KR20230084519A - Zn-based coated steel sheet - Google Patents

Abstract

A steel sheet, a Zn-based plating layer containing Al and Zn disposed on at least one side of the steel sheet, and at least one chromate-free chemical conversion treatment layer disposed on the Zn-based plating layer and having an adhesion amount of 0.1 to 15 g/m 2 per side, The conversion layer contains a resin and a yellow colorant, and b* is 2 or more and 60 or less, b*/a* when the appearance is evaluated in the CIE1976 (L*, a*, b*) color space. is -3 or more and 3 or less, 60 degree mirror gloss G _s (60 °) is 50 to 200, light is incident toward the surface from an angle of 60 ° from the surface of the converted layer, and light reflected from the surface is Let L* obtained when light is received at an angle of 135° from the surface is L*1, light is incident toward the surface from an angle of 120° from the surface, and light reflected from the surface is received at an angle of 135° from the surface. Zn-based coated steel sheet that satisfies Equation 1 (10 ≥ L * 1 / L * 2 ≥ 2) when L * obtained when L * 2 is denoted.

Description

Zn-based coated steel sheet

The present invention relates to a Zn-based coated steel sheet.

As a coated steel sheet having good corrosion resistance, there is a Zn-based coated steel sheet as the most used coated steel sheet. These Zn-based coated steel sheets are used in various manufacturing industries such as automobile, home appliance, and building materials fields. Among them, since plating with addition of Al has high corrosion resistance, its usage has been increasing in recent years.

As an example of a Zn-based coated steel sheet developed for the purpose of improving corrosion resistance, Patent Document 1 describes a hot-dip Zn-Al-Mg-Si coated steel sheet. This plated steel sheet has a characteristic that it is also excellent in external aesthetics because the external appearance shows a pear skin pattern.

By the way, conventionally, in order to impart a higher level of anti-corrosive function to Zn-based coated steel sheets, it is widely practiced to perform chromate treatment using hexavalent chromate or the like after plating, and if necessary, design, stain resistance, lubricity, etc. In order to impart a high value-added function, coating with an organic resin was performed. However, there is a movement to refrain from using chromate treatment against the backdrop of heightened environmental problems. Therefore, there is a surface-treated plated steel sheet described in Patent Literature 2 below for the purpose of imparting a high-level rust-preventive function simply by performing only one-layer treatment of a resin-based coating without performing chromate treatment. Corrosion resistance can be further improved by using the film described in Patent Literature 2 below.

However, in recent years, there has been a demand to further improve the aesthetic appearance of the Zn-based coated steel sheet containing Al. Specifically, the surface of the Zn-based plated steel sheet shows an achromatic pear-shell pattern in which glossy and white parts are mixed, but there is a desire to have a golden appearance in order to give a splendid appearance. .

Japanese Patent No. 3179446 Japanese Unexamined Patent Publication No. 2006-52462

The present invention has been made in view of the above circumstances, and has as its object to provide a Zn-based coated steel sheet that exhibits a high-quality golden-colored appearance and has improved corrosion resistance in a Zn-based coated steel sheet containing Al.

In order to solve the above problems, the present inventors have intensively studied, and after reducing the surface roughness of the Zn-based plating layer to give it a metallic luster, by incorporating a yellow colorant into the converted layer, it can be seen as gold to the naked eye. Found out. The present invention adopts the following constitution.

[1] A steel plate,

a Zn-based plating layer containing 0.05 to 60% by mass of Al and Zn disposed on at least one side of the steel sheet;

At least one chromate-free chemical conversion treatment layer is provided on the Zn-based plating layer and has an adhesion amount of 0.1 to 15 g / m 2 per side,

The conversion layer contains a resin and a yellow colorant,

When the appearance is evaluated in the CIE1976 (L*, a*, b*) color space, b* is 2 or more and 60 or less, and b*/a* is -3 or more and 3 or less, and is specified in JIS Z 8741:1997. 60 degree mirror gloss G _s (60 °) is 50 to 200;

In a plane orthogonal to the surface of the converted layer, L obtained when light is incident toward the surface from an angle of 60° from the surface and light reflected from the surface is received at an angle of 135° from the surface Let * be L*1, in the plane, L obtained when light is incident toward the surface from an angle of 120° from the surface, and light reflected from the surface is received at an angle of 135° from the surface. When * is L*2, the Zn-based coated steel sheet wherein L*1 and L*2 satisfy Equation 1 below.

10≥L*1/L*2≥2 ... Equation 1

[2] The Zn-based plated steel sheet according to [1], wherein the yellow colorant is an azo yellow pigment or an iron oxide yellow pigment.

[3] The Zn-based plated steel sheet according to [1] or [2], wherein the content of the yellow colorant in the converted layer is 0.1 to 10% by mass.

[4] The Zn-based plated steel sheet according to any one of [1] to [3], wherein L*1 and L*2 satisfy Formula 2 below.

7≥L*1/L*2≥4 ... Equation 2

[5] The Zn-based plating according to any one of [1] to [4], wherein the converted layer contains 1 to 20% by mass of metal oxide particles having an average particle diameter of 5 to 200 nm and a refractive index of 1.3 to 2.5. grater.

[6] The Zn-based plated steel sheet according to [5], wherein the metal oxide particles contain silica particles.

[7] The Zn-based plated steel sheet according to [5] or [6], wherein a mixing ratio of the yellow colorant and the metal oxide particles in the converted layer is in the range of 1 to 200.

[8] The Zn-based plated steel sheet according to any one of [1] to [7], wherein the arithmetic average roughness Ra of the surface of the Zn-based plating layer is 0.1 to 2.0 µm.

[9] The Zn according to any one of [1] to [8], wherein the arithmetic mean roughness Ra of the Zn-based plating layer is 0.5 to 2.0 μm, and the arithmetic mean height Sa of the converted layer is 5 nm to 100 nm. galvanized steel sheet.

[10] The Zn-based plated steel sheet according to any one of [1] to [9], wherein either or both of a Nb compound and a phosphoric acid compound are further contained in the chemical conversion layer.

[11] Of [1] to [10], wherein the resin in the converted layer is made of any one or more of polyolefin resins, fluororesins, acrylic resins, urethane resins, polyester resins, epoxy resins, and phenol resins. The Zn-based plated steel sheet according to any one of the preceding claims.

[12] The Zn-based plating layer contains, in average composition, Al: 4% by mass or more and 22% by mass or less, Mg: more than 1% by mass and 10% by mass or less, the remainder being Zn and impurities, [1] to The Zn-based plated steel sheet according to any one of [11].

[13] The Zn-based plated steel sheet according to any one of [1] to [12], wherein the Zn-based plating layer further contains Si: 0.0001 to 2% by mass in average composition.

[14] [1] to [13] characterized in that the Zn-based plating layer further contains 0.0001 to 2% by mass of any one or two or more of Ni, Sb, and Pb in an average composition in total. The Zn-based plated steel sheet according to any one of the above.

[15] Characterized in that the maximum value of L* is 1.2 times or more of the minimum value of L* when L* in the range of 0.5 mm in diameter centered on each point is measured for any 5 points on the plating surface. The Zn-based plated steel sheet according to any one of [1] to [14].

[16] In the Zn-based plating layer, a pattern portion and a non-pattern portion are formed so as to have a predetermined shape,

The pattern portion and the non-pattern portion each include one or two of a first region and a second region determined by any one of determination methods 1 to 5 below,

Any one of [1] to [15], wherein the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more. The Zn-based plated steel sheet described in.

[Decision method 1]

Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and in a plurality of areas partitioned by the virtual lattice lines, each area is measured within a circle having a diameter of 0.5 mm centered on the center of gravity of each area. Let it be A, and measure the L* value in each measurement area|region A. When 50 points are randomly selected from the obtained L* values and the average of 50 points of the obtained L* values is referred to as the reference L* value, the region in which the L* value is equal to or greater than the reference L* value is the first region, the reference L* A region that is less than the value is referred to as a second region.

[Decision method 2]

Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and in a plurality of areas partitioned by the virtual lattice lines, each area is measured within a circle having a diameter of 0.5 mm centered on the center of gravity of each area. Denoted as A, the L* value in each measurement region A is measured, and the region in which the L* value is 45 or more is referred to as a first region, and the region in which the L* value is less than 45 is referred to as a second region.

[Decision method 3]

Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and the arithmetic average surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual lattice lines. A region in which the obtained Sa is 1 μm or more is referred to as a first region, and a region in which Sa is less than 1 μm is referred to as a second region.

[Decision method 4]

By an X-ray diffraction method in which virtual grid lines are drawn on the surface of the Zn-based plating layer at intervals of 1 mm or 10 mm, and X-rays are incident on each of a plurality of regions partitioned by the virtual grid lines, for each region, The diffraction peak intensity I ₀₀₀₂ of the (0002) plane of the Zn phase and the diffraction peak intensity I _10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I ₀₀₀₂ /I _10-11 ) is called the orientation factor. do. An area in which the orientation ratio is 3.5 or more is referred to as a first area, and an area in which the orientation ratio is less than 3.5 is referred to as a second area.

[Decision method 5]

Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 1 mm, and then, a circle S centered on the center point G of each area is drawn for each of a plurality of areas partitioned by the virtual lattice lines. The diameter R of the circle S is set so that the total length of the surface boundary lines of the Zn-based plating layer included inside the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin among the diameters R of the circles S of the plurality of regions is referred to as the reference diameter Rave, and the region having the circle S having the diameter R less than the reference diameter Rave is referred to as the first region, and the diameter R is A region having a circle S equal to or larger than the reference diameter Rave is referred to as a second region.

[17] The Zn-based plated steel sheet according to any one of [1] to [16], wherein any one of Co, Fe, and Ni is present on the surface of the Zn-based plating layer.

ADVANTAGE OF THE INVENTION According to this invention, in the Zn-based plated steel sheet containing Al, it is possible to provide a Zn-based plated steel sheet that exhibits a high-quality golden-colored appearance and has improved corrosion resistance.

The present inventors made the converted layer contain a yellow colorant to color the converted layer yellow, and reduce the surface roughness of the Zn-based plating layer to show a metallic luster, so that the appearance of the Zn-based plating layer can be seen by the naked eye. I found out that it makes it look gold. However, if the yellow color is too dark, the appearance of metal on the surface of the plating layer becomes difficult to be visually recognized, and the overall appearance is yellow, and in the case where incident light is reflected on the surface of the plating layer or when incident light is reflected on the surface of the converted layer, Zn It was found that the way the color of the base plated layer was changed was changed, and it did not look gold. Therefore, as a result of further examination, the b* value and b*/a* when evaluated in the CIE1976 (L*, a*, b*) color space, and the 60-degree mirror gloss G _s (60 °) is controlled to be within a predetermined range, and light is incident toward the surface of the converted layer from an angle of 60° from the surface of the converted layer in a plane orthogonal to the surface of the converted layer, L* obtained when light reflected from the surface of the converted layer is received at an angle of 135° from the surface of the converted layer is referred to as L*1, and in the plane, the converted layer is viewed from an angle of 120° from the surface of the converted layer. When light is incident toward the surface of the converted layer and light reflected from the surface of the converted layer is received at an angle of 135° from the surface of the converted layer, L* obtained when L*2 is L*1 and L *2 was found to exhibit a golden appearance by controlling 10≧L*1/L*2≧2 (Equation 1). In addition, by controlling the relationship between b* value and b*/a*, 60 degree mirror gloss G _s (60°), and L*1 and L*2, an arbitrary shape such as a character is displayed on the surface of the coating layer. Even in this case, it was also found that an arbitrary shape becomes easy to see. As a result, it is not necessary to contain fine particles of gold or fine particles of metal exhibiting a golden color in the chemical conversion treatment layer, and a golden appearance can be obtained at low cost.

That is, the Zn-based plated steel sheet according to the embodiment of the present invention includes a steel sheet, a Zn-based plating layer containing 0.05 to 60% by mass of Al and Zn disposed on at least one side of the steel sheet, and disposed on the Zn-based plating layer, At least one layer of chromate-free chemical conversion treatment layer is provided with an adhesion amount of 0.1 to 15 g/m2 per side, the conversion treatment layer contains a resin and a yellow colorant, and the appearance is changed to CIE1976 (L*, a*, b* ) When evaluated in the color space, b* is 2 or more and 60 or less, b*/a* is -10 or more and -3 or less, and the 60 degree mirror gloss G _s (60°) specified in JIS Z 8741:1997 is 50 to 200, and in a plane orthogonal to the surface of the converted layer, light is incident toward the surface of the converted layer from an angle of 60° from the surface of the converted layer, and the light reflected from the surface of the converted layer is L* obtained when light is received at an angle of 135° from the surface of the converted layer is referred to as L*1, and light is incident toward the surface of the converted layer from an angle of 120° from the surface of the converted layer in the above plane. And when L* obtained when light reflected from the surface of the converted layer is received at an angle of 135° from the surface of the converted layer is L*2, L*1 and L*2 are 10≥L* It is a Zn-based plated steel sheet that satisfies 1/L*2≥2 (Equation 1).

In addition, in the Zn-based plated steel sheet of the present embodiment, it is preferable that the yellow colorant is an azo yellow pigment or an iron oxide yellow pigment.

In addition, in the Zn-based plated steel sheet of the present embodiment, it is preferable that the content of the yellow colorant in the chemical conversion treatment layer is 0.1 to 10% by mass.

In addition, in the Zn-based plated steel sheet of the present embodiment, it is preferable that L*1 and L*2 satisfy 7≥L*1/L*2≥4 (Equation 2).

In the Zn-based plated steel sheet of the present embodiment, it is preferable that the converted layer contain 1 to 20% by mass of metal oxide particles having an average particle diameter of 5 to 200 nm and a refractive index of 1.3 to 2.5.

In addition, in the Zn-based plated steel sheet of the present embodiment, it is preferable that the metal oxide particles contain silica particles.

In addition, in the Zn-based plated steel sheet of the present embodiment, it is preferable that the mixing ratio of the yellow colorant and the metal oxide particles is 1 to 200.

In addition, in the Zn-based plated steel sheet of the present embodiment, it is preferable that the arithmetic average roughness Ra of the surface of the Zn-based plating layer is 0.1 to 2.0 µm.

Further, in the Zn-based plated steel sheet of the present embodiment, it is preferable that the arithmetic average roughness Ra of the Zn-based plating layer is 0.5 to 2.0 µm and the arithmetic average height Sa of the converted layer is 5 nm to 100 nm.

[Zn-based coated steel sheet]

Hereinafter, the Zn-based plated steel sheet of the present embodiment will be described.

There is no particular limitation on the material of the steel sheet serving as the base of the Zn-based plating layer. As a material, general steel or the like can be used without particular limitation, Al-killed steel or some high-alloy steel can also be applied, and there is no particular limitation in shape. The Zn-based plating layer according to the present embodiment is formed by applying the hot-dip plating method described later to the steel sheet.

[Zn-based plating layer]

Next, the chemical composition of the Zn-based plating layer will be described.

The Zn-based plating layer is a Zn-based plating layer containing 0.05 to 60% by mass of Al and Zn. In addition, the Zn-based plating layer of the present embodiment preferably contains 4 to 22% by mass of Al and 1 to 10% by mass of Mg in average composition, and contains Zn and impurities as the remainder. More preferably, as an average composition, Al: 4-22 mass %, Mg: more than 1 mass % and 10 mass % or less are contained, and it is preferable to consist of Zn and impurities as the balance.

By containing 0.05% by mass or more of Al, the corrosion resistance of the Zn-based plating layer can be improved, and by setting the Al content to 60% by mass or less, the amount of Zn contained in the Zn-based plating layer is relatively increased, thereby sacrificing corrosion resistance. it becomes possible to secure Further, corrosion resistance and sacrificial corrosion resistance can be further improved by containing Al: 4 to 22% by mass, Mg: 1 to 10% by mass, balance: Zn, and impurities. The Zn-based plating layer may contain 40% by mass or more of Zn.

In addition, the Zn-based plating layer may contain Si: 0.001 to 2% by mass in average composition. In addition, the Zn-based plating layer has an average composition of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, C You may contain 0.001-2 mass % of any 1 type(s) or 2 or more types of these in total.

Next, as the Zn-based plating layer, the reason for limiting the components of the Zn-based plating layer, which contains 4 to 22% by mass of Al and 10% by mass or less of Mg, with the remainder being Zn and impurities, will be explained.

The content of Al is in the range of 4 to 22% by mass. Al should be contained in order to ensure corrosion resistance. When the content of Al in the Zn-based plating layer is 4% by mass or more, the effect of improving corrosion resistance becomes higher. When the content of Al is 22% by mass or less, the effect of improving corrosion resistance is easily ensured while maintaining a golden appearance. From the viewpoint of corrosion resistance, it is preferably 5 to 18% by mass. More preferably, it is set as 6-16 mass %.

The content of Mg is in the range of more than 1% by mass and 10% by mass or less. What is necessary is just to contain Mg in order to improve corrosion resistance. When the content of Mg in the Zn-based plating layer is more than 1% by mass, the effect of improving corrosion resistance becomes higher. When the content of Mg is 10% by mass or less, generation of dross in the plating bath is suppressed, and it becomes easy to stably manufacture a Zn-based plated steel sheet. From the viewpoint of the balance between corrosion resistance and dross generation, the Mg content is preferably 1.5 to 6% by mass. More preferably, the content of Mg is in the range of 2 to 5% by mass.

Although the Zn-based plating layer containing Mg tends to turn black, on the other hand, when a conversion treatment layer containing a yellow colorant is disposed on the plating layer, the color depth is created by blackening, so there is an advantage that a more luxurious golden color is obtained. there is.

The content of Al and Mg may be 0%, respectively. That is, the Zn-based plating layer of the Zn-based plated steel sheet of the present embodiment is not limited to the Zn-Al-Mg hot-dip plating layer, and may be a Zn-Al-based hot-dip plating layer.

Further, the Zn-based plating layer may contain Si in the range of 0.0001 to 2% by mass.

Since Si may improve the adhesion of the Zn-based plating layer, you may contain Si. Since the effect of improving adhesion is expressed by containing Si at 0.0001% by mass or more, preferably 0.001% or more, more preferably 0.01% or more, it is preferable to contain 0.0001% by mass or more of Si. On the other hand, since the effect of improving coating adhesiveness is saturated even if Si is contained exceeding 2 mass %, content of Si is made into 2 mass % or less. From the viewpoint of plating adhesion, it may be in the range of 0.001 to 1% by mass, and the content of Si may be in the range of 0.01 to 0.8% by mass.

Among the Zn-based plating layers, as an average composition, one of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, and C You may contain 0.001-2 mass % of species or 2 or more types in total. By containing these elements, corrosion resistance can be further improved. REM is one or two or more rare earth elements having atomic numbers 57 to 71 in the periodic table.

The rest of the chemical components of the Zn-based plating layer are zinc and impurities. Impurities include those that are unavoidably included in zinc or other metals, and those that are included when steel is dissolved in a plating bath.

In addition, the average composition of the Zn-based plating layer can be measured by the following method. First, after removing the surface layer coating film with a coating film release agent that does not erode plating (eg, Neo River SP-751 manufactured by Sansai Kako Co., Ltd.), an inhibitor (eg, Hibiron manufactured by Sugimura Chemical Industry Co., Ltd.) containing It can be obtained by dissolving the Zn-based plating layer with hydrochloric acid and subjecting the obtained solution to inductively coupled plasma (ICP) emission spectroscopy analysis. When removing the surface layer coating film, it is preferable to remove the chemical conversion treatment layer together.

Next, the structure of the Zn-based plating layer will be described. The structure described below is a structure in the case where the Zn-based plating layer contains 4 to 22% by mass of Al, 1 to 10% by mass of Mg, and 0 to 2% by mass of Si as an average composition.

The Zn-based plating layer containing Al, Mg, and Zn includes [Al phase] and [Al/Zn/MgZn ₂ ternary eutectic structure]. [Al/Zn/MgZn ₂ ternary eutectic structure] has a form in which [Al phase] is included. Further, [MgZn ₂ phase] or [Zn phase] may be contained in the substrate of [Al/Zn/MgZn ₂ ternary eutectic structure]. Further, when Si is added, [Mg ₂ Si phase] may be contained in the base material of [Al/Zn/MgZn ₂ ternary eutectic structure].

Here, [a ternary eutectic structure of Al/Zn/MgZn ₂ ] means a ternary eutectic structure of an Al phase, a Zn phase, and an intermetallic compound MgZn ₂ phase, and the Al phase forming this ternary eutectic structure is, for example, In the Al-Zn-Mg ternary equilibrium diagram, it corresponds to the "Al"phase" (an Al solid solution in which Zn is dissolved and a small amount of Mg is included) at a high temperature. The Al" phase at a high temperature is normal temperature In , it usually appears as a fine Al phase and a fine Zn phase separated. Further, the Zn phase in the ternary eutectic structure is a Zn solid solution in which a small amount of Al is dissolved and, in some cases, a small amount of Mg is also dissolved. The MgZn ₂ phase in the ternary eutectic structure is an intermetallic compound phase present in the vicinity of Zn: about 84% by mass in the Zn-Mg binary system equilibrium diagram. As seen from the phase diagram, each phase does not contain other additive elements, or even if it does, it is considered to be in a very small amount, but the amount cannot be clearly distinguished by ordinary analysis. In this specification, it is represented as [Al/Zn/MgZn ₂ ternary eutectic structure].

In addition, [Al phase] is a phase that has a clear boundary in the substrate of the ternary eutectic structure and looks like an island, and this is, for example, "Al" at a high temperature in the equilibrium diagram of the ternary system of Al-Zn-Mg phase” (an Al solid solution that dissolves Zn and contains a small amount of Mg). The Al” phase at this high temperature differs in the amount of dissolved Zn or Mg depending on the concentration of Al or Mg in the plating bath. The Al" phase at this high temperature is usually separated into a fine Al phase and a fine Zn phase at room temperature, but the shape of the island phase seen at room temperature can be regarded as maintaining the shape of the Al" phase at high temperature. As far as the phase diagram shows, this phase does not contain other additive elements, or even if it does, it is considered to be in a very small amount, but it cannot be clearly distinguished by ordinary analysis. A phase that maintains the shape of the Al" phase is referred to as [Al phase] in this specification. This [Al phase] can be clearly distinguished from the Al phase forming the above ternary eutectic structure in microscopic observation.

In addition, [Zn phase] is a phase that has a clear boundary in the base material of the above-mentioned ternary eutectic structure and looks like an island, and in fact, there is also a small amount of Al and also a small amount of Mg solid solution. As far as the phase diagram shows, other additive elements are not dissolved in this phase, or even if they are dissolved, it is considered to be in an extremely small amount. This [Zn phase] can be clearly distinguished from the Zn phase forming the above ternary eutectic structure in microscopic observation. [Zn phase] may be contained in the Zn-based plating layer of the present invention depending on manufacturing conditions, but in the experiment, almost no effect was observed on the improvement of corrosion resistance of the processed part, so even if [Zn phase] is contained in the plating layer, there is no particular problem. does not exist.

In addition, [MgZn ₂ phase] is a phase that has a clear boundary in the substrate of the above-mentioned ternary eutectic structure and looks like an island, and in fact, there is also a small amount of Al solid solution. As far as the phase diagram shows, other additive elements are not dissolved in this phase, or even if they are dissolved, it is considered to be in an extremely small amount. This [MgZn ₂ phase] can be clearly distinguished from the MgZn ₂ phase forming the ternary eutectic structure in microscopic observation. [MgZn ₂ phase] may not be included in the Zn-based plating layer of the present invention depending on manufacturing conditions, but it is included in the Zn-based plating layer under most manufacturing conditions.

In addition, [Mg ₂ Si phase] is a phase that has a clear boundary in the solidification structure of the Zn-based plating layer when Si is added and looks like an island. As far as the phase diagram shows, Zn, Al, and other additive elements are not dissolved, or even if they are dissolved, it is considered to be in a very small amount. This [Mg ₂ Si phase] can be clearly distinguished in microscopic observation among Zn-based plating layers.

Further, it is preferable to have any one of Co, Fe, and Ni on the surface of the Zn-based plating layer. Co, Fe, and Ni adhere to the surface of the Zn-based plating layer by performing Co treatment, Fe treatment, or Ni treatment after formation of the Zn-based plating layer. When these elements exist on the surface of the Zn-based plating layer, blackening resistance can be improved.

Also, the arithmetic mean roughness Ra of the surface of the Zn-based plating layer is preferably 0.1 to 2.0 µm. Moreover, 0.5-2.0 micrometers may be sufficient as arithmetic mean roughness Ra. When Ra is 2.0 μm or less, the metallic luster of the Zn-based plating layer is improved to exhibit a more beautiful gold color. Also, since the effect is saturated even if Ra is less than 0.1 μm, the lower limit may be 0.1 μm or more. The arithmetic mean roughness Ra of the Zn-based plating layer is measured and calculated with a 3D laser microscope (manufactured by Keyence Corporation). Using a 20x standard lens, the height Z is measured at a measurement interval of 50 μm. It is preferable to set the measurement score to 100 points. The arithmetic mean roughness Ra is calculated from the following formula 3 using the height Z1 to height Z100 for the height Z 100 points obtained by making the measurement score 100 points. Zave is the average of 100 height Z points.

Ra=1/100×Σ[x=1→100] (|Height Zx-Zave|) ... Equation 3

[Conversion treatment layer]

Next, the conversion layer will be described. Resin and a yellow coloring agent are contained in the chemical conversion layer of this embodiment. The chemical conversion layer of this embodiment is a film obtained by applying an aqueous composition containing a resin and a yellow colorant to a Zn-based plating layer formed on a steel sheet and drying it.

(profit)

It is preferable that the resin contained in the chemical conversion layer consists of any one or more types of resins among polyolefin resins, fluororesins, acrylic resins, urethane resins, polyester resins, epoxy resins, and phenol resins. These resins may be water-soluble resins, or may be resins (water-dispersible resins) that are inherently insoluble in water but can be micro-dispersed in water like emulsions or suspensions.

The polyolefin resin is not particularly limited. For example, after radical polymerization of ethylene and an unsaturated carboxylic acid such as methacrylic acid, acrylic acid, maleic acid, fumaric acid, itaconic acid, and crotonic acid under high temperature and high pressure, ammonia or an amine compound , a metal compound such as KOH, NaOH, or LiOH, or one obtained by neutralizing with ammonia or an amine compound containing the metal compound and subjecting it to water oxidation.

The fluororesin is not particularly limited, and examples thereof include homopolymers and copolymers of fluoroolefins. In the case of a copolymer, a copolymer of a fluoroolefin and a fluorine-containing monomer other than a fluoroolefin and/or a monomer having no fluorine atom is exemplified.

The acrylic resin is not particularly limited, and examples thereof include unsaturated monomers such as styrene, alkyl (meth)acrylates, (meth)acrylic acid, hydroxyalkyl (meth)acrylates, and alkoxysilane (meth)acrylates. What is obtained by carrying out radical polymerization using a polymerization initiator in aqueous solution is mentioned. The polymerization initiator is not particularly limited, and examples thereof include persulfates such as potassium persulfate and ammonium persulfate, and azo compounds such as azobiscyanovaleric acid and azobisisobutyronitrile.

The urethane resin is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether, glycerin, trimethylolethane, and those obtained by reacting polyhydric alcohols such as trimethylolpropane with diisocyanate compounds such as hexamethylene diisocyanate, isophorone diisocyanate, and tolylene diisocyanate, followed by chain extension with diamine or the like, followed by water oxidation.

The polyester resin is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether, glycerin, and trimethylolethane. Ammonia neutralization with an amine compound or the like, and those obtained by water oxidation.

The epoxy resin is not particularly limited, and examples thereof include bisphenol A type epoxy resins, bisphenol F type epoxy resins, resorcinol type epoxy resins, hydrogenated bisphenol A type epoxy resins, hydrogenated bisphenol F type epoxy resins, and resorcinol type epoxy resins. Epoxy resins such as epoxy resins and novolac-type epoxy resins are reacted with amine compounds such as diethanolamine and N-methylethanolamine to neutralize them with organic or inorganic acids. After polymerization, neutralization with ammonia, an amine compound, etc., and the thing obtained by water oxidation are mentioned.

The phenolic resin is not particularly limited, and examples thereof include methylolized phenolic resins obtained by addition reaction of aromatics such as phenol, resorcinol, cresol, bisphenol A, and paraxylylenedimethylether with formaldehyde in the presence of a reaction catalyst. and those obtained by reacting a phenol resin with amine compounds such as diethanolamine and N-methylethanolamine and neutralizing it with an organic acid or an inorganic acid.

It is preferable to contain resin in a ratio of 20% by mass or more in the converted layer. By setting the content of the resin to 20% by mass or more, the converted layer itself does not become brittle, and the Zn-based plating layer can be coated stably. In addition, the chemical conversion layer may contain components other than the resin, such as silica particles, Nb compounds, and phosphoric acid compounds, along with the resin and the yellow colorant, and the content of the resin may be the remainder of these components. Moreover, there exists an advantage that corrosion resistance is ensured by making content of resin into 99.9 mass % or less.

(yellow colorant)

A yellow colorant is contained in the conversion layer. By incorporating a yellow colorant into the converted layer, the converted layer is colored yellow, and the appearance of the Zn-based plating layer exhibits a golden color in addition to the metallic luster of the Zn-based plating layer. In order to acquire this effect, it is preferable to make content of the yellow colorant in the conversion process layer into the range of 0.1-10 mass %. By setting the content of the yellow colorant in the converted layer to 0.1% by mass or more, the appearance of the Zn-based plating layer can be made golden. Further, by setting the content of the yellow colorant to 10% by mass or less, the metallic luster of the Zn-based plating layer is not shielded, and a golden color can be exhibited. Here, the appearance in the present invention means the appearance when the Zn-based plated steel sheet is viewed from the side of the Zn-based plating layer disposed on at least one side of the steel sheet.

As a yellow colorant, a yellow pigment is preferable. Yellow pigments have superior weatherability compared to yellow dyes. In addition, when forming the chemical conversion layer, the chemical conversion layer may be cooled by water, but yellow dye may elute from the chemical conversion layer to the cooling water, so a yellow pigment that is free from elution is preferable. As the yellow pigment, an iron oxide yellow pigment or an azo yellow pigment is preferable. These pigments are preferable because they are more excellent in weather resistance.

As a yellow pigment, a generally known and well-known thing can be used, For example, an iron oxide type yellow pigment etc. are mentioned. As the iron oxide-based yellow pigment, generally known ones such as Pigment Yellow42 can be used. For example, iron oxide pigments sold by LANXESS Corporation, Ferro Corporation, Dainichi Seika Kogyo Co., Ltd. can Moreover, you may use yellow lead etc. as a yellow colorant. Moreover, as an azo yellow pigment, you may use an acetoacetic acid arylide type monoazo pigment, an acetoacetic acid arylide type disazo pigment, a condensed azo pigment, a benzimidazolone type monoazo pigment, etc.

When the pigment in the chemical conversion layer is an iron oxide-based yellow pigment, the content is measured by the following method. First, a thin film sample of the converted layer is prepared by a microtome method so that a cross section perpendicular to the rolling direction of the Zn-based plated steel sheet of the present embodiment can be observed. 200 kV field emission transmission electron microscope (FE-TEM) in an area of 20 μm × t μm (20 μm in the direction parallel to the plate width direction and t μm in the film thickness direction) of the obtained thin film sample At least 5 regions are observed at a magnification of 100,000 times using an energy dispersive X-ray analyzer (EDS or EDX), and elemental mapping is performed. From the result of elemental mapping, the area ratio of the region where Fe is present is determined. Here, by the method similar to the above, the area ratio of the region in which Fe exists in a plurality of comparative samples having a chemical conversion layer having a known pigment content is obtained, and a calibration curve is drawn in advance from the relationship with the pigment content. Have it ready. The content of the pigment of the target sample is determined using the calibration curve.

(Metal Oxide Particles)

Here, the yellow colorant colors the converted layer yellow so that the appearance of the Zn-based plating layer looks golden. However, if the converted layer contains a yellow colorant, the corrosion resistance of the converted layer may decrease. Therefore, in order to prevent a decrease in the corrosion resistance of the converted layer, metal oxide particles may be contained in the converted layer of the present embodiment. As the metal oxide particles, those having an average particle diameter in the range of 5 to 200 nm are suitable. Metal oxide particles with an average particle diameter of less than 5 nm are difficult to obtain, and a chemical conversion layer containing metal oxide particles with an average particle diameter of less than 5 nm is actually difficult to fabricate and manufacture. The lower limit is 5 nm or more. In addition, when the average particle diameter of the metal oxide particles is 200 nm or less, the converted layer does not become cloudy and the metallic appearance of the Zn-based plating layer is not damaged. By incorporating metal oxide particles of an appropriate average particle diameter, light is slightly diffusely reflected in the converted layer, so that the fluctuation of light reflection can be suppressed by effects such as making minute flaws on the plating surface less conspicuous. , can give the golden color a sense of luxury. Therefore, as for the average particle diameter of a metal oxide particle, 5-50 nm is more preferable.

The metal oxide particles preferably have a refractive index of 1.3 to 2.5 from the viewpoint of appropriately controlling diffused reflection of light within the converted layer. The refractive index is measured by isolating metal oxide particles from the converted layer and using a commercially available refractive index measuring device.

It is preferable to contain metal oxide particles in a ratio of 1 to 20% by mass in the converted layer. When the content of the metal oxide particles is 1% by mass or more, the effect of improving corrosion resistance is obtained. In addition, by setting the content of the metal oxide particles to 20% by mass or less, the converted layer itself does not become brittle, and the Zn-based plating layer can be coated stably. The content of the metal oxide particles is more preferably 3 to 7% by mass in the chemical conversion layer from the viewpoint of appropriately controlling diffused reflection of light.

In general, since inorganic pigments such as metal oxide particles have a small particle size, they may exist in the converted layer in the form of secondary particles having a larger particle size than the primary particle size. The particle size of these secondary particles (particles in which inorganic pigments are agglomerated) is hereinafter referred to as "secondary particle size". The metal oxide particles in the present embodiment may have primary particles and secondary particles mixed, and even if primary particles and secondary particles are mixed, the average particle diameter may be in the range of 5 to 200 nm. .

The average particle diameter of the metal oxide particles in the converted layer is measured by the following method. First, a thin film sample of the converted layer is prepared by a microtome method so that a cross section perpendicular to the rolling direction of the steel sheet of the present invention can be observed. 200 kV field emission transmission electron microscope (FE-TEM) in an area of 20 μm × t μm (20 μm in the direction parallel to the plate width direction and t μm in the film thickness direction) of the obtained thin film sample Observe at least 5 areas at 100,000x magnification using Using Formula 4 below, the equivalent circle diameter of all the silica particles in the observation area is calculated, and the average particle diameter is obtained by averaging the equivalent circle diameter as the particle diameter of each metal oxide particle.

Circle equivalent diameter=2√(S/π) … Equation 4

However, S is the area of the metal oxide particle, and π is the circumference ratio.

The content of metal oxide particles in the converted layer is measured by the following method. First, apart from the sample of interest, a plurality of comparative samples having a chemical conversion layer having a known content of metal oxide particles were prepared, and the surfaces of these samples were measured with a fluorescent X-ray apparatus, and the obtained detection intensities of metal elements and metal oxides were measured. A calibration curve is drawn from the relationship between the particle content. Next, the target sample is measured with a fluorescent X-ray apparatus under the same conditions as the comparative sample, and the metal oxide particle content is determined from the obtained metal element detection intensity using the calibration curve.

In the present invention, since the average particle diameter in the state of the water-dispersed metal oxide particles before being dispersed in the paint is maintained even in the converted layer, that value may be used as the average particle diameter.

The mixing ratio of the metal oxide particles and the yellow colorant is preferably optimized. That is, the mixing ratio (mass ratio (metal oxide particles/yellow colorant)) of the metal oxide particles and the yellow colorant in the converted layer is preferably in the range of 1 to 200. By setting the mixing ratio to 1 or more, even when the converted layer contains a yellow colorant, the corrosion resistance of the converted layer can be improved. Further, by setting the mixing ratio to 200 or less, deterioration in the appearance of the Zn-based plating layer can be prevented.

It is more preferable that the metal oxide particles contain silica particles from the viewpoint of ensuring a balance between corrosion resistance and a luxurious golden appearance. Further, as the metal oxide particles, titania particles, alumina particles, zirconia particles, and the like, which have effects similar to those of the silica particles, may be contained.

The chemical conversion layer may further contain either or both of a Nb compound and a phosphoric acid compound. When a Nb compound or a phosphoric acid compound is contained, the corrosion resistance of the Zn-based plating layer is improved.

As the Nb compound, conventionally known niobium-containing compounds can be used, and examples thereof include niobium oxide, niobic acid and salts thereof, fluoroniobate, and fluorooxoniobate. Especially, it is preferable to use niobium oxide from the point of improvement of corrosion resistance.

As a phosphoric acid compound, For example, phosphoric acids, such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, and their salts; Phosphonic acids and their salt; organic phosphoric acids such as phytic acid and salts thereof; and the like. The cationic species of the salt is not particularly limited, and examples thereof include Cu, Co, Fe, Mn, Sn, V, Mg, Ba, Al, Ca, Sr, Nb, Y, Ni, and Zn. These may be used independently and may use 2 or more types together.

The Nb compound and the phosphoric acid compound may be contained in a total amount of 0.5 to 30% by mass in the chemical conversion layer. When the content of the Nb compound or phosphoric acid compound is 0.5% by mass or more, the effect of improving corrosion resistance is obtained, and when the content of the Nb compound or phosphoric acid compound is 30% by mass or less, the converted layer does not become brittle and the Zn-based plating layer is stably coated. can do.

In addition, the deposition amount of the chemical conversion layer per side of the Zn-based plating layer is 0.1 to 15 g/m 2 . When the deposition amount is 0.1 g/m 2 or more, the conversion treatment layer has a sufficient adhesion amount, so that the appearance of the Zn-based plating layer can be made golden, and the corrosion resistance of the Zn-based plating layer can be improved. In addition, if the deposition amount is 15 g/m or less, even if the converted layer contains a yellow colorant, reflection of light on the surface of the converted layer is reduced, the metallic luster of the surface of the Zn-based plating layer is not shielded, and the Zn-based plating layer The exterior of the can be gold. A more preferable adhesion amount is 0.2 to 2 g/m 2 . Moreover, it is more preferable that the thickness of the conversion process layer is 0.07-15 micrometers corresponding to the said adhesion amount.

The chemical conversion layer may further contain at least one crosslinking agent selected from the group consisting of a silane coupling agent, a crosslinkable zirconium compound, and a crosslinkable titanium compound. These may be used independently and may use 2 or more types together.

When at least one crosslinking agent selected from the group consisting of the above silane coupling agent, crosslinkable zirconium compound and crosslinkable titanium compound is contained, the adhesion between the Zn-based plating layer and the chemical conversion treatment layer is further improved.

The silane coupling agent is not particularly limited, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylethoxysilane, and N-[2- (vinylbenzylamino)ethyl] -3-aminopropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, 2-(3,4 -Epoxycyclohexyl)ethyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, N-β-( Aminoethyl)-(gamma)-aminopropyl methyl dimethoxysilane, N-phenyl-(gamma)-aminopropyl trimethoxysilane, (gamma)-mercaptopropyl tritrimethoxysilane, etc. are mentioned. The said silane coupling agent may be used independently and may use 2 or more types together.

The crosslinkable zirconium compound is not particularly limited as long as it is a zirconium-containing compound having a plurality of functional groups capable of reacting with a carboxyl group or a hydroxyl group, but is preferably a compound soluble in water or an organic solvent, and more preferably a water-soluble zirconium compound do. Examples of such a compound include zirconyl ammonium carbonate.

The crosslinkable titanium compound is not particularly limited as long as it is a titanium-containing compound having a plurality of functional groups capable of reacting with carboxyl groups or hydroxyl groups, but dipropoxybis(triethanolaminato)titanium, dipropoxybis(diethanolaminato) ) Titanium, propoxy tris (diethanol aminato) titanium, dibutoxy bis (triethanol aminato) titanium, dibutoxy bis (diethanol aminato) titanium, dipropoxy bis (acetylacetonato) titanium, Dibutoxy bis(acetylacetonato)titanium, dihydroxy bis(lactato)titanium monoammonium salt, dihydroxy bis(lactato)titanium diammonium salt, propanedioxytitanium bis(ethylacetoacetate), oxotitanium Bis (monoammonium oxalate), isopropyl tri(N-amide ethyl aminoethyl) titanate, etc. are mentioned. The said crosslinking agent may be used independently and may use 2 or more types together.

It is preferable to contain 0.1-50 mass % of at least 1 sort(s) of crosslinking agent selected from the group which consists of the said silane coupling agent, a crosslinkable zirconium compound, and a crosslinkable titanium compound with respect to 100 mass% of solid content of resin. When content of this crosslinking agent is less than 0.1 mass %, the adhesive improvement effect may not be acquired, and when content of this crosslinking agent exceeds 50 mass %, stability of an aqueous composition may fall.

The conversion layer may further contain at least one crosslinking agent selected from the group consisting of amino resins, polyisocyanate compounds, blocks thereof, epoxy compounds, and carbodiimide compounds. These crosslinking agents may be used independently or may use 2 or more types together.

When at least one crosslinking agent selected from the group consisting of amino resins, polyisocyanate compounds, blocks thereof, epoxy compounds and carbodiimide compounds is contained, the crosslinking density increases, the barrier properties of the converted layer are improved, and corrosion resistance is improved. further improve

It does not specifically limit as said amino resin, For example, a melamine resin, benzoguanamine resin, urea resin, glycoluril resin, etc. are mentioned.

The polyisocyanate compound is not particularly limited, and examples thereof include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and tolylene diisocyanate. Moreover, the block material is the block material of the said polyisocyanate compound.

The epoxy compound is not particularly limited as long as it is a compound having a plurality of oxirane rings, and examples thereof include adipic acid diglycidyl ester, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, and sorbitan polyglycidyl ester. Dill ether, pentaerythritol polyglycidyl ether, glycerin polyglycidyl ether, trimethylpropane polyglycidyl ether, neopentyl glycol polyglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl Ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 2,2-bis-(4'-glycidyloxyphenyl)propane, tris(2,3-epoxypropyl)isocyanurate , bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and the like.

As the carbodiimide compound, for example, after synthesizing an isocyanate-terminated polycarbodiimide by a condensation reaction involving diisocyanate compounds such as aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate with decarbonization, further isocyanate and compounds to which a hydrophilic segment having a functional group having reactivity with a group is added.

It is preferable to contain 0.1-50 mass % of at least 1 sort(s) of crosslinking agent selected from the group which consists of the said amino resin, polyisocyanate compound, its block body, an epoxy compound, and a carbodiimide compound with respect to 100 mass % of solid content of resin. In the case of less than 0.1% by mass, the effect of improving corrosion resistance may not be obtained because the content is small, and in an amount exceeding 50% by mass, the converted layer may become brittle and the corrosion resistance may decrease.

It is preferable to further contain at least one selected from the group consisting of vanadium compounds, tungsten compounds and molybdenum compounds in the converted layer. These may be used independently and may use 2 or more types together.

Corrosion resistance of the converted layer is improved by containing at least one selected from the group consisting of the vanadium compound, tungsten compound and molybdenum compound.

The vanadium compound is not particularly limited, and conventionally known vanadium-containing compounds can be used. For example, vanadium acid and vanadate salts such as ammonium vanadate and sodium vanadate; phosphorus such as vanadium acid and ammonium vanadate; A vanadate etc. are mentioned.

The tungsten compound is not particularly limited, and conventionally known tungsten-containing compounds can be used. For example, tungstates such as tungstic acid and ammonium tungstate, sodium tungstate, phosphorus such as tungstic acid and ammonium tungstate A tungstate etc. are mentioned.

The molybdenum compound is not particularly limited, and conventionally known molybdenum-containing compounds can be used, such as molybdenum salts. The molybdate is not limited in its skeleton and degree of condensation, and examples thereof include orthomolybdate, paramolybdate and metamolybdate. Moreover, all salts, such as a single salt and a double salt, are included, and a phosphate molybdate etc. are mentioned as a double salt.

It is preferable to contain 0.01-20 mass % of at least 1 sort(s) selected from the group which consists of the said vanadium compound, a tungsten compound, and a molybdenum compound with respect to 100 mass % of solid content of resin. When the content of at least one selected from the group consisting of the vanadium compound, tungsten compound, and molybdenum compound is less than 0.01% by mass, the effect of improving corrosion resistance may not be obtained, and the vanadium compound, tungsten compound, and molybdenum compound When the content of at least one selected from the group exceeds 20% by mass, the converted layer may become brittle and the corrosion resistance may decrease.

The chemical conversion layer may further contain a polyphenol compound.

By containing the polyphenol compound, the corrosion resistance of the chemical conversion treatment layer and the adhesion of the post-coating film when used for post-coating applications and the like are improved.

The said polyphenol compound is a compound or its condensate which has two or more phenolic hydroxyl groups couple|bonded with the benzene ring. As a compound which has two or more phenolic hydroxyl groups couple|bonded with the said benzene ring, gallic acid, pyrogallol, catechol, etc. are mentioned, for example. The condensate of a compound having two or more phenolic hydroxyl groups bonded to a benzene ring is not particularly limited, and examples thereof include polyphenol compounds commonly known as tannic acids and widely distributed in the plant kingdom. Tannic acid is a general term for aromatic compounds with a complex structure having many phenolic hydroxyl groups widely distributed in the plant kingdom. The tannic acid may be hydrolysable tannic acid or condensed tannic acid. The tannic acid is not particularly limited, and examples thereof include hamameli tannins, persimmon tannins, tea tannins, nut gall tannins, gall tannins, myrobalan tannins, dividvi tannins, agarobilla tannins, valonia tannins, catechin tannins, and the like. can be heard

As the tannic acid, those commercially available, for example, "tannic acid extract A", "B tannic acid", "N tannic acid", "common tannic acid", "purified tannic acid", "Hi tannic acid", "F tannic acid" ", "Koku Tannic Acid" (both manufactured by Dainippon Seiyaku Co., Ltd.), "Tannic Acid: AL" (manufactured by Fuji Chemical Industry Co., Ltd.), and the like can also be used. The said polyphenol compound may be used independently and may use 2 or more types together.

It is preferable to contain 0.1-50 mass % of the said polyphenol compound with respect to 100 mass % of solid content of resin. When the content of the polyphenol compound is less than 0.1% by mass, the effect of improving corrosion resistance may not be obtained, and when the content of the polyphenol compound exceeds 50% by mass, the stability of the aqueous composition may decrease.

The conversion layer may further contain a solid lubricant.

By containing the solid lubricant, the lubricity of the converted layer is improved, and it is effective for improving workability during press molding, preventing scratches caused by molds and handling, and preventing wear and tear during transportation of molded products and coils.

The solid lubricant is not particularly limited, and includes known fluorine-based, hydrocarbon-based, fatty acid amide-based, ester-based, alcohol-based, metal soap-based and inorganic lubricants. As a criterion for selecting a lubricating additive for improving workability, selecting a substance present on the surface of the converted layer rather than dispersing the added lubricant in the converted layer formed into a film reduces friction between the surface of the molded product and the mold. This is necessary in order to maximize the lubrication effect. That is, when the lubricant is dispersed and present in the converted layer formed into a film, the surface friction coefficient is high, so the converted layer is easily destroyed, and powdery substances are exfoliated and deposited, resulting in poor appearance and reduced workability called a powdering phenomenon. As the substance present on the surface of the converted layer, a substance incompatible with resin and having a small surface energy is selected.

It is preferable to contain 0.1-30 mass % of the said solid lubricant with respect to 100 mass % of solid content of resin. When the content of the solid lubricant is less than 0.1%, the workability improvement effect is small, and when the content of the solid lubricant exceeds 30%, the corrosion resistance may decrease.

A method of coating an aqueous composition used for formation of the chemical conversion layer is to apply the aqueous composition to the surface of the Zn-based plating layer to form a film. The coating method is not particularly limited, and generally used roll coating, air spray, airless spray, dipping or the like can be appropriately employed. In order to increase the curability of the converted layer, it is preferable to heat the coated object in advance or heat-dry the coated object after coating. As a heat drying method, any method of hot air, induction heating, near infrared, far infrared, etc. may be sufficient, and you may use it together. The heating temperature of the object to be coated is 50 to 250°C, preferably 70 to 220°C. When the heating temperature is less than 50°C, the rate of evaporation of moisture is slow and sufficient film-forming properties cannot be obtained, so corrosion resistance may decrease. On the other hand, when the heating temperature exceeds 250 ° C., thermal decomposition of the resin occurs and corrosion resistance is lowered, and the appearance is deteriorated due to yellowing or the like. The drying time in the case of heat drying after coating is preferably 1 second to 5 minutes. In addition, in the case of heat drying, in the case of manufacturing with a continuous line from a viewpoint of productivity, it is preferable to carry out water cooling.

The arithmetic mean height Sa of the converted layer is preferably 5 nm to 100 nm. When the arithmetic mean height Sa of the converted layer is 100 nm or less, the transmittance of the converted layer can be maintained. On the other hand, when Sa exceeds 100 nm, there is a possibility that the transmittance of the converted layer may decrease. The arithmetic mean height Sa of the converted layer is measured and calculated by the following method. Gold is deposited on the surface of a sample cut to a predetermined size from a Zn-based plated steel sheet to a thickness of 50 nm, the gold-deposited sample is embedded in a resin, and polished so that the cross section of the sample in the plate thickness direction is exposed. The arithmetic average height Sa of the converted layer is obtained by observing the cross section of the sample at a magnification of 5000 times using a scanning electron microscope and calculating the roughness of the gold deposited layer when observed from the direction perpendicular to the cross section. Gold deposition is performed to clarify the boundary between the converted layer and the resin, and since the thickness of the gold deposited layer is negligible compared to the converted layer, the arithmetic mean height of the gold deposited layer is the height of the surface of the converted layer. It can be substituted as the arithmetic mean height Sa.

[Exterior]

Next, the appearance of the Zn-based plated steel sheet of the present embodiment will be described. As for the appearance of the Zn-based coated steel sheet of the present embodiment, when evaluated in the CIE1976 (L*, a*, b*) color space, b* is 2 or more and 60 or less, and b*/a* is -3 or more and 3 or less. , and the 60-degree mirror gloss G _s (60°) specified in JIS Z 8741: 1997 is 50 to 200. Further, in a plane orthogonal to the surface of the converted layer, light is incident toward the surface of the converted layer from an angle of 60° from the surface of the converted layer, and the light reflected from the surface of the converted layer is transmitted to the converted layer. L* obtained when light is received at an angle of 135° from the surface of is referred to as L*1, and light is incident toward the surface of the converted layer from an angle of 120° from the surface of the converted layer in the above plane, When L* obtained when light reflected from the surface of the conversion layer is received at an angle of 135° from the surface of the conversion layer is L*2, L*1 and L*2 satisfy Equation 1 below .

10≥L*1/L*2≥2 ... Equation 1

The reasons for these limitations will be explained below.

The more light is reflected from the surface of the Zn-based plating layer, the higher the light luminance, and when it is low, the reflection from the conversion treatment layer increases. Therefore, the appearance of the Zn-based plating layer does not show a gold color. Therefore, in order to obtain the synergistic effect of the Zn-based plating layer exhibiting metallic luster and the conversion treatment layer colored yellow by the yellow colorant, b* and b*/a* and 60 degree mirror gloss G _s (60°) It has been found that it is necessary to make L*1 and L*2 satisfy 10≧L*1/L*2≧2 (Equation 1) within a predetermined range.

When b* in the case of evaluation in the CIE1976 (L*, a*, b*) color space becomes less than 2, the color almost disappears and the gold color is not displayed. Further, when b* exceeds 60, the color becomes dark, and the metallic appearance is not sufficiently recognized, so that the gold color is not displayed. Therefore, b* is set within the range of 2 or more and 60 or less. The lower limit of b* is preferably 3.5, and more preferably 5, from the viewpoint of maintaining the golden color. The upper limit of b* is preferably 40, and more preferably 30, from the viewpoint of maintaining the metallic appearance.

When b*/a* at the time of evaluation in the CIE1976 (L*, a*, b*) color space is less than -3, the yellow-red color becomes thicker, so the gold color is not displayed. In addition, when b*/a* exceeds 3, the green color becomes thicker and the gold color is not displayed. Therefore, b*/a* is set within the range of -3 or more and 3 or less.

In addition, when the 60 degree mirror gloss G _s (60 °) is less than 50, the appearance of the Zn-based coated steel sheet becomes closer to white, the metallic luster of the Zn-based coating layer is damaged, and the appearance of the Zn-based coating layer does not show a golden color. . Further, when the 60-degree mirror gloss G _s (60°) exceeds 200, the reflection on the surface of the converted layer becomes strong, and the appearance of the Zn-based plating layer becomes yellow and does not exhibit a gold color.

In addition, when L*1/L*2 is 10 or less, there is an effect of improving golden color development. When L*1/L*2 is 2 or more, there is an effect of maintaining a metallic appearance. The lower limit of L*1/L*2 is more preferably 4 from the viewpoint of maintaining a more beautiful metal appearance. As for the upper limit of L*1/L*2, 7 is more preferable from the viewpoint of developing a luxurious golden color.

In addition, for the appearance of the Zn-based plated steel sheet of the present embodiment, L* in the range of 0.5 mm in diameter centered on each point was measured at 5 arbitrary points on the plating surface excluding the surface layer coating film including the chemical conversion treatment layer. It is preferable that the maximum value of L* (L*max) at the time of carrying out is 1.2 times or more of the minimum value of L* (L*min).

When the maximum value of L* (L*max) is 1.2 times or more of the minimum value of L* (L*min), local fluctuations occur in the golden color, resulting in an effect of creating a deep sense of luxury.

With respect to the plating surface from which the surface layer coating film including the conversion treatment layer was removed with a coating film release agent (eg, Neo River SP-751 manufactured by Sansai Kako Co., Ltd.) that does not erode the plating, for five randomly selected points, microplane spectral color difference L* at each point is measured using a meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., VSS 7700). Among the measured L*, the largest one is referred to as L*max, and the smallest one is referred to as L*min.

Further, on the surface of the Zn-based plating layer according to the present embodiment, a patterned portion and a non-patterned portion arranged to have a predetermined shape may be formed.

It is preferable that the pattern portion is arranged so as to have a shape in which any one of a straight line portion, a curved portion, a dot portion, a figure, a number, a symbol, a pattern, or a character, or a combination of two or more thereof. In addition, the non-pattern part is an area other than the pattern part. In addition, the shape of the pattern portion is acceptable as long as it can be recognized as a whole even if a part of it is missing, such as missing dots. Further, the non-pattern portion may have a shape forming a border and an edge of the pattern portion.

When any one of straight lines, curved parts, dot parts, figures, numbers, symbols, patterns, or characters, or a combination of two or more of these are disposed on the surface of the Zn-based plating layer, these areas are called pattern parts. And, the area other than that can be referred to as a non-pattern portion. The boundary between the pattern portion and the non-pattern portion can be grasped visually. The boundary between the pattern portion and the non-pattern portion may be grasped from an enlarged image by an optical microscope or a magnifying glass.

The pattern portion may be formed in a size capable of discriminating the presence of the pattern portion with the naked eye, under a magnifying glass, or under a microscope. In addition, the non-patterned portion is a region that occupies most of the Zn-based plating layer (surface of the Zn-based plating layer), and the patterned portion is sometimes disposed within the non-patterned portion.

The pattern part is arranged in a predetermined shape in the non-pattern part. Specifically, in the non-pattern portion, the pattern portion is arranged so as to have a shape in which any one type of a straight line portion, a curved portion, a figure, a dot portion, a figure, a number, a symbol, a pattern, or a character, or a combination of two or more thereof, is formed in the non-pattern portion. has been By adjusting the shape of the pattern portion, a straight line portion, a curved portion, a figure, a dot portion, a figure, a number, a symbol, a pattern, or a shape combining two or more of these appear on the surface of the Zn-based plating layer. . For example, on the surface of the Zn-based plating layer, a character string, a number string, a symbol, a mark, a diagram, a design image, or a combination thereof composed of a pattern portion appears. This shape is a shape formed intentionally or artificially by a manufacturing method described later, and is not formed naturally.

As described above, the patterned portion and the non-patterned portion are regions formed on the surface of the Zn-based plating layer, and the patterned portion and the non-patterned portion include one or two of the first region and the second region, respectively.

The pattern portion and the non-pattern portion each include one or both of the first region and the second region determined by any one of determination methods 1 to 5 below, and the area ratio of the first region in the pattern portion and the absolute value of the difference between the area ratio of the first region in the non-pattern portion is 30% or more. When the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more in absolute value, the pattern portion and the non-pattern portion can be distinguished. When the difference in this area ratio is less than 30%, the difference between the area ratio of the first region in the pattern part and the area ratio of the first region in the non-pattern part is small, and the appearances of the pattern part and the non-pattern part are similar. This makes it difficult to identify the pattern portion. The larger the difference in area ratio, the better. It is more preferable that the difference in area ratio is 40% or more, and it is more preferable that the difference in area ratio is 60% or more.

That is, in the pattern portion, the respective area ratios of the first region and the second region can be obtained. And, when the area fraction of the first region exceeds 70%, the pattern portion appears relatively white or close to white compared to the case where the area fraction of the first region is 70% or less. When the area fraction of the first region is 30% or more and 70% or less, the pattern portion looks like a pear skin pattern. Further, when the area fraction of the first region is less than 30%, the pattern portion appears metallic luster. In this way, the appearance of the pattern portion depends on the area fraction of the first region.

On the other hand, even in the non-pattern portion, the respective area ratios of the first area and the second area can be obtained. Like the patterned portion, the appearance of the non-patterned portion depends on the area fraction of the first region.

Then, when the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more in absolute value, the pattern portion and the non-pattern portion can be distinguished. When the difference in this area ratio is less than 30%, the difference between the area ratio of the first region in the pattern part and the area ratio of the first region in the non-pattern part is small, and the appearances of the pattern part and the non-pattern part are similar. This makes it difficult to identify the pattern portion. The larger the difference in area ratio, the better, more preferably 40% or more, and still more preferably 60% or more.

[Decision method 1]

In determination method 1, virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and in a plurality of areas partitioned by the virtual lattice lines, respectively, within a circle with a diameter of 0.5 mm centered on the center of gravity of each area. is set as measurement area A, and the L* value in each measurement area A is measured. When 50 points are randomly selected from the obtained L* values and the average of 50 points of the obtained L* values is referred to as the reference L* value, the region in which the L* value is equal to or greater than the reference L* value is the first region, the reference L An area that is less than the * value is referred to as a second area.

[Decision method 2]

In determination method 2, virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and in a plurality of regions partitioned by the virtual lattice lines, respectively, within a circle with a diameter of 0.5 mm centered on the center of gravity of each region. is defined as a measurement region A, the L* value in each measurement region A is measured, the region in which the L* value is 45 or more is referred to as a first region, and the region in which the L* value is less than 45 is referred to as a second region. .

[Decision method 3]

In determination method 3, virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and the arithmetic average surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual lattice lines. A region in which the obtained Sa is 1 μm or more is referred to as a first region, and a region in which Sa is less than 1 μm is referred to as a second region. The measurement of the arithmetic mean surface roughness Sa is performed using a 3D laser microscope (manufactured by Keyence Corporation). In the present embodiment, the height Z within the region is measured at a measurement interval of 50 µm, respectively, in a plurality of regions partitioned by virtual grid lines using a 20x standard lens. In the case of measurement on a grid, 100 measurement points are obtained within the area. The arithmetic mean surface roughness Sa is calculated by Equation 5 below using the obtained height Z 100 points from the height Z1 to the height Z100. Zave is the average of 100 height Z points.

Sa=1/100×Σ[x=1→100] (|Height Zx-Zave|) ... Equation 5

[Decision method 4]

In determination method 4, by an X-ray diffraction method in which virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 1 mm or 10 mm, and X-rays are respectively incident on a plurality of regions partitioned by the virtual lattice lines, For each region, the diffraction peak intensity I ₀₀₀₂ of the (0002) plane of the Zn phase and the diffraction peak intensity I _10-11 of the (10-11) plane of the Zn phase are measured, and these intensity ratios (I ₀₀₀₂ /I _10-11 ) are obtained. is called the orientation ratio. A region having an orientation ratio of 3.5 or more is referred to as a first region, and a region having an orientation ratio of less than 3.5 is referred to as a second region.

[Decision method 5]

In determination method 5, virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 1 mm, and then, for each of a plurality of areas partitioned by the virtual lattice lines, a circle S centered on the center point G of each area is drawn. The diameter R of the circle S is set so that the total length of the surface boundary lines of the Zn-based plating layer included inside the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin among the diameters R of the circles S of the plurality of regions is referred to as the reference diameter Rave, and the region having the circle S having the diameter R less than the reference diameter Rave is referred to as the first region, and the diameter R is A region having a circle S equal to or larger than the reference diameter Rave is referred to as a second region.

The formation of the patterned portion and the non-patterned portion specified by the determination method 1 or 2 is performed after the formation of the Zn-based plating layer. The formation of the patterned portion and the non-patterned portion is performed by adhering an acidic solution to the surface of the Zn-based plating layer at 60 to 200°C. More specifically, an acidic solution may be prepared, and this may be adhered to the surface of the Zn-based plating layer by a printing means. As the printing means, general printing methods such as printing methods using various plates (gravure printing, flexographic printing, offset printing, silk printing, etc.) and inkjet printing methods can be applied.

At the location where the acidic solution adhered, the surface of the Zn-based plating layer is dissolved, and the surface of the Zn-based plating layer is changed from the plated state. As a result, the appearance of the location to which the acidic solution has adhered is changed in comparison with the location to which the acidic solution has not adhered. In this way, it is estimated that the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion increases, and the pattern portion and the non-pattern portion can be distinguished.

The adhesion range of the acidic solution may be a region corresponding to the patterned portion or a region corresponding to the non-patterned portion.

As the acidic solution, it is preferable to use an inorganic acid such as hydrochloric acid, nitric acid, or sulfuric acid. Moreover, it is preferable that the concentration of the acid in an acidic solution is 0.1-10 mass %. The steel sheet temperature at the time of adhesion of the acidic solution is preferably 60 to 200°C, preferably 50 to 80°C. By adjusting the type and concentration of the acidic solution, it is possible to adjust the area fraction of the first region and the second region on the surface of the Zn-based plating layer at the site where the acidic solution is deposited.

If the surface temperature of the Zn-based plating layer at the time of adhering the acidic solution is less than 60°C, it is not preferable because it takes time to form the patterned portion or the non-patterned portion, and if the surface temperature of the Zn-based plating layer exceeds 200°C, acid This is not preferable because the solution immediately volatilizes, making it impossible to form a patterned portion or a non-patterned portion.

After the acidic solution has adhered, it is necessary to wash with water within 1 to 10 seconds.

Next, formation of the patterned portion and non-patterned portion specified by the determination method 3 is performed after the formation of the Zn-based plating layer. The formation of the pattern portion and the non-pattern portion is performed by pressing a roll whose surface roughness is partially increased to the surface of the Zn-based plating layer, and transferring the surface shape of the roll to the Zn-based plating layer. For example, in order to form the pattern portion on the surface of the Zn-based plating layer, the roughness of the portion corresponding to the pattern portion on the surface of the roll is increased relative to the other portions, and the pattern portion including many first regions having large surface roughness. can be formed. Conversely, you may use the roll which made the roughness of the location corresponding to a pattern part small with respect to another location. The roughness (arithmetic average surface roughness, Sa (μm)) of the roll surface is set to be 0.6 to 3.0 μm, preferably 1.2 to 3.0 μm, in a location where the roughness is increased. The range of the roughness in the location where the roughness is low is 0.05 to 1.0 µm, preferably 0.05 to 0.8 µm. The transfer may be performed when the surface temperature of the Zn-based plating layer is in the range of 100 to 300°C. In addition, the difference between the roughness at a location where the roughness is increased and the roughness at a location where the roughness is low is set to be more than 0.2 μm, preferably 0.3 μm or more, in terms of arithmetic mean surface roughness Sa. When the difference in illuminance becomes small, it becomes difficult to discriminate a pattern part and a non-pattern part.

The formation of the patterned portion and non-patterned portion specified by the determination method 4 is performed by locally spraying a non-oxidizing gas to the metal in a molten state using a gas nozzle on the steel sheet immediately after being pulled out of the molten plating bath. As the non-oxidizing gas, nitrogen or argon may be used. Although the optimal temperature range differs depending on the composition, the non-oxidizing gas may be sprayed when the temperature of the molten metal is in the range of (final solidification temperature -5) °C to (final solidification temperature +5) °C. In addition, the temperature of the non-oxidizing gas is set below the final solidification temperature.

When the Zn-based plating layer is within the above temperature range, the cooling rate of the molten metal increases at the location where the non-oxidizing gas is blown, thereby increasing the orientation ratio of the Zn-based plating layer after solidification. On the other hand, in a location where the non-oxidizing gas is not blown, the cooling rate of the molten metal is lowered, and as a result, the orientation ratio of the Zn-based plating layer after solidification is lowered. Therefore, by adjusting the injection range of the non-oxidizing gas, it is possible to intentionally or arbitrarily adjust the respective appearance locations of regions with a high orientation ratio and regions with a low orientation ratio.

This makes it possible to arbitrarily adjust the shapes of the patterned portion and the non-patterned portion, and also to distinguish the patterned portion and the non-patterned portion. Since the orientation ratio becomes higher as the temperature of the gas to be injected is lower, the orientation ratio can be adjusted by the temperature of the gas to be injected. The gas temperature is preferably less than the final solidification temperature, and the gas temperature may be adjusted to, for example, 25 to 250°C.

Formation of the patterned portion and the non-patterned portion specified by determination method 5 is carried out by locally applying a non-oxidizing gas at or above the final solidification temperature of plating to the metal in a molten state by means of a gas nozzle, with respect to the steel sheet immediately after being raised from the molten plating bath. It is done by spraying. As the non-oxidizing gas, nitrogen or argon may be used. Although the optimal temperature range differs depending on the composition, the non-oxidizing gas may be sprayed when the temperature of the molten metal is in the range of (final solidification temperature -5) °C to (final solidification temperature +5) °C. In addition, the temperature of the non-oxidizing gas is preferably equal to or higher than the final solidification temperature. For example, in a plating composition of 11% Al and 3% Mg, when the temperature of the molten metal is 330 to 340°C, the non-oxidizing gas having a gas temperature equal to or higher than the final solidification temperature may be sprayed.

In the vicinity where the non-oxidizing gas is blown, the cooling rate of the molten metal is lowered, and as a result, the boundary or grain boundary appearing on the surface becomes coarse. Therefore, by adjusting the injection amount and range of the non-oxidizing gas, it is possible to arbitrarily adjust the size of the boundary or grain boundary appearing on the surface.

By setting the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion to 30% or more, the pattern portion and the non-pattern portion can be distinguished. Since the formed pattern portion and non-pattern portion are not formed by printing or painting, durability is high. In addition, since the patterned portion and the non-patterned portion are not formed by printing or painting, there is no effect on the corrosion resistance of the Zn-based plating layer. Therefore, the Zn-based plated steel sheet of the present embodiment has excellent corrosion resistance.

In the Zn-based plating layer in which the pattern portion is formed, a Zn-based plated steel sheet having high durability of the pattern portion and suitable plating characteristics such as corrosion resistance can be provided. Since the pattern part can have an intentional or artificial shape, arrange the pattern part so that it has a shape of any one of straight lines, curves, dots, figures, numbers, symbols, patterns, or characters, or a combination of two or more of these. can do. As a result, various designs, trademarks, and other identification marks can be displayed on the surface of the Zn-based plating layer without printing or painting, and the source identification and design quality of the steel sheet can be improved. In addition, information required for process management, inventory management, etc., or arbitrary information requested by the consumer can be provided to the hot-dipped steel sheet by the pattern portion. This can also contribute to improving the productivity of the Zn-based plated steel sheet.

And according to the Zn-based plated steel sheet of this embodiment, since the chemical conversion layer containing the yellow colorant is formed on the Zn-based plating layer in which the pattern portion is formed, the visibility of the pattern portion can be further improved.

Example

Hereinafter, the present invention will be specifically described by examples.

First, a cold-rolled steel sheet having a thickness of 1 mm was prepared, immersed in a plating bath of each composition, and the coating weight was adjusted to 80 g/m 2 on one side by N ₂ wiping. Table 1 shows the plating composition of the obtained Zn-based plated steel sheet.

In addition, in the case of forming the pattern portion in the Zn-based plating layer, the pattern was further patterned by the method described below. The pattern portion and the non-pattern portion include one or both of the first region and the second region determined by any predetermined method among determination methods 1 to 5, respectively, and the area ratio of the first region in the pattern portion and the absolute value of the difference between the area ratio of the first region in the non-pattern portion was 40%.

<Pattern 1>

A hydrochloric acid solution was adhered to a rubber plate having convex or concave portions in a square pattern of 50 mm on each side, and the rubber plate was pressed against the surface of the Zn-based plating layer, thereby adhering the acidic solution to the steel plate to form a square pattern portion. . The surface temperature of the Zn-based plating layer of the hot-dipped steel sheet at the time of adhesion of the acidic solution was in the range of 60 to 200°C. In addition, locations other than the square-shaped pattern portion were referred to as non-pattern portions. Then, based on the determination method 2, virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and in a plurality of areas partitioned by the virtual lattice lines, each has a diameter of 0.5 centered on the center of gravity of each area. The inside of a circle of mm is defined as a measurement area A, and the L* value in each measurement area A is measured. 2 regions. This Zn-based plated steel sheet was used as Example 59.

<Pattern 2>

With the surface temperature of the Zn-based plating layer set to 100 to 300°C, a roll having a square pattern with a side of 50 mm was pressed against the surface of the Zn-based plating layer to form a pattern portion. A portion of the square pattern was referred to as a pattern portion, and a portion other than the square pattern was referred to as a non-pattern portion. Based on the determination method 3, virtual lattice lines were drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and the arithmetic average surface roughness Sa was measured in each of a plurality of regions partitioned by the virtual lattice lines. A region where the obtained Sa was 1 μm or more was defined as a first region, and a region where Sa was less than 1 μm was defined as a second region. This Zn-based plated steel sheet was used as Example 60.

<Pattern 3>

When the steel sheet is pulled up from the plating bath, when the temperature of the molten metal is in the range of (final solidification temperature -5) °C to (final solidification temperature +5) °C, the molten metal on the surface of the steel plate contains a non-oxidizing gas Nitrogen gas was injected by a gas nozzle. The gas temperature was less than the final solidification temperature. It was then cooled to completely solidify the molten metal. The injection range of the nitrogen gas was controlled so as to form a square pattern with one side measuring 50 mm. A portion of the square pattern was referred to as a pattern portion, and a portion other than the square pattern was referred to as a non-pattern portion. Based on the determination method 4, by an X-ray diffraction method in which virtual lattice lines are drawn on the surface of the Zn-based plating layer at 1 mm intervals or 10 mm intervals, and X-rays are respectively incident on a plurality of regions partitioned by the virtual lattice lines. , For each of the above regions, the diffraction peak intensity I ₀₀₀₂ of the (0002) plane of the Zn phase and the diffraction peak intensity I _10-11 of the (10-11) plane of the Zn phase were measured, and these intensity ratios (I ₀₀₀₂ /I _10-11 ) is called the orientation ratio. A region having an orientation ratio of 3.5 or more was referred to as a first region, and a region having an orientation ratio of less than 3.5 was referred to as a second region. This Zn-based plated steel sheet was used as Example 61.

<Pattern 4>

When the steel sheet is pulled up from the plating bath, when the temperature of the molten metal is in the range of (final solidification temperature -5) °C to (final solidification temperature +5) °C, the molten metal on the surface of the steel plate contains a non-oxidizing gas Nitrogen gas was injected from a gas nozzle in a heated state. The nitrogen gas injection conditions were as shown in Table 1. above the final solidification temperature. It was then cooled to completely solidify the molten metal. The injection range of the nitrogen gas was controlled so as to form a square pattern with one side measuring 50 mm. A portion of the square pattern was referred to as a pattern portion, and a portion other than the square pattern was referred to as a non-pattern portion. Then, based on the determination method 5, virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 1 mm, and then, for each of a plurality of areas partitioned by the virtual lattice lines, a circle S centered on the center of gravity point G of each area painted The diameter R of the circle S was set such that the total length of the surface boundary lines of the Zn-based plating layer included inside the circle S was 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin among the diameters R of the circles S of the plurality of regions is referred to as the reference diameter Rave, and the region having the circle S having the diameter R less than the reference diameter Rave is referred to as the first region, and the diameter R is A region having a circle S equal to or larger than the reference diameter Rave was referred to as a second region. This Zn-based plated steel sheet was used as Example 62.

Then, as needed, the Zn-based plated steel sheet was immersed in a Co sulfate solution, Fe sulfate solution, or Ni sulfate solution to deposit 1 mg/m 2 of Co, Fe, or Ni on the surface of the Zn-based plating layer. The composition of the Zn plating layer is shown in Table 3A and Table 3B.

Next, various water-based resins (urethane resin, polyester resin, olefin resin, epoxy resin, acrylic resin, phenol resin, fluororesin), metal oxide particles, and niobium oxide were applied to the surface of the Zn-based plating layer of the manufactured Zn-based coated steel sheet. , An aqueous composition containing sodium phosphate and a yellow colorant (azo yellow pigment, iron oxide yellow pigment) was applied with a bar coater to a dry coating weight of 1.5 g/m 2 , and dried in a hot air drying furnace at a reaching plate temperature of 150° C., By cooling with water, a chromate-free chemical conversion treatment layer was formed. The contents of niobium oxide and sodium phosphate were each 5%. Further, as the metal oxide particles, silica (SiO ₂ ), titania (TiO ₂ ), alumina (Al ₂ O ₃ ), and zirconia (ZrO ₂ ) were used. Moreover, in Table 2, the detail of a yellow coloring agent is shown. In Tables 4A to 5B, the composition of the conversion treatment layer and the like are shown. In the column of "Nb oxide" in Table 5A and Table 5B, the case where niobium oxide was included was set as "○", and the case where it was not contained was set as "x". In addition, in the column of "Na phosphate", the case where sodium phosphate was included was set as "○", and the case where it was not included was set as "x".

(60 degree mirror polish Gs(60°))

Using a gloss meter, the 60° gloss (%) of the surface of the Zn plating layer was measured based on the method specified in JIS Z 8741. The case where the glossiness was 50 to 200% was designated as "A", and the case where the glossiness was less than 50% was designated as "B". The results are shown in Table 6A and Table 6B.

(b*value, b*/a*)

The surface of the Zn plating layer on which the chemical conversion treatment layer was formed was measured using a spectroscopic color difference meter (SE6000 manufactured by Nippon Denshoku Kogyo Co., Ltd.). The case where b* was 2 or more and 60 or less was called "A", and the case where b* was less than 2 or more than 60 was called "B". In addition, the case where b*/a* was -3 or more and 3 or less was called "A", and the case where b*/a* was less than -10 or more than -3 was called "B". The results are shown in Table 6A and Table 6B.

(L*1/L*2)

The case where L*1/L*2 was 4 or more and 7 or less was called "A", the case where L*1/L*2 was 2 or more and less than 4, or more than 7 and less than 10 was called "B", and the case of less than 2 or more than 10 was called "C".

(corrosion resistance)

A salt spray test (JIS Z 2371:2015) was conducted on the Zn-based plated steel sheet. The state of occurrence of white rust after 24 hours of the test time of the part subjected to the Ericsson processing was observed, and the rating shown below was determined. The rating set 3 or more as the pass. Results are shown in Table 6A and Table 6B.

4: Less than 5% of occurrence of white rust

3: White rust generation 5% or more and less than 10%

2: Occurrence of white rust 10% or more and less than 30%

1: 30% or more of white rust

(gold exterior)

When the surface of the Zn-plated layer of the Zn-based plated steel sheet was shown to five panelists, it was judged by how it looked golden. Evaluation was determined by rating given below, and a rating of 3 or higher was regarded as a pass. The results are shown in Table 6A and Table 6B.

5: More than 4 out of 5 people could recognize it as gold, and felt that there was no change in light reflection and that it had a sense of quality.

4: More than 4 out of 5 people could recognize it as gold, and felt that there was no change in light reflection.

3: 3 out of 5 people could recognize it as gold.

2: 2 out of 5 people could recognize it as gold.

1: Less than 1 in 5 people could perceive it as gold.

As shown in Tables 1 to 6B, all of the Zn-based plated steel sheets of Examples 1 to 71 had a conversion treatment layer that satisfied the scope of the present invention, and had good corrosion resistance and good gold appearance.

Moreover, about Examples 59-62 in which the pattern part was formed in the plating layer, while corrosion resistance and a golden appearance were favorable, the visibility of the pattern part improved significantly. In some examples, the amount of the conversion layer was applied in the range of 0.1 to 15.0 g/m 2 , but the results were good.

On the other hand, as shown in Tables 1 to 6B, in Comparative Example 1, since the converted layer did not contain resin, the converted layer itself became very brittle, and various evaluation tests could not be performed.

In Comparative Example 2, since the converted layer did not contain a yellow colorant, the b* value and b*/a* were out of the range of the present invention, and the gold appearance was insufficient.

In Comparative Examples 3, 4, and 5, Cu phthalocyanine, Co phthalocyanine, and quinacridone were contained in the converted layer, respectively, and these were not yellow colorants according to the present invention, that is, Comparative Examples 3 to 5 did not contain yellow colorants. Therefore, at least one of the b* value and b*/a* was out of the range of the present invention, and the gold appearance was insufficient.

In Comparative Examples 6 and 7, since the coating amount of the converted layer was outside the range of 0.1 to 15.0 g/m 2 , the b* value or the 60-degree mirror gloss Gs (60°) was out of the range of the present invention, and L*1/ L*2 was out of the scope of the present invention, and the golden appearance was insufficient.

[Table 1]

[Table 2]

[Table 3A]

[Table 3B]

[Table 4A]

[Table 4B]

[Table 4C]

[Table 5A]

[Table 5B]

[Table 6A]

[Table 6B]

According to the present invention, in the Zn-based coated steel sheet containing Al, since it is possible to provide a Zn-based coated steel sheet exhibiting a high-quality golden appearance and having improved corrosion resistance, the present invention has industrial applicability. is high

Claims (17)

steel plate,
a Zn-based plating layer containing 0.05 to 60% by mass of Al and Zn disposed on at least one side of the steel sheet;
At least one chromate-free chemical conversion treatment layer is provided on the Zn-based plating layer and has an adhesion amount of 0.1 to 15 g / m 2 per side,
The conversion layer contains a resin and a yellow colorant,
When the appearance is evaluated in the CIE1976 (L*, a*, b*) color space, b* is 2 or more and 60 or less, and b*/a* is -3 or more and 3 or less, and is specified in JIS Z 8741:1997. 60 degree mirror gloss G _s (60 °) is 50 to 200;
In a plane orthogonal to the surface of the converted layer, L obtained when light is incident toward the surface from an angle of 60° from the surface and light reflected from the surface is received at an angle of 135° from the surface Let * be L*1, in the plane, L obtained when light is incident toward the surface from an angle of 120° from the surface, and light reflected from the surface is received at an angle of 135° from the surface. When * is L*2, the Zn-based coated steel sheet, characterized in that the L*1 and the L*2 satisfy Equation 1 below.
10≥L*1/L*2≥2 ... Equation 1 According to claim 1,
A Zn-based plated steel sheet characterized in that the yellow colorant is an azo-based yellow pigment or an iron oxide-based yellow pigment. According to claim 1 or 2,
A Zn-based plated steel sheet characterized in that the content of the yellow colorant in the converted layer is 0.1 to 10% by mass. According to any one of claims 1 to 3,
The Zn-based plated steel sheet, characterized in that the L * 1 and the L * 2 satisfy the following formula (2).
7≥L*1/L*2≥4 ... Equation 2 According to any one of claims 1 to 4,
A Zn-based plated steel sheet characterized in that the converted layer contains 1 to 20% by mass of metal oxide particles having an average particle diameter of 5 to 200 nm and a refractive index of 1.3 to 2.5. According to claim 5,
Zn-based plated steel sheet, characterized in that the metal oxide particles include silica particles. According to claim 5 or 6,
A Zn-based plated steel sheet characterized in that a mixing ratio of the yellow colorant and the metal oxide particles in the converted layer is in the range of 1 to 200. According to any one of claims 1 to 7,
The Zn-based coated steel sheet, characterized in that the arithmetic average roughness Ra of the surface of the Zn-based plating layer is 0.1 to 2.0㎛. According to any one of claims 1 to 8,
The Zn-based plated steel sheet, characterized in that the arithmetic average roughness Ra of the Zn-based plating layer is 0.5 to 2.0 μm, and the arithmetic average height Sa of the converted layer is 5 nm to 100 nm. According to any one of claims 1 to 9,
A Zn-based plated steel sheet characterized in that the chemical conversion layer further contains either or both of a Nb compound and a phosphoric acid compound. According to any one of claims 1 to 10,
The Zn-based coated steel sheet according to claim 1, wherein the resin in the conversion layer is composed of at least one of polyolefin resin, fluororesin, acrylic resin, urethane resin, polyester resin, epoxy resin, and phenol resin. According to any one of claims 1 to 11,
The Zn-based plated layer contains, in average composition, Al: 4% by mass or more and 22% by mass or less, Mg: more than 1% by mass and 10% by mass or less, the balance being Zn and impurities. . According to any one of claims 1 to 12,
A Zn-based plated steel sheet characterized in that the Zn-based plating layer further contains Si: 0.0001 to 2% by mass in average composition. According to any one of claims 1 to 13,
A Zn-based plated steel sheet characterized in that the Zn-based plated layer further contains 0.0001 to 2% by mass of any one or two or more of Ni, Sb, and Pb in an average composition in total. According to any one of claims 1 to 14,
Zn-based, characterized in that the maximum value of L* is 1.2 times or more of the minimum value of L* when L* in the range of 0.5 mm in diameter centered on each point is measured for any 5 points on the plating surface. plated steel. According to any one of claims 1 to 15,
A pattern portion and a non-pattern portion arranged to have a predetermined shape are formed on the Zn-based plating layer,
The pattern portion and the non-pattern portion each include one or two of a first region and a second region determined by any one of determination methods 1 to 5 below,
An absolute value of a difference between an area ratio of the first region in the pattern portion and an area ratio of the first region in the non-pattern portion is 30% or more.
[Decision method 1]
Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and in a plurality of areas partitioned by the virtual lattice lines, each area is measured within a circle having a diameter of 0.5 mm centered on the center of gravity of each area. Let it be A, and measure the L* value in each measurement area|region A. When 50 points are randomly selected from the obtained L* values and the average of 50 points of the obtained L* values is referred to as the reference L* value, the region in which the L* value is equal to or greater than the reference L* value is the first region, the reference L* A region that is less than the value is referred to as a second region.
[Decision method 2]
Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and in a plurality of areas partitioned by the virtual lattice lines, each area is measured within a circle having a diameter of 0.5 mm centered on the center of gravity of each area. Denoted as A, the L* value in each measurement region A is measured, and the region in which the L* value is 45 or more is referred to as a first region, and the region in which the L* value is less than 45 is referred to as a second region.
[Decision method 3]
Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 0.5 mm, and the arithmetic average surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual lattice lines. A region in which the obtained Sa is 1 μm or more is referred to as a first region, and a region in which Sa is less than 1 μm is referred to as a second region.
[Decision method 4]
By an X-ray diffraction method in which virtual grid lines are drawn on the surface of the Zn-based plating layer at intervals of 1 mm or 10 mm, and X-rays are incident on each of a plurality of regions partitioned by the virtual grid lines, for each region, The diffraction peak intensity I ₀₀₀₂ of the (0002) plane of the Zn phase and the diffraction peak intensity I _10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I ₀₀₀₂ /I _10-11 ) is the orientation ratio It is called An area in which the orientation ratio is 3.5 or more is referred to as a first area, and an area in which the orientation ratio is less than 3.5 is referred to as a second area.
[Determination Method 5]
Virtual lattice lines are drawn on the surface of the Zn-based plating layer at intervals of 1 mm, and then, a circle S centered on the center point G of each area is drawn for each of a plurality of areas partitioned by the virtual lattice lines. The diameter R of the circle S is set so that the total length of the surface boundary lines of the Zn-based plating layer included inside the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin among the diameters R of the circles S of the plurality of regions is referred to as the reference diameter Rave, and the region having the circle S having the diameter R less than the reference diameter Rave is referred to as the first region, and the diameter R is A region having a circle S equal to or larger than the reference diameter Rave is referred to as a second region. According to any one of claims 1 to 16,
Zn-based coated steel sheet, characterized in that having any one of Co, Fe, Ni on the surface of the Zn-based plating layer.