating is performed. The presence or absence of corrosion at the spacer contact portion on the surface of the layer was evaluated.

4). Results Table 6 shows the types of the plated steel sheet and the planar spacer used, the lightness (L ^* value) of the plating layer surface after the steam treatment, and the presence or absence of corrosion on the plating layer surface.

  From the results of Examples 28 to 42 in Table 6, it can be seen that when a paper material made of an insulator (plant fiber or resin fiber) is used as a spacer, corrosion does not occur on the surface of the plated steel sheet.

As shown in Table 6, in the black-plated steel plates of Examples 30, 31, 34, 35, 38, and 39 manufactured using a planar spacer having a water absorption of less than 100 g / cm ² , the water vapor transmission amount is small. Therefore, the difference between the L ^* value of the center part and the L ^* value of the edge part and the center part was large to some extent. On the other hand, in the black-plated steel plates of Examples 28, 29, 32, 33, 36, 37 and 40 to 42 manufactured using a planar spacer having a water absorption of 100 g / cm ² or more, the water vapor transmission amount was sufficient. Therefore, the difference between the L ^* value of the center part and the L ^* value of the edge part and the center part was small.

[Experiment 3]
In Experimental Example 3, using various planar spacers, the degree of blackening of the plated steel sheet subjected to the steam treatment under conditions different from Experimental Example 2 and the occurrence of corrosion on the surface of the plating layer were examined.
1. Plated steel sheets The same six types of plated steel sheets as in Experimental Example 1 were prepared.

2. Planar Spacer The same planar spacer as in Experimental Example 2 was prepared.

3. Production and Evaluation of Black Plated Steel Plate (1) Steam Treatment Using Planar Spacer Two plated steel plates having a width of 400 mm and a length of 400 mm (upper plated steel plate, lower plated steel plate) were cut out from the original plate of the plated steel plate. As shown in FIG. 2C, a 400 mm × 400 mm planar spacer was laminated on one surface of the lower plated steel sheet. The upper plated steel sheet was laminated on the planar spacer, and pressure was applied so that the surface pressure was 1.5 kN / cm ² . In this state, the plated steel sheet was steam-treated under the conditions of a steam temperature of 142 ° C., a relative humidity of 87%, and a treatment time of 6 hours.

(2) Measurement of the degree of blackening and evaluation of the presence or absence of corrosion For each plated steel sheet after the steam treatment, the degree of blackening (L ^* value) of the center part and the edge part is measured in the same procedure as in Experimental Example 2, and plating is performed. The presence or absence of corrosion at the spacer contact portion on the surface of the layer was evaluated.

4). Results Table 7 shows the types of plated steel sheets and planar spacers used, the lightness (L ^* value) of the plating layer surface after the steam treatment, and the presence or absence of corrosion on the plating layer surface.

  From the results of Comparative Example 6 in Table 7, it can be seen that if the spacer is not used, water vapor cannot enter between the plated steel sheets and cannot be blackened. Moreover, it turns out that corrosion does not generate | occur | produce on the surface of a plated steel plate from the result of Examples 43-57, when a water vapor process is performed using a planar spacer.

  From the results of Experimental Example 2 and Experimental Example 3, the surface of the plating layer can be sufficiently blackened with any planar spacer depending on the conditions of the steam treatment. Moreover, when it blackens in a short time, it turns out that it is preferable to use a planar spacer with a high water absorption.

[Experimental Example 4]
In Experimental Example 4, the blackened degree of the plated steel sheet subjected to the steam treatment using various planar spacers and the occurrence of corrosion on the surface of the plated layer were examined for a larger-sized plated steel sheet.

1. Plated steel plate No. 1 plated steel sheet was prepared.

2. Planar Spacer As a planar spacer, No. 1 shown in Table 8 is used. 17 to 34 nonwoven fabrics were prepared. FIG. 3 is a photograph of the nonwoven fabric used. As shown in FIGS. 3A to 3D, the nonwoven fabric has a plurality of concave portions formed in a lattice shape. The air permeability of the nonwoven fabric was measured by the fragile method according to JIS L 1913.

3. Production and Evaluation of Black Plated Steel Plate (1) Steam Treatment Using Planar Spacer Two plated steel plates having a width of 800 mm and a length of 800 mm (upper plated steel plate, lower plated steel plate) were cut out from the original plate of the plated steel plate. As shown in FIG. 2C, No. 1 in Table 5 was formed on one surface of the lower plated steel sheet. 13 or no. 17 to 34 planar spacers (800 mm × 800 mm) were laminated. Furthermore, a plated steel plate was laminated on the upper side of the planar spacer to prepare a set of plated steel plates for evaluation. Then, pressure was applied so that the surface pressure was 1.5 KN / cm ² . In this state, a plurality of sets of plated steel sheets for evaluation were steam-treated under the two types of conditions shown in Table 9.

(2) Evaluation of degree of blackening A total of three test pieces randomly selected one by one from each set of plated steel sheets after steam treatment, the peripheral part (any 4 pieces located 20 mm inside from the end part) Lightness (L ^* value) at the center (1 sheet) and at the center (any 4 spots near the center / 1 sheet). The lightness measurement conditions are the same as in Experimental Example 1. An average value was calculated for each of the brightness of the peripheral part of the selected three plated steel sheets and the brightness of the central part of the selected three plated steel sheets. The ΔL ^* value calculated by subtracting the average value of the L ^* values in the central portion from the average value of the L ^* values in the peripheral portion was used as an index for evaluating the blackening uniformity. For each specimen, if the ΔL ^* value is 5 or less, “◎”; Was evaluated as “×”. Table 10 shows the evaluation results.

(3) Evaluation of corrosion resistance Corrosion resistance was evaluated about each plated steel plate after a steam process. Corrosion resistance is the area where red rust is generated after sealing the end face of a test piece (width 70 mm x length 150 mm) cut from each plated steel sheet, followed by a salt spray process, a drying process and a wetting process in one cycle (8 hours). The number of cycles until the rate reached 5% was evaluated. The salt water spraying process was performed by spraying a 5% NaCl aqueous solution at 35 ° C. on the test piece for 2 hours. The drying process was performed by leaving it to stand for 4 hours in an environment with an air temperature of 60 ° C. and a relative humidity of 30%. The wetting process was performed by leaving it for 2 hours in an environment of an air temperature of 50 ° C. and a relative humidity of 95%. Evaluated as “◎” when the number of cycles until the area ratio of red rust reaches 5% exceeds 70 cycles, “◯” when 30 cycles or more and 70 cycles or less, and “X” when less than 30 cycles. did.

  Table 10 shows the results of evaluation of the brightness and corrosion resistance of the surface of the plating layer of each test piece after the steam treatment.

As shown in Table 10, the corrosion resistance of all the test pieces was good. In the black plated steel sheets of Comparative Examples 7 and 8 manufactured without sandwiching the planar spacer, water vapor could not enter between the plated steel sheets and could not be blackened. In the black plated steel plates of Examples 58 and 77 manufactured using a planar spacer made of pulp and polypropylene, the planar spacer absorbs water, thereby forming a water film between the black plated steel plates. Since it was difficult for water vapor to reach the central part of the steel plate, it was not possible to sufficiently blacken in this treatment time. In the black-plated steel plates of Examples 59, 60, 68, 69, 87, and 88 manufactured using a planar spacer having a thickness of less than 0.3 mm, water vapor is generated up to the central portion of the plated steel plate due to insufficient thickness of the planar spacer. Since it was difficult to reach, it was not possible to sufficiently blacken in this processing time. In the black-plated steel plates of Examples 65, 66, 74, 75, 93, and 94 manufactured using spacers having an air flow rate of less than 30 cc / cm ² / s, water vapor was generated up to the central portion of the plated steel plate due to insufficient air flow rate. Since it was difficult to reach, it was not possible to sufficiently blacken in this processing time. In addition, in the black-plated steel plates of Examples 78 to 86 manufactured using a polypropylene planar spacer having a melting point of 160 ° C., it was not possible to sufficiently blacken even though the planar spacer was used. . As shown in FIGS. 4A and 4B, this is thought to be because the planar spacers were thermally fused and hindered by the ingress of water vapor. FIG. 4A is a photograph of a cross-section of a polypropylene planar spacer (melting point: 160 ° C.) before steaming. FIG. 4B is a photograph of a cross section of a planar spacer made of polypropylene after steaming at 150 ° C. As shown in FIG. 4B, thermal fusion was observed when a nonwoven fabric made of synthetic fibers having a melting point 10 ° C. higher than the temperature of the steam treatment was used.

On the other hand, Examples 61, 62, 63, 64, 67, 70, 71, 72, and 73 manufactured using a polyethylene terephthalate planar spacer having a thickness of 0.3 mm or more and an air flow rate of 30 cc / cm ² / s or more. 76, the plated steel sheet could be blackened uniformly. FIG. 4C is a photograph of a cross section of a polyethylene terephthalate planar spacer (melting point 250 ° C.) after steam treatment at 150 ° C. As shown in FIG. 4C, when a non-woven fabric made of synthetic fibers having a melting point 100 ° C. higher than the temperature of the steam treatment was used, no thermal fusion was observed.

From these results, the use of a planar spacer made of a material having a thickness of 0.3 mm or more and an air flow rate of 30 cc / cm ² / s or more and having a melting point sufficiently higher than the temperature of the steam treatment, Even so, it can be seen that it can be uniformly blackened in a short time.

  The method for producing a black-plated steel sheet according to the present invention can efficiently produce a black-plated steel sheet without causing corrosion on the surface of the plating layer. For example, a roofing material or exterior material of a building, a home appliance, an automobile, etc. It is useful as a method for producing a black-plated steel sheet used in the above.

Claims (5)

Al: 0.1 to 22.0 mass%, Mg: molten Al containing 0.1 to 10.0 mass%, a molten Al having an Mg-containing Zn plating layer, a step of preparing an Mg-containing Zn-plated steel sheet,
Between the molten Al and Mg-containing Zn-plated steel sheets arranged in a coiled or flat laminate, the molten Al and Mg are covered with an insulator or a spacer made of an insulator is arranged. A step of bringing the Zn-plated steel sheet into contact with water vapor;
A method for producing a black-plated steel sheet.   The method of manufacturing a black-plated steel sheet according to claim 1, wherein the spacer is made of a metal wire coated with a resin, a resin wire, or a combination thereof.   The method for producing a black-plated steel sheet according to claim 2, wherein the spacer is a concentric stranded wire, a collective stranded wire or a knitted wire made of a metal wire coated with a resin, a resin wire, or a combination thereof.   The said spacer is a manufacturing method of the black plating steel plate of Claim 1 which is paper, cloth, or a nonwoven fabric. The size of the molten Al, Mg-containing Zn plated steel sheet is 500 mm wide x 500 mm long,
The spacer is a non-woven fabric made of synthetic fiber and having a thickness of 0.3 mm or more and an air permeability of 30 cc / cm ² / s or more.
The manufacturing method of the black plating steel plate of Claim 1.