Hot-dip plated steel sheet

Abstract

In a pattern portion and a non-pattern portion of a hot-dip plating layer of the hot-dip plated steel sheet, the relationship between reflected light toward the pattern portion and the non-pattern portion in the normal direction of incident light having an incident angle in the range of 0 DEG or more and less than 90 DEG with respect to the normal direction of the surface of the steel sheet satisfies expressions (1) and (2). IPH-IBH / IPM-IBM < 1.0 (1) IPL-IBL / IPM-IBM < 1.0 (2) IPH, IBH being the reflection intensity of the pattern portion and the non-pattern portion with respect to incident light having an incident angle of 0 DEG or more and less than 35 DEG. The IPM and the IBM are the reflection intensities of the pattern portion and the non-pattern portion in the normal direction with respect to incident light having an incident angle of 35-80 DEG. IPL and IBL are reflection intensities of the pattern portion and the non-pattern portion in the normal direction with respect to incident light having an incident angle of more than 80 DEG and less than 90 DEG.

Description

Technical Field

[0001] The present invention relates to a hot-dip plated steel sheet. This application claims priority based on Japanese Patent Application No. 2022-094349 filed on June 10, 2022, the contents of which are incorporated herein by reference. Background Art

[0002] Compared with hot-dip galvanized steel sheets, Zn-Al-Mg hot-dip galvanized steel sheets have higher corrosion resistance and are widely used in various manufacturing industries such as building materials, home appliances, and automobiles. In recent years, their usage has been gradually increasing.

[0003] However, in order to express characters, patterns, designs, etc. on the surface of the hot-dip coating layer of the hot-dip coated steel sheet, the hot-dip coating layer may be subjected to a printing or painting process to express characters, patterns, designs, etc. on the surface of the hot-dip coating layer.

[0004] However, if the hot-dip coating is subjected to a process such as printing or painting, there is a problem of increased cost and time for drawing text and designs. In addition, when text and designs are printed or painted on the surface of the coating, there is a concern that not only the metallic glossy appearance that is popular with users is lost, but also the durability is reduced due to the degradation of the coating itself and the degradation of the adhesion (or adhesion) of the coating over time, and the text and designs disappear over time.

[0005] Therefore, as shown in Patent Document 1 listed below, a technique for expressing characters, designs, etc. on the surface of the coating layer of a Zn—Al—Mg hot-dip coated steel sheet has been proposed.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 6648871 Summary of the invention

[0009] Problems to be solved by the invention

[0010] The Zn-Al-Mg hot-dip plated steel sheet described in Patent Document 1 is a steel sheet that can form straight lines, curved lines, figures, numbers, symbols, characters, or intentional patterns formed by combining these on the surface of the plated layer without ink coating or grinding. Thus, for example, the manufacturer's name, manufacturing number, emblem formed by combining characters and glyphs, etc. can be shown on the surface of the plated layer, which has the advantage of facilitating the management of the steel sheet.

[0011] However, from the perspective of users, these intentional patterns are useful, but in parts, products, or structural parts using patterned hot-dip galvanized steel sheets as raw materials, there is a requirement that the patterns be easily recognizable in human vision when light is incident from a specific direction, but difficult to recognize when light is incident from other directions.

[0012] The present invention is completed in view of the above situation, and its subject is to provide a hot-dip coated steel plate, which can easily identify patterns such as text and design revealed on the coating surface in human vision when light is incident from a specific direction, but makes it difficult to identify the pattern when light is incident from other directions.

[0013] Means for solving problems

[0014] In order to solve the above-mentioned problems, the present invention adopts the following configuration.

[0015] [1] A hot-dip plated steel sheet comprising a steel sheet and a hot-dip plated layer formed on a surface of the steel sheet, wherein:

[0016] The hot-dip coating layer contains, as an average composition, 4 to 22 mass % of Al, 1.0 to 10 mass % of Mg, and the remainder contains Zn and impurities.

[0017] The hot-dip plated layer has a pattern portion and a non-pattern portion,

[0018] For incident light having an incident angle in the range of 0° or more and less than 90° relative to the normal direction of the surface of the steel plate, the relationship between the reflected light of the pattern portion in the normal direction and the reflected light of the non-pattern portion in the normal direction satisfies the following equations (1) and (2):

[0019] |I PH -I BH | / |I PM -I BM |<1.0 (1)

[0020] |I PL -I BL | / |I PM -I BM |<1.0 (2)

[0021] In the formula,

[0022] I PH : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°,

[0023] I BH : Reflection intensity of the non-pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°,

[0024] I PM : Reflection intensity of the pattern portion in the normal direction for incident light at an incident angle of 35° to 80°,

[0025] I BM : Reflection intensity of the non-pattern part in the normal direction for incident light with an incident angle of 35° to 80°,

[0026] I PL : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle exceeding 80° and less than 90°,

[0027] I BL : Reflection intensity of the non-pattern portion for incident light with an incident angle of more than 80° and less than 90° in the normal direction.

[0028] [2] A hot-dip plated steel sheet comprising a steel sheet and a hot-dip plated layer formed on a surface of the steel sheet, wherein:

[0029] The hot-dip coating layer contains, as an average composition, 4 to 22 mass % of Al, 1.0 to 10 mass % of Mg, and the remainder contains Zn and impurities.

[0030] further comprising one or two selected from the following Group A and Group B,

[0031] The hot-dip plated layer has a pattern portion and a non-pattern portion,

[0032] For incident light having an incident angle in the range of 0° or more and less than 90° relative to the normal direction of the surface of the steel plate, the relationship between the reflected light of the pattern portion in the normal direction and the reflected light of the non-pattern portion in the normal direction satisfies the following equations (1) and (2):

[0033] |I PH -I BH | / |I PM -I BM |<1.0 (1)

[0034] |I PL -I BL | / |I PM -I BM |<1.0 (2)

[0035] [Group A] Si: 0.0001 to 2 mass%

[0036] [Group B] Any one or more of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, and C: 0.0001 to 2% by mass in total

[0037] In the formula,

[0038] I PH : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°,

[0039] I BH : Reflection intensity of the non-pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°,

[0040] I PM : Reflection intensity of the pattern portion in the normal direction for incident light at an incident angle of 35° to 80°,

[0041] I BM : Reflection intensity of the non-pattern part in the normal direction for incident light with an incident angle of 35° to 80°,

[0042] I PL : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle exceeding 80° and less than 90°,

[0043] I BL : Reflection intensity of the non-pattern portion for incident light with an incident angle of more than 80° and less than 90° in the normal direction.

[0044] [3] The hot-dip plated steel sheet according to [1] or [2] above, characterized in that the pattern portion is arranged in a shape that becomes any one of a straight line portion, a curved line portion, a dot portion, a figure, a number, a symbol or a character, or a shape formed by a combination of two or more of them.

[0045] [4] The hot-dip coated steel sheet according to [1] or [2] above, wherein the coating weight of the hot-dip coating layer is 30 to 600 g / m2 on both sides of the steel sheet. 2 .

[0046] [5] The hot-dip coated steel sheet according to [3] above, wherein the coating weight of the hot-dip coating layer is 30 to 600 g / m2 on both sides of the steel sheet. 2 .

[0047] [6] The hot-dip plated steel sheet according to [2] above, wherein the hot-dip plated layer has an average composition containing the group A in mass %.

[0048] [7] The hot-dip plated steel sheet according to [2] above, wherein the hot-dip plated layer has an average composition containing the B group in mass %.

[0049] [8] The hot-dip plated steel sheet according to [1] or [2], wherein the proportion of the inclined surface having an inclination angle of 17° to 40° in the pattern portion is 60% or more.

[0050] Effects of the Invention

[0051] According to the present invention, when light is incident from a specific direction, patterns such as letters and designs revealed on the surface of the plated layer can be easily recognized by human vision, while when light is incident from other directions, the patterns can be difficult to recognize. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram for explaining the intensity of reflected light at each incident angle in the pattern portion and the non-pattern portion.

[0053] Figure 2 It is a schematic diagram showing the intensity of reflected light at each incident angle in the pattern portion and the non-pattern portion of the hot-dip plated steel sheet according to the embodiment of the present invention. DETAILED DESCRIPTION

[0054] A hot-dip plated steel sheet according to an embodiment of the present invention will be described.

[0055] The hot-dip plated steel sheet of the present embodiment comprises a steel sheet and a hot-dip plated layer formed on the surface of the steel sheet, wherein the hot-dip plated layer contains, in terms of average composition, 4 to 22% Al and 1.0 to 10% Mg, with the remainder comprising Zn and impurities, and the hot-dip plated layer forms a pattern portion and a non-pattern portion in a top view, and for incident light having an incident angle in the range of greater than 0° and less than 90° relative to the normal direction of the steel sheet surface, the relationship between the reflected light of the pattern portion in the normal direction and the reflected light of the non-pattern portion in the normal direction satisfies the following equations (1) and (2).

[0056] |I PH -I BH | / |I PM -I BM |<1.0 (1)

[0057] |I PL -I BL | / |I PM -I BM |<1.0 (2)

[0058] Among them, I PH ,I BH ,I PM ,I BM ,IPL ,I BL As described below.

[0059] I PH : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°.

[0060] I BH : Reflection intensity of the non-pattern portion for incident light with an incident angle of 0° or more and less than 35° in the normal direction.

[0061] I PM : Reflection intensity of the pattern portion in the normal direction for incident light at an incident angle of 35° to 80°.

[0062] I BM : Reflection intensity of the non-pattern portion for incident light at an incident angle of 35° to 80° in the normal direction.

[0063] I PL : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle exceeding 80° and less than 90°.

[0064] I BL : Reflection intensity of the non-pattern portion for incident light with an incident angle of more than 80° and less than 90° in the normal direction.

[0065] The material of the steel plate that serves as the base of the hot-dip coating is not particularly limited. Details will be described later, but as the material, ordinary steel and the like can be used without particular limitation, aluminum-killed steel and some high-alloy steel can also be used, and the shape is not particularly limited. The hot-dip coating layer according to the present embodiment can be formed by applying the hot-dip coating method described later to the steel plate.

[0066] Next, the chemical composition of the hot-dip coating will be described.

[0067] The hot-dip coating layer contains Al: 4 to 22 mass %, Mg: 1.0 to 10 mass %, and the remainder contains Zn and impurities as an average composition. It is more preferred that the hot-dip coating layer contains Al: 4 to 22 mass %, Mg: 1.0 to 10 mass %, and the remainder is composed of Zn and impurities as an average composition. In addition, the hot-dip coating layer may contain Si: 0.0001 to 2 mass % as an average composition.

[0068] The hot-dip coating layer may further contain one or two selected from the following Group A and Group B.

[0069] [Group A] Si: 0.0001 to 2 mass%

[0070] [Group B] Any one or more of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, and C: 0.0001 to 2% by mass in total

[0071] The Al content is in the range of 4 to 22 mass % based on the average composition. Al is preferably contained to ensure corrosion resistance. If the Al content in the hot-dip coating is 4 mass % or more, the effect of improving corrosion resistance is higher. If it exceeds 22 mass %, not only is the effect of improving corrosion resistance saturated, but there is also a risk of reduction. From the viewpoint of corrosion resistance, the lower limit of the Al content is preferably 6 mass %, and more preferably 11 mass %. The upper limit of the Al content is preferably set to 19 mass %.

[0072] The Mg content is in the range of 1.0 to 10% by mass based on the average composition. Mg is preferably contained to improve corrosion resistance. If the Mg content in the hot-dip coating is 1.0% by mass or more, the effect of improving corrosion resistance is higher. However, if Mg exceeds 10% by mass, the generation of dross in the coating bath becomes significant, and it becomes difficult to stably manufacture hot-dip coated steel sheets, so the Mg content is set to 10% by mass or less. From the viewpoint of the balance between corrosion resistance and dross generation, the lower limit of the Mg content is preferably 1.5% by mass, and more preferably 2.0% by mass. The upper limit of the Mg content is preferably 8.0% by mass, and more preferably 6.0% by mass.

[0073] The hot-dip coating may also contain 0.0001 to 2.0% Si by mass in terms of average composition. Si is an effective element for improving the adhesion of the hot-dip coating. Since the effect of improving adhesion is shown by containing 0.0001% Si or more in the hot-dip coating, it is preferred to contain 0.0001% Si or more. On the other hand, even if more than 2% Si is contained, the effect of improving the adhesion of the coating is saturated, so even if Si is contained in the hot-dip coating, the Si content is set to less than 2% by mass. From the viewpoint of coating adhesion, the lower limit of the Si content in the hot-dip coating may be set to 0.0010% by mass, or 0.0100% by mass. From the viewpoint of coating adhesion, the upper limit of the Si content in the hot-dip coating may be set to 1% by mass, or 0.8% by mass.

[0074] The hot-dip coating layer may contain 0.0001 to 2 mass % of one or more of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, and C in total in an average composition. By containing these elements, the corrosion resistance of the hot-dip coating layer can be further improved. REM is one or more of the rare earth elements having atomic numbers of 57 to 71 in the periodic table.

[0075] The remainder of the chemical composition of the hot-dip coating is zinc and impurities. The impurities include impurities inevitably contained in the base metal other than zinc, and impurities contained in the coating bath due to the melting of steel.

[0076] Furthermore, the average composition of the hot-dip coating can be measured by the following method. First, after removing the surface coating with a coating stripper that does not corrode the coating (e.g., NEOREVER SP-751 manufactured by Sancai Chemical Co., Ltd.), the hot-dip coating is dissolved with hydrochloric acid to which a corrosion inhibitor (e.g., HIBIRON manufactured by Sugimura Chemical Industry Co., Ltd.) is added, and the composition can be determined by performing inductively coupled plasma (ICP) emission spectroscopy analysis on the resulting solution. In addition, when there is no surface coating, the removal of the surface coating can be omitted.

[0077] Next, the structure of the hot-dip coating will be described. The structure of the hot-dip coating of the present embodiment may also have the structure described below, for example. As a result, the appearance of the surface of the hot-dip coating becomes a satin appearance, which is a surface with excellent aesthetics. Furthermore, the structure of the hot-dip coating can be obtained as long as the coating has the above-mentioned chemical composition, so it is not necessary to limit the structure of the hot-dip coating in the present invention.

[0078] The hot-dip coating layer containing Al, Mg and Zn includes [Al phase] and [ternary eutectic structure of Al / Zn / MgZn2]. Specifically, in the base of [ternary eutectic structure of Al / Zn / MgZn2], there is a morphology including [Al phase]. In addition, in the base of [ternary eutectic structure of Al / Zn / MgZn2], [MgZn2 phase] and [Zn phase] may also be included. In addition, in the case of containing Si, [Mg2Si phase] may also be included in the base of [ternary eutectic structure of Al / Zn / MgZn2].

[0079] [Ternary eutectic structure of Al / Zn / MgZn2]

[0080] The so-called [ternary eutectic structure of Al / Zn / MgZn2] is a ternary eutectic structure of Al phase, Zn phase and intermetallic compound MgZn2 phase. The Al phase forming the ternary eutectic structure is equivalent to, for example, the "Al" phase at high temperature in the ternary equilibrium phase diagram of Al-Zn-Mg (which is an Al solid solution containing Zn and a small amount of Mg).

[0081] The Al" phase at high temperature is usually separated into a fine Al phase and a fine Zn phase at room temperature. The Zn phase in the ternary eutectic structure is a Zn solid solution in which a small amount of Al and, depending on the situation, a small amount of Mg is further dissolved. The MgZn2 phase in the ternary eutectic structure is an intermetallic compound phase existing near Zn: about 84 mass % in the Zn-Mg binary system equilibrium phase diagram.

[0082] From the phase diagram alone, it can be considered that no other added elements are dissolved in each phase, or even if dissolved, they are extremely small. However, their amounts cannot be clearly distinguished in ordinary analysis, so in this specification, the ternary eutectic structure composed of these three phases is expressed as [ternary eutectic structure of Al / Zn / MgZn2].

[0083] [Al phase]

[0084] The so-called [Al phase] is a phase with clear boundaries and can be seen as an island in the base of the ternary eutectic structure, which is equivalent to the "Al" phase at high temperature in the ternary equilibrium phase diagram of Al-Zn-Mg (it is an Al solid solution in which Zn is dissolved, containing a small amount of Mg). The Al" phase at high temperature has different amounts of dissolved Zn or Mg depending on the concentration of Al or Mg in the plating bath. It can be considered that the Al" phase at high temperature is usually separated into fine Al phase and fine Zn phase at room temperature, but the island shape seen at room temperature is caused by the shape of the Al" phase at high temperature.

[0085] Judging from the phase diagram alone, it can be considered that no other added elements are dissolved in this phase, or even if dissolved, they are only in very small amounts. However, since it is not possible to clearly distinguish them in ordinary analysis, the phase derived from the Al" phase at high temperature and whose shape is derived from the shape of the Al" phase is referred to as "Al phase" in this specification.

[0086] [Al phase] can be clearly distinguished from the Al phase forming the ternary eutectic structure in microscopic observation.

[0087] [Zn phase]

[0088] The so-called [Zn phase] is a phase that has a clear boundary and can be seen as an island in the base of the ternary eutectic structure, and in fact, a small amount of Al or a small amount of Mg is sometimes dissolved. From the phase diagram alone, it can be considered that other added elements are not dissolved in this phase, or even if dissolved, they are extremely trace.

[0089] The [Zn phase] can be clearly distinguished from the Zn phase forming the ternary eutectic structure in microscopic observation. The hot-dip galvanized layer according to the present embodiment may contain the [Zn phase] depending on the manufacturing conditions, but the influence on the corrosion resistance caused by the [Zn phase] is hardly found. Therefore, even if the hot-dip galvanized layer contains the [Zn phase], there is no particular problem.

[0090] [MgZn2 phase]

[0091] The so-called [MgZn2 phase] is a phase that has a clear boundary and can be seen as an island in the base of the ternary eutectic structure, and in fact, sometimes a small amount of Al is dissolved. From the phase diagram alone, it can be considered that no other added elements are dissolved in this phase, or even if they are dissolved, they are extremely small.

[0092] The [MgZn2 phase] and the MgZn2 phase forming the ternary eutectic structure can be clearly distinguished in microscopic observation. In the hot-dip coating of the present embodiment, the [MgZn2 phase] may not be contained due to manufacturing conditions, but the [MgZn2 phase] may be contained in the hot-dip coating under most manufacturing conditions.

[0093] [Mg2Si phase]

[0094] The so-called [Mg2Si phase] is a phase that has a clear boundary and can be seen as an island in the solidified structure of the Si-added coating. From the phase diagram alone, it can be considered that there is no solid solution of Zn, Al, and other added elements in the [Mg2Si phase], or even if they are solid solution, they are extremely small. The [Mg2Si phase] can be clearly distinguished from other phases in the hot-dip coating when observed under a microscope.

[0095] The hot-dip coating of this embodiment can be formed by immersing the steel sheet in a coating bath, lifting it up, and then solidifying the molten metal attached to the surface of the steel sheet. At this time, the [Al phase] is initially formed, and then the [ternary eutectic structure of Al / Zn / MgZn2] is formed as the temperature of the molten metal decreases. Depending on the chemical composition of the hot-dip coating (i.e., the chemical composition of the coating bath), the [Mg2Si phase], [MgZn2 phase], or [Zn phase] may be formed in the base of the [ternary eutectic structure of Al / Zn / MgZn2].

[0096] Next, the pattern portion and the non-pattern portion on the hot-dip plated layer surface will be described.

[0097] A pattern portion and a non-pattern portion are formed on the surface of the hot-dip coating of the present embodiment. The pattern portion and the non-pattern portion can also be configured in a manner that becomes a prescribed shape. Preferably, the pattern portion is configured in a manner that becomes any one of a straight portion, a curved portion, a dot portion, a figure, a number, a symbol or a text, or a shape formed by a combination of two or more of them in a top view. The pattern portion showing such a shape can be said to be formed intentionally. The straight portion and the curved portion in the pattern portion preferably have a width that can be visually identified as described later, and each has a length of more than 1mm. The dot portion in the pattern portion preferably has an equivalent circle diameter of more than 1mm and less than 10mm, and more preferably a plurality of dot portions are regularly arranged. In addition, when the pattern portion is a figure, a number, a symbol or a text, it is preferred that these shapes can be visually identified as described later. By showing such a size and shape, it can be said that it is formed more intentionally. In addition, the non-pattern portion is an area outside the pattern portion. In addition, even if the shape of the pattern portion lacks a part as if the dots fall off, it is also allowed as long as it can be identified as a whole. Furthermore, the non-pattern portion may have a shape that borders the boundary of the pattern portion.

[0098] When any one of straight line portions, curved line portions, dot portions, graphics, numbers, symbols or characters, or a shape formed by a combination of two or more of them is arranged on the surface of the hot-dip galvanized layer, these areas can be used as pattern portions, and the areas other than these areas can be used as non-pattern portions. Preferably, these shapes of the pattern portions are artificially formed.

[0099] The boundary between the pattern portion and the non-pattern portion can be grasped with the naked eye. The boundary between the pattern portion and the non-pattern portion can also be grasped visually from an enlarged image using an optical microscope or a magnifying glass.

[0100] The pattern portion can be formed by visually observing with the naked eye, or by using a magnifying glass or a microscope to visually discern the existence of the pattern portion. In addition, the non-pattern portion is the area occupying most of the hot-dip coating (hot-dip coating surface), and the pattern portion is sometimes configured in the non-pattern portion.

[0101] Furthermore, from the viewpoint of improving the visual recognition of the pattern part, the area ratio of the pattern part in the hot-dip coating surface is preferably significantly smaller than that of the non-pattern part. For example, the area ratio of the pattern part in the hot-dip coating surface is preferably 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less.

[0102] The pattern portion is arranged in a prescribed shape in the non-pattern portion. Specifically, the pattern portion is arranged in the non-pattern portion in a manner that becomes any one of a straight line portion, a curved line portion, a figure, a dot portion, a figure, a number, a symbol or a character, or a shape composed of two or more of them. By intentionally adjusting the shape of the pattern portion, any one of a straight line portion, a curved line portion, a figure, a dot portion, a figure, a number, a symbol or a character, or a shape composed of two or more of them can appear on the surface of the hot-dip coating. For example, a character column, a number column, a symbol, a logo, a line diagram, a design diagram or a combination thereof formed by the pattern portion can appear on the surface of the hot-dip coating. The shape is a shape intentionally or artificially formed by the manufacturing method described later, and is not formed naturally. As long as a person skilled in the art who understands the appearance of a conventional hot-dip coating can easily distinguish between a pattern portion and a non-pattern portion having an artificial shape. In this specification, for example, the difference in appearance of the pattern portion and the non-pattern portion is not reflected in the appearance of the hot-dip coated steel sheet by the difference in the crystal structure of the metal organization and the presence or absence of tiny defects that cannot be visually seen.

[0103] If there is an intensity difference between the reflected light of the pattern part and the reflected light of the non-pattern part for the light incident on the hot-dip galvanized layer from a specific direction, the pattern part and the non-pattern part become easy to identify in human vision. On the contrary, if there is no intensity difference between the reflected light of the pattern part and the reflected light of the non-pattern part, or the intensity difference is small, the pattern part and the non-pattern part become difficult to identify in human vision. Therefore, in this embodiment, the surface morphology of the hot-dip galvanized layer is controlled to increase the intensity difference of the reflected light of the pattern part and the non-pattern part for the incident light incident from a specific direction, and reduce the intensity difference of the reflected light of the pattern part and the non-pattern part for the incident light incident from directions other than the specific direction. As a result, the pattern part can be identified only when the light is incident from a specific direction. Furthermore, the so-called specific direction is set in the range of 35° to 80° relative to the direction of the normal to the surface of the steel plate.

[0104] Specifically, in the hot-dip galvanized layer of the present embodiment, for incident light with an incident angle in the range of more than 0° and less than 90°, the relationship between the reflected light in the normal direction of the pattern portion and the reflected light in the normal direction of the non-pattern portion satisfies the relationship of the following equations (1) and (2). The incident angle of the incident light is an angle relative to the normal direction of the steel plate surface. The pattern portion and the non-pattern portion that satisfy the relationship of the following equations (1) and (2) are preferably adjacent pattern portions and non-pattern portions sandwiching the above-mentioned boundary.

[0105] |I PH -I BH | / |I PM -I BM |<1.0 (1)

[0106] |I PL -I BL | / |I PM -I BM |<1.0 (2)

[0107] I in formula (1) and formula (2) PH ,I BH ,I PM ,I BM ,I PL ,I BL They are described as follows respectively.

[0108] I PH : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°.

[0109] I BH : Reflection intensity of the non-pattern portion for incident light with an incident angle of 0° or more and less than 35° in the normal direction.

[0110] I PM : Reflection intensity of the pattern portion in the normal direction for incident light at an incident angle of 35° to 80°.

[0111] I BM : Reflection intensity of the non-pattern portion for incident light at an incident angle of 35° to 80° in the normal direction.

[0112] I PL : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle exceeding 80° and less than 90°.

[0113] I BL : Reflection intensity of the non-pattern portion for incident light with an incident angle of more than 80° and less than 90° in the normal direction.

[0114] Reference Figure 1 (A)~(D) for I PH ,I BH ,I PM ,I BM ,I PL ,I BL Explain in detail.

[0115] Figure 1 (A) is a diagram illustrating the incident angle of the incident light, showing the steel plate surface S, the normal H of the steel plate surface, the range of the incident angle greater than 0° and less than 35° relative to the normal H, the range of the incident angle from 35° to 80°, and the range of the incident angle greater than 80° and less than 90°.

[0116] Figure 1 (B)~ Figure 1(D) shows the relationship between incident light and reflected light in the pattern portion.

[0117] Figure 1 (B) shows the reflection intensity I PH . Reflection intensity I PH is the reflection intensity of the pattern portion, which is the reflection intensity in the normal direction of the incident light with an incident angle of 0° or more and less than 35°. Figure 1 (C) shows the reflection intensity I PM . Reflection intensity I PM is the reflection intensity of the pattern part, which is the reflection intensity in the normal direction of the incident light with an incident angle of 35° to 80°. Figure 1 (D) shows the reflection intensity I PL . Reflection intensity I PL It is the reflection intensity of the pattern portion, and is the reflection intensity in the normal direction to incident light having an incident angle of more than 80° and less than 90°.

[0118] Figure 1 (E)~ Figure 1 (G) shows the relationship between incident light and reflected light in the non-pattern portion.

[0119] Figure 1 (E) shows the reflection intensity I BH . Reflection intensity I BH The reflection intensity of the non-pattern portion is the reflection intensity in the normal direction to incident light having an incident angle of 0° or more and less than 35°. Figure 1 (F) shows the reflection intensity I BM . Reflection intensity I BM The reflection intensity of the non-pattern portion is the reflection intensity in the normal direction to incident light having an incident angle of 35° to 80°. Figure 1 (D) shows the reflection intensity I BL . Reflection intensity I BL The reflection intensity of the non-pattern portion is the reflection intensity in the normal direction to incident light having an incident angle of more than 80° and less than 90°.

[0120] Next, refer to Figure 2 Formula (1) and formula (2) are explained. PM -I BM |、|I PH -I BH |and|I PL -I BL |The relationship with the visual recognition of the pattern part is explained. Figure 2 , the relationship between incident light and reflected light in each of the pattern portion and the non-pattern portion, and the intensity difference (brightness difference) of reflected light in the pattern portion and the non-pattern portion are shown.

[0121] |I PM -I BM | is the reflection intensity I of the pattern part when the incident light is incident at an incident angle of 35° to 80° PM The reflection intensity I of the non-pattern part BM The greater the difference in reflection intensity between the patterned part and the non-patterned part, the greater the difference in reflection intensity between the patterned part and the non-patterned part. PM -I BM | is larger, the more significant the difference in brightness of the reflected light between the pattern part and the non-pattern part is, and thus the pattern part becomes easier to visually recognize. PM -I BM The smaller | is, the closer the brightness of the reflected light of the pattern part and the non-pattern part is, and the pattern part becomes more difficult to visually recognize. PH -I BH |、|I PL -I BL | The same is true. The following is explained by giving specific examples.

[0122] Figure 2 As an example for easily visually recognizing the pattern part, the magnitude of the reflection intensity of the pattern part and the non-pattern part when incident light with an incident angle of 0 to 90° is incident is visually shown. The length of the arrow in each figure corresponds to the magnitude relationship between the reflection intensity and the intensity difference. Figure 2 (A3), (B3), and (C3) show the intensity difference of the incident light at each incident angle. PM -I BM |with|I PH -I BH |and|I PL -I BL | is larger than that of |I. This is because when the incident light is incident at an angle of 35 to 80°, |I PM -I BM | becomes relatively large. On the other hand, when the incident light is incident at an angle other than 35° to 80°, |I PH -I BH |、|I PL -I BL | becomes relatively small, and thus, when incident light is incident at an incident angle of 35 to 80 degrees, the pattern portion becomes easily visible.

[0123] |I PM -I BM | is the difference in reflection intensity between the patterned part and the non-patterned part when the incident light is incident at an incident angle of 35° to 80°, |I PH -I BH| is the difference in reflection intensity between the patterned portion and the non-patterned portion when incident light with an incident angle of 0° or more and less than 35° is incident, |I PL -I BL | is the difference in reflection intensity between the patterned portion and the non-patterned portion when incident light with an incident angle of more than 80° and less than 90° is incident. Therefore, the condition for easily visually recognizing the patterned portion when incident light with an incident angle of 35° to 80° is |I PH -I BH | / |I PM -I BM |and|I PL -I BL | / |I PM -I BM | are all lower than 1.0, which means that the above equations (1) and (2) are satisfied.

[0124] As described above, by satisfying the above-mentioned formulas (1) and (2), when the incident light is incident at an incident angle of 35° to 80°, the pattern portion becomes easy to visually recognize, and when the incident light is incident at an incident angle of greater than 0° and less than 35° and greater than 80° and less than 90°, the pattern portion becomes difficult to visually recognize.

[0125] Furthermore, Figure 2 (A1), (A2), (B1), (B2), (C1), and (C2) are described below. Figure 2 (A1) and (A2) show the reflection intensity I of the pattern portion when incident light with an incident angle of 0° or more and less than 35° is incident. PH and the reflection intensity I of the non-patterned part BH The length of the arrow corresponds to the magnitude of the reflection intensity. In addition, Figure 2 (A3) shows the reflection intensity I of the pattern part PH and the reflection intensity I of the non-patterned part BH The strength difference is |I PH -I BH |.

[0126] also, Figure 2 (B1) and (B2) show the reflection intensity I of the pattern portion when incident light with an incident angle of 35° to 80° is incident. PM and the reflection intensity I of the non-patterned part BM The length of the arrow corresponds to the magnitude of the reflection intensity. Figure 2 (B3) shows the reflection intensity I of the pattern part. PM and the reflection intensity I of the non-patterned part BM The strength difference is |I PH -I BH |.

[0127] also, Figure 2 (C1) and (C2) show the reflection intensity I of the pattern portion when the incident light is incident at an incident angle of more than 80° and less than 90°. PL and the reflection intensity I of the non-patterned part BL The length of the arrow corresponds to the magnitude of the reflection intensity. Figure 2 (C3) shows the reflection intensity I of the pattern part PL and the reflection intensity I of the non-patterned part BL The strength difference is |I PL -I BL |.

[0128] As described above, the hot-dip plated steel sheet of the present embodiment satisfies both equations (1) and (2), and when incident light at an incident angle of 35° to 80° is incident, the pattern portion becomes easy to visually recognize from the direction of the normal line H, whereas when incident light at an incident angle other than 35° to 80° is incident, the pattern portion becomes difficult to visually recognize from the direction of the normal line H. Thus, when light is incident on the hot-dip plated layer from a direction of 35° to 80°, the pattern portion can be recognized visually by a person, but when light is incident from a direction other than that, the pattern portion can be made difficult to recognize.

[0129] The combination of the reflected light intensities of the pattern portion and the non-pattern portion in the hot-dip galvanized layer of the present embodiment may satisfy both equations (1) and (2) and is not limited to Figure 2 The relationship shown.

[0130] The hot-dip plated steel sheet according to the present embodiment may also have a chemical conversion coating layer or a coating layer on the hot-dip plated surface. The type of the chemical conversion coating layer or the coating layer is not particularly limited, and a known chemical conversion coating layer or coating layer may be used.

[0131] As an example of a chemical conversion coating, a chemical conversion coating containing a phthalocyanine pigment coated with at least one of a resin and a surfactant can be exemplified. A hot-dip coating provided with such a chemical conversion coating can be colored with a phthalocyanine pigment to impart a preferred decorative appearance to the coating surface, and further improve the visual recognition of the pattern portion. In addition, the corrosion resistance and weather resistance of the chemical conversion coating can also be improved.

[0132] In addition, in order to satisfy the above-mentioned formulas (1) and (2), it is preferred to provide a small inclined surface on the surface of the pattern portion and the non-pattern portion. In the region where the intensity of reflected light for incident light with an incident angle of 35° to 80° is to be increased (hereinafter referred to as the high reflection region), a large number of small inclined surfaces with an inclination angle of 17° to 40° relative to the surface of the steel plate exist. The small inclined surface with an inclination angle of 17° to 40° preferably occupies an area of ​​60% or more relative to the total area of ​​the high reflection region.

[0133] The inclination angle can be obtained by measuring the surface shape of the pattern portion. As an apparatus for measuring the surface shape, a white light interferometer microscope (Contour GT I Elite manufactured by Bruker) can be cited. In addition, in order to calculate the proportion of a small inclined surface having an inclination angle of 17° to 40° using a white light interferometer microscope, for example, by finding the slope (inclination) Δi of each point in an area of ​​500 μm×500 μm or more on the surface of the pattern portion, the slope Δi is converted into a surface angle θ by the following formula (3): i , calculate the surface angle θ i The slope Δi is obtained by comparing the absolute value of the local slope dZ calculated by the following formula (5): i / dX i The same can be obtained from the following formula (5).

[0134] θ i =tan -1 Δi (3)

[0135] In the measurement of the surface shape, it is preferred to calculate the tilt angle from the surface shape from which the ripple component is removed using a high-pass filter with a cutoff value of 300 μm. When calculating the tilt angle, it is seriously affected by the sampling interval. Therefore, in this specification, the sampling interval is preferably greater than 1 μm and less than 4 μm. This is because if the sampling interval is too small, there is a concern that the uneven high-frequency components in the pickup noise may be excessively overestimated, and if the sampling interval is too large, there is a concern that the surface angle cannot be correctly estimated. It is preferred that the measurement area is larger, and it is preferred to use at least an area of ​​500 μm×500 μm for measurement.

[0136] In addition, in a slightly inclined surface having an inclination angle of 17° to 40°, the root mean square slope RΔq of the roughness curve is 17° to 40°. The root mean square slope RΔq of the roughness curve is expressed as the local slope dZ in JIS-B0601:2001. i / dX i The root mean square of is defined as follows: RΔq is the average value of the slope in the micro region.

[0137] The root mean square slope RΔq can be obtained by measuring the surface shape of the pattern portion, similarly to the tilt angle. An example of an apparatus for measuring the surface shape is a white light interferometer microscope (Contour GT I Elite manufactured by Bruker).

[0138] [Mathematical formula 1]

[0139]

[0140] In the above formula, n is the total number of measurement points, dZ i / dX i It refers to the i-th local slope. The local slope at each point of the measurement surface can be calculated by, for example, the following formula (5).

[0141] [Mathematical formula 2]

[0142]

[0143] In the formula, when one direction of the measurement surface is set as the X direction, X i is the position of the ith X direction, Z i is the i-th height, and ΔX is the sampling interval.

[0144] On the other hand, in the region where the intensity of reflected light for incident light with an incident angle of 35° to 80° is to be reduced (hereinafter referred to as the low reflection region), more micro-inclined surfaces having an inclination angle of less than 17° or more than 40° relative to the surface of the steel plate are present. The micro-inclined surfaces having an inclination angle of less than 17° or more than 40° preferably occupy more than 60% of the total area of ​​the low reflection region. That is, in the low reflection region, the micro-inclined surfaces having an inclination angle of 17° to 30° relative to the surface of the steel plate are reduced. In the low reflection region, the area ratio of the micro-inclined surfaces having an inclination angle of 17° to 40° is preferably less than 40% relative to the total area of ​​the low reflection region. In order to calculate the proportion of the micro-inclined surfaces having an inclination angle of less than 17° or more than 40°, the slope Δi of each point in the region of 500μm×500μm or more on the surface of the pattern portion is obtained in the same manner as above, and can be obtained by the above-mentioned formulas (3) to (5).

[0145] About reflection intensity I PH ,I BH ,I PM ,I BM ,I PL ,I BLIn the measurement, first, the coating surface is photographed with a digital optical camera to obtain video data. When photographing with a digital optical camera, the coating surface is photographed from a direction perpendicular to the coating surface. At this time, as the shooting light, the incident angle is greater than 0° and less than 35°, 35° to 80°, and greater than 80° and less than 90°, and each incident angle is photographed. It is preferred to make the difference between each incident angle be more than 10°. The shooting is preferably carried out in an environment that can block light other than the shooting light. The data of the light intensity in each pixel in the video data is extracted from the obtained video data. The video data may deviate due to individual differences in digital optical cameras, so histogram correction can also be performed to make the brightness of the image consistent with the visual situation. Generally speaking, the data of the light intensity of the pixel is represented by 256 levels of grayscale light and dark data with 0 as black and 255 as white, so the data is extracted. Then, the average value of the brightness of the pixels contained in the pattern portion is taken as the reflection intensity I PH ,I PM ,I PL In addition, the average value of the brightness of the pixels contained in the non-pattern portion is taken as the reflection intensity I BH ,I BM ,I BL . From these reflection intensities, |I PH -I BH | / |I PM -I BM |and|I PL -I BL | / |I PM -I BM |value.

[0146] [Method for producing hot-dip coated steel sheet]

[0147] Next, a method for producing the hot-dip plated steel sheet according to the present embodiment will be described.

[0148] The hot-dip plated steel sheet of this embodiment is hot-dip plated on a steel sheet manufactured through steelmaking, casting, and hot rolling. In addition, after the hot rolling, pickling, hot-rolled sheet annealing, cold rolling, cold-rolled sheet annealing, and finally hot-dip plated may be performed. In addition, it is specified that the hot-dip plated steel sheet is performed by a continuous hot-dip plated steel sheet continuously passing through a hot-dip plated bath.

[0149] The hot-dip coating bath preferably contains Al: 4 to 22 mass %, Mg: 1.0 to 10 mass %, and the remainder contains Zn and impurities. In addition, the hot-dip coating bath may contain Al: 4 to 22 mass %, Mg: 1.0 to 10 mass %, and the remainder is composed of Zn and impurities. In addition, the hot-dip coating bath may contain Si: 0.0001 to 2 mass %, and may contain any one or more of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, and C in a total of 0.0001 to 2 mass %.

[0150] The temperature of the hot-dip coating bath varies depending on the composition, but is preferably in the range of 400 to 500° C. This is because a desired hot-dip coating layer can be formed as long as the temperature of the hot-dip coating bath is in this range.

[0151] The amount of hot-dip coating can be adjusted by adjusting the steel sheet lifted from the hot-dip coating bath by means of gas friction contact or the like. It is preferred that the amount of hot-dip coating be adjusted to a total of 30 to 600 g / m2 on both sides of the steel sheet. 2 The range of adjustment can be adjusted. 2 The corrosion resistance of the hot-dip galvanized steel sheet decreases when the coating weight exceeds 600 g / m 2 When hot-dip galvanizing is performed, the molten metal attached to the steel sheet sags and the hot-dip galvanizing surface cannot be made smooth, which is not preferred.

[0152] After forming the hot-dip coating, the pattern portion and the non-pattern portion are formed by providing a micro-slant surface at the planned formation position of the pattern portion and the non-pattern portion on the coating surface.

[0153] In the region where the intensity of reflected light for incident light with an incident angle of 35° to 80° is to be increased, a large number of micro-inclined surfaces having an inclination angle of 17° to 40° relative to the surface of the steel plate are provided. The micro-inclined surfaces having an inclination angle of 17° to 40° preferably occupy an area of ​​60% or more relative to the total area of ​​the region.

[0154] On the other hand, in the region where the intensity of reflected light for incident light with an incident angle of 35° to 80° is to be reduced, a large number of micro-inclined surfaces having an inclination angle of less than 17° or more than 40° relative to the steel plate surface are provided. The micro-inclined surfaces having an inclination angle of less than 17° or more than 40° preferably occupy 60% or more of the total area of ​​the region.

[0155] The above-mentioned minute inclined surface can be formed by roller forming, that is, by pressing a roller against the hot-dip coating surface and transferring the surface shape of the roller to the hot-dip coating, and the roller adjusts the surface shape of the roller surface in a manner that can form an inclined surface with the above-mentioned inclination angle.

[0156] In addition, it is best to transfer when the surface temperature of the hot-dip coating is within the range of 250 to 300°C. If the surface temperature of the hot-dip coating during roller transfer is lower than 250°C, it is difficult to form a clear pattern portion because the hot-dip coating does not soften, so it is not preferred. In addition, if the surface temperature of the hot-dip coating exceeds 300°C, the hot-dip coating is greatly softened during roller transfer, so there is a concern that the pattern portion and the non-pattern portion cannot be clearly distinguished, so it is not preferred.

[0157] When a chemical conversion treatment layer is formed on the surface of the hot-dip coating layer, the hot-dip coated steel sheet after the hot-dip coating layer is subjected to chemical conversion treatment. The type of chemical conversion treatment is not particularly limited, and a known chemical conversion treatment can be used.

[0158] When a coating layer is formed on the surface of the hot-dip coating layer or the surface of the chemical conversion treatment layer, the hot-dip coated steel sheet after the hot-dip coating layer or the chemical conversion treatment layer is subjected to a coating treatment. The type of coating treatment is not particularly limited, and a known coating treatment can be used.

[0159] As an example of chemical conversion treatment, a chemical conversion treatment using a chemical conversion treatment agent can be exemplified, the chemical conversion treatment agent containing a phthalocyanine pigment coated with at least one of a resin and a surfactant. As the chemical conversion treatment agent, specifically, an aqueous coating agent can be used, the aqueous coating agent having polyurethane resin particles and ethylene-unsaturated carboxylic acid copolymer resin particles containing at least one of a silanol group and an alkoxysilyl group, silicon oxide particles, an organic titanium compound and the above-mentioned phthalocyanine pigment, the content of the phthalocyanine pigment relative to the total of 100 parts by mass of the polyurethane resin particles and the ethylene-unsaturated carboxylic acid copolymer resin particles, and the primary particle size of the phthalocyanine pigment is 0.01 to 1.0 μm. The hot-dip coating layer subjected to such chemical conversion treatment is colored by the phthalocyanine pigment, thereby being able to impart a preferred appearance decorativeness to the coating surface, and further being able to improve the corrosion resistance and weather resistance of the formed chemical conversion coating.

[0160] According to this embodiment, when light is incident from a specific direction, the pattern such as text and design displayed on the surface of the coating layer can be recognized in human vision, and it may be difficult to recognize the pattern when light is incident from other directions. In addition, in this embodiment, by pressing a roller with an adjusted surface shape on the surface of the hot-dip coating layer, the surface shape of the roller is transferred to the hot-dip coating layer, so that the range of the pattern part or the non-pattern part can be formed into an intentional or artificial shape, and the pattern part can be configured in a manner that becomes any one of a straight line part, a curve part, a dot part, a figure, a number, a symbol or a text, or a shape composed of two or more of them. Thus, without printing or painting the surface of the hot-dip coating layer, a variety of pattern designs, trademarks, and other identification marks can be displayed, and the recognizability and design of the origin of the steel plate can be improved. In addition, the pattern part can also be used to give the hot-dip coated steel plate information required for engineering management and inventory management and any information required by the user. Thus, it can also help to improve the productivity of the hot-dip coated steel plate.

[0161] Conventionally, when printing characters and designs on the surface of the coating by embossing ink, although the cost and time can be relatively reduced, the reactivity of the ink and the hot-dip coating needs to be considered. In addition, when grinding the hot-dip coating to produce a pattern design, although the durability of the pattern design is excellent, measures need to be taken to consider the thickness of the hot-dip coating corresponding to the grinding.

[0162] Example

[0163] Next, an embodiment of the present invention is described. After the steel plate is degreased and washed with water, the hot-dip plated steel plates No. 1 to 47 shown in Tables 2A to 3B are manufactured by performing reduction annealing, bath immersion, adhesion control, and cooling. Next, rollers A to F having a square pattern with a side length of 50 mm are pressed against the surface of the hot-dip plated layer in a state where the surface temperature of the hot-dip plated layer reaches 250 to 300°C, thereby forming a pattern portion. The details of rollers A to F having a square pattern are shown in Table 1. The area with the square pattern is regarded as the pattern portion, and the area outside the square pattern is regarded as the non-pattern portion. Furthermore, the ratio of the tiny inclined surfaces on the surface of the pattern portion and the non-pattern portion was measured by the above method, and the measurement results were consistent with the results in Table 1.

[0164] Table 1

[0165] Roller Pattern Department Non-pattern part A Among the surface irregularities, 80% have an inclination of 17 to 30 degrees. Among the surface irregularities, more than 90% of the inclinations are 0 to 5° B 80% of the surface irregularities have an inclination of 30 to 40° Among the surface irregularities, more than 90% of the inclinations are 0 to 5° C 80% of the surface irregularities have an inclination of 30 to 40° Among the surface irregularities, 60% of the inclinations are 0 to 15° D Among the surface irregularities, 60% have an inclination of 17 to 30 degrees. Among the surface irregularities, more than 90% of the inclinations are 0 to 5° E 80% of the surface irregularities have an inclination of 40 to 45 degrees. Among the surface irregularities, more than 90% of the inclinations are 0 to 5° F Among the surface irregularities, 40% have an inclination of 17 to 30 degrees. Among the surface irregularities, more than 90% of the inclinations are 0 to 5°

[0166] In addition, a Zn-Al-Mg hot-dip plated steel sheet was produced in the same manner as above. Then, a square pattern with a side length of 50 mm was printed on the hot-dip plated surface by inkjet printing. The results are shown as No. 48 in Table 2B and Table 3B.

[0167] In addition, a Zn-Al-Mg hot-dip plated steel sheet was produced in the same manner as above. Then, the hot-dip plated surface was ground to form a square pattern with a side length of 50 mm. The results are shown as No. 49 in Table 2B and Table 3B.

[0168] For the obtained hot-dip galvanized steel sheet, |I PH -I BH | / |I PM -I BM |and|I PL -I BL | / |I PM -I BM |. Specifically, the imaging data is obtained by photographing the coating surface of the coated steel plate with a digital optical camera. When photographing with a digital optical camera, the coating surface is photographed from a direction perpendicular to the coating. At this time, as the photographing light, light with an incident angle greater than 0° and less than 35°, 35° to 80°, and greater than 80° and less than 90° is used, and photographing is performed at each incident angle. The incident angles differ by more than 10°. The light intensity data of each pixel is extracted from the obtained imaging data. Generally speaking, the light intensity data of a pixel is represented by 256 levels of grayscale light and dark data with 0 as black and 255 as white, so the data is extracted. Then, the average value of the light intensity of the pixels contained in the pattern portion is taken as the reflection intensity I PH ,I BH ,I PM ,I BM ,I PL ,I BL From these reflection intensities, we can find |I PH -I BH | / |I PM -I BM |and|I PL -I BL | / |I PM -I BM |value.

[0169] Furthermore, in an example where it is difficult to distinguish the boundary between the pattern portion and the non-pattern portion, it is assumed that the portion corresponding to the square pattern on the roller surface is the pattern portion, and |I PH -I BH | / |I PM -I BM |and|I PL -I BL | / |I PM -I BM |value.

[0170] [Identification]

[0171] The initial state of the test plate with a square pattern portion just after manufacture was used as the object, and visual evaluation was performed based on the following judgment criteria. In the initial state, as the incident direction of the light during observation, the incident angle of light is greater than 0° and less than 35°, 35° to 80°, and greater than 80° and less than 90°, and the recognition when visually recognized from the normal direction of the plated surface at this time is evaluated. A (excellent) to C (general) are defined as qualified.

[0172] A (excellent): Almost unrecognizable with light having an incident angle of 0° or more and less than 35° and more than 80° and less than 90°, but clearly recognizable with light having an incident angle of 35° to 80°.

[0173] B (good): It is difficult to visually recognize with light having an incident angle of 0° or more and less than 35° and more than 80° and less than 90°, but it is visually recognized with light having an incident angle of 35° to 80°.

[0174] C (fair): It is difficult to visually recognize at any incident angle of light, but it is barely visually recognized at an incident angle of 35° to 80°.

[0175] D (poor): The image cannot be visually recognized at any incident angle of light, or the image can be visually recognized at any incident angle of light.

[0176] [Corrosion resistance]

[0177] The test plate was cut into 150×70 mm and subjected to the corrosion acceleration test CCT according to JASO-M609. After 30 cycles of the test, the rust generation was investigated and evaluated based on the following criteria: A (excellent) to C (fair) were defined as acceptable.

[0178] A (excellent): No rust occurs and the beautiful pattern design appearance is maintained.

[0179] B (Good): No rust occurs, but minor appearance changes can be seen.

[0180] C (Fair): No rust occurs, but some degree of appearance change can be seen.

[0181] D (poor): The appearance quality of the pattern portion and the non-pattern portion is significantly degraded and cannot be distinguished visually.

[0182] As shown in Tables 2A to 3B, the Zn-Al-Mg hot-dip plated steel sheets of the present invention examples No. 1 to No. 41 are excellent in both visibility and corrosion resistance. However, Nos. 40 and 41 have slightly lower visibility than the other examples.

[0183] On the other hand, as shown in Table 2B and Table 3B, in No. 42, the average composition of the hot-dip coating layer has an insufficient Al content, and therefore the corrosion resistance of the hot-dip coating layer is insufficient.

[0184] In No. 43, the average composition of the hot-dip coating layer contained excessive Al. Therefore, the corrosion resistance of the hot-dip coating layer was insufficient.

[0185] In No. 44, the average composition of the hot-dip coating layer has an insufficient Mg content, and therefore the corrosion resistance of the hot-dip coating layer is insufficient.

[0186] In No. 45, the average composition of the hot-dip coating had an excessive Mg content, so scum was generated in the coating bath, and the corrosion resistance of the hot-dip coating was insufficient.

[0187] Since the roller surface shapes of No. 46 and No. 47 were not appropriate, the conditions of equations (1) and (2) were not satisfied and the identification was poor.

[0188] No. 48, in which a square pattern portion was printed by an inkjet method, was exposed outdoors for 6 months, and the pattern portion became thinner and the visibility decreased.

[0189] In addition, although No. 49 in which a square pattern was formed by grinding was within the range evaluated according to the corrosion resistance evaluation criteria and had no problem, the corrosion resistance of the ground portion was locally reduced due to the reduction in the plating thickness of the ground portion, and thus it was not a preferred appearance.

[0190] Furthermore, the coating layers of Nos. 1 to 41 and 46 to 49 contain an Al phase and a ternary eutectic structure of Al / Zn / MgZn2.

[0191] In addition, the appearance decorativeness was confirmed by forming a chemical conversion treatment film on the surface of the plated layer of No. 38 to 41. The chemical conversion treatment film was formed by chemical conversion treatment using a chemical conversion treatment agent containing a phthalocyanine pigment. As the chemical conversion treatment agent, an aqueous coating agent was used, and the aqueous coating agent had: polyurethane resin particles and ethylene-unsaturated carboxylic acid copolymer resin particles containing silanol groups and alkoxysilyl groups, silicon oxide particles, an organic titanium compound and Cu phthalocyanine, wherein the content of the Cu phthalocyanine pigment was 0.01 to 10 parts by mass relative to a total of 100 parts by mass of the polyurethane resin particles and the ethylene-unsaturated carboxylic acid copolymer resin particles, and the primary particle size of the Cu phthalocyanine was 0.01 to 1.0 μm.

[0192] The identification properties of Nos. 38 to 41 on which the chemical conversion treatment films were formed were evaluated. As a result, all of the evaluations were "A (excellent)", indicating that the identification properties were further improved by providing the chemical conversion treatment films containing Cu phthalocyanine.

[0193] Table 2A

[0194]

[0195] Table 2B

[0196]

[0197] The underline indicates outside the scope of the present invention.

[0198] Table 3A

[0199]

[0200] Table 3B

[0201]

[0202] The underline indicates outside the scope of the present invention.

Claims

1. A hot-dip plated steel sheet comprising a steel sheet and a hot-dip plated layer formed on a surface of the steel sheet, wherein: The hot-dip coating layer contains, as an average composition, 4 to 22 mass % of Al, 1.0 to 10 mass % of Mg, and the remainder contains Zn and impurities. The hot-dip plated layer has a pattern portion and a non-pattern portion, For incident light having an incident angle in the range of 0° to less than 90° relative to the normal direction of the surface of the steel plate, the relationship between the reflected light of the pattern portion in the normal direction and the reflected light of the non-pattern portion in the normal direction satisfies the following equations (1) and (2): PH -I BH | / |I PM -I BM |<1.0 (1) |I PL -I BL | / |I PM -I BM |<1.0 (2) In the formula, I PH : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°, I BH : Reflection intensity of the non-pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°, I PM : Reflection intensity of the pattern portion in the normal direction for incident light at an incident angle of 35° to 80°, I BM : Reflection intensity of the non-pattern part in the normal direction for incident light with an incident angle of 35° to 80°, I PL : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle exceeding 80° and less than 90°, I BL : Reflection intensity of the non-pattern portion for incident light with an incident angle of more than 80° and less than 90° in the normal direction.

2. A hot-dip plated steel sheet comprising a steel sheet and a hot-dip plated layer formed on a surface of the steel sheet, wherein: The hot-dip coating layer contains, as an average composition, 4 to 22 mass % of Al, 1.0 to 10 mass % of Mg, and the remainder contains Zn and impurities. further comprising one or two selected from the following Group A and Group B, The hot-dip plated layer has a pattern portion and a non-pattern portion, For incident light having an incident angle in the range of 0° to less than 90° relative to the normal direction of the surface of the steel plate, the relationship between the reflected light of the pattern portion in the normal direction and the reflected light of the non-pattern portion in the normal direction satisfies the following equations (1) and (2): PH -I BH | / |I PM -I BM |<1.0 (1) |I PL -I BL | / |I PM -I BM |<1.0 (2) [Group A] Si: 0.0001 to 2 mass% [Group B] Any one or more of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, and C: 0.0001 to 2% by mass in total In the formula, I PH : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°, I BH : Reflection intensity of the non-pattern portion in the normal direction for incident light with an incident angle of 0° or more and less than 35°, I PM : Reflection intensity of the pattern portion in the normal direction for incident light at an incident angle of 35° to 80°, I BM : Reflection intensity of the non-pattern part in the normal direction for incident light with an incident angle of 35° to 80°, I PL : Reflection intensity of the pattern portion in the normal direction for incident light with an incident angle exceeding 80° and less than 90°, I BL : Reflection intensity of the non-pattern portion for incident light with an incident angle of more than 80° and less than 90° in the normal direction.

3. The hot-dip coated steel sheet according to claim 1 or 2, characterized in that: The pattern portion is arranged so as to form any one of a straight line portion, a curved line portion, a dot portion, a figure, a number, a symbol, or a character, or a shape formed by combining two or more of them.

4. The hot-dip coated steel sheet according to claim 1 or 2, characterized in that: The adhesion amount of the hot-dip coating is 30 to 600 g / m2 on both sides of the steel plate. 2 .

5. The hot-dip coated steel sheet according to claim 3, characterized in that: The adhesion amount of the hot-dip coating is 30 to 600 g / m2 on both sides of the steel plate. 2 .

6. The hot-dip coated steel sheet according to claim 2, wherein: The hot-dip coating layer has an average composition containing the group A in mass %.

7. The hot-dip coated steel sheet according to claim 2, wherein: The hot-dip coating layer has an average composition containing the B group in mass %.

8. The hot-dip coated steel sheet according to claim 1 or 2, wherein: The proportion of the inclined surface having an inclination angle of 17° to 40° in the pattern portion is 60% or more.

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