Surface-treated steel material

Abstract

Provided is a surface-treated steel material having high corrosion resistance and high heat resistance. A surface-treated steel material according to the present invention is obtained by arranging a steel material, a Zn-containing plating layer, and a coating, in this order. The coating contains trivalent Cr, an organosilicon compound, and a resin. The trivalent Cr concentration in the coating is 0.30-20.00 mass%. In the coating, a peak indicating an amino group is detected at both 3500-3300 cm-1 and 1650-1580 cm-1, as measured by a Fourier transform infrared spectrometer (FT-IR).

Description

Surface-treated steel

[0001] This invention relates to surface-treated steel materials.

[0002] Zinc-based plating layers, formed from zinc or zinc-containing alloys, are known to improve the corrosion resistance of steel materials. To further enhance the corrosion resistance and resistance to blackening of the zinc-based plating layer, an inorganic film may be formed on the surface of the zinc-based plating layer.

[0003] For example, Patent Documents 1 and 2 describe forming a film containing trivalent chromium (Cr) on the surface of a zinc-based plating layer. Patent Documents 1 and 2 also describe that the film containing trivalent Cr improved the corrosion resistance of flat plates and processed parts.

[0004] International Publication No. 2023 / 121175, JP 2024-505793

[0005] Patent documents 1 and 2 describe that the corrosion resistance of steel sheets having a zinc-based plating layer is improved by a coating containing trivalent chromium. However, according to the inventors' findings, the corrosion resistance of steel materials does not always improve even when a coating containing trivalent chromium is used. Furthermore, forming a coating containing trivalent chromium sometimes increases the sliding coefficient of the coated surface of the steel material. Heat resistance is also required for surface-treated steel materials.

[0006] In view of these circumstances, the present invention aims to provide a surface-treated steel material that has high corrosion resistance, suppresses an increase in the sliding coefficient of the surface on which the coating is formed, and also has high heat resistance.

[0007] One aspect of the present invention for solving the above problems relates to the following surface-treated steel materials [1] to [9]. [1] A surface-treated steel material comprising a steel material, a plating layer containing Zn, and a film arranged in this order, wherein the film contains trivalent Cr, an organosilicon compound, and a resin, the concentration of trivalent Cr in the film is 0.30% by mass or more and 20.00% by mass or less, and the film has a temperature of 3500 to 3300 cm² as measured using a Fourier transform infrared spectrophotometer (FT-IR). －１ and 1650-1580 cm －１[1] A surface-treated steel material in which peaks indicating amino groups are detected in both. [2] The surface-treated steel material according to [1], wherein the peak indicating amino groups is a peak derived from the organosilicon compound. [3] The surface-treated steel material according to [1] or [2], wherein the film contains Zr. [4] The surface-treated steel material according to any one of [1] to [3], wherein the mass concentration ratio (Cr / Si) of the trivalent Cr to the Si derived from the organosilicon compound in the film is 0.050 or more and 2.600 or less. [5] The surface-treated steel material according to any one of [1] to [4], wherein the film contains P or V. [6] The surface-treated steel material according to any one of [1] to [5], wherein the film contains Co. [7] The surface-treated steel material according to any one of [1] to [6], wherein the resin is at least one resin selected from the group consisting of acrylic resin, epoxy resin, urethane resin, polyester resin, and phenolic resin. [8] The surface-treated steel material according to any one of [1] to [7], wherein the film has a thickness of 0.250 μm or more and 10.00 μm or less. [9] The surface-treated steel material according to any one of [1] to [8], wherein the plating layer has an Al content of 1.0% by mass or more and 22.0% by mass or less, an Mg content of 1.5% by mass or more and 10.0% by mass or less, and the remainder consists of Zn and optionally added trace additives.

[0008] According to the present invention, a surface-treated steel material is provided that has high corrosion resistance, suppresses the increase in the sliding coefficient of the surface on which the coating is formed, and also has high heat resistance.

[0009] An embodiment of the present invention will be described below.

[0010] 1. Surface-treated steel material The surface-treated steel material according to this embodiment has a steel material, a plating layer, and a coating arranged in this order.

[0011] 1-1. The type of steel used as the base material is not particularly limited and may be any type of steel, such as steel plates, steel bars, H-beams, I-beams, wire rods, building hardware, or steel pipes. For example, as steel plates, any type of steel can be used, including hot-rolled mild steel plates and strips as described in JIS G 3131 (2018), hot-rolled steel plates and strips for automobiles as described in JIS G 3113 (2018), cold-rolled steel plates and strips as described in JIS G 3141 (2017), and various types of stainless steel plates (including austenitic, martensitic, ferritic, and ferritic-martensitic duplex types).

[0012] 1-2. Plating Layer The plating layer is a plating layer containing zinc (Zn). Preferably, the plating layer is a plating layer mainly composed of Zn. Note that "mainly composed of Zn" means that the plating layer contains 50% by mass or more of Zn. The plating layer may be a plating layer manufactured by any method such as electroplating, hot-dip plating, or vapor deposition plating. The plating layer may be a Zn plating layer, or it may be a plating layer made of an alloy containing Zn (for example, alloys such as Zn-Al, Zn-Mg, Zn-Ni, Zn-Al-Mg, etc.).

[0013] For example, the plating layer may contain 1.0% by mass or more and 22.0% by mass or less of aluminum (Al). Al acts as a passivator, improving the corrosion resistance of the plating layer and suppressing the generation of dross during manufacturing. By setting the Al content to 1.0% by mass or more, the corrosion resistance of the plating layer can be sufficiently improved and the generation of dross can be sufficiently suppressed. By setting the Al content to 22.0% by mass or less, a decrease in the adhesion of the plating layer can be suppressed and a decrease in the sacrificial corrosion protection effect by Zn can be suppressed. Preferably, the Al content is 12.0% by mass or more and 20.0% by mass or less.

[0014] Furthermore, the plating layer may contain 1.5% by mass or more and 10.0% by mass or less of magnesium (Mg). Mg uniformly generates dense corrosion products on the surface of the plating layer, preventing erosion by corrosive factors and improving the corrosion resistance of the plating layer. By setting the Mg content to 1.5% by mass or more, sufficient dense and uniform corrosion products can be generated, thereby sufficiently improving the corrosion resistance of the plating layer. By setting the Mg content to 10.0% by mass or less, the reduction in the sacrificial corrosion protection effect by Zn can be suppressed, and the generation of dross can also be suppressed. The Mg content is preferably 2.0% by mass or more and 8.5% by mass or less, and more preferably 4.0% by mass or more and 7.0% by mass or less.

[0015] Furthermore, when the plating layer contains Al, silicon (Si) may be included in a range of 0.005% to 2.0% by mass to improve adhesion between the steel material and the plating layer, thereby suppressing the growth of the Fe-Zn alloy layer and Fe-Al alloy layer at the interface between the steel material and the plating layer. In addition, when the plating layer contains Mg, Zn may be included to avoid adverse effects on appearance and corrosion resistance. １１ Mg ２ To suppress the formation and growth of phases, titanium (Ti), boron (B), Ti-B alloys, Ti-containing compounds, or B-containing compounds may be included. Preferably, the content of these compounds is in the range of 0.001% by mass or more and 0.1% by mass or less for Ti, and in the range of 0.0005% by mass or more and 0.045% by mass or less for B.

[0016] Furthermore, the plating layer may contain trace amounts of additives and unavoidable impurities in addition to Zn. Trace amounts of additives are, for example, elements added to improve the corrosion resistance of the plating layer. Trace amounts of additives can be elements such as Sn, Bi, In, Ca, Y, La, Ce, Si, Cr, Ti, Ni, Co, V, Nb, Cu, Mn, Fe, Sr, Sb, Pb, B, Li, Zr, Mo, W, Ag, and P. The content of these trace amounts can be between the detection limit and 1% by mass.

[0017] The type and content of elements contained in the plating layer are measured by inductively coupled plasma analysis (ICP analysis). Specifically, the coating film is removed with a known coating film remover at a position that is 30 mm or more away from the end portion toward the inner surface side, and when processing such as welding or bending has been performed, at a position 30 mm or more away from the processed portion. After washing the exposed surface, the plating layer is dissolved in hydrochloric acid. By performing ICP analysis on the solution in which the plating layer is dissolved, the type and content of elements contained in the plating layer can be identified.

[0018] 1-3. Coating Film The coating film is a film formed by surface treatment on the surface of the plating layer.

[0019] In the present embodiment, the coating film contains trivalent chromium (Cr), an organosilicon compound, and a resin.

[0020] For example, the organosilicon compound can be a molecule in which an organic functional group and a hydrolyzable functional group are bonded to a silicon molecule. The organic functional group is an organic reactive group such as an amino group, an epoxy group, a (meth)acryloyl group, a vinyl group, and a mercapto group, and the hydrolyzable functional group is a functional group such as an alkoxy group. The organic functional group may be bonded to the silicon molecule via an alkylene group, an oxyalkylene group, or the like.

[0021] The organosilicon compound forms a crosslinked structure in the coating film to enhance the adhesion of the coating film to the plating layer. In the present embodiment, it is further believed that trivalent Cr dispersed in the coating film reacts or interacts with the organosilicon compound to form a denser coating film structure, which improves the barrier property of the coating film and thereby enhances the corrosion resistance of the surface-treated steel material. In addition, since trivalent Cr has low toxicity, it is considered that problems such as adverse effects on the human body and environmental pollution do not occur.

[0022] The concentration of trivalent Cr in the coating is 0.30% by mass or more and 20.00% by mass or less. By setting the concentration of trivalent Cr to 0.30% by mass or more, it is easier to form the dense coating structure described above, and the corrosion resistance of the surface-treated steel can be improved by improving the barrier properties. By setting the concentration of trivalent Cr to 20.00% by mass or less, it is possible to suppress the increase in the sliding coefficient due to the aggregation of trivalent Cr. From the viewpoint of balancing these, the concentration of trivalent Cr in the coating is preferably 0.50% by mass or more and 15.0% by mass or less, more preferably 1.00% by mass or more and 10.00% by mass or less, and even more preferably 1.50% by mass or more and 3.50% by mass or less.

[0023] The film thickness was measured by FT-IR at 3500–3300 cm². －１ (N-H coupling, stretching vibration) and 1650–1580 cm －１ Peaks indicating amino groups are detected in both the N-H bond and the bending vibration. The film containing amino groups forms a network of amino groups, which can improve the corrosion resistance of surface-treated steel materials.

[0024] The peak indicating the amino group can, for example, be a peak derived from an organosilicon compound containing an amino group. In this case, it is preferable to use a silane coupling agent containing one or more amino groups as the organosilicon compound. It is thought that in a silane coupling agent containing an amino group, the inorganic structural part with a siloxane bond as its backbone forms a network of -Si-O- bonds through a dehydration condensation reaction, and at the same time, the organic structural part having an amino group forms a network through the reaction of the amino group. This multi-layered network structure is thought to make the film structure denser, improving barrier properties and increasing the corrosion resistance of the surface-treated steel material.

[0025] The film containing the above organosilicon compound was measured using a Fourier transform infrared spectrophotometer (FT-IR) at 1100–1000 cm². －１ A peak is observed at (Si-O (siloxane bond)). 1100-1000 cm －１ The peak area of ​​the detected peak (peak derived from siloxane binding) is 1650–1580 cm².－１ The peak area ratio of the detected peak (amino group-derived peak) (amino group-derived peak / siloxane bond-derived peak) is preferably 0.030 or more and 0.800 or less, more preferably 0.200 or more and 0.600 or less. Setting the peak area ratio to 0.200 or more results in a dense film structure. Setting the peak area ratio to 0.600 or less can suppress the decrease in corrosion resistance caused by an excess of highly hydrophilic amino groups.

[0026] The concentration of Si derived from the organosilicon compound is preferably 2.00% by mass or more and 30.00% by mass or less. Setting the Si concentration to 2.00% by mass or more allows a siloxane bond network to be formed throughout the entire film. Further, the Si concentration is more preferably 5.00% by mass or more and 20.00% by mass or less, and even more preferably 10.00% by mass or more and 20.00% by mass or less. The higher the concentration of Si derived from the organosilicon compound, the higher the fingerprint resistance of the surface-treated steel material. On the other hand, setting the Si concentration to 30.00% by mass or less, preferably 20.00% by mass or less, allows the film to have appropriate flexibility, thereby improving the workability (bendability) of the surface-treated steel material.

[0027] The resin may be a thermosetting resin or a thermoplastic resin. Thermosetting resins have high heat resistance. Further, thermoplastic resins enhance the thermal dispersion of the film through the free movement of the molecular skeleton, thereby improving the heat resistance of the film. Through these effects, the resin enhances the heat resistance of the film. Examples of the resin include acrylic resins, epoxy resins, urethane resins, polyester resins, and phenolic resins. Among these, polyester resins and polyurethane resins are preferable from the viewpoint of workability.

[0028] The thermoplastic resin preferably has a glass transition temperature (Tg) measured by DSC (differential scanning calorimetry) of -10°C or higher and 120°C or lower, more preferably 0°C or higher and 100°C or lower, and even more preferably 10°C or higher and 80°C or lower. When the glass transition temperature is within the above range, the molecular mobility tends to increase when the surface-treated steel sheet is heated, and the heat resistance of the film tends to improve.

[0029] The resin content in the coating is preferably 0.50% by mass or more and 80.0% by mass or less, more preferably 5.0% by mass or more and 45.0% by mass or less, and even more preferably 30.0% by mass or more and 40.0% by mass or less. The higher the resin content, the higher the heat resistance of the coating tends to be.

[0030] The coating preferably contains zirconium (Zr). Zr forms a cross-linking structure in the coating, improving the adhesion of the coating to the plating layer and making the coating structure denser, thereby improving barrier properties and further enhancing the corrosion resistance of the surface-treated steel material. In this embodiment, the combined use of trivalent Cr and zirconium significantly enhances the corrosion resistance improvement effect of zirconium. This is thought to be because both trivalent Cr and zirconium are incorporated into the bonding of the organosilicon compound, making the coating structure very dense. Furthermore, Zr also makes it less likely for the coating to peel off due to water.

[0031] The amount of Zr in the coating is preferably 0.10% by mass or more and 20.00% by mass or less, and more preferably 1.00% by mass or more and 10.00% by mass or less, relative to the total mass of the coating. By setting it within the above range, the adhesion between the plating layer and the coating can be further improved, and the corrosion resistance of the surface-treated steel material can be further enhanced.

[0032] Furthermore, the mass concentration ratio (Cr / Zr) of trivalent Cr to Zr in the coating is preferably 0.50 or more and 7.00 or less, and more preferably 1.50 or more and 7.00 or less. The higher the Cr / Zr ratio, the more likely it is that a denser coating structure will result in improved barrier properties. The lower the Cr / Zr ratio, the less Cr is present, and the less likely Cr aggregates are to form in the coating. This makes it less likely for Cr to be unevenly distributed in the coating, improving the sliding properties of the coating.

[0033] Furthermore, the mass concentration ratio (Cr / Si) of trivalent Cr to Si derived from organosilicon compounds in the coating is preferably 0.050 to 2.600. The higher the Cr / Si ratio, the easier it is to improve barrier properties due to a denser coating structure. The lower the Cr / Si ratio, the less Cr is present, and the less likely Cr aggregates are to form in the coating. When Cr aggregates form, localized hard protrusions are formed on the surface and inside the coating, increasing microscopic irregularities and reducing the sliding properties of the coating. Therefore, the lower the Cr / Si ratio, the less likely Cr is to be unevenly distributed in the coating, improving the sliding properties of the coating. Also, the lower the Cr / Si ratio, the relatively larger the amount of organosilicon compounds can be, improving the fingerprint resistance of the surface-treated steel material. From the viewpoint of balancing these factors, it is more preferable that the Cr / Si ratio is 0.100 to 1.500, and even more preferable that it is 0.500 to 0.650.

[0034] Furthermore, the coating preferably contains phosphorus (P) or vanadium (V). These elements, like Zr, enhance the corrosion resistance of the coating and can also make the coating structure denser, making it less susceptible to peeling due to water. The coating may contain P and V individually, or both. From the viewpoint of more effectively utilizing the corrosion resistance-enhancing effect of these elements and the water resistance-enhancing effect due to the densification of the coating, it is preferable that the coating contains both P and V.

[0035] P enhances the adhesion of the film to the plating layer, thereby improving the corrosion resistance of surface-treated steel materials.

[0036] P is typically included in the film as phosphoric acid or a salt thereof. Examples of phosphoric acid or salts thereof include phosphoric acids or salts thereof such as orthophosphate, metaphosphate, pyrophosphate, triphosphate, and tetraphosphate (for example, ammonium salts such as triammonium phosphate and diammonium hydrogen phosphate), phosphonic acids or salts thereof such as aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra(methylenephosphonic acid), and diethylenetriaminepenta(methylenephosphonic acid), as well as organic phosphoric acids or salts thereof such as phytic acid. In addition to ammonium salts, metal salts with Na, Mg, Al, K, Ca, Mn, Ni, Zn, and Fe may also be used. These phosphoric acids or salts thereof may be used individually or in combination of two or more.

[0037] The amount of phosphorus (P) in the coating is preferably 0.10% by mass or more and 25.00% by mass or less, and more preferably 1.00% by mass or more and 15.00% by mass or less, relative to the total mass of the coating. By setting the amount within the above range, the adhesion between the plating layer and the coating can be further improved, and the corrosion resistance of the surface-treated steel material can be further enhanced.

[0038] V functions as an inhibitor, forming a precipitated film or passivation film, thereby further enhancing the corrosion resistance of surface-treated steel materials.

[0039] The amount of V in the coating is preferably 0.10% by mass or more and 20.00% by mass or less, and more preferably 1.0% by mass or more and 10.0% by mass or less, relative to the total mass of the coating. By setting it within the above range, the corrosion resistance of the surface-treated steel material can be further improved.

[0040] Furthermore, the coating preferably contains cobalt (Co).

[0041] Co can suppress discoloration of plated steel sheets, and is particularly effective in suppressing blackening. The Co can be either divalent or trivalent.

[0042] The amount of Co in the coating is preferably 0.01% by mass or more and 10.00% by mass or less, and more preferably 0.10% by mass or more and 5.00% by mass or less, relative to the total mass of the coating. By keeping it within the above range, the resistance to blackening of the surface-treated steel material can be effectively enhanced.

[0043] The coating may contain elements such as titanium (Ti), niobium (Nb), tantalum (Ta), and tungsten (W). The coating may also contain silica particles or fluorides. The amount of these elements or additives in the coating is preferably 0.01% by mass or more and 3.00% by mass or less, and more preferably 0.01% by mass or more and 2.00% by mass or less, relative to the total mass of the coating.

[0044] The amount of these elements in the coating is measured by inductively coupled plasma analysis (ICP analysis). Specifically, the coating is scraped off with a scrubber at a position at least 30 mm away from the edge of the plated steel sheet toward the inner surface, and at least 30 mm away from the processed area if welding or bending has been performed. The area to be scraped off can be, for example, 3 cm wide and 3 cm long, but the area may be widened to obtain a sufficient sample amount when the coating is thin. By performing ICP analysis on the scraped coating, the types and amounts of elements contained in the coating can be identified.

[0045] The valency of Cr is measured by X-ray photoelectron spectroscopy (XPS) on films collected from the same range. For XPS measurements, mono-Al Kα (hν: 1486.6 eV) is used as the X-ray source. If the detected peak top position is between 576 and 578 eV, it is determined to be trivalent Cr; if it is between 579 and 580 eV, it is determined to be hexavalent Cr.

[0046] For Si, the measurement range was 1100–1000 cm using a Fourier transform infrared spectrophotometer (FT-IR) with total internal reflection (ATR). －１ (Siloxane bond), 1500–1300 cm －１ (C-H bond, Si-CH ３ (Bending vibration of the coupling), 900-800 cm －１ (Si-CH ３Confirm that absorption peaks are detected in all of the bond stretching vibrations. Furthermore, confirm that this Si originates from an organosilicon compound and not silica or silicone resin. Specifically, for samples obtained by scraping the film with a scrubber, ２９ Solid-state nuclear magnetic resonance measurements targeting Si show a peak (T peak) at -40 to -80 ppm indicating a silanol group (Tn structure) with a Si-C bond, and SiO ４ The peak (Q peak) in the -90 to -120 ppm range, which indicates a (Qn structure), and the peak area ratio (T peak / Q peak) are measured. When this peak area ratio is 6 / 4 to 9 / 1, that is, when the T peak has a larger peak area than the Q peak, which is characteristic of silica or silicone resin, it is determined that there is almost no silica or silicone resin in the film, and the detected Si is derived from an organosilicon compound.

[0047] Furthermore, for organosilicon compounds containing an amino group, total internal reflection (ATR) was measured using a Fourier transform infrared spectrophotometer (FT-IR) at 3500–3300 cm⁻¹. －１ (NH bond, stretching vibration), 1650-1580cm －１ When absorption peaks are detected in either the N-H bond or the bending vibration, it is determined that an amino group derived from an organosilicon compound is present in the film.

[0048] In this embodiment, the total internal reflection (ATR) method is performed under the following measurement conditions: • ATR crystal: Diamond (or Ge) • Measurement mode: ATR single reflection • Measurement wavenumber range: 4000-650 cm －１ ・Resolution: 4cm －１ • Number of cumulative measurements: 32 • Background: Atmospheric background acquired immediately before measurement • Light source: Mid-infrared light source (Glover) • Detector: DTGS • Sample contact: Measurement performed with constant pressure using an ATR head • Measurement position: Any point at least 30 mm away from the edge of the test piece

[0049] Furthermore, the peak area ratio in this embodiment is measured using the obtained spectrum under the following conditions: • Baseline processing: Linear baseline method • Area calculation method: Wavenumber integral (1650–1580 cm²) －１ / 1100-1000cm －１ )

[0050] Furthermore, the mass spectrum of secondary ions emitted from the film surface is measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS). When resins containing amino groups are present, fragment ions containing amino groups are detected, but those derived from the silane coupling agent and those derived from the resin can be distinguished by the difference in mass. That is, from the component derived from the silane coupling agent, Si-(CH4) ２ ) ｘ -NH ２ Fragment ions containing silicon atoms and amino groups, corresponding to this, are observed. On the other hand, from resins containing amino groups, C ｙ H ｚ N ＋ A silicon-free polymeric fragment ion, represented by [the formula shown], is observed. This resin-derived fragment ion has a larger mass than the fragment ion derived from the silane coupling agent, and is therefore clearly separated and detected on the mass spectrum. The absence of this silicon-free polymeric fragment ion confirms that the N-H bond absorption peak identified by the FT-IR analysis originates from an organosilicon compound containing an amino group.

[0051] The film thickness is preferably 0.250 μm or more and 10.00 μm or less. The thinner the film thickness, the less likely the film is to peel off during processing, and the corrosion resistance of the processed area can be improved. The thicker the film thickness, the higher the heat resistance of the film can be improved. From the above viewpoint, the film thickness is preferably 0.5 μm or more and 7.00 μm or less, and more preferably 0.80 μm or more and 6.00 μm or less.

[0052] The film thickness is measured by cutting a 40 μm × 10 μm test piece from the surface-treated steel material using the cryo-FIB method, cutting it in the thickness direction of the steel material (perpendicular to the surface of the steel plate) in a plan view. When cutting the test piece from the component, it should be cut at a location at least 30 mm away from bends and welds. The cut cross section is observed using a transmission electron microscope (TEM) at a magnification (100,000 to 1,000,000x) where the entire film and a portion of the plating layer are visible in the field of view. The acceleration voltage for this observation is 200 kV. The film observed at the topmost outer edge of the plating layer when observed with FE-TEM is identified as the film formed as described above. The boundary between the film and the plating layer can be easily identified from the observation image by a person skilled in the art. In this way, the distance from the boundary between the film and the plating layer to the surface of the film is measured as the film thickness. The film thickness is measured at three points parallel to the steel surface, with measurement intervals varying by 10 μm, and the average value is taken as the film thickness.

[0053] 2. Method for manufacturing surface-treated steel The surface-treated steel described above can be manufactured by applying a treatment solution containing a trivalent Cr compound, an organosilicon compound containing one or more amino groups, and a resin to the surface of the plating layer of a plated steel having the steel material and the plating layer, and then drying the applied treatment solution.

[0054] The solvent in the treatment solution is preferably an aqueous medium from the viewpoint of explosion prevention during the manufacturing of surface-treated steel materials. The aqueous medium is a liquid medium mainly composed of water, such as water or a mixture of water and a water-soluble organic solvent. The content of the liquid medium can be appropriately determined within a range of solid content concentrations suitable for application of the treatment solution.

[0055] Examples of trivalent chromium compounds include chromium nitrate, chromium sulfate, chromium phosphate, chromium fluoride, chromium acetate, chromium oxalate, and chromium chloride. These trivalent chromium compounds may be used individually or in combination of two or more.

[0056] The amount of trivalent chromium compound in the treatment solution is preferably 0.30% by mass or more and 20.00% by mass or less, based on the total mass of the solids in the treatment solution (components constituting the film, excluding solvent components), more preferably 0.50% by mass or more and 15.00% by mass or less, more preferably 1.00% by mass or more and 10.00% by mass or less, and even more preferably 1.50% by mass or more and 3.50% by mass or less, based on the amount of trivalent Cr element.

[0057] Examples of organosilicon compounds containing one or more amino groups include 3-aminopropyltrimethoxysilane, n-methyl-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltris(2-methoxyethoxy)silane, n-aminoethyl-3-aminopropyltrimethoxysilane, n-aminoethyl-3-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-ureidopropyltriethoxysilane.

[0058] The treatment solution may also contain other organosilicon compounds. Examples of other organosilicon compounds include methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, vinyltrichlorosilane, vinyltrichlorosilane, vinyltrichlorosilane, and others. These include dimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, vinyltriacetoxysilane, 3-(3,4-epoxycyclohexylethyltrimethoxy)silane, 3-chloropropyltrimethoxysilane, 3-anilidopropyltrimethoxysilane, 3-(4,5-dihydroimidazolepropyltriethoxy)silane, n-phenyl-3-aminopropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, trifluoropropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, and p-styryltrimethoxysilane. These organosilicon compounds may be used individually or in combination of two or more.

[0059] The amount of organosilicon compounds (total of organosilicon compounds having one or more amino groups and other organosilicon compounds) in the treatment solution is preferably 2.00% by mass or more and 30.00% by mass or less, and more preferably 10.00% by mass or more and 20.00% by mass or less, based on the total mass of solids in the treatment solution, in terms of Si element.

[0060] Furthermore, the concentration ratio of trivalent chromium compounds and organosilicon compounds in the treatment solution is preferably 0.050 to 2.600 in terms of the concentration ratio of trivalent Cr to Si element (Cr / Si), more preferably 0.200 to 1.500, and even more preferably 0.500 to 0.650.

[0061] Furthermore, when the treatment solution contains other organosilicon compounds in addition to organosilicon compounds having one or more amino groups, the total amount of these organosilicon compounds is preferably 2.00% by mass or more and 30.00% by mass or less, and more preferably 10.00% by mass or more and 20.00% by mass or less, based on the total mass of solids in the treatment solution, in terms of Si element. In addition, the concentration ratio of these combined organosilicon compounds is preferably 0.050 or more and 2.600 or less, preferably 0.100 or more and 1.500 or less, and more preferably 0.500 or more and 0.650 or less, based on the concentration ratio of trivalent Cr to Si element (Cr / Si).

[0062] The resin can be any of the resins mentioned above. The resin may be an emulsion (water-dispersible resin), or it may be dissolved in water (water-soluble resin). It may also be a prepolymer that hardens upon drying.

[0063] The resin in the processing solution is preferably 0.50% by mass or more and 80.0% by mass or less, more preferably 5.0% by mass or more and 45.0% by mass or less, and even more preferably 30.0% by mass or more and 40.0% by mass or less, based on the total mass of solids in the processing solution.

[0064] When curing the resin during the drying of the treatment solution, the treatment solution may contain a curing agent. As the curing agent, compounds used to cure each of the resins described above can be used.

[0065] The treatment solution may contain a Zr compound.

[0066] Examples of zirconium compounds include zirconium n-propylate, zirconium n-butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium monoethylacetoacetate, zirconium acetylacetonate bisethylacetoacetate, zirconium acetate, zirconium monostearate, zirconate fluoride, zirconium carbonate, ammonium zirconium carbonate, potassium zirconium carbonate, and sodium zirconium carbonate. These Zr compounds may be used individually or in combination of two or more.

[0067] The amount of Zr compound in the treatment solution is preferably 0.10% by mass or more and 20.00% by mass or less, and more preferably 1.0% by mass or more and 10.00% by mass or less, based on the total mass of solids in the treatment solution, in terms of Zr element.

[0068] Furthermore, the concentration ratio of trivalent chromium compounds and Zr compounds in the treatment solution is preferably 0.50 or more and 7.00 or less in terms of the concentration ratio of trivalent Cr to Zr elements (Cr / Zr), and more preferably 1.50 or more and 7.00 or less.

[0069] The treatment solution may contain phosphoric acid or V compounds.

[0070] Examples of phosphoric acids include phosphoric acids such as orthophosphate, metaphosphate, pyrophosphate, triphosphate, and tetraphosphate, or their salts (e.g., ammonium salts such as triammonium phosphate and diammonium hydrogen phosphate), phosphonic acids such as aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra(methylenephosphonic acid), and diethylenetriaminepenta(methylenephosphonic acid), or their salts, as well as organic phosphoric acids such as phytic acid, or their salts. In addition to ammonium salts, metal salts with Na, Mg, Al, K, Ca, Mn, Ni, Zn, and Fe may also be used. These phosphoric acids or their salts may be used individually or in combination of two or more.

[0071] The amount of phosphoric acid in the treatment solution is preferably 0.10% by mass or more and 25.00% by mass or less, and more preferably 1.00% by mass or more and 15.00% by mass or less, based on the total mass of solids in the treatment solution, in terms of element P.

[0072] Examples of V compounds include vanadium compounds obtained by reducing pentavalent vanadium compounds such as vanadium pentoxide, metavanadic acid, ammonium metavanadate, sodium metavanadate, and vanadium oxytrichloride to divalent to tetravalent with a reducing agent, as well as divalent to tetravalent vanadium compounds such as vanadium trioxide, vanadium dioxide, vanadium oxysulfate, vanadium oxyoxalate, vanadium oxyacetylacetonate, vanadium acetylacetonate, vanadium trichloride, phosphovanadomolybdic acid, vanadium sulfate, vanadium dichloride, and vanadium oxide. These vanadium compounds may be used individually or in combination of two or more.

[0073] The amount of V compound in the treatment solution is preferably 0.10% by mass or more and 20.00% by mass or less, and more preferably 1.00% by mass or more and 10.00% by mass or less, based on the total mass of solids in the treatment solution, in terms of element V.

[0074] The treatment solution may contain Co compounds.

[0075] Examples of Co compounds include Co salts such as cobalt nitrate, cobalt sulfate, and cobalt carbonate.

[0076] The amount of Co compound in the treatment solution is preferably 0.01% by mass or more and 10.00% by mass or less, and more preferably 0.10% by mass or more and 5.00% by mass or less, based on the total mass of solids in the treatment solution, in terms of Co element.

[0077] The treatment solution may contain an etching agent. The etching agent activates the surface of the Zn-based plating layer and contributes to improving the adhesion of the chemical conversion treatment film to the Zn-based plating layer. Examples of etching agents include fluorides. The fluoride may be included in the treatment solution as a fluoride of Zr (such as zirconate fluoride) or as another fluoride.

[0078] Furthermore, the treatment solution may contain rheology control agents or other inorganic compounds.

[0079] The treatment solution is preferably applied to the surface of the plating layer by methods such as roll coating, bar coating, and spraying.

[0080] The drying (baking) of the treatment solution applied to the surface of the plating layer is preferably carried out at a temperature higher than 50°C but lower than 250°C, more preferably at a temperature between 70°C and 150°C, and even more preferably at a temperature higher than 100°C but lower than 140°C. Raising the drying temperature above 50°C allows for sufficient volatilization of the solvent. Lowering the drying temperature below 250°C can suppress the decomposition of film components (especially organic chains).

[0081] 3. Applications The above-mentioned surface-treated steel is useful in a variety of applications, such as exterior and interior building materials. For example, the above-mentioned surface-treated steel can be suitably used in a variety of applications, such as roofing materials and exterior materials for buildings, steel pipes, structural steel, supports, and beams for greenhouses or agricultural greenhouses, transport components, sound barriers, soundproof walls, sound-absorbing walls, snow barriers, guardrails, railings, protective fences, supports, components for railway vehicles, components for overhead lines, components for electrical equipment, components for safety and environmental applications, structural components, solar panel mounting frames, and air conditioner outdoor units.

[0082] Furthermore, the above-mentioned surface-treated steel material can be effectively used in applications where surface-treated steel material has traditionally been used, such as sound barriers, windbreaks, and enclosures for power distribution panels.

[0083] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0084] 1. Preparation of materials 1-1. Plated steel sheets Three types of plated steel sheets, A1 to A3 below, were prepared by plating 1.2 mm thick steel sheets with zinc-based plating baths of different compositions. The basis weight of the plating layer was 150 g / m² per side for all of them. ２The following were determined: • A1: Hot-dip Zn-0.5 mass%Al-1 mass%Mg plated steel sheet • A2: Hot-dip Zn-11 mass%Al-3 mass%Mg-0.2 mass%Si plated steel sheet • A3: Hot-dip Zn-19 mass%Al-6 mass%Mg-0.2 mass%Si plated steel sheet

[0085] 1-2. Surface Treatment Solution A surface treatment solution was prepared by mixing the following materials in the ratios shown in Table 1. In this process, a beaker containing materials other than pure water and organosilicon compounds was placed in a bath containing ice, and then the organosilicon compounds were added dropwise while stirring to prepare the treatment solution. The trivalent chromium compound and cobalt compound were in hydrate form, and the amount of each hydrate used is shown in Table 1. Two types of organosilicon compounds were prepared, and one of them was used. Five types of resins were prepared, and one of them was used. • Trivalent chromium compounds: Chromium nitrate notahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) • Organosilicon compounds: (Type B1) 3-aminopropyltriethoxysilane (manufactured by Tokyo Chemical Industries, Ltd.) (Type B2) Ethyltriethoxysilane (manufactured by Tokyo Chemical Industries, Ltd.) • Resins: Polyester resin (Mitsubishi Chemical Corporation) Acrylic resin (Harima Chemicals Group Co., Ltd.) Epoxy resin (ADEKA Corporation) Urethane resin (DIC Corporation) Phenolic resin (Konishi Chemical Industry Co., Ltd.) • Zirconium compounds: Zirconate fluoride (manufactured by Sigma-Aldrich) • Phosphorus compounds: Phosphoric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) • Vanadium compounds: Vanadium pentoxide (manufactured by Tokyo Chemical Industries, Ltd.) • Cobalt compounds: Cobalt nitrate hexahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0086]

[0087] 2. Surface Treatment: A silicate-based alkaline degreasing agent (Fine Cleaner 4336, manufactured by Nippon Parkerizing Co., Ltd.) was sprayed onto the surface of each plated steel sheet at a concentration of 20 g / L and a temperature of 60°C for 2 minutes. After rinsing with pure water for 30 seconds and drying, the surface of each plated steel sheet was degreased.

[0088] Each surface treatment solution was applied to the surface of a degreased plated steel sheet using a bar coater to achieve the desired film thickness. After standing for 3 seconds, the sheet was baked to form a film using the treatment solution. The baking process involved placing the test piece in a 120°C oven for 30 seconds. During baking, the pure water contained in the surface treatment solution, as well as the water in the trivalent chromium compound hydrate and cobalt compound hydrate, evaporates, forming the film.

[0089] 3. Measurement 3-1. A 40 μm × 10 μm test piece was cut from a steel sheet (surface-treated steel sheet) with a thick film formed on it using the cryo-FIB method, in the thickness direction of the steel sheet (perpendicular to the surface of the steel sheet) in a plan view. Next, the cross-section was observed with a transmission electron microscope (TEM) at a magnification (100,000 to 1,000,000 times) in which the entire film and a portion of the plating layer were visible in the field of view. The acceleration voltage during this observation was 200 kV. The film observed at the topmost outside of the plating layer when observed with FE-TEM was identified as the film formed as described above. The boundary between the film and the plating layer can be easily identified from the observation image by a person skilled in the art. In this way, the distance from the boundary between the film and the plating layer to the surface of the film was measured as the film thickness. The film thickness was measured at three points parallel to the steel surface, with measurement intervals changed by 10 μm each, and the average value was taken as the film thickness.

[0090] 3-2. Amount of elements in the coating For all samples, the coating was scraped off with a scrubber in a 3 cm wide and 3 cm long area at a distance of 30 mm or more from the edge of the plated steel sheet. The concentrations of Cr, Si, P, V, Zr, Co, Zn, Al, Mg, and O were calculated from the scraped coating by ICP analysis. The Cr / Si ratio was calculated by converting the ICP results to a mass ratio.

[0091] Furthermore, the Cr content in the coating was investigated using X-ray photoelectron spectroscopy (XPS) on coatings collected from the same area. For the XPS measurements, a mono-Al Kα (hν: 1486.6 eV) X-ray source was used. If the detected peak top position was between 576 and 578 eV, it was determined to be trivalent Cr; if it was between 579 and 580 eV, it was determined to be hexavalent Cr.

[0092] Furthermore, the Si contained in the coating was confirmed to originate from organosilicon compounds using a Fourier transform infrared spectrophotometer (FT-IR). Total internal reflection (ATR) was used at 1100–1000 cm⁻¹. －１ (Siloxane bond), 1500–1300 cm －１ (C-H bond, Si-CH ３ (Bending vibration of the coupling), 900-800 cm (Si-CH ３ Since absorption peaks were detected in all of the bond stretching vibrations, it was determined that the Si originated from an organosilicon compound. The surface-treated steel plate 5 was 1100-1000 cm －１ (Siloxane bond) and 900-800 cm －１ (Si-CH ３ No absorption peaks were detected for the coupling stretching vibrations.

[0093] Furthermore, the types of organosilicon compounds contained in the coating were confirmed using a Fourier transform infrared spectrophotometer (FT-IR). Organosilicon compound B1 was detected by total internal reflection (ATR) at 1650–1580 cm⁻¹. －１ When the absorption peak was detected, it was determined that an amino group derived from organosilicon compound B1 was present in the film. The peak area ratio of the amino group / siloxane bond was 1650–1580 cm². －１ Area of ​​absorption peak / 1100-1000 cm² －１ The absorption peak area was calculated from the area of ​​the absorption peak. Note that surface-treated steel plates 5 and 6 were measured from 1650 to 1580 cm². －１ No peak was detected.

[0094] The Total Internal Reflection (ATR) method was performed under the following measurement conditions: • ATR crystal: Diamond (or Ge) • Measurement mode: ATR single reflection • Measurement wavenumber range: 4000–650 cm －１ ・Resolution: 4cm －１ • Number of cumulative measurements: 32 • Background: Atmospheric background acquired immediately before measurement • Light source: Mid-infrared light source (Glover) • Detector: DTGS • Sample contact: Measurement performed with constant pressure using an ATR head • Measurement position: Any point at least 30 mm away from the edge of the test piece

[0095] Furthermore, the peak area ratio was measured using the obtained spectrum under the following conditions: • Baseline processing: Linear baseline method • Area calculation method: Wavenumber integral (1650–1580 cm²) －１ / 1100-1000cm －１ )

[0096] Table 2 shows the type of plated steel sheet, the type of treatment solution, the amount of each element, the concentration of trivalent Cr and Si in the film, the mass ratio of Cr / Si, and the film thickness for surface-treated steel sheets coated with each treatment solution. Note that the concentration of trivalent Cr and Si in the film is the concentration in the film formed with anhydrous materials.

[0097]

[0098] 4. Evaluation 4-1. Planar Corrosion Resistance The corrosion resistance of the planar surfaces of the surface-treated steel sheets was evaluated. More specifically, test pieces (70 mm wide x 150 mm long) cut from each surface-treated steel sheet were sealed at the end face, and then subjected to a salt spray process, a drying process, and a wetting process for one cycle (totaling 8 hours). This cycle was repeated until the area rate of white rust occurrence reached 10%.

[0099] In the salt spray process, a 5% NaCl aqueous solution at 35°C was sprayed onto the test specimens for 2 hours. In the drying process, the test specimens were left for 4 hours in an environment with a temperature of 60°C and a relative humidity of 30%. In the wetting process, the test specimens were left for 2 hours in an environment with a temperature of 50°C and a relative humidity of 95%. The test specimens were evaluated according to the following criteria based on the number of cycles until the area rate of white rust reached 10%. Scores from SS to A were considered acceptable.

[0100] <Evaluation Criteria> Score SS: Over 330 cycles S: Over 280 cycles and 330 cycles or less A: Over 160 cycles and 280 cycles or less B+: Over 120 cycles and 160 cycles or less B: 120 cycles or less

[0101] 4-2. Corrosion Resistance of Processed Areas The corrosion resistance of the processed areas of the surface-treated steel sheets was evaluated. More specifically, test pieces (50 mm wide x 50 mm long) cut from each surface-treated steel sheet were extruded to a thickness of 7 mm using an Erichsen extrusion apparatus. The same test as the evaluation of planar corrosion resistance described above was performed on the obtained extruded samples, and the test pieces were evaluated according to the following criteria based on the number of cycles until the area rate of white rust reached 10%. Scores of S and A were considered acceptable.

[0102] <Evaluation Criteria> Score: More than 21 cycles A: More than 15 cycles and 21 cycles or less B+: More than 10 cycles and 15 cycles or less B: 10 cycles or less

[0103] 4-3. Heat Resistance Test The heat resistance of the surface-treated steel sheets obtained was evaluated. More specifically, after sealing the end faces of test pieces (70 mm wide x 150 mm long) cut from each surface-treated steel sheet, they were heated in an oven at 200°C for 2 hours, and then a salt spray test according to JIS Z 2371 for corrosion resistance of the flat surface was performed for 48 hours, and the occurrence of white rust was observed. A score of S and a score of A were considered acceptable.

[0104] <Evaluation Criteria> Score S: Rust occurrence is less than 10% of the total area A: Rust occurrence is 10% or more but less than 40% of the total area B: Rust occurrence is 40% or more of the total area

[0105] 4-4. Fingerprint Resistance The fingerprint resistance of the surface-treated steel sheets was evaluated. More specifically, the increase or decrease in L value (ΔL) before and after the application of petroleum jelly was measured using a colorimeter on test pieces (50 mm wide x 50 mm long) cut from each surface-treated steel sheet. Both S and A scores were considered acceptable.

[0106] <Evaluation Criteria> Score S: ΔL is less than 0.5 A: ΔL is 0.5 or more and less than 1.0

[0107] 4-5. Sliding Properties The sliding properties of the surface-treated steel sheets were evaluated. More specifically, test pieces (17 mm wide x 300 mm long) cut from each surface-treated steel sheet were subjected to a drawbead testing machine with a pressing load of 2.0 to 5.5 kN and slid for 200 mm at a pull-out speed of 500 mm / min. The load when sliding at each pressing load was measured as the pull-out load, and the slope of the line plotted with the pressing load on the x-axis and the pull-out load on the y-axis was calculated as the sliding coefficient. The sliding properties were evaluated according to the following sliding coefficient criteria. A score of A was considered a passing grade.

[0108] <Evaluation Criteria> Score S: Sliding coefficient less than 0.5 A: Sliding coefficient of 0.5 or more and less than 0.7 B: Sliding coefficient of 0.7 or more

[0109] 4-6. The blackening resistance of the surface-treated steel sheets obtained was evaluated. More specifically, test pieces (50 mm wide x 50 mm long) cut from each surface-treated steel sheet were placed in a constant temperature chamber at 70°C and 80% humidity for 144 hours, and the lightness (L* value) of the test pieces was measured before and after the test. Lightness was measured using a colorimeter (Konica Minolta, Inc., CR-400) with a diffuse illumination vertical receiving method including specular reflection light in accordance with JIS Z8722:2009. The illumination diameter during measurement was 11 mmφ, and the measurement diameter was 8 mmφ. Based on the change in lightness (ΔL* value) before and after the test, the blackening resistance was evaluated according to the following criteria. Both a score of S and a score of A were considered acceptable.

[0110] <Evaluation Criteria> Score S: ΔL* value is 0 or greater and less than 10 A: ΔL* value is 10 or greater and less than 15

[0111] The evaluation results for each surface-treated steel sheet are shown in Table 3.

[0112]

[0113] As shown in Tables 1 to 3, the coating has a film containing trivalent Cr, an organosilicon compound, and a resin, the concentration of trivalent Cr in the coating is 0.30% by mass or more and 20.0% by mass or less, and the coating is measured using a Fourier transform infrared spectrophotometer (FT-IR) and has a temperature of 3500 to 3300 cm⁻¹. －１ and 1650-1580 cm －１Surface-treated steel materials in which peaks indicating amino groups were detected in both directions exhibited high corrosion resistance and a low coefficient of friction.

[0114] Furthermore, in the surface-treated steel sheet 4, which does not contain trivalent Cr or Zr, the area rate of white rust reached 10% after 115 cycles in the planar corrosion resistance test, and after 7 cycles in the processed surface corrosion resistance test. In contrast, in the surface-treated steel sheet 22, which does not contain trivalent Cr but contains Zr, the area rate of white rust reached 10% after 139 cycles in the planar corrosion resistance test, and after 11 cycles in the processed surface corrosion resistance test. Thus, Zr alone can improve the corrosion resistance of surface-treated steel sheets.

[0115] Furthermore, in the surface-treated steel sheet 1 containing trivalent Cr but not Zr, the area rate of white rust reached 10% after 197 cycles in the planar corrosion resistance test, and after 16 cycles in the processed surface corrosion resistance test. In contrast, in the surface-treated steel sheet 8 containing both trivalent Cr and Zr, the area rate of white rust reached 10% after 302 cycles in the planar corrosion resistance test, and after 25 cycles in the processed surface corrosion resistance test.

[0116] These results show that the degree of improvement in corrosion resistance due to Zr when trivalent Cr is included (comparison between surface-treated steel sheet 2 and surface-treated steel sheet 8) is significantly higher than the degree of improvement due to Zr when trivalent Cr is not included (comparison between surface-treated steel sheet 4 and surface-treated steel sheet 22).

[0117] On the other hand, surface-treated steel sheet 2, with a trivalent Cr concentration of less than 0.30 mass%, exhibited lower corrosion resistance on its flat surface and processed areas compared to other surface-treated steel sheets. This is thought to be because a dense film structure due to trivalent Cr was not formed, resulting in insufficient barrier properties. Furthermore, surface-treated steel sheet 3, with a trivalent Cr concentration exceeding 20.00 mass%, had a higher coefficient of friction than other surface-treated steel sheets. This is thought to be due to the aggregation and uneven distribution of trivalent Cr.

[0118] This application claims priority to Japanese Patent Application No. 2025-057066, filed on 28 March 2025. The matters set forth in the original specifications and claims of these applications are incorporated herein by reference.

[0119] The surface-treated steel materials described above possess high corrosion resistance and high heat resistance. Therefore, they are useful in various applications where these properties are required.

Claims

1. A surface-treated steel material comprising a steel material, a Zn-containing plating layer, and a coating, arranged in this order, wherein the coating contains trivalent Cr, an organosilicon compound, and a resin, the concentration of trivalent Cr in the coating is 0.30% by mass or more and 20.00% by mass or less, and the coating has a density of 3500 to 3300 cm² as measured using a Fourier transform infrared spectrophotometer (FT-IR). －１ and 1650-1580 cm －１ Surface-treated steel material in which peaks indicating amino groups are detected in both.

2. The surface-treated steel material according to claim 1, wherein the peak indicating the amino group is a peak derived from the organosilicon compound.

3. The surface-treated steel material according to claim 1, wherein the coating contains Zr.

4. The surface-treated steel material according to claim 1, wherein the mass concentration ratio (Cr / Si) of the trivalent Cr to the Si derived from the organosilicon compound in the coating is 0.050 or more and 2.600 or less.

5. The surface-treated steel material according to claim 1, wherein the coating comprises P or V.

6. The surface-treated steel material according to claim 1, wherein the coating contains Co.

7. The surface-treated steel material according to claim 1, wherein the resin is at least one resin selected from the group consisting of acrylic resin, epoxy resin, urethane resin, polyester resin, and phenolic resin.

8. The surface-treated steel material according to claim 1, wherein the coating has a thickness of 0.250 μm or more and 10.00 μm or less.

9. The surface-treated steel material according to any one of claims 1 to 8, wherein the plating layer has an Al content of 1.0% by mass or more and 22.0% by mass or less, an Mg content of 1.5% by mass or more and 10.0% by mass or less, and the remainder consists of Zn and optionally added trace additives.

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