Designed steel material

Abstract

The present invention provides a designed steel material which is capable of achieving both excellent designability, and excellent corrosion resistance and excellent weather resistance even in outdoor use. A designed steel material (1) is provided with a steel material (10), a zinc-based plating layer (20), a primer layer (30), and an organic resin layer (40). The primer layer (30) contains a binder and a first inorganic component. The organic resin layer (40) comprises a base material resin that contains a fluorine-based resin and a second inorganic component which is in the amount of 0-0.0150 g / m2 in terms of the element. The film thickness of the first inorganic component in terms of the element in the primer layer (30) is 0.0070 µm or more. The inorganic component ratio, which is the ratio of the content of the second inorganic component in terms of the element in the organic resin layer (40) to the content of the first inorganic component in terms of the element in the primer layer (30), is 0.7 or less.

Description

Design steel

[0001] The present disclosure relates to a decorative steel material, and more particularly to a decorative steel material having a zinc-based plating layer formed on the surface.

[0002] Metal materials used for outdoor building materials are required to have excellent corrosion resistance and weather resistance. Metal materials for outdoor building applications may also be required to have design properties. Stainless steel materials and aluminum alloy materials are examples of metal materials with excellent design properties. Stainless steel materials and aluminum alloy materials have excellent corrosion resistance and weather resistance. Stainless steel materials and aluminum alloy materials also have excellent texture of the metal base and excellent design properties. Therefore, these metal materials are suitable for outdoor use. However, stainless steel materials and aluminum alloy materials are expensive. Therefore, there is a demand for inexpensive metal materials for outdoor use that can replace stainless steel materials and aluminum alloy materials.

[0003] Plated steel products, which have a plating layer on their surface, have been developed as inexpensive metal materials to replace stainless steel and aluminum alloy materials. Plated steel products have moderate corrosion resistance and are therefore applicable to outdoor applications such as building materials. However, outdoor environments are more severe than indoor environments. Therefore, further improvements in the corrosion resistance and weather resistance of plated steel products are required.

[0004] Means for improving the corrosion resistance and weather resistance of plated steel materials for outdoor use have been proposed in Japanese Patent Laid-Open Publication Nos. 2012-77322 (Patent Document 1), 2012-92420 (Patent Document 2), and 2012-92421 (Patent Document 3).

[0005] In Patent Documents 1 to 3, a chemical conversion coating is formed on the plating layer of a plated steel sheet. The chemical conversion coating contains a fluorine-containing resin and a Group 4A metal compound. These documents state that by forming a chemical conversion coating containing a fluorine-containing resin and a Group 4A metal compound on the plating layer, excellent corrosion resistance and weather resistance can be obtained even outdoors.

[0006] JP 2012-77322 A JP 2012-92420 A JP 2012-92421 A

[0007] The plated steel sheets disclosed in Patent Documents 1 to 3 have excellent weather resistance and corrosion resistance even outdoors due to the chemical conversion coating described above. However, in plated steel sheets on which the chemical conversion coating described above is formed, the texture of the metal base on the surface of the plating layer is difficult to clearly see. Therefore, when a texture such as a hairline is formed on the plating layer, the texture may appear blurred or indistinct when the plated steel material is viewed outdoors, and the texture may not have a sufficient design appeal.

[0008] An object of the present disclosure is to provide a designable steel material that can achieve excellent corrosion resistance, excellent weather resistance, and excellent design even when used outdoors.

[0009] The decorative steel material of the present disclosure comprises a steel material, a zinc-based plating layer, a primer layer, and an organic resin layer. The zinc-based plating layer is formed on the surface of the steel material, and a texture is formed on the surface. The primer layer is formed on the surface of the zinc-based plating layer. The organic resin layer is formed on the surface of the primer layer. The primer layer contains a binder and a first inorganic component. The organic resin layer is formed on a base resin containing a fluorine-based resin and an organic resin layer having a thickness of 0 to 0.0150 g / m in elemental terms. ２ and a second inorganic component, wherein the first inorganic component in the primer layer has an elemental equivalent film thickness of 0.0070 μm or more, and an inorganic component ratio, which is the ratio of the elemental equivalent content of the second inorganic component in the organic resin layer to the elemental equivalent content of the first inorganic component in the primer layer, is 0.7 or less.

[0010] The decorative steel material of the present disclosure can achieve both excellent corrosion resistance and weather resistance as well as excellent design, even when used outdoors.

[0011] Fig. 1 is a cross-sectional view of the decorative steel material of this embodiment. Fig. 2 is a plan view of the surface of the zinc-based plating layer in Fig. 1. Fig. 3 is a schematic diagram showing an example of fluorine (F) and carbon (C) emission spectra obtained by glow discharge optical emission spectroscopy.

[0012] The present inventors have investigated means for achieving excellent corrosion resistance, excellent weather resistance, and excellent design even when used outdoors, based on a steel material having a textured surface formed on a zinc-based plating layer. Hereinafter, steel material having a textured surface formed on a zinc-based plating layer will also be referred to as zinc-based plated steel material.

[0013] Zinc-plated steel materials having a texture formed on the surface of a zinc-based plating layer have excellent design properties even when used outdoors. However, when a chemical conversion coating proposed in Patent Documents 1 to 3 is formed on a zinc-plated steel material having a texture formed on the surface of a zinc-based plating layer, the texture becomes less visible and appears blurred, resulting in insufficient design properties. Therefore, the present inventors investigated the causes of the deterioration in design properties. As a result, the present inventors have come to the following findings.

[0014] The chemical conversion coatings disclosed in Patent Documents 1 to 3 contain an inorganic compound (a Group 4A metal compound) in an organic resin. Inorganic compounds scatter visible light. This scattering of visible light makes it difficult to clearly see the plating surface underneath the chemical conversion coating containing the organic resin, making it appear blurry.

[0015] As mentioned above, if an organic resin contains an inorganic compound, the scattering of visible light occurs. Therefore, if the content of the inorganic compound in the organic resin is reduced as much as possible, the scattering of visible light can be suppressed. However, in this case, the corrosion resistance of the zinc-based plated steel material decreases.

[0016] Therefore, the inventors have considered dividing the coating formed on the zinc-based plating layer into a primer layer and an organic resin layer. Specifically, a primer layer is formed on the surface of the zinc-based plating layer, and an organic resin layer is formed on the surface of the primer layer. The primer layer is made to contain as many inorganic components as possible, and the content of inorganic components in the organic resin layer is minimized. In this case, light scattering caused by the inorganic components in the organic resin layer can be suppressed.

[0017] Based on the above technical concept, the present inventors have investigated the inorganic component ratio ICR, which is the ratio of the inorganic component content in the primer layer converted to elements to the inorganic component content in the organic resin layer. As a result, it has been found that the film thickness of the inorganic component (first inorganic component) in the primer layer converted to elements is set to 0.0070 μm or more, and the inorganic component content in the organic resin layer (second inorganic component) converted to elements is set to 0 to 0.0150 g / m ２ Furthermore, they have found that if the inorganic component ratio is 0.7 or less, excellent corrosion resistance and excellent weather resistance can be obtained even when used outdoors, and excellent design properties can also be obtained.

[0018] The decorative steel material of the present disclosure has been completed based on the above-mentioned technical concept and has the following configuration.

[0019] The decorative steel material of the first configuration comprises a steel material, a zinc-based plating layer, a primer layer, and an organic resin layer. The zinc-based plating layer is formed on the surface of the steel material, and a texture is formed on the surface. The primer layer is formed on the surface of the zinc-based plating layer. The organic resin layer is formed on the surface of the primer layer. The primer layer contains a binder and a first inorganic component. The organic resin layer is formed of a base resin containing a fluorine-based resin and an organic resin layer having a density of 0 to 0.0150 g / m in elemental terms. ２ and a second inorganic component, wherein the first inorganic component in the primer layer has an elemental equivalent film thickness of 0.0070 μm or more, and an inorganic component ratio, which is the ratio of the elemental equivalent content of the second inorganic component in the organic resin layer to the elemental equivalent content of the first inorganic component in the primer layer, is 0.7 or less.

[0020] The decorative steel material of the second configuration is the decorative steel material of the first configuration, and the first inorganic component of the primer layer contains a specific compound containing one or more selected from the group consisting of Ti and Zr, a phosphate compound, and a V compound.

[0021] The decorative steel material of the third configuration is the decorative steel material of the first or second configuration, and the second inorganic component contains a Group 4A metal compound.

[0022] The decorative steel material of the fourth configuration is the decorative steel material of any one of the first to third configurations, and the base resin further contains melamine resin.

[0023] The decorative steel material of the fifth configuration is the decorative steel material of any one of the first to fourth configurations, in which the zinc-based plating layer is made of Zn—Ni alloy plating.

[0024] The decorative steel material of this embodiment will be described in detail below.

[0025] [1. Regarding the decorative steel material 1] Figure 1 is a cross-sectional view perpendicular to the rolling direction of the decorative steel material 1 of this embodiment. In Figure 1, the rolling direction of the decorative steel material 1 is defined as the L direction. The thickness direction of the decorative steel material 1 is defined as the T direction. The direction perpendicular to the L direction and T direction of the decorative steel material 1 (i.e., the width direction of the decorative steel material 1) is defined as the W direction.

[0026] Referring to Figure 1, the decorative steel material 1 of this embodiment includes a steel material 10, a zinc-based plating layer 20, a primer layer 30, and an organic resin layer 40. The zinc-based plating layer 20 is formed on a surface 10S of the steel material 10. The primer layer 30 is formed on a surface 20S of the zinc-based plating layer 20. The organic resin layer 40 is formed on a surface 30S of the primer layer 30. The steel material 10, the zinc-based plating layer 20, the primer layer 30, and the organic resin layer 40 will be described below.

[0027] [2. Regarding the Steel Material 10] The steel material 10 may be any steel material suited to the mechanical properties (e.g., tensile strength, workability, etc.) required of the decorative steel material 1. In other words, the type of steel used for the steel material 10 is not particularly limited. Furthermore, the shape of the steel material 10 is not particularly limited. The chemical composition of the steel material 10 includes, for example, in mass %, C: 0.01 to 0.25%, Si: 0.001 to 1.200%, Mn: 0.01 to 2.50%, P: 0.001 to 0.200%, S: 0.001 to 0.050%, sol. Al (acid-soluble Al): 0.015 to 0.060%, and Fe: 95.0% or more. The steel material 10 may be, for example, a steel plate, a steel section, a steel pipe, or the like. For example, a steel plate for construction applications is used as the steel material 10.

[0028] [3. Regarding the zinc-based plating layer 20] The zinc-based plating layer 20 is formed on the surface 10S of the steel material 10. Fig. 2 is a plan view of the zinc-based plating layer 20. As shown in Fig. 2, a texture TX is formed on the surface 20S of the zinc-based plating layer 20. The types of zinc-based plating constituting the zinc-based plating layer 20 and the texture TX will be described below.

[0029] (3.1. Types of zinc-based plating constituting the zinc-based plating layer 20) The zinc-based plating layer 20 may be a plating layer made of zinc plating or a plating layer made of zinc alloy plating.

[0030] The zinc-based plating layer 20 is formed by a well-known plating process. The zinc-based plating layer 20 may be formed by, for example, either an electroplating method or a hot-dip plating method. In this specification, the zinc-based plating layer 20 may be a zinc plating layer or a zinc alloy plating layer. The zinc-based plating layer 20 is a concept that includes one or more of an electrogalvanized layer, an electrogalvanized zinc alloy plating layer, a hot-dip galvanized layer, and an alloyed hot-dip galvanized layer.

[0031] The zinc-based plating layer 20 may have any known chemical composition. The Zn content in the chemical composition of the zinc-based plating layer 20 is 65% by mass or more. If the Zn content is 65% by mass or more, the sacrificial corrosion protection function is significantly exhibited, and the corrosion resistance of the decorative steel material 1 is significantly improved. The lower limit of the Zn content in the chemical composition of the zinc-based plating layer 20 is preferably 70%, and more preferably 80%.

[0032] The chemical composition of the zinc-based plating layer 20 preferably contains Zn and one or more elements selected from the group consisting of Al, Co, Cr, Cu, Fe, Ni, P, Si, Sn, Mg, Mn, Mo, V, W, and Zr. When the zinc-based plating layer 20 is an electrogalvanized layer, the chemical composition of the zinc-based plating layer 20 more preferably contains a total of 5 to 20 mass% of one or more elements selected from the group consisting of Fe, Ni, and Co. When the zinc-based plating layer 20 is a hot-dip galvanized layer, the chemical composition of the zinc-based plating layer 20 more preferably contains a total of 5 to 20 mass% of one or more elements selected from the group consisting of Mg, Al, and Si. In these cases, the zinc-based plating layer 20 exhibits even better corrosion resistance.

[0033] Preferably, the zinc-based plating layer 20 is made of a Zn—Ni alloy plating. The Zn—Ni alloy plating has excellent corrosion resistance and high hardness. Therefore, the Zn—Ni alloy plating is suitable for the zinc-based plating layer 20.

[0034] When the entire chemical composition of the Zn—Ni alloy plating is taken as 100% by mass, the preferred Ni content is 10 to 20% by mass. In this case, the Zn—Ni alloy plating is a single γ phase. Therefore, the hardness of the Zn—Ni alloy plating is further increased. A more preferred lower limit of the Ni content is 11% by mass, even more preferably 12% by mass, and even more preferably 14% by mass. A more preferred upper limit of the Ni content is 18% by mass, even more preferably 17% by mass, and even more preferably 16% by mass. The Zn content is, for example, 80 to 90% by mass. Preferably, the Zn—Ni alloy plating consists of Zn and Ni.

[0035] The zinc-based plating layer 20 may contain impurities. Here, impurities refer to elements that are unintentionally mixed in raw materials or unintentionally mixed in during the manufacturing process. Examples of impurities include Ti, B, S, N, C, Nb, Pb, Cd, Ca, Pb, Y, La, Ce, Sr, Sb, O, F, Cl, Ag, and H. In the chemical composition of the zinc-based plating layer 20, the total content of impurities is preferably 1% or less.

[0036] (3.2. Method for Measuring the Chemical Composition of the Zinc-Based Plating Layer 20) The chemical composition of the zinc-based plating layer 20 can be measured, for example, by the following method. The organic resin layer 40 and primer layer 30 of the decorative steel material 1 are removed using a stripping agent such as a solvent or remover (e.g., Neo River S-701, product name, manufactured by Sansai Kako Co., Ltd.) that does not dissolve the zinc-based plating layer 20. The zinc-based plating layer 20 is then dissolved using a pickling inhibitor for hydrochloric acid. The solution of the zinc-based plating layer 20 is subjected to ICP (Inductively Coupled Plasma) analysis using an ICP emission spectrometer to determine the Zn content. If the determined Zn content is 65% or more by mass, the plating layer being measured is determined to be the zinc-based plating layer 20.

[0037] (3.3. Texture TX formed on surface 20S of zinc-based plating layer 20) Referring to Fig. 2, texture TX is formed on surface 20S of zinc-based plating layer 20. Texture TX refers to an uneven pattern formed on surface 20S of zinc-based plating layer 20 by a physical or chemical method. Texture TX is a three-dimensional uneven pattern on surface 20S of zinc-based plating layer 20. Examples of texture TX include well-known hairlines, embossments, dots, vibrations, matte (blasted), hammered, and satin. Preferably, texture TX is a hairline.

[0038] [4. Primer Layer 30] The primer layer 30 is formed on the surface 20S of the zinc-based plating layer 20. More specifically, the primer layer 30 is formed on the texture TX formed on the surface 20S. The primer layer 30 contains a binder and a first inorganic component. The binder and the first inorganic component will be described below.

[0039] (4.1. Regarding the binder in the primer layer 30) The binder is a binding agent that holds the first inorganic component within the primer layer 30 and suppresses elution of the first inorganic component. There are no particular limitations on the binder as long as it exhibits the above-mentioned effects. The binder is, for example, one or more types selected from the group consisting of well-known natural resins, well-known synthetic resins, and organosilicon compounds. The synthetic resin is, for example, one or more types selected from the group consisting of epoxy-based resins, urethane-based resins, and acrylic-based resins. The synthetic resin may be a resin other than epoxy-based resins, urethane-based resins, and acrylic-based resins.

[0040] Preferably, the binder is an organosilicon compound. An organosilicon compound is a compound in which silicon (Si) and an organic group (hydrocarbon group) are bonded together. The type of organosilicon compound is not particularly limited. An organosilicon compound has a skeleton containing Si. Therefore, the bond energy of organosilicon compounds is higher than that of organic resins consisting of a carbon skeleton. Therefore, organosilicon compounds have better weather resistance than natural resins and synthetic resins.

[0041] Preferably, the organosilicon compound is a silane coupling agent. The silane coupling agent has a reactive functional group and a hydrolyzable group. The reactive functional group of the silane coupling agent bonds with the organic material (organic resin), and the hydrolyzable group bonds with the inorganic material. Therefore, the silane coupling agent can improve adhesion to the zinc-based plating layer 20 while also improving adhesion to the organic resin layer 40.

[0042] (4.2. First inorganic component in primer layer 30) The first inorganic component in the primer layer 30 enhances corrosion resistance. The first inorganic component contains at least a compound containing one or more elements selected from the group consisting of Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, and Ce. The compound here is, for example, an oxide and / or hydroxide. Note that the first inorganic component may also contain inorganic components other than those described above. In the following description, Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, and Ce will also be referred to as target elements of the first inorganic component.

[0043] Preferably, the first inorganic component contains a specific compound containing at least one element selected from the group consisting of Ti and Zr, a phosphate compound, and a vanadium compound. When these inorganic components are contained, corrosion resistance is significantly improved. The specific compound, the phosphate compound, and the vanadium compound are described below.

[0044] (4.2.1. Regarding the specific compound) The specific compound is a compound containing Ti and / or Zr. The specific compound is easily reactive with reactive functional groups. Therefore, the specific compound promotes the curing and crosslinking reaction of the binder, thereby increasing the density of the primer layer 30. As a result, the specific compound significantly improves corrosion resistance.

[0045] The Ti compound is a compound containing Ti, and is at least one selected from the group consisting of Ti oxide, Ti hydroxide, Ti complex compound, salt of Ti with inorganic acid, and salt of Ti with organic acid. For example, the Ti compound is titanyl sulfate (TIOSO ４ ), titanium lactate, diisopropoxytitanium bisacetylacetone {(C ５ H ７ O ２ ) ２ Ti[OCH(CH ３ ) ２ ] ２ and a reaction product of lactic acid with titanium alkoxide.

[0046] The Zr compound is a compound containing Zr, and is at least one selected from the group consisting of Zr oxide, Zr hydroxide, Zr complex compound, salt of Zr with an inorganic acid, and salt of Zr with an organic acid. For example, the Zr compound is zirconyl nitrate (ZrO(NO ３ ) ２ ), zirconyl acetate, zirconyl sulfate, ammonium zirconium carbonate {(NH ４ ) ２ [Zr(CO ３ ) ２ (OH) ２ ]}, and zirconium acetate.

[0047] (4.2.2. Regarding Phosphate Compounds) Phosphate compounds significantly improve corrosion resistance. There are no particular limitations on the phosphate compound. For example, the phosphate compound is one or more selected from the group consisting of phosphoric acid, ammonium phosphate salts, potassium phosphate salts, sodium phosphate salts, etc. Preferably, the phosphate compound is phosphoric acid. When the primer layer 30 contains phosphoric acid, corrosion resistance is further improved.

[0048] (4.2.3. Regarding V Compounds) V compounds significantly improve corrosion resistance. There are no particular limitations on the V compound as long as it contains V. For example, vanadium pentoxide V ２ O ５ , metavanadate HVO ３ , ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride VOCl ３ , vanadium trioxide V ２ O ３ , vanadium dioxide VO ２ , vanadium oxysulfate VOSO ４ , vanadium oxyacetylacetonate VO(OC(=CH ２ ) CH ２ COCH ３ ) ２ , vanadium acetylacetonate V(OC(=CH ２ ) CH ２ COCH ３ ) ３ , and vanadium trichloride VCl ３ The V compound may also be one or more selected from the group consisting of: a pentavalent V compound reduced to a tetravalent to divalent V compound by an organic compound having at least one functional group selected from the group consisting of a hydroxyl group, a carbonyl group, a carboxyl group, a primary to tertiary amino group, an amide group, a phosphoric acid group, and a phosphonic acid group.

[0049] (4.3. Regarding the equivalent elemental thickness ET of the first inorganic component in the primer layer 30) In this specification, the thickness of the first inorganic component in the primer layer 30 in terms of elemental equivalent is referred to as the equivalent elemental thickness ET (Equivalent Thickness). The equivalent elemental thickness ET of the first inorganic component in the primer layer 30 is 0.0070 μm or more. If the equivalent elemental thickness ET is 0.0070 μm or more, the primer layer 30 contains a sufficient amount of the first inorganic component. Therefore, sufficient corrosion resistance can be obtained in the decorative steel material 1.

[0050] The lower limit of the equivalent elemental thickness ET is preferably 0.0090 μm, more preferably 0.0100 μm, even more preferably 0.0110 μm, even more preferably 0.0120 μm, even more preferably 0.0125 μm, even more preferably 0.0150 μm, even more preferably 0.0200 μm, even more preferably 0.0250 μm, even more preferably 0.0280 μm, and even more preferably 0.0300 μm.

[0051] The upper limit of the equivalent elemental thickness ET is not particularly limited. Preferably, the upper limit of the equivalent elemental thickness ET is 0.2000 μm. When the equivalent elemental thickness ET is 0.2000 μm or less, the occurrence of interference colors in the primer layer 30 is significantly suppressed. Therefore, the texture formed on the surface of the zinc-based plating layer 20 can be clearly seen, and the design properties of the texture can be significantly improved.

[0052] A more preferable upper limit of the equivalent elemental thickness ET is 0.1800 μm, even more preferably 0.1500 μm, even more preferably 0.1000 μm, even more preferably 0.0800 μm, even more preferably 0.0700 μm, even more preferably 0.0650 μm, and even more preferably 0.0500 μm.

[0053] (4.3.1. Method for Measuring Equivalent Elemental Film Thickness ET) The equivalent elemental film thickness ET of the first inorganic component in the primer layer 30 can be measured by the following method. Glow discharge optical emission spectroscopy (GDS) is performed in the thickness direction of the primer layer 30 of the decorative steel material 1 (normal direction to the surface of the decorative steel material 1). Specifically, in a neon atmosphere of 1800 Pa, an output power of 5 W is applied using the decorative steel material 1 as the cathode to cause glow discharge to emit light. Then, the emission spectrum of each element is measured from the surface of the organic resin layer 40 over the entire thickness direction of the organic resin layer 40 and the primer layer 30, and the emission intensity is recorded. The measurement area is 4 mm in diameter, and the measurement interval is 0.02 seconds. A spectrometer is used to measure the emission spectrum.

[0054] In GDS, the detection targets are target elements (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, and Ce) that may be contained in the first inorganic component, fluorine (F) contained in the organic resin layer 40 described below, C, O, and Si contained in the organic resin layer 40 and the primer layer 30, and Zn contained in the zinc-based plating layer 20.

[0055] In the emission spectrum graph, the interface between the organic resin layer 40 and the primer layer 30 and the interface between the primer layer 30 and the zinc-based plating layer 20 are identified by the following method. Fig. 3 is a schematic diagram showing an example of fluorine (F) and carbon (C) emission spectra obtained by GDS. Referring to Fig. 3, when proceeding in the thickness direction from the surface of the organic resin layer 40 (position "0" on the horizontal axis of the graph in Fig. 3), the emission intensity of fluorine reaches a peak I at position P0. Ｆ The fluorine emission intensity rapidly decreases from the peak position P0, and then decreases to half of the emission intensity at the peak position P0 (I Ｆ / 2) is determined to be the interface between the organic resin layer 40 and the primer layer 30. Furthermore, the maximum value I of the emission intensity of C at a depth equal to or less than the position P1 is determined to be Ｃ In FIG. 3, at a depth equal to or less than the position P1, the emission intensity of C at the position P1 is the maximum value I Ｃ At a depth equal to or less than the position P1, the emission intensity of C reaches a maximum value I Ｃ Half of (I Ｃ / 2) is determined to be the interface between the primer layer 30 and the zinc-based plating layer 20.

[0056] In the region of the emission spectrum graph that is identified as the primer layer 30, the emission intensity of each of the target elements (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, and Ce) is applied to a calibration curve to determine the concentration (mass %) of each of the above-mentioned elements that may be contained in the primer layer 30.

[0057] Next, the thickness of the primer layer 30 is determined using the following method. A test specimen including a cross section (hereinafter referred to as the observation surface) parallel to the normal direction (i.e., the thickness direction) of the surface of the decorative steel material 1 and including the organic resin layer 40 and the primer layer 30 is taken. Au (heavy metal) is vapor-deposited on the surface of the organic resin layer 40 of the test specimen to form a vapor-deposited layer on the surface of the organic resin layer 40. The test specimen with the vapor-deposited layer formed is embedded in resin, and the observation surface is polished. The observation surface of the test specimen is observed using a scanning electron microscope (SEM) to obtain a backscattered electron image. In the backscattered electron image, the organic resin layer 40, the primer layer 30, and the zinc-based plating layer 20 can be easily distinguished by contrast. The magnification of the SEM is adjusted to the largest field of view possible in which the interface between the organic resin layer 40 and the primer layer 30 and the interface between the primer layer 30 and the zinc-based plating layer 20 can be observed. The thickness (μm) is measured at any 10 locations on the primer layer 30. The arithmetic mean value of the measurements at 10 locations is defined as the thickness (μm) of the primer layer 30 .

[0058] The total concentration (mass %) of each of the target elements (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, and Ce) of the first inorganic component in the obtained primer layer 30 is calculated, and the obtained total concentration is regarded as the total concentration (mass %) of the elements in the first inorganic component.

[0059] Here, the equivalent elemental thickness ET is expressed by the following formula: Equivalent elemental thickness ET = Thickness of primer layer 30 × Density of primer layer 30 × Total concentration of target elements of first inorganic component / 100 × Average density of target elements of first inorganic component Here, in this specification, the density of the primer layer 30 is defined as 1.8 g / cm ３ In addition, the average density of the target element in the first inorganic component is set to 1.2 g / cm３ Therefore, the above formula can be expressed as follows: Equivalent elemental thickness ET = Thickness of primer layer 30 × Total concentration of elements in first inorganic component / 100 × 1.8 / 1.2 = Thickness of primer layer 30 × Total concentration of elements in first inorganic component / 100 × 1.5 The equivalent elemental thickness ET is the value obtained by rounding the obtained value to the fifth decimal place (i.e., the value to the fourth decimal place).

[0060] It is difficult to measure the density of the primer layer 30. The density of the primer layer 30 is set to 1.8 g / cm ３ If this is the case, even if the composition of the primer layer 30 varies, the obtained equivalent elemental thickness ET will be correlated with the effect. Similarly, it is difficult to measure the average density of the first inorganic component. If the average density of the first inorganic component is 1.2 g / cm ３ In this case, even if the composition of the first inorganic component varies, the obtained equivalent elemental film thickness ET can be correlated with the effect.

[0061] [5. Regarding the organic resin layer 40] The organic resin layer 40 is formed on the surface 30S of the primer layer 30. The organic resin layer 40 is translucent. Here, "translucent" means that when the decorative steel material 1 provided with the organic resin layer 40 is placed in an environment equivalent to sunlight on a clear morning (illuminance of approximately 65,000 lux), the texture TX formed on the surface 20S of the zinc-based plating layer 20 is visible.

[0062] The organic resin layer 40 is made of a base resin containing a fluorine-based resin and an organic compound having an elemental equivalent of 0 to 0.0150 g / m ２ The base resin and the second inorganic component will be described below.

[0063] (5.1. Base resin) The base resin contains a fluororesin as a main component. The base resin may be composed solely of a fluororesin. Alternatively, the base resin may contain a fluororesin and another resin.

[0064] (5.1.1. Regarding Fluorine-Based Resins) Fluorine-based resins are resins that contain fluorine. Fluorine-based resins have fluorine-carbon bonds. Fluorine-carbon bonds are strong and stable. Therefore, fluororesins have excellent weather resistance and corrosion resistance.

[0065] The fluororesin is, for example, a copolymer of a fluoroolefin and a reactive functional group-containing monomer. The fluoroolefin is, for example, one or more selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, vinyl fluoride, perfluoroolefin, vinylidene fluoride, pentafluoropropylene, 2,2,3,3-tetrafluoropropylene, 3,3,3-trifluoropropylene, bromotrifluoroethylene, 1-chloro-1,2-difluoroethylene, and 1,1-dichloro-2,2-difluoroethylene.

[0066] From the viewpoint of weather resistance, the preferred fluoroolefin is at least one of perfluoroolefin and vinylidene fluoride. Examples of perfluoroolefin include tetrafluoroethylene and hexafluoropropylene.

[0067] From the viewpoint of corrosion resistance, preferred fluoroolefins are one or more selected from the group consisting of tetrafluoroethylene, trifluoroethylene, hexafluoropropylene, vinyl fluoride, vinylidene fluoride, pentafluoropropylene, 2,2,3,3-tetrafluoropropylene, 3,3,3-trifluoropropylene, and bromotrifluoroethylene. These fluoroolefins do not contain chlorine, and therefore, even better corrosion resistance can be obtained.

[0068] The reactive functional group-containing monomer is, for example, one or more selected from the group consisting of carboxyl group-containing monomers and sulfonic acid group-containing monomers.

[0069] The fluorine content in the fluororesin is not particularly limited. A preferred range of the fluorine content in the fluororesin is 7 to 20% by mass. A fluorine content of 7% or more provides significantly superior weather resistance in the organic resin layer 40. On the other hand, a fluorine content of 20% or less significantly facilitates the organic resin layer 40 being used as a raw material for paint. Furthermore, the adhesion of the organic resin layer 40 is significantly improved, and excellent drying properties are achieved. The fluorine content in the fluororesin can be measured by subjecting the fluororesin to XRF analysis using an X-ray fluorescence analyzer. Whether or not the base resin contains a fluororesin can be determined by detecting the presence or absence of fluorine using a gas chromatograph mass spectrometer (GC-MS).

[0070] (5.1.2. Regarding Resins Other Than Fluorine-Based Resins in the Base Resin) The base resin may be composed solely of a fluorine-based resin, or may contain a fluorine-based resin and a resin other than a fluorine-based resin. The resin other than a fluorine-based resin may be a well-known natural resin and / or a well-known synthetic resin. The resin other than a fluorine-based resin may be, for example, one or more resins selected from the group consisting of melamine resin, epoxy resin, urethane resin, polyester resin, phenol resin, polyethersulfone resin, acrylic resin, polyamide resin, polyimide resin, polyvinyl acetate resin, polyolefin resin, polystyrene resin, vinyl chloride resin, and vinyl acetate resin.

[0071] Preferably, the base resin contains a fluorine-based resin and a melamine resin. The melamine resin crosslinks with the fluorine-based resin to further enhance the weather resistance of the organic resin layer 40. The melamine resin is a compound obtained by etherifying a methylolmelamine derivative obtained by condensing melamine and formaldehyde with a lower alcohol (such as methyl alcohol, ethyl alcohol, or isopropyl alcohol), or a mixture thereof. The methylolmelamine derivative may be, for example, one or more selected from the group consisting of monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, and hexamethylolmelamine.

[0072] When the base resin contains a resin other than a fluorine-based resin, the content of the fluorine-based resin in the base resin is preferably 30 to 90% by mass.

[0073] (5.2. Second Inorganic Component) The organic resin layer 40 may contain a second inorganic component. That is, the organic resin layer 40 does not necessarily contain a second inorganic component. When the second inorganic component is contained, the second inorganic component is contained for various purposes. For example, the second inorganic component is contained to enhance corrosion resistance. The second inorganic component may also be contained as a gloss adjuster.

[0074] The second inorganic component contained in the organic resin layer 40 contains at least a compound containing one or more elements selected from the group consisting of Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, Ce, and Si. The compound referred to here is, for example, an oxide and / or hydroxide. The second inorganic component may also contain inorganic components other than those listed above. In the following description, Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, Ce, and Si are also referred to as target elements of the second inorganic component.

[0075] Preferably, the second inorganic component contains a Group 4A metal compound. The Group 4A metal compound is a compound containing one or more Group 4A elements selected from the group consisting of Ti, Zr, Hf, and Rf. The Group 4A metal compound easily reacts with reactive functional groups, such as carboxyl groups and sulfonic acid groups, in the fluororesin. Therefore, the Group 4A metal compound promotes the curing and crosslinking reaction of the fluororesin. As a result, the corrosion resistance of the organic resin layer 40 is further improved.

[0076] (5.3. Content of the Second Inorganic Component in Elemental Equivalent) In this embodiment, the content of the second inorganic component per unit area (g / m) in the organic resin layer 40 is further calculated. ２ ) is 0 to 0.0150 g / m in terms of element. ２ Here, the content "in terms of elements" refers to the total content (g / m) of the target elements (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, Ce, and Si) of the second inorganic component. ２ The content of the second inorganic component in terms of element is 0.0150 g / m２ If the content of the second inorganic component exceeds 100%, an excess of the second inorganic component will be present in the organic resin layer 40. In this case, light incident on the organic resin layer 40 will be scattered by the second inorganic component. As a result, it will be difficult to clearly recognize the texture TX formed on the zinc-based plating layer 20. As a result, the designability of the decorative steel material 1 will be reduced.

[0077] The content of the second inorganic component in terms of element is 0.0150 g / m ２ If the content of the second inorganic component in the organic resin layer 40 is below this range, the content of the second inorganic component in the organic resin layer 40 is sufficiently reduced, and therefore, scattering of light incident on the organic resin layer 40 can be sufficiently suppressed. As a result, the texture TX formed on the zinc-based plating layer 20 can be clearly recognized, and excellent design properties can be obtained.

[0078] The preferred upper limit of the content of the second inorganic component in terms of element is 0.0130 g / m ２ and more preferably 0.0120 g / m ２ and more preferably 0.0100 g / m ２ and more preferably 0.0085 g / m ２ and more preferably 0.0075 g / m ２ and more preferably 0.0060 g / m ２ The content of the second inorganic component is 0 g / m ２ may be.

[0079] (5.3.1. Elemental content of second inorganic component (g / m ２ ) Measurement method) Content (g / m) of the second inorganic component in the organic resin layer 40 in terms of element ２ ) can be measured by the following method. The GDS described above in (4.3.1. Method for measuring equivalent elemental film thickness ET) is performed. Using the method described in (4.3.1. Method for measuring equivalent elemental film thickness ET), the interface between the organic resin layer 40 and the primer layer 30 and the interface between the primer layer 30 and the zinc-based plating layer 20 are identified in the emission spectrum graph.

[0080] In the region of the emission spectrum graph identified as the organic resin layer 40, the emission intensity of each of the target elements of the second inorganic component (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, Ce, and Si) is fitted to a calibration curve to determine the concentration (mass %) of each element.

[0081] Next, the thickness of the organic resin layer 40 is determined by the following method. A sample including the organic resin layer 40 and a cross section (hereinafter referred to as the observation surface) parallel to the normal direction (thickness direction) of the surface of the decorative steel material 1 is taken. Au (heavy metal) is vapor-deposited on the surface of the organic resin layer 40 to form a vapor-deposited layer on the surface of the organic resin layer 40. The sample with the vapor-deposited layer formed is embedded in resin, and the observation surface is polished to prepare a sample. The observation surface of the sample is observed using an SEM to obtain a backscattered electron image. As described above, in the backscattered electron image, the organic resin layer 40 and the primer layer 30 can be easily distinguished by contrast. The magnification of the SEM is adjusted to the largest field of view possible in which the interface between the organic resin layer 40 and the Au vapor-deposited layer and the interface between the organic resin layer 40 and the primer layer 30 can be observed. The thickness (μm) is measured at any 10 locations on the organic resin layer 40. The arithmetic mean value of the 10 measured locations is defined as the thickness (μm) of the organic resin layer 40.

[0082] The total concentration (mass %) of the obtained target elements (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, Ce, and Si) of the second inorganic component is calculated. The obtained total concentration is regarded as the total concentration of the target elements of the second inorganic component. The total concentration (mass %) of the target elements of the second inorganic component and the density (g / m) of the organic resin layer 40 are used as the reference concentration. ３ ) and the thickness (μm) of the organic resin layer 40, the content of the second inorganic component converted into elements is calculated by the following formula: ２ ) = (total concentration of target elements of the second inorganic component (mass %) / 100) × density of the organic resin layer 40 (g / m ３ ) × thickness (m) of the organic resin layer 40. Here, the density of the organic resin layer 40 in this embodiment is 1.1 to 1.4 g / cm ３ Therefore, assuming a calculation under more severe conditions, the density of the organic resin layer 40 is set to 1.4 g / cm ３The content in elemental terms of the second inorganic component is the value obtained by rounding off the obtained value to the fifth decimal place (i.e., the value to the fourth decimal place). As described above, the content in elemental terms of the second inorganic component (content in elemental terms) is the total content (g / m) of the target elements (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, Ce, and Si) of the second inorganic component in the organic resin layer 40. ２ ) is equivalent to

[0083] (5.4. Other Components That Can Be Included in the Organic Resin Layer 40) In addition to the base resin containing the fluorine-based resin and the second inorganic component, the organic resin layer 40 may further include one or more components selected from the group consisting of a pigment, organic resin particles, a leveling agent, and an antifoaming agent. The pigment, organic resin particles, leveling agent, and antifoaming agent will be described below.

[0084] (5.4.1. Pigments) Pigments are fine particles (powder) that are insoluble in water and oil. The pigments color the organic resin layer 40 when contained in the organic resin layer 40. Pigments are well known and may be inorganic or organic pigments. The pigments are chromatic color pigments. A chromatic color means a color that has the attributes of hue, lightness, and saturation.

[0085] When the pigment is an inorganic pigment, the pigment is, for example, one or more selected from the group consisting of neutralized precipitate pigments (sulfates, carbonates, etc.) and calcined pigments (metal sulfides, metal oxides, polyvalent metal composite oxides, etc.). When the pigment is an organic pigment, the pigment is, for example, one or more selected from the group consisting of chlorine pigments, azo pigments (soluble azo lake pigments, insoluble azo pigments, etc.), acid condensation pigments, polycyclic pigments (phthalocyanine pigments, indigo pigments, quinacridone pigments, anthraquinone pigments, etc.), and metal complex pigments (azo chelate pigments, transition metal complex pigments, etc.).

[0086] The color of the pigment is not particularly limited. Examples of the pigment include carbon black (C), iron black (Fe ３ O ４ However, the pigment is not limited to a black pigment, and may be a pigment of other colors (white, purple-red, yellow, green-blue, red, orange, green, blue, indigo blue, purple, etc.).

[0087] When the organic resin layer 40 contains an inorganic pigment, the inorganic component contained in the inorganic pigment is considered to be the second inorganic component. Therefore, even when the organic resin layer 40 contains an inorganic pigment, the content of the second inorganic component contained in the organic resin layer 40 in terms of elements is 0 to 0.0150 g / m ２ The preferred content of the pigment in the organic resin layer 40 is 0 to 4.0% by mass.

[0088] The particle size of the pigment is not particularly limited. However, pigments absorb visible light to develop color. Therefore, taking into account the wavelength of visible light, the preferred lower limit of the particle size of the pigment is more than 180 nm. The upper limit of the particle size of the pigment is not particularly limited. The preferred upper limit of the particle size of the pigment is 1000 nm, more preferably 800 nm, and even more preferably 700 nm.

[0089] (5.4.2. Organic Resin Particles) The organic resin particles are composed of a different type of resin from the base resin. The organic resin particles are, for example, one or more types selected from the group consisting of urethane-based resin particles, acrylic-based resin particles, hard polyethylene-based resin particles, polyethylene-based resin particles, polypropylene-based resin particles, and PTFE (polytetrafluoroethylene) particles. The organic resin particles are also called wax.

[0090] Preferably, the organic resin particles satisfy at least one of the following (Configuration 1) and (Configuration 2). (Configuration 1) The hardness of the organic resin particles is higher than that of the base resin. (Configuration 2) The surface free energy of the organic resin particles is lower than that of the base resin, so the friction coefficient of the resin particles is lower than that of the base resin. A portion of the organic resin particles may protrude outward from the base resin. The organic resin particles are harder or have a lower friction coefficient than the base resin. Therefore, the occurrence of scratches due to collision or contact with flying objects, etc. can be suppressed.

[0091] (5.4.3. Regarding Leveling Agents) The leveling agent adjusts the surface tension of the organic resin layer composition paint that is the raw material of the organic resin layer 40, and smooths the surface of the organic resin layer composition paint after the organic resin layer composition paint is applied. This makes it possible to prevent the occurrence of irregularities and unevenness on the surface of the organic resin layer 40. Examples of leveling agents include fluorine-based surfactants, silicone-based surfactants, and acrylic resins.

[0092] (5.4.4. Antifoaming Agent) The antifoaming agent suppresses bubbles that are generated in the organic resin layer composition coating material, which is a slurry. Examples of the antifoaming agent include silicone-based antifoaming agents, non-silicone-based antifoaming agents, mineral oil-based antifoaming agents, and glycerin esters.

[0093] (5.5. Preferred Thickness of Organic Resin Layer 40) The preferred thickness of the organic resin layer 40 is 1.00 to 10.00 μm. A more preferred lower limit of the thickness of the organic resin layer 40 is 1.50 μm, more preferably 1.80 μm, even more preferably 2.00 μm, even more preferably 2.30 μm, even more preferably 2.50 μm, and even more preferably 3.00 μm. A more preferred upper limit of the thickness of the organic resin layer 40 is 9.80 μm, even more preferably 9.50 μm, even more preferably 9.00 μm, even more preferably 8.50 μm, even more preferably 8.00 μm, even more preferably 7.00 μm, and even more preferably 6.00 μm.

[0094] The thickness of the organic resin layer 40 is determined based on the above-mentioned (5.3.1. Content of the second inorganic component in terms of element (g / m ２ ) is measured by the method described in ).

[0095] [6. Inorganic Component Ratio ICR] In the decorative steel material 1 of this embodiment, the inorganic component ratio ICR, which is the ratio of the content of the second inorganic component in the organic resin layer 40 in elemental terms to the content of the first inorganic component in the primer layer 30 in elemental terms, is 0.7 or less. The inorganic component ratio ICR will be described below.

[0096] The inorganic component ratio (ICR) is an index related to the design quality of the texture. When the inorganic component ratio (ICR) exceeds 0.7, the amount of the second inorganic component in the organic resin layer 40 is too high relative to the amount of the first inorganic component in the primer layer 30. Alternatively, the amount of the first inorganic component in the primer layer 30 is too low relative to the amount of the second inorganic component in the organic resin layer 40. In this case, the texture formed on the surface of the zinc-based plating layer 20 may not be clearly visible, may appear blurred, or may not have sufficient corrosion resistance. In other words, the design quality of the texture may be reduced, or the corrosion resistance may be reduced. When the inorganic component ratio (ICR) is 0.7 or less, the amount of the second inorganic component in the organic resin layer 40 is sufficiently low relative to the amount of the first inorganic component in the primer layer 30. Therefore, scattering of visible light in the organic resin layer 40 is sufficiently suppressed, and the texture formed on the surface of the zinc-based plating layer 20 is clearly visible. In other words, the design quality of the texture can be improved while maintaining corrosion resistance.

[0097] The upper limit of the inorganic component ratio ICR is preferably 0.6, more preferably 0.5, even more preferably 0.4, even more preferably 0.3, and even more preferably 0.2.

[0098] (6.1. Method for Measuring Inorganic Component Ratio ICR) The inorganic component ratio ICR can be measured by the following method. The method described in (4.3.1. Method for Measuring Equivalent Elemental Film Thickness ET) above is carried out. Based on the total concentration of elements in the first inorganic component of the obtained primer layer 30, the density of the primer layer 30, and the thickness of the primer layer 30, the equivalent elemental content (g / m) of the first inorganic component is calculated. ２ The elemental content (g / m) of the first inorganic component is calculated using the following formula: ２ ) = (total concentration of target elements in the first inorganic component (mass%) / 100) × density of primer layer 30 (g / m ３ ) × thickness (m) of the primer layer 30 In other words, the content of the first inorganic component in elemental terms (elemental content) is the total content (g / m) of the target elements (Ti, Zr, Hf, Rf, P, V, Mg, Ca, Li, Ba, Nb, and Ce) of the first inorganic component in the primer layer 30. ２ ) is equivalent to

[0099] The obtained content of the first inorganic component in terms of element (g / m ２ ) and the above-mentioned (5.3.1. Content of the second inorganic component in terms of element (g / m ２ ) measurement method) of the second inorganic component in terms of element content (g / m ２ ) and the inorganic component ratio ICR is calculated by the following formula: Inorganic component ratio ICR = Content of second inorganic component in elemental equivalent / Content of first inorganic component in elemental equivalent Here, the inorganic component ratio ICR is the value obtained by rounding off the obtained value to one decimal place (i.e., the value to one decimal place).

[0100] 7. Effects of the Designable Steel Material 1 The designable steel material 1 having the above configuration has excellent corrosion resistance and weather resistance, even when used outdoors, and has excellent texture design. Therefore, the designable steel material 1 can be widely applied to, for example, building materials used outdoors.

[0101] [8. Manufacturing method of the decorative steel material 1] The decorative steel material 1 of this embodiment can be manufactured, for example, by the following method. An example of a manufacturing method of the decorative steel material 1 will be described below. The example of a manufacturing method of the decorative steel material 1 includes the following steps: (Step 1) Steel material preparation step (Step 2) Plating layer formation step (Step 3) Texture formation step (Step 4) Primer layer formation step (Step 5) Organic resin layer formation step Each step will be described below.

[0102] (Step 1) Steel Material Preparing Step In the steel material preparing step, the above-described steel material 10 is prepared. As described above, the steel material 10 is, for example, a steel plate, a steel section, a steel pipe, or the like.

[0103] (Step 2) Plating Layer Forming Step In the plating layer forming step, a zinc-based plating layer 20 is formed on the surface 10S of the steel material 10 by electrogalvanizing or hot-dip galvanizing. For example, the following electrogalvanizing or hot-dip galvanizing method is performed to form the zinc-based plating layer 20.

[0104] (Electrogalvanizing Method) When forming the zinc-based plating layer 20 by electrogalvanizing, the electrogalvanizing method may be performed by a known method. In this specification, the term "electrogalvanizing method" also includes electrogalvanizing methods such as zinc alloy plating. The plating solution used in the electrogalvanizing method may be a known electrogalvanizing solution. Examples of electrogalvanizing solutions include sulfate baths, chloride baths, zincate baths, cyanide baths, pyrophosphate baths, boric acid baths, citric acid baths, other complex baths, and combinations thereof. The electrogalvanizing solution may contain, in addition to Zn ions, one or more single ions or complex ions selected from the group consisting of one or more of Fe, Ni, and Co. Furthermore, organic additives may be added to the electrogalvanizing solution or electrogalvanizing solution to achieve desired effects such as leveling or increased hardness.

[0105] (Hot-dip galvanizing method) When forming the zinc-based plating layer 20 by hot-dip galvanizing, the hot-dip galvanizing method may be performed by a known method. A known plating bath may be used in the hot-dip galvanizing method. The plating bath may contain, for example, Al, with the balance being Zn and impurities. The impurities may be, for example, Fe. For example, the plating bath may further contain, in addition to Zn, Al, and Fe, one or more elements selected from the group consisting of Co, Cr, Cu, Ni, P, Si, Sn, Mg, Mn, Mo, V, W, and Zr.

[0106] Through the above manufacturing process, a zinc-based plating layer 20 is formed on the surface 10S of the steel material 10.

[0107] (Step 3) Texture Forming Step In the texture forming step, texture processing is performed on the surface 20S of the zinc-based plating layer 20 to form a texture TX on the surface 20S.

[0108] When the texture TX is a hairline, a known hairline processing is performed. Examples of hairline processing include a method of forming a hairline by polishing the surface with a known abrasive belt, a method of forming a hairline by polishing the surface with a known abrasive brush, and a method of forming a hairline by rolling and transferring the hairline with a roll to which a hairline shape has been imparted. The length, depth, and frequency of the hairline can be adjusted by adjusting the grain size of the known abrasive belt, the grain size of the known abrasive brush, or the surface shape of the roll. Note that, from the viewpoint of surface quality, the hairline processing method of forming a hairline by polishing the surface with an abrasive belt or an abrasive brush is preferred.

[0109] When the texture TX is an uneven shape such as embossment, dots, or vibration, a well-known transfer method using a roll may be performed. Specifically, a roll on which the texture TX having an uneven shape such as an embossment is formed is prepared. The prepared roll is pressed against the surface 20S of the zinc-based plating layer 20 to transfer the uneven shape formed on the roll to the surface 20S. Through the above steps, the uneven shape such as an embossment can be formed on the surface 20S of the zinc-based plating layer 20.

[0110] (Step 4) Primer Layer Forming Step In the primer layer forming step, a primer layer 30 is formed on the surface 20S of the zinc-based plating layer 20 on which the texture TX has been formed. The production line used in the primer layer forming step includes a conveying line and, arranged in this order from upstream to downstream of the conveying line, a paint application device and a baking furnace.

[0111] The conveying line conveys a steel material 10 having a zinc-based plating layer 20 on which a texture TX is formed. A paint application device is arranged on the conveying line. The paint application device applies a primer layer composition paint (chemical), which is a raw material for the primer layer 30, to the surface 20S of the zinc-based plating layer 20. The paint application device is, for example, a well-known coater. Well-known coaters include, for example, a die coater, a roll coater, and a curtain coater. The primer layer composition paint is a chemical, which is a raw material for the primer layer 30. The primer layer composition paint contains a binder and a first inorganic component.

[0112] The baking oven is disposed on the conveying line downstream of the coating device. The baking oven dries and bakes the primer layer composition coating applied to the surface 20S by the coating device to form the primer layer 30. The maximum temperature (Peak-Metal-Temperature: PMT) (°C) in the baking oven is set to, for example, 50 to 250°C.

[0113] Preferably, in the primer layer forming step, the composition of the primer layer composition paint and the coating amount of the primer layer composition paint are adjusted so that the elemental equivalent film thickness ET of the first inorganic component in the formed primer layer 30 is 0.0125 to 0.2000 μm.

[0114] (Step 5) Organic Resin Layer Forming Step In the organic resin layer forming step, an organic resin layer 40 is formed on the surface 30S of the primer layer 30. The production line used in the organic resin layer forming step includes a conveying line, and, from upstream to downstream of the conveying line, a paint application device and a baking furnace.

[0115] The steel material 10 on which the primer layer 30 has been formed is transported along the transport line. A paint application device is arranged on the transport line. The paint application device applies an organic resin layer composition paint (chemical), which is a raw material for the organic resin layer 40, to the surface 30S of the primer layer 30 of the steel material 10. The paint application device is, for example, a well-known coater. The organic resin layer composition paint is a chemical that is a raw material for the organic resin layer 40. The organic resin layer composition paint contains a base resin and optionally contains a second inorganic component.

[0116] The baking furnace is disposed on the conveying line downstream of the coating device. The baking furnace dries and bakes the organic resin layer composition coating applied to the surface 30S of the primer layer 30 by the coating device to form the organic resin layer 40. The maximum temperature PMT (°C) of the baking furnace is set to, for example, 150 to 250°C.

[0117] In steps 4 and 5, the composition and deposition amount of the primer layer composition paint and the composition and deposition amount of the organic resin layer composition paint are adjusted so that the inorganic component ratio ICR is 0.7 or less. After the primer layer composition paint has sufficiently dried to form the primer layer 30, the organic resin layer formation step is carried out.

[0118] The decorative steel material 1 of this embodiment is manufactured by the above manufacturing process. The decorative steel material 1 may also be manufactured by other manufacturing methods. The above manufacturing method is one example of a method for manufacturing the decorative steel material 1.

[0119] The effects of the decorative steel material 1 of this embodiment will be explained more specifically below using examples.

[0120] [Production of Designable Steel Sheets] Designable steel sheets with test numbers shown in Table 1 were produced by the following production process.

[0121]

[0122] [Steel Material Preparation Step] Plated steel sheets were prepared with the test numbers shown in Table 1. The steel sheets of each plated steel sheet were SPCC as specified in JIS G 3141 (2017), and had a thickness of 0.6 mm.

[0123] [Plated layer formation step] A zinc-based plating layer of the type shown in the "Type" column of the "Zinc-based plating layer" column in Table 1 was formed on each steel sheet by the plating treatment method (electrogalvanizing method or hot-dip galvanizing method) shown in the "Hot-dip / Electro" column of the "Zinc-based plating layer" column in Table 1. The thickness of the zinc-based plating layer was 0.5 to 25.0 μm. "Electro" in the "Hot-dip / Electro" column means that the zinc-based plating layer was formed by electrogalvanizing method. "Hot-dip" means that the zinc-based plating layer was formed by hot-dip galvanizing method. In the following description, "%" regarding the chemical composition of the zinc-based plating layer means mass %.

[0124] In test numbers 1 to 23, a zinc-based plating layer made of Zn was formed by electrogalvanizing. Specifically, a plating bath containing zinc sulfate heptahydrate and anhydrous sodium sulfate and adjusted to a pH of 2.0 was prepared. In the electrogalvanizing, the bath temperature was set to 50°C and the current density was set to 50 A / dm ２Through the above steps, a zinc-based plating layer was formed on the steel sheet. The chemical composition of the zinc-based plating layer was analyzed based on the above-mentioned (3.2. Method for measuring the chemical composition of the zinc-based plating layer 20). As a result, the chemical composition of the zinc-based plating layer was found to be a chemical composition consisting of Zn, and the Al content was less than 0.1%. In Table 1, a zinc-based plating layer having a chemical composition consisting of Zn and an Al content of less than 0.1% is indicated as "Zn" in the "Type" column of the "Zinc-based plating layer" column in Table 1.

[0125] For test numbers 24 to 31, a Zn-10%Ni zinc-based plating layer and a Zn-14%Ni zinc-based plating layer were formed by electrogalvanizing. Specifically, a plating bath containing zinc sulfate heptahydrate, nickel sulfate hexahydrate, and anhydrous sodium sulfate, with a pH adjusted to 2.0, was prepared. For electrogalvanizing, the bath temperature was set to 50°C, and the current density and plating time were adjusted to obtain a plating composition of Zn-10%Ni or Zn-14%Ni. Through these steps, a zinc-based plating layer was formed on the steel sheet. The chemical composition of the zinc-based plating layer was analyzed based on the above-mentioned (3.2. Method for Measuring the Chemical Composition of the Zinc-Based Plating Layer 20). As a result, the chemical composition of the zinc-based plating layer for test numbers 24 to 27 was 10% Ni, with the remainder being Zn. The chemical composition of the zinc-based plating layer for test numbers 28 to 31 was 14% Ni, with the remainder being Zn. A zinc-based plating layer having a Ni content of 10% and the balance being Zn is denoted as "Zn-10Ni" in the "Type" column of the "Zinc-based plating layer" section of Table 1. A zinc-based plating layer having a Ni content of 14% and the balance being Zn is denoted as "Zn-14Ni" in the "Type" column of the "Zinc-based plating layer" section of Table 1.

[0126] For test numbers 32 to 39, a Zn-10% Fe zinc-based plating layer or a Zn-12% Fe zinc-based plating layer was formed by electrogalvanizing. Specifically, a plating bath containing zinc sulfate heptahydrate, iron sulfate heptahydrate, and anhydrous sodium sulfate, with a pH adjusted to 1.6, was prepared. For electrogalvanizing, the bath temperature was set to 50°C, and the current density and plating time were adjusted to obtain a plating composition of Zn-10% Fe or Zn-12% Fe. Through these steps, a zinc-based plating layer was formed on the steel sheet. The chemical composition of the zinc-based plating layer was analyzed based on the above-mentioned (3.2. Method for Measuring the Chemical Composition of the Zinc-Based Plating Layer 20). As a result, the chemical composition of the zinc-based plating layer for test numbers 32 to 35 was 10% Fe, with the remainder being Zn. The chemical composition of the zinc-based plating layer for test numbers 36 to 39 was 12% Fe, with the remainder being Zn. A zinc-based plating layer having an Fe content of 10% and the balance being Zn is expressed as "Zn-10Fe" in the "Type" column of the "Zinc-based plating layer" section of Table 1. A zinc-based plating layer having an Fe content of 12% and the balance being Zn is expressed as "Zn-12Fe" in the "Type" column of the "Zinc-based plating layer" section of Table 1.

[0127] For test numbers 40 to 47, a Zn-1% Co zinc-based plating layer or a Zn-2% Co zinc-based plating layer was formed by electrogalvanizing. Specifically, a plating bath containing zinc sulfate heptahydrate, cobalt sulfate heptahydrate, and anhydrous sodium sulfate, with a pH adjusted to 1.8, was prepared. For electrogalvanizing, the bath temperature was set to 50°C, and the current density and plating time were adjusted to obtain a plating composition of Zn-1% Co or Zn-2% Co. Through these steps, a zinc-based plating layer was formed on the steel sheet. The chemical composition of the zinc-based plating layer was analyzed based on the above-mentioned (3.2. Method for Measuring the Chemical Composition of the Zinc-Based Plating Layer 20). As a result, the chemical composition of the zinc-based plating layer for test numbers 40 to 43 was 1% Co, with the remainder being Zn. The chemical composition of the zinc-based plating layer for test numbers 44 to 47 was 2% Co, with the remainder being Zn. A zinc-based plating layer having a Co content of 1% and the balance being Zn is denoted as "Zn-1Co" in the "Type" column of the "Zinc-based plating layer" section of Table 1. A zinc-based plating layer having a Co content of 2% and the balance being Zn is denoted as "Zn-2Co" in the "Type" column of the "Zinc-based plating layer" section of Table 1.

[0128] In test numbers 48 and 49, a zinc-based coating layer of Zn-0.2% Al was formed by hot-dip galvanizing. Specifically, an ingot was melted to prepare a hot-dip galvanizing bath so as to have a Zn-0.2% Al coating layer. ２ -H ２ The steel sheet in which the surface oxides had been reduced in the atmosphere was immersed in a hot-dip galvanizing bath while maintaining the temperature at 20°C above the temperature of the hot-dip galvanizing bath. Furthermore, the speed at which the steel sheet was pulled up from the hot-dip galvanizing bath and the air wiping speed were adjusted so that the coating thickness would be 10 μm. Through the above steps, a zinc-based coating layer was formed on the steel sheet. The chemical composition of the zinc-based coating layer was analyzed based on the above-mentioned (3.2. Method for measuring the chemical composition of the zinc-based coating layer 20). As a result, the chemical composition of the zinc-based coating layers of test numbers 48 and 49 was found to contain 0.2% Al, with the remainder being Zn. The zinc-based coating layers with 0.2% Al and the remainder being Zn are denoted as "Zn-0.2Al" in the "Type" column of the "Zinc-based Coating Layer" section in Table 1.

[0129] In test numbers 50 to 57, a zinc-based coating layer of Zn-11.0%Al-3.0%Mg or a zinc-based coating layer of Zn-19.0%Al-6.0%Mg was formed by hot-dip galvanizing. Specifically, an ingot was melted to prepare a hot-dip galvanizing bath so as to obtain Zn-11.0%Al-3.0%Mg or Zn-19.0%Al-6.0%Mg. ２ -H ２ The steel sheets whose surface oxides had been reduced in the atmosphere were immersed in a hot-dip galvanizing bath maintained at a temperature 20°C above the bath temperature. Furthermore, the lifting speed of the steel sheets from the hot-dip galvanizing bath and the air wiping speed were adjusted so that the coating thickness would be 10 μm. Through these steps, a zinc-based coating layer was formed on the steel sheet. The chemical composition of the zinc-based coating layer was analyzed based on the above-mentioned (3.2. Method for measuring the chemical composition of the zinc-based coating layer 20). As a result, the chemical composition of the zinc-based coating layers of test numbers 50 to 53 was 11.0% Al, 3.0% Mg, and the balance Zn. The chemical composition of the zinc-based coating layers of test numbers 54 to 57 was 19.0% Al, 6.0% Mg, and the balance Zn. A zinc-based plating layer having an Al content of 11.0%, a Mg content of 3.0%, and the balance being Zn is expressed as "Zn-11.0Al-3.0Mg" in the "Type" column of the "Zinc-based plating layer" section of Table 1. A zinc-based plating layer having an Al content of 19.0%, a Mg content of 6.0%, and the balance being Zn is expressed as "Zn-19.0Al-6.0Mg" in the "Type" column of the "Zinc-based plating layer" section of Table 1.

[0130] [Texture Forming Step] Hairlines were formed on the surfaces of the plated steel sheets of each test number by hairline processing. The hairline processing was carried out using an abrasive brush under the same conditions for each test number.

[0131] [Primer layer forming step] A primer layer was formed on the surface of the zinc-based plating layer on which the hairline had been formed, using a primer layer composition paint having a composition shown in the "Paint type" column of the "Primer layer" column in Table 1. Each primer layer composition paint is shown in Table 2.

[0132]

[0133] The "Binder" column in Table 2 indicates the type of binder. The "Type" column in the "First Inorganic Component" column indicates the elements in the compound contained in the first inorganic component. For example, a primer layer composition paint of paint type I contains urethane as the binder and a phosphate compound (P) and a Zr compound (Zr) as the first inorganic component. The "Compound Concentration (% by mass)" column in the "First Inorganic Component" column indicates the content (% by mass) of the first inorganic component when the total content of the primer layer composition paint (binder and first inorganic component) is taken as 100% by mass. The "Total Concentration of Target Element (% by mass)" column indicates the concentration (% by mass) of the target element in the first inorganic component when the total content of the primer layer composition paint (binder and first inorganic component) is taken as 100% by mass.

[0134] The primer layer composition paint was applied to the plated steel sheet using a coater and then dried in a baking oven. The maximum temperature PMT of the baking oven was in the range of 150 to 250°C. A primer layer was formed through the above steps.

[0135] [Organic Resin Layer Forming Step] After forming the primer layer, an organic resin layer was formed on the surface of the primer layer using an organic resin layer composition paint having a composition shown in the "Paint Type" column of the "Organic Resin Layer" column in Table 1. Each organic resin layer composition paint is shown in Table 3.

[0136]

[0137] In Table 3, the "Base resin" column shows the base resin component contained in the organic resin layer composition paint. The "Fluorine-based resin type" column shows the type of fluorine-based resin contained. A "-" in the "Fluorine-based resin type" column indicates that no fluorine-based resin was contained. The "Non-fluorine-based resin type" column shows the type of organic resin other than the fluorine-based resin contained in the base resin. The "Fluorine-based resin ratio (mass %)" column shows the content (mass %) of fluorine-based resin when the total content of the base resin components is taken as 100 mass %.

[0138] The "Second Inorganic Component" column in Table 3 shows the type and concentration (% by mass) of the second inorganic component contained in the organic resin layer composition paint. The "Type" column in the "Second Inorganic Component" column shows the element of the compound contained as the second inorganic component. For example, "Ti" for paint type A means that a Ti compound is contained as the second inorganic component. The "Concentration (% by mass)" column in the "Second Inorganic Component" column shows the total concentration (% by mass) of the target element of the second inorganic component when the total content of the base resin, second inorganic component, and pigment in the organic resin layer composition paint is taken as 100% by mass. A "-" in the "Second Inorganic Component" column indicates that the second inorganic component was not contained.

[0139] The "Concentration (mass %)" column in the "Pigment" column in Table 3 shows the pigment content (mass %) when the total content of the base resin, second inorganic component, and pigment in the organic resin layer composition paint is taken as 100% by mass. Note that "-" indicates that no pigment was contained. The pigment contained in all paint types was carbon black.

[0140] The organic resin layer composition paint was applied to the plated steel sheet using a coater, and then dried in a baking oven. The maximum temperature PMT of the baking oven was in the range of 150 to 250°C. By the above process, the organic resin layer was formed. By the above manufacturing process, the decorative steel sheet of each test number was manufactured.

[0141] [Evaluation Tests] The following evaluation tests were carried out on the plated steel sheets with each test number: (Test 1) Measurement test of the content of the second inorganic component in elemental equivalent (Test 2) Measurement test of the inorganic component ratio ICR (Test 3) Measurement test of the film thickness in elemental equivalent ET (Test 4) Measurement test of the thickness of the primer layer and the organic resin layer (Test 5) Evaluation test of corrosion resistance (Test 6) Evaluation test of weather resistance (Test 7) ​​Evaluation test of texture design Tests 1 to 7 are described below.

[0142] [(Test 1) Measurement of the content of the second inorganic component in terms of element] ２ The elemental content (g / m) of the second inorganic component in the organic resin layer of each test number was measured in accordance with the method described in the measurement method for the second inorganic component. ２The obtained content (g / m) of the second inorganic component in terms of element was measured. ２ ) in the "organic resin layer" column in Table 1. ２ ) column.

[0143] [(Test 2) Inorganic Component Ratio ICR Measurement Test] The inorganic component ratio ICR of the decorative steel sheet of each test number was determined according to the method described above in (6.1. Method for measuring inorganic component ratio ICR). The obtained inorganic component ratio ICR is shown in the "Inorganic Component Ratio ICR" column in Table 1. The obtained element-equivalent content (g / m) of the first inorganic component was ２ ) in the "primer layer" column in Table 1. ２ ) shown below.

[0144] [(Test 3) Measurement of Equivalent Elemental Thickness ET] According to the method described above in (4.3.1. Measurement Method of Equivalent Elemental Thickness ET), the equivalent elemental thickness (μm) of the first inorganic component for each test number was determined. The obtained equivalent elemental thickness (μm) is shown in the "Equivalent Elemental Thickness ET (μm)" column of the "Primer Layer" column in Table 1.

[0145] [(Test 4) Thickness Measurement Test of Primer Layer and Organic Resin Layer] The thickness of the primer layer of the decorative steel sheet of each test number was determined according to the method described above in (4.3.1. Method for Measuring Equivalent Elemental Film Thickness ET). The obtained thickness (μm) of the primer layer is shown in the "Thickness (μm)" column of the "Primer Layer" column in Table 1. In addition, the thickness (μm) of the primer layer of the decorative steel sheet of each test number was measured according to the method described above in (5.3.1. Method for Measuring Equivalent Elemental Film Thickness (g / m)). ２ The thickness of the organic resin layer of the decorative steel sheet of each test number was determined in accordance with the method described in "Measurement method for thickness of the organic resin layer." The obtained thickness (μm) of the organic resin layer is shown in the "Thickness (μm)" column of the "Organic resin layer" column in Table 1.

[0146] [(Test 5) Corrosion Resistance Evaluation Test] The corrosion resistance (long-term corrosion resistance) of the decorative steel plate of each test number was evaluated by the following method. A 75 mm × 100 mm test specimen was taken from each decorative steel plate of each test number. The end faces and back faces of the test specimen were protected with tape seals. Then, a salt spray test of 5% NaCl maintained at 35°C was conducted in accordance with JIS Z 2371 (2015). The test was conducted for 240 hours, and the rust occurrence rate (%) after the test was calculated. The obtained rust occurrence rate was evaluated as follows: A: The rust occurrence rate was less than 1%. B: The rust occurrence rate was 1% or more but less than 5%. C: The rust occurrence rate was 5% or more. A rating of A or B was evaluated as excellent corrosion resistance. A rating of C was evaluated as insufficient corrosion resistance. The evaluation results are shown in the "Corrosion Resistance" column in Table 1.

[0147] [(Test 6) Weather Resistance Evaluation Test] An accelerated weather resistance test was conducted on the decorative steel sheets of each test number in accordance with JIS K 5600-7-8 (1999) (ultraviolet fluorescent lamp method). The evaluation was conducted in accordance with JIS K 5600-4-7 (1999) (specular glossiness). Specifically, the gloss retention (%) was calculated as the ratio of the gloss after 1000 hours of testing, with the gloss immediately before the start of the test taken as 100%. Weather resistance was evaluated based on the obtained gloss retention according to the following criteria: A: The gloss retention was 80% or more. B: The gloss retention was 60% or more but less than 80%. C: The gloss retention was less than 60%. A rating of A or B was evaluated as excellent weather resistance being obtained. A rating of C was evaluated as insufficient weather resistance being obtained. The evaluation results are shown in the "Weather Resistance" column in Table 1.

[0148] [(Test 7) ​​Texture Design Evaluation Test] The texture design of the decorative steel sheets of each test number was evaluated using the following method. First, the decorative steel sheets of each test number were installed outdoors at an angle of 60° to the horizontal. The decorative steel sheets were installed so that the zinc-based plating layer faced upward outdoors. Next, an observer visually observed the decorative steel sheets from a location 1 m away from the location where the decorative steel sheets were installed on the ground, facing the decorative steel sheets. The observers' line of sight was at the same height as the decorative steel sheets. A total of 10 observers visually observed the decorative steel sheets and performed a sensory evaluation to determine whether the decorative steel sheets were excellent in design. The following evaluation was performed based on the number of observers who judged the decorative steel sheets to be excellent in design. A: Eight or more observers judged the decorative steel sheets to be excellent in design. B: Five or more but less than eight observers judged the decorative steel sheets to be excellent in design. C: Less than five observers judged the decorative steel sheets to be excellent in design. A rating of A or B was determined to indicate that excellent design was obtained. When the evaluation was C, it was evaluated that sufficient design was not obtained. The evaluation results are shown in the "Texture design" column in Table 1.

[0149] [Evaluation Results] Referring to Tables 1 to 3, in test numbers 1 to 15 and 23 to 57, the compositions of the primer layer and the organic resin layer were appropriate, the elemental equivalent film thickness ET of the first inorganic component in the primer layer was 0.0070 μm or more, and the elemental equivalent content of the second inorganic component was 0 to 0.0150 g / m ２ and the inorganic component ratio ICR was 0.7 or less. Therefore, the texture TX was visible in the decorative steel sheets of these test numbers. Furthermore, the decorative steel sheets of these test numbers obtained excellent corrosion resistance and excellent weather resistance, and also obtained excellent design properties.

[0150] In particular, in test numbers 4, 9, 10 and 23 to 57, the ratio of the fluorine-based resin in the base resin was appropriate, the thickness of the organic resin layer was 2.30 to 8.00 μm, and the content of the second inorganic component in terms of element was 0.0085 g / m ２ The thickness ET of the first inorganic component in the primer layer in terms of element was 0.0125 to 0.2000 μm. Therefore, the decorative steel sheets having these test numbers were remarkably excellent in corrosion resistance, light resistance, and decorativeness.

[0151] In test number 1, the thickness of the organic resin layer was less than 2.30 μm, and therefore the corrosion resistance was evaluated as B.

[0152] In test numbers 2 and 5, the thickness of the organic resin layer exceeded 8.00 μm, and therefore the design was evaluated as B.

[0153] In test number 3, the ratio of fluorine-based resin in the base resin was high. Therefore, the corrosion resistance was evaluated as B. In addition, the content of the second inorganic component in terms of element was 0.0085 g / m ２ Therefore, the design was rated B.

[0154] In test number 6, the content of the pigment in the organic resin layer was high. Therefore, the design evaluation was B. In addition, the thickness of the organic resin layer was less than 2.30 μm. Therefore, the corrosion resistance evaluation was B.

[0155] In test numbers 7 and 8, the elemental content of the second inorganic component was 0.0085 g / m ２ Therefore, the design evaluation was B.

[0156] In test number 11, the equivalent elemental film thickness ET of the first inorganic component in the primer layer was less than 0.0125 μm. Therefore, the corrosion resistance evaluation was B. In addition, the equivalent elemental content of the second inorganic component was 0.0085 g / m ２ Therefore, the design was rated B.

[0157] In test number 12, the equivalent element thickness ET of the first inorganic component in the primer layer was less than 0.0125 μm, and the thickness of the organic resin layer was less than 2.30 μm. Therefore, the corrosion resistance evaluation was B.

[0158] In test number 13, the equivalent element thickness ET of the first inorganic component in the primer layer was less than 0.0125 μm, and therefore the corrosion resistance was evaluated as B.

[0159] In test number 14, the equivalent element thickness ET of the first inorganic component in the primer layer exceeded 0.2000 μm, and therefore the design was evaluated as B.

[0160] In test number 15, the equivalent element thickness ET of the first inorganic component in the primer layer was less than 0.0125 μm, and therefore the corrosion resistance was evaluated as B.

[0161] On the other hand, in test number 16, the organic resin layer 40 did not contain a fluorine-based resin. Therefore, sufficient weather resistance was not obtained. Furthermore, the content of the second inorganic component in terms of element was too high. Therefore, sufficient design properties were not obtained.

[0162] In test number 17, the organic resin layer 40 did not contain a fluorine-based resin, and therefore sufficient weather resistance was not obtained.

[0163] In test number 18, the equivalent element thickness ET was too low, and the inorganic component ratio ICR was too high, so sufficient corrosion resistance was not obtained.

[0164] In test number 19, the content of the second inorganic component in terms of element was too high. As a result, the inorganic component ratio ICR was also too high. Therefore, sufficient design properties were not obtained.

[0165] In test number 20, the content of the second inorganic component in terms of element was too high, and therefore sufficient design properties were not obtained.

[0166] In test number 21, the inorganic component ratio ICR was too high, and therefore sufficient corrosion resistance was not obtained.

[0167] In test number 22, the elemental equivalent film thickness ET was too low, and therefore sufficient corrosion resistance was not obtained.

[0168] The embodiments of the present disclosure have been described above. However, the above-described embodiments are merely examples for implementing the present disclosure. Therefore, the present disclosure is not limited to the above-described embodiments, and can be implemented by appropriately modifying the above-described embodiments within the scope of the present disclosure.

[0169] REFERENCE SIGNS LIST 1: Design steel material 10: Steel material 20: Zinc-based plating layer 30: Primer layer 40: Organic resin layer

Claims

Steel and a zinc-based plating layer formed on the surface of the steel material, the zinc-based plating layer having a texture formed on the surface; a primer layer formed on the surface of the zinc-based plating layer; an organic resin layer formed on the surface of the primer layer, The primer layer is Binder and a first inorganic component; The organic resin layer is a base resin containing a fluorine-based resin; 0 to 0.0150 g / m in elemental terms ２ and a second inorganic component, the film thickness of the first inorganic component in the primer layer is 0.0070 μm or more in terms of element; an inorganic component ratio, which is the ratio of the content of the second inorganic component in the organic resin layer in elemental terms to the content of the first inorganic component in the primer layer in elemental terms, is 0.7 or less; Design steel. 　 The decorative steel material according to claim 1, The first inorganic component of the primer layer is a specific compound containing one or more selected from the group consisting of Ti and Zr; a phosphate compound, V compound, Design steel. 　 The decorative steel material according to claim 1, the second inorganic component contains a Group 4A metal compound; Design steel. 　 The decorative steel material according to claim 1, The base resin further contains a melamine resin. Design steel. 　 The decorative steel material according to any one of claims 1 to 4, The zinc-based plating layer is made of Zn—Ni alloy plating. Design steel.

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