JPWO2020213690A1 - Galvanized steel sheet - Google Patents

Abstract

A zinc-based material located on at least one surface of a steel sheet (11, 11') and the steel sheet (11, 11') and having a hairline formed as a recess (101, 101') extending in a predetermined direction. Oxide layers (14, 14') located on the surfaces of the plating layer (13, 13') and the zinc-based plating layer (13, 13') and having an average thickness of 0.05 μm or more and 3.0 μm or less. ), And a zinc-based plated steel sheet (1, 1').

Description

The present invention relates to a galvanized steel sheet. The present application claims priority under Japanese Patent Application No. 2019-078556 filed in Japan on April 17, 2019 and Japanese Patent Application No. 2019-18265 filed in Japan on October 3, 2019. These contents are incorporated here.

Generally, design is required for articles that people can see, such as electrical equipment, building materials, and automobiles. As a method of enhancing the design, a method of painting or attaching a film to the surface of an article is common, but in recent years, mainly in nature-oriented Europe and the United States, materials that make use of the texture of metal have been used. The application is increasing. From the viewpoint of utilizing the texture of metal, painting and resin coating impair the texture of metal, so stainless steel and aluminum, which have excellent corrosion resistance even when unpainted, are used as the material of the article. Further, in order to improve the design of the stainless steel material or the aluminum material, fine arcuate irregularities called vibrations are added, or embossing is performed.
In particular, the appearance with fine linear irregularities called hairlines is preferred and is often used. Furthermore, in order to enhance the design of stainless steel and aluminum, they may be colored.
As the coloring method, a method of coating the surface of the stainless steel material or the aluminum material with a colored coating film, a method of changing the thickness of the oxide layer existing on the surface of the stainless steel material or the aluminum material, and the like are used. Especially when a high degree of blackness is required, it is not preferable to color with only the coating film because the hairline is hidden and invisible. When high blackness is required, a method of blackening with an oxide layer is used.

Hairline finish (HL finish) is defined in JIS G4305: 2012 as one of the surface finishes of stainless steel materials, "polished with an abrasive of an appropriate particle size so as to have a continuous polish". ing.

However, since stainless steel and aluminum are expensive, inexpensive materials that replace these stainless steel and aluminum are desired. As one of such alternative materials, a metal texture having a hairline appearance, which has the same high design and appropriate corrosion resistance as stainless steel and aluminum materials and is suitable for use in electrical equipment and building materials. There is a steel material with excellent (metallic feeling).

As a technique for imparting appropriate corrosion resistance to a steel material, a technique for imparting zinc plating or zinc alloy plating having excellent sacrificial corrosion resistance to the steel material is widely used.
As a technique for steel materials in which a hairline design is added to such zinc plating or zinc alloy plating (hereinafter, zinc plating and zinc alloy plating are collectively referred to as "zinc-based plating"), a hairline orthogonal to the hairline direction is used. A translucent adhesive layer and a translucent film layer plating layer are provided on the surface of a plating layer having a surface roughness Ra (arithmetic average roughness) of 0.1 to 1.0 μm in the orthogonal direction. Technique for forming (see Patent Document 1 below),
The roughness parameters (Ra and PPI) in the hairline direction and the hairline orthogonal direction formed on the surface layer of the Zn-Al-Mg-based hot-dip plating layer are set to a specific range, and on the surface of the Zn-Al-Mg-based hot-dip plating layer. Technique for forming a transparent resin film layer (see Patent Document 2 below),
A technique for coating a steel sheet whose texture has been transferred to Zn and Zn-based alloy plating by rolling with a resin so that the surface roughness is within a certain range (see Patent Document 3 below).
Has been proposed.
Patent Document 6 discloses a technique for forming a hairline on the surface of an oxide layer.

Further, as a technique for producing a black zinc-based plated steel sheet, a technique for oxidizing the surface of a zinc-based plated layer (see Patent Document 4 below) has been proposed.

Japan Registered Utility Model No. 3192959 Japanese Patent Application Laid-Open No. 2006-124824 Japan Special Table 2013-536901 Japanese Patent Application Laid-Open No. 63-65086 International Publication No. 2015/125887 Japanese Patent Application Laid-Open No. 2017-218647

However, in the technique of coating a steel plate with a hairline design with a black organic resin as proposed in Patent Documents 1 to 3, the hairline design is concealed by a black coating film, so that the hairline design is used. It was difficult to achieve both a black appearance.

Further, in the method of forming an oxide film on the surface of the zinc-based plating layer as proposed in Patent Document 4, the particle size of the oxide precipitated on the surface of the zinc-based plating layer becomes large, so that the appearance is black. The challenge was to achieve both a metallic feel and a metallic luster.

Here, as a method for forming a hairline, a steel sheet rolling method in which a plated steel sheet for which a hairline is to be formed is rolled by a rolling roll or the like having a predetermined roughness, and a plating grinding method for grinding the surface of a plated steel sheet for which a hairline is to be formed are used. , There is. The lack of metallic feeling (metal glossiness) as described above is particularly caused by forming a hairline on the original plating plate in the above-mentioned steel sheet rolling method, then electroplating, and then depositing an oxide layer on the surface of the plating layer. This was remarkable in the plated steel sheet on which the hairline was formed.
The reason why the lack of metallic feeling is remarkable is not clear, but in the plated steel sheet produced by applying the hairline to the plating original plate by the steel sheet rolling method, the unevenness of the plating crystal particles exists on the outermost surface of the plating layer. It is considered that this is because the incident light is diffusely reflected on the surface of the oxide layer by forming coarse particles on the surface of the plating layer by oxidizing the unevenness.

Further, when a hairline is formed on a steel sheet after plating by a steel sheet rolling method as described in Patent Document 2, the unevenness of the crystal particles of the plating is crushed by rolling. Therefore, there is no problem that the metallic feeling is insufficient due to diffused reflection of light, but since the plating surface is smoothed, the particle size of the oxide formed thereafter becomes small, and the adhesion with the resin coating coated on the surface becomes small. The problem arises that there is a shortage of.

As a method for improving the glossiness, a method of adding a predetermined organic substance additive to an electroplating solution to make the plating crystal grains finer is known (see, for example, Patent Document 5 above). As a result, the particle size of the oxide formed on the surface of the plating layer is also reduced, and the glossiness is improved. However, when the crystal particles of the plating are miniaturized, the particle size of the oxide layer is also reduced, so that there is a problem that the processing adhesion with the resin film is lowered when the resin is coated. Further, in the method described in Patent Document 5, it is necessary to use an organic substance additive in order to obtain smooth plating, and there is a problem that the drag-out (waste liquid) treatment cost of the plating solution increases.

Since the stainless steel material itself has good corrosion resistance due to the oxide film existing on the surface of the stainless steel material, coating for improving the corrosion resistance is unnecessary. That is, since the metal base itself can be used for the surface, basically no resin coating is required. On the other hand, when a resin coating is applied to a stainless steel material, the purpose is to impart coloring or another texture. Therefore, in stainless steel materials, the loss of metallic feeling as found by the present inventors did not pose a problem. The same applies to aluminum materials.

Patent Document 6 discloses a technique for forming a hairline on the surface of an oxide layer. However, when the present inventor examined the technique disclosed in Patent Document 6, it was found that there was a problem different from the metallic feeling. Specifically, in Patent Document 5, an oxide layer is formed by steam-oxidizing a zinc-based plating layer. Such steam oxidation needs to be carried out over time in a complicated and large-scale facility. Therefore, it cannot be performed in-line (that is, on the same line as other processes such as plating). Therefore, the formation of the oxide layer is costly. The hairline obtained by partially grinding the formed oxide layer discolors with time in the atmosphere. That is, it is necessary to control and shorten the time required for grinding to coat the upper layer with the film. Further, since the oxide layer formed by steam oxidation is thick, it is necessary to form the hairline deeply in order to form the hairline to a visible level. That is, in order for the hairline to be visible, it is necessary to form the hairline at least to a depth up to the zinc-based plating layer below the oxide layer. In Patent Document 6, since the oxide layer is thick, it is necessary to form a hairline deeper by that amount. For this reason, not only is it time-consuming to form the hairline, but also a large amount of waste such as shavings is generated. Therefore, Patent Document 6 cannot fundamentally solve the problem of metallic feeling.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to have good corrosion resistance, good blackness and hairline even when an inexpensive steel material is used. An object of the present invention is to provide a galvanized steel sheet having an appearance and excellent metallic feeling and processing adhesion.

Means for solving the problem include the following aspects.
<1> The zinc-based plated steel sheet according to the embodiment of the present invention is a zinc-based plated steel sheet located on the surface of at least one of the steel sheet and the steel sheet, and has a hairline formed as a recess extending in a predetermined direction. It includes a layer and an oxide layer located on the surface of the zinc-based plating layer and having an average thickness of 0.05 μm or more and 3.0 μm or less.
<2> In the zinc-based plated steel sheet according to <1>, the oxide layer may be located at least on the surface of the zinc-based plated layer other than the recess.
<3> The zinc-based plated steel sheet according to <1> or <2> may further include a translucent organic resin coating layer on the surface of the oxide layer.
<4> In the zinc-based plated steel sheet according to any one of <1> to <3>, the blackness of the surface of the zinc-based plated steel sheet may be 40 or less in ^{L * value.}
<5> In the zinc-based plated steel sheet according to any one of <1> to <4>, the oxide layer comprises a rough portion and a smooth portion, and the rough portion has a surface roughness Ra _A. The smooth portion includes a region having a surface roughness Ra _B of more than 5 nm and 500 nm or less, and the boundary between the rough portion and the smooth portion is orthogonal to the predetermined direction. 1 of the maximum height Ry obtained by subtracting the lowest point H _{0 from the highest point H 1} of the oxide layer within an observation width of 1 cm along the hair line orthogonal direction in the cross section in the direction orthogonal to the hairline and in the plate thickness direction. Assuming that the height is 3/4 and it is on a virtual straight line parallel to the hairline orthogonal direction, the oxide layer in which the boundary between the rough portion and the smooth portion is defined is viewed in a plan view and has the same area as each other. a unit, an area of the coarse portion and _{S a,} the area of the smooth portion is taken as _{S B,} the area ratio _S B / _{S a} is from 0.6 to 10.0, and the rough portion The average height difference between the rough portion and the smooth portion adjacent to the rough portion may be 0.3 μm or more and 5.0 μm or less.
Galvanized steel sheet according to <6> above <5> is the total area of the region the surface roughness Ra _A of the rough portion is less than 500nm ultra 5000nm is, relative to the area _{S A} of the rough portion 85 % or more, and the total area of regions the surface roughness Ra _B in the smooth portion is less than 5nm super 500nm is good I is 65% or more with respect to the area _{S B} of the smoothing section.
<7> In the galvanized steel sheet according to <5> or <6>, the rough portion is formed in the hairline, and the average length along the stretching direction of the hairline may be 1 cm or more.
<8> In the galvanized steel sheet according to <5> or <6>, the smooth portion is formed in the hairline, and the average length along the stretching direction of the hairline may be 1 cm or more.
<9> In the zinc-based plated steel sheet according to any one of <1> to <8>, the hairline has an average of three hairlines in an arbitrary 1 cm width range along the direction orthogonal to the hairline. It may be present at a frequency of cm or more and 80 lines / cm or less.
<10> In the zinc-based plated steel sheet according to any one of <1> to <9>, a recess is formed on the surface of the steel sheet at a position corresponding to the hairline in the zinc-based plated layer. good.
<11> In the zinc-based plated steel sheet according to any one of <1> to <10>, the zinc-based plating layer is a zinc-based electroplating layer, and the average adhesion amount of the zinc-based electroplating layer is May be 5 g / m ² or more and 40 g / m ² or less.
<12> In the zinc-based plated steel sheet according to <11>, the zinc-based electroplating layer contains a total of 5 masses of any one or more additive elements selected from the group consisting of Fe, Ni, and Co. It may contain% or more and 20% by mass or less, and a balance composed of Zn and impurities.
<13> In the zinc-based plated steel sheet according to any one of <1> to <10>, the zinc-based plating layer is a zinc-based hot-dip plating layer, and the average adhesion amount of the zinc-based hot-dip plating layer is May be more than 40 g / m ^{2 and} 150 g / m ² or less.
<14> In the zinc-based plated steel sheet according to <13>, the zinc-based hot-dip plating layer contains a total of 1% by mass or more of any one or more additive elements selected from the group consisting of Al and Mg. It may contain 60% by mass or less and a balance composed of Zn and impurities.
<15> In the zinc-based plated steel sheet according to <3> above, the organic resin coating layer may have a coloring pigment.
<16> In the galvanized steel sheet according to <1> or <2>, the concave portion and the flat portion which is a region other than the concave portion are formed on the surface of the oxide layer, and the concave portion is formed. The average depth is 0.1 μm or more and less than 3.0 μm, and the bottom of the recess reaches the zinc-based plating layer below the oxide layer, and the oxide layer existing in the recess is viewed in a plan view. The ratio AR1 / AR2 of the area ratio AR1 to the area ratio AR2 of the oxide layer existing in the flat portion in a plan view may be 0 or more and 0.5 or less.
<17> The zinc-based plated steel sheet according to <17> may have an average depth of the recesses of 0.1 μm or more and less than 2.0 μm.
<18> In the zinc-based plated steel sheet according to <17>, the zinc-based plating layer may be a zinc-based electroplating layer.
<19> In the zinc-based plated steel sheet according to any one of <16> to <18>, the oxide layer is selected from the group consisting of zinc hydroxide and zinc oxide. The above may be included.
<20> The zinc-based plated steel sheet according to any one of <16> to <18> may have an average thickness of the oxide layer of 0.05 μm or more and less than 3.0 μm.
<21> In the galvanized steel sheet according to any one of <16> to <20>, the recess includes a region where the surface roughness RaA'is more than 5 nm and 500 nm or less, and the flat portion has a surface roughness. It may include a region where RaB'is more than 500 nm and less than 5000 nm.
<22> The zinc-based plated steel sheet according to any one of <16> to <21> may have an average length of 1 cm or more along the length direction of the recess.
<23> In the zinc-based plated steel sheet according to any one of <16> to <22>, the recess is set in an arbitrary 1 cm width range along a direction orthogonal to the length direction of the recess. On average, it may be present at a frequency of 3 lines / cm or more and 80 lines / cm or less.
<24> In the zinc-based plated steel sheet according to any one of <16> to <23>, the average adhesion amount of the zinc-based plated layer ^{may be 5 g / m 2} or more and 40 g / m ² or less. ..
<25> The zinc-based plated steel sheet according to any one of <16> to <24> is selected from the group in which the oxide layer is composed of Fe, Ni, and Co as the second component. It may contain more than a species of additive element.
<26> In the zinc-based plated steel sheet according to any one of <16> to <25>, the zinc-based plating layer is one or more selected from the group consisting of Fe, Ni, and Co. The total of these additive elements may be 5% by mass or more and 20% by mass or less, and the balance of the zinc-based plating layer may be Zn and impurities.
<27> In the zinc-based plated steel sheet according to <3> above, the organic resin coating layer may contain a black pigment.
<28> The zinc-based plated steel sheet according to <27> has two or more organic resin coating layers, and the black pigment may be contained in any one or more layers other than the bottom layer.
<29> In the zinc-based plated steel sheet according to <28>, the organic resin coating layer may further contain any one or more additive elements selected from Si, P, and Zr.

As described above, according to the present invention, even when an inexpensive steel material is used, it has good corrosion resistance, good blackness and hairline appearance, and excellent metallic feeling and processing adhesion. Further, it becomes possible to provide a galvanized steel sheet.

It is explanatory drawing which showed typically an example of the structure of the galvanized steel sheet which concerns on one Embodiment of this invention, and is the cross-sectional view along the plate thickness direction. It is explanatory drawing which showed typically an example of the structure of the galvanized steel sheet which concerns on one Embodiment of this invention, and is the cross-sectional view along the plate thickness direction. It is explanatory drawing for demonstrating an example of the zinc-based plating layer which concerns on one Embodiment of this invention, and is the enlarged sectional view of the main part along the plate thickness direction. It is a graph for demonstrating an example of the zinc-based electroplating layer which concerns on one Embodiment of this invention. It is a graph for demonstrating an example of the zinc-based electroplating layer which concerns on one Embodiment of this invention. It is a graph for demonstrating an example of the zinc-based electroplating layer which concerns on one Embodiment of this invention. It is explanatory drawing for demonstrating another example of the structure of the galvanized steel sheet which concerns on one Embodiment of this invention, and is the enlarged sectional view of the main part along the plate thickness direction. It is explanatory drawing which schematically showed another example of the structure of the galvanized steel sheet which concerns on one Embodiment of this invention, and is sectional drawing along the plate thickness direction. It is explanatory drawing which schematically showed another example of the structure of the galvanized steel sheet which concerns on one Embodiment of this invention, and is sectional drawing along the plate thickness direction. It is a schematic diagram which shows an example of the surface of the zinc-based electroplating layer on which the oxide layer was formed which the zinc-based electroplating steel sheet which concerns on one Embodiment of this invention has. It is sectional drawing for demonstrating the virtual line which forms the boundary between a rough part and a smooth part, and shows the case of the form shown in FIG. It is sectional drawing for demonstrating the virtual line which forms the boundary between a rough part and a smooth part, and shows the case of the form shown in FIG. It is explanatory drawing which showed typically an example of the structure of the galvanized steel sheet which concerns on the modification of this invention, and is the cross-sectional view along the plate thickness direction. It is explanatory drawing which showed typically an example of the structure of the galvanized steel sheet which concerns on the modification of this invention, and is the cross-sectional view along the plate thickness direction. This is an example of a line profile showing the surface shape of a galvanized steel sheet according to a modified example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.
The "%" indication of the content of each element in the chemical composition means "mass%".
The numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
The numerical range when "greater than" or "less than" is added to the numerical values before and after "~" means a range in which these numerical values are not included as the lower limit value or the upper limit value.
The term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.

The galvanized steel sheet according to the embodiment of the present invention is
Steel plate and
A zinc-based plating layer located on at least one surface of the steel sheet and having a hairline formed as a recess extending in a predetermined direction.
An oxide layer located on the surface of the zinc-based plating layer and having an average thickness of 0.05 μm or more and 3.0 μm or less.
To be equipped.

Due to the above configuration, the galvanized steel sheet according to the present embodiment has good corrosion resistance, good blackness and hairline appearance, metallic feeling and processing even when an inexpensive steel material is used. A galvanized steel sheet with excellent adhesion.
The galvanized steel sheet according to this embodiment was found based on the following findings.

In the prior art, a black pigment is added to an organic resin coating layer provided on a zinc-based plating layer on which a hairline is formed, and the film thickness of the organic resin coating layer and the concentration of the black pigment are adjusted to obtain a zinc-based plated steel sheet. It is black and has a hairline appearance, and gives a metallic feel. In this case, there is a trade-off relationship between the blackness and the appearance of the hairline and the addition of a metallic feeling. When the blackness is increased, the hiding property of the organic resin coating layer is increased, so that the hairline formed on the surface of the plating layer becomes invisible and the metallic feeling is also lowered.

Therefore, the present inventors have diligently studied a method for improving the blackness, hairline appearance and metallic feeling of a galvanized steel sheet having a predetermined corrosion resistance while using an inexpensive steel material. As a result, if an oxide layer is formed on the surface layer of the zinc-based plating layer with an average thickness of 0.05 μm or more that exhibits black color, the blackness is improved and the hairline formed on the zinc-based plating layer is not concealed. , It was found that the appearance of hairline and metallic feeling can be improved.
However, it was also found that when the oxide layer has an average thickness of 3 μm or less, cracks are suppressed in the oxide layer and the processing adhesion between the zinc-based plating layer and the organic resin coating layer is improved.

From the above findings, the galvanized steel sheet according to the embodiment of the present invention has good corrosion resistance, good blackness and hairline appearance even when an inexpensive steel material is used due to the above configuration. In addition, it was found that a galvanized steel sheet having excellent metallic feeling and processing adhesion was obtained.

Further, the present inventors diligently studied a method for improving the metallic feeling, and if it is possible to control the particle size of the oxide in the oxide layer formed on the surface layer of the zinc-based plating layer, the plating layer. It was considered that even when the upper layer was coated with resin, it was possible to improve the metallic feeling with black color. As a result of further studies based on this idea, the present inventors have obtained the following findings.
In order to suppress diffused reflection that occurs on the surface of the oxide layer, it has been found that diffused reflection can be suppressed by providing a smooth portion that reduces the unevenness of the crystal particles of the plating layer before forming the oxide layer. rice field. On the other hand, on the surface of the plating layer, the portion where the unevenness of the crystal particles of the plating layer remains becomes a rough portion, and the particle size of the oxide formed on the surface also increases. The presence of the oxide particles having a large particle size improves the processing adhesion. As a result, processing adhesion with the resin coating layer can be obtained.
Therefore, it was found that by appropriately adjusting the ratio of the rough portion and the smooth portion, both the metallic feeling and the processing adhesion can be obtained. It was also confirmed that when the oxide layer is thin, it is affected by the surface roughness of the plating layer.

Based on the above-mentioned various findings, the present inventors have diligently studied the ratio of the rough portion and the smooth portion, and even when the organic resin coating layer is present in the upper layer of the oxide layer, the blackness We have come up with suitable conditions for achieving both a metallic feeling, processing adhesion between the organic resin coating layer and the zinc-based plating layer, and a hairline appearance.

Based on this finding, in the galvanized steel sheet according to the embodiment of the present invention,
The oxide layer is composed of a rough portion (A) and a smooth portion (B).
The rough portion (A) _{includes a region having a surface roughness Ra A} of more than 500 nm and 5000 nm or less.
The smooth portion (B) _{includes a region having a surface roughness Ra B} of more than 5 nm and 500 nm or less.
The boundary between the rough portion (A) and the smooth portion (B) is within an observation width of 1 cm along the hairline orthogonal direction in a cross section in the hairline orthogonal direction orthogonal to the predetermined direction and in the plate thickness direction. When it is assumed that the height is 1/3 of the maximum height Ry obtained by subtracting the minimum point H _{0 from the highest point H 1} of the oxide layer in the above and is on a virtual straight line parallel to the hairline orthogonal direction, the coarseness is assumed. the smoothing section and the section (a) and the oxide layer plan view in which the boundary is defined in (B), and the same unit of area from each other, the rough portions of the area of (a) and S _a, the smoothing unit ( the area of B) when the _{S B,} the area ratio _S B / _{S a} is in the range of 0.6 to 10.0,
The average height difference between the rough portion (A) and the smooth portion (B) adjacent to the rough portion (A) is preferably 0.3 μm to 5.0 μm.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

(About the overall composition of galvanized steel sheet)
In the following, first, with reference to FIGS. 1A and 1B, the overall configuration of the zinc-based electroplated steel sheet according to the embodiment of the present invention will be described in detail. 1A and 1B are explanatory views schematically showing an example of the structure of the galvanized steel sheet according to the present embodiment.

As is schematically shown in FIG. 1A, the zinc-based plated steel sheet 1 according to the present embodiment includes a steel sheet 11 as a base material, a zinc-based plating layer 13 located on one surface of the steel sheet 11, and zinc-based plating. It has at least an oxide layer 14 located on the surface of the layer 13.
Further, as shown in FIG. 1B, the zinc-based plated steel sheet 1 according to the present embodiment further has a translucent organic resin coating layer 15 on the surface side of the zinc-based plated layer 13. preferable. In particular, having the organic resin coating layer 15 is preferable from the viewpoint of ensuring fingerprint resistance, processability, and corrosion resistance.

<About the base material>
The steel sheet 11 which is the base material of the galvanized steel sheet according to the present embodiment is not particularly limited, and is known depending on the mechanical strength (for example, tensile strength, etc.) required for the galvanized steel sheet. Various steel materials (mild steel, ordinary steel, high-strength steel, etc.) can be appropriately used.

<About zinc-based plating layer>
A zinc-based plating layer 13 is formed on at least one surface of the steel plate 11.
As schematically shown in FIG. 1A, the zinc-based plating layer 13 has a recess 101 forming a hairline extending in a predetermined direction (in the case of FIG. 1A, the direction perpendicular to the paper surface), and a non-hairline portion 103. doing.
In the zinc-based plating layer 13, a rough portion as described in detail below is formed in the recess 101 forming the hairline, and a smooth portion as described in detail below is formed in the non-hairline portion 103. You may. Alternatively, in the zinc-based plating layer 13, a smooth portion of the oxide layer 14 as described in detail below is formed in the recess 101 forming the hairline, and the non-hairline portion 103 is described in detail below. Such a rough portion of the oxide layer 14 may be formed. In any case, the average length along the stretching direction of the hairline is preferably 1 cm or more.

The hairline depth (hairline depth after forming the oxide layer 14 on the surface of the zinc-based plating layer 13) is exemplified in the range of 0.2 μm or more and 2.5 μm or less. Further, the cross-sectional shape of the hairline in the cross section orthogonal to the extending direction of the hairline is mainly V-shaped, but may include a U-shape.

In the following description, the "direction in which the hairline is extended" is abbreviated as "hairline direction", and the "direction orthogonal to the extension direction of the hairline" is abbreviated as "hairline orthogonal direction". .. Further, the above-mentioned rough portion and smooth portion will be described in detail below.

[Type and composition of zinc-based plating layer]
As the zinc-based plating layer 13, for example, a zinc-based electroplating layer (electrozinc plating layer, electrozinc alloy plating layer) and a zinc-based hot-dip plating layer (fused zinc plating layer, hot-dip zinc alloy plating layer) are used. Hereinafter, the zinc-based electroplating layer and the zinc-based hot-dip plating layer may be described with reference to reference numeral 13.

First, regarding the plating metal of the zinc-based plating layer 13, plating other than zinc-based plating is inferior in sacrificial corrosion resistance, and therefore is not suitable for applications in which the cut end face is inevitably exposed during use. Further, if the zinc concentration in the plating layer becomes too low, the sacrificial anticorrosion ability is lost. Therefore, the zinc alloy plating preferably contains 35% by mass or more of zinc with respect to the total mass of the plating layer.

Specifically, the Zn content in the zinc-based plating layer 13 is preferably 35% by mass or more, more preferably 70% by mass or more, and particularly preferably 70% by mass or more, based on the total mass of the plating layer. Is 80% by mass or more. On the other hand, the upper limit of the Zn content in the zinc-based plating layer is 100% by mass.

Further, as the plating method, there are an electroplating method, a hot-dip plating method, a thermal spraying method, a vapor deposition plating method and the like. However, the thermal spraying method may not be suitable because the uniformity of appearance cannot be ensured due to the voids inside the plating layer. In addition, the vapor deposition method may be unsuitable because the film formation rate is slow and the productivity is poor. Therefore, in the zinc-based plated steel sheet 1 according to the present embodiment, it is preferable to use an electroplating method or a hot-dip plating method in order to apply zinc-based plating to the surface of the steel sheet.

Here, the electrozinc alloy plating layer contains at least one additive element selected from the element group consisting of Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, and Zr, and Zn. And, preferably.
In particular, the electrozinc alloy plating layer preferably contains at least one additive element selected from the element group consisting of Fe, Ni, and Co in a total of 5% by mass or more and 20% by mass or less. That is, the zinc-based electroplating layer contains a total of 5% by mass to 20% by mass of any one or more additive elements selected from the group consisting of Fe, Ni, and Co, and a balance composed of Zn and impurities. Is preferably contained. When the electrozinc alloy plating layer contains at least one of Fe, Ni, and Co additive elements within the above total content range, more excellent corrosion resistance (white rust resistance / barrier property) is realized. It becomes possible.

Further, the electrogalvanized layer and the electrogalvanized alloy plated layer may contain impurities as a balance. Here, the impurities are not intentionally added as a component of the zinc-based electroplating layer, but are mixed in the raw material or are mixed in the manufacturing process, and are Al, Mg, Si, Ti. , B, S, N, C, Nb, Pb, Cd, Ca, Pb, Y, La, Ce, Sr, Sb, O, F, Cl, Zr, Ag, W, H and the like. Further, when performing electrogalvanization, although it depends on the type of electroplated steel sheet manufactured in the same manufacturing facility, Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, Zr, etc. may be mixed as impurities. However, even if impurities are present in a total amount of about 1% by mass with respect to the total mass of the plating, the effect obtained by the plating is not impaired.
The intentionally added Fe, Ni, and Co and the Fe, Ni, and Co mixed as impurities can be distinguished from each other by the concentration in the zinc-based electroplating layer 13. That is, for example, since the lower limit of the total content of Fe, Ni, and Co when added intentionally is 5% by mass, if the total content is less than 5% by mass, it can be discriminated as an impurity.

The composition of the zinc-based electroplating layer as described above can be analyzed by, for example, the following method. That is, the average composition of the plating layer is determined by analyzing with an electron probe microanalyzer (EPMA) from the cross-sectional direction along the plate thickness direction. At this time, the oxide layer formed on the surface of the plating layer is excluded. Whether or not it is an oxide layer is determined by the oxygen concentration. If the oxygen concentration is 20% by mass or more, it is judged to be an oxide layer.

[About the average amount of adhesion of the zinc-based electroplating layer]
The average adhesion amount of the zinc-based electroplating layer 13 ^{is preferably 5 g / m 2} or more and 40 g / m ² or less. If the average adhesion amount of the zinc-based electroplating layer 13 is ^{less than 5 g / m 2} , the base iron (that is, the steel plate 11) may be exposed when the hairline is applied. On the other hand, when the average adhesion amount of the zinc-based electroplating layer 13 ^{exceeds 40 g / m 2} , the hairline formed on the steel sheet 11 by grinding or rolling may be less noticeable by the zinc-based electroplating layer 13. , Not preferable. The lower limit of the average adhesion amount of the zinc-based electroplating layer 13 is more preferably 7 g / m ² and even more preferably 10 g / m ² . The upper limit of the average adhesion amount of the zinc-based electroplating layer 13 is more preferably 35 g / m ² or less, and further preferably 30 g / m ² .

The zinc-based hot-dip galvanizing layer includes a "hot-dip galvanizing layer" or a "hot-dip zinc alloy plating layer".
The hot-dip galvanized layer is composed of, for example, zinc and elements such as Al, Sb, and Pb having a total balance of less than 5% by mass.
The molten zinc alloy plating layer is composed of, for example, zinc and an alloy element having a total of 1% by mass or more in the balance. As the alloy element group, at least one element selected from Fe, Al, Mg, Si and the like is selected. In particular, the molten zinc alloy plating layer preferably contains at least one selected from the group consisting of Al and Mg in a total amount of 1% by mass or more and 60% by mass or less. That is, the zinc-based hot-dip plating layer contains 1% by mass to 60% by mass in total of any one or more additive elements selected from the group consisting of Al and Mg, and a balance composed of Zn and impurities. It is preferable to do so. When the molten zinc alloy plating layer is contained within the above total content range, it is possible to realize more excellent corrosion resistance (white rust resistance / barrier property).

Further, the hot-dip galvanized layer and the hot-dip zinc alloy plated layer may contain impurities as a balance. Here, the impurities are not intentionally added as zinc-based hot-dip plating components, but are mixed in the raw material or mixed in the manufacturing process, and are mixed in Al, Mg, Si, Ni, Ti. , Pb, Sb and the like. However, even if impurities are present in a total amount of about 1% by mass with respect to the total mass of the plating, the effect obtained by the plating is not impaired.
The intentionally added alloying element and the element mixed as an impurity can be distinguished from each other by the concentration in the zinc-based hot-dip plating layer 13. That is, for example, since the lower limit of the total content of Al and Mg when intentionally added is 1% by mass, if the total content is less than 1% by mass, it can be discriminated as an impurity.

The composition of the zinc-based hot-dip plating layer as described above can be analyzed by, for example, the same method as the method for analyzing the composition of the zinc-based electroplating layer described above.

[About the average amount of adhesion of the zinc-based hot-dip plating layer 13]
The average adhesion amount of the zinc-based hot-dip plating layer 13 is preferably more ^{than 40 g / m 2 and} 150 g / m ^{2 or less.} When the average adhesion amount of the zinc-based hot-dip plating layer 13 is 40 g / m ² or less, it is necessary to increase the gas pressure during gas wiping to control the adhesion amount after hot-dip plating, and a uniform plating adhesion amount can be obtained. May not be available. On the other hand, when the average adhesion amount of the zinc-based hot-dip plating layer 13 ^{exceeds 150 g / m 2} , it is necessary to reduce the plate passing speed, which is not preferable because the productivity is lowered.
The lower limit of the average adhesion amount of the zinc-based hot-dip plating layer 13 is more preferably 45 g / m ² or more, and further preferably 50 g / m ² or more. The upper limit of the average adhesion amount of the zinc-based hot-dip plating layer 13 is more preferably 120 g / m ² or less, and further preferably 90 g / m ² or less.

<About the oxide layer>
The surface of the zinc-based plating layer 13 provided with the hairline is covered with the oxide layer 14 as schematically shown in FIG. 1A. That is, the oxide layer 14 is provided along the surface texture of the zinc-based plating layer 13, and the oxide layer 14 is also provided with a hairline. The galvanized steel sheet has a high degree of blackness due to having such an oxide layer 14. In the present application, the oxide layer 14 is located at least on the surface of the zinc-based plating layer 13 other than the recesses.

The average thickness of the oxide layer 14 is 0.05 μm or more and 3.0 μm or less. When the average thickness of the oxide layer 14 is less than 0.05 μm, sufficient blackness cannot be obtained, and the hairline and metallic feeling are deteriorated. On the other hand, when the average thickness of the oxide layer 14 exceeds 3.0 μm, the oxide layer 14 is cracked by the processing, and the processing adhesion is lowered.
The lower limit of the average thickness of the oxide layer 14 is more preferably 0.07 μm, further preferably 1.0 μm. The upper limit of the average thickness of the oxide layer 14 is preferably 2.7 μm, more preferably 2.5 μm.

The average thickness of the oxide layer is measured as follows.
A sample cut along the plate thickness direction is collected from the galvanized steel sheet. Then, the cross section (cross section along the plate thickness direction) of the plating layer and the oxide layer is observed with a transmission electron microscope (TEM-EDS) equipped with an energy dispersive X-ray analyzer (EDS) to remove oxygen elements. Map. Next, a region having an oxygen concentration of 20% by mass or more existing from the surface toward the plating layer is defined as an oxide layer, and the thickness of the oxide layer is measured at a plurality of locations. Then, the average value of the thicknesses of the oxide layers measured at a plurality of locations is calculated.

The oxide layer 14 is composed of, for example, a Zn-based oxide or a hydroxide. However, oxides or hydroxides derived from alloying elements other than Zn may be contained.
Specific examples of Zn-based oxides or hydroxides include ZnO, ZnO _1-x , Zn (OH) _{2, and the} like.
As a method for forming the oxide layer 14, well-known methods such as acid immersion treatment and Zn oxide treatment are exemplified.

[About organic resin coating layer]
As schematically shown in FIG. 1B, it is preferable that the surface of the oxide layer 14 to which the hairline is provided is provided with a translucent organic resin coating layer 15.
Here, the fact that the organic resin coating layer 15 has translucency (transparency) means that the oxide layer 14 can be visually observed through the organic resin coating layer 15 formed on the surface. In addition, in this specification, "translucency" and "transparency" are used in the same meaning.

The resin used for forming the organic resin coating layer 15 is preferably one having sufficient transparency, chemical resistance, corrosion resistance, processability, scratch resistance and the like. Examples of such resins include polyester resins, epoxy resins, urethane resins, polyester resins, phenol resins, polyether sulfone resins, melamine alkyd resins, acrylic resins, polyamide resins, and polyimides. Based resins, silicone resins, polyvinyl acetate resins, polyolefin resins, polystyrene resins, vinyl chloride resins, vinyl acetate resins and the like can be used.

In order to add desired performance to the organic resin coating layer 15, various additives are contained in the organic resin coating layer 15 within a range that does not impair transparency and appearance and does not deviate from the range specified in the present invention. You may let me. Examples of the performance added to the organic resin coating layer 15 include corrosion resistance, slidability, scratch resistance, conductivity, and color tone. For example, if it is corrosion resistant, it may contain a rust preventive or an inhibitor, if it is slidable or scratch resistant, it may contain wax or beads, and if it is conductive, it may contain a conductive agent. And the like may be contained, and if it is a color tone, a known colorant such as a pigment or a dye may be contained.

When the organic resin coating layer 15 according to the present embodiment contains a known colorant such as a pigment or a dye, it is preferable to contain the colorant to such an extent that the hairline can be visually recognized.
Examples of the colorant include Bengara, aluminum, mica, carbon black, titanium oxide, cobalt blue and the like. The content of the colorant is preferably 1 to 10% by mass, more preferably 2 to 5% by mass, based on the organic resin coating layer 15.

[Thickness of organic resin coating layer]
The average thickness of the organic resin coating layer 15 is preferably 10 μm or less. When the average thickness of the organic resin coating layer 15 exceeds 10 μm, the distance through which the light passes through the organic resin coating layer 15 becomes long, so that the reflected light is reduced and the glossiness is likely to be lowered. Further, due to the deformation of the resin due to the processing, the texture of the surface of the zinc-based plating layer 13 and the shape of the surface of the organic resin coating layer 15 are likely to deviate from each other. For the above reasons, the average thickness of the organic resin coating layer 15 is preferably 10 μm or less, and more preferably 8 μm or less.

On the other hand, from the viewpoint of corrosion resistance, the thickness of the thinnest portion of the organic resin coating layer 15 when viewed from the cross section (that is, the minimum value of the thickness of the organic resin coating layer 15) is 0.1 μm or more and is coated with the organic resin. The average thickness of the layer 15 is preferably 1.0 μm or more. Here, the "thinnest part" means the minimum value of the film thickness measured at 20 points at 100 μm intervals by cutting out a length of 5 mm at an arbitrary position in the direction orthogonal to the hairline to prepare a cross-sectional sample. However, the "average thickness" means the average of 20 points. It is more preferable that the thickness of the thinnest portion of the organic resin coating layer 15 is 0.5 μm or more, and the average thickness of the organic resin coating layer 15 is 3.0 μm or more.

The overall configuration of the galvanized steel sheet 1 according to the present embodiment has been described in detail above. Although FIGS. 1A and 1B show a case where the zinc-based plating layer 13, the oxide layer 14, and the organic resin coating layer 15 are formed on one surface of the steel sheet 11, the front and back sides of the steel sheet 11 are shown. A zinc-based plating layer 13 and an organic resin coating layer 15 may be formed on the two surfaces.

(About the surface shapes of the zinc-based electroplating layer 13 and the oxide layer 14)
Next, the surface shapes of the zinc-based plating layer 13 and the oxide layer 14 according to the present embodiment will be described in detail with reference to FIGS. 2 to 6. FIG. 2 is an explanatory diagram for explaining an example of a zinc-based plating layer and an oxide layer according to the present embodiment. 3 to 5 are graphs for explaining an example of the zinc-based plating layer and the oxide layer according to the present embodiment. FIG. 6 is an explanatory diagram for explaining another example of the zinc-based plating layer and the oxide layer 14 according to the present embodiment.

As mentioned earlier, the zinc-based plating layer 13 has a recess 101 forming a hairline and a non-hairline portion 103 on the surface layer portion. The oxide layer 14 also has a recess 101 forming a hairline and a non-hairline portion 103 along the surface texture of the zinc-based plating layer 13. That is, the oxide layer 14 has a hairline corresponding to the hairline of the zinc-based plating layer 13.
Focusing on the surface shape of the micro-oxide layer 14 that is different from the hairline, the oxide layer 14 has a _{rough portion 111 including a region having a surface roughness Ra A} of more than 500 nm and 5000 nm or less, and a surface roughness Ra. _It has a smoothing portion 113 including a region where B is more than 5 nm and 500 nm or less.

In the oxide layer 14, the rough portion 111 as described above may be formed in the hairline, or the smooth portion 113 as described above may be formed in the hairline. That is, the rough portion 111 as described above may be formed in the recess 101 forming the hairline, and the smooth portion 113 as described above may be formed in the non-hairline portion 103. .. Alternatively, the smooth portion 113 as described above may be formed in the recess 101 forming the hairline, and the rough portion 111 as described above may be formed in the non-hairline portion 103. ..

Here, the area ratio of the rough portion and the smooth portion in the oxide layer 14 is determined by observing the actual surface state with a scanning electron microscope (SEM) or the like and measuring each area ratio. It is also possible, but as will be described later, the roughness profile is measured with a laser microscope, the rough portion corresponding portion and the smooth portion corresponding portion are set by the boundary line by the virtual straight line based on the measurement, and the area ratio thereof is used.
The boundary line between the rough portion 111 and the smooth portion 113 in the oxide layer 14 is defined as follows.
First, as shown in FIGS. 2 and 9A, in the oxide layer 14, the rough portion 111 is formed in the recess 101 forming the hairline, and the smooth portion 113 is mainly formed in the non-hairline portion 103. Focus on the case. In this case, a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more (that is, a laser microscope having a display resolution in the height direction and the width direction better than 1 nm). Is used to measure the surface height of the oxide layer 14 in a range of 1 cm × 1 cm in a plan view at a magnification of 500 times. When the observation field of view of the laser microscope is less than 1 cm, a plurality of fields of view may be observed and these may be connected to measure the surface height.

Next, the surface height of the cross section (FIG. 9A) in the direction orthogonal to the hairline and in the plate thickness direction is plotted at 100 μm intervals along the hairline direction, and the lowest point (H ₀ ) and the highest height in the cross section are plotted. Each point (H ₁ ) is specified. The “smoothing portion 113” is a region defined by a set of points whose _{height from the lowest point (H 0} ) is (H ₁ −H _{0) × 1/3 or more.} On the other hand, the "coarse portion 111" is a region defined by a set of points whose height from the _{lowest point (H 0 ) is less than (H 1} −H _{0) × 1/3.} That is, the boundary between the rough portion 111 and the smooth portion 113 is an oxide layer within an observation width of 1 cm along the hairline orthogonal direction in each of the cross sections in the hairline orthogonal direction and the plate thickness direction (FIG. 9A). It exists on a virtual straight line BL which is 1/3 of the maximum height Ry obtained by subtracting the lowest point H ₀ from the highest point H _{1 of 14 and is parallel to the hairline orthogonal direction.}

The rough portion 111 corresponds to a portion that has not been affected by processing such as grinding or rolling after the oxide layer 14 is formed. Therefore, when the surface of the oxide layer 14 is observed under a microscope, oxide particles having a height can be confirmed in the rough portion 111 of the oxide layer 14.

_{The average particle size Dave} indicating the size of the oxide particles of the oxide layer 14 can be obtained by the following method.
First, the surface of the oxide layer 14 is observed by SEM. The visual field magnification at that time is within the range of 1000 to 10000 times, but if the oxide particles cannot be confirmed even at the maximum magnification of 10000 times, the number is counted as zero. Subsequently, the flat area S per oxide particle is obtained from the contour of the oxide particles. Then, assuming a circle having the same flat area as the flat area, the diameter is obtained as the representative diameter D by the following formula (1). _{Then, the average particle size Dave} can be obtained by arbitrarily selecting 10 oxide particles in the observation field of view and obtaining the average value of the representative diameters D of the 10 oxide particles.

D = 2 × (S / π) ^0.5 ... Equation (1)
Here, D is a representative diameter of the oxide particles in a plan view, and the unit thereof is μm. Further, S is a circular equivalent area of the oxide particles in a plan view, and the unit thereof is μm ² .

The density of oxide particles is determined by the following method.
First, as described above, the surface of the oxide layer 14 is observed by SEM, and the density of the oxide particles is obtained by counting the number of oxide particles above the particle size threshold within the range of 100 μm × 100 μm. Be done. The particle size threshold differs depending on the plating type and alloy of the lower zinc-based plating layer 13, and is, for example, 0.1 μm to 3.0 μm when the lower zinc-based plating layer 13 is a Zn—Ni electroplating layer. Values within the range, values within the range of 0.3 μm to 3.6 μm for the Zn-Fe electroplating layer, and values within the range of 0.4 μm to 9.6 μm for the Zn-Co electroplating layer. Often.
If the oxide particles cannot be confirmed even when the SEM magnification is set to the maximum magnification (10000 times), the number is counted as zero.

When the zinc-based plating layer 13 is Zn-Fe electroplated layer, the average particle diameter _{D ave} of the oxide particles in the coarse portion 111 will be in the range of 0.5Myuemu～2.7Myuemu. Further, the density of the oxide particles in the rough portion 111 is in the range of 2 × 10 ¹⁰ particles / m ^{2 to} 5 × 10 ¹⁴ particles / m ² . As an example of the measured values, when the zinc-based plating layer 13 is a Zn—Fe electroplating layer, the oxide particles in the rough portion 111 have an average particle size _Dave of 2.1 μm and a density of 5 × 10 ^13. It was ² pieces / m 2.

Furthermore, if a zinc-based plating layer 13 is Zn-Co electroplated layer, the average particle diameter D _ave of the oxide particles in the coarse portion 111 will be in the range of 0.6Myuemu～7.2Myuemu. The density of the oxide particles in the rough portion 111 is in the range of 0.5 × 10 ¹⁰ particles / m ^{2 to} 3.6 × 10 ¹⁴ particles / m ² . As an example of the measured value, when the zinc-based plating layer 13 is a Zn—Co electroplating layer, the oxide particles in the rough portion 111 have an average particle size _Dave of 6.2 μm and a density of 2.0 ×. It was 10 ¹² pieces / m ² .

Furthermore, if a zinc-based plating layer 13 is Zn-Ni electroplating layer, the average particle diameter D _ave of the oxide particles in the coarse portion 111 will be in the range of 0.3Myuemu～2.4Myuemu. The density of the oxide particles in the rough portion 111 is in the range of 5 × 10 ¹⁰ particles / m ^{2 to} 8.4 × 10 ¹⁴ particles / m ² . As an example of the measured value, when the zinc-based plating layer 13 is a Zn—Ni electroplating layer, the oxide particles in the rough portion 111 have an average particle size _Dave of 0.7 μm and a density of 4.0 ×. It was 10 ¹² pieces / m ² .

Summarizing the above, when the zinc-based plating layer 13 is a zinc-based electroplating layer and contains any one or more elements selected from the group consisting of Fe, Ni, and Co as additive elements, it is coarse. The density of oxide particles having a particle size of 0.3 μm or more in part 111 is 10 ¹⁰ particles / m ² or more.

Next, as shown in FIGS. 6 and 9B, in the oxide layer 14, the smooth portion 113 is formed in the recess 101 forming the hairline, and the rough portion 111 is mainly formed in the non-hairline portion 103. Pay attention to the case. In this case, a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more (that is, a laser microscope having a display resolution in the height direction and the width direction better than 1 nm). Is used to measure the surface height of the oxide layer 14 in a range of 1 cm × 1 cm in a plan view at a magnification of 500 times. When the observation field of view of the laser microscope is less than 1 cm, a plurality of fields of view may be observed and these may be connected to measure the surface height.

Next, the surface height of the cross section in the hairline orthogonal direction and the plate thickness direction is plotted at 100 μm intervals along the hairline direction, and the lowest point (H ₀ ) and the highest point (H _{1) of the height in the cross section are plotted.} ) Are specified respectively. The “coarse portion 111” is a region defined by a set of points whose _{height from the lowest point (H 0} ) is (H ₁ −H _{0) × 1/3 or more.} On the other hand, the “smoothing portion 113” is a region defined by a set of points whose height from the _{lowest point (H 0 ) is less than (H 1} −H _{0) × 1/3. Then, the boundary between the rough portion 111 and the smooth portion 113 is the highest point H 1} of the oxide layer 14 within the range of the observation width of 1 cm along the hairline orthogonal direction in each cross section in the hairline orthogonal direction and the plate thickness direction. It exists on a virtual straight line BL that is 1/3 of the maximum height Ry obtained by subtracting the lowest point H _{0 from the height and is parallel to the hairline orthogonal direction.}

In the oxide layer 14, the rough portion 111 as described above corresponds to the portion where the unevenness of the crystal particles of the plating layer in the lower layer exists, and the smooth portion 113 as described above is lower than the rough portion 111. Corresponds to the part where the unevenness of the crystal particles in the plating layer is small.
In the oxide layer 14, the rough portion 111 in which the irregularities of the oxide particles are present and the smooth portion 113 in which the irregularities of the oxide particles are smaller than the rough portion 111 are present in an appropriate ratio. As a result, the smooth portion 113 realizes an improvement in metallic feeling, and the rough portion 111 realizes processing adhesion with the organic resin coating layer 15 which is preferably provided on the upper layer of the oxide layer 14.

Hereinafter, various conditions required for the oxide layer 14 will be described in detail in order to achieve both a metallic feeling and processing adhesion even when the organic resin coating layer 15 is present on the oxide layer 14. .. In the following, the case where the rough portion 111 is formed in the recess 101 forming the hairline and the smooth portion 113 is formed in the non-hairline portion 103 will be described as an example.

[Difference between the average surface height of the rough part and the average surface height of the smooth part]
Since the oxide layer 14 has both the rough portion 111 and the smooth portion 113 as described above, as is schematically shown in FIG. 2, the rough portion 111 and the smooth portion 113 adjacent to each other For each, the average surface height of the rough portion 111 and the average surface height of the smooth portion 113 can be considered. At this time, in the oxide layer 14, the average height difference between the rough portion 111 and the smooth portion 113 adjacent to the rough portion 111 (the average surface height of the rough portion 111 and the smooth portion 113 adjacent to the rough portion 111). The difference) is in the range of 0.3 μm to 5.0 μm. That is, in the oxide layer 14, when substantially all of the recesses 101 forming the hairline are rough portions 111 and substantially all of the non-hairline portions 103 are smooth portions 113, the average height between the recesses 101 and the non-hairline portions 103 is high and low. The difference is also in the range of 0.3 μm to 5.0 μm.

For example, in the example shown in FIG. 2, a rough portion A ₂ formed in the recess 101 to form a hairline, the smoothing unit B ₃ formed in the non hairline unit 103, are adjacent to each other, crude The average height difference between the portion A ₂ and the smooth portion B ₃ can be specified by a known measuring method. At this time, the height difference (Δh in FIG. 2) between the average surface height of the smooth portion B _{3 and} the average surface height of the rough portion A _{2 is within the range of 0.3 μm to 5.0 μm.} Further, the same relationship is established between the rough portion A ₂ and the smooth portion B ₂ , between the rough portion A ₁ and the smooth portion B _2, and between the rough portion A ₁ and the smooth portion B _1. doing.

When the average height difference between the smooth portion 113 and the rough portion 111 adjacent to each other is less than 0.3 μm, the hairline becomes inconspicuous, and it is useless to perform the hairline processing on the zinc-based plating layer 13 and the oxide layer 14. .. On the other hand, when the average height difference between the smooth portion 113 and the rough portion 111 adjacent to each other exceeds 5.0 μm, the hairline becomes too coarse to be a beautiful hairline, and the design as a hairline is impaired. The lower limit of the average height difference between the smooth portion 113 and the coarse portion 111 adjacent to each other is preferably 0.8 μm, more preferably 1.0 μm. The upper limit of the average height difference between the smooth portion 113 and the rough portion 111 adjacent to each other is preferably 2.6 μm, more preferably 2.2 μm.

The average height difference between the rough portion 111 and the smooth portion 113 can be measured, for example, by measuring the surface of the oxide layer 14 with a laser microscope. At this time, at each of the plurality of locations of the oxide layer 14, the difference Δh between the average surface height h1 of a certain rough portion 111 and the average surface height h2 of the smooth portion 113 adjacent to the rough portion 111 is set. Ask. Then, 20 or more sets of differences Δh of the combination of the rough portion 111 and the smooth portion 113 are obtained, and the average value thereof is set as “the average height difference between the rough portion 111 and the smooth portion 113”.
Here, the average surface height h1 of the rough portion 111 is an average value of the maximum height and the minimum height of the rough portion 111 between the boundaries with the smooth portion 113. Similarly, the average surface height h2 of the smooth portion 113 is the average value of the maximum height and the minimum height of the smooth portion 113 between the boundary with the rough portion 111.

[Area ratio of rough area to smooth area]
When the oxide layer in which the boundary between the rough portion 111 and the smooth portion 113 is defined is viewed in a plan view (observed from the plate thickness direction), the area of the rough portion 111 (the area corresponding to the rough portion 111) in the oxide layer 14 total plane area) as _{S a,} the area of the smooth portion 113 (total plane area of the area corresponding to the smooth portion 113) is taken as _{S B,} the area ratio _S B / _{S a} in the same unit of area from each other, 0 It is within the range of 6.6 or more and 10.0 or less. In this case, for example, in the range shown in FIG. 2, the total plane area of the area and the coarse portion A ₂ of the coarse portion A ₁ is the area S _A becomes coarse portion 111 within the range shown in FIG. 2, total area of the smooth portion B ₁ of the area and the smooth portion B ₂ of the area and the smooth portion B ₃ becomes the area S _B of the smooth portion 113 within the range shown in FIG. The flat area is the area when the oxide layer 14 is viewed in a plan view as shown in FIG. 8 (specifically, when the surface of the oxide layer 14 is viewed as an image when observed with an electron microscope. Area).

Hereinafter, the reason why the area ratio S _{B /} S _A as described above is important, with reference to FIGS. 3 to 5 will be specifically described.

In FIG. 3, _{after fixing the value of the area ratio S B} / S _A to 2.0, the surface roughness Ra _B of the smooth portion 113 (arithmetic mean roughness Ra specified in JIS B 0601 (2001)) is obtained. It shows the result of measuring 60 degree gloss (G60) using a commercially available gloss meter when changed. 3, the horizontal axis is the surface roughness R _B of the smoothing unit 113, the vertical axis is the measurement result of the 60 degree gloss. Further, FIG. 3 shows measurement results in each of the hairline stretching direction (hereinafter, hairline direction) and the direction orthogonal to the hairline (hereinafter, hairline orthogonal direction).

As is clear from FIG. 3, in the measurement results in both the hairline direction and the hairline orthogonal direction, the _{larger the surface roughness Ra B} of the smooth portion 113 (in other words, the more the smoothness is lost from the smooth portion 113). ), It can be seen that the value of the 60-degree gloss decreases and the metallic feeling decreases. From these results, it can be seen that by providing the smoothing portion 113, it is possible to suppress diffused reflection of light reaching the surface of the oxide layer 14 and improve the glossiness.

Next, FIG. 4, by adjusting the surface roughness Ra _B of the smoothing part 113 to 20 ± 5 nm, in the case of changing the area ratio _S B / _{S A,} with a commercially available gloss meter, 60 degrees It shows the result of having measured the gloss (G60). 4, the horizontal axis is the area ratio _S B / _{S A,} the vertical axis is the measurement result of the 60 degree gloss.

As is clear from FIG. 4, by setting the area ratio S _B / S _A to 0.6 or more, compared with the case where the smoothing portion 113 is not provided (when the area ratio S _B / S _A = 0). , It is possible to realize a glossiness of about 5 times or more in the hairline direction, and it is possible to realize a glossiness of about 3 times or more in the direction orthogonal to the hairline.

On the other hand, FIG. 5 shows the result of providing the organic resin coating layer 15 on the surface of the sample similar to that used for the measurement of FIG. 4 and evaluating the processing adhesion thereof. The processing adhesion is evaluated in the same manner as the method described in the following examples, and is performed in five stages from a score 5 meaning excellent processing adhesion to a score 1 meaning inferior processing adhesion. evaluated. As is clear from FIG. 5 _{, in the sample having the area ratio S B} / S _A of 10 or less, the processing adhesion was evaluated as a score of 5, whereas the sample _{having the area ratio S B} / S _{A exceeding 10 was evaluated.} Then, the processing adhesion was lowered.

Further, the same measurement as in FIGS. 4 and 5 was carried out while changing _{the surface roughness Ra B} of the smooth portion 113 in the range of 5 nm to 500 nm. Even in that case, by _{setting the area ratio S B} / S _A to 0.6 or more, it is dramatically superior to the case where the smoothing portion 113 is not provided (when the area ratio S _B / S _{A = 0).} can be realized glossiness, the area ratio S _{B /} S _a is greater than 10, processability adhesion is lowered.

From the above results, in the oxide layer 14, the area ratio _S B / _{S A} that is preferably in the range of 0.6 to 10.0, revealed. In the oxide layer 14, the lower limit of the area ratio _S B / _{S A} is preferably 1.5, more preferably 2.5. The upper limit of the area ratio S _B / S _A is preferably 8.0, more preferably 6.5.

Here, (a total plane area of the region corresponding to the coarse portion 111) _{S A} area of the coarse portion 111, and the _{S B} (total plane area of the area corresponding to the smooth portion 113) the area of the smooth portion 113, the height The height data measured by a laser microscope having a display resolution in the direction of 1 nm or more and a display resolution in the width direction of 1 nm or more is binarized, and the obtained binarized data is subjected to known image processing. It can be measured by applying.

Incidentally, as described above, the average height difference between the coarse portion 111 and the smoothing unit 113, and the condition of the area ratio _S B / _{S A} of the coarse portion 111 and the smoothing unit 113 is as follows. That is, not only when the rough portion 111 is formed in the recess 101 forming the hairline and the smooth portion 113 is formed in the non-hairline portion 103 as shown in FIG. 2, but also in FIG. It has been confirmed that the same applies to the case where the smooth portion 113 is formed in the recess 101 constituting the hairline and the rough portion 111 is formed in the non-hairline portion 103 as shown in the above.
However, in FIG. 6, h1 is the average surface height of the smooth portion 113, and h2 is the average surface height of the rough portion 111.

[About surface roughness in rough areas]
In the oxide layer 14, the rough portion 111 is present in an appropriate ratio, so that the processing adhesion when the organic resin coating layer 15 is provided on the upper layer of the oxide layer 14 is ensured. Here, in order to ensure the processing adhesion by the rough portion 111, the rough portion 111 has an appropriately wide region having an appropriate surface roughness, so that the contact area with the organic resin coating layer 15 is increased. It is preferable to increase.

Therefore, in the oxide layer 14, when the rough portion 111 is measured using a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more, the surface is rough. is Ra _a is considered a region is 500nm ultra 5000nm or less, the total area of such regions, with respect to the area _{S a} of the coarse portion 111 is preferably made 85% or more.

By having the rough portion 111 _{having a region having a surface roughness Ra A of} more than 500 nm and 5000 nm or less, it is possible to more reliably realize a contact state with the organic resin coating layer 15, which can realize excellent processing adhesion. Can be done. Total area of such regions, with respect to the area S _A of the coarse portion 111, if less than 85%, the galvanized steel sheet 1 according to this embodiment, to realize excellent processability adhesion May be difficult. Therefore, the galvanized steel sheet 1 according to this embodiment, the ratio of the total area to the area S _A of the coarse portion 111 preferably be 85% or more.

Further, with respect to the area _{S A} of the coarse portion 111, the ratio of the total area of the region where the surface roughness Ra _A is equal to or less than 500nm ultra 5000nm is higher well, preferably 90% or more, more preferably 95% That is all. The upper limit of the ratio of the total area to the area S _A of the coarse portion 111 is not particularly specified, and may be 100%.

[About surface roughness in smooth parts]
Further, in the oxide layer 14, the smooth portion 113 is present in an appropriate ratio, so that the metallic feeling of the zinc-based plated steel sheet 1 according to the present embodiment is realized. Here, in order to realize the effect of improving the metallic feeling by the smooth portion 113, as illustrated in FIG. 4, the smooth portion 113 may have an appropriately wide region having an appropriate surface roughness. preferable.

Therefore, in the oxide layer 14, the surface of the smooth portion 113 is rough when measured using a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more. is Ra _B is considered an area is 5nm super 500nm or less, the total area of such regions, to the area _{S B} of the smoothing unit 113 is preferably made 65% or more.

When the smooth portion 113 has _{a region having a surface roughness Ra B of} more than 5 nm and 500 nm or less, excellent glossiness can be more reliably realized. Total area of such regions, to the area S _B of the smoothing section 113, if less than 65%, the galvanized steel sheet 1 according to this embodiment, it possible to realize a sense of good metallic It can be difficult. Therefore, the galvanized steel sheet 1 according to this embodiment, the ratio of the total area to the area S _B of the smooth portion 113 65% or more.

The ratio of the total area to the area S _B of the smoothing portion 113, the higher the better, is preferably 70% or more, more preferably 75% or more. The upper limit of the proportion of the total area to the area S _B of the smoothing part 113, not particularly specified, and may be 100%.

_{For the total area as described above, the surface roughness Ra B} of the smooth portion 113 or the surface roughness Ra B of the smooth portion 113 is obtained by using a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more. _{The surface roughness Ra A} of the rough portion 111 can be measured along the same direction as the hairline at 1 μm intervals, and can be obtained by the following equations (2) and (3). Here, if the measurement length of Ra is too short, the local surface roughness will be measured, so the measurement length is set to 50 μm or more. When the observation field of view of the laser microscope is less than 50 μm, Ra may be obtained by observing a plurality of fields of view and connecting the plurality of fields of view. The number of measurements is 20 or more.

Crude unit total area: _{S A} × (number / total number of measurements Ra _A is equal to or less than 500nm ultra 5000 nm) · · · Equation (2)
Smoothing unit total area: _{S B} × (number / total number of measurements Ra _B becomes 5nm ultra 500nm or less) Equation (3)

Here, "the rough portion 111 _{includes a region having a surface roughness Ra A} of more than 500 nm and 5000 nm or less" is defined as follows. Using a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more, the surface roughness Ra _A of the rough portion 111 is set at 1 μm intervals along the same direction as the hairline. Measure with a measurement length of 50 μm or more. Then, when the average surface roughness Ra _A measured 20 times or more is more than 500 nm and 5000 nm or less, it is defined as "the rough portion 111 _{includes a region where the surface roughness Ra A} is more than 500 nm and 5000 nm or less".
_{Similarly, when the average surface roughness Ra B} measured 20 times or more for the smooth portion 113 is more than 5 nm and 500 nm or less, “the smooth portion 113 has a region where the surface roughness Ra _B is more than 5 nm and 500 nm or less. Includes. "
In this specification, the surface roughness Ra _A and Ra _B mean the arithmetic mean roughness Ra defined in JIS B 0601 (2001).

[About hairline formation frequency]
Further, in the zinc-based plating layer 13 and the oxide layer 14, the recess 101 (that is, the hairline) including the rough portion 111 or the smooth portion 113 as described above has an arbitrary 1 cm width range along the hairline orthogonal direction. It is preferably present at a frequency of 3 lines / cm or more and 80 lines / cm or less. By setting the frequency of hairline formation in the direction orthogonal to the hairline within the range of 3 lines / cm to 80 lines / cm, more excellent design can be realized. If the frequency of hairline formation in the direction orthogonal to the hairline is less than 3 lines / cm, the density of the hairline becomes too low, and there is a high possibility that the hairline cannot be recognized. On the other hand, when the frequency of hairline formation in the direction orthogonal to the hairline exceeds 80 lines / cm, the density of the hairline becomes too high and the hairline is not beautiful, and the design of the hairline may be impaired. ..

The lower limit of the frequency of existence of the recess 101 (that is, the hairline) in an arbitrary 1 cm width range along the direction orthogonal to the hairline is more preferably 10 lines / cm, still more preferably 15 lines / cm. Further, the upper limit of the frequency of existence of the recesses 101 (that is, hairlines) in an arbitrary 1 cm width range along the direction orthogonal to the hairline is more preferably 70 lines / cm, and further preferably 65 lines / cm.

The frequency of existence of the recess 101 is arbitrary by observing the surface of the oxide layer 14 with a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more. The range of 1 mm width can be specified by counting the number of recesses 101. That is, the average frequency of the recesses 101 is obtained by measuring 20 or more points in an arbitrary 1 mm width range on the surface of the oxide layer 14 and dividing the total number of recesses 101 in each range by the number of measurement points. Can be done.

As described above, the surface shape of the oxide layer 14 has been described in detail with reference to FIGS. 2 to 6.

(About other configuration examples of galvanized steel sheets)
Here, in FIGS. 1A and 1B, the case where the recess 101 is provided only in the zinc-based plating layer 13 and the oxide layer 14 is shown. However, in the galvanized steel sheet 1 according to the present embodiment, as shown in FIGS. 7A and 7B, even if the surface of the steel sheet 11 is provided with a recess 105 forming a hairline extending in a predetermined direction. good. In this case, the zinc-based hot-dip plating fills the recesses forming the hairline with its own thickness. Therefore, the plating is zinc-based electroplating.

More specifically, as shown in FIGS. 7A and 7B, the recess 105 is provided on the surface of the steel sheet 11 at a position corresponding to the hairline (that is, the recess 101) in the zinc-based plating layer 13 and the oxide layer 14. You may.

Here, as shown in FIGS. 1A and 7A, the recess 101 is provided only in the zinc-based plating layer 13 and the oxide layer 14, and as shown in FIGS. 1B and 7B, the surface of the steel plate 11 is also provided. The timing of hairline processing differs from the case where the recess 105 is provided when the zinc-based plated steel sheet 1 is manufactured. The difference in the timing of such hairline processing will be described in detail below.

(About the blackness of the surface of galvanized steel sheet)
The blackness of the surface of the galvanized steel sheet 1 according to the present embodiment is preferably 40 or less, more preferably 35 or less in terms of ^{L * value.}
Here, ^{L *} value means the ^{L *} value in CIE1976L ^* a ^* b ^* color system. Then, the L ^* value can be measured with a reflection spectrophotometer.
The L ^* value is measured according to JIS Z8781-4 (2013). There are two types of L ^* value measuring devices: the SCI method, which includes specularly reflected light, and the SCE method, which does not include specularly reflected light. Both represent blackness, but in the present invention, the measurement was performed by the SCI method.

Whether or not the recess 105 exists at a position corresponding to the recess 101 formed on the surface of the oxide layer 14 on the surface of the steel sheet 11 can be confirmed by a known method. As such a confirmation method, for example, a method of observing the zinc-based plated steel sheet 1 from the cross-sectional direction, a photograph of the oxide layer 14 taken from the surface, and only the oxide layer 14 and the zinc-based plated layer 13 with hydrochloric acid to which an inhibitor is added. Examples thereof include a method of comparing the oxide layer 14 and the photograph taken from the surface after the removal.

(About the manufacturing method of galvanized steel sheet)
Subsequently, a method for manufacturing a zinc-based electroplated steel sheet (plated steel sheet having a zinc-based electroplated layer 13) according to the present embodiment as described above will be briefly described.

<Manufacturing method-Part 1>
Hereinafter, first, a method for manufacturing the zinc-based electroplated steel sheet 1 having the structures shown in FIGS. 1A and 1B will be briefly described.
In such a case, first, the steel sheet 11 whose surface roughness has been adjusted is degreased with an alkaline solution and pickled with an acid using hydrochloric acid, sulfuric acid or the like. Then, the zinc-based electroplating layer 13 is formed on the surface of the steel plate 11. Here, the surface roughness of the steel sheet 11 can be adjusted by using a known method. For example, the surface roughness of the steel sheet 11 is rolled by rolling the steel sheet 11 with a roll adjusted so that the surface roughness is within a desired range. A method such as a method of transferring roughness can be used.

As a method for forming the zinc-based electroplating layer 13, a known electroplating method can be used. As the electroplating bath, for example, a sulfuric acid bath, a chloride bath, a zincate bath, a cyanide bath, a pyrophosphate bath, a boric acid bath, a citric acid bath, other complex baths, and combinations thereof can be used. Further, in the electrozinc alloy plating bath, in addition to Zn ions, one or more single ions or complexes selected from Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W and Zr. By adding ions, an electrozinc alloy plating layer 13 containing a desired amount of Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W and Zr can be formed. Further, it is more preferable to add an additive to the plating bath in order to stabilize the ions in the plating bath and control the plating characteristics.

The composition, temperature, flow velocity, current density at the time of plating, energization pattern, etc. of the electroplating bath may be appropriately selected so as to have a desired plating composition, and are not particularly limited. Further, the thickness can be controlled by adjusting the current value and the time within the range of the current density having a desired composition.

A hairline is formed on the plated steel sheet provided with the zinc-based electroplating layer 13 obtained as described above. The method for imparting a hairline is not particularly limited, and various known methods can be used. Examples of such known methods include a method of polishing with a polishing belt, a method of polishing with an abrasive grain brush, a method of transferring with a textured roll, and a predetermined grinding apparatus, as in the case of imparting a hairline to a stainless steel material. The method of grinding with the above can be mentioned.

The depth and frequency of the hairline can be controlled to a desired state by adjusting the particle size of the polishing belt or the abrasive grain brush, the depth of the texture of the roll, the reducing force, the relative speed, and the number of times.

The surface of the zinc-based electroplating layer 13 on which the hairline is formed as described above has irregularities due to the crystal particles of the plating. Therefore, in the method for producing a zinc-based electroplated steel sheet according to the present embodiment, after the hairline is formed, the surface shape of the zinc-based electroplated layer 13 satisfies various conditions of the oxide layer 14 as described above. The surface of the zinc-based electroplating layer 13 is ground, polished, or rolled with a roll whose surface roughness is adjusted by a known method until the shape is obtained.

Next, the oxide layer 14 is formed on the surface of the zinc-based electroplating layer 13 to which the hairline is provided.

Here, in the hairline formation on the zinc-based electroplating layer 13, the portion where the unevenness of the crystal particles of the plating layer remains corresponds to the hairline portion in the above-mentioned grinding treatment, polishing treatment, or rolling treatment. In addition, the non-hairline portion 103 around the remaining portion is appropriately ground, polished, or rolled. As a result, as schematically shown in FIG. 2, the treated portion (non-hairline portion 103) becomes a smooth portion in which the unevenness of the crystal particles in the plating layer is suppressed. Then, when the oxide layer 14 is formed on the flat portion of the plating layer, it becomes the smooth portion 113.
On the other hand, the concave portion 101 that has not been treated and forms a hairline becomes a rough portion in which the unevenness of the crystal particles of the plating layer remains. Then, when the oxide layer 14 is formed on the rough portion of the plating layer, it becomes the rough portion 111.

On the contrary, in the above-mentioned grinding treatment, polishing treatment, or rolling treatment, when only the portion to be the hairline portion is selectively ground, polished, and rolled, it is schematically shown in FIG. The recess 101 forming the hairline becomes a smooth portion in which the unevenness of the crystal particles in the plating layer is suppressed. Then, when the oxide layer 14 is formed on the flat portion of the plating layer, it becomes the smooth portion 113.
On the other hand, the untreated non-hairline portion 103 becomes a rough portion of the plating layer. Then, when the oxide layer 14 is formed on the rough portion of the plating layer, it becomes the rough portion 111.

A case where such a form shown in FIG. 6 is formed by polishing with an abrasive grain brush will be described. Although the surface of the zinc-based electroplating layer 13 before the formation of the hairline is flat, it is covered with the unevenness of the crystal particles of the plating layer. In this state, by polishing the surface of the zinc-based electroplating layer 13 with an abrasive grain brush, the scraped portion becomes a hairline (recessed portion 101). Moreover, in this hairline, since the convex portion of the crystal particles of the plating is also scraped by polishing, the surface roughness becomes lower than the original state and becomes smooth. That is, the formation of the hairline and the adjustment of the surface roughness in the hairline are performed at the same time.
On the other hand, on the surface of the zinc-based electroplating layer 13, the flat portion (non-hairline portion 103) that was not scraped by the abrasive grain brush is in a state where the unevenness of the crystal particles of the plating layer remains as before.
As described above, as shown in FIG. 6, the non-hairline portion 103 in which the rough portion 111 of the oxide layer 14 formed in the rough portion of the plating layer is predominantly present to ensure work adhesion, and the plating layer The smooth portion 113 of the oxide layer 14 formed in the smooth portion is predominantly present, and the recess 101 having a high glossiness coexists.

As a method for forming the oxide layer 14, a known method can be used, and examples thereof include a method in which an acidic aqueous solution in which nitrate and phosphoric acid are mixed is brought into contact with the zinc-based electroplating layer. In this way, the oxide layer 14 is formed on the surface of the zinc-based electroplating layer 13. At this time, oxides having a small particle size are deposited on the surface of the smooth zinc-based electroplating layer 13, and oxides having a large particle size are deposited on the surface of the coarse zinc-based electroplating layer 13. Therefore, the oxide layer 14 can be provided with the above-mentioned suitable surface properties.

Next, the surface of the oxide layer 14 to which the hairline is provided is coated with the organic resin coating layer 15 as needed. Here, the paint used for forming the organic resin coating layer 15 follows the surface shape of the oxide layer 14 at the moment when it is applied to the oxide layer 14, and once reflects the surface shape of the oxide layer 14. It is preferable that the leveling of the resin is slow. That is, it is desirable that the paint has a low viscosity at a high shear rate and a high viscosity at a low shear rate. Specifically, when the shear rate is 0.1 [1 / sec], the viscosity is 10 [Pa · s] or more, and when the shear rate is 1000 [1 / sec], the viscosity is 0.01 [Pa · s] or less. It is desirable to have a shear viscosity.

In order to adjust the shear viscosity within the above range, for example, in the case of a paint using an aqueous emulsion resin, a hydrogen-bonding viscosity adjusting agent can be added to adjust the shear viscosity. Such hydrogen-bonding viscosity modifiers can increase the viscosity of the paint because they are restrained by hydrogen bonds at low shear rates, but the hydrogen bonds are broken at high shear rates, resulting in a decrease in viscosity. do. This makes it possible to adjust the shear viscosity according to the desired coating conditions.

The method for coating the organic resin coating layer 15 is not particularly limited, and a known method can be used. For example, it is possible to use a paint adjusted to the viscosity as described above, apply it by a spraying method, a roll coater method, a curtain coater method, a die coater method, or a dipping pulling method, and then air-dry or bake-dry it to form it. can. The drying temperature and drying time, and the baking temperature and baking time may be appropriately determined so that the organic resin coating layer 15 to be formed has desired performance. At this time, if the temperature rising rate is slow, the time from the softening point of the resin component to the completion of baking becomes long and the leveling progresses. Therefore, it is preferable that the temperature rising rate is high.

<Manufacturing method-Part 2>
Next, a method for manufacturing a zinc-based electroplated steel sheet having a structure as shown in FIGS. 7A and 7B (plated steel sheet having a zinc-based electroplating layer 13) will be briefly described.
In such a case, a steel sheet having been adjusted in surface roughness in the same manner as in the above "Manufacturing method-No. 1" is used. Then, the steel sheet 11 is obtained by forming a hairline on the steel sheet before plating. The method of imparting a hairline to the steel sheet is not particularly limited, but is a method of polishing with a polishing belt, a method of polishing with an abrasive grain brush, a method of transferring with a textured roll, and a method of grinding with a predetermined grinding device. It is preferable to use a method or the like. As a result, the recess 105 as shown in FIGS. 7A and 7B is formed on the surface of the steel plate 11.

Subsequently, the zinc-based electroplating layer 13 is formed on the steel plate 11 on which the hairline is formed. Since the method for forming the zinc-based electroplating layer 13 can be carried out in the same manner as in the above-mentioned "Manufacturing method-No. 1", detailed description thereof will be omitted below. By electroplating the steel sheet 11 on which the hairline is formed, the zinc-based electroplating layer 13 is formed while maintaining the surface shape of the steel sheet 11 on which the hairline is formed. That is, the zinc-based electroplating layer 13 having a hairline at a position and shape corresponding to the hairline of the steel plate 11 in a plan view is formed.

Crystal particles of the plating layer are present on the surface of the zinc-based electroplating layer 13 formed as described above, as in the above-mentioned "Manufacturing method-No. 1". That is, the surface of the zinc-based electroplating layer 13 at this point is in a state where both the recess 101 and the non-hairline portion 103 are covered with the unevenness of the crystal particles of the plating.
Therefore, in this production method, after the formation of the zinc-based electroplating layer 13, the surface shape of the zinc-based electroplating layer 13 is zinc-based by a known method until the surface shape satisfies various conditions as described above. The surface of the electroplating layer 13 is ground, polished, or rolled with a roll having an adjusted surface roughness. As a result, the rough portion and the smooth portion corresponding to the rough portion 111 and the smooth portion 113 of the oxide layer 14 are formed on the surface of the zinc-based electroplating layer 13 as in the above-mentioned "Manufacturing method-1".

More specifically, for example, when polishing with an abrasive grain brush, only the non-hairline portion 103 of the surface of the zinc-based electroplating layer 13 is polished. As a result, in the non-hairline portion 103 polished by the abrasive grain brush, the convex portion of the crystal particles is scraped, so that the surface roughness becomes lower than the original state and becomes smooth, and the smooth portion is predominantly present. Then, when the oxide layer 14 is formed on the smooth portion of the plating layer, it becomes the smooth portion 113.
On the other hand, the recess 101, which forms a recess that is difficult for the abrasive grain brush to reach, is a rough portion in a state in which the unevenness of the crystal particles of the plating layer remains, almost as before. Then, when the oxide layer 14 is formed on the rough portion of the plating layer, it becomes the rough portion 111.
As described above, the non-hairline portion 103 in which the rough portion 111 of the oxide layer 14 formed in the rough portion of the plating layer is predominantly present to ensure the processing adhesion, and the oxide layer formed in the smooth portion of the plating layer. The smooth portion 113 of 14 is predominantly present, and the recess 101 having a high glossiness coexists.

Subsequently, the surface of the oxide layer 14 to which the hairline is provided is coated with the organic resin coating layer 15 as needed. Since the formation of the organic resin coating layer 15 can be carried out in the same manner as in the above-mentioned "Manufacturing method-No. 1", detailed description thereof will be omitted below.

Subsequently, as shown in FIG. 7B, the surface of the zinc-based electroplating layer 13 to which the hairline is provided is coated with an organic resin, if necessary. Since the formation of the organic resin coating layer 15 can be carried out in the same manner as in the above-mentioned "Manufacturing method-No. 1", detailed description thereof will be omitted below.

The method for manufacturing the zinc-based electroplated steel sheet according to the present embodiment has been described above.
As for the zinc-based electroplated steel sheet 1, when the form shown in FIG. 1A and the form shown in FIG. 7A are compared, the form shown in FIG. 7A is smoother not only in the plane but also in the depth direction. Since the portion is formed and the hairline is deepened, a high glossiness (texture) can be easily obtained. For the same reason, when the form shown in FIG. 1B and the form shown in FIG. 7B are compared, the form shown in FIG. 7B is more likely to obtain a higher glossiness (texture).

(About the manufacturing method of galvanized steel sheet)
Subsequently, a method for producing a zinc-based hot-dip plated steel sheet (plated steel sheet having a zinc-based hot-dip plating layer 13) according to the present embodiment as described above will be briefly described.

<Manufacturing method-Part 3>
Hereinafter, first, a method for manufacturing the zinc-based hot-dip plated steel sheet 1 having the structures shown in FIGS. 1A and 1B will be briefly described.
In such a case, first, the steel sheet 11 whose surface roughness has been adjusted is annealed, immersed in hot-dip plating at a steel sheet temperature of 450 ° C., and pulled up. The amount of plating adhered is adjusted by wiping with nitrogen gas at the time of withdrawal. When the steel sheet 11 and the plating layer are alloyed, they are heated by induction heating (hereinafter, may be simply referred to as IH) so that the ultimate temperature becomes 500 ° C. after plating.

As a method for forming the zinc-based hot-dip plating layer 13, a known hot-dip plating method can be used. For example, as a type of hot-dip galvanizing bath, one having a total of elements other than Zn of less than 5% by mass can be used. For example, a plating bath containing Zn and 2% by mass of Al is used. Further, as the type of the zinc alloy hot-dip plating bath, those having a total alloy element content of 5% by mass or more can be used, for example, those containing 55% by mass of Al, 13% by mass of Al and 3% by mass. Those containing Mg and the like can be used.

The composition, temperature, gas wiping flow velocity, plating adhesion amount, and the like of the hot-dip plating bath may be appropriately selected so as to obtain a desired plating composition, and are not particularly limited.

The hairline according to the present embodiment is formed on the plated steel sheet 11 provided with the zinc-based hot-dip plating layer 13 obtained as described above. The method for imparting a hairline is not particularly limited, and various known methods can be used. Examples of such known methods include a method of polishing with a polishing belt, a method of polishing with an abrasive grain brush, a method of transferring with a textured roll, and a predetermined grinding apparatus, as in the case of imparting a hairline to a stainless steel material. The method of grinding with the above can be mentioned.

The depth and frequency of the hairline can be controlled to a desired state by adjusting the particle size of the polishing belt or the abrasive grain brush, the depth of the texture of the roll, the reducing force, the relative speed, and the number of times.

On the surface of the zinc-based hot-dip plating layer 13 on which the hairline is formed as described above, there is no unevenness due to the crystal particles of the plating as in the zinc-based electroplating layer 13 described above. Unevenness is formed on the surface of the zinc-based hot-dip plating layer 13. In the method for producing the zinc-based hot-dip plated steel sheet 1 according to the present embodiment, after the hairline is formed, the surface shape of the zinc-based hot-dip-plated layer 13 satisfies various conditions of the surface texture of the oxide layer 14 as described above. The surface of the zinc-based hot-dip plating layer 13 is ground, polished, or rolled with a roll having an adjusted surface roughness by a known method until the surface shape is obtained.

Next, the oxide layer 14 is formed on the surface of the zinc-based hot-dip plating layer 13 to which the hairline is provided.

Here, in the hairline formation on the zinc-based hot-dip plating layer 13, in the above-mentioned grinding treatment, polishing treatment, or rolling treatment, grinding is appropriately performed so that the unevenness formed on the surface of the plating layer corresponds to the hairline portion. , Polishing, or rolling. As a result, as schematically shown in FIG. 2, the untreated portion becomes a smooth portion in which the unevenness of the crystal particles of the plating is suppressed. Then, when the oxide layer 14 is formed on the flat portion of the plating layer, it becomes the smooth portion 113.
On the other hand, the treated concave portion 101 becomes a rough portion in which the unevenness of the crystal particles of the plating remains. Then, when the oxide layer 14 is formed on the rough portion of the plating layer, it becomes the rough portion 111.

On the contrary, in the above-mentioned grinding treatment, polishing treatment, or rolling treatment, when only the portion to be the hairline portion is selectively ground, polished, and rolled, it is schematically shown in FIG. The recess 101 forming the hairline becomes a smooth portion in which the unevenness of the crystal particles of the plating is suppressed. Then, when the oxide layer 14 is formed on the flat portion of the plating layer, it becomes the smooth portion 113.
On the other hand, the untreated non-hairline portion 103 becomes a rough portion. Then, when the oxide layer 14 is formed on the rough portion of the plating layer, it becomes the rough portion 111.

A case where such a form shown in FIG. 6 is formed by polishing with an abrasive grain brush will be described. The surface of the zinc-based hot-dip plating layer 13 before hairline formation is flat. It is covered with the unevenness of the crystal particles of the plating. In this state, by polishing the surface of the zinc-based hot-dip plating layer 13 with an abrasive grain brush, the scraped portion becomes a hairline (recessed portion 101). Moreover, in this hairline, since unevenness is formed in the plating by polishing, the surface roughness becomes higher than in the original state. That is, the formation of the hairline and the adjustment of the surface roughness in the hairline are performed at the same time. On the other hand, on the surface of the zinc-based hot-dip plating layer 13, the flat portion (non-hairline portion 103) that has not been scraped by the abrasive grain brush is in a smooth plating state as before. As described above, as shown in FIG. 6, the non-hairline portion 103 in which the rough portion 111 of the oxide layer 14 formed in the rough portion of the plating layer is predominantly present to ensure work adhesion, and the plating layer The smooth portion 113 of the oxide layer 14 formed on the flat portion is predominantly present, and the recess 101 having a high glossiness coexists.

As a method for forming the oxide layer 14, a known method can be used, and examples thereof include a method in which an acidic aqueous solution in which nitrate and phosphoric acid are mixed is brought into contact with the zinc-based electroplating layer. This oxide layer forms oxide particles according to the metal particle size on the surface of the zinc-based hot-dip plating layer that is the base. Therefore, oxides having a small particle size are deposited on the surface of the smooth zinc-based hot-dip plating layer, and oxides having a large particle size are deposited on the surface of the coarse zinc-based hot-dip plating layer. Therefore, the oxide layer 14 can be provided with the above-mentioned suitable surface properties.

Next, the surface of the oxide layer 14 to which the hairline is provided is coated with the organic resin coating layer 15 as needed. The paint used for forming the organic resin coating layer 15 is the same as the paint used for the above-mentioned galvanized steel sheet.

The method for coating the organic resin coating layer is not particularly limited, and a known method can be used. For example, it is possible to use a paint adjusted to the viscosity as described above, apply it by a spraying method, a roll coater method, a curtain coater method, a die coater method, or a dipping pulling method, and then air-dry or bake-dry it to form it. can. The drying temperature and drying time, and the baking temperature and baking time may be appropriately determined so that the organic resin coating layer 15 to be formed has desired performance. At this time, if the temperature rising rate is slow, the time from the softening point of the resin component to the completion of baking becomes long and the leveling progresses. Therefore, it is preferable that the temperature rising rate is high.

(Modification example)
In the above embodiment, the case where the surface of the zinc-based plating layer provided with the hairline is covered with the oxide layer has been described. Hereinafter, the case of imparting a hairline to the surface of the oxide layer will be described with reference to FIGS. 10 to 12. In the modified example, a part of the oxide layer is removed and the bottom of the recess reaches the zinc-based plating layer. Therefore, the contrast between the metallic color of the zinc-based plating layer and the black color of the oxide layer causes the average of the recesses. Even if the depth is very shallow, the visibility of the hairline appearance is excellent.

<1. Overall composition of galvanized steel sheet>
First, the overall configuration of the galvanized steel sheet 1'according to the modified example of the present embodiment will be described with reference to FIGS. 10 and 11. The galvanized steel sheet 1'includes a steel sheet 11', a zinc-based plated layer 13', and an oxide layer 14'. On the surface of the oxide layer 14', a linearly formed recess 101'and a flat portion 103' that is a region other than the recess 101'are formed. The recess 101'corresponds to the hairline portion and the flat portion 103'corresponds to the non-hairline portion. In order to further improve the characteristics (particularly corrosion resistance, etc.) of the galvanized steel sheet 1', the galvanized steel sheet 1'covers the recess 101'and the flat portion 103' and has a translucent organic resin coating layer 15'. It is preferable to further provide'. The zinc-based plating layer 13', the oxide layer 14', and the organic resin coating layer 15'may be provided on both sides of the steel sheet 11', or may be provided on only one side. Hereinafter, each component will be described.

<2. Steel plate ＞
The steel sheet 11'which is the base material of the galvanized steel sheet 1'is not particularly limited, and is known depending on the mechanical strength (for example, tensile strength, etc.) required for the galvanized steel sheet 1'. Various steel materials (mild steel, ordinary steel, high-strength steel, etc.) can be appropriately used as the steel sheet 11'.

<3. Zinc-based plating layer>
The zinc-based plating layer 13'is formed on at least one surface of the steel plate 11'. Zinc-based plating was selected as the metal type for plating in the modified example of the present embodiment because zinc-based plating has excellent sacrificial anticorrosion properties.

The zinc-based plating layer 13'is, for example, a zinc-based electroplating layer or a zinc-based hot-dip plating layer. The zinc-based electroplating layer is formed on the surface of the steel sheet 11'by electrogalvanizing the steel sheet 11'. The zinc-based hot-dip galvanized layer is formed on the surface of the steel sheet 11'by hot-dip galvanizing the steel sheet 11'. The zinc-based plating layer 13'may be formed by another plating method, for example, a thermal spraying method, a vapor deposition plating method, or the like. However, in the thermal spraying method, since voids are formed inside the zinc-based plating layer 13', there is a possibility that the uniformity of appearance cannot be ensured. Further, in the vapor deposition method, the productivity is poor because the film formation rate is slow. Therefore, the zinc-based plating layer 13'preferably is a zinc-based electroplating layer or a zinc-based hot-dip plating layer. Further, the zinc-based plating layer 13'is more preferably a zinc-based electroplating layer. By forming the zinc-based plating layer 13'by electrogalvanization, the zinc-based plating layer 13'can be easily thinned. Therefore, the raw material cost and the like can be reduced. Although the details will be described later, even if the zinc-based plating layer 13'is a thin film, the characteristics (corrosion resistance, hairline appearance, etc.) of the zinc-based plated steel sheet 1'can be sufficiently enhanced.

(3-1. Composition of zinc-based electroplating layer)
The zinc-based electroplating layer is classified into an electrogalvanizing layer and an electrogalvanizing alloy plating layer. The electrogalvanized layer is composed of Zn and impurities. The electrozinc alloy plating layer contains additive elements described later, and the balance is composed of Zn and impurities. In any of the plating layers, the Zn content is 35% by mass or more, more preferably 70% by mass or more, and more preferably 80% by mass or more with respect to the total mass of the zinc-based plating layer 13'. .. The upper limit of the Zn content is 100% by mass at the maximum, but considering that impurities are almost certainly present, it is less than 100% by mass.

The electrozinc alloy plating layer is one or more selected from the group consisting of Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, and Zr as the above-mentioned additive elements. It is preferable that the additive elements are contained in an amount of 5 to 20% by mass in total of these additive elements with respect to the total mass of the zinc-based plating layer 13'. In particular, in the electrozinc alloy plating layer, as the above-mentioned additive element, any one or more additive elements selected from the group consisting of Fe, Ni, and Co are added to the total mass of the zinc-based plating layer 13'. It is more preferable that the total content of these additive elements is 5 to 20% by mass. In this case, the corrosion resistance (white rust resistance, barrier property, etc.) of the galvanized steel sheet 1'is further improved.

The impurities contained in the electrogalvanized layer and the electrogalvanized alloy plating layer are not intentionally added as components of the zinc-based electroplating layer, but are mixed in the raw material or mixed in the manufacturing process. , So-called impurities. Such impurities include Al, Mg, Si, Ti, B, S, N, C, Nb, Pb, Cd, Ca, Pb, Y, La, Ce, Sr, Sb, O, F, Cl, Zr. , Ag, W, H and the like. Other types of impurities include Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, and Zr. Elements other than the above-mentioned additive elements may be added to the electrogalvanized layer and the electrogalvanized alloy plated layer as long as the effects of the modifications of the present embodiment are not impaired. Such additive elements are also classified as impurities. The total mass% of the elements serving as impurities is preferably less than 1% by mass at the maximum with respect to the total mass of the zinc-based electroplating layer. In this case, these elements have almost no effect on the zinc-based plating layer 13'. The intentionally added Fe, Ni, and Co and the Fe, Ni, and Co mixed as impurities can be distinguished from each other by the concentration in the zinc-based plating layer 13'. That is, for example, since the lower limit of the total content of Fe, Ni, and Co when added intentionally is 5% by mass, if the total content of Fe, Ni, and Co is less than 5% by mass, Fe. , Ni, Co can be discriminated as impurities.

The composition of the zinc-based plating layer 13'(that is, the zinc-based electroplating layer described above and the zinc-based hot-dip plating layer described later) is, for example, the same method as the method for analyzing the composition of the zinc-based electroplating layer described above. It is possible to analyze. As another method, the plated steel plate is immersed in 10% by mass hydrochloric acid containing an inhibitor (for example, NO.700AS manufactured by Asahi Chemical Co., Ltd.) to dissolve and peel off, and the dissolved solution is inductively coupled plasma emission spectrometer (Inductively Coupled Plasma). : ICP) can also be used for analysis.

(3-2. Composition of zinc-based hot-dip plating layer)
The zinc-based hot-dip galvanizing layer is classified into a hot-dip galvanizing layer and a hot-dip zinc alloy plating layer. The hot-dip galvanized layer is composed of Zn and impurities. The molten zinc alloy plating layer contains additive elements described later, and the balance is composed of Zn and impurities. In any of the plating layers, the Zn content is 35% by mass or more, more preferably 70% by mass or more, and more preferably 80% by mass or more with respect to the total mass of the zinc-based plating layer 13'. .. The upper limit of the Zn content is 100% by mass at the maximum, but considering that impurities are almost certainly present, it is less than 100% by mass. In addition, any one or more additive elements selected from the group consisting of Al, Sb, and Pb may be added to the hot-dip galvanized layer. In this case, the total amount of these elements added is preferably 1% by mass or more and less than 5% by mass.

In the hot-dip zinc alloy plating layer, as the above-mentioned additive elements, any one or more additive elements selected from the group consisting of Fe, Al, Mg, and Si are added to the total mass of the zinc-based plating layer 13. It is preferable that the total amount of the added elements of the above is 1 to 60% by mass. In particular, in the molten zinc alloy plating layer, as the above-mentioned additive elements, any one or more additive elements selected from the group consisting of Al and Mg are added to the total mass of the zinc-based plating layer 13'. It is more preferable that the total amount of the added elements is 1 to 60% by mass. In this case, the corrosion resistance (white rust resistance, barrier property, etc.) of the galvanized steel sheet 1'is further improved.

The impurities contained in the hot-dip galvanizing layer and the hot-dip zinc alloy plating layer are not intentionally added as components of the zinc-based hot-dip galvanizing layer, but are mixed in the raw material or mixed in the manufacturing process. , So-called impurities. Examples of such impurities include Al, Mg, Si, Ni, Ti, Pb, Sb and the like. Elements other than the above-mentioned additive elements may be added to the hot-dip galvanizing layer and the hot-dip galvanizing layer as long as the effects of the modifications of the present embodiment are not impaired. Such additive elements are also classified as impurities. The total mass% of the elements serving as impurities is preferably less than 1% by mass at the maximum with respect to the total mass of the zinc-based hot-dip plating layer. In this case, these elements have almost no effect on the zinc-based plating layer 13'. The intentionally added additive element and the impurity can be distinguished from each other by the concentration in the zinc-based plating layer 13'. That is, for example, since the lower limit of the total content of the added elements intentionally added is 1% by mass, if the total content of each element is less than 1% by mass, these elements can be discriminated as impurities.

(3-3. Average amount of zinc-based plating layer adhered)
The average adhesion amount of the zinc-based plating layer 13'is preferably 5 to ^{40 g / m 2.} The average amount of adhesion is a value obtained by dividing the total mass of the zinc-based plating layer 13'attached to the steel sheet 11'by the area of the surface to which the zinc-based plating layer 13'attached. The amount of plating adhesion can be measured, for example, by immersing the plated steel sheet in 10% by mass hydrochloric acid containing an inhibitor (NO.700AS manufactured by Asahi Chemical Co., Ltd.) to dissolve and peel it off, and measuring the mass change of the steel sheet before and after immersion. When the average adhesion amount of the zinc-based plating layer 13'is ^{less than 5 g / m 2} , the base iron (that is, the steel plate 11') is exposed when the recess 101'(that is, the hairline) is formed in the oxide layer 14. there is a possibility. Therefore, the appearance of the hairline and the corrosion resistance may be deteriorated. On the other hand, when the average adhesion amount of the zinc-based plating layer 13'exceeds 40 g / m ² , the manufacturing cost may increase. The lower limit of the average adhesion amount of the zinc-based plating layer 13'is more preferably 7 g / m ² or more, and more preferably 10 g / m ² or more. The upper limit of the average adhesion amount of the zinc-based plating layer 13'is more preferably 35 g / m ² or less, and more preferably 30 g / m ² or less.

<4. Oxide layer>
The oxide layer 14'is formed on the surface of the zinc-based plating layer 13'. The oxide layer 14'is formed on the surface of the zinc-based plating layer 13'by oxidizing the zinc-based plating layer 13'. The specific contents of the oxidation treatment will be described later.

The zinc-based plated steel sheet 1'has a high degree of blackness by having such an oxide layer 14'. Although the details will be described later, for example, the blackness of the surface of the galvanized steel sheet ^{1'can be} set to 50 or less in L * value by the oxide layer 14'. L ^* is preferably 40 or less, more preferably 35 or less. When the organic resin coating layer 15'containing the black pigment is formed on the surface of the oxide layer 14'(the surface of the recess 101'and the flat portion 103' described later), the L ^* value is reduced to 40 or less by the synergistic effect of these. Can be. Here, the ^{L *} value means the ^{L *} value in CIE1976L ^* a ^* b ^* color system, measured in reflection spectrodensitometer.

The oxide layer 14'contains, for example, at least one of the group consisting of zinc hydroxide and zinc oxide. As a result, a high degree of blackness is realized. Specific examples of zinc hydroxide and zinc oxide include ZnO, ZnO _1-x , Zn (OH) _{2, and the} like. The oxide layer 14 preferably further contains any one or more additive elements selected from the group consisting of Fe, Ni, and Co as the second component. These elements are derived from the zinc-based plating layer 13', especially the electrozinc alloy plating layer. When the oxide layer 14'contains these second components, the blackness of the galvanized steel sheet 1 becomes higher.

The average thickness of the oxide layer 14'is preferably 0.05 μm or more and less than 3.0 μm. If the average thickness of the oxide layer 14'is less than 0.05 μm, sufficient blackness may not be obtained. When the average thickness of the oxide layer 14'is 3.0 μm or more, cracks may occur in the oxide layer 14'during the processing of the galvanized steel sheet 1'. If such a crack is formed in the oxide layer 14', the processing adhesion, particularly the adhesion to the organic resin coating layer 15, may be deteriorated. The lower limit of the average thickness of the oxide layer 14'is more preferably 0.07 μm, and more preferably 1.0 μm. The upper limit of the average thickness of the oxide layer 14'is preferably 2.7 μm, more preferably 2.5 μm.

The average thickness of the oxide layer 14'is specified by, for example, the following method. That is, any region of the cross section of the galvanized steel sheet 1'in the plate thickness direction is set as the cross section observation region. Here, the cross-section observation region includes at least a region from the surface of the oxide layer 14'to a depth of 0.3 μm or more. Next, this cross-sectional observation region is observed with a transmission electron microscope (TEM-EDS) equipped with an EDS (energy dispersive X-ray analyzer). In this way, the element distribution in the cross-section observation region is specified. Then, the oxygen concentration (the oxygen concentration here is the oxygen concentration in each micro region in the cross-sectional observation region, that is, the mass% of the oxygen in the micro region with respect to the total mass of all the elements existing in the micro region). A region in which is 20% by mass or more is specified as the oxide layer 14'. Here, the composition of the oxide layer 14'can also be specified by specifying the element distribution in the oxide layer 14'by TEM-EDS. Further, the thickness of the oxide layer 14'may be measured at a plurality of places, and the arithmetic mean value thereof may be used as the average thickness of the oxide layer 14'.

<5. Surface structure of oxide layer>
On the surface of the oxide layer 14', a linearly formed recess 101'and a flat portion 103' that is a region other than the recess 101'are formed. The recess 101'is a so-called hairline.

The recess 101'is formed by polishing the surface of the oxide layer 14', that is, removing a part of the oxide layer 14'. The bottom portion 101a'of the recess 101'(the portion existing at the deepest position of each recess 101) reaches the zinc-based plating layer 13'under the oxide layer 14'. As described above, since the zinc-based plating layer 13'is exposed in the recess 101', the appearance of the hairline is improved. That is, the appearance (visibility) of the hairline is improved by the contrast between the metal color of the zinc-based plating layer 13'in the recess 101'and the black color of the oxide layer 14'.

The average depth of the recess 101'is 0.1 μm or more and less than 3.0 μm. As described above, in the modified example of the present embodiment, the average depth of the recess 101'is very shallow. However, as shown in Examples described later, a good hairline appearance is obtained. Further, since the average depth of the recess 101'is very shallow, the recess 101'can be easily formed and the generation of shavings can be suppressed. When the average depth of the recess 101 is less than 0.1 μm, the bottom of the recess 101'does not reach the zinc-based plating layer 13', and a good hairline appearance cannot be obtained. In addition, the metallic feeling is also reduced. When the average depth of the recess 101'is 3.0 μm or more, not only is it time-consuming to form the recess 101', but also a large amount of shavings are generated. In addition, corrosion resistance and processing adhesion are reduced. The average depth of the recess 101'is preferably 0.1 μm or more and less than 2.0 μm.

The average depth of the recess 101'is measured by, for example, the following method. That is, a laser microscope having a display resolution in the depth direction of 1 nm or more and a display resolution in the direction perpendicular to the depth direction (plane direction) of 1 nm or more is prepared. Then, an arbitrary 1 cm × 1 cm region on the surface of the oxide layer 14'is set as a plan view observation region. This plan view observation region is scanned with a laser microscope along the direction orthogonal to the hairline. The scanning interval is, for example, 100 μm. As a result, a plurality of line profiles of the surface shape are acquired. An example of the line profile is shown in FIG. The horizontal axis of FIG. 12 indicates the measurement length (μm), and the vertical axis indicates the surface height (μm) from a preset reference position. Then, the line profile, H ₁ to the highest point within the range of the observation width 1cm along the hairline orthogonal _directions, if the lowest point was H ₀ (these highest point H _1, the lowest point H ₀ is hairline perpendicular direction _{A point existing at a height of H 0} + 2/3 × (H ₁ −H ₀ ) and on a line intersecting the hairline at a right angle (specified by a line profile along the hairline) is a recess 101'and a flat portion 103'. The boundary point with. Then, the distance in the depth direction (that is, the bottom 101a'of the recess 101') from the straight line connecting the adjacent boundary points in the same recess to the point at the deepest position between the boundary points (the boundary points from the bottom 101a'). The length of the straight line in the depth direction drawn along the straight line connecting the two) is defined as the depth of the recess 101'. Then, the average depth of the recesses is calculated by arithmetically averaging the depths of all the recesses 101'measured in each line profile. The position of the recess 101'in the plan view observation region is also specified by this method. Further, in the modified example, the method of defining the boundary point is different from that of the present embodiment due to the difference in the manufacturing method. In the modified example, the boundary point between the recess 101'and the flat portion 103'is located closer to the bottom as compared with the embodiment.
Since the zinc-based plating layer 13'is exposed in the recess 101', the appearance of the hairline is good. In order to realize excellent visibility, it is preferable that the zinc-based plating layer is scraped to a certain depth. That is, [(H ₁ −H ₀ ) − (average thickness of the oxide layer)] is preferably 0.1 μm or more, and more preferably 0.3 μm or more.

The average length of the recess 101'along the length direction is preferably 1 cm or more. Further, the recesses 101'preferably exist in an arbitrary 1 cm width range along the direction orthogonal to the length direction of the recesses 101' at a frequency of 3 to 80 lines / cm on average. Hereinafter, the number of recesses 101'existing within an arbitrary 1 cm width range is also referred to as "the number of recesses 101'per unit width". When these requirements are satisfied, the hairline appearance, metallic feeling, and processing adhesion are improved. Whether or not the recess 101'satisfies these requirements may be determined based on the above-mentioned observation result in the plan view observation region. That is, the length of each recess 101'existing in the plan view observation region along the length direction may be measured, and it may be determined whether or not the arithmetic mean value thereof is 1 cm. In addition, a number of 1 cm wide regions are arbitrarily selected in the plan view observation region, and the number of recesses 101'existing in each selected region is measured. Then, the number of recesses 101'existing in each region is arithmetically averaged. Then, it may be determined whether or not the arithmetic mean value is 3 to 80 lines / cm.

Further, the ratio (area ratio ratio) of the area ratio AR1 of the oxide layer 14'existing in the recess 101'in the plan view and the area ratio AR2 of the oxide layer 14'existing in the flat portion 103' in the plan view. ) AR1 / AR2 is 0 or more and 0.5 or less. When this condition is satisfied, the blackness, the appearance of the hairline and the metallic feeling are improved.

Here, the area ratio AR1 is a value obtained by dividing the area of the oxide layer 14'existing in the recess 101'in the plan view by the area of the recess 101'in the plan view. Since the recess 101'is formed by polishing the oxide layer 14', ideally, the oxide layer 14'does not exist on the surface of the recess 101'. Therefore, the area ratio AR1 becomes 0, and the area ratio AR1 / AR2 becomes 0. However, the oxide layer 14'in the recess 101' may not be sufficiently removed due to wear of the abrasive material or the like. In this case, since the oxide layer 14'slightly remains in the recess 101', AR1 becomes larger than 0. However, if AR1 becomes excessively large, most of the surface of the recess 101'will be covered with the oxide layer 14', and the hairline appearance and metallic feeling will be impaired.

On the other hand, the area ratio AR2 is a value obtained by dividing the area of the oxide layer 14'existing in the flat portion 103'in the plan view by the area of the flat portion 103'in the plan view. Since the flat portion 103'is a portion where the oxide layer 14 remains, the AR2 is ideally 100. However, there is a possibility that the flat portion 103'is also slightly polished by the abrasive in the process of forming the recess 101'. As a result, AR2 can be less than 100. When AR2 becomes excessively small, the oxide layer 14'existing in the flat portion 103'is reduced, and the blackness is lowered. Therefore, the present inventor paid attention to the balance between the two, and found that when the area ratio ratio AR1 / AR2 was 0 to 0.5, the blackness, the hairline appearance, and the metallic feeling were good.

Here, the area ratio AR1, the area ratio AR2, and the area ratio ratio AR1 / AR2 are measured by the following methods. That is, the above-mentioned plan view observation region is observed with a field emission electron probe microanalyzer (FE-EPMA). In this way, the element distribution in the plan view observation region is specified. Then, in each region in the recess 101', the oxygen concentration (the oxygen concentration here is the oxygen concentration in each minute region in the plan view observation region, that is, the total mass of all the elements existing in the minute region). (% By mass of oxygen in the microregion) is measured. FE-EPMA detects elemental information at a depth of about 1 μm. Therefore, when the average thickness of the oxide layer exceeds 1 μm, the region where the oxygen detected by FE-EPMA is 20% by mass or more is specified as the oxide layer 14. When the average thickness of the oxide layer is 1 μm or less, the region where the obtained oxygen concentration satisfies the following relationship is specified as the oxide layer 14'.
Detected oxygen concentration> Oxide layer average thickness [μm] / 1 [μm] x 20% by mass
The region other than the oxide layer 14'is the zinc-based plating layer 13'exposed in the recess 101'. As a result, the area of the oxide layer 14'existing in the recess 101'in the plan view observation region in the plan view can be obtained, and this is divided by the area of the recess 101'in the plan view observation region in the plan view. By doing so, the area ratio AR1 is obtained.

Further, among the regions in the flat portion 103', the region to be the oxide layer 14'is specified by the same method as described above. The region other than the oxide layer 14'is the zinc-based plating layer 13'exposed in the flat portion 103'. As a result, the area of the oxide layer 14'existing in the flat portion 103'in the plan view observation region in the plan view can be obtained. The area ratio AR2 is obtained by dividing. Then, the area ratio AR1 / AR2 is obtained by dividing the area ratio AR1 by the area ratio AR2.

Further, it is preferable that the recess 101'includes a region having a surface roughness RaA' of more than 5 nm and 500 nm or less, and the flat portion 103' includes a region having a surface roughness RaB' of more than 500 nm and 5000 nm or less. Thereby, the appearance of the hairline and the metallic feeling can be further enhanced. The surface roughness RaA'and RaB'are both centerline average roughness (arithmetic mean roughness). That is, the surface roughness RaA'and RaB'mean the arithmetic mean roughness Ra defined in JIS B 0601 (2001), and the measuring method thereof is the surface roughness Ra _A of the rough portion 111 or the surface of the smooth portion 113. It is the same as the roughness Ra _B.

On the surface of the oxide layer 14'before polishing, that is, before forming the recess 101', many irregularities derived from the irregularities of the zinc-based plating layer 13'under the lower layer are formed. That is, a large number of crystal particles having a relatively large particle size are present on the surface of the zinc-based plating layer 13', and relatively coarse irregularities are formed by these crystal particles. Then, on the surface of the oxide layer 14', relatively rough irregularities derived from the irregularities of the zinc-based plating layer 13'are formed. The surface roughness Ra'of the oxide layer 14'is often more than 500 nm and 5000 nm or less due to such unevenness.

By polishing the surface of such an oxide layer 14', a recess 101'is formed on the surface of the oxide layer 14'. Therefore, since the surface of the recess 101'is polished, the surface roughness RaA' becomes small. Then, when the surface roughness RaA'is more than 5 nm and 500 nm or less, the metallic feeling becomes particularly good. Therefore, the recess 101'preferably includes a region having a surface roughness RaA' of more than 5 nm and 500 nm or less.

On the other hand, since the flat portion 103'is not polished as much as the concave portion 101', the above-mentioned rough unevenness often remains almost as it is. Due to the anchor effect due to such rough irregularities, the adhesion between the oxide layer 14'and the organic resin coating layer 15', that is, the processing adhesion is improved. Therefore, it is preferable that the flat portion 103'includes a region having a surface roughness RaB' of more than 500 nm and 5000 nm or less. The surface roughness RaA'and RaB' are measured by the above-mentioned line profile of the surface shape. The surface roughness RaA'and RaB'measured by a plurality of line profiles may be arithmetically averaged, or the surface roughness RaA'and RaB' measured from any of the line profiles may be selected as representative values. good.

On the surface of the oxide layer 14', the above-mentioned rough irregularities are formed by densely distributing oxide particles having a relatively large particle size. Therefore, the average particle size and density of such oxide particles will be briefly described. The average particle size of the oxide particles is measured by, for example, the following method. First, the surface of the oxide layer 14'is observed by SEM. The visual field magnification at that time may be in the range of 1000 to 10000 times. However, if the oxide particles cannot be confirmed even at the maximum magnification of 10000 times, the number of oxide particles is counted as zero in the observation field of view. The observation field of view is changed until at least 10 oxide particles can be observed in the observation field of view.

When 10 or more oxide particles can be confirmed in the observation field of view, the flat area S (μm ² ) per oxide particle is obtained based on the contour of the oxide particles. Then, the representative diameter D (μm) of the oxide particles is obtained based on the flat area S and the following formula (1). As is clear from the formula (1), the representative diameter D is the equivalent circle diameter of the oxide particles. Then, 10 oxide particles in the observation field of view are arbitrarily selected, and the average value of the representative diameters D of the 10 oxide particles is taken as the average particle size.
D = 2 × (S / π) ^0.5 ... Equation (1)

The density of oxide particles can be determined by, for example, the following method. First, the surface of the oxide layer 14'is observed by SEM as described above. Then, the number of oxide particles whose average particle size is equal to or larger than the particle size threshold is counted within the range of 100 μm × 100 μm. As a result, the density of oxide particles is determined. The particle size threshold differs depending on the plating type and alloy of the lower zinc-based plating layer 13'. For example, when the lower zinc-based plating layer 13'is a Zn—Ni electrozinc alloy plating layer, the particle size threshold is 0.1 to 3.0 μm. When the zinc-based plating layer 13'is a Zn-Fe electrozinc alloy plating layer, the particle size threshold is 0.3 to 3.6 μm. When the zinc-based plating layer 13'is a Zn-Co electrozinc alloy plating layer, the particle size threshold is 0.4 to 9.6 μm. If the oxide particles cannot be confirmed even when the SEM magnification is set to the maximum magnification (10000 times), the number is counted as zero. In this case, the observation field of view is changed until the oxide particles are observed.

When the zinc-based plating layer 13'is a Zn-Fe electrozinc alloy plating layer, the average particle size of the oxide particles is 0.5 to 2.7 μm in the region where the surface roughness RaB' is more than 500 nm and 5000 nm or less. The value is within the range, and the density is often within the range of ^{2 × 10 10 to} 5 × 10 ¹⁴ pieces / m ^2.

When the zinc-based plating layer 13'is a Zn-Co electrozinc alloy plating layer, the average particle size of the oxide particles is 0.6 to 7. In the region where the surface roughness RaB' is more than 500 nm and 5000 nm or less. The value is in the range of 2 μm, and the density is often in the range of ^{0.5 × 10 10 to} 3.6 × 10 ¹⁴ pieces / m ^2.

When the zinc-based plating layer 13'is a Zn—Ni electrozinc alloy plating layer, the average particle size of the oxide particles is 0.3 to 2. In the region where the surface roughness RaB'is more than 500 nm and 5000 nm or less. It is in the range of 4 μm, and the density is often in the range of ^{5 × 10 10 to} 8.4 × 10 ¹⁴ pieces / m ^2.

Summarizing the above, when the zinc-based plating layer 13'is a zinc-based electroplating layer and contains any one or more elements selected from the group consisting of Fe, Ni, and Co as additive elements, the surface roughness RaB In the region where'is more than 500 nm and 5000 nm or less, the average particle size of the oxide particles is 0.3 μm or more, and the density ^{is often 10 10} particles / m ² or more. Of course, the average particle size and density of the oxide particles are not limited to the above-mentioned values. When the flat portion 103'includes a region having a surface roughness RaB' of more than 500 nm and 5000 nm or less, good work adhesion is good even if the average particle size and density of the oxide particles are outside the above ranges. Is obtained.

As described above, according to the galvanized steel sheet 1'according to the modified example of the present embodiment, good blackness, hairline appearance, and metallic feeling are obtained even when an inexpensive galvanized steel sheet is used. Can be realized. Further, since the average depth of the recess 101'is as shallow as 0.1 μm or more and less than 3.0 μm, the recess 101'can be easily formed and the generation of shavings can be suppressed. Even if the average depth of the recesses is very shallow, the appearance of the hairline is excellent in visibility. In the modified example, the bottom of the recesses reaches the zinc-based plating layer, and the metallic color and oxide of the zinc-based plating layer. This is due to the large contrast with the black color of the layer.

<6. Organic resin coating layer>
As shown in FIG. 11, the galvanized steel sheet 1'preferably further has an organic resin coating layer 15'that covers the recess 101'and the flat portion 103'. The organic resin coating layer 15'has translucency (transparency). Here, the fact that the organic resin coating layer 15'has translucency (transparency) means that the recess 101'and the flat portion 103' can be visually observed through the organic resin coating layer 15'. ..

The resin used for forming the organic resin coating layer 15'preferably having sufficient transparency, chemical resistance, corrosion resistance, processability, scratch resistance and the like. Examples of such resins include polyester resins, epoxy resins, urethane resins, polyester resins, phenol resins, polyether sulfone resins, melamine alkyd resins, acrylic resins, polyamide resins, and polyimides. Examples thereof include based resins, silicone resins, polyvinyl acetate resins, polyolefin resins, polystyrene resins, vinyl chloride resins, vinyl acetate resins and the like.

Various additives may be added to the organic resin coating layer 15'as long as the effects of the modifications of the present embodiment are not impaired. With these additives, it is possible to impart corrosion resistance, slidability, scratch resistance, conductivity, color tone, etc. to the galvanized steel sheet 1'. For example, when it is desired to improve the corrosion resistance of the galvanized steel sheet 1', a rust preventive or an inhibitor may be added to the organic resin coating layer 15'. These rust preventives or inhibitors preferably contain any one or more elements selected from Si, P, and Zr as their components. In this case, the corrosion resistance of the galvanized steel sheet 1 is further improved. If it is desired to impart slidability or scratch resistance to the galvanized steel sheet 1', wax, beads or the like may be added to the organic resin coating layer 15'. When it is desired to improve the conductivity of the galvanized steel sheet 1, a conductive agent or the like may be added to the organic resin coating layer 15'. When it is desired to adjust the color tone of the galvanized steel sheet 1', a known colorant such as a pigment or a dye may be added to the organic resin coating layer 15'. Here, by adding a black pigment to the organic resin coating layer 15', the blackness of the galvanized steel sheet 1 can be further enhanced. Of course, it is preferable to add a colorant such as a black pigment to the organic resin coating layer 15'to the extent that the hairline is not concealed. Specific examples of the colorant include Bengara, aluminum, mica, carbon black, titanium oxide, cobalt blue and the like. The content of the colorant is preferably 1 to 10% by mass, more preferably 2 to 5% by mass, based on the total mass of the organic resin coating layer 15'.

The organic resin coating layer 15'may have a multilayer structure. In this case, among the above-mentioned additives, it is particularly preferable that the colorant is added to any one or more layers other than the bottom layer (the layer covering the recess 101'and the flat portion 103'). By adding the colorant to a layer other than the bottom layer, the appearance of the hairline can be improved. In this case, the addition amount is preferably mass% as described above with respect to the total mass of the layer to be added.
In the modified example, the contrast between the metallic color of the zinc-based plating layer and the black color of the oxide layer enhances the visibility of the appearance of the hairline. In addition, the bottom layer coating film has a relatively thick coating film at the recesses forming the hairline. Therefore, when the colorant is added to the lowermost layer of the organic resin coating layer 15', the hairline may be hidden by the black coating film.

The average thickness of the organic resin coating layer 15'is preferably 10 μm or less. When the organic resin coating layer 15'has a multi-layer structure, the average thickness of the entire layer including all the layers is preferably 10 μm or less. When the average thickness of the organic resin coating layer 15'exceeds 10 μm, the distance through which light passes through the organic resin coating layer 15'is long, so that the glossiness may decrease. Further, there is a possibility that a gap may occur between the texture of the surface of the oxide layer 14'and the texture of the surface of the organic resin coating layer 15'. Therefore, the average thickness of the organic resin coating layer 15'is preferably 10 μm or less. The average thickness of the organic resin coating layer 15'is more preferably 8 μm or less.

On the other hand, the lower limit of the average thickness of the organic resin coating layer 15'is more preferably 1.0 μm. If the average thickness of the organic resin coating layer 15'is less than 1.0 μm, the function of the organic resin coating layer 15'may not be fully exhibited. Here, the average thickness of the organic resin coating layer 15'is measured by observing the cross section of the zinc-based plated steel sheet 1'including the organic resin coating layer 15'in the thickness direction. That is, the position of the organic resin coating layer 15'is specified from the cross section, and the thickness thereof is measured at a plurality of places. Then, the arithmetic mean value of the measured values is taken as the average thickness of the organic resin coating layer 15'. The minimum value of the thickness measured at each measurement point is preferably 0.1 μm or more. This is because if the minimum thickness is less than 0.1 μm, the corrosion resistance at that location may be lower than at other locations.

<7. Manufacturing method of galvanized steel sheet>
(7-1. Preparation process)
Next, a method for manufacturing the galvanized steel sheet 1'according to the modified example of the present embodiment will be described. First, the steel sheet 11'with the adjusted surface roughness is degreased with an alkaline solution. Then, the oxide layer covering the surface of the steel sheet 11'is removed. Examples of the method for removing the oxide layer include pickling and annealing in a hydrogen gas atmosphere. For example, when zinc-based electroplating is performed, pickling may be performed. When the zinc-based hot-dip plating layer is formed, annealing may be performed.

(7-2. Zinc-based plating layer forming process)
Then, a zinc-based plating layer 13'is formed on the surface of the steel plate 11'. Here, as the method for forming the zinc-based plating layer 13', the electrogalvanizing method or the hot-dip galvanizing method is preferable as described above. Therefore, these plating methods will be described here.

(7.2-1. Zinc-based electroplating layer forming process)
In the modified example of this embodiment, a known electrogalvanizing method can be used. Examples of the electroplating bath used in the electrogalvanizing method include a sulfuric acid bath, a chloride bath, a zincate bath, a cyanide bath, a pyrophosphate bath, a boric acid bath, a citric acid bath, other complex baths, and combinations thereof. Can be mentioned. In the electrozinc alloy plating bath, in addition to Zn ions, one or more monatomic ions or complex ions selected from Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, and Zr. By adding Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, and Zr, a zinc-based electroplating layer containing a desired amount can be formed. Among these additive elements, it is preferable to add any one or more elements selected from the group consisting of Fe, Co, and Ni. Further, it is more preferable to add an additive to the plating bath in order to stabilize the ions in the plating bath and control the plating characteristics.

The composition, temperature, flow velocity, current density at the time of plating, energization pattern, and the like of the electroplating bath may be appropriately selected so as to obtain a desired plating composition, and are not particularly limited. Further, the amount of adhesion of the zinc-based electroplating layer can be controlled by adjusting the current value and the time within the range of the current density at which the zinc-based electroplating layer has a desired composition.

(7-2-2. Zinc-based hot-dip plating layer forming process)
In the modified example of this embodiment, a known hot-dip galvanizing method can be used. First, the steel sheet 11'with the adjusted surface roughness is annealed. Then, the steel sheet 11'is immersed in a hot-dip plating bath and pulled up with the steel sheet temperature set to, for example, 450 ° C. As a result, a zinc-based hot-dip plating layer is formed on the surface of the steel sheet 11'. The amount of plating adhered is adjusted by gas wiping with nitrogen gas or the like when the steel sheet 11'is lifted. When the steel sheet 11'and the zinc-based hot-dip plating layer are alloyed, the zinc-based hot-dip plating layer is heated by, for example, IH so that the ultimate temperature after plating is, for example, 500 ° C.

Here, one or more of the above-mentioned additive elements selected from the group consisting of Fe, Al, Mg, and Si may be added to the hot-dip galvanizing bath. The composition, temperature, gas wiping flow velocity, plating adhesion amount, and the like of the hot-dip plating bath may be appropriately selected so as to obtain a desired plating composition, and are not particularly limited.

(7-3. Oxide layer forming step)
By the above steps, the zinc-based plating layer 13'is formed on the surface of the steel sheet 11. Then, an oxide layer 14'is formed on the surface of the zinc-based plating layer 13'. That is, the surface of the zinc-based plating layer 13'is blackened. Examples of the method for blackening the surface of the zinc-based plating layer 13' include the following methods. For example, a method of contacting an acidic aqueous solution of a mixture of nitrate and phosphoric acid with the zinc-based plating layer 13', a method of contacting an acidic aqueous solution of a mixture of tartaric acid and a fluoride with the zinc-based plating layer 13', and electrolytic treatment of nickel and antimony. And a method of bringing an acidic aqueous solution containing a fluorine compound into contact with the zinc-based plating layer 13'. According to these methods, since the oxide layer 14'composed of coarse oxide particles can be formed, rough irregularities can be formed on the surface of the oxide layer 14', and by extension, the oxide layer 14 can be formed. The surface roughness Ra of ‘’ can be more than 500 nm and 5000 nm or less. Moreover, this method is very simple and can be carried out in-line. The average thickness of the oxide layer 14'can be adjusted by appropriately adjusting the concentration of the acidic aqueous solution, the immersion time, and the like. On the other hand, the steam oxidation described in Patent Document 6 cannot be carried out in-line. Further, the unevenness of the surface of the oxide layer 14'is also very small.

(7-4. Hairline forming process)
Then, the recess 101'and the flat portion 103' described above are formed on the surface of the oxide layer 14'. That is, a hairline is formed on the surface of the oxide layer 14'. The specific hairline forming method is not particularly limited, and a method similar to the conventionally used hairline forming method can be used. Specific hairline forming methods include, for example, a method of polishing the surface of the oxide layer 14'with an abrasive (for example, a polishing belt and an abrasive grain brush), and pressing a roll having a texture on the surface of the oxide layer 14'. Examples thereof include a method of transferring the texture to the surface of the oxide layer 14', a method of grinding the surface of the oxide layer 14'with a grinding device, and the like.

The surface structure of the oxide layer 14'(for example, the depth, length, frequency, area ratio AR1, AR2, surface roughness RaA', RaB', etc. of the recess 101') is determined by, for example, the grain size of the abrasive and the abrasive. It is adjusted by adjusting the pressing force of the roll, the polishing time, the texture depth of the roll, the compressing force of the roll, the relative speed of the roll, the number of times the roll is pressed, and the like. In particular, in the modified example of the present embodiment, the average depth of the recess 101'is 0.1 μm or more and less than 3.0 μm, so that the generation of shavings can be suppressed. Further, by suppressing the grinding amount of the formed plating layer and oxide layer, it is possible to reduce the cost required for the portion that is not a product.

(7-5. Organic resin coating layer forming step)
Then, the organic resin coating layer 15'is formed on the surfaces of the recess 101'and the flat portion 103'. Although the organic resin coating layer 15'may be omitted, it is preferable to form the organic resin coating layer 15'from the viewpoint of enhancing characteristics such as corrosion resistance and blackness. The method for forming the organic resin coating layer 15'is not particularly limited, and examples thereof include a method using a paint. Specifically, a paint having the same composition as the organic resin coating layer 15'is applied to the surfaces of the recess 101'and the flat portion 103' and dried. As a result, the organic resin coating layer 15'is formed on the surfaces of the recess 101'and the flat portion 103'. By further applying a paint to the surface of the organic resin coating layer 15'and drying it, the organic resin coating layer 15'can be made into a multilayer structure. When the organic resin coating layer 15'has a multilayer structure, it is preferable to add a colorant, for example, a black pigment to any layer other than the bottom layer. Through the above steps, the galvanized steel sheet 1'according to the modified example of this embodiment is produced.

Here, the paint used for forming the organic resin coating layer 15'follows the surface shape of the recess 101'and the flat portion 103'at the moment when the paint is applied to the recess 101'and the flat portion 103', and the oxide It is preferable that the leveling after following the surface shape of the layer 14'is slow. That is, it is preferable that the viscosity of the paint is low at a high shear rate and the viscosity of the paint is high at a low shear rate. For example, when the shear rate is 0.1 [1 / sec], the shear viscosity is 10 [Pa · s] or more, and when the shear rate is 1000 [1 / sec], the shear viscosity is 0.01. It is preferably [Pa · s] or less.

When a paint using an aqueous emulsion resin is used, the shear viscosity can be adjusted by adding a hydrogen-bonding viscosity modifier to the paint. Such hydrogen-bonding viscosity modifiers bind each other by hydrogen bonds at low shear rates, so that the viscosity of the coating material can be increased. On the other hand, at a high shear rate, the hydrogen bond of the viscosity modifier is broken, so that the viscosity of the paint decreases. As a result, the shear viscosity of the paint can be adjusted to a value according to the painting conditions.

Further, the method of applying the paint to the recess 101'and the flat portion 103' is not particularly limited, and a known method can be appropriately used. Specific examples of the coating method include a spraying method, a roll coater method, a curtain coater method, a die coater method, and a dipping pulling method. Then, the paint is naturally dried or baked to form the organic resin coating layer 15'. The drying time, drying temperature, etc. may be adjusted as appropriate, but if the rate of temperature rise is slow, the time from the softening point of the resin component to the completion of baking may become long, and leveling may proceed. Therefore, it is preferable that the rate of temperature rise is high.

Hereinafter, the effects of the present invention will be specifically described with reference to examples of the invention.
Incidentally, Table 1A, which will be described later, Table 1B, Table 3A, the area _{S A} and the area _{S B} in Table 3B and Table 5B, respectively, the respective areas (although dimensionless in the case where the entire area of the observation field and 1.0 a value), the area _{S a} + area _S B = 1.0.
Further, Table 1A, among the column "Ra _A is 500nm ultra 5000nm or less of the total area" in Table 3A and Table 5B, the ratio of roughness satisfying area among the left column area _{S A} (maximum 1.0 ), And the right column is the actual area that satisfies the roughness condition. Therefore, the area _{S A} × [left column] = become [right column.
Similarly, Table 1B, among the column "Ra _B is 5nm super 500nm or less of the total area" in Table 3B and Table 5B, left column the proportion of roughness satisfying area among the area _{S B} (up to 1. 0), and the right column is the actual area satisfying the roughness condition. Therefore, the area _{S B} × [left column] = [the right column.
The average height difference in Tables 1B, 3B, and 5B is the average value of Δh shown in FIG. 2 or FIG. That is, the difference Δh between the average surface height of a certain rough portion 111 and the average surface height of the smooth portion 113 adjacent to the rough portion 111 is obtained, and this is calculated for each combination of the rough portion 111 and the smooth portion 113. Ask. Then, the average value of each of the obtained Δh was obtained, and this was used as the average height difference between Table 1 and Table 3.
The contents of the present invention are not limited by the contents described in the examples shown below.

(Experimental example 1: Electroplating; an example in which the rough part forms a hairline)
A steel sheet having a thickness of 0.6 mm (SPCD for drawing among cold-rolled steel sheets specified in JIS G 3141) is _{treated with a Na 4} SiO ₄ treatment liquid having a density of 30 g / L at a treatment liquid of 60 ° C. and a current. It was electrolyzed and washed with water under the conditions of a density of 20 A / dm ^{2 and a treatment time of 10 seconds.} _{Next, the electrolytically degreased steel sheet was immersed in an H 2} SO ₄ aqueous solution having a concentration of 50 g / L at 60 ° C. for 10 seconds and further washed with water to perform a plating pretreatment.

Next, No. 1 shown in Tables 1A to 1C below. 1-No. For the steel sheet sample of 28, a hairline was formed on the surface of the steel sheet by grinding before forming the zinc-based electroplating layer 13. In addition, No. 1 shown in Table 1 below. For the steel sheet sample of 29, a hairline was formed on the surface of the steel sheet by rolling before forming the zinc-based electroplating layer 13. The rolling method was a method in which a rolling roll having a pattern on the surface was pressed down on the design surface. The rolling speed was 200 mpm and the rolling roll diameter was 500 mm.

Next, all the steel sheet samples were subjected to zinc-based electroplating having the compositions shown in Tables 1A to 1C below to form the zinc-based electroplating layer 13. Here, in Table 1C below, the additive element described in the column of "plating composition" is an element added to the electroplating solution containing zinc as a main component, and when such a column is blank. Means electrogalvanized.

The Zn—Ni plating layer (Tables 1A to 1C: Nos. 1 to 18, 23 to 29) was formed as follows. When plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , Zn sulphate sulphate and Ni sulphate hexahydrate were adjusted in a ratio so as to have the composition shown in Table 1 below. Using a pH 2.0 plating bath containing a total of 1.2 M of Japanese product and Ni-sulfate hexahydrate and 50 g / L of anhydrous sodium sulfate, the amount of adhesion was the value shown in Tables 1A to 1C. The plating time was adjusted so as to be.

The Zn—Fe plating layer (Tables 1A to 1C: No. 19) was formed as follows. When plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , the Zn heptahydrate sulfate and Fe (II) sulphate heptahydrate are adjusted in a ratio so as to have the compositions shown in Tables 1A to 1C below. Using a plating bath having a pH of 2.0 containing a total of 1.2 M of Zn heptahydrate sulfate and Fe (II) sulphate heptahydrate and 50 g / L of anhydrous sodium sulfate, the amount of adhesion is shown in the table. The plating time was adjusted so as to have the values shown in Table 1C from 1A.

The Zn—Co plating layer (Tables 1A to 1C: No. 20) was formed as follows. Sulfuric acid, which was prepared by adjusting Zn heptahydrate sulfate and Co heptahydrate sulfate in a ratio such that the compositions shown in Tables 1A to 1C below were obtained when plating was performed at a bath temperature of 50 ° C. and a current density of 50 A / dm ^2. Using a pH 2.0 plating bath containing a total of 1.2 M of Zn heptahydrate and Co sulphate sulphate and 50 g / L of anhydrous sodium sulfate, the amount of adhesion is shown in Tables 1A to 1C. The plating time was adjusted so that the value would be the same.

The Zn-Ni-Fe-Co plating layer (Tables 1A to 1C: No. 21) was formed as follows. When plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , the composition of Table 1A to Table 1C below is obtained with Zn sulphate hydrate, Ni hexahydrate sulphate and Co sulphate sulphate. The sum of Zn sulphate heptahydrate, Ni sulphate hexahydrate, Fe (II) sulphate heptahydrate, and Co sulphate heptahydrate prepared by adjusting Japanese product and Fe (II) sulfate heptahydrate. Using a plating bath having a pH of 2.0 containing 1.2 M and 50 g / L of anhydrous sodium sulfate, the plating time was adjusted so that the amount of adhesion was as shown in Tables 1A to 1C.

The Zn plating layer (Tables 1A to 1C: No. 22) was formed as follows. Adhesion amount when plating with a pH 2.0 plating bath containing 1.2 M of Zn sulphate heptahydrate and 50 g / L of anhydrous sodium sulfate at a bath temperature of 50 ° C. and a current density of 50 A / dm ^2. The plating time was adjusted so that the values shown in Tables 1A to 1C were obtained.

In all the above plating treatments, the plating solution was flowed so that the relative flow velocity with respect to the steel sheet was 1 m / sec. The composition of the obtained plating layer is obtained by immersing the plated steel sheet in 10% by mass hydrochloric acid containing an inhibitor (NO.700AS manufactured by Asahi Chemical Co., Ltd.), dissolving and peeling, and analyzing the dissolved solution with ICP. confirmed.

In addition, as the above reagents, general reagents (zinc sulfate heptahydrate, anhydrous sodium sulfate, hydrochloric acid, sulfuric acid (pH adjustment)) were used.

In addition, No. 1-No. The steel sheet sample of 29 was adjusted as follows. After forming the zinc-based electroplating layer 13, the surface of the zinc-based electroplating layer 13 is brush-polished so that the surface shapes of the recesses 101 and the non-hairline portion 103 shown in Tables 1A to 1C are obtained. The grain size of the polishing paper, the rolling force, the number of times of polishing, etc.) were adjusted as appropriate. As a result, the surface shape of the zinc-based electroplating layer 13 was formed such that the recess 101 was composed of the rough portion 111 and the non-hairline portion 103 was composed of the smooth portion 113.

After that, No. 2-No. An acidic aqueous solution (sodium nitrate 120 g / L, phosphoric acid 45 g / L: pH 0.6, 30 ° C.) was spray-sprayed on the steel plate samples 26, 28, and 29, and the oxide layer 14 was sprayed on the surface of the zinc-based electroplating layer 13. (Specifically, an oxide layer mainly composed of Zn) was formed. The thickness of the oxide layer was adjusted by the temperature of the acidic aqueous solution and the spraying time. The thickness of the oxide layer was determined by observing the cross section with TEM-EDS, and was measured by changing the measurement magnification of TEM-EDS according to the thickness.
The underline in the table indicates that it is outside the specified range of the present invention.

Boundary between the coarse portion 111 and the smoothing portion 113, the hairline orthogonal direction a and the thickness direction of the cross section, the lowest point from the highest point H ₁ of the oxide layer 14 within the range of the observation width 1cm along the hairline orthogonal direction It was located on a virtual straight line which extends parallel to the height a and the hairline orthogonal direction of maximum height Ry 1/3 minus the H _0.

The various surface roughness, surface height, number of hairlines, area ratio, etc. of the rough portion (A) and the smooth portion (B) in the oxide layer 14 shown in Tables 1A to 1C are in the height direction. The measurement was performed according to the above method using a laser microscope / VK-9710 manufactured by KEYENCE Corporation having a display resolution of 1 nm or more and a display resolution in the width direction of 1 nm or more. The amount of plating adhered was analyzed by FE-EPMA from the direction perpendicular to the surface. Then, the amount of plating adhered was calculated from the thickness of the Zn-based plating layer excluding the oxide layer formed on the outermost layer, the average composition of the plating layer, and the specific gravity of each metal.
In Table 1A and Table 1B, Ra _A or Ra _B is the left column in the column of the following total area 500nm ultra 5000nm indicates the value of the area _{S A} or area _{S B} × total area.

A transparent organic resin coating layer was formed on the above-mentioned plated steel sheet having a hairline (steel sheet excluding No. 26). The transparent organic resin coating layer was formed by the following method. That is, a urethane resin (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Superflex 170) and a melamine resin (manufactured by Ornex Japan Co., Ltd., Cymel 327) were mixed so as to have a solid content mass ratio of 85:15. After that, one or more of black pigment (manufactured by Toyo Color Co., Ltd., EMF Black HK-3) or blue pigment (manufactured by Dainichiseika Co., Ltd., AF Blue E-2B) was used as a coloring pigment, and the mass concentration in the coating film was 2 mass%. Alternatively, it was added so as to be 15 mass%. Polyethylene wax (Chemipal W500, manufactured by Mitsui Chemicals, Inc.) was added so that the concentration in the dry film was 2% by mass, and the mixture was stirred. Further, the obtained mixture was diluted with water to prepare treatment liquids having various concentrations and viscosities. These treatment liquids were applied to the surface of the steel sheet with a roll coater. At this time, the dry film thickness was adjusted to be the thickness shown in Table 1C below. The painted steel sheet was held in a hot air furnace kept at 280 ° C. for 30 seconds. The ultimate temperature of the steel sheet was 210 ° C., and after heating, it was cooled by spraying water.

The blackness (L ^* value) of the prepared steel sheet sample was measured according to the method described above.
Next, the conspicuity of the hairline (transparency (appearance of the hairline)) was evaluated for the prepared steel sheet sample. The hairlines formed on the steel sheet sample were installed vertically so as to be up and down, and the hairlines were observed at different distances, and the conspicuity was evaluated from the distance at which the hairlines could be visually confirmed according to the following criteria. The results obtained are summarized in Table 2 below.

(Evaluation criteria)
Hairline can be seen from a distance of 5: 1 m 4:70 cm or more, hairline can be seen from a distance of less than 1 m 3: Hairline can be seen from a distance of 50 cm or more and less than 70 cm Visible Hairline is not visible from a distance of 1:30 cm

A clear coating was applied to the hairline stainless steel specified in JIS G4305: 2012. The clear coating film is coated with a commercially available polyester / melamine paint (NSC200HQ manufactured by Nippon Paint Industrial Coatings Co., Ltd.) and baked and cured in a hot air oven for 30 seconds to change the coating film thickness. Was compared. The results obtained are summarized in Table 2 below.

(Evaluation criteria)
5: Stainless steel (no coating) equivalent or better metallic feeling 4: Stainless steel (coating thickness 5 μm) equivalent 3: Stainless steel (coating thickness 10 μm) equivalent 2: Stainless steel (painting thickness 30 μm) equivalent 1: Metallic feeling is not felt

The corrosion resistance of the obtained zinc-based electroplated steel sheet was evaluated by the following method.
That is, a test piece having a width of 70 mm and a length of 150 mm was prepared from each of the obtained galvanized steel sheets. The edge and the back surface were tape-sealed, and a salt spray test (JIS Z 2371) was performed. Then, the white rust generation area ratio of the unsealed portion after 24 hours was visually observed and evaluated according to the following evaluation criteria. The white rust generation area ratio is a percentage of the area of the white rust generation site with respect to the area of the observation site. The results obtained are summarized in Table 2 below.

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

The processing adhesion (adhesion with the organic resin coating layer) of the obtained zinc-based electroplated steel sheet was evaluated by the following method.
That is, a test piece having a width of 50 mm and a length of 50 mm was prepared from each of the obtained galvanized steel sheets. After bending the obtained test piece at 180 °, a tape peeling test was performed on the outside of the bent portion. The appearance of the tape peeled portion was observed with a loupe having a magnification of 10 times, and evaluated according to the following evaluation criteria. The bending process was carried out in an atmosphere of 20 ° C. with a 0.5 mm spacer in between. The results obtained are summarized in Table 2 below.

(Evaluation criteria)
5: No peeling is observed in the organic resin coating layer 4: Peeling is observed in a very small part of the organic resin coating layer (peeling area ≤ 2%)
3: Peeling is observed on some organic resin coating layers (2% <peeling area ≤ 10%)
2: Peeling is observed in the organic resin coating layer (10% <peeling area ≤ 20%)
1: Peeling is observed on the organic resin coating layer (peeling area> 20%)

No. 1-No. Of the 29 steel plate samples, No. 1 and No. In the comparative material of No. 2, the oxide layer was not formed, the thickness of the oxide layer did not meet the regulation, and the blackness was inferior.
In addition, No. In the comparative material of No. 7, the thickness of the oxide layer was larger than the specified value, and the processing adhesion was inferior.
In addition, No. In the comparative material of No. 27, since the concentration of the colored pigment in the organic resin coating layer was high, the L ^* value was 40 or less even in the absence of the oxide layer. However, the organic resin coating layer was highly concealed and the hairline was concealed and could not be seen.

As is clear from Table 2 above, the galvanized steel sheet according to the embodiment of the present invention has good corrosion resistance, high blackness and hairline appearance even when an inexpensive steel material is used. Moreover, it can be seen that it is excellent in metallic feeling and processing adhesion.
No. using a blue pigment as a coloring pigment. It can be seen that 28 also has good corrosion resistance, has a high blackness and a hairline appearance, and is excellent in metallic feeling and processing adhesion.

(Experimental example 2: Electroplating, an example in which a smooth part forms a hairline)
A steel sheet having a thickness of 0.6 mm (SPCD for drawing among cold-rolled steel sheets specified in JIS G 3141) is _{treated with a Na 4} SiO ₄ treatment liquid having a concentration of 30 g / L at a treatment liquid of 60 ° C. and a current density. It was electrolytically degreased and washed with water under the conditions of 20 A / dm ^{2 and a treatment time of 10 seconds.} _{Next, the electrolytically degreased steel material was immersed in an aqueous solution of H 2} SO ₄ at a concentration of 50 g / L at 60 ° C. for 10 seconds and further washed with water to perform a plating pretreatment.

Next, all the steel sheet samples were subjected to zinc-based electroplating having the compositions shown in Tables 3A to 3C below to form the zinc-based electroplating layer 13. Here, in Tables 3A to 3C below, the "additive element" described in the column of "plating composition" is an element added to the electroplating liquid. When such a column is blank (Table 3C: No. 61), it means that electrogalvanization has been performed.

Further, the Zn—Ni plating layer (Tables 3A to 3C: Nos. 41 to 57, 62 to 68) was formed as follows. When plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , Zn sulphate sulphate and Ni sulphate hexahydrate were adjusted to the ratios shown in Table 3 below. Table 3B shows the amount of plating adhered after hairline formation using a plating bath of pH 2.0 containing a total of 1.2 M of Japanese product and Ni-sulfate hexahydrate and 50 g / L of anhydrous sodium sulfate. The plating time was adjusted so as to be a value.

The Zn—Fe plating layer (Tables 3A to 3C: No. 58) was formed as follows. Sulfuric acid, which was prepared by adjusting Zn sulfate heptahydrate and Fe (II) sulfate heptahydrate at a ratio such that the composition shown in Table 3 below was obtained when plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ^2. Using a pH 2.0 plating bath containing a total of 1.2 M of Zn heptahydrate and Fe (II) sulfate heptahydrate and 50 g / L of anhydrous sodium sulfate, the amount of plating adhered after hairline formation. The plating time was adjusted so that the value shown in Table 3 was obtained.
The Zn—Co plating layer (Tables 3A to 3C: No. 59) was formed as follows. Sulfuric acid, which was prepared by adjusting Zn heptahydrate sulfate and Co heptahydrate sulfate in a ratio such that the compositions shown in Tables 3A to 3C below were obtained when plating was performed at a bath temperature of 50 ° C. and a current density of 50 A / dm ^2. Table 3 shows the amount of plating adhered after hairline formation using a pH 2.0 plating bath containing a total of 1.2 M of Zn heptahydrate and Co sulphate heptahydrate and 50 g / L of anhydrous sodium sulfate. The plating time was adjusted so as to have the value shown in.

The Zn-N-Fe-Co plating layer (Tables 3A to 3C: No. 60) was formed as follows. When plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , the compositions shown in Tables 3A to 3C below are such that Zn sulphate hydrate, Ni hexahydrate sulphate and Co sulphate sulphate have the same composition. The sum of Zn sulphate heptahydrate, Ni sulphate hexahydrate, Fe (II) sulphate heptahydrate and Co sulphate heptahydrate prepared by adjusting Japanese product and Fe (II) sulfate heptahydrate. Using a plating bath having a pH of 2.0 containing 1.2 M and 50 g / L of anhydrous sodium sulfate, the plating time was adjusted so that the amount of plating adhered after hairline formation was the value shown in Table 3B.

In all the above plating treatments, the plating solution was flowed so that the relative flow velocity with respect to the steel sheet was 1 m / sec. The composition of the obtained plating layer is obtained by immersing the plated steel sheet in 10% by mass hydrochloric acid containing an inhibitor (NO.700AS manufactured by Asahi Chemical Co., Ltd.), dissolving and peeling, and analyzing the dissolved solution with ICP. confirmed.

In addition, as the above reagents, general reagents (zinc sulfate heptahydrate, anhydrous sodium sulfate, hydrochloric acid, sulfuric acid (pH adjustment)) were used.

In addition, No. 1 shown in Tables 3A to 3C below. 41-No. For the steel sheet sample of 67, after forming the zinc-based electroplating layer 13, a hairline was formed on the surface of the steel sheet by grinding. The grinding method was a method in which a roll having a pattern on the surface was rotated and pressed down onto a design surface having a zinc-based electroplating layer 13 (that is, the surface of the zinc-based electroplating layer 13). The grinding brush was rotated in the direction opposite to the plate passing direction of the steel plate sample. The hairline depth was adjusted by the brush material, the rotation speed, and the load between the brush and the steel plate. The hairline density was adjusted by the thread diameter and density of the brush.

Next, No. 1 shown in Tables 3A to 3C below. For the 68 steel sheet sample, after the zinc-based electroplating layer 13 was formed, a hairline was formed on the surface of the zinc-based electroplating steel sheet 1 by rolling. The rolling method was a method in which a rolling roll having a pattern on the surface was pressed onto the design surface of the zinc-based electroplated steel sheet 1 (that is, the surface of the zinc-based electroplated layer 13). The rolling speed was 50 mpm.

After that, No. 42-No. An acidic aqueous solution (sodium nitrate 120 g / L, phosphoric acid 45 g / L: pH 0.6, 30 ° C.) was spray-sprayed on the steel plate samples of 65, 67, and 68, and the oxide layer 14 was sprayed on the surface of the zinc-based electroplating layer 13. (Specifically, an oxide layer mainly composed of Zn) was formed. The thickness of the oxide layer was adjusted by the temperature of the acidic aqueous solution and the spraying time. The underline in the table indicates that it is outside the specified range of the present invention.

By the above procedure, the surface shape of the oxide layer 14 is formed such that the concave portion 101 is composed of the smooth portion 113 and the non-hairline portion 103 is composed of the rough portion 111.
Incidentally, the boundary between the coarse portion 111 and the smoothing portion 113, the hairline orthogonal direction a and the thickness direction of the cross section, from the highest point H ₁ of the oxide layer 14 within the range of the observation width 1cm along the hairline orthogonal direction It is assumed that the height is 1/3 of the maximum height Ry minus the lowest point H _{0 and is on a virtual straight line parallel to the hairline orthogonal direction.}

Here, various surface roughness, surface height, number of hairlines, area ratio, etc. of the rough portion (A) and the smooth portion (B) in the oxide layer 14 shown in Tables 3A to 3C are in the height direction. The measurement was performed according to the above method using a laser microscope / VK-9710 manufactured by KEYENCE Corporation, which has a display resolution of 1 nm or more and a display resolution in the width direction of 1 nm or more. The amount of plating adhered is analyzed by FE-EPMA from the direction perpendicular to the surface, and calculated from the thickness of the Zn-based plating layer excluding the oxide layer formed on the outermost layer, the average composition of the plating layer, and the specific gravity of each metal. bottom.
In Table 3A and Table 3B, Ra _A or Ra _B is the left column in the column of the following total area 500nm ultra 5000nm indicates the value of the area _{S A} or area _{S B} × total area.

A transparent organic resin coating layer was formed on the above-mentioned plated steel sheet having a hairline (steel sheet excluding No. 65). The transparent organic resin was formed by the following method. That is, a urethane resin (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Superflex 170) and a melamine resin (manufactured by Ornex Japan Co., Ltd., Cymel 327) were mixed so as to have a solid content mass ratio of 85:15. After that, one or more of black pigment (manufactured by Toyo Color Co., Ltd., EMF Black HK-3) or blue pigment (manufactured by Dainichiseika Co., Ltd., AF Blue E-2B) was used as a coloring pigment, and the mass concentration in the coating film was 2 mass. It was added so as to be% or 15% by mass. Polyethylene wax (Chemipal W500, manufactured by Mitsui Chemicals, Inc.) was added so that the concentration in the dry film was 2% by mass, and the mixture was stirred. Further, the obtained mixture was diluted with water to prepare treatment liquids having various concentrations and viscosities. These treatment liquids were applied to the surface of the steel sheet with a roll coater. At this time, the dry film thickness was adjusted to be the thickness shown in Table 3C below. The painted steel sheet was held in a hot air furnace kept at 280 ° C. for 30 seconds. The ultimate temperature of the steel sheet was 210 ° C., and after heating, it was cooled by spraying water.

For each of the zinc-based electroplated steel sheets obtained as described above, the blackness, transparency (appearance of hairline), corrosion resistance, and processing adhesion were evaluated in the same manner as in Experimental Example 1. The evaluation method and evaluation criteria are the same as in Experimental Example 1. The results obtained are summarized in Table 4 below.

No. 41-No. Of the 68 steel samples, No. In the comparative examples of 41 and 42, the oxide layer was not formed, the thickness of the oxide layer did not meet the regulation, and the blackness was inferior.
In addition, No. In the comparative material 47, the thickness of the oxide layer was larger than specified, and the processing adhesion was inferior.

In addition, No. In the comparative example of 66, since the color pigment concentration in the organic resin coating layer was high, the L ^* value was 40 or less even in the absence of the oxide layer. However, the hiding property in the organic resin coating layer was high, and the hairline was hidden and could not be seen.

As is clear from Table 4 above, the galvanized steel sheet according to the embodiment of the present invention has good corrosion resistance, high blackness and hairline appearance even when an inexpensive steel material is used. Moreover, it can be seen that it is excellent in metallic feeling and processing adhesion.

(Experimental example 3: Hot plating, an example in which the rough part forms a hairline)
A steel sheet having a thickness of 0.6 mm (SPCD for drawing among cold-rolled steel sheets specified in JIS G 3141) is _{treated with a Na 4} SiO ₄ treatment liquid having a density of 30 g / L at a treatment liquid of 60 ° C. and a current. It was electrolyzed and washed with water under the conditions of a density of 20 A / dm ^{2 and a treatment time of 10 seconds.} Then, it was heated to 800 ° C. in a 5% hydrogen gas atmosphere and held for 5 minutes. Then, it was air-cooled to 450 ° C. to remove the oxide layer formed on the surface of the steel sheet.

Next, all the steel sheet samples were subjected to zinc-based hot-dip plating having the compositions shown in Tables 5A to 5D below to form the zinc-based hot-dip plating layer 13. Here, in Tables 5A to 5D below, the "additive element" described in the column of "plating composition" is an element added in the hot-dip plating bath. When such a column is blank (Table 5D: No. 100), it means that hot dip galvanizing has been performed.

Further, the Zn-Al-Mg plating layer (Tables 5A to 5D: No. 81-97, 101-107) has the compositions shown in Tables 5A to 5D below when plated at a plating bath temperature of 450 ° C. The plating bath composition was adjusted as described above. Further, the amount of plating adhesion was adjusted according to the gas wiping conditions after plating so that the amount of plating adhesion after hairline formation was the value shown in Table 5.

Further, the Zn—Al plating layer (Tables 5A to 5D: No. 98) was adjusted in plating bath composition so as to have the composition shown in Table 5 below when plated at a plating bath temperature of 650 ° C. Further, the plating adhesion amount was adjusted according to the gas wiping conditions after plating so that the plating adhesion amount after hairline formation was the value shown in Table 5C.

The Zn-Fe plating layer (Tables 5A to 5D: No. 99) is plated at a plating bath temperature of 500 ° C. so that the amount of plating adhesion after hairline formation is the value shown in Table 5C, and the gas after plating. Adjusted the wiping conditions. Further, Fe contained in the steel sheet and Zn contained in the zinc hot-dip plating layer were alloyed, and the plated steel sheet was heated at 500 ° C. so as to have the compositions shown in Tables 5A to 5D below.

Example No. in which hot dip galvanizing is performed. 100 was plated at a plating bath temperature of 500 ° C. Further, the plating adhesion amount was adjusted according to the gas wiping conditions after plating so that the plating adhesion amount after hairline formation was the value shown in Table 5C.

In all the above plating treatments, the composition of the obtained plating layer was obtained by immersing the plated steel sheet in 10% by mass hydrochloric acid containing an inhibitor (NO.700AS manufactured by Asahi Chemical Co., Ltd.) to dissolve and peel it off. The solution was confirmed by analyzing with ICP.

Next, No. 1 shown in Tables 5A to 5D below. 81-No. For the 107 steel sheet sample, after the zinc-based hot-dip plating layer 13 was formed, a hairline was formed on the surface of the zinc-based hot-dip-plated steel sheet 1 by grinding. The grinding method was a method in which a roll having a pattern on the surface was rotated and pressed down onto a design surface having a zinc-based hot-dip plating layer 13 (that is, the surface of the zinc-based hot-dip plating layer 13). The grinding brush was rotated in the direction opposite to the plate passing direction of the steel plate sample. The hairline depth was adjusted by the brush material, the rotation speed, and the load between the brush and the steel plate. The hairline density was adjusted by the thread diameter and density of the brush.

Next, No. 1 shown in Tables 5A to 5D below. 81-No. For the 107 steel sheet sample, after forming a hairline by grinding, unevenness was formed on the surface of the zinc-based hot-dip plated steel sheet 1 by rolling. The rolling method was a method in which a rolled roll having a pattern on the surface was pressed onto the design surface of the zinc-based hot-dip-plated steel sheet 1 (that is, the surface of the zinc-based electroplating layer 13).

After that, No. 82-105, No. An acidic aqueous solution (sodium nitrate 120 g / L, phosphoric acid 45 g / L: pH 0.6, 30 ° C.) was spray-sprayed on 107 steel samples, and an oxide layer 14 (specifically) was sprayed on the surface of the zinc-based electroplating layer 13. Formed an oxide layer mainly composed of Zn). The thickness of the oxide layer was adjusted by the temperature of the acidic aqueous solution and the spraying time. The underline in the table indicates that it is outside the specified range of the present invention.

By the above procedure, the surface shape of the oxide layer 14 is formed such that the concave portion 101 is composed of the smooth portion 113 and the non-hairline portion 103 is composed of the rough portion 111.
Incidentally, the boundary between the coarse portion 111 and the smoothing portion 113, the hairline orthogonal direction a and the thickness direction of the cross section, from the highest point H ₁ of the oxide layer 14 within the range of the observation width 1cm along the hairline orthogonal direction It is assumed that the height is 1/3 of the maximum height Ry minus the lowest point H _{0 and is on a virtual straight line parallel to the hairline orthogonal direction.}

Here, various surface roughness, surface height, number of hairlines, area ratio, etc. of the rough portion (A) and the smooth portion (B) in the oxide layer 14 shown in Tables 5A to 5D are in the height direction. The measurement was performed according to the above method using a laser microscope / VK-9710 manufactured by KEYENCE Corporation, which has a display resolution of 1 nm or more and a display resolution in the width direction of 1 nm or more. The amount of plating adhered is analyzed by FE-EPMA from the direction perpendicular to the surface, and calculated from the thickness of the Zn-based plating layer excluding the oxide layer formed on the outermost layer, the average composition of the plating layer, and the specific gravity of each metal. bottom.
In Table 5B, Ra _A or Ra _B is the left column in the column of the total area of less than 500nm ultra 5000nm indicates the value of the area _{S A} or area _{S B} × total area.

A transparent organic resin coating layer was formed on the above-mentioned plated steel sheet having a hairline (steel sheet excluding No. 105). The transparent organic resin coating layer was formed by the following method. That is, a urethane resin (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Superflex 170) and a melamine resin (manufactured by Ornex Japan Co., Ltd., Cymel 327) were mixed so as to have a solid content mass ratio of 85:15. After that, one or more of black pigment (manufactured by Toyo Color Co., Ltd., EMF Black HK-3) or blue pigment (manufactured by Dainichiseika Co., Ltd., AF Blue E-2B) was used as a coloring pigment, and the mass concentration in the coating film was 2 mass. It was added so as to be% or 15% by mass. Polyethylene wax (Chemipal W500, manufactured by Mitsui Chemicals, Inc.) was added so that the concentration in the dry film was 2% by mass, and the mixture was stirred. Further, the obtained mixture was diluted with water to prepare treatment liquids having various concentrations and viscosities. These treatment liquids were applied to the surface of the steel sheet with a roll coater. At this time, the dry film thickness was adjusted to be the thickness shown in Table 5D below. The painted steel sheet was held in a hot air furnace kept at 280 ° C. for 30 seconds. The ultimate temperature of the steel sheet was 210 ° C., and after heating, it was cooled by spraying water.

For each of the zinc-based hot-dip plated steel sheets obtained as described above, the blackness, transparency (appearance of hairline), corrosion resistance, and processing adhesion were evaluated in the same manner as in Experimental Example 1. The evaluation method and evaluation criteria are the same as in Experimental Example 1. The results obtained are summarized in Table 6 below.

No. 81-No. Of the 107 steel samples, No. In the comparative examples of 81 and 82, the oxide layer was not formed, the thickness of the oxide layer did not meet the regulation, and the blackness was inferior.
In addition, No. In the comparative material of 87, the thickness of the oxide layer was larger than specified, and the processing adhesion was inferior.

In addition, No. In the comparative example of 106, since the color pigment concentration in the organic resin coating layer was high, the L ^* value was 40 or less even in the absence of the oxide layer. However, the organic resin coating layer was highly concealed and the hairline was concealed and could not be seen.

As is clear from Table 6 above, the galvanized steel sheet according to the present invention has good corrosion resistance, good blackness and hairline appearance, even when an inexpensive steel material is used. It can be seen that it is excellent in metallic feeling and processing adhesion.

In the above-mentioned examples, the case where the surface of the zinc-based plating layer to which the hairline is imparted is covered with the oxide layer has been described. In the following, examples of imparting hairlines to the surface of the oxide layer will be described with reference to Tables 7A to 8.

<1. Preparation of test sample>
Next, an embodiment of a modified example of the present embodiment will be described. In this example, first, a test sample of a galvanized steel sheet was prepared by the following steps. The outline of the manufacturing process is shown in Table 7A. The underline in the table indicates that it is outside the specified range of the present invention.

(1-1. Preparation process)
A steel sheet having a thickness of 0.6 mm (SPCD for drawing among cold-rolled steel sheets specified in JIS G 3141) was _{ionized and greased with a Na 4} SiO ₄ treatment liquid having a concentration of 30 g / L and washed with water. .. Here, the degreasing conditions were a treatment liquid of 60 ° C., a current density of 20 A / dm ² , and a treatment time of 10 seconds. Then, the oxide layer covering the surface of the steel sheet was removed. Specifically, in the case of zinc-based electroplating, the electrolytically degreased steel sheet was _{immersed in an H 2} SO ₄ aqueous solution having a concentration of 50 g / L kept at 60 ° C. for 10 seconds, and further washed with water. When zinc-based hot-dip plating was performed, the steel sheet was heated to 800 ° C. in a 5% hydrogen gas atmosphere and held for 5 minutes. Then, it was air-cooled to 450 ° C.

(1-2. Zinc-based plating layer forming process)
Then, a zinc-based plating layer forming step was performed. The specific process is as follows. The composition of the obtained plating layer is obtained by immersing the plated steel sheet in 10% by mass hydrochloric acid containing an inhibitor (NO.700AS manufactured by Asahi Chemical Co., Ltd.), dissolving and peeling, and analyzing the dissolved solution with ICP. confirmed.

(1-2-1. Zn—Ni electrozinc alloy plating layer forming step: No. 1'to 17', 21' to 31', 34' to 37')
When the steel sheet is plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , the composition of the electrozinc alloy plating layer is shown in Table 2-1 below. Japanese products were mixed. Then, a plating bath having a pH of 2.0 containing a total of 1.2 M of Zn sulphate heptahydrate and Ni sulphate hexahydrate and 50 g / L of anhydrous sodium sulfate was prepared. Then, electrogalvanization was performed using this plating bath at a bath temperature of 50 ° C. and a current density of 50 A / dm ² . Here, the plating time was adjusted so that the amount of plating adhered was the value shown in Table 7C. Further, the plating solution was flowed so that the relative flow velocity with respect to the steel sheet was 1 m / sec.

(1-2-2. Zn-Fe electrozinc alloy plating layer forming step: No. 18')
When the steel sheet is plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , Zn heptahydrate sulfate and Fe (II) sulfate are used so that the electrolytic zinc alloy plating layer has the composition shown in Table 2-1 below. ) The heptahydrate was mixed. Then, a plating bath having a pH of 2.0 containing a total of 1.2 M of Zn sulfate heptahydrate and Fe (II) sulfate heptahydrate and 50 g / L of anhydrous sodium sulfate was prepared. Then, electrogalvanization was performed using this plating bath at a bath temperature of 50 ° C. and a current density of 50 A / dm ² . Here, the plating time was adjusted so that the amount of plating adhered was the value shown in Table 2-1. Further, the plating solution was flowed so that the relative flow velocity with respect to the steel sheet was 1 m / sec.

(1-2-3. Zn-Co electrozinc alloy plating layer forming step: No. 19')
When the steel sheet is plated at a bath temperature of 50 ° C. and a current density of 50 A / dm ² , the composition of the electrozinc alloy plating layer is shown in Table 2-1 below. Japanese products were mixed. Then, a plating bath having a pH of 2.0 containing a total of 1.2 M of Zn heptahydrate sulfate and Co heptahydrate sulfate and 50 g / L of anhydrous sodium sulfate was prepared. Then, electrogalvanization was performed using this plating bath at a bath temperature of 50 ° C. and a current density of 50 A / dm ² . Here, the plating time was adjusted so that the amount of plating adhered was the value shown in Table 7C. Further, the plating solution was flowed so that the relative flow velocity with respect to the steel sheet was 1 m / sec.

(1-2-5. Electrogalvanizing layer forming step: No. 20')
A plating bath having a pH of 2.0 containing 1.2 M of Zn sulphate heptahydrate and 50 g / L of anhydrous sodium sulfate was prepared. Then, electrogalvanization was performed using this plating bath at a bath temperature of 50 ° C. and a current density of 50 A / dm ² . Here, the plating time was adjusted so that the amount of plating adhered was the value shown in Table 7C. Further, the plating solution was flowed so that the relative flow velocity with respect to the steel sheet was 1 m / sec.

As the above reagents, general reagents (Zn sulphate heptahydrate, anhydrous sodium sulfate, hydrochloric acid, sulfuric acid (pH adjustment), etc.) were used.

(1-2-7. Zn-Al-Mg hot-dip zinc alloy plating layer forming step: No. 32', 33')
The composition of the plating bath was adjusted so that the hot-dip zinc alloy plating layer had the composition shown in Table 2-1 below when the steel sheet was plated at a plating bath temperature of 450 ° C. Then, the steel sheet whose temperature was maintained at 450 ° C. was immersed in a plating bath at 450 ° C., and then the steel sheet was pulled up to form a hot-dip galvanized alloy plating layer on the surface of the steel sheet. Then, gas wiping was performed so that the amount of plating adhered was the value shown in Table 7C.

(1-3. Oxide layer forming step)
In the oxide layer forming step, an oxide layer was formed on the surface of the zinc-based plating layer by a method different for each steel sheet. No. In 1'to 31'and 34' to 37', an oxide layer was formed by the following blackening treatment 1, and No. In 32', an oxide layer was formed by the following blackening treatment 3, and No. In 33', an oxide layer was formed by the following blackening treatment 4. The average thickness and composition of the obtained oxide layer were measured by the method described above.

Blackening treatment 1: Apply an acidic aqueous solution (sodium nitrate (manufactured by Kanto Chemical Co., Inc.) 120 g / L, phosphoric acid (manufactured by Kanto Chemical Co., Ltd.) 45 g / L, pH 0.6, 30 ° C.) to the surface of the zinc-based plating layer 3 Sprayed for seconds.
Blackening treatment 3: Acidic aqueous solution (nickel sulfate hexahydrate (manufactured by Kanto Chemical Holding Co., Ltd.) 45 g / L, antimony chloride (III) (manufactured by Kanto Chemical Holding Co., Ltd.) 2 g / L, hydroborofluoric acid (Kanto Chemical Holding Co., Ltd.) Each test material was immersed in 7 g / L, pH 1.0, temperature 70 ° C.) for 3 seconds.
Blackening treatment 4: With reference to Example 2 of Patent Document 6 (Japanese Unexamined Patent Publication No. 2017-218647), steam treatment (temperature: 120 ° C., relative humidity: 95%, oxygen concentration: 1.0%, treatment time 20h). ) Was performed.
All of the test materials were blackened, washed with water, and dried. The pH of the acidic aqueous solution of the blackening treatments 1 to 3 was adjusted with sulfuric acid (manufactured by Kanto Chemical Holding Co., Ltd.).

(1-4. Hairline forming process)
Then, the surface of the oxide layer was polished with an abrasive grain brush to form the above-mentioned recesses and flat portions on the surface of the oxide layer. Here, the average depth of the recess 101', the average length along the length direction, the number of lines per unit width, the area ratios AR1 and AR2, the area ratio ratio AR1 / AR2, and the surface roughness RaA'are more than 5 nm and 500 nm or less. (Table 7B describes the presence or absence of the average roughness RaA of the recesses) and the region where the surface roughness RaB'of the flat portion 103'is more than 500 nm and 5000 nm or less (Table 7B shows the average roughness of the flat portion). The grain size, reducing force, and polishing time of the abrasive grain brush were adjusted so that the presence or absence of degree RaB') was the value or category shown in Table 7A and Table 7B. “-” Indicates that evaluation is not possible with respect to the presence or absence of smooth regions and coarse regions. The obtained surface structure was specified by the method described above.

(1-5. Organic resin film forming step)
In some steel sheets (No. 1'to 24', 26' to 37'), an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion. Of these, No. For steel sheets other than 31, the organic resin coating layer was two layers (upper layer and lower layer). First, a urethane resin (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Superflex 170) and a melamine resin (manufactured by Ornex Japan Co., Ltd., Cymel 327) were mixed so that the solid content mass ratio was 85:15. On the other hand, black pigments (EMF Black HK-3 manufactured by Toyo Color Co., Ltd.) and blue pigments (AF Blue E-2B manufactured by Dainichiseika Co., Ltd.) were prepared as coloring pigments. Then, by mixing these materials with water, a pigment-free colorless paint, a black paint 1 containing a black pigment in an amount of 2% by mass based on the total mass of solids (including the pigment), and a black pigment in an amount of 15% by mass. A blue paint containing 2% by mass of the black pigment 2 and the blue pigment contained in the above was prepared. Next, a Si-based additive containing Si as an active ingredient (manufactured by Nissan Chemical Co., Ltd./Snowtex N), a P-based additive containing P as an active ingredient (manufactured by Kanto Chemical Co., Ltd./ammonium phosphate), and Zr are contained as active ingredients. A Zr-based additive (manufactured by Kishida Chemical Co., Ltd./ammonium ammonium carbonate) was prepared. No. In 36', the organic resin coating layer was two layers, and the upper layer and the lower layer contained a black pigment.

No. In 1'to 30', 32'to 35', and 37', first, a colorless paint to which a Si-based additive was added was applied to the surfaces of the concave portion and the flat portion with a roll coater. Then, the galvanized steel sheet coated with the colorless paint was held in a hot air furnace kept at 280 ° C. for 30 seconds. The ultimate temperature of the galvanized steel sheet was 210 ° C., and after heating, it was cooled by spraying water. By the above steps, a lower layer containing no black pigment was formed. Then, the black paint 1 to which the Si-based additive was added was applied onto the lower layer with a roll coater. After that, the same process as above was performed. As a result, an upper layer containing a black pigment was formed on the lower layer. The amount of each paint applied was adjusted so that the overall average thickness of the upper layer and the lower layer had the values shown in Table 7C. The amount of each paint applied was set to be substantially the same so that the upper layer and the lower layer had the same thickness. By the above steps, an organic resin coating layer was further formed on the surfaces of the recess and the flat portion. The average thickness was measured by the method described above.

No. In 26', the paint for the upper layer was black paint 2, and the additives for the paints for the upper layer and the lower layer were Si-based additives. By performing the same treatment as 1'to 24', an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion.

No. In 27', the paint for the upper layer was a blue paint, and the additives for the paints for the upper layer and the lower layer were Si-based additives. By performing the same treatment as in 1', an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion.

No. In 28', the paint for the upper layer was black paint 1, and the additives for the paints for the upper layer and the lower layer were P-based additives. By performing the same treatment as in 1', an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion.

No. In 29', the paint for the upper layer was black paint 1, and the additives for the paints for the upper layer and the lower layer were Zr-based additives. By performing the same treatment as in 1', an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion.

No. In No. 30', except that no additive was added to the paints for the upper layer and the lower layer, No. By performing the same treatment as in 1', an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion.

No. In 31', No. 1 except that the lower layer was not formed. By performing the same treatment as in 1', an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion.

No. In 36', No. 3 except that the paint for the lower layer was black paint 1. By performing the same treatment as in 1', an organic resin coating layer was further formed on the surfaces of the concave portion and the flat portion.

<2. Evaluation of test sample>
Samples of galvanized steel sheets produced by the above steps were evaluated by the following methods. The results are summarized in Table 8.

(2-1. Blackness (L ^* value))
The L ^* value in the CIE1976L ^* a ^* b ^* color system was measured with a colorimeter (CR-400 manufactured by Konica Minolta). If the L ^* value is 50 or less, it can be said that a high degree of blackness is achieved. The L ^* value is preferably 40 or less.

(2-2. Appearance of hairline (easiness to see hairline))
The hairlines (recesses) formed in the prepared test sample were vertically installed so as to be up and down, and the hairlines were visually observed by changing the distance between the observer and the test sample. Then, the appearance of the hairline was evaluated based on the distance at which the hairline could be visually confirmed and the following evaluation criteria.

(Evaluation criteria)
The hairline can be seen from a distance of 5: 1 m.
The hairline can be visually recognized from a distance of 4: 70 cm or more and less than 1 m.
The hairline can be visually recognized from a distance of 3: 50 cm or more and less than 70 cm.
The hairline can be visually recognized from a distance of 2:30 cm or more and less than 50 cm.
The hairline is not visible from a distance of 1:30 cm.

(2-3. Metallic feeling)
A clear paint was applied to the hairline stainless steel sheet specified in JIS G4305: 2012. A commercially available polyester / melamine paint (Nippon Paint Industrial Coatings Co., Ltd., NSC200HQ) was used as the clear paint, and the coating was performed with a bar coater. Then, the stainless steel sheet coated with the paint was baked and hardened in a hot air furnace for 30 seconds. By such a step, a plurality of types of comparative samples having different coating film thicknesses were prepared. Then, the metallic feeling of the test sample and these comparative samples was compared, and the metallic feeling of the test sample was evaluated based on the following evaluation criteria.

(Evaluation criteria)
5: Stainless steel (no coating) equivalent or better metallic feeling 4: Stainless steel (coating thickness 5 μm) equivalent 3: Stainless steel (coating thickness 10 μm) equivalent 2: Stainless steel (painting thickness 30 μm) equivalent 1: Metallic feeling is not felt

(2-4. Corrosion resistance)
A test piece having a width of 70 mm and a length of 150 mm was cut out from the test sample. Then, the edge and the back surface of the test piece were tape-sealed, and a salt spray test (JIS Z 2371) was performed. Then, the white rust occurrence rate of the unsealed portion after 24 hours was visually measured, and the corrosion resistance was evaluated based on the white rust occurrence rate and the following evaluation criteria. The white rust occurrence rate is the area% of the white rust occurrence part with respect to the area of the observation part.

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

(2-5. Processing adhesion)
A test piece having a width of 50 mm and a length of 50 mm was cut out from the test sample. Then, the test piece was bent at 180 °. The bending process was carried out by sandwiching a 0.5 mm spacer between the test piece and the bending machine in an atmosphere of 20 ° C. Then, a tape peeling test was performed on the outside of the bent portion. That is, a commercially available adhesive tape (cellotape manufactured by Nichiban Co., Ltd. (registered trademark)) was attached to the outside of the bent portion, and then peeled off. Then, the peeled adhesive tape was observed with a loupe having a magnification of 10 times, and the area% of the organic resin coating layer adhered to the adhesive tape (the area% of the peeled portion with respect to the total area of the organic resin coating layer of the bent portion) was measured. .. Then, the processing adhesion was evaluated according to the following evaluation criteria. No. 1 having no organic resin coating layer. At 25, this test was not performed. Therefore, No. in Table 8 The processing adhesion of 25'is indicated by "-".

(Evaluation criteria)
5: No peeling is observed in the organic resin coating layer 4: Peeling is observed in a very small part of the organic resin coating layer (area% of peeled portion ≤ 2%)
3: Peeling is observed on some organic resin coating layers (2% <area% of peeled part ≤ 10%)
2: Peeling is observed in the organic resin coating layer (10% <area% of peeled part ≤ 20%)
1: Large peeling is observed in the organic resin coating layer (area% of peeled part> 20%)

(2-6. Consideration)
No. which is an example. At 2'to 6'and 8'to 32', good blackness, hairline appearance, metallic feeling, corrosion resistance, and processing adhesion were obtained. Specifically, the L ^* value was 50 or less, or 40 or less, and the evaluations of hairline appearance, metallic feeling, corrosion resistance, and processing adhesion were almost all 3 or more. No. 1 having an organic resin coating layer containing a black pigment. In 2'to 24', 26', and 28' to 33', the L ^* value was 40 or less.

However, No. 1 in which the average thickness of the oxide layer is 3.0 μm or more. At 33', the metallic feeling and the processing adhesion tended to be slightly lowered. Therefore, it can be seen that the average thickness of the oxide layer is preferably less than 3.0 μm.

In addition, No. 1 in which the average length along the length direction of the recess is less than 1 cm. At 9', the appearance of the hairline and the metallic feeling tended to be slightly deteriorated. Therefore, it can be seen that the average length along the length direction of the recess is preferably 1 cm or more.

In addition, the number of recesses per unit width exceeds 80 lines / cm. At 13', the processing adhesion tended to be slightly lowered. Therefore, it can be seen that the number of recesses per unit width is preferably 80 / cm or less.

In addition, No. 1 in which the average adhesion amount of the zinc-based plating layer ^{is less than 5 g / m 2.} At 15', the hairline appearance and corrosion resistance tended to be slightly deteriorated. Therefore, it can be seen that the average adhesion amount of the zinc-based plating layer ^{is preferably 5 g / m 2 or more.} In addition, No. 1 in which the amount of Ni added to the electrozinc alloy plating layer is less than 5% by mass. At 25', corrosion resistance was slightly reduced. Therefore, it can be seen that the addition amount when the additive element is added is preferably 5% by mass or more.

In addition, No. 1 having no organic resin coating layer. At 25', the corrosion resistance tended to decrease slightly. The L ^* value also exceeded 40. On the other hand, when the organic resin coating layer containing the black pigment is formed, the L ^* value is 40 or less. Therefore, it can be seen that it is preferable to form an organic resin coating layer (particularly an organic resin coating layer containing a black pigment) on the galvanized steel sheet.

In addition, No. 1 in which the amount of the black pigment added to the organic resin coating layer exceeds 5% by mass. In No. 36'and No. 36'containing a black pigment in the lower coating film, the appearance of the hairline tended to be slightly deteriorated. Therefore, it can be seen that it is preferable that the amount of the black pigment added is 5% by mass or less and that the lower coating film does not contain the black pigment. In addition, No. 26', No. The evaluation of the appearance of the hairline of 36'is 2, but it is a level that is not a problem in practical use.

In addition, No. 1 in which a blue pigment was added to the organic resin coating layer. At 27', the L ^* value exceeded 40. Therefore, it can be seen that it is preferable to use a black pigment in order to further reduce the ^{L * value.}

Further, there is no lower layer, that is, the organic resin coating layer containing the black pigment directly covers the surface of the concave portion and the flat portion. At 31', the hairline appearance, metallic feeling, corrosion resistance, and processing adhesion tended to be slightly deteriorated. Therefore, it can be seen that it is preferable that there is a lower layer that does not have a colorant such as a black pigment.

On the other hand, No. In 1', since the oxide layer was completely polished, the hairline appearance, corrosion resistance, and processing adhesion were significantly deteriorated. No. In 7', since the polishing with the polishing brush was not performed (that is, the hairline was not formed), the hairline could not be visually recognized in the first place, and the metallic feeling was significantly reduced. No. At 33', the oxide layer is very thick, and the bottom of the recess does not reach the zinc-based plating layer below the oxide layer. Therefore, SA is 100. Further, the SB in the flat portion is also 100. Therefore, SA / SB greatly exceeds 0.5. And No. At 33', the metallic feeling and the processing adhesion were remarkably lowered.

Although preferred embodiments and examples of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

According to the present invention, even when an inexpensive steel material is used, zinc-based plating has good corrosion resistance, a good hairline appearance, and excellent blackness, metallic feeling, and processing adhesion. It becomes possible to provide a steel plate.

1, 1'Galvanized steel sheet 11, 11'Steel sheet 13, 13' Zinc-based plating layer 14, 14' Oxide layer 15, 15'Organic resin coating layer 101, 101' 105 Recess 103 Non-hairline part 103' Flat part 111 Rough part 113 Smooth part

Claims (29)

Steel plate and
A zinc-based plating layer located on at least one surface of the steel sheet and having a hairline formed as a recess extending in a predetermined direction.
An oxide layer located on the surface of the zinc-based plating layer and having an average thickness of 0.05 μm or more and 3.0 μm or less.
A galvanized steel sheet with. The zinc-based plated steel sheet according to claim 1, wherein the oxide layer is located on the surface of the zinc-based plated layer other than at least the recess. A translucent organic resin coating layer is further provided on the surface of the oxide layer.
The galvanized steel sheet according to claim 1 or 2. The zinc-based plated steel sheet according to any one of claims 1 to 3, wherein the blackness of the surface of the zinc-based plated steel sheet is ^{40 or less in L * value.} The oxide layer is composed of a rough portion and a smooth portion.
The rough portion _{includes a region where the surface roughness Ra A} is more than 500 nm and 5000 nm or less.
The smooth portion includes a region having a surface roughness Ra _B of more than 5 nm and 500 nm or less.
The boundary between the rough portion and the smooth portion of the oxide layer within a range of an observation width of 1 cm along the hairline orthogonal direction in a cross section in the hairline orthogonal direction orthogonal to the predetermined direction and in the plate thickness direction. Assuming that the height is 1/3 of the maximum height Ry obtained by subtracting the minimum point H ₀ from the highest point H _{1 and is on a virtual straight line parallel to the hairline orthogonal direction.}
Said oxide layer boundary is defined between the smooth portion and the coarse portion in plan view, in the same area unit together, the area of the coarse portion and S _A, when the area of the smooth portion and the S _B In addition, the area ratio S _B / S _A is 0.6 or more and 10.0 or less.
The average height difference between the rough portion and the smooth portion adjacent to the rough portion is 0.3 μm or more and 5.0 μm or less.
The galvanized steel sheet according to any one of claims 1 to 4. The total area of the region the surface roughness Ra _A of the rough portion is less than 500nm ultra 5000nm is 85% or more with respect to the area _{S A} of the coarse portion,
The total area of the surface roughness Ra _B is less than 5nm ultra 500nm region of the smooth portion is 65% or more with respect to the area _{S B} of the smoothing part,
The galvanized steel sheet according to claim 5. The rough portion is formed on the hairline,
The average length of the hairline along the stretching direction is 1 cm or more.
The galvanized steel sheet according to claim 5 or 6. The smooth portion is formed on the hairline,
The average length of the hairline along the stretching direction is 1 cm or more.
The galvanized steel sheet according to claim 5 or 6. The hairlines are present in an arbitrary 1 cm width range along the direction orthogonal to the hairlines with an average frequency of 3 lines / cm or more and 80 lines / cm or less.
The galvanized steel sheet according to any one of claims 1 to 8. On the surface of the steel sheet, a recess is formed at a position corresponding to the hairline in the zinc-based plating layer.
The galvanized steel sheet according to any one of claims 1 to 9. The zinc-based plating layer is a zinc-based electroplating layer.
The zinc-based plated steel sheet according to any one of claims 1 to 10, wherein the average adhesion amount of the zinc-based electroplating layer is 5 g / m ² or more and 40 g / m ^{2 or less.} The zinc-based electroplating layer is
Any one or more additive elements selected from the group consisting of Fe, Ni, and Co are added in a total amount of 5% by mass or more and 20% by mass or less.
The balance of Zn and impurities,
Contains,
The zinc-based plated steel sheet according to claim 11. The zinc-based plating layer is a zinc-based hot-dip plating layer.
The average adhesion amount of the zinc-based hot-dip plating layer is ^{more than 40 g / m 2 and} 150 g / m ² or less.
The galvanized steel sheet according to any one of claims 1 to 10. The zinc-based hot-dip plating layer is
Any one or more additive elements selected from the group consisting of Al and Mg are added in a total of 1% by mass or more and 60% by mass or less.
The balance of Zn and impurities,
Contains,
The zinc-based plated steel sheet according to claim 13. The organic resin coating layer has a coloring pigment.
The galvanized steel sheet according to claim 3. On the surface of the oxide layer, the recess and the flat portion which is a region other than the recess are formed.
The average depth of the recess is 0.1 μm or more and less than 3.0 μm.
The bottom of the recess reaches the zinc-based plating layer below the oxide layer and
The ratio AR1 / AR2 of the area ratio AR1 of the oxide layer existing in the concave portion in a plan view to the area ratio AR2 of the oxide layer existing in the flat portion in a plan view is 0 or more and 0.5 or less. Is,
The galvanized steel sheet according to claim 1 or 2. The zinc-based plated steel sheet according to claim 16, wherein the average depth of the recesses is 0.1 μm or more and less than 2.0 μm. The zinc-based plated steel sheet according to claim 17, wherein the zinc-based plating layer is a zinc-based electroplating layer. The zinc-based plated steel sheet according to any one of claims 16 to 18, wherein the oxide layer contains any one or more selected from the group consisting of zinc hydroxide and zinc oxide. The zinc-based plated steel sheet according to any one of claims 16 to 18, wherein the average thickness of the oxide layer is 0.05 μm or more and less than 3.0 μm. Any one of claims 16 to 20, wherein the recess includes a region having a surface roughness RaA'of more than 5 nm and 500 nm or less, and the flat portion includes a region having a surface roughness RaB' of more than 500 nm and 5000 nm or less. The galvanized steel sheet described in the section. The zinc-based plated steel sheet according to any one of claims 16 to 21, wherein the average length along the length direction of the recess is 1 cm or more. 16 to 80. The recesses are present in an arbitrary 1 cm width range along a direction orthogonal to the length direction of the recesses at a frequency of 3 lines / cm or more and 80 lines / cm or less on average. The zinc-based plated steel sheet according to any one of 22. The zinc-based plated steel sheet according to any one of claims 16 to 23, wherein the average adhesion amount of the zinc-based plated layer is 5 g / m ² or more and 40 g / m ^{2 or less.} The zinc according to any one of claims 16 to 24, wherein the oxide layer contains any one or more additive elements selected from the group consisting of Fe, Ni, and Co as the second component. System-plated steel plate. The zinc-based plating layer contains any one or more additive elements selected from the group consisting of Fe, Ni, and Co in a total of 5% by mass or more and 20% by mass or less of these additive elements, and the zinc. The zinc-based plated steel sheet according to any one of claims 16 to 25, wherein the balance of the system-plated layer is Zn and impurities. The zinc-based plated steel sheet according to claim 3, wherein the organic resin coating layer contains a black pigment. The zinc-based plated steel sheet according to claim 27, wherein the organic resin coating layer is two or more layers, and the black pigment is contained in any one or more layers other than the bottom layer. The zinc-based plated steel sheet according to claim 28, wherein the organic resin coating layer further contains any one or more additive elements selected from Si, P, and Zr.

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