CN113825640A

CN113825640A - Plated steel sheet

Info

Publication number: CN113825640A
Application number: CN202080036690.XA
Authority: CN
Inventors: 二叶敬士; 后藤靖人; 柴尾史生; 久米久留巳; 横道拓哉; 宫田卓哉
Original assignee: Nippon Steel and Sumitomo Metal Corp
Current assignee: Nippon Steel Corp
Priority date: 2019-05-24
Filing date: 2020-05-22
Publication date: 2021-12-21
Anticipated expiration: 2040-05-22
Also published as: KR102592017B1; WO2020241475A1; KR20210152501A; CN113825640B

Abstract

A plated steel sheet according to an embodiment of the present invention includes: the galvanized steel sheet has a galvanized layer formed on the surface of the base steel sheet, and a colored resin layer formed on the galvanized layer, wherein a plated texture is formed on the surface of the galvanized layer, the colored resin layer contains a coloring agent, the plated texture comprises a plurality of convex portions and a plurality of concave portions, the three-dimensional average roughness Sas of the bottom of the concave portions is greater than 200nm and less than 2000nm, the DKmin x CK is less than 15.0, and the DKmax-DKmin x CK is greater than 1.0. A plated steel sheet according to another aspect of the present invention includes: the galvanized steel sheet has a texture extending in one direction, and the colored resin layer contains a coloring agent, has a three-dimensional average roughness Saave 'of more than 5nm and 200nm or less, has a DKMin' xCK 'of 15.0 or less, and has a DKMax' -DKMin ') xCK' of more than 1.0.

Description

Plated steel sheet

Technical Field

The present invention relates to a plated steel sheet.

The present application claims priority based on japanese patent application No. 2019-171166 applied in japan on 20/9/2019, japanese patent application No. 2019-171137 applied in japan on 20/9/2019, and japanese patent application No. 2019-098050 applied in japan on 24/5/2019, and the contents thereof are cited.

Background

Articles such as electric appliances, building materials, and vehicles sometimes require design. As a method for improving the design of an article, there are a method of coating the surface of an article and a method of attaching a film.

Recently, materials having a metallic texture tend to be preferred mainly in the european and american worries of chongning nature. If the texture of metal is to be used, a stainless steel plate or an aluminum plate having excellent corrosion resistance even in an uncoated state is used as a material. Further, there are also provided stainless steel plates and aluminum plates on the market which have a texture represented by a hairline formed on the surface thereof for the purpose of further developing the metallic feeling of the stainless steel plates and aluminum plates. However, stainless steel plates and aluminum plates are expensive. Therefore, a low-cost material capable of replacing stainless steel plates and aluminum plates is required.

As an alternative material to such a stainless steel sheet or aluminum sheet, a plated steel sheet having a zinc plating layer on the surface thereof has been studied. In this specification, the zinc-plated layer also includes a zinc-alloy plated layer. The plated steel sheet has appropriate corrosion resistance and excellent workability, as with a stainless steel sheet and an aluminum sheet. Therefore, the plated steel sheet is suitable for use in electric appliances, building materials, and the like. Therefore, various proposals have been made in the industry for the purpose of improving the design of the plated steel sheet.

For example, japanese patent application laid-open No. 2006-124824 (patent document 1) discloses the following: after the galvanized steel sheet is subjected to a hairline finish, a transparent resin film is formed on the surface of the galvanized layer on which the hairline is formed. Thus, the surface of the plating layer can be visually confirmed while maintaining the corrosion resistance, and the design is improved.

In addition, the following is disclosed in japanese patent publication No. 2013-536901 (patent document 2): after the galvanized steel sheet is rolled to form a texture on the surface of the galvanized layer, the surface of the galvanized layer is coated with an organic film (resin) having a surface roughness within a certain range. Thereby, the surface of the plating layer can be visually confirmed while maintaining the corrosion resistance, and the design is improved.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2006-124824

Patent document 2: japanese Kohyo publication No. 2013-536901

Disclosure of Invention

Technical problem to be solved by the invention

Recently, materials having a colored appearance while utilizing the metallic texture have been desired. More specifically, there is a need for a plated steel sheet that has a colored appearance and in which the texture of the surface of the zinc-plated layer can be visually confirmed.

The invention aims to: provided is a plated steel sheet which has a colored appearance and in which the texture of the surface of a zinc-plated layer can be visually confirmed.

Means for solving the problems

(1) A plated steel sheet according to an aspect of the present invention includes:

a base steel plate having a base texture on the surface,

A zinc-plated layer formed on the surface of the base material steel sheet having the base material texture, and a colored resin layer formed on the zinc-plated layer,

the zinc plating layer has a plating texture on the surface thereof,

the colored resin layer contains a coloring agent,

the plating texture includes a plurality of protrusions and a plurality of recesses,

when the rolling direction of the base steel sheet is defined as a1 st direction, and a direction perpendicular to the 1 st direction on the surface of the plated steel sheet is defined as a 2 nd direction, the plated steel sheet satisfies the following (a) to (C):

(A) measuring a roughness profile of the plating texture within a range of 1000 μm in length in the 2 nd direction, specifying 10 recess bottom points in the plurality of recess bottom points of the roughness profile in order from the lowest when the lowest position in each of the recesses in the measured roughness profile is defined as a recess bottom point, measuring a three-dimensional average roughness Sa of a fine region of 1 μm × 1 μm centered on the specified recess bottom point, and defining an arithmetic average of the 10 measured three-dimensional average roughnesses Sa as a recess bottom three-dimensional average roughness Sas, wherein the recess bottom three-dimensional average roughness Sas is greater than 200nm and 2000nm or less,

(B) in the range of 100 μm in the 2 nd direction length, the minimum thickness (μm) of the colored resin layer is defined as DKmin, the content (% by area) of the colorant in the colored resin layer is defined as CK, and when F1 is defined by formula (1), the F1 is 15.0 or less,

F1＝DKmin×CK (1)

(C) in the range of 100 μm in the 2 nd direction, the maximum thickness (μm) of the colored resin layer is defined as DKmax, and when F2 is defined by formula (2), the F2 is greater than 1.0

F2＝(DKmax-DKmin)×CK (2)。

(2) The plated steel sheet according to the item (1), which may further satisfy the following (D):

(D) and measuring a roughness profile having a length in the 2 nd direction of the plating texture within a range of 1000 μm, wherein when a highest position of each of the convex portions in the measured roughness profile is defined as a convex portion apex, 10 convex portion apexes are specified in order from the highest position among the plurality of convex portion apexes of the roughness profile, a three-dimensional average roughness Sa of a minute region of 1 μm × 1 μm centered on the specified convex portion apex is measured, and an arithmetic average of the 10 measured three-dimensional average roughnesses Sa is defined as a convex portion top three-dimensional average roughness Sas, and the convex portion top three-dimensional average roughness Sah is greater than 5nm and 200nm or less.

(3) The plated steel sheet according to item (2), wherein,

a plurality of the convex portions and a plurality of the concave portions may extend in the 1 st direction,

the plurality of convex portions and the plurality of concave portions may be aligned in the 2 nd direction.

(4) The plated steel sheet according to item (3), wherein,

the texture of the parent material can be hair lines,

the plated texture may be a hair line,

the plated steel sheet may further satisfy the following (E) and (F):

(E) wherein Ra (Ra) (CL) represents the surface roughness Ra of the colored resin layer in the 1 st direction, Ra (CC) represents the surface roughness Ra of the colored resin layer in the 2 nd direction, and F3 is defined by formula (3), wherein F3 is 1.10 or more,

F3＝Ra(CC)/Ra(CL) (3)

(F) when the surface roughness of the zinc plating layer in the 2 nd direction is defined as Ra (MC), Ra (MC) is 0.30 μm or more.

(5) The plated steel sheet according to any one of claims (1) to (4),

lightness L when the plated steel sheet is observed from the side of the colored resin layer^*The (SCI) may be 45 or less.

(6) The plated steel sheet according to any one of claims (1) to (5),

f1 may be 13.5 or less.

(7) The plated steel sheet according to any one of claims (1) to (6),

f2 may be greater than 2.0.

(8) The plated steel sheet according to any one of claims (4) to (7),

the F3 may be 1.15 or more.

(9) The plated steel sheet according to any one of claims (1) to (8),

the galvanized layer may have an exposure of the base steel sheet of less than 5%.

(10) The plated steel sheet according to item (2), wherein,

the plurality of protrusions may be formed by grinding the surface of the zinc plating layer,

a plurality of the recesses may be unground.

(11) A plated steel sheet according to another aspect of the present invention includes:

a base steel plate,

A zinc-plated layer formed on the surface of the base steel sheet, and

a colored resin layer formed on the zinc-plated layer, wherein,

the zinc plating layer has a texture extending in one direction on the surface thereof,

the colored resin layer contains a coloring agent,

the plated steel sheet satisfies the following requirements (A ') to (C'):

(a ') measuring a roughness profile having a length in a range of 1000 μm in a direction perpendicular to an extending direction of the texture, wherein 10 positions specified in order from a low height among the positions on the measured roughness profile are defined as valley bottom points, 10 positions specified in order from a high height among the positions on the measured roughness profile are defined as peak points of the protrusions, and a three-dimensional average roughness Sa ' of a minute region of 1 μm × 1 μm centered around each valley bottom point and each peak point of the protrusions is measured, and when an arithmetic average of the measured three-dimensional average Sa ' roughness is defined as a three-dimensional average roughness Saave ', the three-dimensional average roughness Saave ' is greater than 5nm and 200nm or less;

(B ') in the range of 100 μm in length in the direction perpendicular to the extending direction of the grain, the minimum thickness (μm) of the colored resin layer is defined as DKMin', and when the content (% by area) of the colorant in the colored resin layer is defined as CK ', formula (1') is satisfied,

DKmin’×CK’≤15.0 (1’)；

(C ') satisfying the formula (2 ') in a range where the length in the direction perpendicular to the extending direction of the grain is 100 μm and the maximum thickness (μm) of the colored resin layer is defined as DKmax ',

(DKmax’-DKmin’)×CK’>1.0 (2’)。

(12) the plated steel sheet according to item (11), wherein,

the texture may be a hair line or a hairline,

the plated steel sheet may satisfy the following (D ') and (E'):

(D ') when the surface roughness Ra of the colored resin layer in the extending direction of the grain is defined as Ra (CL)', and the surface roughness Ra of the colored resin layer in the direction perpendicular to the extending direction of the grain is defined as Ra (CC) ', formula (3') is satisfied,

Ra(CC)’≥Ra(CL)’×1.10 (3’)；

(E ') Ra (MC) ' is 0.30 μm or more when the surface roughness of the zinc plating layer in the direction perpendicular to the extending direction of the texture is defined as Ra (MC) '.

(13) The plated steel sheet according to the item (11) or (12), wherein,

(14) The plated steel sheet according to any one of claims (1) to (13),

the colored resin layer may be a laminated resin layer,

the laminated resin layer may include a plurality of colored resin layers laminated in a direction normal to the surface of the base steel sheet,

in the plurality of colored resin layers, a sum of products of a content (area%) of the colorant in the colored resin layer and a thickness (μm) of the colored resin layer may be 15.0 area% · μm or less,

among the plurality of colored resin layers, when a colored resin layer having a largest product of a content (area%) of the colorant in the colored resin layer and a thickness (μm) of the colored resin layer is defined as a most dense colored resin layer, and a colored resin layer having a largest product 2 of the content of the colorant in the colored resin layer and the thickness of the colored resin layer is defined as a 2 nd dense colored resin layer, a content C of the colorant in the most dense colored resin layer_1ST(area%), thickness D of the densest colored resin layer_1ST(μm), content C of the colorant of the 2 nd color-dense colored resin layer_2ND(area%) and thickness D of the 2 nd color-colored resin layer_2ND(. mu.m) may satisfy formula (4),

1.00<(C_1ST×D_1ST)/(C_2ND×D_2ND)≤4.00 (4)。

(15) the plated steel sheet according to item (14), wherein,

the thickness of the laminated resin layer may be 10.0 μm or less.

(16) The plated steel sheet according to the item (14) or (15), wherein,

the laminated resin layer may further comprise 1 or more transparent resin layers not containing the colorant,

the laminated resin layer may be formed by laminating the plurality of colored resin layers and the 1 or more transparent resin layers.

ADVANTAGEOUS EFFECTS OF INVENTION

The plated steel sheet according to the present invention has a colored appearance and the texture of the surface of the galvanized layer can be visually confirmed.

Drawings

Fig. 1 is a schematic view of a cross section perpendicular to the 1 st direction in a plated steel sheet according to embodiment 1.

Fig. 2 is a cross-sectional view of a plated steel sheet according to embodiment 1.

FIG. 3 is an enlarged view of the colored resin layer shown in FIG. 2.

Fig. 4 is a plan view of a zinc plating layer having hairlines formed as textures on the surface.

Fig. 5 is a diagram showing a roughness profile of a plating texture formed on the surface of a zinc plating layer.

Fig. 6A is a schematic view for explaining a minute concave bottom region in the surface of a galvanized layer.

Fig. 6B is a schematic view for explaining a minute convex top region in the surface of the galvanized layer.

Fig. 7 is a sectional view perpendicular to the 1 st direction at a portion near the surface of the galvanized layer.

Fig. 8 is a sectional view perpendicular to the 1 st direction at a portion near the surface of the galvanized layer of embodiment 1.

Fig. 9 is a schematic view of a cross section perpendicular to the extending direction of the grain in the plated steel sheet according to embodiment 2.

Fig. 10 is a cross-sectional view of a plated steel sheet according to embodiment 2.

Fig. 11 is an enlarged view of the colored resin layer shown in fig. 10.

Fig. 12 is a plan view of a zinc plating layer having hairlines formed as textures on the surface.

Fig. 13 is a view showing a roughness profile of a texture formed on a surface of a galvanized layer.

Fig. 14A is a schematic view for explaining a minute recessed region in the surface of a galvanized layer.

Fig. 14B is a schematic view for explaining a minute convex portion region in the surface of the galvanized layer.

Fig. 15A is a schematic view of the cut section CS.

Fig. 15B is a schematic view of the cut section CS.

FIG. 16 is a view for explaining: a schematic diagram of a method for evaluating color unevenness when the surface of the zinc coating layer of the design galvanized steel sheet according to the present embodiment has hairlines as texture.

FIG. 17 is a view for explaining: a schematic diagram of a method for evaluating color fluctuation when the surface of the zinc coating layer of the design galvanized steel sheet of the present embodiment has hairlines as texture.

Detailed description of the invention

(embodiment 1)

The present inventors have studied a plated steel sheet having a colored appearance and a texture on the surface of a zinc-plated layer (hereinafter referred to as a plating texture) that can be visually confirmed. As described in

patent documents

1 and 2, a galvanized steel sheet having a transparent resin layer formed on a galvanized layer has been proposed. Therefore, the present inventors have first tried to manufacture a galvanized steel sheet colored by including a colorant containing a pigment and/or a dye in a resin layer formed on a galvanized layer.

As a result, it was found that when a coloring agent was contained in the resin layer, the plating texture formed on the surface of the galvanized layer could not be visually confirmed depending on the conditions. Therefore, the present inventors have investigated and studied factors that affect visual confirmation of plating texture when a colorant is contained in a resin. As a result, the present inventors have obtained the following findings. In the following description, the rolling direction of the base steel sheet is defined as the 1 st direction RD. In addition, in the surface of the plated steel sheet, a direction perpendicular to the 1 st direction (the width direction of the plated steel sheet) is defined as a 2 nd direction WD. A direction (thickness direction of the plated steel plate) perpendicular to the 1 st direction RD and the 2 nd direction WD is defined as a 3 RD direction TD.

When a colored resin layer containing a coloring agent is formed on a galvanized layer having a plating texture formed on the surface thereof, the content of the coloring agent in the colored resin layer and the thickness of the colored resin layer affect visual confirmation of the plating texture. Specifically, if the content of the colorant in the colored resin layer is too large, the plating texture may not be visually confirmed. Also, if the colored resin layer is too thick, the plating texture may not be visually confirmed.

In addition, in a cross section perpendicular to the 1 st direction RD, the thickness of the resin formed on the plating texture varies depending on the unevenness of the plating texture. Fig. 1 is a schematic view of a cross section perpendicular to the 1 st direction RD of a plated steel sheet according to embodiment 1. Referring to fig. 1, a plated steel sheet 1 includes a base steel sheet 100, a galvanized layer 10, and a colored resin layer 11. The base steel sheet 100 has a texture 100S on its surface. Hereinafter, the texture 100S is referred to as a base material texture 100S. The galvanized layer 10 has a plating texture 10S on its surface. The plating texture 10S includes a plurality of protrusions 10co (convex) and a plurality of recesses 10re (processes). The convex portions 10CO and the concave portions 10RE are alternately arranged. In fig. 1, the plurality of convex portions 10CO and the plurality of concave portions 10RE are alternately arranged in the 2 nd direction WD.

The colored resin layer 11 is formed on the surface of the galvanized layer 10. Therefore, the surface 11S of the colored resin layer 11 reflects the concave-convex pattern (the shapes of the concave portion 10RE and the convex portion 10 CO) of the plated texture 10S to some extent, but is more flattened than the plated texture 10S. Specifically, in the surface 11S of the colored resin layer 11, the convex portions 11CO are formed at portions corresponding to the convex portions 10CO of the plating texture 10S. The height of the convex portion 11CO is lower than the height of the convex portion 10 CO. That is, the surface 11S of the colored resin layer 11 is more planarized than the surface of the plating texture 10S.

Here, in the range of 100 μm in length in the 2 nd direction WD, the maximum thickness (μm) of the colored resin layer 11 is defined as DKmax. Further, the minimum thickness (μm) of the colored resin layer 11 is defined as DKmin. In order to make the plated texture 10S visually recognizable even when colored by the colored resin layer 11, as described above, the content CK (area%) of the coloring agent in the colored resin layer 11 and the thickness of the colored resin layer 11 need to be limited to some extent. Also, under the limitation thereof, the difference between the maximum thickness DKmax and the minimum thickness DKmin of the colored resin layer 11 is reflected in the lightness difference that the plating texture can be visually confirmed. Specifically, by making the difference between the maximum thickness DKma x and the minimum thickness DKmin of the colored resin layer 11 large to a certain extent, the concave portions 10RE and the convex portions 10CO of the plated texture 10S are different in lightness. As a result, even when the colored resin layer 11 is formed, the plated texture 10S can be visually recognized.

Further, the colored resin layer 11 preferably has high adhesion to the galvanized layer 10. Therefore, the present inventors have studied a method for improving the adhesion of the colored resin layer 11 to the galvanized layer 10. As a result, it was found that: by roughening the surface roughness of the convex portions 10CO and the concave portions 10RE of the plating texture 10S, particularly, in the fine regions of the concave portions 10RE to a certain extent (specifically, by making the three-dimensional average roughness Sas of the bottom portions of the concave portions, which will be described later, greater than 200nm and 2000nm or less), the adhesion of the colored resin layer 11 to the galvanized layer 10 can be improved.

Based on the above findings, the present inventors have found that a plated steel sheet having a colored appearance, a plating texture on the surface of a galvanized layer being visually recognized, and excellent adhesion of a colored resin layer can be obtained by the following (a) to (C): (A) the surface roughness of the fine region in the recessed portion 10RE of the convex portion 10CO and the recessed portion 10RE of the plating texture 10S is roughened to a certain degree, (B) the thickness and the colorant content of the colored resin layer 11 are adjusted, and (C) the difference between the maximum thickness DKmax and the minimum thickness DKmin of the colored resin layer 11 in the cross section perpendicular to the 1 st direction is adjusted to a certain degree.

The plated steel sheet according to embodiment 1 completed based on the above findings has the following configuration:

[1] the plated steel sheet of (1) comprises:

a base steel plate having a base texture on the surface,

the zinc plating layer has a plating texture on the surface thereof,

the colored resin layer contains a coloring agent,

when the rolling direction of the base steel sheet is defined as a1 st direction and a direction perpendicular to the 1 st direction is defined as a 2 nd direction, the plated steel sheet satisfies the following (a) to (C):

(A) and measuring a roughness profile of the plating texture within a range of a length of 1000 μm in the 2 nd direction, wherein when a lowest position of each of the recesses in the measured roughness profile is defined as a recess bottom point, 10 recess bottom points are specified in order from the lowest among the plurality of recess bottom points of the roughness profile, a three-dimensional average roughness Sa of a minute region of 1 μm × 1 μm centered on the specified recess bottom point is measured, and an arithmetic average of the 10 measured three-dimensional average roughnesses Sa is defined as a recess bottom three-dimensional average roughness Sas, the recess bottom three-dimensional average roughness Sas is greater than 200nm and 2000nm or less.

(B) In the range of 100 μm in the 2 nd direction length, the minimum thickness (μm) of the colored resin layer is defined as DKmin, the content (area%) of the colorant in the colored resin layer is defined as CK, and when F1 is defined by formula (1), the F1 is 15.0 or less.

F1＝DKmin×CK (1)

(C) In the range of 100 μm in the 2 nd direction length, the maximum thickness (μm) of the colored resin layer is defined as DKmax, and when F2 is defined by formula (2), the F2 is greater than 1.0.

F2＝(DKmax-DKmin)×CK (2)

[2] The plated steel sheet according to [1], which further satisfies the following (D):

The roughness of the plated texture can have an effect on the visual confirmation of the plated texture. When the plating texture is formed on the surface of the zinc plating layer, not only the unevenness of the plating texture but also minute unevenness (roughness) due to the crystals of the zinc plating exist on the surface of the plating texture. If the fine irregularities caused by the crystals of the zinc plating are small, the diffuse reflection of light due to the fine irregularities caused by the crystals of the zinc plating is suppressed. In this case, the gloss of the plating texture is improved, and the whitening of the plating texture is suppressed. In the plated steel sheet according to [2], the roughness in the microscopic region of the concave portion in the plating texture is maintained at 200nm or more, and the roughness in the microscopic region of the convex portion is suppressed to 200nm or less. Therefore, the adhesion of the colored resin layer is maintained by the concave portions of the plating texture, and the visibility of the plating texture can be further improved by the convex portions.

[3] The plated steel sheet according to [2], wherein,

[4] The plated steel sheet according to [3], wherein,

the texture of the parent material can be hair lines,

the plated texture may be a hair line,

the plated steel sheet may further satisfy the following (E) and (F):

(E) when the surface roughness Ra of the colored resin layer in the 1 st direction is defined as Ra (cl), the surface roughness Ra of the colored resin layer in the 2 nd direction is defined as Ra (cc), and F3 is defined by formula (3), the F3 is 1.10 or more.

F3＝Ra(CC)/Ra(CL) (3)

[5] The plated steel sheet according to any one of [1] to [4], wherein,

[6] The plated steel sheet according to any one of [1] to [5], wherein,

f1 may be 13.5 or less.

[7] The plated steel sheet according to any one of [1] to [6], wherein,

f2 may be greater than 2.0.

[8] The plated steel sheet according to any one of [4] to [7], wherein,

the F3 may be 1.15 or more.

[9] The plated steel sheet according to any one of [1] to [8], wherein,

[10] The plated steel sheet according to [2], wherein,

a plurality of the protrusions may be formed by grinding the surface of the zinc plating layer,

a plurality of the recesses may be unground.

Hereinafter, the plated steel sheet of embodiment 1 will be described in detail.

[ plated steel sheet 1]

Fig. 2 is a sectional view of the plated steel sheet 1 according to embodiment 1. Referring to fig. 2, a plated steel sheet 1 according to embodiment 1 includes: base steel sheet 100, galvanized layer 10, and colored resin layer 11. The galvanized layer 10 is formed on the base material grain 100S of the surface of the base material steel sheet 100. The colored resin layer 11 is formed on the surface (texture) 10S of the galvanized layer 10. The galvanized layer 10 is disposed between the base steel sheet 100 and the colored resin layer 11. Hereinafter, the base steel sheet 100, the galvanized layer 10, and the colored resin layer 11 will be described.

[ base Steel sheet 100]

The base steel sheet 100 may be a known steel sheet that can be applied to a plated steel sheet, depending on various mechanical properties (for example, tensile strength, workability, and the like) required for the plated steel sheet to be produced. For example, as the base steel sheet 100, a steel sheet for electric appliance use may be used, and a steel sheet for vehicle outer panel use may be used. Base steel sheet 100 may be a hot-rolled steel sheet or a cold-rolled steel sheet.

The surface of the base steel plate 100 has a texture 100S (base texture 100S). That is, the base steel sheet 100 has a texture 100S (base texture 100S) on its surface. The plating texture 10S described later can be formed along the base texture 100S. In this case, the pattern of the plating texture 10S is similar to the pattern of the base material texture 100S. For example, when the base material texture 100S is dull, the plating texture 10S is also dull. When the base material texture 100S is a hairline, the plating texture 10S is also a hairline. On the other hand, the base material texture 100S may have a pattern different from the plating texture 10S. For example, the base material texture 100S may be a matte texture and the plating texture 10S may be a hairline texture.

[ with respect to the galvanized layer 10]

The galvanized layer 10 is formed on the surface of the base steel sheet 100. In embodiment 1, the galvanized layer 10 is disposed between the base steel sheet 100 and the colored resin layer 11. The galvanized layer 10 is formed by a known galvanizing method. Specifically, the galvanized layer 10 is formed by, for example, an electroplating method. In this specification, the zinc-plated layer 10 also includes a zinc-alloy plated layer.

The galvanized layer 10 may have a well-known chemical composition. For example, the Zn content in the chemical composition of the galvanized layer 10 may be 65% by mass or more. If the Zn content is 65% by mass or more, the sacrificial corrosion prevention function can be remarkably exhibited, and the corrosion resistance of the plated steel sheet 1 is remarkably improved. The preferable lower limit of the Zn content in the chemical composition of the galvanized layer 10 is 70%, and more preferably 80%.

The chemical composition of the galvanized layer 10 preferably contains 1 element or 2 or more elements selected from Al, Co, Cr, Cu, Fe, Ni, P, Si, Sn, Mg, Mn, Mo, V, W, and Zr in addition to Zn. Further, the chemical composition when the galvanized layer 10 is a zinc plating layer further preferably contains at least 1 element selected from Fe, Ni, and Co in a total amount of 5 to 20 mass%. Further, the chemical composition when the galvanized layer 10 is a hot-dip galvanized layer further preferably contains at least 1 or more elements selected from Mg, Al, and Si in a total amount of 5 to 20 mass%. In these cases above, the galvanized layer 10 further exhibits excellent corrosion resistance.

The galvanized layer 10 may contain impurities. Here, the impurities mean impurities mixed in the raw materials or impurities mixed in the production process. The impurities include, for example, Ti, B, S, N, C, Nb, Pb, Cd, Ca, Pb, Y, La, Ce, Sr, Sb, O, F, Cl, Zr, Ag, W, H, etc. The galvanized layer 10 preferably has a chemical composition in which the total content of impurities is 1% or less.

As for the chemical composition of the galvanized layer 10, for example, it can be measured by the following method: the colored resin layer 11 of the plated steel sheet 1 is removed with a solvent or a remover (for example, a product name: Neo revert S-701 manufactured by tricolor chemical) which does not attack the galvanized layer 10. Then, the galvanized layer 10 is dissolved using hydrochloric acid to which an inhibitor is added. The dissolved solution was subjected to ICP (Inductively Coupled Plasma) analysis using an ICP emission spectrometer to determine the Zn content. If the obtained Zn content is 65% or more, it is judged that the plating layer to be measured is the zinc plating layer 10.

[ amount of adhesion to the galvanized layer 10]

The amount of adhesion of the galvanized layer 10 is not particularly limited, and a known amount of adhesion is sufficient. The preferable adhesion amount of the zinc-plated layer 10 is 5.0 to 120.0g/m². If the adhesion amount of the zinc plating layer 10 is 5.0g/m²In the above case, when a plating texture described later is given to the galvanized layer 10,exposure of the base steel plate (base steel plate 100) can be suppressed. A more preferable lower limit of the adhesion amount of the galvanized layer 10 is 7.0g/m²More preferably 10.0g/m². The upper limit of the adhesion amount of the galvanized layer 10 is not particularly limited. From the viewpoint of economy, in the case of the galvanized layer 10 formed by the electroplating method, the upper limit of the adhesion amount is preferably 40.0gm²More preferably, the upper limit is 35.0g/m²More preferably 30.0g/m²。

[ colored resin layer 11]

The colored resin layer 11 is formed on the surface (plating texture) 10S of the galvanized layer 10. Fig. 3 is an enlarged view of the colored resin layer 11 shown in fig. 2. Referring to fig. 3, colored resin layer 11 includes resin 31 and colorant 32. The colorant 32 is contained in the resin 31. The resin 31 and the colorant 32 will be described below.

[ with respect to resin 31]

The resin 31 is a resin having light transmittance. In embodiment 1, "a resin having light transmittance" means that when the plated steel sheet 1 provided with the colored resin layer 11 containing the colorant 32 and the resin 31 is placed in an environment corresponding to sunlight on the noon of a clear day (illuminance of about 65000 lux), the plating texture 10S of the galvanized layer 10 can be visually confirmed. The resin 31 functions as a binder for fixing the colorant 32.

The resin 31 is not particularly limited as long as it has the light-transmitting property defined above, and a known natural resin or a known synthetic resin can be used. The resin 31 may be 1 or 2 or more selected from among epoxy resins, urethane resins, polyester resins, phenol resins, polyethersulfone resins, melamine alkyd resins, acrylic resins, polyamide resins, polyimide resins, polysiloxane resins, polyvinyl acetate resins, polyolefin resins, polystyrene resins, vinyl chloride resins, and vinyl acetate resins, for example.

[ with respect to the colorant 32]

The coloring agent 32 colors the colored resin layer 11 by being contained in the resin 31. The colorant 32 is a well-known colorant. The colorant 32 has a color. Chromatic refers to a color having attributes of hue, lightness, and chroma. The colorant 32 contains, for example, 1 or more selected from inorganic pigments, organic pigments, and dyes. The colorant 32 is more preferably a pigment (inorganic pigment and/or organic pigment) from the viewpoint of durability against ultraviolet rays.

If the colorant 32 is an inorganic pigment, the colorant 32 is, for example, a neutralized precipitated pigment (sulfate, carbonate, etc.) and/or a fired pigment (metal sulfide, metal oxide, polyvalent metal composite oxide, etc.). If the colorant 32 is an organic pigment, the colorant 32 is, for example, 1 or more selected from chlorine pigments, azo pigments (dissolving azo lake pigments, insoluble azo pigments, etc.), acid condensation pigments, polycyclic pigments (phthalocyanine pigments, indigo pigments, quinacridone pigments, anthraquinone pigments, etc.), and metal complex pigments (azo chelate pigments, transition metal complex pigments, etc.). If the colorant 32 is a dye, the colorant 32 is, for example, 1 or more selected from azo dyes, indigo dyes, anthraquinone dyes, sulfur dyes, and Carbonium dyes (Carbonium dyes).

The color of the colorant 32 is not particularly limited. The colorant 32 is, for example, carbon black (C) or iron black (Fe)₃O₄) And so on to black. However, the colorant 32 is not limited to black, and may be a colorant 32 of another color (white, magenta, yellow, greenblue, red, orange, yellow, green, cyan, blue, violet, etc.).

When the colorant 32 is a pigment, the particle diameter is not particularly limited. When the colorant 32 is a pigment, the maximum value of the primary particle diameter is, for example, 3nm to 1000 nm.

[ concerning the plating texture 10S formed on the surface of the galvanized layer 10]

The galvanized layer 10 of the plated steel sheet 1 has a plating texture 10S formed on the surface thereof. That is, the galvanized layer 10 of the plated steel sheet 1 has a plating texture 10S on the surface thereof. In embodiment 1, "texture" refers to an uneven pattern formed on the surface of the base steel sheet 100 and/or the surface of the galvanized layer 10 by a physical or chemical method. That is, the texture (the base material texture 100S, the plating texture 10S) has a plurality of protrusions and a plurality of recesses. The convex portion and the concave portion may or may not extend in one direction. The texture is, for example, a matte or hairline texture. Preferably the texture is hair lines. The hairline is a linear uneven pattern extending in one direction.

[ case where the plating texture 10S is a hairline ]

Fig. 4 is a plan view of the galvanized layer 10 having hairlines formed on the surface as the plating texture 10S. Referring to fig. 4, the hairline 10S is a linear uneven pattern formed on the surface of the galvanized layer 10. The hairline 10S includes a plurality of grooves 10L extending in the 1 st direction. The plurality of grooves 10L of the hairline 10S extend in substantially the same direction. The substantially same direction as used herein means that 90% or more of the angles formed by the mutually adjacent grooves 10L aligned in the 2 nd direction WD perpendicular to the extending direction of the grooves 10L of the hairline 10S are smaller than ± 5 ° when the galvanized layer 10 is viewed from the thickness direction TD (i.e., as viewed in plan view in fig. 4).

[ concerning the essential items (A) to (C) ]

The plated steel sheet 1 according to embodiment 1 having the above-described configuration further satisfies the following requirements (a) to (C).

Requirement (A):

a roughness profile in the range of 1000[ mu ] m in length in the 2 nd direction WD of the plated texture 10S is measured, the lowest position of each recess 10RE in the measured roughness profile is defined as a recess bottom point, 10 recess bottom points are specified in order from the lowest among a plurality of recess bottom points of the roughness profile, the three-dimensional average roughness Sa of a minute region of 1[ mu ] m × 1[ mu ] m centered on the specified recess bottom point is measured, and the arithmetic average of the 10 measured three-dimensional average roughness Sa is defined as the recess bottom three-dimensional average roughness Sas, and the recess bottom three-dimensional average roughness Sas is greater than 200nm and 2000nm or less.

Requirement (B):

in the range of 100 μm in length in the 2 nd direction WD, the minimum thickness (μm) of the colored resin layer 11 is defined as DKmin, the content (area%) of the colorant 32 in the colored resin layer 11 is defined as CK, and when F1 is defined by formula (1), F1 is 15.0 or less.

F1＝DKmin×CK (1)

Requirement (C):

in the range of 100 μm in length in the 2 nd direction WD, F2 is greater than 1.0 when DKmax is defined as the maximum thickness (μm) of the colored resin layer 11 and F2 is defined by formula (2).

F2＝(DKmax-DKmin)×CK (2)

Hereinafter, each requirement will be described in detail.

[ surface roughness of unevenness of texture ]

Fig. 5 is a diagram showing the roughness profile of the plating texture 10S formed on the surface of the galvanized layer 10. Referring to fig. 5, an arbitrary range having a length of 1000 μm is selected in the 2 nd direction WD of the plated texture 10S. The roughness profile of the plated texture 10S was measured in a selected range of 1000 μm in length. The resulting roughness profile is assumed to be in the shape of fig. 5.

[ three-dimensional average roughness Sas of dent bottom ]

Attention is paid to each concave portion 10RE in the roughness profile obtained by the measurement. In each recess 10RE, the position with the lowest height is defined as a recess bottom point PRE. Among a plurality of recess bottom points PRE in the roughness profile having a length in the range of 1000 μm, 10 recess bottom points PRE1, PRE2, …, PRE10 are designated in order from the lowest recess bottom point PRE1, in descending order.

As shown in FIG. 6A, a minute recessed portion bottom region 200 of 1 μm × 1 μm centered on each of the defined recessed portion bottom points PREk (k is 1 to 10) is specified in a plan view of the surface of the galvanized layer 10. In fig. 6A, the longitudinal direction of the fine recessed portion bottom region 200 is parallel to the extending direction RD of the plated texture 10S, and the lateral direction of the fine recessed portion bottom region 200 is parallel to the width direction WD. However, each side of the fine recessed portion bottom region 200 may not be parallel to the extending direction RD or the width direction WD, as long as the fine recessed portion bottom region 200 includes a plane including the extending direction RD and the width direction WD.

In each of the 10 minute recessed portion bottom regions 200 specified in the above method, the three-dimensional average roughness Sa was measured. The three-dimensional average roughness Sa is an arithmetic average roughness specified in ISO 25178, obtained by expanding Ra (linear arithmetic average roughness) specified in JIS B0601(2013) into a surface. The arithmetic average of the 10 measured three-dimensional average roughness Sa was defined as the three-dimensional average roughness Sa of the bottom of the dent.

[ three-dimensional average roughness Sah of convex portion top ]

Referring to fig. 5, attention is paid to each convex portion 10CO in the roughness profile of the plating texture 10S in the 2 nd direction WD, the arbitrary length being in the range of 1000 μm. In each convex portion 10CO, the position having the highest height is defined as a convex portion apex PCO. Among the plurality of projection apexes PCO in the roughness profile having a length in the range of 1000 μm, 10 projection apexes PCO1, PCO2, …, PCO10 are designated in order from the highest projection apex PCO1 in the order from the highest to the lowest.

As shown in FIG. 6B, in a plan view of the surface of the galvanized layer 10, a fine projection top region 300 of 1 μm × 1 μm centered on each of the defined projection tops PCOk (k is 1 to 10) is specified. In fig. 6B, the longitudinal direction of the fine protrusion top region 300 is parallel to the extending direction RD of the plated texture 10S, and the lateral direction of the fine protrusion top region 300 is parallel to the width direction WD. However, as long as the fine protrusion top region 300 is a plane including the extending direction RD and the width direction WD, each side of the fine protrusion top region 300 may not be parallel to the extending direction RD or the width direction WD.

In each of the 10 minute-protrusion top regions 300 specified in the above method, the three-dimensional average roughness Sa was measured. The three-dimensional average roughness Sa is an arithmetic average roughness specified in ISO 25178, obtained by expanding Ra (linear arithmetic average roughness) specified in JIS B0601(2013) into a surface. The arithmetic average of the 10 measured three-dimensional average roughness Sa was defined as the three-dimensional average roughness Sah of the top of the convex portion.

[ concerning the essential component (A) ]

The three-dimensional average roughness Sas of the bottom of the concave portion determined by the above definition is more than 200nm and 2000nm or less (requirement (a)). The roughness may be considered to be based on crystals of the galvanization. Thus, the galvanized plurality of recesses may not be ground. In the unevenness of the plating texture 10S, the three-dimensional average roughness Sas of the bottom of the recessed portion is rough at least to some extent, and if it is more than 200nm and 2000nm or less, the adhesion of the colored resin layer 11 to the galvanized layer 10 can be improved. The lower limit of the three-dimensional average roughness Sas of the bottom of the recess is preferably 250nm, and more preferably 300 nm. The upper limit of the three-dimensional average roughness Sas of the bottom of the recessed portion is preferably 1500nm, more preferably 1000nm, and still more preferably 800 nm.

In the plated texture 10S, if at least the three-dimensional average roughness Sas of the bottom of the recessed portion is more than 200nm and 2000nm or less, the value of the three-dimensional average roughness Sah of the top of the raised portion is not particularly limited. The three-dimensional average roughness Sah of the top of the projection is, for example, 2000nm or less. Since Sah is infinite, the plurality of convex portions may be formed by grinding the surface of the zinc plating layer or may not be ground. The shape of the irregularities of the plated texture 10S is also not particularly limited.

Fig. 7 is a sectional view perpendicular to the 1 st direction RD at a portion near the surface of the galvanized layer 10. Referring to fig. 7, in the concave portions 10RE and the convex portions 10CO of the plating texture 10S formed on the surface of the galvanized layer 10, before polishing, fine irregularities (fine concave portions SRE and fine convex portions SCO) of nanometer order due to plating crystals are present on the surface of the concave portions 10RE and the surface of the convex portions 10 CO. In this case, the three-dimensional average roughness Sas of the bottom of the concave portion and the three-dimensional average roughness Sah of the top of the convex portion are both more than 200nm and 2000nm or less.

[ concerning element (B) ]

Referring to fig. 1, a cross section in a range of an arbitrary length of 100 μm in the 2 nd direction WD perpendicular to the 1 st direction RD of the plated texture 10S is noted. The section (FIG. 1) in the range of 100 μm in length was defined as an observation section. In the observation cross section, the minimum thickness among the thicknesses of the colored resin layer 11 is defined as DKmin (μ). In the observation cross section, the maximum thickness among the thicknesses of the colored resin layer 11 was defined as DKmax (μm).

Further, in the observation cross section, the content (area%) of the colorant in the colored resin layer 11 is defined as CK. As described above, in the present specification, the colorant content CK is expressed as an area ratio (area%) of the colorant in the observation section.

Here, F1 is defined by formula (1).

F1＝DKmin×CK (1)

In this case, F1 is 15.0 or less.

F1 is an index of the coloring concentration of the colored resin layer 11. If F1 is greater than 15.0, the thickness of the colored resin layer 11 is too thick or the colorant content CK is too large. In this case, the coloring of the colored resin layer 11 is excessively concentrated, and the plating texture 10S of the galvanized layer 10 is difficult to visually confirm. If F1 is 15.0 or less, the plated texture 10S on the surface of the galvanized layer 10 can be sufficiently visually confirmed while having an appearance colored by the colored resin layer 11 on condition that the requirements (a) and (C) are satisfied. The preferable upper limit of F1 is 14.0, more preferably 13.5, still more preferably 13.0, and still more preferably 12.5. The lower limit of F1 is not particularly limited. The lower limit of F1 is, for example, 4.0.

The thickness of the colored resin layer 11 is measured by the following method. A sample having a cross section perpendicular to the 1 st direction RD of the plating texture 10S on the surface was collected. An observation cross section in the range of 100 μm in length in the 2 nd direction WD in the sample was observed with a reflection electron image (BSE) of 2000 times using a Scanning Electron Microscope (SEM). In observation by a Scanning Electron Microscope (SEM) reflected electron image (BSE), the base steel sheet 100, the galvanized layer 10, and the colored resin layer 11 can be easily distinguished by contrast (contrast). In the observation cross section, the thickness of the coloring resin layer 11 was measured at a pitch of 0.5 μm in the 2 nd direction WD. Among the thicknesses obtained by the measurement, the smallest thickness was defined as a minimum thickness DKmin (μm). Among the thicknesses obtained by the measurement, the maximum thickness was defined as the maximum thickness DKmax (μm). If it is necessary to determine whether or not the resin layer is a colored resin layer 11 (i.e., whether or not the resin contains a colorant), whether or not the resin layer is a colored resin layer 11 can be determined by TEM observation described later.

The colorant content CK (area%) in the colored resin layer 11 was determined by the following method. A sample having a cross section perpendicular to the 1 st direction RD of the plating texture 10S on the surface was collected. In the sample, a cross section perpendicular to the 1 st direction RD of the plated texture 10S is defined as a viewing plane. Using a focused ion beam device (FIB: Focus)ed Ion Beam), from the samples, film samples capable of observing the colored resin layer 11 and the galvanized layer 10 on the observation surface were prepared. The thickness of the film sample is set to be 50 to 200 nm. The prepared film sample was observed with a Transmission Electron Microscope (TEM) so that the length of the observation surface of the film sample in the direction perpendicular to the thickness direction of the colored resin layer 11 (i.e., the 2 nd direction WD) was 3 μm and the observation surface of the film sample had a field of view including the length of the entire colored resin layer in the thickness direction of the colored resin layer (i.e., the 3 rd direction TD). In TEM observation, the resin 31 and the colorant 32 in the colored resin layer 11 can be identified by contrast. The total area A1(μm) of the plurality of colorants in the colored resin layer 11 in the field of view was determined²). And the area (. mu.m) of the colored resin layer 11 in the field of view was determined²). Based on the total area a1 and the area a0 thus obtained, the content of the colorant (area%) in the colored resin layer 11 was obtained by the following equation.

CK＝A1/A0×100

[ concerning the essential component (C) ]

In an observation cross section of the plated texture 10S in the range of 100 μm in length in the 2 nd direction WD, wherein the observation cross section is a cross section perpendicular to the 1 st direction RD of the plated texture 10S, F2 is defined by equation (2).

F2＝(DKmax-DKmin)×CK (2)

At this time, F2 is greater than 1.0.

F2 is an index of the contrast of lightness in the colored resin layer 11. If F2 is 1.0 or less, the brightness contrast in the colored resin layer 11 is low. In this case, the contrast of the lightness of the colored resin layer 11 cannot be sufficiently utilized for visual confirmation of the plated texture 10S. Therefore, the plated texture 10S under the colored resin layer 11 is difficult to visually confirm.

If F2 is higher than 1.0, the contrast of lightness in the colored resin layer 11 is sufficiently high. In this case, the contrast of the lightness of the colored resin layer 11 can be sufficiently utilized for visual confirmation of the plated texture 10S. As a result, the plated texture 10S under the colored resin layer 11 can be sufficiently visually confirmed on the premise that the requirements (a) and (B) are satisfied.

A preferred lower limit of F2 is 2.0 or more than 2.0, more preferably 2.2, still more preferably 2.4. The upper limit of F2 is not particularly limited. The upper limit of F2 is, for example, 15.0.

[ lightness L when the plated steel sheet is observed from the colored resin layer side^*(SCI)]

The brightness of the entire surface of the plated steel sheet 1 according to embodiment 1 is not particularly limited as long as it satisfies the above-described requirements such as F2, which is an index of the contrast of brightness in the concave portions and the convex portions. Therefore, the lightness L when the plated steel sheet is observed from the colored resin layer side^*The upper and lower limits of (SCI) are not particularly limited. On the other hand, the lightness L when the plated steel sheet is observed from the colored resin layer side^*The (SCI) may be 45 or less. Lightness L of plated Steel sheet^*The lower the (SCI), the more the degree of blackness of the plated steel sheet observed with the naked eye increases. In a general plated steel sheet, if the lightness L of the surface is defined^*If (SCI) is 45 or less, the plating texture becomes difficult to visually confirm. On the other hand, since the plated steel sheet 1 of embodiment 1 satisfies the requirements (a) to (C), the lightness L when the plated steel sheet is viewed from the colored resin layer side^*(SCI) of 45 or less, and the texture of the surface of the galvanized layer can be visually confirmed.

Lightness L^*(SCI) is the lightness obtained by SCI measurement. The SCI system is also referred to as a specular reflection light-containing system, and means a method for measuring a color without removing specular reflection light. The lightness measurement method according to the SCI method is defined in JIS Z8722 (2009). In the SCI system, since measurement is performed without removing specular reflection light, the color of an actual object (so-called object color) is measured. CIELAB indicates that the color is a uniform color space defined in JIS Z8781 (2013). 3 coordinates of CIEL AB are expressed as L^*Value a^*Value b^*The values are represented. L is^*The value represents lightness and is represented by 0 to 100. L is^*A value of 0 indicates black, L^*A value of 100 indicates a diffuse reflection color of white.

[ thickness of colored resin layer 11]

In the plated steel sheet 1 according to embodiment 1, the average thickness of the colored resin layer 11 is preferably 10.0 μm or less. If the thickness of the colored resin layer 11 exceeds 10.0 μm, it is easy to smooth (level) only the colored resin layer 11, and the difference between the impression of reflection at the surface of the colored resin layer 11 and the impression of the plating texture 10S that can be visually confirmed becomes large. In this case, the metallic feeling of the plated steel sheet 1 is reduced. If the average thickness of the colored resin layer 11 is 10.0 μm or less, the plating texture 10S of the galvanized layer 10 can be visually confirmed and the metallic feeling is sufficiently improved on the premise that all the requirements (a) to (C) described above are satisfied. The upper limit of the average thickness of the colored resin layer 11 is more preferably 9.0 μm, and still more preferably 8.0 μm.

Further, a preferable lower limit of the average thickness of the colored resin layer 11 is 0.5 μm. If the average thickness of the colored resin layer 11 is 0.5 μm or more, the corrosion resistance is further improved. The lower limit of the average thickness of the colored resin layer 11 is more preferably 0.7 μm, still more preferably 1.0 μm, yet more preferably 2.0 μm, and yet more preferably 3.0 μm.

The average thickness of the colored resin layer 11 is measured by the following method. The arithmetic average of the thicknesses measured at 0.5 μm pitch in the 2 nd direction WD in the above observation cross section was defined as the average thickness (μm) of the colored resin layer 11.

[ concerning the essential component (D) ]

In the plated steel sheet 1 according to embodiment 1, the three-dimensional average roughness Sah of the top of the convex portion is preferably greater than 5nm and not more than 200nm (requirement (D)).

Referring to fig. 7, in the concave portions 10RE and the convex portions 10CO of the plating texture 10S formed on the surface of the galvanized layer 10, before polishing, fine concave and convex portions (fine concave portions SRE and fine convex portions SCO) of nanometer order due to plating crystals are present on the surface of the concave portions 10RE and the surface of the convex portions 10 CO. That is, the roughness of the fine irregularities (the fine recessed portions SRE and the fine raised portions SCO) in the raised portions 10CO is as rough as the roughness of the fine irregularities (the fine recessed portions SRE and the fine raised portions SCO) in the recessed portions 10 RE. Therefore, in the convex portions 10CO, light is diffusely reflected by the fine irregularities, as in the concave portions 10 RE.

Therefore, in the requirement (D), the three-dimensional average roughness Sah of the top of the convex portion is set to be smaller than the three-dimensional average roughness Sas of the bottom of the concave portion. Specifically, as described above, the three-dimensional average roughness Sas of the bottom of the concave portion may be 200nm or more, and the three-dimensional average roughness Sah of the top of the convex portion may be more than 5nm and 200nm or less. In this case, light is easily diffusely reflected in the concave portions 10RE, whereas light is not easily diffusely reflected because the roughness in the convex portions 10CO is lower than that in the concave portions 10 RE. Therefore, in the plating texture 10S of the galvanized layer 10, the convex portions 10CO are in a state of being easily visually confirmed. For example, as shown in fig. 8, the tips of the projections 10CO are polished so that the projections 10CO have a trapezoidal shape. This makes it possible to make the roughness of the fine irregularities (the fine recesses SRE and the fine protrusions SCO) in the convex portions 10CO smaller than the roughness of the fine irregularities (the fine recesses SRE and the fine protrusions SCO) in the concave portions 10 RE.

When the three-dimensional average roughness Sah of the top of the convex portion is 200nm or less, the diffuse reflection of light in the vicinity of the top of the convex portion can be suppressed. In this case, in the plated steel sheet 1 according to embodiment 1 having the colored resin layer 11, the plated texture 10S is further easily visually recognized. The smaller the three-dimensional average roughness Sah of the top of the convex portion is, the more preferable. However, it is extremely difficult to set the three-dimensional average roughness Sah of the top of the projection to 5nm or less. Therefore, in embodiment 1, the three-dimensional average roughness Sah of the top of the convex portion is greater than 5nm and 200nm or less. The upper limit of the three-dimensional average roughness Sah of the top of the convex portion is preferably 190nm, more preferably 180nm, and still more preferably 170 nm.

[ other forms of the colored resin layer 11]

The colored resin layer 11 of the plated steel sheet 1 according to embodiment 1 may further contain an additive in order to impart corrosion resistance, sliding properties, conductivity, and the like to the colored resin layer 11. Examples of the additive for imparting corrosion resistance include known rust inhibitors and inhibitors. Examples of additives for imparting slidability are well-known waxes and beads. Examples of the additive for imparting conductivity are known conductive agents.

[ regarding the surface shape of the colored resin layer 11 when the plated texture 10S is a hair texture (regarding the requirement (E)) ]

The colored resin layer 11 may have a surface shape as described in detail below due to the kind of the plating texture 10S formed on the surface of the galvanized layer 10 as the lower layer.

Here, it is assumed that the plating texture 10S is a hairline. The surface roughness Ra of the colored resin layer 11 in the 1 st direction RD of the plating texture 10S is defined as Ra (cl). The surface roughness Ra of the colored resin layer 11 in the 2 nd direction WD of the plated texture 10S is defined as Ra (cc). F3 is defined by formula (3).

F3＝Ra(CC)/Ra(CL)

In this case, F3 may be 1.10 or more.

F3 is an index relating to the metallic feel of the plated steel sheet when the plating texture 10S is a hair texture. If F3 is less than 1.10, the difference between the impression given by the plating texture 10S (hairline) in the state without the colored resin layer 11 and the impression of reflection of light at the surface of the colored resin layer 11 is too large. In this case, the metallic feeling is lost. In the case where the plated texture 10S is a hairline, if F3 is 1.10 or more, it is possible to suppress a difference between an impression given by the plated texture 10S (hairline) and an impression of reflection of light at the surface of the colored resin layer 11 in a state where the colored resin layer 11 is absent. Therefore, a sufficient metallic feeling can be obtained. The lower limit of F3 is preferably 1.15, more preferably 1.20, and still more preferably 1.25.

The surface roughness ra (cl) was measured by the arithmetic average roughness measurement method specified in JIS B0601 (2013). Specifically, any 10 positions on the surface 11S of the colored resin layer 11 are set as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured at an evaluation length extending in the 1 st direction RD of the plated texture 10S. The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a stylus type roughness meter at a rate of 0.5 mm/sec. From the calculated 10 arithmetic average roughness Ra, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cl).

Similarly, the surface roughness ra (cc) is measured by the arithmetic average roughness measurement method specified in JIS B0601 (2013). Specifically, any 10 positions on the surface 11S of the colored resin layer 11 are set as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured at an evaluation length extending in the 2 nd direction WD of the plated texture 10S. The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a stylus type roughness meter at a rate of 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cc).

[ surface shape of the galvanized layer 10 (regarding the requirement (F)) when the plating texture 10S is a hairline ]

The requirement (F) is the same as the requirement (E) when the plating texture 10S is a hair texture. The surface roughness Ra in the 2 nd direction WD of the surface of the galvanized layer 10 on which the plating texture 10S is formed is defined as Ra (mc). When the plating texture 10S is a hair texture, the surface roughness ra (mc) may be 0.30 μm or more. When the surface roughness ra (mc) is 0.30 μm or more, a sufficient metallic feeling can be obtained when the plating texture 10S is observed from above the colored resin layer 11. The lower limit of the surface roughness Ra (MC) is preferably 0.35. mu.m, and more preferably 0.40. mu.m. The upper limit of the surface roughness ra (mc) is not particularly limited. However, it is sometimes difficult to increase the surface roughness ra (mc) excessively in industrial production. Therefore, the upper limit of the surface roughness Ra (MC) is, for example, 2.00. mu.m. The upper limit of the surface roughness Ra (MC) may be, for example, 1.00. mu.m.

The surface roughness ra (mc) is measured by the arithmetic average roughness measurement method specified in JIS B0601 (2013). Specifically, the colored resin layer 11 of the plated steel sheet 1 is removed by using a solvent or a remover (for example, a product name: Neo revert S-701 manufactured by Sanko chemical Co., Ltd.) which does not attack the galvanized layer 10. In the plating texture 10S of the galvanized layer 10 after the colored resin layer 11 is removed, arbitrary 10 positions are set as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured with an evaluation length extending in the 2 nd direction WD. The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a stylus type roughness meter at a rate of 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (mc).

[ Exposure of base Steel sheet ]

The galvanized layer 10 of the plated steel sheet 1 preferably has a base steel sheet exposure of less than 5%. In embodiment 1, the corrosion resistance is sufficiently ensured by the galvanized layer 10 (zinc plating or zinc alloy plating). However, if the surface of the galvanized layer 10 is ground when the plating texture 10S is provided, and as a result, the base steel sheet is exposed, the long-term corrosion resistance (long-term corrosion resistance) may sometimes decrease due to the influence of galvanic corrosion. Such a decrease in long-term corrosion resistance is often remarkable when the base steel sheet exposure rate is 5% or more. Therefore, in embodiment 1, the base steel sheet exposure is preferably less than 5%.

If the base steel sheet exposure of the galvanized layer 10 is less than 5%, excellent corrosion resistance can be obtained even for a long period of time in addition to appropriate corrosion resistance required for general steel materials. The upper limit of the base steel sheet exposure of the galvanized layer 10 is preferably 3% or less, more preferably 2%, more preferably 1%, and even more preferably 0%.

The base steel sheet exposure was measured by the following method. Specifically, the colored resin layer 11 of the plated steel sheet 1 is removed by using a solvent or a remover (for example, a product name: Neo revert S-701 manufactured by Sanko chemical Co., Ltd.) which does not attack the galvanized layer 10. In the surface of the galvanized layer 10, arbitrary 5 rectangular areas of 1mm × 1mm are selected. EPMA analysis was performed on the selected rectangular area. By image analysis, a region in which Zn is not detected (Zn undetected region) is specified among the rectangular regions. In embodiment 1, a region in which the Zn detection intensity is not more than 1/16 of the intensity when the standard sample (pure Zn) is measured is regarded as a Zn non-detection region. The ratio (% by area) of the total area of the Zn-unmeasured regions in the 5 rectangular regions to the total area of the 5 rectangular regions was defined as the base steel sheet exposure (% by area).

[ other coating films ]

In the plated steel sheet 1 according to embodiment 1, an inorganic coating or an organic-inorganic composite coating may be formed between the colored resin layer 11 and the galvanized layer 10 for the purpose of improving corrosion resistance or adhesion. The inorganic film has light transmittance. The inorganic coating is, for example, an amorphous silica coating, zirconia coating or phosphate coating. The organic-inorganic composite coating has light transmittance. The organic-inorganic composite coating film contains, for example, a silane coupling agent and an organic resin. The organic-inorganic composite coating has light transmittance.

[ morphology of texture ]

Fig. 4 shows a hairline as an example of texture. However, as described above, the form of the texture is not limited to the hairline. The texture may have a plurality of protrusions and a plurality of recesses. Therefore, the convex portion and the concave portion may or may not extend in one direction. The texture may be hair line, extinction, or other forms. The texture may be formed by forming a concave-convex pattern.

[ production method ]

An example of the method for producing the plated steel sheet 1 of embodiment 1 will be described below. The manufacturing method described below is an example for manufacturing the plated steel sheet 1 according to embodiment 1. Therefore, the plated steel sheet 1 having the above-described configuration can be manufactured by a manufacturing method other than the manufacturing method described below. However, the manufacturing method described below is a preferred example of the manufacturing method of the plated steel sheet 1 according to embodiment 1.

The manufacturing method of embodiment 1 includes: a preparation step (S1) of preparing a base steel sheet 100, a base steel surface texture forming step (S2) of forming a base material texture 100S on the surface of the base steel sheet 100, a galvanization treatment step (S3) of forming a galvanized layer 10 on the base steel sheet 100, a galvanization surface texture forming step (S4) performed when the surface of the galvanized layer 10 is subjected to further texture processing as an optional step, a polishing step (S5) of polishing the top end of the convex portion 10CO of the galvanized layer 10 as necessary as an optional step, and a colored resin layer forming step (S6) of forming a colored resin layer 11 on the galvanized layer 10. Hereinafter, each process will be explained.

[ preparation Process (S1) ]

In the preparation step (S1), the base steel sheet 100 is prepared. The base steel plate 100 may be a steel plate or may have another shape. If the base steel sheet 100 is a steel sheet, the base steel sheet 100 may be a hot-rolled steel sheet or a cold-rolled steel sheet

[ base Material surface texture Forming Process (S2) ]

The base material surface texture forming step (S2) is to form a base material texture 100S on the base material surface. In this case, the plated steel sheet had the structure shown in fig. 1. In the base material surface texture forming step (S2), the surface of the base material steel sheet 100 is subjected to known texture processing to form the base material texture 100S on the surface of the base material steel sheet 100. If the base material texture 100S is a hairline, a known hairline process is performed. Examples of methods for processing hair line include: a method of forming hair lines by polishing the surface with a known polishing tape, a method of forming hair lines by polishing the surface with a known polishing brush, a method of forming hair lines by roll transfer with a roller having a hair line shape, and the like. The length, depth, and frequency of the hair line can be adjusted by adjusting the particle size of a known polishing tape, the particle size of a known abrasive brush, or the surface shape of a roller.

[ Zinc plating Process (S3) ]

In the galvanizing process (S3), the prepared base steel sheet 100 is galvanized to form the galvanized layer 10 on the surface of the base steel sheet 100.

The zinc plating treatment may be performed by a known method. For example, the galvanized layer 10 is formed by a well-known electroplating method. In this case, as the zinc plating bath and the zinc alloy plating bath, known baths may be used. As the plating 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, combinations thereof, and the like are exemplified. The zinc alloy plating bath contains, for example, 1 or more kinds of single ions or complex ions selected from the group consisting of Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, and Zr in addition to Zn ions.

The chemical composition, temperature, flow rate, and conditions (current density, energization pattern, and the like) during the plating treatment of the zinc plating bath and the zinc alloy plating bath in the zinc plating treatment can be appropriately adjusted. The thickness of the galvanized layer 10 in the zinc plating treatment can be adjusted by adjusting the current value and time within the range of the current density at the time of the zinc plating treatment.

The base material steel plate 100 is formed with a base material grain 100S. Therefore, if the galvanized layer 10 is formed by performing the galvanizing treatment on the base steel sheet 100, the plated grain 10S along the base grain 100S is formed on the surface of the galvanized layer 10. Through the above manufacturing steps, a plated steel sheet including the base steel sheet 100 having the base material grain 100S formed thereon and the galvanized layer 10 having the plated grain 10S formed thereon can be manufactured.

[ concerning the galvanized surface texture forming step (S4) and the polishing step (S5) ]

The galvanized surface texture forming step (S4) and the polishing step (S5) are optional steps. That is, the galvanized surface texture forming step (S4) and the polishing step (S5) may not be performed. The galvanized surface texture forming process (S4) may be performed without performing the grinding process (S5). The polishing step (S5) may be performed without performing the galvanized surface texture forming step (S4). Both the galvanized surface texture forming step (S4) and the polishing step (S5) may be performed. When the galvanized surface texture forming step (S4) and the polishing step (S5) are performed, either step may be performed first. Both the galvanized surface texture forming step (S4) and the polishing step (S5) are steps of grinding the tips of the projections 10CO of the plated texture 10S of the galvanized layer 10. Hereinafter, each step will be explained.

[ Zinc-plated surface texture formation step (S4) ]

The galvanized surface texture forming process (S4) is an optional process. That is, the galvanized surface texture forming step (S4) may be performed or may not be performed. In the galvanized surface texture forming step (S4), the tips of the projections 10CO in the plated texture 10S on the surface of the galvanized layer 10 shown in fig. 7 are ground into a trapezoidal shape as shown in fig. 8 so that the three-dimensional average roughness Sah of the projection tops is greater than 5nm and 200nm or less. Specifically, in the galvanized surface texture forming step (S4), the surface of the galvanized layer 10 (plated texture 10S) of the plated steel sheet is subjected to known texture processing, whereby the three-dimensional average roughness Sah of the top of the protrusions of the plated texture 10S is set to be greater than 5nm and 200nm or less. At this time, the concave portion of the plated texture 10S is hardly ground. Therefore, the three-dimensional average roughness Sas of the bottom of the concave portion is maintained at more than 200nm and 2000nm or less.

If the plating texture 10S is a hairline, a known hairline process is performed. As a hairline processing method, for example, there are: a method of forming hair lines by polishing the surface with a known polishing tape, a method of forming hair lines by polishing the surface with a known polishing brush, a method of forming hair lines by roll transfer with a roller having a hair line shape, and the like. The degree of grinding of the tips of the convex portions 10CO of the plating texture 10S on the surface of the galvanized layer 10 can be adjusted by adjusting the particle size of a known polishing tape, the particle size of a known polishing brush, or the surface shape of a roll. That is, by adjusting the particle size of a known polishing tape, the particle size of a known polishing brush, or the surface shape of a roll, the three-dimensional average roughness Sas of the top of the protrusions can be adjusted to be more than 5nm and 200nm or less while maintaining the three-dimensional average roughness Sas of the bottom of the protrusions to be more than 200nm and 2000nm or less. When the texturing is performed in the galvanized surface texture forming step (S4), not only the three-dimensional average roughness Sas of the bottom of the recessed portion is maintained at more than 200nm and 2000nm or less, but also the three-dimensional average roughness Sah of the top of the raised portion is adjusted to more than 5nm and 200nm or less, and a new hairline can be imparted to the plated texture 10S. The base steel sheet exposure rate can be adjusted by adjusting the grain size of a known polishing tape, the grain size of a known polishing brush, or the surface shape of a roll in the galvanized surface texture forming step (S4).

[ polishing Process (S5) ]

The grinding step (S5) is an optional step. That is, the polishing step (S5) may not be performed. In the polishing step (S5), the tips of the projections 10CO in the plating texture 10S on the surface of the galvanized layer 10 shown in fig. 7 are polished to have a trapezoidal shape as shown in fig. 8 so that the three-dimensional average roughness Sah of the projection tops is greater than 5nm and not more than 200 nm. By this polishing treatment, the three-dimensional average roughness Sas of the bottom of the recessed portion is maintained at more than 200nm and 2000nm or less, and the three-dimensional average roughness Sah of the top of the projected portion is set at more than 5nm and 200nm or less. As the polishing treatment, for example, there are: a method of polishing a surface with a known polishing tape, a method of polishing a surface with a known polishing brush, and the like. The shape of the convex portions 10CO and the roughness of the surface of the convex portions 10CO can be adjusted by adjusting the particle size of a known polishing tape or the particle size of a known polishing brush. That is, the three-dimensional average roughness Sah of the top of the convex portion can be adjusted by adjusting the particle size of a well-known polishing tape or the particle size of a well-known polishing brush. The grinding amount (grinding amount) in the grinding step (S5) is smaller than that in the galvanized surface texture forming step (S4). The base steel sheet exposure rate may be adjusted by adjusting the particle size of a known polishing tape or the particle size of a known polishing brush in the polishing step (S5).

The polishing step (S5) may be performed simultaneously with the aforementioned galvanized surface texture forming step (S4). By doing so simultaneously, production efficiency can be improved.

[ colored resin layer Forming Process (S6) ]

In the colored resin layer forming step (S6), the colored resin layer 11 is formed on the galvanized layer 10 of the plated steel sheet having the plating texture 10S formed thereon. Hereinafter, the coloring resin layer forming process (S6) will be described in detail.

The paint used for forming the colored resin layer 11 preferably follows the surface shape of the steel material immediately after being applied to the plated steel sheet, and after once reflecting the surface shape of the steel material, the paint has a slow leveling property. That is, it is preferable that the viscosity is low if the shear rate is high, and the viscosity is high if the shear rate is low. Specifically, it is preferable that the viscosity is 10[ Pa · s ] or more at a shear rate of 0.1[1/sec ], and the shear viscosity is 0.01[ Pa · s ] or less at a shear rate of 1000[1/sec ].

The shear viscosity of the coating material can be adjusted by the following method. If the coating material is an aqueous emulsion coating material, a known viscosity modifier having hydrogen bonding property may be added for adjustment. Such hydrogen-bonding viscosity modifiers are mutually constrained by hydrogen bonds at a low shear rate. Therefore, the viscosity of the coating material can be increased. On the other hand, at high shear rates, hydrogen bonds are cut. Therefore, the viscosity of the coating material may be reduced.

The surface shape of the colored resin layer 11 can be adjusted by adjusting the shear viscosity of the paint used for forming the colored resin layer 11.

The method of forming the colored resin layer 11 on the galvanized layer 10 may be a well-known method. For example, the coating material with the adjusted viscosity is applied to the galvanized layer 10 by a spray coating method, a roll coating method, a curtain coating method, or a dip coating method. Then, the paint on the galvanized layer 10 is dried naturally or by baking to form a colored resin layer 11. The drying temperature, drying time, baking temperature and baking time can be suitably adjusted. The three-dimensional average roughness Saave, the minimum thickness DKmin of the colored resin layer 11, and the maximum thickness DKmax can be adjusted by adjusting the shear viscosity of the paint used for forming the colored resin layer 11, the coating amount on the galvanized layer 10, and the like. Further, by adjusting the content of the colorant in the paint, the colorant content CK in the colored resin layer 11 can be adjusted.

Through the above manufacturing steps, the plated steel sheet 1 according to embodiment 1 can be manufactured. The plated steel sheet 1 according to embodiment 1 is not limited to the above-described manufacturing method, and the plated steel sheet 1 according to embodiment 1 may be manufactured by a manufacturing method other than the above-described manufacturing method as long as the plated steel sheet 1 having the above-described configuration can be manufactured. However, the above-described manufacturing method is suitably used for manufacturing the plated steel sheet 1 according to embodiment 1.

(embodiment 2)

In the plated steel sheet according to embodiment 1, it is attempted to improve both the adhesion to the colored resin layer and the visibility of the texture of the surface of the galvanized layer. However, depending on the application of the plated steel sheet, the texture visibility may be prioritized over the adhesion of the colored resin layer. Therefore, the present inventors have studied a plated steel sheet having a colored appearance and a galvanized layer with a surface texture having a higher visibility. As described in

patent documents

1 and 2, a galvanized steel sheet in which a transparent resin layer is formed on a galvanized layer has been proposed. Therefore, the present inventors have first tried to produce a galvanized steel sheet colored by adding a coloring agent to a resin layer formed on a galvanized layer.

As a result, it was found that: when the coloring agent is contained in the resin layer, the texture formed on the surface of the galvanized layer may not be visually recognized depending on the conditions. Therefore, the present inventors have investigated and studied factors that affect visual confirmation of texture when a colorant is contained in a resin. As a result, the present inventors have obtained the following findings.

If a colored resin layer containing a coloring agent is formed on a zinc-plated layer having a texture formed on the surface thereof, the content of the coloring agent in the colored resin layer and the thickness of the colored resin layer affect the visual confirmation of the texture. Specifically, if the content of the colorant in the colored resin layer is too large, the texture becomes not visually confirmed. Further, if the colored resin layer is too thick, the texture becomes impossible to be confirmed with the naked eye.

In addition, the shape of the texture may also have an effect on the visual confirmation of the texture. When the texture is formed on the surface of the galvanized layer, not only the texture unevenness but also minute unevenness due to the crystal of the galvanized layer are present on the surface of the texture layer. If the fine irregularities caused by the crystals of the zinc plating are large, light is diffusely reflected by the fine irregularities caused by the crystals of the zinc plating. In this case, the gloss of the texture is reduced, and the texture is whitened. Therefore, if a colored resin layer is formed on the galvanized layer, the texture becomes difficult to be visually confirmed. Therefore, from the viewpoint of further improving the visibility of the texture, it is preferable to suppress the roughness (fine unevenness) of the microscopic region at the top (convex portion) or the bottom (concave portion) of the texture extending in one direction.

In addition, in a cross section perpendicular to the extending direction of the grain, the thickness of the resin formed on the grain varies depending on the unevenness of the grain. Fig. 9 is a schematic view of a cross section perpendicular to the extending direction of the grain in the plated steel sheet according to the present embodiment. Referring to fig. 9, the plated steel sheet includes a galvanized layer 10 'and a colored resin layer 11'. The surface of the galvanized layer 10 'is formed with a texture 10S'. The texture 10S ' includes Convex portions 10CO ' (Convex) and concave portions 10RE ' (process).

The colored resin layer 11 'is formed on the surface of the galvanized layer 10'. Therefore, the surface 11S 'of the colored resin layer 11' reflects the unevenness of the grain 10S 'to some extent, but is more planarized than the grain 10S'. Specifically, in the surface 11S ' of the colored resin layer 11 ', the convex portions 11CO ' are formed at portions corresponding to the convex portions 10CO ' of the texture 10S '. The height of the convex portion 11CO 'is lower than that of the convex portion 10 CO'. That is, the surface 11S ' of the colored resin layer 11 ' is more planarized than the surface of the texture 10S '.

Here, the maximum thickness (μm) of the colored resin layer 11 ' in the range of 100 μm in length in the direction perpendicular to the extending direction of the grain 10S ' is defined as DKmax '. Further, the minimum thickness (μm) of the colored resin layer 11 'is defined as DKmin'. In order to make the texture 10S 'visually recognizable even when colored by the colored resin layer 11', the content of the coloring agent in the colored resin layer 11 'and the thickness of the colored resin layer 11' are limited to some extent as described above. Under this constraint, the difference between the maximum thickness DKmax ' and the minimum thickness DKmin ' of the colored resin layer 11 ' is reflected in the lightness difference. Specifically, by making the difference between the maximum thickness DKmax 'and the minimum thickness DKmin' of the colored resin layer 11 'large to some extent, the concave portions 10 RE' and the convex portions 10CO 'of the grain 10S' are different in lightness. As a result, the grain 10S 'can be visually recognized even when the colored resin layer 11' is formed.

Based on the above findings, the present inventors have found that a plated steel sheet having a colored appearance and a texture of the surface of a zinc-plated layer which can be visually confirmed can be obtained by the following (a ') to (C'): (a ') the roughness of the fine areas of the convex portions 10 CO' and the concave portions 10RE 'of the grain 10S', the thickness and the colorant content of the colored resin layer 11 ', and (C') the difference between the maximum thickness DKmax 'and the minimum thickness DKmin' of the colored resin layer 11 'in the cross section perpendicular to the extending direction of the grain 10S' is set to a certain extent.

The plated steel sheet according to embodiment 2 completed based on the above findings has the following configuration.

[11] The plated steel sheet of (1) comprises:

a base steel plate,

A zinc-plated layer formed on the surface of the base steel sheet, and

a colored resin layer formed on the zinc-plated layer,

the colored resin layer contains a coloring agent,

the plated steel sheet satisfies all of the following conditions (A ') to (C'):

(A ') A roughness profile in a range of 1000[ mu ] m in length in a direction perpendicular to the extending direction of the texture is measured, 10 positions specified in order from the beginning of the lower height among the positions on the roughness profile obtained by the measurement are defined as bottom points of concavities, 10 positions specified in order from the beginning of the higher height among the positions on the roughness profile obtained by the measurement are defined as apexes of convexities, and the three-dimensional average roughness Saave ' of a minute region of 1[ mu ] m × 1[ mu ] m centered around each bottom point of concavities and each apex of convexities is measured, and the arithmetic average of the three-dimensional average roughness Saave ' obtained by the measurement is defined as the three-dimensional average roughness Saave ', the three-dimensional average roughness Saave ' is greater than 5nm and 200nm or less.

DKmin’×CK’≤15.0 (1’)；

(DKmax’-DKmin’)×CK’>1.0 (2’)。

[12] the plated steel sheet according to [11], wherein,

the texture may be a hair line or a hairline,

the plated steel sheet may satisfy the following (D ') and (E'):

Ra(CC)’≥Ra(CL)’×1.10 (3’)；

[13] The plated steel sheet according to [11] or [12], wherein,

Hereinafter, the plated steel sheet of embodiment 2 will be described in detail.

[ plated steel sheet 1' ]

Fig. 10 is a sectional view of a plated steel sheet 1' according to embodiment 2. In fig. 10, the direction perpendicular to the paper surface is defined as the extending direction RD ' of the grain 10S ' (i.e., the rolling direction of the plated steel sheet 1 '). The thickness direction of the plated steel sheet 1 'is defined as a thickness direction TD'. In the plated steel sheet 1 ', a direction perpendicular to the extending direction RD' and the thickness direction TD 'of the grain is defined as a width direction WD'. Note that RD ', TD ', and WD ' in the definitions are substantially the same as RD, TD, and WD in embodiment 1.

Referring to fig. 10, a plated steel sheet 1' according to embodiment 2 includes: base steel sheet 100 ', galvanized layer 10 ', colored resin layer 11 '. The galvanized layer 10 'is formed on the surface of the base steel sheet 100'. The colored resin layer 11 ' is formed on the surface (texture) 10S ' of the galvanized layer 10 '. The galvanized layer 10 ' is disposed between the base steel sheet 100 ' and the colored resin layer 11 '. Hereinafter, the base steel sheet 100 ', the galvanized layer 10 ', and the colored resin layer 11 ' will be described.

[ base Steel sheet 100' ]

The base steel sheet 100' may be a known steel sheet applied to a plated steel sheet (e.g., a zinc-plated steel sheet, a zinc alloy-plated steel sheet, a hot-dip galvanized steel sheet, an alloyed hot-dip galvanized steel sheet, etc.) according to various mechanical properties (e.g., tensile strength, workability, etc.) required for the plated steel sheet to be produced. For example, as the base steel sheet 100', a steel sheet for electrical appliance use may be used, and a steel sheet for vehicle outer panel use may be used. The base steel sheet 100' may be a hot-rolled steel sheet or a cold-rolled steel sheet.

[ concerning the galvanized layer 10' ]

The galvanized layer 10 'is formed on the surface of the base steel sheet 100'. In embodiment 2, the galvanized layer 10 ' is disposed between the base steel sheet 100 ' and the colored resin layer 11 '. The galvanized layer 10' may be formed by a well-known galvanizing process. Specifically, the galvanized layer 10' can be formed by any of a plating method and a hot-dip plating method, for example. In this specification, the zinc-plated layer 10' also includes a zinc-alloy plated layer. More specifically, the galvanized layer 10' is a concept including a zinc plated layer, a zinc alloy plated layer, a hot-dip galvanized layer, and an alloyed hot-dip galvanized layer.

The zinc plating layer 10' in embodiment 2 may have a known chemical composition. For example, the Zn content in the chemical composition of the galvanized layer 10' may be 65% by mass or more. If the Zn content is 65% by mass or more, the sacrificial corrosion prevention function can be remarkably exhibited, and the corrosion resistance of the plated steel sheet 1' is remarkably improved. The preferable lower limit of the Zn content in the chemical composition of the galvanized layer 10' is 70%, and more preferably 80%.

The chemical composition of the galvanized layer 10' preferably contains 1 element or 2 or more elements selected from Al, Co, Cr, Cu, Fe, Ni, P, Si, Sn, Mg, Mn, Mo, V, W, Zr in addition to Zn. When the galvanized layer 10 'is a zinc-plated layer, the chemical composition of the galvanized layer 10' further preferably contains at least 1 element selected from Fe, Ni, and Co in a total amount of 5 to 20 mass%, and the remainder is composed of Zn and impurities. When the galvanized layer 10 'is a hot-dip galvanized layer, the chemical composition of the galvanized layer 10' further preferably contains at least 1 or more elements selected from Mg, Al, and Si in a total amount of 5 to 20 mass%, and the remainder is made up of Zn and impurities. In these cases, the galvanized layer 10' further exhibits excellent corrosion resistance.

The galvanized layer 10' may also contain impurities. Here, the impurities mean impurities mixed in the raw materials or impurities mixed in the production process. The impurities include, for example, Ti, B, S, N, C, Nb, Pb, Cd, Ca, Pb, Y, La, Ce, Sr, Sb, O, F, Cl, Zr, Ag, W, H, etc. In the chemical composition of the galvanized layer 10', the total content of impurities is preferably 1% or less.

The chemical composition of the galvanized layer 10' can be measured, for example, by the following method. The colored resin layer 11 ' of the plated steel sheet 1 ' is removed with a solvent or a remover (for example, a product name: Neo Rever S-701 manufactured by Sanko chemical Co., Ltd.) which does not attack the galvanized layer 10 '. Then, the galvanized layer 10' is dissolved using hydrochloric acid to which an inhibitor is added. The dissolved solution was subjected to ICP (Inductively Coupled Plasma) analysis using an ICP emission spectrometer to determine the Zn content. If the obtained Zn content is 65% or more, the plating layer to be measured is judged to be a zinc plating layer 10'.

[ amount of adhesion to the galvanized layer 10' ]

Zinc coatingThe amount of the adhesion 10' is not particularly limited, and a known amount is sufficient. The preferable adhesion amount of the zinc-plated layer 10' is 5.0 to 120.0g/m². If the adhesion amount of the zinc plating layer 10' is 5.0g/m²As described above, when the later-described texture is provided to the galvanized layer 10 ', the exposure of the base steel sheet (base steel sheet 100') can be suppressed. Further preferable lower limit of the adhesion amount of the zinc plating layer 10' is 7.0g/m²More preferably 10.0g/m². The upper limit of the adhesion amount of the galvanized layer 10' is not particularly limited. From the viewpoint of economy, if the zinc-plated layer 10' is formed by the electroplating method, the upper limit of the adhesion amount is preferably 40.0gm²Further, it is preferable that the upper limit is 35.0g/m²More preferably 30.0g/m²。

[ about the colored resin layer 11' ]

The colored resin layer 11 ' is formed on the surface (texture) 10S ' of the galvanized layer 10 '. Fig. 11 is an enlarged view of the colored resin layer 11' shown in fig. 10. Referring to fig. 11, a colored resin layer 11 ' includes a resin 31 ' and a colorant 32 '. The colorant 32 'is contained in the resin 31'. The resin 31 'and the colorant 32' will be described below.

[ about resin 31' ]

The resin 31' is a resin having light transmittance. In embodiment 2, "a resin having light transmittance" means that when the plated steel sheet 1 'provided with the colored resin layer 11' containing the colorant 32 'and the resin 31' is placed in an environment corresponding to sunlight at noon on a clear day (the illuminance is about 65000 lux), the texture 10S 'of the galvanized layer 10' can be visually confirmed. The resin 31 'functions as a binder for fixing the colorant 32'.

The resin 31' is not particularly limited as long as it is a resin having light transmittance as defined above, and a known natural resin or a known synthetic resin can be used. The resin 31' in embodiment 2 may be 1 or 2 or more selected from the group consisting of epoxy resins, urethane resins, polyester resins, phenol resins, polyethersulfone resins, melamine alkyd resins, acrylic resins, polyamide resins, polyimide resins, silicone resins, polyvinyl acetate resins, polyolefin resins, polystyrene resins, vinyl chloride resins, and vinyl acetate resins, for example.

[ with regard to the colorant 32' ]

The coloring agent 32 ' is contained in the resin 31 ' to color the colored resin layer 11 '. The colorant 32' in embodiment 2 is a known colorant, and widely includes colorants used for coloring a resin layer formed on a surface of a steel sheet, such as inorganic pigments, organic pigments, and dyes. Colorant 32' is a chromatic colorant. Chromatic refers to a color having attributes of hue, lightness, and chroma. The colorant 32' contains, for example, 1 or more selected from inorganic pigments, organic pigments, and dyes. The colorant 32' is more preferably a pigment (inorganic pigment and/or organic pigment) from the viewpoint of durability against ultraviolet rays.

In the case where the colorant 32 'is an inorganic pigment, the colorant 32' is, for example, a neutralized precipitation pigment (sulfate, carbonate, etc.) and/or a firing pigment (metal sulfide, metal oxide, polyvalent metal composite oxide, etc.). When the colorant 32 'is an organic pigment, the colorant 32' is, for example, 1 or more selected from chlorine pigments, azo pigments (soluble azo lake pigments, insoluble azo pigments, etc.), acid condensation pigments, polycyclic pigments (phthalocyanine pigments, indigo pigments, quinacridone pigments, anthraquinone pigments, etc.), metal complex pigments (azo chelate pigments, transition metal complex pigments, etc.). When the colorant 32 'is a dye, the colorant 32' is, for example, 1 or more selected from azo dyes, indigo dyes, anthraquinone dyes, sulfur dyes, and carbonium dyes.

The color of the colorant 32' is not particularly limited. The colorant 32 'is, for example, carbon black (C'), iron black (Fe)₃O₄) Black in color of (c). However, the colorant 32 'is not limited to black, and may be another colorant 32' (white, magenta, yellow, green-blue, red, orange, yellow, green, cyan, blue, violet, etc.).

When the colorant 32' is a pigment, the particle diameter is not particularly limited. When the colorant 32' is a pigment, the maximum value of the primary particle diameter is, for example, 3nm to 1000 nm.

[ concerning the texture 10S 'formed on the surface of the galvanized layer 10' ]

The surface of the galvanized layer 10 ' of the plated steel sheet 1 ' has a texture 10S '. That is, the galvanized layer 10 ' of the plated steel sheet 1 ' has the texture 10S ' on the surface thereof. The texture 10S' extends in one direction. In embodiment 2, "texture" refers to an uneven pattern formed on the surface of the galvanized layer 10' by a physical or chemical method. The preferred texture is hair lines. The hairline is a linear uneven pattern extending in one direction.

[ case where the texture 10S' is a hairline ]

Fig. 12 is a top view of a zinc plating layer 10 'having hairlines formed on the surface as a texture 10S'. Referring to fig. 12, the hairline 10S 'is a linear concave-convex pattern formed on the surface of the galvanized layer 10'. The extension direction RD 'of the hair line 10S' is the same direction. The same direction as used herein means that 90% or more of the angles formed by adjacent hairlines arranged in the direction WD ' perpendicular to the extending direction RD ' of the hairline 10S ' are smaller than ± 5 ° when the galvanized layer 10 ' is viewed from the thickness direction TD ' (i.e., in the plan view of fig. 12).

[ concerning the requirements (A ') to (C') ]

The plated steel sheet 1 ' according to embodiment 2 having the above-described configuration further satisfies all of the following conditions (a ') to (C ').

Requirement (A'):

the roughness profile in the range of 1000 μm in length in the direction WD ' perpendicular to the extending direction RD ' of the texture 10S ' is measured, and 10 positions specified in order from the low height among the positions on the measured roughness profile are defined as the bottom points of the recesses, and 10 positions specified in order from the high height among the positions on the measured roughness profile are defined as the top points of the projections. The three-dimensional average roughness Sa' of a minute region of 1 μm × 1 μm centered on the bottom point of each concave portion and the top point of each convex portion was measured. The arithmetic average of the three-dimensional average roughness Sa 'obtained by the measurement is defined as a three-dimensional average roughness Saave'. In this case, the three-dimensional average roughness Saave' is greater than 5nm and not more than 200 nm.

Element (B'):

in the range of 100 μm in length in the direction WD ' perpendicular to the extending direction RD ' of the texture 10S ', the minimum thickness (μm) of the colored resin layer 11 ' is defined as DKmin '. Further, the content (area%) of the colorant 32 ' in the colored resin layer 11 ' is defined as CK '. At this time, the minimum thickness DKmin ' of the colored resin layer 11 ' and the content CK ' of the colorant 32 ' satisfy formula (1 ').

DKmin’×CK’≤15.0 (1’)

Requirement (C'):

in the range of 100 μm in length in the direction WD ' perpendicular to the extending direction RD ' of the texture 10S ', the maximum thickness (μm) of the colored resin layer 11 ' is defined as DKmax '. At this time, the maximum thickness DKmax ' of the colored resin layer 11 ', the minimum thickness DKmin ' of the colored resin layer 11 ', and the content CK ' of the colorant 32 ' satisfy formula (2 ').

(DKmax’-DKmin’)×CK’>1.0 (2’)

Hereinafter, each requirement will be described in detail.

[ concerning element (A') ]

Fig. 13 is a diagram showing the roughness profile of the texture 10S 'formed on the surface of the galvanized layer 10'. Referring to fig. 13, an arbitrary range having a length of 1000 μm is selected in a direction WD ' perpendicular to the extending direction RD ' of the texture 10S '. The roughness profile of the texture 10S' is measured over a selected length of 1000 μm. The resulting roughness profile is assumed to be in the shape of fig. 13.

Of the positions on the measured roughness profile, 10 low-height positions are designated in order of the lowest height from the lowest-height position. The designated positions are defined as recess bottom points PRE1 ', PRE2 ', …, PRE10 ' in order from the beginning of the height being low. Further, of the positions on the measured roughness profile, 10 high positions are designated in order of height from the highest position. The designated positions are defined as projection apexes PCO1 ', PCO2 ', … and PCO10 ' in order from the height.

As shown in FIG. 14A, in a plan view of the surface of the galvanized layer 10 ', a minute recessed region 200 ' of 1 μm × 1 μm centered on each of the defined recessed bottom points PREk ' (k is 1 to 10) is specified. In fig. 14A, the longitudinal direction of the fine recessed region 200 ' is parallel to the extending direction RD ' of the texture 10S ', and the lateral direction of the fine recessed region 200 ' is parallel to the width direction WD '. However, as long as the fine recessed region 200 'is a plane including the extending direction RD' and the width direction WD ', each side of the fine recessed region 200' may not be parallel to the extending direction RD 'or the width direction WD'.

Similarly, as shown in FIG. 14B, a fine convex region 300 ' of 1 μm × 1 μm centered on each of the defined convex peaks PCOk ' (k is 1 to 10) is specified in a plan view of the surface of the galvanized layer 10 '. In fig. 14B, the vertical direction of the fine-projection region 300 ' is parallel to the extending direction RD ' of the texture 10S ', and the horizontal direction of the fine-projection region 300 ' is parallel to the width direction WD '. However, as long as the minute convex region 300 'is a plane including the extending direction RD' and the width direction WD ', each side of the minute convex region 300' may not be parallel to the extending direction RD 'or the width direction WD'.

The three-dimensional average roughness Sa ' was measured in the 10 minute recessed regions 200 ' and the 10 minute projecting regions 300 ' specified by the above method. The three-dimensional average roughness Sa' is an arithmetic average height specified in ISO 25178 obtained by expanding Ra (arithmetic average height of line) specified in JIS B0601(2013) to a surface. The arithmetic average of the 20 measured three-dimensional average roughness Sa 'was defined as the three-dimensional average roughness Saave'. In this case, the arithmetic average roughness Saave' is more than 5nm and 200nm or less.

Fine irregularities of nanometer order (hereinafter referred to as fine irregularities) caused by zinc-plated crystals are present in the vicinity of the peaks of the projections or in the vicinity of the bottoms of the recesses of the texture 10S'. If the minute unevenness has a certain size, light is diffusely reflected by the minute unevenness. In this case, the gloss of the texture is reduced, and the texture is whitened. Therefore, if a colored resin layer is formed on the galvanized layer, the texture becomes difficult to be visually confirmed. Therefore, from the viewpoint of further improving the visibility of the texture, it is preferable that the minute irregularities in the minute regions 200 'and 300' be as small as possible.

In embodiment 2, the three-dimensional average roughness Saave' based on the definition is greater than 5nm and 200nm or less. If the three-dimensional average roughness Saave' is 200nm or less, diffuse reflection of light in the vicinity of the apex of the convex portion and the vicinity of the base of the concave portion can be further suppressed. In this case, in the plated steel sheet 1 ' of embodiment 2 having the colored resin layer 11 ', the grain 10S ' becomes more easily visually recognized. The smaller the three-dimensional average roughness Saave' is, the more preferable it is. However, it is extremely difficult to make the three-dimensional average roughness Saave' 5nm or less. Therefore, in embodiment 2, the three-dimensional average roughness Saave' is greater than 5nm and 200nm or less. The preferable upper limit of the three-dimensional average roughness Saave' is 190nm, more preferably 180nm, and still more preferably 170 nm.

[ concerning element (B') ]

Referring to fig. 9, a cross section in a range of an arbitrary length of 100 μm in a direction WD ' perpendicular to the extending direction RD ' of the texture 10S ' is focused. The section (fig. 9) in the range of the length of 100 μm was defined as an observation section. In the observation cross section, the minimum thickness among the thicknesses of the colored resin layer 11 'is defined as DKmi n' (μ). In the observation cross section, the maximum thickness among the thicknesses of the colored resin layer 11 'is defined as DKmax' (μm).

Further, in the observation cross section, the content (area%) of the colorant in the colored resin layer 11 'is defined as CK'. As described above, in the present specification, the colorant content CK' is expressed as an area ratio (area%) of the colorant in the observation section.

As described above, in defining the minimum thickness DKmin ' (μm), the maximum thickness DKmax ' (μm), and the colorant content CK ' (area%) of the colored resin layer 11 ', the minimum thickness DKmin ' of the colored resin layer 11 ' and the content CK ' of the colorant 32 ' satisfy formula (1 ').

DKmin’×CK’≤15.0(1’)

If formula (1 ') is not satisfied, that is, if the product of the minimum thickness DKmin ' and the colorant content CK ' is more than 15.0, the thickness of the colored resin layer 11 ' is excessively thick or the colorant content CK ' is excessively large. In this case, the coloring of the colored resin layer 11 ' is excessively concentrated, and the texture 10S ' of the galvanized layer 10 ' is difficult to be visually confirmed. If the product of the minimum thickness DKmin ' and the colorant content CK ' is 15.0 or less, the texture 10S ' on the surface of the galvanized layer 10 ' can be sufficiently visually confirmed while having an appearance colored by the colored resin layer 11 ' on condition that the requirement (a ') and the requirement (C ') are satisfied. The upper limit of DKmin 'xck' is preferably 14.0, more preferably 13.0, and still more preferably 12.0. The lower limit of DKmin '× CK' is not particularly limited. The lower limit of DKMin '. times.CK' is, for example, 4.0.

The thickness of the colored resin layer 11' in embodiment 2 is measured by the following method. A sample was taken having a cross section perpendicular to the extension direction RD 'of the texture 10S' on the surface. An observation cross section in a range having a length of 100 μm in a direction WD ' perpendicular to an extending direction RD ' of the texture 10S ' in the sample was observed with a Scanning Electron Microscope (SEM) at 2000-fold reflected electron image (BSE). In the observation of the reflected electron image (BSE) using a Scanning Electron Microscope (SEM), the base steel sheet 100 ', the galvanized layer 10 ', and the colored resin layer 11 ' can be easily distinguished by contrast. In the observation cross section, the thickness of the colored resin layer 11 'was measured at a pitch of 0.5 μm in the direction WD'. The smallest thickness among the measured thicknesses was defined as a minimum thickness DKmin' (μm). The largest thickness among the measured thicknesses was defined as the maximum thickness DKmax' (μm). If it is necessary to determine whether or not the resin layer is a colored resin layer 11 '(that is, whether or not the resin contains a colorant), whether or not the resin layer is a colored resin layer 11' can be determined by TEM observation described later.

The colorant content CK '(area%) in the colored resin layer 11' is determined by the following method. A sample is taken having a cross section perpendicular to the direction RD 'of extension of the texture 10S' on the surface. Mixing the texture in the sampleA cross section perpendicular to the extending direction RD 'of 10S' is defined as an observation plane. A film sample capable of observing the colored resin layer 11 'and the zinc plating layer 10' on the observation surface was prepared from the sample using a Focused Ion Beam apparatus (FIB: Focused Ion Beam). The thickness of the film sample is set to 50 to 200 nm. On the observation surface of the prepared film sample, a Transmission Electron microscope (TEM: Transmission Electron microscope) was used to observe a field having a length of 3 μm in the direction perpendicular to the thickness direction of the colored resin layer 11 ' (i.e., direction WD ') and a length including the entire colored resin layer 11 ' in the thickness direction of the colored resin layer 11 ' (i.e., direction TD '). In TEM observation, the resin 31 ' and the colorant 32 ' in the colored resin layer 11 ' can be identified by contrast. The total area A1 ' (μm) of the plurality of colorants 32 ' in the colored resin layer 11 ' in the field of view was determined²). Then, the area a0 '(μm) of the colored resin layer 11' in the field of view was determined²). Based on the total area a1 ' and the area a0 ' obtained, the content (% by area) of the colorant in the colored resin layer 11 ' is obtained by the following equation.

CK＝A1’/A0’×100

[ concerning the requirement (C') ]

In an observation cross section in a range of a length of 100 μm in a direction WD 'perpendicular to an extending direction RD' of the texture 10S ', wherein the observation cross section is a cross section perpendicular to the extending direction RD' of the texture 10S ', a maximum thickness DKmax' of the colored resin layer 11 ', a minimum thickness DKmin' of the colored resin layer 11 ', and a content CK' of the colorant 32 'satisfy formula (2').

(DKmax’-DKmin’)×CK’>1.0 (2’)

(DKmax '-DKmin'). times.CK 'is an index of the contrast of lightness in the colored resin layer 11'. If (DKmax '-DKmin'). times.CK 'is 1.0 or less, the contrast of brightness in the colored resin layer 11' is low. In this case, the contrast of the lightness of the colored resin layer 11 'cannot be sufficiently utilized for visual confirmation of the texture 10S'. Therefore, the texture 10S 'under the colored resin layer 11' is difficult to be visually confirmed.

If (DKmax '-DKmin'). times.CK 'is higher than 1.0, the contrast of lightness in the colored resin layer 11' is sufficiently high. In this case, the contrast of the lightness of the colored resin layer 11 'can be sufficiently utilized for visual confirmation of the texture 10S'. As a result, the grain 10S 'under the colored resin layer 11' can be sufficiently visually confirmed on the premise that the requirements (a ') and (B') are satisfied.

The lower limit of (DKmax ' -DKmin '). times.CK ' is preferably 1.2, more preferably 1.5, still more preferably 1.8, and yet more preferably 2.0. The upper limit of (DKmax ' -DKmin '). times.CK ' is not particularly limited. The upper limit of (DKmax ' -DKmin '). times.CK ' is, for example, 15.0.

[ thickness of colored resin layer 11' ]

In the plated steel sheet 1 'according to embodiment 2, the average thickness of the colored resin layer 11' is preferably 10.0 μm or less. If the thickness of the colored resin layer 11 'exceeds 10.0 μm, it is easy to smooth (level) only the colored resin layer 11', and the difference between the impression of reflection at the surface of the colored resin layer 11 'and the impression of the texture 10S' that can be visually confirmed becomes large. In this case, the metallic feeling of the plated steel sheet 1' is reduced. If the average thickness of the colored resin layer 11 ' is 10.0 μm or less, the texture 10S ' of the galvanized layer 10 ' can be visually confirmed and the metallic feeling can be sufficiently improved on the premise that all the requirements (a ') to (C ') described above are satisfied. The upper limit of the average thickness of the colored resin layer 11' is more preferably 9.0 μm, and still more preferably 8.0 μm.

Further, a preferable lower limit of the average thickness of the colored resin layer 11' is 0.5 μm. If the average thickness of the colored resin layer 11' is 0.5 μm or more, the corrosion resistance is further improved. A more preferable lower limit of the average thickness of the colored resin layer 11' is 0.7 μm, more preferably 1.0 μm, more preferably 2.0 μm, and more preferably 3.0 μm.

The average thickness of the colored resin layer 11' is measured by the following method. The arithmetic average of the thicknesses measured at a pitch of 0.5 μm in the direction WD 'in the above-described observation section is defined as the average thickness (μm) of the colored resin layer 11'.

[ other forms of the colored resin layer 11' ]

The colored resin layer 11 ' of the plated steel sheet 1 ' according to embodiment 2 may contain an additive for further imparting corrosion resistance, sliding properties, conductivity, and the like to the colored resin layer 11 '. Examples of the additive for imparting corrosion resistance include known rust inhibitors and inhibitors. Examples of additives for imparting slidability are well-known waxes and beads. Examples of the additive for imparting conductivity are known conductive agents.

[ regarding the surface shape of the preferable colored resin layer 11 '(regarding the requirement (D') ]

It is preferable that the colored resin layer 11 ' has a surface shape as described in detail below due to the kind of texture 10S ' formed on the surface of the galvanized layer 10 ' as the lower layer.

The surface roughness Ra of the colored resin layer 11 'in the extending direction RD' of the texture 10S 'is defined as Ra (cl)'. When the texture 10S 'is a hair line, the surface roughness Ra of the colored resin layer 11' in the direction WD 'perpendicular to the extending direction RD' of the texture 10S 'is defined as Ra (cc)'. At this time, it is preferable that the surface roughness ra (cc) ' and the surface roughness ra (cl) ' satisfy the formula (3 ').

Ra(CC)’≥Ra(CL)’×1.10(3’)

If the surface roughness ra (cc) 'of the colored resin layer 11' is less than 1.10 times with respect to the surface roughness ra (cl) 'then the difference between the impression given by the texture 10S' in the state of the non-colored resin layer 11 'and the impression of reflection of light at the surface of the colored resin layer 11' becomes excessively large. In this case, the metallic feeling is lost. If the surface roughness ra (cc) ' is 1.10 times or more with respect to the surface roughness ra (cl) ' it is possible to suppress the difference between the impression given by the texture 10S ' in the state of the non-colored resin layer 11 ' and the impression of reflection of light at the surface of the colored resin layer 11 '. Therefore, a sufficient metallic feeling can be obtained. The surface roughness ra (cc) ' of the colored resin layer 11 ' is preferably 1.15 times or more, more preferably 1.20 times or more, and still more preferably 1.25 times or more the surface roughness ra (cl) '.

The surface roughness ra (cl)' was measured by the method for measuring arithmetic average roughness specified in JIS B0601 (2013). Specifically, any 10 positions on the surface 11S 'of the colored resin layer 11' are measured positions. At each measurement position, the arithmetic average roughness Ra is measured at an evaluation length extending in the extending direction RD 'of the texture 10S'. The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a stylus type roughness meter at a rate of 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cl)'.

Similarly, the surface roughness ra (cc)' was measured by the method for measuring arithmetic average roughness specified in JIS B0601 (2013). Specifically, 10 arbitrary positions are set as measurement positions on the surface 11S 'of the colored resin layer 11'. At each measurement position, the arithmetic average roughness Ra is measured at an evaluation length extending in a direction WD ' perpendicular to the extending direction RD ' of the texture 10S '. The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a stylus type roughness meter at a rate of 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cc)'.

[ regarding the surface shape of the galvanized layer 10 '(regarding the requirement (E')) ]

The surface roughness Ra in the direction WD ' perpendicular to the extending direction of the texture 10S ' of the surface of the galvanized layer 10 ' on which the texture 10S ' is formed is defined as Ra (mc) '. When the texture 10S 'is a hair line, the surface roughness Ra (MC)' is preferably 0.30 μm or more. If the surface roughness ra (mc) ' is less than 0.30 μm, the texture 10S ' is difficult to be visually recognized from above the colored resin layer 11 '. If the surface roughness ra (mc) ' is 0.30 μm or more, the texture 10S ' can be sufficiently visually recognized from above the colored resin layer 11 '. The lower limit of the surface roughness Ra (MC)' is more preferably 0.35. mu.m, and still more preferably 0.40. mu.m. The upper limit of the surface roughness ra (mc)' is not particularly limited. However, it is sometimes difficult to industrially produce the steel sheet with an excessively high surface roughness ra (mc)' or the like. Therefore, the upper limit of the surface roughness Ra (MC)' is, for example, 2.00. mu.m. The upper limit of the surface roughness ra (mc)' may be, for example, 1.00 μm.

The surface roughness ra (mc)' was measured by the method for measuring arithmetic average roughness specified in JIS B0601 (2013). Specifically, the colored resin layer 11 ' of the plated steel sheet 1 ' is removed with a solvent or a remover (for example, a product name: Neo Rever S-701 manufactured by Sanko chemical Co., Ltd.) which does not attack the galvanized layer 10 '. In the texture 10S ' of the galvanized layer 10 ' after the colored resin layer 11 ' was removed, 10 arbitrary positions were set as measurement positions. At each measurement position, the arithmetic average roughness Ra is measured at an evaluation length extending in a direction WD ' perpendicular to the extending direction RD ' of the texture 10S '. The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a stylus type roughness meter at a rate of 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (mc)'.

[ Exposure of base Steel sheet ]

The galvanized layer 10 'of the plated steel sheet 1' preferably has a base steel sheet exposure of less than 5%. In embodiment 2, the corrosion resistance is sufficiently ensured by the galvanized layer 10' (galvanized or zinc alloy plated). However, if the surface of the galvanized layer 10 'is ground when the texture 10S' is imparted, and as a result, the base steel sheet is exposed, the long-term corrosion resistance (long-term corrosion resistance) may be reduced due to the influence of galvanic corrosion. Such a decrease in long-term corrosion resistance is often remarkable when the base steel sheet exposure rate is 5% or more. Therefore, in embodiment 2, the base steel sheet exposure is preferably less than 5%.

If the base steel sheet exposure of the galvanized layer 10' is less than 5%, excellent corrosion resistance can be obtained even for a long period of time in addition to appropriate corrosion resistance required for general steel materials. The upper limit of the base steel sheet exposure of the galvanized layer 10' is preferably 3% or less, more preferably 2%, even more preferably 1%, and even more preferably 0%.

The base steel sheet exposure was measured by the following method. Specifically, the colored resin layer 11 ' of the plated steel sheet 1 ' is removed with a solvent or a remover (for example, a product name: Neo Rever S-701 manufactured by Sanko chemical Co., Ltd.) which does not attack the galvanized layer 10 '. In the surface of the galvanized layer 10', 5 rectangular areas of 1mm × 1mm are arbitrarily selected. EPMA analysis was performed on the selected rectangular area. By image analysis, a region in which Zn is not detected (Zn undetected region) is specified among the rectangular regions. In embodiment 2, a region in which the Zn detection intensity is not more than 1/16 of the intensity when the standard sample (pure Zn) is measured is regarded as a Zn non-detection region. The proportion (% by area) of the total area of the Zn-unmeasured regions in 5 rectangular regions with respect to the total area of the 5 rectangular regions was defined as the base steel sheet exposure rate (% by area).

In addition, the plated steel sheet 1 ' according to embodiment 2 may have an inorganic coating or an organic-inorganic composite coating formed between the colored resin layer 11 ' and the galvanized layer 10 ' for the purpose of improving corrosion resistance or adhesion. The inorganic film has light transmittance. The inorganic coating is, for example, an amorphous silica coating, a zirconia coating, or a phosphate coating. The organic-inorganic composite coating has light transmittance. The organic-inorganic composite coating film contains, for example, a silane coupling agent and an organic resin. The organic-inorganic composite coating has light transmittance.

[ production method ]

An example of the method for producing the plated steel sheet 1' of embodiment 2 will be described below. The manufacturing method described below is an example for manufacturing the plated steel sheet 1' according to embodiment 2. Therefore, the plated steel sheet 1' having the above-described configuration can be manufactured by a manufacturing method other than the manufacturing method described below. However, the manufacturing method described below is a preferred example of the manufacturing method of the plated steel sheet 1' according to embodiment 2.

The manufacturing method of embodiment 2 includes: a step of preparing a base steel sheet 100 ' (preparation step S1 '), a step of forming a galvanized layer 10 ' on the base steel sheet 100 ' (galvanizing step S2 '), a step of forming a texture on the surface of the galvanized layer 10 ' (texture processing step S3 '), and a step of forming a colored resin layer 11 ' on the plated steel sheet (colored resin layer forming step S4 '). Hereinafter, each step will be explained.

[ preparation Process (S1') ]

In the preparation step (S1 '), the base steel sheet 100' is prepared. The base steel plate 100' may be a steel plate or may have another shape. If the base steel sheet 100 'is a steel sheet, the base steel sheet 100' may be a hot-rolled steel sheet or a cold-rolled steel sheet.

[ Zinc plating Process (S2') ]

In the galvanizing process (S2 '), the prepared base steel sheet 100' is galvanized to form a galvanized layer 10 'on the surface of the base steel sheet 100'.

The zinc plating treatment may be performed by a known method. For example, the galvanized layer 10' may be formed using a well-known electroplating method. In this case, as the zinc plating bath and the zinc alloy plating bath, known baths may be used. Examples of the plating bath 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, combinations thereof, and the like. The zinc alloy plating bath contains, for example, 1 or more kinds of single ions or complex ions selected from Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, and Zr in addition to Zn ions.

The chemical composition, temperature, flow rate, and conditions (current density, energization pattern, and the like) during the plating treatment of the zinc plating bath and the zinc alloy plating bath in the zinc plating treatment can be appropriately adjusted. The thickness of the galvanized layer 10' in the zinc plating treatment can be adjusted by adjusting the current value and time within the range of the current density at the time of the zinc plating treatment.

The galvanized layer 10' may also be formed by a hot-dip galvanizing process or an alloying hot-dip galvanizing process. In this case, a known zinc plating bath is also prepared. The zinc plating bath may contain, for example, Zn as a main component and 1 or more elements selected from Mg, Al, and Si. If the galvanized layer 10 'is a hot-dip galvanized layer, the base steel sheet 100' is immersed in a galvanizing bath whose bath temperature and bath chemical composition are adjusted, and the galvanized layer 10 '(hot-dip galvanized layer) is formed on the surface of the base steel sheet 100'. In addition, if the galvanized layer 10 ' is an alloyed hot-dip galvanized layer, the base steel sheet 100 ' on which the hot-dip galvanized layer is formed is subjected to a known heat treatment in a known alloying furnace, and the galvanized layer 10 ' is made into an alloyed hot-dip galvanized layer. The thickness of the galvanized layer 10' in the hot-dip galvanizing treatment can be adjusted by adjusting the immersion time of the galvanizing bath and the amount of galvanized removed by gas wiping. The base steel sheet 100' may be subjected to a known degreasing treatment such as electrolytic degreasing before the plating treatment.

Through the above manufacturing steps, a plated steel sheet 1 ' including the base steel sheet 100 ' and the galvanized layer 10 ' can be manufactured.

[ texturing Process (S3') ]

In the texturing step (S3 '), the surface of the galvanized layer 10' of the plated steel sheet is subjected to known texturing to form a texture 10S 'on the surface of the galvanized layer 10'.

If the texture 10S' is a hairline, a well-known hairline process is performed. Examples of methods for processing hair line include: a method of forming hair lines by polishing the surface with a known polishing tape, a method of forming hair lines by polishing the surface with a known polishing brush, a method of forming hair lines by roll transfer with a roller having a hair line shape, and the like. The length, depth, and frequency of the hair line can be adjusted by adjusting the particle size of a known polishing tape, the particle size of a known abrasive brush, or the surface shape of a roller. That is, the arithmetic average roughness ra (mc)' and the base steel sheet exposure rate can be adjusted by adjusting the grain size of a known polishing tape, the grain size of a known polishing brush, or the surface shape of a roll. As a method of imparting hair lines, it is preferable to form hair lines by polishing the surface with a polishing tape or a polishing brush from the viewpoint of surface quality. In this manufacturing method, since the step of forming the texture on the surface of the base material is not included and the surface of the base material does not have the texture, the plating surface before the texture processing step (S3') is started is relatively flat. Therefore, the recesses of the texture are formed by polishing or the like in the texture processing step (S3'). At this time, the concave portions are formed so that the three-dimensional average roughness Saave' is greater than 5nm and 200nm or less.

Through the above manufacturing steps, a plated steel sheet 1 ' including the base steel sheet 100 ' and the galvanized layer 10 ' and having the texture 10S ' extending in one direction formed on the surface of the galvanized layer 10 ' can be manufactured.

[ colored resin layer Forming step (S4') ]

In the colored resin layer forming step (S4 '), the colored resin layer 11' is formed on the galvanized layer 10 'of the plated steel sheet having the grain 10S' formed thereon. The coloring resin layer forming step (S4') will be described in detail below.

The paint used for forming the colored resin layer 11' preferably follows the surface shape of the steel material immediately after being applied to the plated steel sheet, and after once reflecting the surface shape of the steel material, the paint is slowly leveled. That is, it is preferable that the viscosity is low if the shear rate is high, and the viscosity is high if the shear rate is low. Specifically, it is preferable that the viscosity is 10[ Pa · s ] or more at a shear rate of 0.1[1/sec ], and the viscosity is 0.01[ Pa · s ] or less at a shear rate of 1000[1/sec ].

The surface shape of the colored resin layer 11 'can be adjusted by adjusting the shear viscosity of the paint used for forming the colored resin layer 11'.

The method of forming the colored resin layer 11 'on the galvanized layer 10' may be a well-known method. For example, the coating material whose viscosity is adjusted is applied to the zinc plating layer 10' by a spray coating method, a roll coating method, a curtain coating method, or a dip coating method. Then, the paint on the galvanized layer 10 'is naturally dried or baked to be dried to form a colored resin layer 11'. The drying temperature, drying time, baking temperature and baking time can be adjusted appropriately. The three-dimensional average roughness Saave ', the minimum thickness DKmin' and the maximum thickness DKmax 'of the colored resin layer 11' can be adjusted by adjusting the shear viscosity of the paint used in the formation of the colored resin layer 11 'and the coating amount on the galvanized layer 10'. Further, by adjusting the content of the colorant in the paint, the colorant content CK 'in the colored resin layer 11' can be adjusted.

Through the above manufacturing steps, the plated steel sheet 1' according to embodiment 2 can be manufactured. The plated steel sheet 1 ' according to embodiment 2 is not limited to the above-described manufacturing method, and the plated steel sheet 1 ' according to embodiment 2 may be manufactured by a manufacturing method other than the above-described manufacturing method as long as the plated steel sheet 1 ' having the above-described configuration can be manufactured. However, the above-described manufacturing method is suitably used for manufacturing the plated steel sheet 1' according to embodiment 2.

Although embodiment 1 and embodiment 2 of the present invention have been described above, the configuration of embodiment 1 and the configuration of embodiment 2 may be combined as appropriate. The specific embodiments exemplified in the description of embodiment 1 can be applied to the plated steel sheet of embodiment 2, and vice versa.

In the plated steel sheet 1 according to embodiment 1 and the plated steel sheet 1' according to embodiment 2 of the present invention, the colored resin layer may be a laminated resin layer. This can further improve the visibility of the surface of the galvanized layer and suppress the change in color tone. This is because the colored resin layer is a laminated resin layer, and thus local thickness variation of the colored resin layer can be suppressed. The variation in thickness is related to the variation in the concentration of the colorant (pigment). Therefore, by suppressing the variation in thickness, the variation in the concentration of the coloring material can be suppressed, and the variation in color tone can be suppressed.

Further, the content CK of the coloring material in each colored resin layer may be adjusted_NAnd thickness DK_NThe sum of the products of (a) and (b) is 15.0 area%. mu.m or less. Namely, the content CK of the coloring material in each colored resin layer_NAnd thickness DK_NThe following formula can be satisfied.

Σ[k＝1→n](CK_k×DK_k)≤15.0

Thus, the laminated resin layer can be colored to such an extent that the surface of the galvanized layer can be visually confirmed. Further, the visibility of the surface of the zinc-plated layer can be further improved, and the color tone variation such as color unevenness and color fluctuation can be sufficiently suppressed. Content CK of coloring material in each colored resin layer_NAnd thickness DK_NThe upper limit of the sum of the products of (a) is preferably 12.0 area%. mu.m, 10.0 area%. mu.m or 8.0 area%. mu.m.

Further, the content (area%) of the colorant of the most intensely colored resin layer is defined as "C_1ST", the thickness (. mu.m) of the most intensely colored resin layer was defined as" D_1ST", the content (area%) of the coloring material in the 2 nd dark colored resin layer was defined as" C_2ND", the thickness (. mu.m) of the 2 nd dark-colored resin layer was defined as" D_2NDIn the case of "the laminated resin layer", the following formula (4) can be satisfied.

1.00<(C_1ST×D_1ST)/(C_2ND×D_2ND)≤4.00 (4)

That is, the color density index I of the most intensely colored resin layer_1ST(＝C_1ST×D_1ST) Color density index I of 2 nd color-rich colored resin layer_2ND(＝C_2ND×D_2ND) The ratio of (d) may be 4.00 or less. The following (C)_1ST×D_1ST)/(C_2ND×D_2ND) Referred to as "color density ratio RF".

If the color density ratio RF is 4.00 or less, the difference between the color density of the most dense colored resin layer and the color density of the 2 nd dense colored resin layer is not large. Therefore, when the resin layer is colored to such an extent that the surface of the galvanized layer can be visually confirmed, and color variation such as color unevenness and color fluctuation can be sufficiently suppressed.

The upper limit of the color density ratio RF is preferably 3.80, more preferably 3.50, more preferably 3.00, more preferably 2.50, and more preferably 2.00. The closer the color density ratio RF is to 1.00, the more preferable. Therefore, the lower limit of the color density ratio RF is more than 1.00. In addition, if the multilayer colored resin layer LK contains a plurality of types of colorants having different hues, the RF may be 4.00 or less for each colorant having the same hue.

The thickness (total thickness) of the laminated resin layers is not particularly limited, and may be, for example, 10.0 μm or less. If the thickness of the laminated resin layer is 10.0 μm or less, the surface of the galvanized layer can be visually confirmed even if the laminated resin layer is colored to such an extent that the surface of the galvanized layer can be visually confirmed, and the metallic feeling can be sufficiently improved while color variations such as color unevenness and color fluctuation can be sufficiently suppressed, on the premise that the above requirements are satisfied. The upper limit of the thickness of the laminated resin layer is more preferably 9.0. mu.m, and still more preferably 8.0. mu.m.

Further, the lower limit of the laminated resin layer is preferably 0.5 μm. If the laminated resin layer is 0.5 μm or more, the corrosion resistance is further improved. The lower limit of the laminated resin layer is more preferably 0.7. mu.m, still more preferably 1.0. mu.m, yet more preferably 2.0. mu.m, yet more preferably 3.0. mu.m.

The laminated resin layer 30 may be formed by laminating 1 or more transparent resin layers containing no colorant between a plurality of colored resin layers. The "transparent resin layer" contains a resin having light transmittance and containing no colorant. The resin having light transmittance means that the surface of the base steel sheet can be visually confirmed when a design galvanized steel sheet having a laminated resin layer including a colored resin layer containing a coloring agent and a resin and a transparent resin layer is placed in an environment corresponding to sunlight (illuminance of about 65000 lux) on a sunny day at noon. The order of lamination of the colored resin layer and the transparent resin layer is not particularly limited. In the laminated resin layer, a plurality of transparent resin layers may be continuously laminated.

Examples

(example 1)

Hereinafter, the effects of one mode of the present invention will be described in further detail by examples. The conditions in the following examples are one example of conditions adopted to confirm the feasibility and effects of the implementation of the plated steel sheet 1 according to embodiment 1 of the present invention. Therefore, the present invention is not limited to this conditional example. Various conditions can be adopted in the present invention within the range where the object of the present invention can be achieved without departing from the gist of the present invention.

Galvanized steel sheets of test numbers shown in table 1 were prepared. The base steel sheet of each galvanized steel sheet was SPCC defined in JI S G3141 (2017), and the thickness was 0.6 mm.

The base material surface texture forming step is performed on each base material steel sheet, and base material textures (hairline or matte) of various forms are formed on the base material surface. In test nos. 1, 18, 23, and 28, no texture was formed on the surface of the base material. The column "base material texture" in table 1 shows the presence or absence of the base material surface texture forming step and the type of the base material surface texture forming step in each test number.

Each base steel sheet was subjected to plating pretreatment. Specifically, Na was used at a concentration of 30g/L for each steel material₄SiO₄The treating liquid has a temperature of 60 deg.C and a current density of 20A/dm²Electrolytic degreasing was performed for 10 seconds, and water washing was performed. Immersing the electrolytically degreased steel in H with the concentration of 50g/L at 60 DEG C₂SO₄The aqueous solution was left for 10 seconds and washed with water.

The steel sheets of the respective test numbers after the plating pretreatment were subjected to the following plating treatment to form zinc plating layers. Specifically, in test nos. 1 to 17, zinc plating layers were formed by electroplating. Specifically, a plating bath containing 1.0mol/L of zinc sulfate heptahydrate and 50g/L of anhydrous sodium sulfate and having a pH adjusted to 2.0 was prepared. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc plating layer (indicated by "EG" in the column of "plating type" in table 1) was formed.

In test Nos. 18 to 22, zinc plating layers containing Ni were formed as the zinc plating layers. Specifically, a plating bath adjusted to pH 2.0 containing zinc sulfate heptahydrate and nickel sulfate hexahydrate in a total amount of 1.2mol/L and further containing anhydrous sodium sulfate 50g/L was prepared. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc plating layer (indicated by "Zn — 12% Ni" in the column of "plating type" in table 1) containing 12% by mass of Ni and the remainder consisting of Zn and impurities was formed.

In test Nos. 23 to 27, zinc plating layers containing Fe were formed as the zinc plating layers. Specifically, a plating bath containing 1.2mol/L of zinc sulfate heptahydrate and iron (II) sulfate heptahydrate in total and further containing 50g/L of anhydrous sodium sulfate and having a pH adjusted to 2.0 was prepared. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc plating layer (indicated by "Zn — 14% Fe" in the column of "plating type" in table 1) containing 14% by mass of Fe and the remainder consisting of Zn and impurities was formed.

In test nos. 28 to 32, a zinc plating layer containing Co was formed as a zinc plating layer. Specifically, a zinc sulfate heptahydrate and a cobalt sulfate hexahydrate containing 1.2mol/L in total and anhydrous sulfuric acid were preparedSodium 50g/L plating bath with pH adjusted to 2.0. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc plating layer (represented by "Zn — 2% Co" in the column of "plating type" in table 1) containing 2% by mass of Co and the remainder consisting of Zn and impurities was formed.

In the plating treatment of each test number, the plating solution was flowed so that the relative flow rate was 1 m/sec. The composition of the obtained zinc plating layer was measured by the following method. The steel sheet on which the plating layer was formed was immersed in 10 mass% hydrochloric acid to which a suppressor (No. 700AS, manufactured by shinkanji chemical) was added, and the zinc plating layer was dissolved and peeled off. Then, ICP analysis was performed on the solution in which the zinc plating layer was dissolved to confirm the composition of the zinc plating layer.

After the formation of the galvanized layer, the galvanized surface texture formation step was performed in test nos. 2 to 4, 6 to 17, 19 to 22, 24 to 27, and 29 to 32, and further the polishing step was performed, and the top end of the convex portion of the galvanized layer was ground and polished. In the galvanized surface texture forming step and the polishing step, polishing tapes having various particle sizes were pressed against the tips of the convex portions of the galvanized layer, and the pressing force and the number of times of polishing were changed to perform grinding and polishing. In the step of forming the texture on the galvanized surface, a polishing tape having a particle size coarser than that in the step of grinding is used. In test nos. 1, 5, 18, 23, and 28, the galvanized surface texture forming step and the polishing step were not performed. In the column of "plating texture" in table 1, the presence or absence of the plating surface texture forming step and the type of the plating surface texture forming step in each test number are shown.

Note that even a plated steel sheet obtained without going through the galvanization surface texture forming step has a plating texture as long as the base material texture is formed through the base material surface texture forming step. This is because if a galvanized layer is formed by galvanizing a base steel sheet having a base texture, a plated texture along the base texture is formed on the surface of the galvanized layer. For example, the plated steel sheet of test No. 5 was manufactured without undergoing the galvanized surface texture forming step. Therefore, test No. 5 is described as "none" in the column of "plating texture" in table 1. However, the plated steel sheet of test No. 5 was produced through the base material surface texture forming step, and therefore had a plated texture.

A colored resin layer was formed on each of the galvanized steel sheets with hairlines (test Nos. 2 to 17, 19 to 22, 24 to 17, and 29 to 32) and the galvanized steel sheets without hairlines (test Nos. 1, 18, 23, and 28). In the colored resin layer, as an organic resin, a paint having various concentrations and viscosities was prepared in which a urethane resin (HUX-232, manufactured by ADEK a) was dispersed in water. Pigments (carbon black) were added to the coating at various concentrations. The carbon black was used under the trade name #850 manufactured by Mitsubishi chemical corporation.

The coating material was applied to the surface of the zinc coating layer of each test-number galvanized steel sheet by dipping it with a roller. The coated paint was baked and dried. Specifically, the galvanized steel sheet coated with the paint was charged into a furnace maintained at 250 ℃. The galvanized steel sheet is kept in the furnace for 1 to 5 minutes until the arrival temperature of the galvanized steel sheet reaches 210 ℃. After the holding, the galvanized steel sheet was taken out of the furnace and cooled.

The viscosity of the coating material was adjusted using a viscosity adjuster (product name: BYK-425, manufactured by BYK). Specifically, the viscosity of the coating material is adjusted so that the coating material viscosity is 10(Pa · s) or more at a shear rate of 0.1(1/sec) and 0.01(Pa · s) or less at a shear rate of 1000 (1/sec). Through the above steps, a colored resin layer was formed on the galvanized layer of each test number.

By the above-described manufacturing method, galvanized steel sheets of the respective test numbers were manufactured. In test No. 18, a urethane resin (HUX-232, manufactured by ADEKA) having no pigment was applied between the colored resin layer and the zinc-plated layer in an amount of 0.5 μm. Then, a colored resin layer was formed.

[ evaluation test ]

[ measurement tests for three-dimensional average roughness Sas at the bottom of a concave portion and three-dimensional average roughness Sah at the top of a convex portion ]

The maximum three-dimensional average roughness of the texture (hairline) on the galvanized layer surface of each test-numbered galvanized steel sheet was measured by the following method. First, the colored resin layer of the galvanized steel sheet was removed by using a solvent (trade name: Neolever S-701, manufactured by Sanko chemical Co., Ltd.) which did not attack the galvanized layer. In the surface of the galvanized layer, 1 range having a length of 1000 μm is arbitrarily selected in the 2 nd direction perpendicular to the extending direction (1 st direction) of the texture (hairline). The roughness profile of the texture was measured over a selected length of 1000 μm. The roughness profile was measured using a three-dimensional surface roughness measuring machine (SURFCOM 1500DX3, precision, tokyo).

Attention is paid to each concave portion 10RE in the roughness profile obtained by the measurement. In each recess 10RE, the position with the lowest height is defined as a recess bottom point PRE. Among a plurality of recess bottom points PRE in the roughness profile in the range of 1000 μm in length, 10 recess bottom points PRE1, PRE2, …, PRE10 are specified in order from the lowest recess bottom point PRE1, in descending order.

As shown in FIG. 6A, in a plan view of the surface of the galvanized layer, a minute recessed portion bottom area of 1 μm × 1 μm centered on each of the defined recessed portion bottom points PREk (k is 1 to 10) is specified. The three-dimensional average roughness Sa was measured for each of the 10 specified fine recessed portion bottom regions. The three-dimensional average roughness Sa is an arithmetic average roughness specified in ISO 25178, obtained by expanding Ra (linear arithmetic average roughness) specified in JIS B0601(2013) to a surface. The arithmetic average of the 10 measured three-dimensional average roughness Sa was defined as the three-dimensional average roughness Sas (μm) of the bottom of the dent.

Similarly, attention is paid to each convex portion 10CO in the roughness profile obtained by the measurement. In each convex portion 10CO, the position having the highest height is defined as a convex portion apex PCO. Among the plurality of projection apexes PCO in the roughness profile having a length in the range of 1000 μm, 10 projection apexes PCO1, PCO2, …, PCO10 are designated in order from the highest projection apex PCO1 in height.

As shown in FIG. 6B, in a plan view of the surface of the zinc plating layer, a fine projection top region of 1 μm × 1 μm centered on each of the defined projection tops PCOk (k is 1 to 10) is specified. The three-dimensional average roughness Sa was measured for each of the 10 specified fine projection top regions. The three-dimensional average roughness Sa is an arithmetic average roughness specified in ISO 25178, obtained by expanding Ra (linear arithmetic average roughness) specified in JIS B0601(2013) to a surface. The arithmetic average of the 10 measured three-dimensional average roughness Sa was defined as the three-dimensional average roughness Sah (. mu.m) of the top of the protrusions.

[ DKMin and DKmax measurement tests ]

The thickness (DKmin, DKmax) of the colored resin layer of each test number galvanized steel sheet was measured by the following method. From each of the galvanized steel sheets of test numbers, a sample having a cross section perpendicular to the 1 st direction of the grain (hairline) on the surface was collected. An observation cross section in a range having a length of 100 μm in a direction perpendicular to the extending direction of the grain (hair line) in the sample was observed with a reflection electron image (BSE) of 2000 times using a Scanning Electron Microscope (SEM). In the observation cross section, the thickness of the colored resin layer was measured at a pitch of 0.5 μm in the direction WD. Among the thicknesses obtained by the measurement, the smallest thickness was defined as a minimum thickness DKmin (μm). Among the thicknesses obtained by the measurement, the maximum thickness was defined as the maximum thickness DKmax (μm).

[ measurement test for CK content of coloring agent ]

The content (area%) of the coloring agent in the colored resin layer of each test number galvanized steel sheet was determined by the following method. A sample having a cross section perpendicular to the 1 st direction of the texture (hairline) on the surface was taken. In the sample, a cross section perpendicular to the 1 st direction of the texture (hairline) was taken as an observation plane. A film sample capable of observing the colored resin layer and the zinc plating layer on the observation surface was prepared from the sample using FIB. The film thickness of the thin film sample was 150 nm. Using TEM, observation was performed on a film sample prepared having a length of 3 μm in the direction perpendicular to the thickness direction of the colored resin layer (i.e., 2 nd direction WD) and a field of view including the length of the entire colored resin layer in the thickness direction of the colored resin layer (i.e., 3 rd direction TD). In TEM observation, isThe resin and pigment in the color resin layer can be identified by contrast. The total area A1(μm) of the plurality of pigments in the colored resin layer in the observation cross section was obtained²). And the area (mum) of the colored resin layer in the observation cross section was determined²). Based on the total area a1 and the area a0 thus obtained, the content of the colorant (area%) in the colored resin layer 11 was obtained by the following equation.

CK＝A1/A0×100

[ measurement tests for Ra (CC) and Ra (CL) roughness of colored resin layer ]

The roughness ra (cc) and ra (cl) in the colored resin layer of each test-number galvanized steel sheet were determined by the following methods.

The surface roughness ra (cl) was measured by the arithmetic average roughness measurement method specified in JIS B0601 (2013). Any 10 positions on the surface of the colored resin layer were used as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured at an evaluation length extending in the 1 st direction of the texture (hair line). The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a three-dimensional surface roughness measuring instrument (SURFCOM 1500D X3, precision product of tokyo) at a measuring speed of 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cl).

Similarly, the surface roughness ra (cc) is measured by the arithmetic average roughness measurement method specified in JIS B0601 (2013). Any 10 positions on the surface of the colored resin layer were used as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured at an evaluation length extending in the 2 nd direction of the texture (hair line). The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using the three-dimensional surface roughness measuring instrument described above, and the measurement speed was set to 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cc).

[ surface roughness Ra (MC) measurement test of Zinc plating layer ]

The surface roughness ra (mc) of the zinc coating layer of each test number galvanized steel sheet was obtained by the following method.

The surface roughness ra (mc) is measured by the arithmetic average roughness measurement method specified in JIS B0601 (2013). The colored resin layer of the galvanized steel sheet was removed by using a solvent (trade name: Neolever S-701, manufactured by Sanko Co., Ltd.) which did not attack the galvanized layer. In the texture (hairline) of the galvanized layer after the colored resin layer was removed, arbitrary 10 positions were set as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured with an evaluation length extending in the 2 nd direction. The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using the three-dimensional surface roughness measuring instrument described above, and the measurement speed was set to 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (mc) (μm).

[ base Steel sheet Exposure Rate measurement test ]

The base steel sheet exposure of each test number galvanized steel sheet was measured by the following method. A galvanized steel sheet from which the colored resin layer was removed was prepared. In the surface of the galvanized layer, 5 rectangular areas of 1mm × 1mm were arbitrarily selected. EPMA analysis was performed on the selected rectangular area. By the image analysis, the region where Zn is not detected (Zn undetected region) among the rectangular regions is specified. A region where the Zn detection intensity is 1/16 or less, which is the intensity when the standard sample (pure Zn) is measured, is regarded as a Zn non-detection region. The proportion (% by area) of the total area of the Zn-unmeasured regions in 5 rectangular regions with respect to the total area of the 5 rectangular regions was defined as the base steel sheet exposure rate (% by area).

[ texture visual confirmation test ]

The galvanized steel sheets of each test number were placed in an environment corresponding to the sun light (illuminance of about 65000 lux) on the morning of a clear day. Then, the angles of the light source, the steel plate, and the line of sight were variously modified and observed to confirm whether or not the texture could be visually confirmed. The steel sheet was evaluated as a very good pass if the texture could be visually confirmed at all angles in the range of 5 ° to 80 ° in the perpendicular direction to the surface of the steel sheet (evaluation "a" in table 1). Further, if some of the textures were visually recognized at an angle in the range of 5 ° to 80 ° with respect to the perpendicular direction to the steel sheet surface, the evaluation was passed (evaluation "B" in table 1). On the other hand, if the texture could not be confirmed with the naked eye at all, the evaluation was failed ("C" evaluation in table 1).

[ lightness measurement test ]

The lightness L of each of the galvanized steel sheets of the test numbers was measured by the following method^*The value serves as a reference value. A color meter (trade name: CM-2600d) manufactured by Konika Minneta was used for the measurement. In the measurement, CIE standard illuminant D65 was used as a illuminant, the viewing angle was set to 10 °, and L was obtained by expressing color by CIELAB in SCI manner^*The value is obtained.

The CIE standard light source D65 is defined in JIS Z8720 (2000) "illuminant for color measurement (standard light) and standard light source", and is also defined in ISO 10526 (2007). CIE is an abbreviation for Co mmision International de l' Eclairage and represents the International Commission on illumination. The CIE standard illuminant D65 is used to represent the color of an object under daylight illumination. Regarding the viewing angle of 10 °, the same is specified in JIS Z8723 (2009) "visual comparison method of surface color", and ISO/DIS 3668.

The SCI method is also called a specular reflection light-containing method, and indicates a method for measuring a color without removing specular reflection light. The lightness measurement method according to the SCI method is defined in JIS Z8722 (2009). In the SCI system, since measurement is performed without removing specular reflection light, the color of an actual object is measured.

CIELAB color is a uniform color space specified in JIS Z8781 (2013), recommended in 1976, for measuring a color difference caused by a difference between a perception and a device-based measurement value. L for 3 coordinates of CI ELAB^*Value a^*Value b^*The values are represented. L is^*The value represents lightness and is represented by 0 to 100. L is^*A value of 0 indicates black, L^*A value of 100 indicates a diffuse reflection color of white.

[ Corrosion resistance evaluation test ]

The corrosion resistance (long-term corrosion resistance) of each test number of the galvanized steel sheet was evaluated by the following method. Test pieces of 75mm × 100mm were collected from each of the galvanized steel sheets of the test numbers. The cut surface and the back surface of the test piece were sealed with an adhesive tape for protection. Then, a salt spray test of 5% NaCl maintained at 35 ℃ was carried out in accordance with JIS Z2371 (2015). The test was conducted for 240 hours, and the rust percentage after the test was determined. If the rust rate is 0%, the corrosion resistance evaluation is judged as a, and if the rust rate is more than 0% and not more than 5%, the corrosion resistance evaluation is judged as B, and the corrosion resistance is evaluated as good. If the rust percentage is more than 5%, the evaluation of corrosion resistance is judged as C. However, the main problem of the present invention is to improve the texture visibility. Therefore, even if the corrosion resistance is evaluated as C, the example of the test number that passes the grain visual check test is judged as the present invention example.

[ test of adhesion ]

The adhesion of the colored resin layer of each test number galvanized steel sheet was evaluated by the following method. Test pieces 50mm in width by 50mm in length were prepared from the galvanized steel sheets of the respective test numbers. The obtained test piece was bent at 180 °. After the bending process, a tape peeling test was performed on the outer side of the bent portion. The appearance of the tape-peeled portion was observed with a magnifying glass having an enlargement ratio of 10 times. Then, evaluation was performed according to the following evaluation criteria. The bending was performed in an atmosphere of 20 ℃ with a spacer of 0.6mm sandwiched therebetween. The obtained results are shown in table 1 below.

(evaluation criteria)

A: no peeling of the coating film was observed

B: very little peeling of the coating film (peeling area. ltoreq.2%) was observed

C: peeling of a part of the coating film was observed (2% < peeling area ≦ 20%)

D: peeling of the coating film was observed (peeling area > 20%)

When the evaluation results are A to C, the adhesiveness is judged to be excellent. If D, the adhesion is judged to be low. However, the main problem of the present invention is to improve the texture visibility. Therefore, even if the adhesion is determined as D, the example of the test number that passes the grain visual check test is determined as the present invention example.

[ evaluation test of metallic feeling ]

The metallic feeling of each of the galvanized steel sheets of the test numbers was measured by the following method. At any point of the plated steel sheet 1 of each test No., the glossiness G60(Gl) in the direction parallel to the texture (hair line) and the glossiness G60(Gc) in the direction straight to the texture (hair line) were measured by a glossmeter. The gloss meter used was a gloss meter (trade name: UGV-6P) manufactured by Suga test machine Co. Based on the obtained glossiness Gl and glossiness Gc, Gc/Gl is obtained. If the texture could be visually confirmed and Gc/Gl ≦ 0.70, it was judged that an excellent metallic feeling was obtained (evaluation "A" in Table 1). If the texture could be visually confirmed and 0.70< Gc/Gl ≦ 0.90, it was judged that a good metallic feeling was obtained (evaluation "B" in Table 1). If the texture could not be visually confirmed, or if the texture could be visually confirmed but 0.90< Gc/Gl, it was judged that no metallic feeling was obtained (evaluation "C" in table 1). However, the main problem of the present invention is to improve the texture visibility. Therefore, even if the metallic feeling is determined as C, the example of the test number that passes the grain visual check test is determined as the present invention example.

[ evaluation results ]

Referring to Table 1, in test Nos. 4, 5, 8 to 17, 20 to 22, 25 to 27, and 30 to 32, the three-dimensional average roughness Sas of the bottom of the concave portion was more than 200nm and 2000nm or less. In these test numbers, F1 was 15.0 or less, and F2 was more than 1.0. Therefore, even if the lightness was 50 or less, the texture could be visually confirmed in the texture visual confirmation test (evaluation a or B) for these test numbers. In addition, these test numbers also showed excellent adhesion. Test No. 2 is outside the range of embodiment 1, and the corrosion resistance is slightly lower than that of the other invention examples, but it is within the range of embodiment 2, and has a high metallic feeling and good appearance.

In test nos. 4, 5, 8 to 17, 20 to 22, 25 to 27, and 30 to 32, the three-dimensional average roughness Sah of the top of the convex portion was more than 5nm and 200nm or less in test nos. other than test No. 5. Therefore, the test numbers 4, 10 to 17, 20 to 22, 25 to 27, and 30 to 32 had lower lightness than the test number 5, but the texture could be visually confirmed.

In test nos. 4, 5, 8 to 17, 20 to 22, 25 to 27, and 30 to 32, the base steel sheet exposure of test nos. other than test nos. 4 and 10 was less than 5%. Therefore, test Nos. 5, 8, 9, 11 to 17, 20 to 22, 35 to 27, and 30 to 32 showed a corrosion rate of less than 5% in the corrosion resistance evaluation test, and sufficient corrosion resistance was obtained (evaluation A or B).

On the other hand, in test No. 1, no plating texture was formed. Therefore, the maximum thickness DKmax, the minimum thickness DKmin, and the colorant content CK of the colored resin layer do not satisfy formula (2). In addition, the surface roughness ra (cl) and the surface roughness ra (cc) do not satisfy the formula (3). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test nos. 3 and 6, the minimum thickness DKmin of the colored resin layer and the colorant content CK in the colored resin layer do not satisfy formula (1). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No.7, the maximum thickness DKmax, the minimum thickness DKmin, and the colorant content CK of the colored resin layer do not satisfy formula (2). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 18, no plating texture was formed. Therefore, the maximum thickness DK max, the minimum thickness DKmin, and the colorant content CK of the colored resin layer do not satisfy formula (2). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 19, the minimum thickness DKmin of the colored resin layer and the colorant content CK in the colored resin layer do not satisfy formula (1). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 23, no plating texture was formed. Therefore, the maximum thickness DK max, the minimum thickness DKmin, and the colorant content CK of the colored resin layer do not satisfy formula (2). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 24, the minimum thickness DKmin of the colored resin layer and the colorant content CK in the colored resin layer do not satisfy formula (1). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 28, no plating texture was formed. Therefore, the maximum thickness DK max, the minimum thickness DKmin, and the colorant content CK of the colored resin layer do not satisfy formula (2). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 29, the minimum thickness DKmin of the colored resin layer and the colorant content CK in the colored resin layer do not satisfy formula (1). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

Embodiment 1 of the present invention has been described above. However, the above-described embodiments are only examples for implementing the present invention. Therefore, the present invention is not limited to the above-described embodiments, and can be implemented by appropriately changing the above-described embodiments without departing from the gist thereof.

(example 2)

Next, various examples manufactured to confirm the feasibility and effects of the plated steel sheet 1' according to embodiment 2 of the present invention will be described.

Galvanized steel sheets of test numbers shown in table 2 were prepared. The steel material (steel sheet) of each galvanized steel sheet was SPCC defined in JIS G3141 (2017), and the thickness was 0.6 mm.

Each steel material was subjected to a plating pretreatment. Specifically, Na was used at a concentration of 30g/L for each steel material₄SiO₄The treating liquid has a temperature of 60 deg.C and a current density of 20A/dm²Electrolytic degreasing was performed for 10 seconds, and water washing was performed. Immersing the electrolytically degreased steel in H with the concentration of 50g/L at 60 DEG C₂SO₄The aqueous solution was left for 10 seconds and washed with water.

The steel materials of the test numbers after the plating pretreatment were subjected to the following plating treatment to form zinc plating layers. Specifically, in test nos. 1 'to 16', zinc plating layers were formed by plating. Specifically, a plating bath containing 1.0mol/L of zinc sulfate heptahydrate and 50g/L of anhydrous sodium sulfate and having a pH adjusted to 2.0 was prepared. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc plating layer (indicated by "EG" in the column of "plating type" in table 2) was formed.

In test nos. 17 'to 20', a zinc plating layer containing Ni was formed as a zinc plating layer. Specifically, a plating bath adjusted to pH 2.0 containing zinc sulfate heptahydrate and nickel sulfate hexahydrate in a total amount of 1.2mol/L and further containing anhydrous sodium sulfate 50g/L was prepared. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc electrode containing 12 mass% of Ni and the balance of Zn and impurities was formedThe plating layer (represented by "Zn-12% Ni" in the column of "plating type" in Table 2).

In test nos. 21 'to 24', a zinc plating layer containing Fe was formed as a zinc plating layer. Specifically, a plating bath adjusted to pH 2.0 containing zinc sulfate heptahydrate and iron sulfate (II) heptahydrate in a total amount of 1.2mol/L and further containing anhydrous sodium sulfate at 50g/L was prepared. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc plating layer (represented by "Zn — 14% Fe" in the column of "plating type" in table 2) containing 14% by mass of Fe and the remainder consisting of Zn and impurities was formed.

In test nos. 25 'to 28', a zinc plating layer containing Co was formed as a zinc plating layer. Specifically, a plating bath adjusted to pH 2.0 containing zinc sulfate heptahydrate and cobalt sulfate hexahydrate in a total amount of 1.2mol/L and further containing anhydrous sodium sulfate 50g/L was prepared. In the electroplating, the bath temperature was 50 ℃ and the current density was 50A/dm². The plating time was adjusted so that the amount of adhesion was 30.0g/m²Left and right. Through the above steps, a zinc plating layer (represented by "Zn — 2% Co" in the column of "plating type" in table 2) containing 2% by mass of Co and the remainder consisting of Zn and impurities was formed.

After the formation of the galvanized layer, in test numbers 2 'to 16', 18 'to 20', 22 'to 24', and 26 'to 28', the galvanized steel sheet was subjected to texturing along the rolling direction RD of the steel sheet to impart the surface of the galvanized layer with a grain. Specifically, the polishing papers having various particle sizes were pressed against the surface of the zinc plating layer, and the pressing force and the number of times of polishing were changed to impart various hairlines. In the "texture" column of table 2, the presence or absence of texture processing and the type of texture processing in each test number are shown.

Colored resin layers were formed on the galvanized steel sheets on which the hair line was formed (test nos. 2 'to 16', 18 'to 20', 22 'to 24', and 26 'to 28') and the galvanized steel sheets on which the hair line was not formed (test nos. 1 ', 17', 21 ', and 25'). In the colored resin layer, as an organic resin, a paint having various concentrations and viscosities was prepared in which a urethane resin (HUX-232, manufactured by ADEKA corporation) was dispersed in water. Various concentrations of colorant (carbon black) were added to the coating. The carbon black was used under the trade name #850 manufactured by Mitsubishi chemical corporation.

The coating material was applied to the surface of the zinc coating layer of each test-number galvanized steel sheet by dipping it with a roller. And baking and drying the coated coating. Specifically, the galvanized steel sheet coated with the paint was charged into a furnace maintained at 250 ℃. The galvanized steel sheet is kept in the furnace for 1 to 5 minutes until the arrival temperature of the galvanized steel sheet reaches 210 ℃. After the holding, the galvanized steel sheet was taken out of the furnace and cooled.

The viscosity of the coating material was adjusted by using a viscosity adjuster (product name: BYK-425, manufactured by BYK). Specifically, the viscosity of the coating material is adjusted so that the coating material viscosity is 10(Pa · s) or more at a shear rate of 0.1(1/sec) and 0.01(Pa · s) or less at a shear rate of 1000 (1/sec). Through the above steps, a colored resin layer was formed on the galvanized layer of each test number.

By the above-described manufacturing method, galvanized steel sheets of the respective test numbers were manufactured. In test No. 16', a urethane resin (HUX-232, manufactured by ADEKA) having no colorant was applied between the colored resin layer and the zinc-plated layer by 0.5. mu.m. Then, a colored resin layer was formed.

[ evaluation test ]

[ three-dimensional average roughness Saave' determination test ]

The maximum three-dimensional average roughness of the texture (hairline) of the surface of the zinc coating layer of each test number galvanized steel sheet was measured by the following method. First, the colored resin layer of the galvanized steel sheet was removed by using a solvent (trade name: Neolever S-701, manufactured by Sanko chemical Co., Ltd.) which did not attack the galvanized layer. In the surface of the zinc plating layer, a range having a length of 1000 μm in a direction perpendicular to the extending direction of the texture (hairline) is arbitrarily selected. The roughness profile of the texture was measured over a selected length of 1000 μm. The roughness profile was measured using a three-dimensional surface roughness measuring machine (SURFCOM 1500DX3, precision, tokyo). Of the positions on the measured roughness profile, 10 low-height positions are designated in order from the low-height position, and the low-height positions are defined as recess bottom points PRE1 ', PRE2 ', …, and PRE10 ' in order from the low-height position. Of the positions on the roughness profile obtained by the measurement, 10 height positions were designated in order from the height, and the height positions were defined as projection apexes PCO1 ', PCO2 ', …, and PCO10 '.

As shown in FIG. 14A, in a plan view of the surface of the galvanized layer, a minute recessed region of 1 μm × 1 μm centered on each of the defined recessed bottom points PREk' (k is 1 to 10) is specified. Similarly, as shown in FIG. 14B, in a plan view of the surface of the galvanized layer, a minute convex region of 1 μm × 1 μm centered on each of the defined convex peaks PCOk' (k is 1 to 10) is specified.

The three-dimensional average roughness Sa' was measured in the 10 minute recessed regions and the 10 minute projected regions specified by the above method. The designation of the fine recessed regions and the fine raised regions and the measurement of the three-dimensional average roughness Sa' were carried out using a laser microscope (trade name: VK-9710) manufactured by Keyence. In VK-9710, the display resolution in the height direction is 1nm or more, and the display resolution in the width direction is 1nm or more. The arithmetic average of the measured three-dimensional average roughness Sa 'of 20 (10 fine recessed regions and 10 fine raised regions) was defined as a three-dimensional average roughness Saave'.

[ DKMin ', DKmax' determination test ]

The thickness (DKmin ', DKmax') of the colored resin layer of each test number galvanized steel sheet was measured by the following method. From each of the galvanized steel sheets of test numbers, a sample having a cross section perpendicular to the extending direction of the grain (hairline) on the surface was collected. An observation cross section in a range having a length of 100 μm in a direction perpendicular to the extending direction of the grain (hair line) in the sample was observed with a reflection electron image (BSE) of 2000 times using a Scanning Electron Microscope (SEM). In the observation cross section, the thickness of the colored resin layer was measured at a pitch of 0.5 μm in the direction WD'. Among the measured thicknesses, the smallest thickness was defined as the smallest thickness DKmin' (μm). Of the thicknesses obtained by the measurement, the maximum thickness was defined as the maximum thickness DK max' (μm).

[ measurement test for CK' content of colorant ]

The content (area%) of the coloring agent in the colored resin layer of each test number galvanized steel sheet was determined by the following method. A sample having a cross section perpendicular to the extending direction of the texture (hairline) on the surface was collected. In the sample, a cross section perpendicular to the extending direction of the texture (hairline) was taken as a viewing surface. A film sample capable of observing the colored resin layer and the zinc plating layer on the observation surface was prepared from the sample using FIB. The film thickness of the thin film sample was 150 nm. In the observation surface of the prepared film sample, observation was performed using TEM with a length of 3 μm in the direction perpendicular to the thickness direction of the colored resin layer (i.e., direction WD ') and a field of view having a length including the entire colored resin layer in the thickness direction of the colored resin layer (i.e., direction TD'). In TEM observation, the resin and the colorant in the colored resin layer can be identified by contrast. The total area A1' (μm) of the colorants in the colored resin layer in the observation cross section was determined²). Then, the area A0' (μm) of the colored resin layer in the observation cross section was determined²). Based on the total area a1 'and the area a 0' obtained, the content of the colorant (area%) in the colored resin layer 11 was obtained by the following equation.

CK’＝A1’/A0’×100

[ measurement tests of the roughness Ra (CC) and Ra (CL) of the colored resin layer ]

The roughness ra (cc) 'and ra (cl)' in the colored resin layer of each test-number galvanized steel sheet were determined by the following methods.

The surface roughness ra (cl)' was measured by the method for measuring arithmetic average roughness specified in JIS B0601 (2013). Any 10 positions on the surface of the colored resin layer were used as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured at an evaluation length extending in the extending direction of the texture (hair line). The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using a three-dimensional surface roughness measuring instrument (SURFCOM 1500D X3, precision product of tokyo) at a measuring speed of 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cl)'.

Similarly, the surface roughness ra (cc)' was measured by the method for measuring arithmetic average roughness specified in JIS B0601 (2013). Any 10 positions on the surface of the colored resin layer were used as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured at an evaluation length extending in a direction perpendicular to the extending direction of the texture (hair line). The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using the three-dimensional surface roughness measuring instrument described above, and the measurement speed was set to 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (cc)'.

[ surface roughness Ra of Zinc plating layer (MC)' measurement test ]

The surface roughness ra (mc)' of the galvanized layer of each test number galvanized steel sheet was determined by the following method.

The surface roughness ra (mc)' was measured by the method for measuring arithmetic average roughness specified in JIS B0601 (2013). The colored resin layer of the galvanized steel sheet was removed by using a solvent (trade name: Neolever S-701, manufactured by Sanko Co., Ltd.) which did not attack the galvanized layer. In the texture (hairline) of the galvanized layer after the colored resin layer was removed, arbitrary 10 positions were set as measurement positions. At each measurement position, the arithmetic average roughness Ra was measured at an evaluation length extending in a direction perpendicular to the extending direction of the texture (hair line). The evaluation length was set to 5 times the reference length (cut-off wavelength). The arithmetic mean roughness Ra was measured using the three-dimensional surface roughness measuring instrument described above, and the measurement speed was set to 0.5 mm/sec. From the 10 arithmetic average roughness values Ra thus obtained, the maximum arithmetic average roughness Ra, the 2 nd maximum arithmetic average roughness Ra, the minimum arithmetic average roughness Ra, and the 2 nd minimum arithmetic average roughness Ra were removed, and the arithmetic average of the remaining 6 arithmetic average roughness Ra was defined as the surface roughness Ra (mc)' (μm).

[ base Steel sheet Exposure Rate measurement test ]

[ texture visual confirmation test ]

[ lightness measurement test ]

The CIE standard light source D65 is defined in JIS Z8720 (2000 ") color measuring illuminant (standard light) and standard light source", and is also defined in ISO 10526 (2007). CIE is an abbreviation for Co mmision International de l' Eclairage and represents the International Commission on illumination. The CIE standard illuminant D65 is used to represent the color of an object under daylight illumination. Regarding the viewing angle of 10 °, the same is specified in JIS Z8723 (2009) "visual comparison method of surface color", and ISO/DIS 3668.

[ Corrosion resistance evaluation test ]

The corrosion resistance (long-term corrosion resistance) of each test number of the galvanized steel sheet was evaluated by the following method. Test pieces of 75mm × 100mm were collected from each of the galvanized steel sheets of the test numbers. The cut surface and the back surface of the test piece were sealed with an adhesive tape for protection. Then, a salt spray test of 5% NaCl maintained at 35 ℃ was carried out in accordance with JIS Z2371 (2015). The test was conducted for 240 hours, and the rust percentage after the test was determined. If the rust rate is 0%, the corrosion resistance evaluation is judged as a, and if the rust rate is more than 0% and not more than 5%, the corrosion resistance evaluation is judged as B, and the corrosion resistance is evaluated as good. If the rust percentage is more than 5%, the evaluation of corrosion resistance is judged as C. However, the main problem of the present invention is to improve the appearance such as the visibility of the texture. Therefore, even if the corrosion resistance is evaluated as C, the example of the test number that passes the grain visual check test is judged as the present invention example.

[ evaluation test of metallic feeling ]

[ evaluation results ]

Referring to table 1, in test nos. 3 ', 6 ' to 16 ', 19 ', 20 ', 23 ', 24 ', 27 ' and 28 ', the three-dimensional average roughness Saave ' was more than 5nm and 200nm or less, and the minimum thickness DKmi ' of the colored resin layer and the content CK ' of the colorant in the colored resin layer satisfied formula (1 '). Further, the maximum thickness DKmax ', the minimum thickness DKmin', and the colorant content CK 'of the colored resin layer satisfy formula (2'). Therefore, in the texture visual confirmation test, the texture can be visually confirmed (evaluation a or B).

In test nos. 3 ', 6' to 16 ', 19', 20 ', 23', 24 ', 27' and 28 ', the base steel sheet exposure rate was less than 5% in test nos. other than test No. 3'. Therefore, in the corrosion resistance evaluation test, the rust percentage was less than 5%, and sufficient corrosion resistance was obtained (evaluation a).

On the other hand, in test No. 1 ', the three-dimensional average roughness Saave' was too large. Further, the maximum thickness DKmax ', the minimum thickness DKmin', and the colorant content CK 'of the colored resin layer do not satisfy formula (2'). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 2 ', the minimum thickness DKmin' of the colored resin layer and the content CK 'of the colorant in the colored resin layer do not satisfy formula (1'). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 4 ', the minimum thickness DKmin' of the colored resin layer and the content CK 'of the colorant in the colored resin layer do not satisfy formula (1'). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 5 ', the maximum thickness DKmax ', the minimum thickness DKmin ', and the colorant content CK ' of the colored resin layer do not satisfy formula (2 '). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 17 ', the maximum thickness DKmax ', the minimum thickness DKmin ', and the colorant content CK ' of the colored resin layer do not satisfy formula (2 '). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 18 ', the minimum thickness DKmin' of the colored resin layer and the content CK 'of the colorant in the colored resin layer do not satisfy formula (1'). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 21 ', the maximum thickness DKmax ', the minimum thickness DKmin ', and the colorant content CK ' of the colored resin layer do not satisfy formula (2 '). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 22 ', the minimum thickness DKmin' of the colored resin layer and the content CK 'of the colorant in the colored resin layer do not satisfy formula (1'). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 25 ', the maximum thickness DKmax ', the minimum thickness DKmin ', and the colorant content CK ' of the colored resin layer do not satisfy formula (2 '). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

In test No. 26 ', the minimum thickness DKmin' of the colored resin layer and the content CK 'of the colorant in the colored resin layer do not satisfy formula (1'). Therefore, in the texture visual confirmation test, the texture could not be visually confirmed (evaluation C).

(example 3)

In test numbers 12, 14 to 16, 20 to 21, 25 to 26, 30 to 31, 13 'to 16', 19 'to 20', 23 'to 24', and 27 'to 28' of examples 1 and 2, the same paint was used and the coating was performed in several times so that the total film thickness of the colored resin layers was the same, thereby obtaining a laminated resin layer. The test numbers coated with the laminated resin are shown in tables 3A and 3B as the original test numbers plus a #. In the laminated resin layer forming step, a manufacturing line including a resin layer manufacturing apparatus in which a colored resin coating apparatus and a baking oven are combined is used. In the case of laminating resins, a resin layer manufacturing process using a resin layer manufacturing apparatus is performed a plurality of times. In test nos. 15# and 15' # where a transparent resin layer containing no coloring pigment was laminated as the third layer, the number of laminated resin layers was 3 (the "number of laminated layers" in the "laminated resin layer" column was described as "3"). In test nos. 16# and 16' # where a transparent resin layer containing no coloring pigment was laminated as the first layer, the number of laminated resin layers was 3 (the "number of laminated layers" in the "laminated resin layer" column was described as "3"). In the other laminated resin formation test numbers, the number of colored resin layers in the laminated resin layer was set to 2 (described as "2" in the column of "laminated layer number" in the column of "laminated resin layer").

[ evaluation test ]

[ measurement of the content CK and thickness DK of the pigment in each colored resin layer LK ]

The pigment content CK and the thickness DK of each colored resin layer of the laminated resin layer of each test number were measured by the following methods. Referring to fig. 15A, the design galvanized steel sheet is cut in the normal direction ND to prepare a cut section CS including the normal direction ND and the sheet width direction TD. Referring to fig. 15B, in the cut section CS, a direction perpendicular to the normal direction ND (the plate width direction TD in the present embodiment) is defined as a cut section width direction CD. The cut section CS is divided into 3 equal parts in the cut section width direction CD. In each of the 3-divided blocks X1 to X3, a sample SA including the laminated resin layer 30 was collected at the center in the cross-sectional width direction CD. Each of the 3 samples SA includes at least the laminated resin layer 30 and the galvanized layer 10. The length in the cross-sectional width direction CD is 10mm, and the length in the direction perpendicular to the normal direction ND and the cross-sectional width direction CD is 10 mm. For the cut-out sample SA, a sample capable of observing the laminated resin layer 30 and the galvanized layer 10 with a transmission electron microscope was prepared using a focused ion beam apparatus (FIB).

A surface (observation surface) including the normal direction ND and the cross-sectional width direction CD of the sample SA was observed with a Scanning Electron Microscope (SEM) at a reflection electron image (BSE) of 2000 ×. In observation of a reflected electron image (BSE) using a Scanning Electron Microscope (SEM), the base steel sheet, the galvanized layer, and the laminated resin layer can be easily distinguished by contrast. In addition, in the laminated resin layer, since resin layers having different compositions are used for the respective colored resin layers, they can be identified by their contrast.

After identifying each colored resin layer, the content CK (volume%) of the pigment in each colored resin layer and the average thickness DK of each colored resin layer were determined by the following method.

In the transmission electron microscope observation, the total area A1(μm) of the plurality of pigments in the colored resin layer on the observation surface was determined²). Then, the area A0(μm) of the colored resin layer on the observation surface was determined²). Based on the total area a1 and the area a0 thus obtained, the area ratio (% by area) of the pigment in the colored resin layer was obtained by the following formula.

Area ratio of A1/A0X 100

The area ratios of the above pigments were determined for 3 samples, and the average of the determined 3 area ratios was defined as the pigment content CK (vol%) of the colored resin layer.

In addition, in each sample SA, the thickness (μm) was measured at an arbitrary 1 point of each colored resin layer. The average of the 3 thicknesses obtained in the 3 samples SA was defined as the thickness DK (μm) of the colored resin layer. The pigment content CK (area%), the thickness DK (μm) of each of the colored resin layers thus identified was determined by the above method.

The color density index IK, which is an index of the color density of each colored resin layer, is obtained from the pigment content CK and the thickness DK of each colored resin layer by the following formula.

Color density index IK ═ CK × DK

Then, the total value of the color density indexes of the respective colored resin layers is obtained. The obtained total value is shown in the column of "total color density index" in the column of "laminated resin layer" in tables 3A and 3B.

[ measurement of thickness of laminated resin layer ]

The thickness of the laminated resin layer 30 is measured by the following method. Referring to fig. 15A and 15B, in the cross section CS, a direction perpendicular to the normal direction ND is defined as a cross-sectional width direction CD (corresponding to the plate width direction TD in the present embodiment). The cut section CS is divided into 3 equal parts in the cut section width direction CD. In blocks X1 to X3 of 3 equal divisions, samples SA including the laminated resin layer 30 were collected at the center position in the cross-sectional width direction CD. Each of the 3 samples SA includes at least the laminated resin layer 30 and the galvanized layer 10. The length in the cross-sectional width direction CD was 10 mm. In the sample SA, the length in the direction perpendicular to the normal direction ND and the cross-sectional width direction CD is set to 10 mm. The cut section CS of the cut sample SA was subjected to gold vapor deposition. Then, the sample SA was sandwiched between the embedding resins by a clamping plate, and ground to make the cut section CS an observation surface, thereby preparing an observation sample. The observation surface of the observation sample was observed with a Scanning Electron Microscope (SEM) at a reflection electron image (BSE) of 2000 × magnification. In observation of a reflected electron image (BSE) using a Scanning Electron Microscope (SEM), the base steel sheet 100, the galvanized layer 10, and the laminated resin layer 30 can be easily distinguished by contrast. In each sample SA, the thickness of the laminated resin layer 30 was measured at 10 points at a pitch of 100 μm in the cross-sectional width direction CD. The average value of the thicknesses (total of 30 points) measured in the 3 samples SA was defined as the thickness (μm) of the laminated resin layer 30. The thickness (μm) of the laminated resin layer obtained by the measurement is shown in the column "total thickness" of the laminated resin layer "in table 1.

[ most intensely colored resin layer L_1STAnd 2 nd dense colored resin layer L_2NDIs selected from]

In each colored resin layer, the color density index IK is maximizedThe colored resin layer of (2) is defined as "the most intense colored resin layer L_1ST", will follow the most intensely colored resin layer L_1STThen, the colored resin layer having the highest color density index IK, that is, the colored resin layer having the 2 nd highest color density index IK is defined as "the 2 nd dense colored resin layer L_2ND". The resin layer L is colored in the most intense color_1STThe pigment content (area%) of (C) is defined as_1ST", coloring the resin layer L of the most intense color_1STIs defined as "D" in terms of thickness (μm)_1ST". A 2 nd color-dense colored resin layer L_2NDThe pigment content (area%) of (C) is defined as_2ND", the 2 nd color-dense colored resin layer L_2NDIs defined as "D" in terms of thickness (μm)_2ND". Most intensely colored resin layer L_1STPigment content C of_1STThickness D_1ST(ii) a No. 2 dark colored resin layer L_2NDPigment content C of_2NDThickness (. mu.m) D_2NDAs shown in tables 3A and 3B. In tables 3A and 3B, "darkest colored resin layer L_1ST"lamination position" in the column indicates the most intense colored resin layer L_1STIs the second layer. For example, in test No. 12#, the most intensely colored resin layer L is shown_1ST Layer 1. Similarly, "2 nd dark colored resin layer L" in tables 3A and 3B_2ND"lamination position of column" means the 2 nd color-rich colored resin layer L_2NDIs the second layer. For example, in test No. 12#, the 2 nd dark colored resin layer L is shown_2NDIs layer 2.

And, the most intense colored resin layer L is used_1STPigment content C of_1STThickness D_1ST(ii) a No. 2 dark colored resin layer L_2NDPigment content C of_2NDThickness (. mu.m) D_2NDThe color density ratio RF is obtained by the following equation.

Color density ratio RF ═ C_1ST×D_1ST)/(C_2ND×D_2ND)

The color density ratio RF obtained is shown in the column of "color density ratio RF" in the column of "laminated resin layer" in tables 3A and 3B.

[ surface visual confirmation test of galvanized layer ]

Each sample was placed in an environment corresponding to sunlight on a sunny day (illuminance of about 65000 lux), and it was judged whether or not the surface energy of base steel sheet 100 was visually confirmed.

[ color unevenness evaluation test ]

The color unevenness of the design galvanized steel sheet of each test number was evaluated by the following method. Referring to fig. 16, 81 measurement points (P1 to P81) were designated at a pitch of 15mm in an arbitrary measurement line segment OD1 of 1200mm running straight in the extending direction HD of the hairline 23 of the design galvanized steel sheet 1 of each test number. L was determined at each of the measurement points P1 to P81^*a^*b^*L in a color system^*Value a^*A value, and b^*The value is obtained. Δ L in 2 adjacent measurement points Pi and Pi +1(i is a natural number of 1 to 80)^*Value, Δ a^*Value, Δ b^*The value was obtained by the following equation.

ΔL^*＝L^*i-L^*i+1

Δa^*＝a^*i-a^*i+1

Δb^*＝b^*i-b^*i+1

Based on the obtained Δ L^*、Δa^*、Δb^*The color difference Δ E between 2 adjacent measurement points was obtained by the following equation^*。

ΔE^*＝((ΔL^*)²+(Δa^*)²+(Δb^*)²)

Based on the obtained 80 Δ E^*The color unevenness was evaluated by the following criteria.

And G, grading: color difference Δ E between adjacent 2 points^*90% or more of the total amount of the components is 2.0 or less

And (3) scoring P: color difference Δ E between adjacent 2 points^*More than 11% of (A) is more than 2.0

The obtained results are shown in the column "color unevenness" in the column "evaluation test" in table 3A and table 3B.

[ color fluctuation evaluation test ]

The color fluctuation of the design galvanized steel sheet of each test number was evaluated by the following method. Referring to fig. 17, 20 measurement positions S1 to S20 were designated at a pitch of 50000mm (50m pitch) in the rolling direction RD in the design galvanized steel sheet 1 of each test number. Then, at each of the measurement positions S1 to S20, the color difference Δ E between the measurement points Q1 and Q2 was determined at a distance of 1000mm from the direction in which the hairline extends HD and is running straight (straight direction OD)^*。

Based on the obtained 20 color differences Delta E^*The color fluctuation was evaluated by the following criteria.

And G, grading: 20 points all Δ E^*≤3.0

And (3) scoring P: more than 1 Δ E exists in 20 points^*>Point of 3.0

The obtained results are shown in the column "color variation" in the column "evaluation test" in table 1.

In the color unevenness evaluation test and the color fluctuation evaluation test, L at each of the measurement points P1 to P81, Q1 and Q2^*Value a^*Value and b^*The value was measured using a colorimeter (trade name: CM-2600d) manufactured by Konika Minneta. In the measurement, CIE standard illuminant D65 was used as a illuminant, the viewing angle was set to 10 °, and L was obtained by expressing color by CIELAB using SCE method^*Value a^*A value, and b^*The value is obtained.

The CIE standard light source D65 is defined in JIS Z8720 (2000 ") color measuring illuminant (standard light) and standard light source", and is also defined in ISO 10526 (2007). CIE is an abbreviation of Co mmision International de l' Eclairage and represents the International Commission on illumination. The CIE standard illuminant D65 is used to represent the color of an object under daylight illumination. Regarding the viewing angle of 10 °, the same is specified in JIS Z8723 (2009) "visual comparison method of surface color", and ISO/DIS 3668.

The SCE method is also called a specular reflection light removal method, and indicates a method of removing specular reflection light and measuring a color. The definition of the SCE pattern is defined in JIS Z8722 (2009). In the SCE method, since measurement is performed by removing specular reflection light, a color (so-called "perceived color") close to a color actually seen by human eyes is measured.

CIELAB indicates a uniform color space specified in JIS Z8781 (2013) recommended in 1976 for measuring a color difference due to difference in appearance and device. L for 3 coordinates of CIELAB^*Value a^*Value b^*The values are represented. L is^*The value represents lightness and is represented by 0 to 100. L is^*A value of 0 indicates black, L^*A value of 100 indicates a diffuse reflection color of white. a is^*The values represent colors between red and green. a is^*The value indicates a greenish color if it is a negative number, and indicates a reddish color if it is a positive number. b^*The values represent colors between yellow and blue. b^*If the number is negative, it indicates a bluish color, and if the number is positive, it indicates a yellowish color.

[ evaluation results ]

Referring to tables 3A and 3B, one or both of the "color unevenness" and the "color variation" of the test numbers (numbers without # added) that were not laminated and resinated were evaluated as "P", whereas the test numbers (numbers with # added) that were laminated and resinated were evaluated as "G" in both of the "color unevenness" and the "color variation".

Description of the symbols

1, 1' plated steel sheet

10, 10' zinc coating

10S, 10S' texture

11, 11' colored resin layer

30 laminated resin layer

31, 31' resin

32, 32' colorant

100, 100' base steel plate.

Claims

1. A plated steel sheet comprising:

a base steel plate having a base texture on the surface,

the zinc plating layer has a plating texture on the surface thereof,

the colored resin layer contains a coloring agent,

when the rolling direction of the base steel sheet is defined as a1 st direction and a direction perpendicular to the 1 st direction on the surface of the plated steel sheet is defined as a 2 nd direction, the plated steel sheet satisfies the following (a) to (C):

F1＝DKmin×CK (1)

(C) in the range of 100 μm in the 2 nd direction, the maximum thickness (μm) of the colored resin layer is defined as DKmax, and when F2 is defined by formula (2), the F2 is greater than 1.0,

F2＝(DKmax-DKmin)×CK (2)。

2. the plated steel sheet according to claim 1, which further satisfies the following (D):

3. The plated steel sheet according to claim 2, wherein,

a plurality of the convex portions and a plurality of the concave portions extend in the 1 st direction,

the plurality of convex portions and the plurality of concave portions are aligned in the 2 nd direction.

4. The plated steel sheet according to claim 3, wherein,

the texture of the parent material is hair line,

the plated texture is a hair line,

the plated steel sheet further satisfies the following (E) and (F):

F3＝Ra(CC)/Ra(CL) (3)

5. The plated steel sheet according to any one of claims 1 to 4,

lightness L when the plated steel sheet is observed from the side of the colored resin layer^*(SCI) is 45 or less.

6. The plated steel sheet according to any one of claims 1 to 5,

f1 is 13.5 or less.

7. The plated steel sheet according to any one of claims 1 to 6, wherein,

f2 is greater than 2.0.

8. The plated steel sheet according to any one of claims 4 to 7,

the F3 is 1.15 or more.

9. The plated steel sheet according to any one of claims 1 to 8, wherein,

the exposure rate of the base steel plate of the zinc coating is less than 5 percent.

10. The plated steel sheet according to claim 2, wherein,

a plurality of the convex portions are formed by grinding the surface of the zinc plating layer,

a plurality of the recesses are not ground.

11. A plated steel sheet comprising:

a base steel plate,

A zinc-plated layer formed on the surface of the base steel sheet, and

a colored resin layer formed on the zinc-plated layer,

the colored resin layer contains a coloring agent,

the plated steel sheet satisfies the following requirements (A ') to (C'):

DKmin’×CK’≤15.0(1’)；

(DKmax’-DKmin’)×CK’>1.0(2’)。

12. the plated steel sheet according to claim 11,

the texture is a hair line,

the plated steel sheet satisfies the following (D ') and (E'):

Ra(CC)’≥Ra(CL)’×1.10(3’)；

13. The plated steel sheet according to claim 11 or claim 12, wherein,

14. The plated steel sheet according to any one of claims 1 to 13, wherein,

the colored resin layer is a laminated resin layer,

the laminated resin layer includes a plurality of colored resin layers laminated in a direction normal to the surface of the base steel sheet,

in the plurality of colored resin layers, the sum of the product of the content (area%) of the colorant in the colored resin layer and the thickness (μm) of the colored resin layer is 15.0 area%. μm or less,

among the plurality of colored resin layers, when a colored resin layer having a largest product of a content (area%) of the colorant in the colored resin layer and a thickness (μm) of the colored resin layer is defined as a most dense colored resin layer, and a colored resin layer having a largest product 2 of the content of the colorant in the colored resin layer and the thickness of the colored resin layer is defined as a 2 nd dense colored resin layer, a content C of the colorant in the most dense colored resin layer_1ST(area%), thickness D of the densest colored resin layer_1ST(μm), content C of the colorant of the 2 nd color-dense colored resin layer_2ND(area%) and thickness D of the 2 nd color-colored resin layer_2ND(mum) satisfies the formula (4),

1.00<(C_1ST×D_1ST)/(C_2ND×D_2ND)≤4.00 (4)。

15. the plated steel sheet according to claim 14, wherein,

the thickness of the laminated resin layer is 10.0 [ mu ] m or less.

16. The plated steel sheet according to claim 14 or claim 15, wherein,

the laminated resin layer further comprises 1 or more transparent resin layers containing no colorant,

the laminated resin layer is formed by laminating the plurality of colored resin layers and the 1 or more transparent resin layers.