Title of invention: Surface-treated steel sheet Technical field [0001] 　The present invention relates to a surface-treated steel sheet having high corrosion resistance and excellent blackening resistance. Background technology [0002] 　Plated steel sheets such as galvanized steel sheets, which have excellent corrosion resistance and blackening resistance, are widely used for home appliances, building materials, automobiles, and the like. [0003] 　The surface of various plated steel sheets such as galvanized steel sheets may deteriorate depending on the surrounding environment. For example, the plating layer is oxidized by electrolytes such as salts contained in the atmosphere, oxygen and moisture existing in a high temperature and high humidity environment, and white rust is generated. When white rust is generated, the appearance uniformity of the plated steel sheet is impaired. Therefore, the plated steel sheet is generally required to have corrosion resistance that suppresses the generation of white rust. [0004] 　In particular, when galvanized steel sheets are used outdoors, such as for building materials and outdoor home appliances, they are more susceptible to the influence of the surrounding environment and are more likely to deteriorate over time, so high corrosion resistance is required. [0005] 　As a technique for further improving the corrosion resistance of galvanized steel sheets, steel sheets plated with Zn-based alloys such as Zn—Al—Mg-based alloy plating are known. [0006] 　Both short-term corrosion resistance and long-term corrosion resistance are required for Zn-based alloy-plated steel sheets. "Short-term corrosion resistance" means, for example, that the builder does not corrode during the period (about one year) until the plated steel sheet is delivered to the orderer, and "long-term corrosion resistance" means, for example, a product for building materials. It means that the wall is thinned by corrosion and the period until the required strength is not obtained is as long as possible. [0007] 　Another characteristic required for Zn-based alloy-plated steel sheets is blackening resistance. Blackening means that the plating layer oxidizes and turns black. Blackening is particularly noticeable in Zn—Al alloy plated steel sheets and Zn—Al—Mg alloy plated steel sheets in which Al or Mg is added during galvanizing. It is not preferable in use that the discoloration of the plated steel sheet is visually visible from the appearance due to the blackening of the plating layer. Therefore, a Zn-based alloy-plated steel sheet such as a Zn-Al-Mg-based alloy-plated steel sheet is required to have excellent blackening resistance while having corrosion resistance. [0008] 　Patent Document 1 includes a steel sheet, a Zn—Al—Mg-based alloy plating layer formed on the surface of the steel sheet, and an aluminum-containing film formed on the alloy plating layer, and is excellent in blackening resistance and corrosion resistance. Galvanized steel sheets are disclosed. [0009] 　Further, Patent Document 2 discloses a chromate-free coated metal plate having a coating film containing an organic resin as a film-forming component and a flake-shaped aluminum pigment whose surface has been inactivated on at least one surface of the metal plate. It is taught that such a metal plate is excellent in corrosion resistance and blackening resistance. [0010] 　Further, in Patent Document 3, a steel plate and a plated steel sheet having a plating layer arranged on the surface of the steel sheet and a chemical conversion treatment film arranged on the surface of the plating layer are provided, and the chemical conversion treatment film is a fluororesin and a base material. Chemical-treated steel sheets containing resins, metal flakes, and chemical conversion-treated components are disclosed, and it is taught that the use of such steel sheets can improve corrosion resistance and blackening resistance. Prior art literature Patent documents [0011] Patent Document 1: International Publication No. 2015/075792 Patent Document 2: International Publication No. 2013/065354 Patent Document 3: Japanese Patent Application Laid-Open No. 2016-121390 Outline of the invention Problems to be solved by the invention [0012] 　However, in the Zn—Al—Mg based alloy plated steel sheet described in Patent Document 1, a part of the aluminum pigment in the film protrudes from the surface of the film after production or when the surface of the film is thinned due to deterioration of the resin. May be done. Then, starting from the protruding pigment, a path through which a corrosive factor such as oxygen can pass through the film is formed, and as a result, the corrosive factor invades the underlying plating layer through the path and the plating layer. Corrosion may progress. Therefore, there is room for improvement in corrosion resistance. Further, in Patent Document 1, the concentration distribution of the aluminum pigment in the film has not always been sufficiently studied, and there is still room for improvement in the blackening resistance. [0013] 　Further, in Patent Documents 2 and 3, the control of the concentration distribution of the flake-shaped aluminum or the like pigment is not always sufficiently examined, and there is still room for improvement in the blackening resistance. [0014] 　In view of the above problems, an object of the present invention is to provide a surface-treated steel sheet having high corrosion resistance and excellent blackening resistance in a Zn-based alloy-plated steel sheet. Means to solve problems [0015] 　In order to obtain a surface-treated steel sheet having such high corrosion resistance and excellent blackening resistance, the present inventors use a coloring pigment such as an aluminum pigment in a coating film formed on a Zn-based alloy plating layer. It has been found that it is important to control the average concentration to 5 to 15% by mass. With such control, the coloring pigment sufficiently covers the Zn-based alloy plating layer when observed from a direction perpendicular to the surface of the coating film, so that the coloring pigment makes the blackening of the Zn-based alloy plating layer invisible. As a result, changes in appearance can be suppressed and excellent blackening resistance can be obtained. [0016] 　The present inventors have also found that it is important to concentrate the coloring pigment on the Zn-based alloy plating layer side in the coating film. By thickening the coloring pigment on the Zn-based alloy plating layer side in this way, it is possible to suppress the coloring pigment from protruding from the surface of the coating film, thereby suppressing the formation of paths of corrosion factors and ensuring corrosion resistance. can do. Further, by thickening the coloring pigment on the Zn-based alloy plating layer side, the coloring pigment can be arranged in a narrow region in the coating film and at a closer distance to each other. Therefore, the coloring pigment can be distributed at a high density in the coating film, and the Zn-based alloy plating layer in a wider range can be effectively made invisible, and as a result, the blackening resistance is improved. [0017] 　The present invention has been made based on the above findings, and the gist thereof is as follows. 　(1) An 　average thickness T 1 formed on a steel sheet, a Zn-based alloy plating layer formed on at least one surface of the steel sheet, and the Zn-based alloy plating layer, which contains a coloring pigment, a rust preventive pigment, and a binder resin. The 　chemical composition of the Zn-based alloy plating layer is, in terms of mass%, 　Al: 0.01 to 60%, 　Mg: 0.001 to 10%, and 　Si: 0 to 2%. 　The average concentration of the coloring pigment in the 　coating film is 5 to 15% in mass%, and the average of the coloring pigments present in a region having a width T 2 from the surface of the coating film in the thickness direction of the coating film. concentration C A1 and the from the Zn alloy plating layer side of the interface of the coating width T in the thickness direction of the coating film 2 average concentration C of the colored pigment present in the region of the A2 ratio of C A1 / C A2 Is 0.2 to 0.9, and 　T 2 (μm) = 0.1 × T 1A surface-treated steel sheet having a size of (μm) +1.1 μm. 　(2) 　The average concentration of the rust preventive pigment in the 　coating film is 3 to 12% in mass%, and is present in a region having a width T 2 from the surface of the coating film in the thickness direction of the coating film. The average concentration C B1 of the rust preventive pigment and the average concentration C B2 of the rust preventive pigment existing in the region of the width T 2 in the thickness direction of the coating film from the interface on the Zn-based alloy plating layer side of the coating film . The ratio C B1 / C B2 is 1.3 to 4.0, 　T 2 (μm) = 0.1 × T 1 (μm) + 1.1 μm, and the 　rust preventive pigments are Si, Mo, W and The surface-treated steel sheet according to (1), which comprises one type or two or more types of Ba. 　(3) The 　coloring pigment has a major axis X 1 of 5 to 30 μm, a minor axis X 2 of 1 to 30 μm, and a thickness X 3 of 0.0025 μm or more, and an average particle size = (X). When 1 + X 2 ) / 2 and the average aspect ratio = (X 1 + X 2 ) / 2 X 3 , the average particle size of the coloring pigment is 7 to 30 μm, and the average aspect ratio is 20 or more. The surface-treated steel sheet according to (1) or (2), which is characteristic. 　(4) The surface-treated steel sheet according to any one of (1) to (3), 　wherein the average thickness T 1 of the coating film is 3 to 15 μm. 　(5) The surface-treated steel sheet according to any one of (1) to (4), 　wherein the color pigment has a thickness of 0.5 T 1 or less. The invention's effect [0018] 　According to the present invention, the average concentration of the coloring pigment in the coating film is 5 to 15% in mass%, and the coloring pigment is concentrated on the Zn-based alloy plating layer side in the coating film. , To prevent the coloring pigment from protruding from the coating film to form a corrosive factor path, and to make the Zn-based alloy plating layer sufficiently invisible when observed from a direction perpendicular to the surface of the coating film. It is possible to provide a surface-treated steel plate having high corrosion resistance and excellent blackening resistance. In particular, the surface-treated steel sheet according to the present invention has high corrosion resistance and resistance even when the thickness of the coating film is reduced because the coloring pigment in the coating film is concentrated on the Zn-based alloy plating layer side. Black denaturation can be provided. Mode for carrying out the invention [0019] 　[Surface-treated steel sheet] 　The surface-treated steel sheet according to the present invention is formed on a steel sheet, a Zn-based alloy plating layer formed on at least one surface of the steel sheet, and a Zn-based alloy plating layer, and is formed on a coloring pigment, a rust preventive pigment, and a binder. It has a coating film with an average thickness of T 1 containing resin, and the chemical composition of the Zn-based alloy plating layer is mass%, Al: 0.01 to 60%, Mg: 0.001 to 10%, and Si. : 0 to 2%, the average concentration of the coloring pigment in the coating film is 5 to 15% in mass%, and exists in a region having a width T 2 from the surface of the coating film in the thickness direction of the coating film. the average concentration C of the colored pigment A1 and, from the Zn alloy plating layer side of the interface of the coating film thickness direction in a width T of the coating film 2 average concentration C of the coloring pigment present in the region A2 ratio C of the A1 / C A2 is 0.2 to 0.9, and T 2 (μm) = 0.1 × T 1 (μm) + 1.1 μm. Hereinafter, the constituent requirements of the surface-treated steel sheet according to the present invention will be described. [0020] 　 　The steel plate (plated original plate) in the present invention is not particularly limited, and a general steel plate such as a hot-rolled steel plate or a cold-rolled steel plate can be used. The steel type is not particularly limited, and for example, Al killed steel, ultra-low carbon steel containing Ti, Nb, etc., and high-strength steel containing elements such as P, Si, Mn, etc. can be used. is there. The thickness of the steel plate in the present invention is not particularly limited, but may be, for example, 0.25 to 3.5 mm. [0021] 　 　The Zn-based alloy plating layer in the present invention is formed on a steel sheet. The Zn-based alloy plating layer may be formed on one side of the steel sheet or on both sides. The Zn-based alloy plating layer may be a Zn—Al—Mg alloy plating layer containing at least Al and Mg, or may be a Zn—Al—Mg—Si alloy plating layer containing Si. Each of these contents (concentration) is mass%, Al: 0.01 to 60%, Mg: 0.001 to 10%, and Si: 0 to 2%, and the balance is Zn and impurities. Hereinafter, when the chemical composition of the Zn-based alloy plating layer is simply described as "%", it means "mass%". [0022] 　If the Al content of the Zn-based alloy plating layer is less than 0.01%, the effect of improving the corrosion resistance of the plated steel sheet due to the inclusion of Al is not sufficiently exhibited, and if it exceeds 60%, the effect of improving the corrosion resistance is saturated. Therefore, the Al content may be 0.01% or more, for example, 0.1% or more, 0.5% or more, 1% or more, 3% or more or 5% or more, and 60% or less, for example. , 55% or less, 50% or less, 40% or less, or 30% or less. The Al content is preferably 1 to 60%, more preferably 5 to 60%. [0023] 　If the Mg content of the Zn-based alloy plating layer is less than 0.001%, the effect of improving the corrosion resistance of the plated steel sheet due to the inclusion of Mg may not be sufficiently exhibited. On the other hand, if it exceeds 10%, Mg cannot be completely dissolved in the plating bath and floats as an oxide (generally called dross), and when galvanized in this plating bath, the oxide adheres to the plating surface layer and causes poor appearance, or , There is a risk that unplated parts (generally called non-plating) will occur. Therefore, the Mg content may be 0.001% or more, for example, 0.01% or more, 0.1% or more, 0.5% or more, 1% or more or 2% or more, and 10% or less. For example, it may be 8% or less, 6% or less, 5% or less, or 4% or less. The Mg content is preferably 1 to 5%, more preferably 1 to 4%. [0024] 　The lower limit of the Si content of the Zn-based alloy plating layer may be 0%, but it may be 0.001% to 2% in order to further improve the corrosion resistance of the Zn-based alloy plating layer. The Si content may be, for example, 0.005% or more, 0.01% or more, 0.05% or more, 0.1% or more or 0.5% or more, and 1.8% or less. It may be 1.5% or less or 1.2% or less. The Si content is preferably 0.1 to 2%, more preferably 0.5 to 1.5%. [0025] 　The Zn-based alloy plating layer in the present invention can be formed by a known plating method such as hot-dip galvanizing or thin-film deposition plating. For example, the thickness of the Zn-based alloy plating layer may be 1 to 30 μm. [0026] 　 　The coating film in the present invention is formed on a Zn-based alloy plating layer. In addition to the coloring pigment, the coating film contains a rust preventive pigment and a binder resin. The average thickness T 1 of the coating film may be any value as long as sufficient corrosion resistance and blackening resistance are ensured, but is preferably 3 μm or more and 15 μm or less, for example. If the average thickness T 1 of the coating film is less than 3 μm, there is a possibility that a part of the coloring pigment protrudes from the coating film and the corrosion factor reaches the alloy plating layer, and sufficient corrosion resistance cannot be guaranteed. .. Further, the thickness is insufficient to ensure the effect of obscuring the Zn-based alloy plating layer by the coloring pigment in the coating film, and the blackening resistance may be deteriorated. Further, when the average thickness T 1 of the coating film is more than 15 μm, the effect of improving the corrosion resistance and the blackening resistance by increasing the average thickness of the coating film is saturated. The average thickness T 1 of the coating film may be, for example, 4 μm or more, 5 μm or more, or 6 μm or more, and may be 12 μm or less or 10 μm or less. Therefore, the average thickness T 1 of the coating film is more preferably 3 μm or more and 12 μm or less. In addition, in this specification, "blackening resistance" does not mean that blackening of the Zn-based alloy plating layer under the coating film is suppressed, and even if blackening occurs in the Zn-based alloy plating layer. It means that the blackening is not visible from the outside by the coloring pigment in the coating film, and the surface-treated steel sheet is not changed in appearance. [0027] 　As used herein, "average thickness T 1 " refers to any of five locations on the interface of the coating film on the Zn-based alloy plating layer side by observing the cross section of the steel sheet having the coating film with a microscope. It is defined as a value obtained by measuring the shortest distance from each position to the surface of the coating film and averaging those measured values. When the coating film contains a substance having a particle size larger than the film thickness (for example, aggregate), the distance is measured at a position where the substance does not exist. This is because the presence of such a substance may cause the above distance to be measured larger than the actual thickness of the coating film when the coating film is observed from the cross-sectional direction. Further, another layer such as a chemical conversion treatment layer may be present between the Zn-based alloy plating layer and the coating film. If such another layer is present, the thickness of that layer is not included in the average thickness T 1 . [0028] 　(Coloring Pigment) As the coloring pigment in the 　present invention, for example, a general coloring pigment such as titanium oxide, zinc oxide, iron oxide, aluminum oxide, barium sulfate, aluminum, or carbon black can be used. Preferably, the color pigment is aluminum. However, aluminum reacts with water and elutes. Therefore, when a water-based paint is used as a paint for forming a coating film as in the present invention, it is necessary to coat aluminum with an oxide or a resin. [0029] 　The average concentration (average content) of the coloring pigment in the coating film is 5 to 15% by mass. By setting the average concentration of the coloring pigment in such a range and concentrating the coloring pigment near the interface with the Zn-based alloy plating layer, the film thickness is relatively thinner than that of a general coated steel sheet. Even if there is, the amount of the coloring pigment sufficiently covering the Zn-based alloy plating layer when observed from the direction perpendicular to the surface of the coating film can be secured. Further, it is possible to sufficiently suppress the coloring pigment from protruding from the surface of the coating film. Therefore, while maintaining high corrosion resistance, the coloring pigment makes the blackening of the Zn-based alloy plating layer invisible, whereby changes in appearance can be suppressed and excellent blackening resistance can be obtained. If the average concentration of the coloring pigment in the coating film is less than 5%, the density of the coloring pigment in the coating film for making the blackening of the Zn-based alloy plating layer invisible is insufficient, and the blackening resistance is lowered. On the other hand, if the average concentration of the coloring pigment in the coating film is more than 15%, a large amount of the coloring pigment is present in the coating film, and when the coating film is thinned, a part of the coloring pigment is released at a relatively early stage. There is a high possibility that it will protrude from the surface of the coating film, and the corrosion resistance may deteriorate. Further, the adhesion may be lowered. The average concentration of the color pigment in the coating film may be 6% or more, 7% or more, and may be 12% or less or 10% or less. The average concentration of the color pigment in the coating film is preferably 5 to 12%, more preferably 5 to 10%. [0030] 　As used herein, the "average concentration of colored pigments in a coating" is measured using a glow discharge emission surface analyzer (Glow Discharge Optical Measurement GD-OES). Specifically, when the type of the coloring pigment, that is, the specific compound of the coloring pigment is known, the coating film is sputtered from the surface toward the plating layer to deepen the main elements constituting the coloring pigment. The vertical density profile is measured every 1.0 μm. Then, the average value of the measured concentrations of the main elements is obtained, the measured concentration is converted based on the molecular weight of the compound of the known coloring pigment, and the average concentration of the coloring pigment in the coating film is obtained. When the type of coloring pigment, that is, the specific compound of the coloring pigment is unknown, the field emission type electron probe microanalyzer (Field Emission-Electron Probe) is applied to the coloring pigment from the cross section of the coating film (the surface perpendicular to the surface of the coating film). After specifying the type of the coloring pigment by element analysis using Micro Analyzer (FE-EPMA), the "average concentration of the coloring pigment in the coating film" may be measured as described above. [0031] 　The colored pigment in the coating film is concentrated on the Zn-based alloy plating layer side. The index of the concentration of the coloring pigment is from the interface between the average concentration C A1 of the coloring pigment existing in the region of the width T 2 in the thickness direction of the coating film from the surface of the coating film and the Zn-based alloy plating layer side of the coating film. It is determined by the ratio C A1 / C A2 of the color pigment existing in the region of the width T 2 in the thickness direction of the coating film to the average concentration C A 2 . The ratio C A1 / C A2 of the surface-treated steel sheet according to the present invention is 0.2 or more and 0.9 or less. Here, the width T 2 is determined by the following formula: T 2 (μm) = 0.1 × T 1 (μm) + 1.1 μm. That is, the width T 2 of the measurement region of the average concentrations C A 1 and CA 2 of the coloring pigment is determined according to the value of the average thickness T 1 of the coating film . More specifically, as described above, the average thickness of the coating film T 1 is observed from the cross-sectional observation of the coating film. Is determined, the width T 2 of the measurement region of CA 1 and CA 2 is determined from the above formula based on the T 1 , and the average concentration C A 1 and CA 2 of the coloring pigment is measured within the width T 2 . .. Incidentally, C A1 and region determining, C A2 if the the area to determine the overlap (i.e., T 2 > 0.5 T 1 even if it is), C as described above A1 and C A2 to It can be measured and the ratio C A1 / C A2 can be determined. When T 2 > T 1 (for example, when T 1 = 1.2 μm), such a surface-treated steel sheet is not included in the scope of the present invention. [0032] 　The ratio C A1 / C A2 of the surface-treated steel sheet according to the present invention is 0.2 or more and 0.9 or less. When this ratio C A1 / C A2 is less than 0.2, the rust preventive pigment becomes relatively thick on the surface side of the coating film, and when the coating film is thinned, the rust preventive pigment takes a relatively short time. A layer with a low concentration of is exposed, and sufficient long-term corrosion resistance cannot be obtained. On the other hand, when the ratio C A1 / C A2 exceeds 0.9, the effect of thickening the coloring pigment cannot be obtained, a part of the coloring pigment protrudes from the coating film, and the corrosion resistance becomes insufficient. Further, when the coating film is thinned, the concentration of the coloring pigment in the coating film is insufficient, so that the Zn-based alloy plating layer cannot be effectively made invisible, and the blackening resistance becomes insufficient. The CA1 / CA2 ratio may be, for example, 0.3 or more or 0.4 or more, and may be 0.8 or less or 0.7 or less. The C A1 / C A2 ratio is preferably 0.3 or more and 0.8 or less, and more preferably the C A1 / C A2 ratio is 0.4 or more and 0.7 or less. [0033] 　" Average concentration C A1 of the coloring pigment existing in the region of width T 2 from the surface of the coating film in the thickness direction of the coating film" and "From the interface on the Zn-based alloy plating layer side of the coating film in the thickness direction of the coating film The " average concentration CA2 of the coloring pigment existing in the region of the width T 2 " is measured by using GD-OES in the same manner as the measurement of the "average concentration of the coloring pigment in the coating film". Specifically, sputtering is performed from the surface direction of the coating film in the depth direction of the Zn-based alloy plating layer, and the concentration distribution in the depth direction of the coating film is widened by 0.1 μm for the main elements constituting the coloring pigment. Measure in the range of T 2 . Then, the average value of the measured concentrations of the main elements is obtained, the measured concentration is converted based on the molecular weight of the compound of the known coloring pigment, and the average concentration of the coloring pigment in the coating film is obtained. By measuring the relationship between the sputtering time and the coating film depth in advance, the sputtering time can be converted into the coating film thickness information. C A1 and C A2 can be obtained by measuring the concentration distribution of the elements constituting the coloring pigment in the film thickness direction . [0034] By thickening 　the colored pigment in the coating film on the Zn-based alloy plating layer side in the coating film so that the above-mentioned ratio C A1 / CA2 value is 0.2 or more and 0.9 or less in the coating film. , The color pigment concentration on the surface side of the coating film is relatively low. As a result, it is possible to prevent a part of the coloring pigment from protruding from the surface of the coating film after production or when the surface of the coating film is thinned. Therefore, it is possible to suppress the generation of a passage path for the corrosion factor, so that high corrosion resistance can be ensured. Further, by lowering the concentration of the coloring pigment on the surface side of the coating film, when the surface of the coating film is thinned, the coloring pigment is suppressed from falling off, and the blackening resistance is maintained for a long period of time. Therefore, under the condition that the average concentration of the coloring pigment in the coating film is constant, the surface-treated steel sheet according to the present invention has a Zn-based alloy plating layer as compared with the case where the coloring pigment is uniformly distributed in the coating film. It can be effectively invisible from the outside, thus significantly improving blackening resistance. In addition to this, another advantage of the color pigments being distributed over a narrow area is that when using pigments with orientations that have a high average aspect ratio (eg, scaly, flat, etc.), the color pigments The orientation can be aligned parallel to or substantially parallel to the surface of the coating film, and the plating layer can be more effectively made invisible and the blackening resistance can be improved. [0035] 　The colored pigment according to the present invention can have any shape as long as sufficient corrosion resistance and blackening resistance are ensured, but the shape of the colored pigment is, for example, not limited to spherical, elliptical, needle-shaped, and so on. Examples include flat, thin plate, scaly, and spindle-shaped. The colored pigment in the present invention is preferably scaly in order to more effectively obscure the Zn-based alloy plating layer and obtain excellent blackening resistance. [0036] 　When used in the present specification, the "average particle size" and "average aspect ratio" of the coloring pigment according to the present invention are determined by the following methods. First, any one coloring pigment is elementally mapped from the surface by FE-EPMA, and the major axis X 1 and the minor axis X 2 of the coloring pigment are obtained . Here, the major axis X 1 means the length of the maximum line segment that crosses the colored pigment within the contour of the image of the colored pigment specified by the element mapping, and the minor axis X 2 means the colored pigment. It means the length of a line segment perpendicular to the major axis X 1 that traverses . Next, element mapping is performed by FE-EPMA from the cross-sectional direction, and the value of the thickness X 3 (generally, the dimension in the direction perpendicular to the measurement plane of the major axis and the minor axis described above) is measured. Next, from these measured values, the particle size of the coloring pigment = [(X 1 + X 2 ) / 2] and the aspect ratio = [(X 1 + X 2 ) / 2X 3 ] are obtained. Then, the particle size and the aspect ratio of any 10 or more colored pigments are obtained by using the same method, and the "average particle size" and the "average aspect ratio" of the colored pigments are obtained by averaging each of them. [0037] 　The major axis X 1 , minor axis X 2 and thickness X 3 of the coloring pigment according to the present invention can be any value as long as they can be present in the coating film. For example, the major axis X 1 is 5 μm or more and 30 μm or less. The minor axis X 2 is 1 μm or more and 30 μm or less, and the thickness X 3Is preferably 0.0025 μm or more. By having a major axis, a minor axis, and a thickness in such a range, it is possible to effectively hide the Zn-based alloy plating layer while suppressing the colored pigment from protruding from the coating film. The average particle size of the coloring pigment according to the present invention is, for example, preferably 7 μm or more and 30 μm or less, and the average aspect ratio is preferably 20 or more. By having an average particle size in such a range, it is possible to effectively hide the Zn-based alloy plating layer while suppressing the coloring pigment from protruding from the surface of the coating film. Further, since the coloring pigment has a high aspect ratio, it is possible to make a wide range of the Zn-based alloy plating layer invisible by the coloring pigment, and it is possible to further enhance the blackening resistance. If the average particle size of the coloring pigment is less than 7 μm, the Zn-based alloy plating layer cannot be sufficiently made invisible, and blackening resistance may be insufficient. On the other hand, when the average particle size of the coloring pigment exceeds 30 μm, the possibility that the coloring pigment protrudes from the coating film increases, and there is a possibility that sufficient corrosion resistance cannot be guaranteed. Further, if the average aspect ratio is less than 20, the Zn-based alloy plating layer cannot be sufficiently made invisible, and the blackening resistance may be insufficient. The average particle size of the coloring pigment according to the present invention is more preferably 10 μm or more and 25 μm or less. Further, the average aspect ratio is more preferably 25 or more, and further preferably 30 or more. The upper limit of the average aspect ratio is not limited, but may be 100, for example. Further, in order to make the Zn-based alloy plating layer invisible more effectively by using the coloring pigment, the values ​​of the major axis X 1 and the minor axis X 2 are close to each other, that is, the ratio X 1 / X 2It is advantageous that is close to 1.0. In the present invention, for example, the ratio X 1 / X 2 is preferably 1.0 or more and 3.0 or less, more preferably 1.0 or more and 2.5 or less, and even more preferably 1.0 or more and 2.0 or less. There can be. [0038] 　Since the coloring pigment according to the present invention is contained in the coating film, the thickness X 3 of the coloring pigment is smaller than the average thickness T 1 of the coating film . Further, if the coloring pigment protrudes from the coating film, an invasion route of a corrosion factor may be formed and the corrosion resistance may be deteriorated. Therefore, the thickness X 3 of the coloring pigment is smaller than the average thickness T 1 of the coating film. Is more advantageous. For example, the thickness X 3 of the color pigment is preferably 0.5 T 1 or less, more preferably 0.4 T 1 or less. [0039] 　(Rust-preventive pigment) 　The rust-preventive pigment used in the coating film in the present invention may contain one or more of Si, Mo, W and Ba. Preferably, one or more of Si, Mo and Ba are included. Specific compounds thereof include, but are not limited to, silica (Grace, MSK-8D), calcium-modified silica (WRGrace, SHIELDEXC303), barium borate (Showa Kagaku Reagent). ), Barium metaborate (Reagent manufactured by Showa Kagaku Co., Ltd.), Zinc molybdate (Reagent manufactured by Wako Pure Chemical Industries, Ltd.), Calcium molybdate (Reagent manufactured by Wako Pure Chemical Industries, Ltd.), Sodium tungstate (Reagent manufactured by Kanto Chemical Co., Ltd.), Examples thereof include calcium tungstate (reagent manufactured by Kanto Chemical Co., Ltd.) and tungsten oxide (reagent manufactured by Kanto Chemical Co., Ltd.). Preferably, the rust preventive pigment is silica. In addition, the rust preventive pigment can be porous. By making it porous, the specific surface area is large and the apparent specific gravity is low, so that it becomes easier to thicken the coating film on the surface side. For example, as the rust preventive pigment, a rust preventive pigment (for example, silica) having a specific surface area of ​​20 m 2 / g or more, for example, 50 m 2 / g or more, 100 m 2 / g or more, or 200 m 2 / g or more can be used. it can. The upper limit of the specific surface area of ​​the rust preventive pigment is not particularly limited, but may be , for example, 500 m 2 / g. In the present specification, the "apparent specific gravity" is the density when the rust preventive pigment itself and the internal voids are taken as the volume, and includes the "volume of the rust preventive pigment itself" and the "volume of the internal voids". Is done. [0040] 　The average concentration of the rust preventive pigment in the coating film can be 3 to 12% by mass. Within such a range, the coating film sufficiently acts as a film for preventing corrosion of the Zn-based alloy plating layer, and high corrosion resistance can be provided. If the average concentration of the rust preventive pigment in the coating film is less than 3%, the concentration of the rust preventive pigment in the entire coating film is insufficient regardless of the distribution of the concentration of the rust preventive pigment in the coating film, resulting in sufficient corrosion resistance. You may not be able to get it. On the other hand, if the average concentration of the rust preventive pigment in the coating film exceeds 12%, the effect of improving the corrosion resistance by increasing the rust preventive pigment is reduced, which may be disadvantageous in terms of cost. Furthermore, the adhesion may be reduced. The average concentration of the rust preventive pigment in the coating film may be 4% or more, 5% or more or 6% or more, and may be 11% or less or 10% or less. The average concentration of the rust preventive pigment in the coating film is preferably 5 to 12% or less, more preferably 5 to 10% or less. [0041] 　Here, the "average concentration of the rust preventive pigment in the coating film" is obtained by using the same method as the above-mentioned "average concentration of the coloring pigment in the coating film". [0042] 　The rust preventive pigment in the coating film is concentrated on the surface side of the coating film. The indicators of the concentration of the rust preventive pigment are the average concentration C B1 of the rust preventive pigment existing in the region of width T 2 from the surface of the coating film in the thickness direction of the coating film, and the Zn-based alloy plating layer side of the coating film. It is determined by the ratio C B1 / C B2 to the average concentration C B2 of the rust preventive pigment existing in the region of width T 2 in the thickness direction of the coating film from the interface . As described above , it is determined by T 2 (μm) = 0.1 × T 1 (μm) + 1.1 μm. The ratio C B1 / C B2 of the surface-treated steel sheet according to the present invention is 1.2 or more and 5.0 or less when the ratio C A1 / C A2 for the above-mentioned colored pigment is 0.2 or more and 0.9 or less. Therefore, in order to more reliably obtain the effect of thickening the rust preventive pigment on the surface layer side, it is preferably 1.3 or more and 4.0 or less. If this ratio C B1 / C B2 is less than 1.3, the effect of thickening the rust preventive pigment, which is to improve the corrosion resistance of the flat surface portion for a long period of time, may not be sufficiently obtained. On the other hand, ratio C B1When / C B2 exceeds 4.0, the rust preventive pigment becomes too thick on the surface side of the coating film, and when the coating film is thinned over time, the surface where the rust preventive pigment is insufficient in a relatively short time. May be exposed and sufficient long-term corrosion resistance may not be obtained. The ratio C B1 / C B2 may be 1.5 or more, 1.8 or more or 2.0 or more, and may be 3.8 or less, 3.5 or less or 3.2 or less. The ratio C B1 / C B2 is preferably 1.5 or more and 3.5 or less, and more preferably the ratio C B1 / C B2 is 1.8 or more and 3.2 or less. [0043] 　C B1 and C B2 are obtained by the same method as C A1 and C A2 described above . [0044] 　The rust preventive pigment in the coating film is distributed in the coating film so that the above ratio C B1 / C B2 value is 1.3 or more and 4.0 or less, that is, the rust preventive pigment is on the surface side of the coating film. By thickening, the corrosion resistance of the surface of the coating film is sufficiently improved, and the long-term corrosion resistance of the flat surface portion is further improved. [0045] 　The average particle size of the rust preventive pigment can be appropriately selected according to the average thickness T 1 of the coating film and the like, but can be 0.2 to 10 μm. The average particle size of the rust preventive pigment is preferably 0.4 to 8 μm, more preferably 0.5 to 6 μm. [0046] 　The average particle size of the rust preventive pigment can be determined by the same method as the average particle size of the coloring pigment described above. That is, for 10 or more rust preventive pigments, element mapping by FE-EPMA is performed from the surface and cross-sectional direction of the coating film to obtain the major axis Y 1 , minor axis Y 2 and thickness Y 3 of the rust preventive pigments . The average particle size of the rust preventive pigment can be obtained from the value. [0047] 　Further, from the viewpoint of adhesion, the thickness Y 3 of the rust preventive pigment is preferably smaller than the average thickness T 1 of the coating film to some extent like the coloring pigment . For example, the thickness Y 3 of the rust preventive pigment is , preferably 0.5 T 1 or less, more preferably 0.4 T 1 or less, even more preferably 0.3 T 1 or less, most preferably 0.1 T 1 or less. [0048] 　(Binder resin) 　The binder resin used as a component of the coating film in the present invention is preferably a polyester resin, a urethane resin, or an acrylic resin. In the present invention, it is important to use an imino-based melamine resin as a curing agent for these resins. Preferably, the binder resin in the present invention is a polyester resin. The polyester resin used in the present invention preferably has a glass transition temperature Tg of −20 to 70 ° C. and a number average molecular weight of 3000 to 30000. When the binder resin is a urethane resin, the Tg is preferably 0 to 50 ° C., and the number average molecular weight is preferably 5000 to 25000. When the binder resin is an acrylic resin, the Tg is preferably 0 to 50 ° C., and the number average molecular weight is preferably 3000 to 25000. Further, in the present invention, an aqueous solvent is used as the solvent for the binder resin. [0049] 　In the coating film in the present invention, if necessary, waxes such as polyethylene wax or PTFE wax, resin beads such as acrylic resin beads or urethane resin beads, and phthalocyanine blue, phthalocyanine green, methyl orange, methyl violet, etc. Alternatively, a dye or the like such as alizarin can be added. It is more preferable to add these because the strength of the coating film can be increased and a desired color can be imparted to the coating film. The amount of these additions may be appropriately determined so as not to be disadvantageous to the coating film in the present invention. [0050] 　In particular, dyes can be used as colorants to impart the desired color to the coating film in the present invention, and thus the surface-treated steel sheet according to the present invention. The dyes may be used alone or in combination of a plurality of dyes. The type of dye that can be used in the coating film in the present invention is not particularly limited, but known dyes can be used, and for example, phthalocyanine blue, phthalocyanine green, methyl orange, methyl violet, or alizarin are used. be able to. [0051] 　[Method for manufacturing surface-treated steel sheet] 　An example of the method for manufacturing a surface-treated steel sheet according to the present invention will be described below. The surface-treated steel sheet according to the present invention is, for example, an aqueous solution in which a coloring pigment and an anticorrosive pigment are added on a Zn-based alloy plating layer formed on the steel sheet, and an imino-based melamine resin is added as a curing agent for the binder resin. It can be produced by applying a paint and heating it according to a predetermined heat pattern to cure the paint. [0052] 　 As the 　steel sheet, a steel sheet having an arbitrary thickness and chemical composition can be used. For example, a cold-rolled steel sheet having a plate thickness of 0.25 to 3.5 mm can be used. The Zn-based alloy plating layer can be formed, for example, by hot-dip galvanizing Zn—Al—Mg alloy plating on a steel sheet to a thickness of 1 to 30 μm. Hot-dip galvanizing can be performed, for example, in a hot-dip galvanizing bath at 400 to 550 ° C. to which various metals are added. The Al and Mg contents are mass%, Al: 0.01 to 60%, Mg: 0.001 to 10%, and the balance is typically Zn and impurities. Further, in addition to the chemical composition as described above, it is also possible to form a Zn—Al—Mg—Si alloy plating layer containing Si: 0.001 to 2% in mass%. [0053] 　 The paint is a binder resin such as a polyester resin (for example, molecular weight: 16000, Tg: 10 ° C.) dispersed in a solvent and an imino-based melamine resin in a solid content mass ratio of 100: 10 to 100 :. It can be obtained by mixing at 30 and then dispersing a predetermined amount of the coloring pigment and the rust preventive pigment in the mixture. Moreover, as a solvent, an aqueous solvent (for example, water) is used. [0054] 　In the surface-treated steel sheet according to the present invention, as described above, the rust preventive pigment in the coating film is concentrated on the surface side of the coating film, and the coloring pigment in the coating film is concentrated on the Zn-based alloy plating layer side. The formation of such concentration distributions of rust preventive pigments and color pigments is possible by utilizing the phenomenon that the imino-based melamine resin is thickened on the surface layer of the coating film when it is cured under specific conditions. The present inventors have found. That is, the concentration of the rust preventive pigment on the surface side is achieved by selecting a rust preventive pigment (for example, porous silica) having a smaller apparent specific gravity than the colored pigment, that is, a large specific surface area. This is possible when the rust preventive pigment moves to the surface layer together with the melamine resin when the base melamine resin is concentrated on the surface layer of the coating film. Regarding the mechanism of this thickening, not only the effect of the apparent difference in specific gravity between the coloring pigment and the anticorrosive pigment, but also the chemical affinity between the imino-based melamine resin and the anticorrosive pigment, which are mutually mutual. It is also considered that the action causes the imino-based melamine resin to thicken on the surface layer and the rust preventive pigment to thicken on the surface side of the coating film. [0055] 　Further, when a water-based paint is used as a paint for forming a coating film as in the present invention, the concentration of the imino-based melamine resin on the surface layer is more remarkable than when a solvent-based paint is used. The present inventors have found. It is considered that this is because there are more imino-based melamine resins that did not crosslink with polyester or the like when the paint was cured to form a coating film, in the water-based paint as compared with the solvent-based paint. In other words, in the case of water-based paints, polyester resin and the like are dispersed in an emulsion state, so that the cross-linking reaction between the reactive functional groups (OH groups) inside the emulsion particles and the imino-based melamine resin occurs. This is thought to be due to the increase in excess imino-based melamine resin that is inhibited. As a result, it is considered that the self-condensation reaction of the imino-based melamine was more likely to occur than the cross-linking reaction, and the concentration of the imino-based melamine resin on the surface layer was remarkable. Furthermore, in water-based paints, the effect of thickening the imino-based melamine resin is large because the compatibility between water and melamine is low and the surface free energy of the imino-based melamine resin is smaller than that of water. It can also be considered that this is because the melamine resin easily floats on the surface layer. Therefore, in the present invention, it is effective to use an aqueous solvent as the solvent in order to promote the concentration of the imino-based melamine resin on the surface layer. [0056] 　As the melamine resin, in addition to the imino-based melamine resin used in the present invention, a methylated melamine resin and a butylated melamine resin are generally known. However, when a methylated melamine resin is added as a curing agent to the water-based paint, the phenomenon of thickening the rust-preventive pigment on the surface layer during baking does not occur remarkably, and the water-based paint is butylated as a curing agent. The present inventors have found that when a melamine resin is used, the paint solidifies when mixed with an aqueous solvent and cannot be used as a paint. Therefore, in order to obtain a coating film as in the present invention, it is extremely effective to use a combination of an aqueous solvent, a binder resin, and an imino-based melamine resin as a curing agent for the binder resin. [0057] 　Due to the properties of the imino-based melamine resin in such a water-based paint, when the rust preventive pigment is concentrated on the surface side of the paint film, a relatively heavy coloring pigment such as aluminum in the paint film is applied to the paint film. It becomes difficult to distribute on the surface side of, and it is relatively concentrated on the Zn-based alloy plating layer side. In other words, the rust preventive pigment is concentrated on the surface side of the coating film, so that the coloring pigment is suppressed so as to stay on the Zn-based alloy plating layer side in the coating film. In this way , a surface-treated steel sheet having a rust preventive pigment ratio C B1 / C B2 in the coating film of 1.2 or more and 5.0 or less, preferably 1.3 or more and 4.0 or less can be obtained. A surface-treated steel sheet according to the present invention having a color pigment ratio C A1 / C A2 in a coating film of 0.2 or more and 0.9 or less can be obtained. Further, in order to concentrate the rust preventive pigment and the color pigment on the surface layer side and the Zn-based alloy plating layer side, respectively, depending on the properties of the imino-based melamine resin in the water-based paint, the particle size and specific gravity of the rust preventive pigment should be selected. Is valid. In order to obtain the concentration distribution of the rust preventive pigment and the color pigment according to the present invention, it is effective to set the average particle size of the rust preventive pigment to 0.2 to 10 μm and the specific surface area to 20 m 2 / g or more. [0058] 　When it can be used in combination with a coloring pigment and a rust preventive pigment, an acidic catalyst can be added to the coating film in order to thicken the melamine resin on the surface layer of the coating film, if necessary. The acidic catalyst is not limited, but is a weakly acidic catalyst (Catalyst 296-9 / manufactured by Ornex Japan), a strongly acidic catalyst (Catalyst 600 / manufactured by Ornex Japan), or an amine block strongly acidic catalyst (Catalyst). 602 / manufactured by Ornex Japan Co., Ltd.) can be used. The acidic catalyst is added, for example, in an amount of 0.1 to 1.0% by mass in the coating material. [0059] 　 　Next, the obtained coating film can be applied onto the Zn-based alloy plating layer to a predetermined thickness, for example, with a roll coater or the like, and baked and cured in a predetermined heat pattern. The baking is carried out at a heating rate of 5 to 70 ° C./sec so that the steel sheet temperature is finally 180 to 230 ° C. Specifically, in the process of heating to the steel sheet temperature, the steel sheet temperature can be maintained at a temperature between 70 and 150 ° C., preferably between 100 and 150 ° C. for 1 to 5 seconds, preferably 1 to 3 seconds. is important. That is, after applying the paint on the Zn-based alloy plating layer, the plated steel plate at room temperature (for example, 20 ° C.) is once heated to 70 to 150 ° C. (first heating step) and held at that temperature for 1 to 5 seconds. The coating film according to the present invention can be obtained by (temperature holding step) and further heating to 180 to 230 ° C. (second heating step). Such a heat pattern can be realized in two heating furnaces. Specifically, the heating furnace A and the heating furnace B are installed in order in the passing direction of the Zn-based alloy-plated steel sheet coated with the paint, and the heat treatment is performed between the heating furnace A and the heating furnace B. It is advisable to provide a temperature holding region in which this is not performed. Therefore, the plated steel sheet coated with the paint in the heating furnace A is heated to a temperature between 70 and 150 ° C., held at that temperature in the temperature holding region for 1 to 5 seconds, and then in the heating furnace B at 180 to 230 ° C. The temperature can be raised to between and the paint can be cured. The heat pattern may be performed continuously or in a batch manner as described above. [0060] 　By carrying out the temperature holding step at the holding temperature and holding time as described above, the rust preventive pigment can be efficiently concentrated on the surface layer as the surface layer of the imino-based melamine resin is thickened. If the holding time as described above is not provided and / or if the temperature in the first heating step is too high, the rust preventive pigment according to the present invention can be concentrated, and therefore the colored pigment can be efficiently concentrated. It may not be possible. In particular, when the holding temperature exceeds 150 ° C., the binder resin reacts with the curing agent, the viscosity of the paint increases, and the rust preventive material becomes difficult to move to the surface layer. Therefore, the desired rust preventive pigment can be thickened on the surface layer. It may not be obtained. [0061] 　The concentration ratio of the rust preventive pigment (concentration ratio of the coloring pigment) according to the present invention is based on the melamine concentration as described above, and can be controlled by the melamine resin type and the melamine resin concentration used. In addition, it can be adjusted by the heat pattern at the time of curing the coating film and the average particle size / specific gravity of the rust preventive pigment. Specifically, an aqueous solvent, a binder resin such as a polyester resin, and a curing agent which is an imino-based melamine resin are used so that the ratio of the binder resin: the curing agent is in the range of 100:10 to 100:30. To prepare a paint by adding a coloring pigment and an anticorrosive pigment. Then, as described above, after applying such a paint on the Zn-based alloy plating layer, it is once heated to 70 to 150 ° C., held at the heated temperature for 1 to 5 seconds, and then further heated to 180 to 230 ° C. Heat to the steel plate temperature. By doing so, it is possible to effectively concentrate the rust preventive pigment on the surface layer side and, accordingly, the coloring pigment on the Zn-based alloy plating layer side. It is effective that the average particle size of the rust preventive pigment added to the paint is 0.2 to 10 μm and the specific surface area is 20 m 2 / g or more. [0062] 　By using the manufacturing method as described above, the surface-treated steel sheet according to the present invention can be manufactured. That is, in the thickness direction of the coating film from the interface between the average concentration C A1 of the coloring pigment existing in the region of the width T 2 from the surface of the coating film in the thickness direction of the coating film and the Zn-based alloy plating layer side of the coating film. The ratio C A1 / C A2 to the average concentration C A2 of the color pigment existing in the region of the width T 2 is 0.2 or more and 0.9 or less, and T 2 (μm) = 0.1 × T 1 (μm). A surface-treated steel sheet having a size of +1.1 μm can be manufactured. Example [0063] 　The surface-treated steel sheet according to the present invention will be described in more detail below with some examples. However, it is not intended that the particular examples described below limit the scope of the invention described in the claims. [0064] 　 　(Formation of Zn-based alloy plating layer) 　A cold-rolled steel sheet with a thickness of 1 mm has a chemical composition of Al: about 11%, Mg: about 3%, and Zn: about 86%. It was immersed in a hot-dip plating bath at 450 ° C. for 3 to 5 seconds to form a Zn-11% Al-3% Mg alloy plating layer having a thickness of about 10 μm on a cold-rolled steel sheet. Further, the composition of the hot-dip plating bath was changed, and the Zn-1% Al-1% Mg alloy plating layer and the Zn-40% Al-8% Mg alloy plating having a thickness of about 10 μm were plated on the cold-rolled steel sheet by the same procedure. A layer was formed. Alternatively, a 1 mm thick cold-rolled steel sheet is placed in a hot-dip galvanizing bath having a chemical composition of Al: about 11%, Mg: about 3%, Si: about 1%, and Zn: about 85% at about 450 ° C. 3 to 5 After immersion for seconds, a Zn-11% Al-3% Mg-1% Si alloy plating layer having a thickness of about 10 μm was formed on the cold-rolled steel sheet. Further, the composition of the hot-dip plating bath was changed, and the Zn-11% Al-3% Mg-0.4% Si alloy plating layer and Zn-11% Al having a thickness of about 10 μm were placed on the cold-rolled steel sheet by the same procedure. A -3% Mg-1.5% Si alloy plating layer was formed. [0065] 　(Preparation of paint) A 　polyester resin (molecular weight: 16,000; glass transition point: 10 ° C.) was dispersed as an emulsion in water as a binder resin, and the pH was adjusted to 8.0 to 9.0. An imino-based melamine resin was mixed therein. The concentration ratio of the polyester resin to the imino-based melamine resin was 100:20. Next, in the mixture , resin-coated aluminum having an average particle size of 10 μm and an average aspect area of ​​25 (major axis X 1 : 12 μm, minor axis X 2 : 8 μm, thickness X 3 : 0.40 μm) and protection the average particle diameter 3μm of Si two compounds as rust pigment (silica a: a specific surface area of 320 m 2 / g, silica B: specific surface area of 180 m 2 / g), Ba two compounds (barium borate a: a specific surface area of 40 m 2 / g , Barium borate B: specific surface area 4.2 m 2 / g), Mo compound (calcium molybdate: specific surface area 80 m 2 / g) or W compound (tungsten oxide: specific surface area 40 m 2)A paint was prepared by adding any of / g). The amount of the coloring pigment and the rust preventive pigment added was appropriately adjusted so that a desired concentration could be obtained in the coating film when measured using GD-OES, as described later. The types of rust preventive pigments added are shown in Table 1 (Si-A is silica A, Si-B is silica B, Ba-A is barium borate A, Ba-B is barium borate B, and Mo is molybdic acid. Calcium and W indicate tungsten oxide). In addition, sample No. Reference numeral 32 denotes an example in which the rust preventive pigment was not added, and the sample No. 32 was used. No. 35 is an example in which a methylated melamine resin is used instead of the imino-based melamine resin. Although not shown in Table 1, a paint using a butylated melamine resin instead of the imino-based melamine resin was also prepared, but a coating film could not be formed because the paint solidified during preparation. In Table 1, the one using the imino-based melamine resin is shown as "imino-based", and the one using the methylated melamine resin is shown as "methylation". [0066] 　(Formation of coating film) 　The coating film prepared as described above is applied on a Zn-based alloy plating layer with a roll coater so that the average thickness T 1 of the formed coating film is 5 μm, and cured by baking. I let you. The baking was performed under the conditions as shown in Table 1 (reached temperature A, heating time A, heating rate A, holding time, reaching temperature B, heating time B, heating rate B). Specifically, first, the temperature at the start of baking of the plated steel sheet on which the above Zn-based alloy plating layer is formed is maintained at 20 ° C., and after applying the above paint to the plated steel sheet, as shown in Table 1. In the heating furnace A, the temperature was raised to the ultimate temperature A at the heating rate A, and after holding the temperature at the ultimate temperature A for a predetermined holding time, the temperature was raised to the ultimate temperature B in the heating furnace B at the heating rate B. The ratio C A1 / C A2 and / or the ratio C B1 / C B2 of the sample of the surface-treated steel sheet was adjusted by changing the combination of the heating rate at the time of baking, the temperature reached by the steel sheet, and the holding time . [0067] 　From the obtained coating film, the average concentration of the coloring pigment in the coating film; the average concentration of the anticorrosive pigment in the coating film; the ratio C A1 / CA2 for the coloring pigment ; and the ratio C B1 / C for the anticorrosive pigment. B2 was determined by elemental analysis using GD-OES. The values ​​determined in this way are shown in Table 1. [0068] 　 Prepare a sample of surface-treated steel sheet as 　described above, and prepare the plating chemical composition, concentration and concentration distribution of coloring pigment and rust-preventive pigment as shown in Table 1, and type of rust-preventive pigment. The evaluation test of corrosion resistance and blackening resistance was carried out for each sample having. [0069] 　(Evaluation test of corrosion resistance) 　Each sample was subjected to a salt spray test (based on JASO M609-91 method) as an evaluation test of corrosion resistance. This salt spray test involves (1) salt spray for 2 hours (5% NaCl, 35 ° C); (2) drying for 4 hours (60 ° C); and (3) wetting for 2 hours (50 ° C, humidity of 95% or more). A total of 120 cycles (total of 960 hours) were carried out as one cycle. In order to prevent corrosion from the end face, the end face of each sample was sealed with tape and tested. Each sample had a width of 50 mm and a length of 100 mm. [0070] 　The evaluation of corrosion resistance was performed by observing the surface (planar portion) of the sample after 960 hours of the salt spray test with an optical microscope and determining the rust generation area ratio Z. Specifically, first, the surface of the sample was read by a scanner. After that, the area where rust was generated was selected using image editing software, and the rust area ratio was calculated. This procedure was performed on five samples, and the "rust-generated area ratio Z" was determined by averaging the rust-generated area ratio. Based on the "rust generation area ratio Z" determined for each sample in this way, the score of each sample was determined in eight stages as follows. A score of 3 or higher was used as a passing score for corrosion resistance. 　Score 8: Z = 0% 　Score 7: 0%