KR20200105697A - Zinc-based electroplated steel sheet - Google Patents

Abstract

This zinc-based electroplated steel sheet includes a steel sheet and a zinc-based electroplating layer located on at least one surface of the steel sheet and having a hairline stretched on the surface in a predetermined direction. The zinc-based electroplating layer has a microscopic roughness having a three-dimensional average surface roughness Sa (1 μm)h of more than 200 nm and 2000 nm or less, and a microscopic smoothing portion having a three-dimensional average surface roughness Sa (1 μm) s of more than 5 nm and 200 nm or less. . In the zinc-based electroplating layer, a three-dimensional average surface roughness Sa (50 μm) is continuously measured along a predetermined direction, and R50, which is the ratio of the Sa (50 μm) in the adjacent area formed by two adjacent areas. Is calculated, and when the adjacent area having R50 of less than 0.667 or 1.500 or more is referred to as the adjacent area A, the ratio of the number of adjacent areas A is 30% or more.

Description

Zinc-based electroplated steel sheet

The present invention relates to a zinc-based electroplated steel sheet.

This application claims priority based on patent application 2018-071944 for which it applied to Japan on April 3, 2018, and uses the content here.

Items that stand out to people, including electric equipment, building materials, and automobiles, generally require design. As a method of improving the design properties, a method of applying a coating or attaching a film to the surface of an article is common, but in recent years, applications of materials utilizing the texture of metal are increasing mainly in Europe and the United States, which aims for nature. From the viewpoint of making use of the texture of the metal, coating or resin coating damages the texture of the metal. Therefore, stainless steel or aluminum having excellent corrosion resistance even without coating is used as a material for an article. In addition, in order to improve the design properties of stainless steel or aluminum materials, arc-shaped fine irregularities, called vibrations, or embossing are applied, but the appearance of fine linear irregularities called hairlines is particularly preferred. It is widely used.

Hairline finish (HL finish) is one of the surface finishes of stainless steel, and is defined in JIS G4305:2012 as “abrasive material of an appropriate particle size, and finished by polishing so as to generate continuous polishing stripes”.

However, since stainless steel materials and aluminum materials are expensive, inexpensive materials to replace these stainless steel materials and aluminum materials are desired. As one of such alternative materials, it has the same high design properties and suitable corrosion resistance as stainless steel and aluminum materials, and has a hairline appearance, suitable for use in electrical equipment or building materials, and the texture of metal (metallic luster, metallic There is a steel material having excellent persimmon (hereinafter referred to as "metallic feeling").

As a technique for imparting moderate corrosion resistance to steel materials, a technique of imparting zinc plating or zinc alloy plating excellent in sacrificial corrosion resistance to steel materials has been widely used. As a technology related to a steel material with hairline design, such as zinc plating or zinc alloy plating (hereinafter, zinc plating and zinc alloy plating are collectively referred to as ``zinc plating''), for example, a hairline A technology for forming an adhesive layer having a light-transmitting property and a film layer having a light-transmitting film layer plating layer on the surface of a plating layer having a surface roughness Ra (arithmetic mean roughness) of 0.1 to 1.0 µm in a right angle direction (refer to Patent Document 1 below); The hairline direction formed on the surface layer of the Zn-Al-Mg-based hot-dip plating layer and the roughness parameters (Ra and PPI) in the direction orthogonal to the hairline are in a specific range, and a transparent resin film layer on the surface of the Zn-Al-Mg-based hot-dip plated layer (Refer to Patent Document 2 below) or a technology of coating a resin whose surface roughness is within a certain range on a steel sheet whose texture is transferred by rolling to Zn and Zn alloy plating (hereinafter Patent Document 3). See also) is proposed.

Japanese Registered Utility Model No. 392959 Gazette Japanese Patent Publication No. 2006-124824 Japanese Patent Publication No. 2013-536901 International Publication No. 2015/125887

However, in the technique of coating an organic resin on a steel sheet with hairline design, proposed in Patent Documents 1 to 3, hairline design can be realized and a certain corrosion resistance can be expressed, but the resin There was a problem that the metallic feel was lost due to the coating.

Here, as a method of forming a hairline, a steel plate rolling method in which a plated steel sheet to form a hairline is rolled with a rolling roll having a predetermined roughness, and a plating grinding method that grinds the surface of a plated steel sheet to form a hairline. There is a law. The loss of metallic feel as described above was particularly remarkable for a plated steel sheet having a hairline formed by the steel sheet rolling method. The reason for the remarkable loss of metallic feel is not clear, but in a plated steel plate produced by a steel plate rolling method with a hairline, incident light is diffusely reflected across the entire surface of the plated layer due to the plated crystal particles present on the outermost surface of the plated layer. It seems to be because of it. Therefore, when it is assumed that the surface of the plated steel sheet on which the hairline is formed is subjected to resin coating described below, it is considered that the formation of the hairline by the steel sheet rolling method is not appropriate.

As a method for improving glossiness, a method of minimizing plated crystal grains by adding a predetermined organic substance additive to an electroplating solution is known (see, for example, Patent Document 4). However, when the crystal grains of the plating are made fine, there is a problem that the processing adhesion to the resin film is lowered when the upper layer of the plating is resin coated. In addition, in the method described in Patent Document 4, it is necessary to use an organic substance additive in order to obtain smooth plating, and thus there is a problem that the cost of drag-out (waste liquid) treatment of the plating solution increases.

In addition, since the stainless steel material has good corrosion resistance of the stainless steel material itself due to the oxide film present on the surface thereof, coating for improving the corrosion resistance is unnecessary. That is, since the metal base itself can be used on the surface, the problem of loss of metallic feel due to resin coating does not exist in the first place. On the other hand, when resin coating is performed on a stainless steel material, it is an object to impart coloration or other texture. Therefore, in the stainless steel material, the loss of metallic feeling as found by the present inventors did not become a problem. Such circumstances are the same for aluminum materials.

In addition, depending on the application, a matte or appearance with a metallic feel and suppressed gloss may be preferred as a calm texture. As described above, the hairline is usually formed by grinding and grinding the surface with a polishing or grinding belt, or rolling using a rolling roll, but a location where the roughness is lowered by polishing or grinding (hereinafter referred to as ``polishing, etc.''). Is inevitably high gloss, and it was difficult to realize a matte or appearance with low gloss.

In addition, in a zinc-based plated steel sheet, resin coating is often performed in order to maintain corrosion resistance and aesthetic appearance, but the adhesion between the zinc-based plating layer and the resin film sometimes decreases with the formation of the hairline.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to have a hairline appearance while suppressing an increase in gloss, and to maintain a metallic feel when a resin film is formed on the upper layer of plating, while maintaining high film adhesion. It is to provide a zinc-based electroplated steel sheet capable of realizing.

The present inventors intensively studied the method for improving the metallic feel, and thought that it would be possible to improve the metallic feel even in the case where the surface of the plating layer was resin-coated, as long as diffuse reflection on the outermost surface of the plating layer could be suppressed. The inventors of the present invention have conducted further studies under such an idea, and as a result, in order to suppress diffuse reflection, by providing a smooth portion having a surface roughness in a microscopic range of not more than a predetermined threshold value on the surface of the plating layer, it has come to the knowledge that diffuse reflection can be suppressed.

In addition, the present inventors have found that by appropriately adjusting the ratio of the roughness and the smoothing portion in which the surface roughness in the microscopic range on the surface of the plating layer exceeds a predetermined threshold, an excessive increase in gloss can be suppressed while making both metallic feel and film adhesion. I could get it. In addition, "surface roughness in a microscopic range" is mentioned later.

Under the above-described various knowledge, the present inventors conducted a thorough examination of the distribution state of the rough and smooth portions, and even when an organic resin coating layer was provided on the upper layer of the zinc-based electroplating layer, an excessive increase in gloss was achieved while achieving both metallic feel and film adhesion. The present invention was completed by conceiving conditions for suppression.

The gist of the present invention completed based on these findings is as follows.

(1) In a zinc-based electroplated steel sheet according to an aspect of the present invention, a zinc-based electroplating layer having a steel sheet and a hairline extending in a predetermined direction is provided on at least one surface of the steel sheet, and the The zinc-based electroplating layer has a microscopic roughness having a three-dimensional average surface roughness Sa (1 μm) h of more than 200 nm and 2000 nm or less defined in (A) below, and a three-dimensional average surface roughness Sa (1) defined in (B) below. Μm) s is more than 5 nm and not more than 200 nm.

In the zinc-based electroplating layer, a three-dimensional average surface roughness of a region of 50 μm×50 μm along each of a hairline direction in which the hairline is stretched and a hairline orthogonal direction orthogonal to the hairline direction By successively measuring Sa (50 μm), R50, which is the ratio of Sa (50 μm), is calculated in the adjacent area formed by the two adjacent areas, and the adjacent area where R50 is less than 0.667 or 1.500 or more In the case of the adjacent area A, the number ratio of the adjacent areas A is 30% or more in either the hairline direction and the hairline orthogonal direction.

(A) Sa (1 µm) h means a roughness profile having a length of 1000 µm in the direction of the hairline, and 10 points at the top of the convex part at the highest position among the peaks of the convex part in the roughness profile. On the other hand, the three-dimensional average surface roughness Sa (1 μm) of a region of 1 μm×1 μm around each of the convex portions is measured, and the minimum value of the measured three-dimensional average surface roughness Sa (1 μm) is shown. .

(B) Sa (1 µm) s is a measurement of a roughness profile of 1000 µm in the direction of the hairline, and the 10 points of the concave apex at the lowest position among the concave vertexes in the roughness profile On the other hand, the three-dimensional average surface roughness Sa (1 μm) of a region of 1 μm×1 μm around each of the concave portions is measured, and the maximum value of the measured three-dimensional average surface roughness Sa (1 μm) is shown. .

(2) The zinc-based electroplated steel sheet described in (1) may further include, as an upper layer of the zinc-based electroplating layer, an organic resin coating layer having light transmission properties and a thickness of 10 μm or less.

(3) In the zinc-based electroplated steel sheet described in (2), the organic resin coating layer contains a colorant, and the color difference according to the L ^* a ^* b ^* color system of the organic resin coating layer is determined using a CIE standard light source D65. When measured by the specular reflection light removal method using, the value of (a ^{* 2} + b ^{* 2} ) ^0.5 indicating saturation may be 10 or less.

(4) In the zinc-based electroplated steel sheet according to (2) or (3), surface roughness Ra (CC) measured along the hairline orthogonal direction in the presence of the organic resin coating layer, and the organic resin The surface roughness Ra (MC) of the zinc-based electroplating layer measured along the hairline orthogonal direction after peeling the coating layer may satisfy the relationship represented by the following formula (1).

Ra(CC)<Ra(MC)<5×Ra(CC)… Equation (1)

(5) In the zinc-based electroplated steel sheet according to any one of (1) to (4), the base iron exposure rate of the zinc-based electroplating layer may be less than 5%.

(6) In the zinc-based electroplated steel sheet according to any one of (1) to (5), the adhesion amount of the zinc-based electroplating layer may be 10 g/m 2 to 60 g/m 2.

(7) In the zinc-based electroplated steel sheet according to any one of (1) to (6), both of the zinc-based electroplating layer or the organic resin coating layer and the zinc-based electroplating layer provided as an upper layer of the zinc-based electroplating layer The surface roughness Ra of the steel sheet after removal of? May be 1.0 µm or more and 1.7 µm or less.

(8) In the zinc-based electroplated steel sheet according to any one of (1) to (7), the zinc-based electroplating layer contains 5 masses in total of any one or more elements selected from the group consisting of Fe, Ni, and Co. You may contain% to 20 mass %.

(9) In the zinc-based electroplating steel sheet according to any one of (1) to (8), both of the zinc-based electroplating layer or the organic resin coating layer and the zinc-based electroplating layer provided as an upper layer of the zinc-based electroplating layer The surface roughness Ra of the steel sheet after removal of? May be 60% or less of the thickness of the zinc-based electroplating layer.

As described above, according to the present invention, it is possible to achieve a hairline appearance, excellent metallic feel, suppress excessive increase in gloss, and achieve film adhesion when a resin film is formed on the upper layer of plating.

1A is an explanatory view schematically showing an example of a structure of a zinc-based electroplated steel sheet according to an embodiment of the present invention.
1B is an explanatory view schematically showing an example of the structure of a zinc-based electroplated steel sheet according to the embodiment.
FIG. 2A is an example of an image when the surface of a zinc-based electroplating layer included in the zinc-based electroplated steel sheet according to the embodiment is observed with a scanning electron microscope (SEM).
2B is an example of an image when the surface of a zinc-based electroplating layer of the zinc-based electroplated steel sheet according to the embodiment is observed with a normal camera.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in the present specification and drawings, elements having substantially the same functional configuration are denoted by the same numerals, so that redundant descriptions are omitted.

(About the entire composition of zinc-based electroplated steel sheet)

Hereinafter, the entire configuration of a zinc-based electroplated steel sheet according to an embodiment of the present invention will be described in detail with reference to FIGS. 1A and 1B. 1A and 1B are explanatory diagrams schematically showing an example of the structure of a zinc-based electroplated steel sheet according to the present embodiment.

The zinc-based electroplated steel sheet according to the present embodiment has at least a steel sheet as a base material and a zinc-based electroplating layer positioned on either surface of the steel sheet, and hairline processing is performed on the surface of the zinc-based electroplating layer.

In general hairline processing, a smoothing portion corresponding to a hairline (that is, a portion that has been crushed and smoothed by hairline processing) is provided to be physically continuous along a predetermined direction, and the continuation of this smoothing portion is recognized as a hairline. . However, the hairline processing performed on the surface of the zinc-based electroplating layer according to the present embodiment is determined when a person observes the surface of the zinc-based electroplating layer according to the present embodiment, even though the smoothing portion is not physically continuous. It has the characteristic of recognizing that the hairline is connected in the direction of. Hereinafter, the zinc-based electroplated steel sheet according to the present embodiment having such characteristics will be described in detail.

As schematically shown in FIG. 1A, the zinc-based electroplated steel sheet 1 according to the present embodiment includes a steel sheet 11 as a base material and a zinc-based electroplating layer located on either surface of the steel sheet 11 ( 13) has at least. In addition, as shown in FIG. 1B, it is preferable that the zinc-based electroplated steel sheet 1 according to the present embodiment further has a light-transmitting organic resin coating layer 15 on the surface side of the zinc-based electroplating layer 13. Do.

<About the description>

The steel sheet 11, which is the base material of the zinc-based electroplated steel sheet 1 according to the present embodiment, is not particularly limited, and various known types according to the mechanical properties (for example, tensile strength, etc.) required for the zinc-based electroplated steel sheet. It is possible to use a steel plate appropriately.

[About the surface shape of the substrate]

In the zinc-based electroplated steel sheet 1 according to the present embodiment, the zinc-based electroplating layer 13, or the organic resin coating layer 15 and the zinc-based electroplating layer located on the upper side of the zinc-based electroplating layer 13 ( It is preferable that the surface roughness Ra of the steel sheet 11 after removing both sides of 13) is 1.0 µm or more and 1.7 µm or less. Here, Ra is the arithmetic mean roughness specified in JIS B 0601:2013. When the surface roughness Ra is less than 1.0 µm, it is not preferable because there is a possibility that it may become difficult to provide the zinc-based electroplating layer 13 having a surface shape described in detail below. When the surface roughness Ra exceeds 1.7 μm, there is a possibility that it is difficult to recognize that the hairline is stretched in a predetermined direction even if the zinc-based electroplating layer 13 having a surface shape described in detail below is provided. Because it is not desirable.

In the steel sheet 11 according to the present embodiment, both of the zinc-based electroplating layer 13 or the organic resin coating layer 15 and the zinc-based electroplating layer 13 positioned on the upper side of the zinc-based electroplating layer 13 It is more preferable that the surface roughness Ra of the steel sheet 11 after removal of is not less than 1.1 µm and not more than 1.5 µm.

In addition, in the present invention, the surface roughness Ra is not significantly different in the direction orthogonal to the hairline and the direction in which the hairline is recognized as being stretched, but the range of the surface roughness Ra is in a direction orthogonal to the hairline. Measure.

In addition, the surface roughness Ra of the steel sheet 11 is the zinc-based electroplating layer 13 or both of the organic resin coating layer 15 and the zinc-based electroplating layer 13 located on the upper side of the zinc-based electroplating layer 13. After removal, it is preferable to be 60% or less of the thickness of the zinc-based electroplating layer 13. When the surface roughness Ra is more than 60% of the thickness of the zinc-based electroplating layer 13, it is preferable because there is a possibility of impairing corrosion resistance when the zinc-based electroplating layer 13 having a surface shape described in detail below is provided. Not.

In the steel sheet 11 according to the present embodiment, both of the zinc-based electroplating layer 13 or the organic resin coating layer 15 and the zinc-based electroplating layer 13 positioned on the upper side of the zinc-based electroplating layer 13 It is more preferable that the surface roughness Ra of the steel sheet 11 after removal is 40% or less of the thickness of the zinc-based electroplating layer 13.

In addition, the thickness of the zinc-based electroplating layer 13 is determined as follows. First, the galvanized steel sheet is immersed in an acid solution containing an inhibitor to dissolve the zinc-based electroplating layer 13. Next, the thickness of the zinc-based electroplating layer 13 is converted from the adhesion amount of the zinc-based electroplating layer 13 thus obtained and the specific gravity of the metal contained in the zinc-based electroplating layer 13.

Further, the surface roughness Ra of the steel sheet 11 after removing both the zinc-based electroplating layer 13 or the organic resin coating layer 15 and the zinc-based electroplating layer 13 formed as an upper layer of the zinc-based electroplating layer 13 is, When it falls within the above range, the surface roughness Ra of the steel sheet 11 before forming the zinc-based electroplating layer 13 or the organic resin coating layer 15 is also within the above range.

The surface roughness Ra as described above can be measured with a stylus type roughness meter. Here, when measuring the surface roughness of the steel sheet 11 after forming the zinc-based electroplating layer 13 or the organic resin coating layer 15 to be described later, a zinc-based electroplating layer with a release agent such as a solvent or remover that does not corrode the steel sheet. After removing (13) or the organic resin coating layer 15, the surface roughness Ra may be measured.

<About zinc-based electroplating layer>

Further, a zinc-based electroplating layer is formed on one surface of the steel sheet 11 as described above. The zinc-based electroplating layer 13 according to the present embodiment is a smooth portion visually recognized as a hairline extending in a predetermined direction (a direction indicated by an arrow in the lower part of FIG. 1A), as schematically shown in FIG. 1A. It has 103 and grandfathers 101a and 101b that are visually recognized as non-hairline parts. Here, in the following description, ``the direction in which the hairline is recognized as being stretched'' is abbreviated as ``the direction of the hairline,'' and ``the direction perpendicular to the direction in which the hairline is stretched in the direction viewed'' Direction”.

In Fig. 1A, the rough portion 101a is a concave portion, and is a portion avoiding the influence of polishing or the like accompanying the hairline processing. In addition, the rough portion 101b is a portion of the zinc-based electroplating layer 13 that remains after hairline processing even though its surface is located at a position away from the surface of the steel sheet 11 in the depth direction, and usually, the rough portion 101b The part of is also continuous over a certain range in the direction of the hairline. In the roughened portion 101b of FIG. 1A, it is schematically illustrated that there may be a roughened portion also in the surface portion of the zinc-based electroplating layer 13. In addition, the coarse portion and the smoothing portion will be described in detail later.

[Type and composition of zinc-based electroplating layer]

As the zinc-based electroplating layer 13 according to the present embodiment, electro-galvanizing or electro-zinc alloy plating (hereinafter, referred to as "zinc-based electroplating") is used.

First, with respect to the plated metal, since the sacrificial corrosion resistance is inferior in plating other than zinc-based plating, it is not suitable for use in which the cut cross section is unavoidably exposed in use. In addition, if the zinc concentration in the zinc-based electroplating layer 13 is too low, the sacrificial anticorrosive ability is lost, so it is preferable that the zinc alloy plating contains 65% by mass or more of zinc with respect to the total mass of the zinc-based electroplating layer 13 .

As a plating method, in addition to electroplating, there are a hot-dip plating method, a thermal spray method, a vapor deposition plating method, and the like. However, the hot-dip plating method is unsuitable because the appearance quality is degraded by solidification patterns such as sequins or dross inevitably mixed in the plating layer. Further, in the thermal spraying method, the uniformity of the appearance cannot be ensured due to the voids inside the plated film, which is unsuitable. Further, the vapor deposition method is unsuitable because the film formation speed is low and productivity is insufficient.

Therefore, in the zinc-based electroplated steel sheet 1 according to the present embodiment, electroplating is used to perform zinc-based plating on the surface of the steel sheet.

Here, in the case of forming the zinc-based electroplating layer 13 according to this embodiment by using electro zinc alloy plating, such electro zinc alloy plating is Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo It is preferable to include at least one element selected from the element group consisting of V, W, and Zr, and Zn. In particular, it is preferable that the electro zinc alloy plating contains 5% by mass or more and 20% by mass or less in total of at least one element selected from the element group consisting of Fe, Ni, and Co. When electro-zinc alloy plating contains at least one element selected from the element group consisting of Fe, Ni, and Co within the range of the total content, it becomes possible to realize more excellent corrosion resistance.

Electro zinc plating and electro zinc alloy plating may contain impurities. Here, impurities are not consciously added as a zinc-based electroplating component, but are incorporated in the raw material or in the manufacturing process, and are Al, Mg, Si, Ti, B, S, N, C, Nb, Pb. , Cd, Ca, Pb, Y, La, Ce, Sr, Sb, O, F, Cl, Zr, Ag, W, H, and the like. In addition, when electro-galvanizing is carried out, Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, Zr are mixed as impurities, although it varies depending on the type of electroplated steel sheet manufactured in the same manufacturing facility. There are cases. In the present embodiment, even if the impurities are present in a total of about 1% by mass relative to the total mass of the plating, the effect obtained by plating is not impaired.

In addition, in the zinc-based electroplating layer 13 of the present invention, if the Zn content is excessively reduced, the sacrificial anticorrosive performance is lowered. Therefore, the Zn content in the zinc-based electroplating layer 13 is With respect to the mass, it is preferably 65% or more as described above, more preferably 70% or more, and particularly preferably 80% or more.

The composition of the zinc-based electroplating layer 13 can be analyzed by the following method, for example. In other words, after removing the organic resin film layer with a release agent such as a solvent or remover that does not corrode the plating (for example, Neo River S-701: manufactured by Sansai Chemical Co., Ltd.), the zinc-based electroplating layer is dissolved with hydrochloric acid containing an inhibitor. Then, the composition of the zinc-based electroplating layer 13 may be analyzed by an ICP (Inductively Coupled Plasma) emission spectroscopic analyzer.

[About the adhesion amount of the zinc-based electroplating layer 13]

It is preferable that the adhesion amount of the zinc-based electroplating layer according to the present embodiment is 10 g/m 2 or more. If desired corrosion resistance can be ensured, the amount of zinc-based electroplating layer deposited is irrelevant. However, if the amount of zinc-based electroplating layer deposited is less than 10 g/m2, it is preferable that the base iron exposure rate is likely to exceed 5% when applying the hairline. Not.

The adhesion amount of the zinc-based electroplating layer is more preferably 15 g/m 2 or more, and still more preferably 20 g/m 2 or more. In addition, the upper limit of the amount of the zinc-based electroplating layer is not particularly defined, and may be appropriately determined in consideration of the manufacturing cost of the plated steel sheet according to the present embodiment, and may be, for example, about 60 g/m 2.

[About the subway exposure rate]

The zinc-based electroplated steel sheet 1 according to the present embodiment assumes that the surface of the zinc-based electroplated layer 13 is subjected to hairline processing by polishing or the like. For this reason, a part of the zinc-based electroplating layer 13 may be removed in a process step such as polishing, and the base iron (that is, the steel sheet 11) may be partially exposed depending on the polishing/grinding thickness.

It is preferable that the base iron exposure rate of the zinc-based electroplating layer 13 according to the present embodiment is less than 5%. In this embodiment, the corrosion resistance is sufficiently secured by zinc or zinc alloy plating, but when the base iron is exposed at the time of application of the hairline, long-term corrosion resistance may decrease due to the effect of galvanic corrosion, which is not preferable. . In the present embodiment, since the base iron exposure rate of the zinc-based electroplating layer 13 is less than 5%, it is excellent in long-term corrosion resistance in addition to moderate corrosion resistance generally required for a steel sheet, and thus has extremely good corrosion resistance.

The base iron exposure rate of the zinc-based electroplating layer 13 is more preferably 3% or less, and still more preferably 0%.

In addition, the base iron exposure rate was determined by EPMA analysis of 5 random squares with 1 mm side after removing the organic resin coating layer 15 with a release agent such as a solvent or remover that does not corrode the plating, and Zn for the analyzed area The area ratio not detected can be determined by image analysis.

Since specific hairline processing is performed on the surface of the zinc-based electroplating layer 13 according to the present embodiment, the surface has a characteristic surface shape accompanying the hairline processing. This surface shape will be described in detail below again.

<About the organic resin coating layer>

It is preferable that the surface of the zinc-based electroplating layer 13 provided with the hairline as described above is coated with a transparent resin (in other words, a resin having translucency) as schematically shown in Fig. 1B. That is, it is preferable that the organic resin coating layer 15 is provided on the surface side of the zinc-based electroplating layer 13 according to the present embodiment. Here, in this embodiment, ``the resin has light transmission property'' means that light is irradiated on the surface of the zinc-based electroplated steel sheet 1 and the zinc-based electroplated steel sheet 1 is observed at an angle of 10° from the vertical direction. At this time, it means that the hairline applied to the zinc-based electroplating layer 13 can be visually recognized.

[About the components of the organic resin coating layer]

The resin used for forming the organic resin coating layer 15 is not particularly limited as long as it maintains sufficient transparency. Examples of resins used in the formation of the organic resin coating layer 15 include polyester resins, epoxy resins, urethane resins, polyester resins, phenol resins, polyethersulfone resins, melamine alkyd resins, and acrylic resins. Resin, polyamide resin, polyimide resin, silicone resin, polyvinyl acetate resin, polyolefin resin, polystyrene resin, vinyl chloride resin, vinyl acetate resin, and the like.

In addition, as a means for improving the adhesion between the organic resin coating layer 15 and the zinc-based electroplating layer 13, a plated steel sheet comprising the steel sheet 11 and the zinc-based electroplating layer 13 within a range not impairing the appearance. On the other hand, inorganic treatment, organic-inorganic composite treatment, surface modification treatment, or the like may be performed. Here, "damaging the appearance" means reducing the metallic feel, such as reducing the transparency, causing gloss unevenness, or creating an abnormal feeling of irregularities. Examples of such treatment include Zr oxide treatment, Zn oxide treatment, silane coupling agent treatment, weak acid immersion treatment, weak alkali immersion treatment, and the like.

In order to add desired performance to the organic resin coating layer 15, various additives may be contained within a range that does not impair light transmission and appearance, and does not deviate from the range specified in the present invention. As the performance added to the organic resin coating layer 15, for example, corrosion resistance, slip mobility, scratch resistance, conductivity, color tone, and the like can be mentioned. For example, if it has corrosion resistance, it may contain a rust inhibitor or inhibitor, if it has slip mobility or scratch resistance, it may contain wax or beads, if it is conductive, it may contain a conductive agent, and if it is a color tone, it may contain a known pigment or dye. You may contain a coloring agent.

In addition, when a known colorant such as a pigment or a dye is contained in the organic resin coating layer 15 according to the present embodiment, it is preferable to contain a colorant to such an extent that the hairline can be visually recognized and the metallic feel is not lost. Here, the degree to which the hairline can be visually recognized and the metallic feel is not lost is the color tone (L ^* a ^* ) of the organic resin coating layer 15 in a 10 degree field of view by a commercially available color difference meter using the CIE standard light source D65. When b ^* color tone) is measured by the SCE (Specula Component Excluded) method, it means the range in which the relationship of saturation (a ^*2 +b ^*2 ) ^0.5 ≤10 is established.

[About the thickness of the organic resin coating layer]

It is preferable that the thickness of the organic resin coating layer 15 according to the present embodiment is 10 µm or less. When the thickness of the organic resin coating layer 15 exceeds 10 μm, the distance through which the light passes through the organic resin coating layer 15 becomes longer, so that the reflected light decreases and the gloss in the direction of the hairline decreases. It is not preferable because the possibility of becoming difficult to do becomes high. Further, due to the deformation of the resin accompanying the processing, a shift in the texture of the surface of the zinc-based electroplating layer 13 and the shape of the surface of the organic resin coating layer 15 tends to occur, which is not preferable.

For the above reasons, the thickness of the organic resin coating layer 15 is preferably 10 µm or less, and more preferably 8 µm or less.

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

The thickness of the thinnest portion of the organic resin coating layer 15 is more preferably 0.5 μm or more, and more preferably the average thickness of the organic resin coating layer 15 is 3.0 μm or more.

In the above, the entire configuration of the zinc-based electroplated steel sheet 1 according to the present embodiment has been described in detail. 1A and 1B show a case in which the zinc-based electroplating layer 13 and the organic resin coating layer 15 are formed on one surface of the steel sheet 11, but two of the steel sheets 11 opposing each other. The zinc-based electroplating layer 13 and the organic resin coating layer 15 may be formed on the surface.

(About the surface shape of the zinc-based electroplating layer 13)

Next, the surface shape of the zinc-based electroplating layer 13 according to the present embodiment will be described in detail with reference to Fig. 1A.

As described above, the zinc-based electroplating layer 13 according to the present embodiment has a smoothing portion 103 for forming a hairline and rough portions 101a and 101b in the surface layer portion as described above. The rough portions 101a and 101b originate from the microscopic surface shape of the zinc-based electroplating layer 13.

In this embodiment, the roughness 101a, 101b is a part with a high detection frequency of the microscopic grandfather whose three-dimensional illuminance Sa (1 μm) in a microscopic region of 1 μm×1 μm is more than 200 nm and 2000 nm or less. The smoothing portion 103 is a portion with a high detection frequency of the microscopic smoothing portion in which the three-dimensional roughness Sa (1 μm) of the microscopic region of 1 μm×1 μm becomes more than 5 nm and 200 nm or less.

Here, the three-dimensional roughness Sa is the arithmetic mean height defined in ISO 25178, which is obtained by extending Ra (the arithmetic mean height of a line) prescribed in JIS B0601:2013 to the plane.

Here, in this embodiment, "microscopic grandfather", "microscopic smoothing part", "grandfather 101a, 101b", and "smoothing part 103" were defined as follows.

First, in the zinc-based electroplating layer 13 according to the present embodiment, the display resolution in the height direction is 10 nm or more and the display resolution in the width direction is 10 nm or more (that is, the display resolution in the height direction and the width direction). Using a laser microscope superior to this 10 nm), the surface of the zinc-based electroplating layer 13 in the range of 1 cm x 1 cm at 500 times the magnification is observed. Here, when the observation field of view of the laser microscope does not reach 1 cm×1 cm, a plurality of fields of view may be observed, and the plurality of fields of view may be connected to observe the surface.

Next, a region in which the three-dimensional roughness Sa (1 µm)h of a 1 µm×1 µm region is more than 200 nm and not more than 2000 nm was referred to as "microscopic roughness". Similarly, a region in which the three-dimensional roughness Sa (1 µm) s in a region of 1 µm x 1 µm with the formation of the hairline became more than 5 nm and not more than 200 nm was designated as a "microscopic smoothing part".

Here, the three-dimensional roughness Sa (1 μm)h is defined as follows (A), and the three-dimensional roughness Sa (1 μm)s is defined as follows (B).

(A) Sa (1 µm) h means a roughness profile having a length of 1000 µm in the hairline direction, and each of the 10 convex vertices at the highest position among the convex vertices in the profile. The three-dimensional average surface roughness Sa (1 µm) of a 1 µm×1 µm area was measured around the apex of the convex portion of, and the minimum value in the measured three-dimensional average surface roughness Sa (1 µm) was shown.

(B) Sa (1 µm) s is a measurement of a roughness profile of 1000 µm in length in the hairline direction, and each of the 10 concave vertices at the lowest position among concave vertices in the profile. The three-dimensional average surface roughness Sa (1 µm) of a 1 µm×1 µm region centered on the concave apex of is measured, and the maximum value in the measured three-dimensional average surface roughness Sa (1 µm) is shown.

In addition, the definition is that in the schematic diagrams Figs. 1A and 1B, a portion of the smoothing portion indicated by reference numeral 103 has a portion in which Sa(1 μm)s exceeds 200 nm, but the grandfather indicated by reference numerals 101a and 101b In some cases, it is not excluded that there is a portion in which Sa(1 μm)h is less than 200 nm.

In the zinc-based electroplating layer 13 according to the present embodiment, the rough portions 101a and 101b correspond to portions in which the plated crystal grains are present in a state close to an electroplated stone or an electroplated stone. The smoothing portion 103 corresponds to a portion where the plated crystal grains are crushed due to the formation of the hairline, or a portion where the shape of the crystal grains does not exist.

In the zinc-based electroplating layer 13 according to the present embodiment, the fine regions (i.e., microscopic roughness) in which the plated crystal grains remain are frequently present, and A smoothing portion 103 having a high frequency of existence of a fine region (ie, a microscopic smoothing portion) in which the shape of crystal grains does not remain, is present at an appropriate ratio and position as described later. Thereby, while realizing the improvement of metallic feeling in the smoothing part 103, in the rough part 101a, 101b, it is compared with the organic resin coating layer 15 which is preferably provided on the upper layer of the zinc-based electroplating layer 13 It realizes suitable adhesion to the processed part and suppression of excessive increase in gloss.

Hereinafter, even when the organic resin coating layer 15 is present on the upper layer of the zinc-based electroplating layer 13, the zinc-based electroplating layer 13 is applied to both the suitable metallic feel and the adhesion of the processed part and suppression of excessive increase in gloss. Various required conditions will be described in detail.

[Distribution of Grandfather and Smoothing Part]

In the zinc-based electroplating layer 13 according to the present embodiment, if the smoothing portion 103 is continuously present over a long distance in the hairline direction, the gloss becomes too high, which is not preferable. On the other hand, if the grandfather portions 101a and 101b are excessively continuous, the continuity of the hairline is impaired, which is not preferable. Therefore, it is important that the smoothing portion 103 forming the hairline is divided by the rough portions 101a and 101b at an appropriate ratio.

When measuring the three-dimensional average surface roughness Sa (50 μm) in a region of 50 μm×50 μm using a laser microscope having a display resolution of 10 nm or more in the height direction and 10 nm or more in the width direction, microscopic The three-dimensional average surface roughness Sa (50 µm) of the region in which there are many smooth parts and less microscopic roughness is calculated. Conversely, the three-dimensional average surface roughness Sa (50 µm) of a region in which there are many microscopic roughness and less microscopic smoothing is calculated. Therefore, if a region having a high three-dimensional average surface roughness Sa (50 µm) or a region having a low three-dimensional average surface roughness Sa (50 µm) is continuous, it is assumed that the smoothing portion 103 or the rough portions 101a, 101b are continuous. I can judge.

Here, "the area in which the three-dimensional average surface roughness Sa (50 µm) is high, or the region where the three-dimensional average surface roughness Sa (50 µm) is low is continuous" means that it is three-dimensional along the hairline direction or the hairline orthogonal direction. When the average surface roughness Sa (50㎛) was continuously measured, R50, which is the ratio of the three-dimensional average surface roughness Sa (50㎛), was calculated in two neighboring regions (hereinafter, sometimes referred to as adjacent regions). When the value of R50 is in the range of 0.667 to less than 1.500.

In the zinc-based electroplating layer 13 according to the present embodiment, the three-dimensional average surface roughness Sa (50 μm) was measured in n locations in the hairline direction, and the three-dimensional average surface roughness Sa in the adjacent region in the hairline direction When the value of the ratio R50 of (50㎛) is calculated at the (n-1) location, the value of the ratio R50 (in other words, the value of the ratio R50 is less than 0.667 or 1.500 or more) where 0.667 or more and less than 1.500 are out of the range The number ratio of adjacent areas less than 0.667 or 1.500 or more is sometimes referred to as adjacent area A) is 30% or more (that is, (number of adjacent areas A)/(n-1) is 0.3 or more). In other words, the ratio of the number of adjacent areas (hereinafter, referred to as adjacent areas B in some cases) with R50 of 0.667 or more and less than 1.500 is less than 70%.

When the ratio of the number of adjacent regions A in the hairline direction is less than 30% (that is, the ratio of the number of adjacent regions B is 70% or more), the smoothing portion 103 is too continuous and the gloss is too high, and the organic resin coating layer 15 ), the adhesion of the processed part is lowered, or the coarse parts 101a and 101b are too continuous, so that it cannot be recognized as a continuous hairline, and the gloss in the direction of the hairline is excessively reduced, thereby damaging the metallic feel. Because it is not desirable.

On the other hand, there is no upper limit of the number ratio of the adjacent regions A in the hairline direction, and the number ratio may be 100%.

By setting the number ratio of the adjacent regions A in the hairline direction to 30% or more, gloss can be appropriately suppressed without impairing the metallic feel, and excellent film adhesion can be realized. The number ratio is preferably 35% or more, and more preferably 40% or more.

Also in the direction perpendicular to the hairline, as in the direction of the hairline, the ratio of the number of adjacent regions A is set to 30% or more. Even when the ratio of the number of adjacent regions A in the hairline orthogonal direction is less than 30%, the smoothing portion 103 is too continuous, so that the gloss is too high, and the adhesion of the processed portion when the organic resin coating layer 15 is provided decreases, or It is not preferable because the grandfathers 101a and 101b are too continuous to be recognized as a hairline.

On the other hand, there is also no upper limit for the ratio of the number of adjacent regions A in the direction perpendicular to the hairline, and the number ratio may be 100%.

By setting the number ratio to 30% or more, gloss can be appropriately suppressed without impairing the metallic feel, and excellent film adhesion can be realized.

The number ratio is preferably 35% or more, and more preferably 40% or more.

In addition, in the present invention, the ratio of the number of adjacent regions A in the hairline direction and the hairline orthogonal direction is 30% or more, and for example, as shown in FIG. 1A, irregularities are provided to the cross-sectional shape of the zinc-based electroplating layer 13 As a method for blocking the continuity of the hairline, the polishing/grinding thickness to the roughness of the steel plate is limited to a predetermined ratio as described later. Further, as described above, it is preferable to set the surface roughness Ra of the steel sheet 11 as a base material to a specific range.

[About the surface roughness in the rough portions 101a and 101b]

As described above, in the zinc-based electroplating layer 13 according to the present embodiment, as a result of setting the number ratio of adjacent regions A to 30% or more, there are a large number of microscopic roughnesses as described above, and an area in which there is little microscopic smoothing. (That is, grandfathers 101a and 101b) exist in an appropriate proportion. Thereby, the film adhesion when the organic resin coating layer 15 is provided on the upper layer of the zinc-based electroplating layer 13 is ensured.

Therefore, the zinc-based electroplating layer 13 according to the present embodiment uses a laser microscope having a display resolution in the height direction of 1 nm or more and a display resolution in the width direction of 1 nm or more, using a laser microscope in an area of 1 μm×1 μm. When the dimensional average surface roughness Sa (1 µm) is measured, Sa (1 µm) h defined in (A) above has a microscopic roughness of more than 200 nm and not more than 2000 nm.

In addition, in the zinc-based electroplated steel sheet 1 according to the present embodiment, it is preferable to set the surface roughness Ra of the steel sheet 11 as a base material in a specific range as described above. This is because an electroplating layer is deposited in the valley portion (concave portion) in the roughness curve (roughness profile), and as a result of the portion being protected from polishing or the like, microscopic roughness is secured at least in the roughness portion 101a. .

When Sa (1 µm)h of the microscopic roughness is more than 200 nm and not more than 2000 nm, it is possible to realize an excellent film adhesion, and a contact state with the organic resin coating layer 15 can be realized more reliably.

[About the surface roughness in the smooth part]

In addition, as mentioned above, in the zinc-based electroplating layer 13 according to the present embodiment, since the smoothing portion 103 is present in an appropriate ratio, the zinc-based electroplated steel sheet 1 according to the present embodiment is suitable metallic I have a sense. Here, in order to realize the effect of improving the metallic feel by the smoothing portion 103, it is preferable that the smoothing portion 103 has an appropriate surface roughness and an area of an appropriate area.

Therefore, the zinc-based electroplating layer 13 according to the present embodiment uses a laser microscope having a display resolution of 1 nm or more in the height direction and a display resolution of 1 nm or more in the smooth portion 103 in the width direction of 1 μm. When measuring the three-dimensional average roughness Sa (1 µm) in a region of × 1 µm, Sa (1 µm) s defined in (B) above has a microscopic smoothing portion of more than 5 nm and not more than 200 nm.

Since the smoothing portion 103 has a high detection frequency of the microscopic smoothing portion, it is possible to achieve both a suitable metallic feel and a suitable glossiness.

[Surface roughness of zinc-based electroplating layer before and after formation of organic resin coating layer]

In addition, in the zinc-based electroplating layer 13 according to the present embodiment, in the state in which the organic resin coating layer 15 is present, the surface roughness Ra (CC) (unit: µm) measured along the direction perpendicular to the hairline, and The surface roughness Ra (MC) [unit: µm] of the zinc-based electroplating layer 13 measured along the hairline orthogonal direction after peeling the organic resin coating layer 15 is expressed by the following equation (101). It is desirable to satisfy the relationship.

Ra(CC)<Ra(MC)<5×Ra(CC)… Equation (101)

Here, each Ra in the above formula (101) is an average value of 6 locations excluding the maximum side 2 locations and the minimum side 2 locations by measuring 10 arbitrary locations.

When the surface roughness Ra(MC) and Ra(CC) satisfy the relationship expressed by the above formula (101), it becomes possible to realize a metallic feel more reliably while having a hairline appearance.

The surface roughness Ra(MC) and Ra(CC) more preferably satisfy the relationship represented by the following equation (103).

1.5×Ra(CC)<Ra(MC)<3.0×Ra(CC)… Equation (103)

In addition, as described above, the surface roughness Ra in each direction can be measured with a stylus type roughness meter. Here, when measuring the surface roughness of the zinc-based electroplating layer 13 after forming the organic resin coating layer 15 described later, the organic resin coating layer 15 is removed with a release agent such as a solvent or remover that does not corrode the plating. Then you can do the measurements.

In the above, the surface shape of the zinc-based electroplating layer 13 according to the present embodiment has been described in detail with reference to Fig. 1A.

(About the manufacturing method of zinc-based electroplated steel sheet)

Subsequently, a method of manufacturing the zinc-based electroplated steel sheet according to the present embodiment as described above will be briefly described.

In the following, first, a method of manufacturing a zinc-based electroplated steel sheet having a structure as shown in FIGS. 1A and 1B will be briefly described.

First, the steel sheet whose surface roughness is adjusted to fall within a predetermined range is subjected to degreasing with an alkali solution and pickling with an acid using hydrochloric acid or sulfuric acid to form a zinc-based electroplating layer. Here, for the adjustment of the surface roughness of the steel sheet, a known method can be used. For example, a method of rolling and transferring with a roll adjusted so that the surface roughness is in a desired range can be used.

As a method of forming the zinc-based electroplating layer 13, a known electroplating method can be used.

As the electroplating bath, for example, a sulfuric acid bath, a chloride bath, a zincate bath, a cyanide bath, a pyrophosphate bath, a boric acid bath, a citric acid bath, other complex baths, and combinations thereof can be used.

In addition to Zn ions in the electro zinc alloy plating bath, by adding one or more single ions or complex ions selected from Co, Cr, Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, and Zr, Co, Cr , Cu, Fe, Ni, P, Sn, Mn, Mo, V, W, Zr, it is possible to form an electro zinc alloy plating layer containing a desired amount. It is more preferable to add an additive to the plating bath in order to stabilize the ions in the plating bath or to control the plating characteristics.

The composition of the electroplating bath, the temperature, the flow rate, and the current density at the time of plating, the current pattern, etc. may be appropriately selected so as to obtain a desired plating composition, and are not particularly limited. Further, the thickness of the zinc plating layer and the electro zinc alloy plating layer can be controlled by adjusting the current value and time within the range of the current density at which the zinc plating layer or the electro zinc alloy plating layer has a desired composition.

With respect to the steel sheet 11 provided with the obtained zinc-based electroplating layer 13, a hairline according to the present embodiment is formed. As for the method of applying the hairline, a method of polishing with a polishing belt, a method of polishing with an abrasive brush, a method of polishing with a polishing/grinding machine, and the like can be mentioned.

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

Here, in the polishing treatment as described above, the concave portion in which the plated crystal grains are present is maintained as it is or the concave portion is appropriately ground, so that the smoothing portion as schematically shown in Figs. 1A and 1B ( The grandfathers 101a and 101b may be present to divide 103).

In the zinc-based electroplating layer 13 according to the present embodiment, the surface roughness Ra of the steel sheet 11 is applied to the surface by setting the polishing/grinding thickness (i.e., polishing/grinding rate) at the time of hairline formation to 10 to 80%. You can create the desired hairline. Here, the polishing/grinding rate is an amount expressed by the length in the depth direction starting from the surface of the zinc-based electroplating layer 13 by how much the zinc-based electroplating layer 13 has been polished and ground with respect to the surface roughness of the steel sheet. The polishing/grinding thickness can be changed by adjusting the grain size, rolling force and number of polishing of the polishing paper.

By forming the hairline at a polishing/grinding rate of 10 to 80%, the hairline is formed while the irregularities on the surface of the steel plate 11 as the base material remain, even though the smoothing portion is not physically continuous. And, it is possible to form a hairline that is connected in a predetermined direction.

When the polishing/grinding rate is less than 10%, it is not preferable because there is a high possibility that the number ratio of the adjacent regions A in the hairline direction and/or the hairline orthogonal direction will be less than 30%. The polishing/grinding rate is 10% or more, preferably 20% or more, and more preferably 30% or more.

If the polishing/grinding rate is more than 80%, it is not preferable because there is a high possibility that the number ratio of the adjacent regions A in the hairline direction and/or the hairline orthogonal direction will be less than 30%. The polishing/grinding rate is 80% or less, preferably 70% or less, and more preferably 60% or less.

The surface roughness Ra of the steel plate 11 can be measured with an acceleration type roughness meter as described above. In addition, the polishing/grinding rate is calculated from the difference in the amount of plating between the two adjacent locations, with a hairline provided on one side and no hairline on the other. Further, in the case of the zinc-based electroplating layer according to the present embodiment, a specific gravity of 7.1 is used when converting from adhesion amount to length.

The surface of the zinc-based electroplating layer 13 provided with a hairline is coated with an organic resin as necessary. Here, the paint used to form the organic resin coating layer 15 follows the surface shape of the zinc-based electroplating layer 13 at the moment it is applied to the zinc-based electroplating layer 13, and once, the zinc-based electroplating layer 13 It is preferable that the leveling after reflecting the surface shape of is slow. That is, it is preferable that the coating material has a low viscosity at a high shear rate and a high viscosity at a low shear rate. Specifically, it is preferable to have a viscosity of 10 [Pa·s] or more at a shear rate of 0.1 [1/sec], and a shear viscosity of 0.01 [Pa·s] or less at a shear rate of 1000 [1/sec].

In order to adjust the shear viscosity in the above range, for example, if it is a paint using an aqueous emulsion resin, it can be adjusted by adding a hydrogen bonding viscosity modifier. Such a hydrogen bonding viscosity modifier can increase the viscosity of the paint because it is constrained by hydrogen bonds at a low shear rate, but the viscosity decreases because hydrogen bonds are cut at a high shear rate. This makes it possible to adjust the shear viscosity according to the required coating conditions.

The method of coating the organic resin is not particularly limited, and a known method can be used. For example, it can be formed by natural drying or baking drying after applying by a spray method, a roll coater method, a curtain coater method, a die coater method, or an immersion pull method using a paint adjusted to the viscosity as described above. Further, the drying temperature and drying time, and the baking temperature and baking time may be appropriately determined so that the organic resin coating layer 15 to be formed has desired performance. At this time, if the temperature increase rate is low, the time from the softening point of the resin component to the completion of baking increases and leveling proceeds. Therefore, it is preferable that the temperature increase rate is high.

(About specific examples of zinc-based electroplating layers)

Subsequently, a specific example of the zinc-based electroplating layer 13 according to the present embodiment formed by the method described above will be briefly described with reference to FIGS. 2A and 2B. 2A is an example of an image when the surface of a zinc-based electroplating layer of the zinc-based electroplated steel sheet according to the present embodiment is observed with an SEM. In addition, FIG. 2B is an image photographed with a normal camera so that the surface of the zinc-based electroplating layer 13 shown in FIG. 2A can be seen as seen with the eye.

When the zinc-based electroplating layer 13 is formed by the manufacturing method described above, for example, the zinc-based electroplating layer 13 having a surface shape as shown in FIG. 2A can be formed. In the micrograph shown in Fig. 2A, the height direction of the photograph corresponds to the hairline direction, and the width direction of the photograph corresponds to the hairline orthogonal direction. As revealed from the micrograph of Fig. 2A, in the zinc-based electroplating layer 13 according to the present embodiment, it cannot be said that the smoothing portions 103 are continuously connected and distributed along the hairline direction. 101).

However, when a macroscopic observation of the zinc-based electroplated steel sheet 1 having the zinc-based electroplating layer 13 as shown in FIG. 2A, there are countless hairlines along the hairline direction as shown in FIG. 2B. It is perceived as being doing. This phenomenon is due to the fact that the grandfathers 101 are distributed at a predetermined ratio as described above.

Example

Hereinafter, the effect of the present invention will be described in detail by way of invention examples. In addition, the content of the present invention is not limited by the content described in the examples shown below.

As a base material, annealing and temper rolling completed steel sheet having a thickness of 0.6 mm (as a component composition, C: 0.05%, Si: 0.001%, Mn: 0.15%, P: 0.01%, S: 0.01%, sol. Al: An Al-killed steel sheet containing 0.04% each, and the balance containing Fe and impurities) was used. The above-described steel sheet was electrolytically degreased and washed with water using a treatment liquid of Na ₄ SiO _{4 having a} concentration of 30 g/L under the conditions of a treatment liquid of 60°C, a current density of 20 A/dm 2, and a treatment time of 10 seconds. Subsequently, the electrolytically degreased steel sheet was immersed in an aqueous H ₂ SO ₄ solution having a concentration of 50 g/L at 60° C. for 10 seconds and further washed with water to perform plating pretreatment. In addition, the surface roughness Ra (arithmetic mean roughness) of the steel plate was as shown in the table, respectively. In addition, a commercially available SUS304 steel sheet (B4 bright finished steel sheet) with a hairline of #180 was used as a comparative material (indicated as "No. SUS"). No. In SUS, a zinc-based electroplating layer was not formed and no hairline was provided. Also No. In SUS, no organic resin coating layer was also formed.

Next, the steel sheet was plated as shown in the table to form a zinc-based electroplating layer.

As the zinc-based electroplating layer, a Zn plated film, a Zn-Ni plated film, a Zn-Fe plated film, a Zn-Co plated film, a Zn-Ni-Fe plated film, and a Zn-Co-Mo plated film were used. The formation conditions of each plated film are as follows.

<Zn plating film (No. 1 to 15, 62, 66)>

The Zn plating film was plated using a plating bath of pH 2.0 containing 1.0 M of Zn sulfate heptahydrate and 50 g/L of anhydrous sodium sulfate at a bath temperature of 50° C. and a current density of 50 A/dm 2, so that the adhesion amount became the value shown in the table. Was formed by adjusting.

<Zn-Ni plating film (No. 16 to 29, 63, 67)>

When plating at a bath temperature of 50°C and a current density of 50 A/dm 2, the mixing ratio of Zn sulfate heptahydrate and Ni sulfate hexahydrate was adjusted so that the composition described in the column of “plating type” in the table might be obtained. Using a plating bath of pH 2.0 containing Zn sulfate heptahydrate and Ni sulfate hexahydrate (1.2M in total) adjusted to the mixing ratio described above, and 50 g/L of anhydrous sodium sulfate, plating so that the adhesion amount becomes the value shown in the table. It was formed by adjusting the time.

<Zn-Fe plating film (No. 30 to 43, 64, 68)>

When plating at a bath temperature of 50°C and a current density of 50 A/dm 2, the mixing ratio of Zn sulfate heptahydrate and Fe(II) sulfate heptahydrate was adjusted so that the composition described in the column of “plating type” in the table might be obtained. Using a plating bath of pH 2.0 containing Zn sulfate heptahydrate and Fe(II) sulfate heptahydrate (1.2M in total) adjusted to the mixing ratio described above, and anhydrous sodium sulfate 50g/L, the adhesion amount is the value shown in the table. It formed by adjusting the plating time so that it might become.

<Zn-Co plating film (No. 44 to 57, 65, 69)>

When plating at a bath temperature of 50°C and a current density of 50 A/dm 2, the mixing ratio of Zn sulfate heptahydrate and Co sulfate heptahydrate was adjusted so that the composition described in the column of “plating type” in the table might be obtained. Using a plating bath of pH 2.0 containing Zn sulfate heptahydrate and Co sulfate heptahydrate (1.2M in total) adjusted to the above-described mixing ratio, and 50 g/L of anhydrous sodium sulfate, plating so that the adhesion amount becomes the value shown in the table. It was formed by adjusting the time.

<Zn-Ni-Fe plating film (No. 58 to 59)>

When plating with a bath temperature of 50°C and a current density of 50 A/dm 2, the mixing ratio of Zn sulfate heptahydrate, Ni sulfate hexahydrate and Fe(II) sulfate heptahydrate was adjusted so that the composition described in the column of "plating type" in the table was obtained. . Using a plating bath having a pH of 2.0 containing Zn sulfate heptahydrate, Ni sulfate hexahydrate and Fe(II) sulfate heptahydrate (1.2M in total) adjusted to the above-described mixing ratio, and 50 g/L of anhydrous sodium sulfate, the amount of adhesion It formed by adjusting the plating time so that it might become the value shown in this table.

<Zn-Co-Mo plating film (No. 60 to 61)>

When plating with a bath temperature of 50°C and a current density of 50 A/dm 2, the mixing ratio of Zn sulfate heptahydrate, Co sulfate heptahydrate and sodium molybdate dihydrate was adjusted so that the composition described in the column of "plating type" in the table might be obtained. A plating bath of pH 4.0 containing Zn sulfate heptahydrate, Co sulfate heptahydrate, sodium molybdate dihydrate (1.2M in total), sodium formate 25g/L, and boric acid 50g/L adjusted to the above-described mixing ratio Then, the plating time was adjusted so that the adhesion amount became the value shown in the table, and formed.

During all of the above plating treatments, the plating solution was flowed so that the relative flow rate was 1 m/sec.

<Measurement of the composition of the plating film>

The composition of the obtained plating film was confirmed by immersing the plated steel sheet in 10% by mass hydrochloric acid containing an inhibitor (No. 700AS manufactured by Asahi Chemical) to dissolve and peel, and analyze the dissolved solution by ICP.

All of the above reagents used general reagents.

<Formation of hairline>

With respect to the obtained plated steel sheet, a hairline was provided along the L direction (rolling direction) of the steel sheet. The hairline was formed by pressing the abrasive paper against the steel plate. A hairline was formed so as to achieve the polishing/grinding rate indicated in the table by adjusting the particle size, rolling force and number of polishing of the polishing paper.

In addition, the polishing/grinding rate was determined by applying a hairline to one of two locations with a width of 100 mm adjacent in the width direction of the steel sheet, and not applying a hairline to the other, and calculating the amount of plating deposited before applying the hairline. It was calculated from the difference in the amount of adhesion after applying the other hairline. In addition, 7.1 was used as the value of the plating specific gravity at this time.

The plating roughness and plating amount after hairline application are as shown in the table.

<Measurement of surface roughness Ra>

The surface roughness Ra of the steel sheet after removing the plating layer was measured with a three-dimensional surface roughness measuring instrument (Surcom 1500DX3 manufactured by Tokyo Seimitsu), and the three-dimensional surface roughness Sa of the plated steel sheet was 1 nm or more in display resolution in the height direction. Moreover, it measured according to the said method using the laser microscope/VK-9710 manufactured by Keyence Corporation whose display resolution in the width direction is 1 nm or more.

<Measurement of adhesion amount of plating layer before hairline application>

The amount of plating deposited before hairline application was calculated from the difference in weight before and after dissolution and peeling by immersing the steel sheet after the plating layer was formed in 10% by mass hydrochloric acid containing an inhibitor (No. 700AS manufactured by Asahi Chemical).

<Measurement of micro-grandfather Sa _A and micro-smooth part Sa _B >

The microscopic grandfather Sa _A in each table was calculated as follows. First, using a laser microscope used to measure the three-dimensional surface roughness Sa, the roughness profile having a length of 1000 μm in the hairline direction was measured. Sa (1 µm) in a region of 1 µm x 1 µm was measured for the 10 convex part apex at the highest position among the convex part apex in the profile. Among them, the minimum value (that is, the value of Sa (1 µm) h) is described as Sa _A in the table.

The microscopic smoothing part Sa _B in each table was calculated as follows. First, a height profile of 1000 μm in length in the hairline direction was measured using a laser microscope used to measure Sa. For the 10 concave vertices at the lowest position among concave vertices in the profile, Sa (1 μm) in an area of 1 μm×1 μm around the concave vertex was measured. The maximum value among them (that is, the value of Sa (1 µm) s) was described as Sa _B in the table.

<Measurement of R50>

The three-dimensional average surface roughness Sa (50 µm) in a region of 50 µm x 50 µm was measured in succession at 21 locations in the hairline direction and 21 locations in the hairline orthogonal direction. The ratio R50 of the three-dimensional average surface roughness Sa (50 µm) in the adjacent region was calculated in a total of 20 adjacent regions. The ratio of the number occupied by adjacent regions A having an R50 of less than 0.667 or 1.500 or more among 20 adjacent regions in total is shown in each table.

<Measurement of adhesion amount of plating layer after hairline application>

The measurement of the adhesion amount of the plating layer after hairline application was performed in the same manner as the measurement of the adhesion amount of the plating layer before hairline application.

Here, the difference in the adhesion amount of the plating layer before and after the hairline is applied corresponds to the reduction in the plating layer in the process of applying the hairline.

<Measurement of the exposure rate of the subway>

The plated steel sheet obtained by the above-described manufacturing method was cut out, and images were analyzed in EPMA (JXA8230 manufactured by Nippon Denshi Corporation) for five rectangular fields of view of 1 mm on one side. The region where Zn was not detected by image analysis and Fe was detected was considered to be exposed, and the area ratio of the region was taken as the base iron exposure rate. EPMA analysis was performed under the conditions of an acceleration voltage of 15 kV and an irradiation current of 30 mA. When the detection intensity of Zn is 1/16 or less when the standard sample (pure Zn) is measured, it is determined that Zn is not detected, and the detection intensity of Fe is when the standard sample (pure Fe) is measured. It was determined that Fe was detected in the region exceeding 14/16.

These obtained results are shown in the table.

<Formation of organic resin coating layer>

A transparent organic resin coating layer was formed on the plated steel sheet provided with a hairline. As a treatment liquid for forming an organic resin, a treatment liquid of various concentrations and viscosities in which a urethane-based resin (manufactured by ADEKA, HUX-232) was dispersed in water was used. The treatment liquid was rolled up and transferred to a plated steel sheet to a thickness shown in the table after baking drying. The plated steel sheet to which the treatment liquid was transferred was placed in a furnace maintained at 250° C., held for 1 to 5 minutes until the temperature reached 210° C., and then taken out and cooled. Also No. For 62 to 69, carbon black (manufactured by Mitsubishi Chemical: #850) and cyanine blue (manufactured by Dainichi Seika Kogyo: AF Blue E-2B) were added as colorants to the organic resin film layer.

<Adjustment of treatment liquid for organic resin formation>

BYK-425 (manufactured by Big Chemie) was added as a viscosity modifier to the organic resin forming treatment liquid, and at a shear rate of 0.1 [1/sec], it has a viscosity of 10 [Pa·s] or more, and at a shear rate of 1000 [1/sec] It adjusted to have a shear viscosity of 0.01 [Pa·s] or less. Further, the viscosity modifier was not added only to the treatment liquids corresponding to the conditions 6, 9, 25, 39, and 53, and the viscosity at a shear rate of 0.1 [1/sec] was adjusted to be less than 10 [Pa·s].

<Measurement of the surface roughness Ra (CC) of the organic resin coating layer>

The surface roughness Ra (CC) of the organic resin coating layer was measured with a three-dimensional surface roughness measuring instrument (Surcom 1500DX3 manufactured by Tokyo Seimitsu) similarly to the measurement of the surface roughness Ra of the steel sheet after removing the plating layer.

<Measurement of glossiness>

The 60° glossiness G60 of the plated steel sheet after formation of the organic resin coating layer is measured in the L direction (the rolling direction of the steel sheet) and the C direction (the direction perpendicular to the rolling direction) by a gloss meter (manufactured by Suga Shikenki: Gloss Meter UGV-6P). It was measured in each of. The value of G60 obtained is shown in the table.

When the glossiness G60 (Gl) measured in the hairline direction (in the used sample, the hairline is formed along the L direction, the same direction as the L direction) was judged that the appropriate glossiness was obtained. .

<Evaluation of translucency>

The transmittance of the zinc-based electroplated steel sheet after formation of the organic resin coating layer was evaluated by the following method.

The zinc-based electroplated steel sheet after the formation of the organic resin coating layer was exposed to light from a fluorescent lamp from an angle of 45° and observed from a distance of 15 cm at an angle of 10° from the vertical direction with respect to the steel sheet, and the transmittance was evaluated according to the following evaluation criteria. What was evaluated by A or B was taken as pass. The obtained results are shown in the table.

(Evaluation standard)

A: Hairline of 20 mm or more in length can be clearly recognized

B: It is possible to visually recognize a hairline with a length of 20 mm or more with an unclear outline.

C: Cannot visually recognize a hairline of 20 mm or more

D: Hairline cannot be recognized at all

<Evaluation of film adhesion>

The film adhesion of the zinc-based electroplated steel sheet after formation of the organic resin coating layer was evaluated by the following method.

A test piece having a width of 50 mm x a length of 50 mm was prepared from the zinc-based electroplated steel sheet after the formation of the organic resin coating layer. The obtained test piece was subjected to a 180° bending process, and then a tape peeling test was performed on the outside of the bent portion. The appearance of the tape peeling portion was observed with a magnifying glass having a magnification of 10 times and evaluated according to the following evaluation criteria. The bending process was performed in an atmosphere of 20°C with a 0.5 mm spacer sandwiched therebetween. What was evaluated by A or B was taken as pass. The obtained results are shown in the table.

Also No. In SUS, since the organic resin coating layer was not formed, the film adhesion was not evaluated. Because of that, No. The evaluation result of the coating adhesion of SUS is indicated by "-".

(Evaluation standard)

A: No peeling of the organic resin coating layer and/or the zinc-based electroplating layer was observed on the adhesive side of the tape.

B: Peeling of the organic resin coating layer and/or the zinc-based electroplating layer was observed on a small portion of the adhesive surface of the tape (peel area ≤ 2%)

C: Peeling of the organic resin coating layer and/or the zinc-based electroplating layer was observed on a part of the adhesive surface of the tape (2% <peeling area ≤ 20%)

D: Peeling of the organic resin coating layer and/or the zinc-based electroplating layer was observed on the adhesive side of the tape (peeling area> 20%)

<Evaluation of corrosion resistance>

When evaluating the corrosion resistance (more specifically, long-term corrosion resistance) of the zinc-based electroplated steel sheet after formation of the organic resin coating layer, the obtained sample was first cut into a size of 75 mm×100 mm, and the end face and the back side were protected with a tape seal. Samples in which the one side and the back side were protected with a tape seal were subjected to a salt spray test of 35° C.-5% NaCl (JIS Z 2371:2015). A sample having a rust incidence of 5% or less after 240 hours was taken as OK, and a sample exceeding 5% was taken as NG. The obtained results are shown in the table.

<Evaluation of metallic feeling>

The metallic feel of the zinc-based electroplated steel sheet after formation of the organic resin coating layer was evaluated by the following method.

Glossiness measured in the hairline direction G60 (Gl) and the value of G60 (Gc) measured in the hairline orthogonal direction, and the CIE standard light source D65 condition using a spectrophotometer (manufactured by Konica Minolta: CM-2600d). Using the values of a ^* and b ^* measured by the SCE (Specula Component Excluded: specular reflection light removal) method for the color tone by L ^* a ^* b ^* color system, metallic feeling was evaluated according to the following evaluation criteria. What was evaluated by A or B was taken as pass. The obtained results are shown in the table.

(Evaluation standard)

A: 0.3≤Gc/Gl≤0.75 and (a ^*2 +b ^*2 ) ^0.5 ≤5

B: 0.3≤Gc/Gl≤0.85 or 5<(a ^*2 +b ^*2 ) ^0.5 ≤10, or 0.75<Gc/Gl≤0.85 or (a ^*2 +b ^*2 ) ^0.5 ≤10

C: 0.3>Gc/Gl, or Gc/Gl>0.85, or 10<(a ^*2 +b ^*2 ) ^0.5

As revealed from Tables 1 to 6, it can be seen that the zinc-based electroplated steel sheet corresponding to the example of the present invention has excellent light transmittance, moderate glossiness, and excellent metallic feel and film adhesion. On the other hand, the zinc-based electroplated steel sheet corresponding to the comparative example of the present invention was not able to obtain excellent results with respect to at least any of the items of light transmittance, glossiness, metallic feel, and film adhesion.

Hereinafter, preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to these examples. It is clear that a person having ordinary knowledge in the field of the technology to which the present invention belongs can conceive various changes or modifications within the scope of the technical idea described in the claims. It is understood to be within the technical scope of the invention.

1: zinc-based electroplated steel sheet
11: grater
13: Zinc-based electroplating layer
15: organic resin coating layer
101a, 101b: grandfather
103: smoothing part

Claims (9)

Grater;
A zinc-based electroplating layer disposed on at least one surface of the steel sheet and having a hairline stretched on the surface in a predetermined direction;
Equipped,
The zinc-based electroplating layer,
A microscopic roughness whose three-dimensional average surface roughness Sa (1 µm)h defined in the following (A) is more than 200 nm and not more than 2000 nm;
A microscopic smoothing portion in which the three-dimensional average surface roughness Sa (1 µm)s defined in the following (B) is more than 5 nm and not more than 200 nm;
Have,
In the zinc-based electroplating layer, a three-dimensional average surface roughness Sa of a region of 50 µm x 50 µm along each of a hairline direction in which the hairline is stretched and a hairline orthogonal direction perpendicular to the hairline direction (50㎛) is continuously measured to calculate R50, which is the ratio of Sa (50㎛) in the adjacent region formed by the two neighboring regions, and the adjacent region with the R50 less than 0.667 or 1.500 or more is adjacent In the case of region A, the ratio of the number of adjacent regions A in any of the hairline direction and the hairline orthogonal direction is 30% or more.
Zinc-based electroplated steel sheet, characterized in that.
(A) Sa (1 µm) h is a measurement of a roughness profile of 1000 µm in the hairline direction, and at the top of the convex part at 10 points at the highest position among the apex of the convex part in the roughness profile. On the other hand, the three-dimensional average surface roughness Sa (1 µm) of a region of 1 µm × 1 µm was measured around the vertices of each of the convex portions, and the minimum value of the measured three-dimensional average surface roughness Sa (1 µm) was indicated. .
(B) Sa (1 µm) s is a measurement of a roughness profile of 1000 µm in the direction of the hairline, and the 10 points of the concave apex at the lowest position among the concave vertexes in the roughness profile On the other hand, the three-dimensional average surface roughness Sa (1 μm) of a region of 1 μm×1 μm around each of the concave apex was measured, and the maximum value of the measured three-dimensional average surface roughness Sa (1 μm) was shown. . The method of claim 1,
As an upper layer of the zinc-based electroplating layer, further comprising an organic resin coating layer having a light transmission property and a thickness of 10 μm or less.
Zinc-based electroplated steel sheet, characterized in that. The method of claim 2,
The organic resin coating layer contains a colorant,
When the hue of the organic resin coating layer by the L ^* a ^* b ^* color system is measured by the specular light removal method using a color difference meter using a CIE standard light source D65, (a ^*2 +b ^*2 ) ^0.5 indicating saturation Is less than or equal to 10
Zinc-based electroplated steel sheet, characterized in that. The method according to claim 2 or 3,
In the state where the organic resin coating layer is present, the surface roughness Ra (CC) measured along the hairline orthogonal direction, and the hairline measured along the hairline orthogonal direction after peeling the organic resin coating layer. The surface roughness Ra (MC) of the linked electroplating layer satisfies the relationship shown in the following equation (1).
Zinc-based electroplated steel sheet, characterized in that.
Ra(CC)<Ra(MC)<5×Ra(CC)… Equation (1) The method according to any one of claims 1 to 4,
The base iron exposure rate of the zinc-based electroplating layer is less than 5%
Zinc-based electroplated steel sheet, characterized in that. The method according to any one of claims 1 to 5,
The adhesion amount of the zinc-based electroplating layer is 10g/m2 to 60g/m2
Zinc-based electroplated steel sheet, characterized in that. The method according to any one of claims 1 to 6,
The surface roughness Ra of the steel sheet after removing both the zinc-based electroplating layer or the organic resin coating layer and the zinc-based electroplating layer provided as an upper layer of the zinc-based electroplating layer is 1.0 μm or more and 1.7 μm or less.
Zinc-based electroplated steel sheet, characterized in that. The method according to any one of claims 1 to 7,
The zinc-based electroplating layer contains 5% by mass to 20% by mass in total of any one or more elements selected from the group consisting of Fe, Ni, and Co.
Zinc-based electroplated steel sheet, characterized in that. The method according to any one of claims 1 to 8,
The surface roughness Ra of the steel sheet after removing both of the zinc-based electroplating layer or the organic resin coating layer and the zinc-based electroplating layer provided as an upper layer of the zinc-based electroplating layer is 60% or less of the thickness of the zinc-based electroplating layer.
Zinc-based electroplated steel sheet, characterized in that.

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