CHAPA METÁLICA COM SUPERFÍCIE TRATADA E MEMBRO AUTOMOTIVO.

Abstract

This surface-treated metal sheet comprises a metal sheet and a coating film formed on a surface of the metal sheet and having a thickness of 0.5-5.0 μm. The coating film comprises a binder resin, doped oxide particles, and a rust-preventive pigment. The content of the doped oxide particles is 5-20 vol% with respect to the coating film. The content of the rust-preventive pigment is 20-50 vol% with respect to the coating film. The ratio of the average particle diameter (B) of the doped oxide particles to the average particle diameter (A) of the rust-preventive pigment, B / A, is 0.75-4.00.

Description

1 / 55 Metal sheet with treated surface and automotive component. Technical Field

[0001] The present invention relates to a metal sheet with a treated surface and an automotive component. Background

[0002] A large number of automotive members are made of sheet metal such as steel sheet as a material and are manufactured through a large number of steps such as (1) a step of cutting the sheet metal to a predetermined size, (2) a step of washing the cut sheet metal, (3) a step of press-molding the washed sheet metal, (4) a step of joining the molded material by spot welding, adhesion or similar, (5) a step of degreasing and washing away the pressing oil from the surface of the joined member, (6) a step of chemical conversion treatment and (7) a step of coating. In addition, an automotive member used as an outer sheet is usually subjected to additional coating steps such as (8) an intermediate coating step (9) a top coating step.Therefore, in the automotive industry, there is a great demand for cost reduction through the simplification of manufacturing steps, particularly chemical conversion and coating treatment steps.

[0003] In addition, satisfactory corrosion resistance of an automotive member is often obtained by a chemical conversion treatment of a layer formed by means of a chemical conversion treatment step and an electrodeposited film formed by means of a subsequent electrodeposition coating step. However, joints of a molded material (particularly inner plate and inner plate joints) Petition 870250085418, dated 09 / 22 / 2025, page 11 / 78 2 / 55 folded sheaths of the bag-shaped members) are more likely to be exposed to a corrosive environment in an uncovered state, without being surrounded by an electrodeposited film. Therefore, an auxiliary rust prevention material, such as a sealant or anti-rust wax, is used to increase the corrosion resistance of the molded material joints. The use of these auxiliary rust prevention materials not only increases the manufacturing cost of an automobile but also reduces productivity and increases the weight of the automobile body. Thus, there is a high demand for an automotive member capable of achieving satisfactory corrosion resistance even when the use of these auxiliary rust prevention materials is reduced.

[0004] In response to this demand, research and development of a metal sheet with a surface treatment capable of simultaneously simplifying the chemical conversion treatment and electrodeposition coating steps during automobile manufacturing and reducing the need for rust prevention auxiliary materials has been actively conducted. Such a metal sheet with a surface treatment is assembled into a desired shape, for example, spot welding after pressure molding, followed by the application of an electrodeposition coating. Therefore, it is necessary to impart conductivity to a coating film so that resistance welding and / or electrodeposition coating can be performed on the metal sheet with the surface treatment, thus providing corrosion resistance to the coating film.

[0005] For example, PTL 1 describes a metal sheet with a surface treatment in which a coating film containing a binder resin, oxide particles, non-oxide ceramic particles, and a rust-inhibiting pigment is formed on the surface of a metal sheet, such as a metal sheet with a surface treatment that meets the demand described above. The oxide particles are dissolved during Petition 870250085418, dated 09 / 22 / 2025, page 12 / 78 3 / 55 A chemical conversion treatment step is used to impart an anchoring effect to a chemical conversion treatment layer and, as a result, increase the adhesion of an electrodeposited film subsequently formed to the surface-treated sheet metal. Non-oxide ceramic particles act as conductive particles to impart conductivity to the coating film. The rust-inhibiting pigment imparts corrosion resistance to the surface-treated sheet metal. As a result, the surface-treated sheet metal described in PTL 1 exhibits excellent adhesion to an electrodeposited film, weldability, and corrosion resistance. List of Citations

[0006] Patent Literature PTL 1 International Publication No. WO 2016 / 159138 Summary of the Invention Technical Problem

[0007] However, there is room for improvement in the sheet metal with surface treatment described in PTL 1 from the point of view of manufacturing cost. That is, in the sheet metal with surface treatment described in PTL 1, expensive non-oxide ceramic particles are used as conductive particles. In this way, the manufacturing cost of the sheet metal with surface treatment increases significantly and the expected cost advantage from the reduction of rust prevention auxiliary materials is compromised.

[0008] One objective of the present invention is to provide a metal sheet with a surface treatment on which resistance welding and electroporation coating can be performed, and the metal sheet with the surface treatment exhibits excellent corrosion resistance and can be manufactured without the use of particles. Petition 870250085418, dated 09 / 22 / 2025, page 13 / 78 4 / 55 non-oxide ceramics. That is, an objective of the present invention is to provide a metal sheet with a surface treatment that does not contain non-oxide ceramic particles. In addition, another objective of the present invention is to provide an automotive member including the metal sheet with a surface treatment, that is, an automotive member including a metal sheet with a surface treatment that exhibits excellent corrosion resistance and does not include non-oxide ceramic particles; in addition, resistance welding and electrodeposition coating can be performed on the metal sheet with the surface treatment. Solution to the Problem

[0009] The present invention relates to the following metal sheet with surface treatment and automotive component.

[0010] Namely: [1] A metal sheet with surface treatment, including: a metal sheet; and a coating film disposed on a surface of the metal sheet and having a thickness of 0.5 to 5.0 μm, in which the coating film includes a binder resin, a doped oxide particle and a rust inhibitor pigment, the content of the doped oxide particle being 5% to 20% by volume with respect to the coating film, the content of the rust inhibitor pigment being 20% ​​to 50% by volume with respect to the coating film and a value (B / A) of a ratio of an average particle diameter (B) of the doped oxide particle to an average particle diameter (A) of the rust inhibitor pigment being 0.75 to 4.00. [2] Metal sheet with surface treatment according to [1], in which the average particle diameter of the doped oxide particle is from 1.0 to 4.0 μm. [3] Metal sheet with surface treatment according to [1] or [2], in which the doped oxide particle includes at least one selected member of the group Petition 870250085418, dated 09 / 22 / 2025, page 14 / 78 5 / 55 consisting of a zinc oxide particle doped with Al, Ga or In; a tin oxide particle doped with P, Sb or As; an indium oxide particle doped with Sn or Ge; a titanium oxide particle coated with zinc oxide doped with Al, Ga or In; a titanium oxide particle coated with tin oxide doped with P, Sb or As; and a titanium oxide particle coated with indium oxide doped with Sn or Ge. [4] Metal sheet with surface treatment according to any of [1] to [3], in which the average particle diameter of the rust inhibitor pigment is 0.5 to 4.0 μm. [5] Metal sheet with surface treatment according to any one of [1] to [4], in which the rust inhibitor pigment includes at least one member selected from the group consisting of a phosphate compound, a silicate compound, amorphous silica and a vanadate compound. [6] Metal sheet with surface treatment according to any one of [1] to [5], wherein the binder resin is a water-soluble or water-dispersible aqueous resin. [7] Metal sheet with surface treatment according to [6], wherein the binder resin is an epoxy resin. [8] Metal sheet with surface treatment according to any one of [1] to [7], in which the coating film does not include any non-oxide ceramic particle, an iron alloy particle and a stainless steel particle. [9] an automotive member comprising a coated sheet metal, wherein the coated sheet metal includes sheet metal with surface treatment according to any one of [1] to [8], a chemical conversion treatment layer disposed on a surface of the coating film and an electrodeposited film on a surface of the chemical conversion treatment layer. Advantageous Effects of the Invention Petition 870250085418, dated 09 / 22 / 2025, page 15 / 78 6 / 55

[0011] The present invention can provide a metal sheet with a surface treatment in which resistance welding and electrodeposition coating can be performed, and the metal sheet with the surface treatment exhibits excellent corrosion resistance and can be manufactured more economically than conventional methods. The present invention can also provide an automotive member comprising the metal sheet with the surface treatment.

[0012] Brief Description of the Drawings FIG. 1 is a schematic view illustrating a cross-section of a metal sheet with surface treatment according to an embodiment of the present invention; FIG. 2A is a schematic view illustrating a cross-section of a coating film with the value of the ratio between the average particle diameters being within a predetermined range, and FIG. 2B is a schematic view illustrating a cross-section of a coating film with the value of the ratio between the average particle diameters being outside the predetermined range; FIG. 3A is a backscattered electron image (composition image) of the cross-section of the metal sheet coating film with surface treatment according to the embodiment of the present invention, and FIGS. 3B to 3G are element mapping images of multiple elements in the same field of view; FIG. 4A is a backscattered electron image (composite image) of a cross-section of a coating film on a metal sheet with surface treatment for comparison, and FIGS. 4B to 4G are element mapping images of multiple elements in the same field of view; and FIG. 5 is a schematic view illustrating a cross-section of a coated metal sheet according to the embodiment of the present invention. Description of Achievements Petition 870250085418, dated 09 / 22 / 2025, page 16 / 78 7 / 55

[0013] Hereafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this.

[0014] In this report, a numerical range represented by the term “a” includes the values ​​before and after the term “a” as the respective lower and upper limits of the numerical range. In the numerical ranges described step-by-step here, the upper or lower limit value described in a certain numerical range can be replaced with the upper or lower limit value of another numerical range in the ranges described step-by-step. Metal sheet with surface treatment

[0015] The metal sheet with surface treatment according to an embodiment of the present invention includes a metal sheet and a coating film disposed on the surface of the metal sheet. The coating film is disposed on at least one major surface of the metal sheet and includes a binder resin, doped oxide particle and a rust inhibitor pigment.

[0016] FIG. 1 is a schematic view illustrating a cross-section of the metal sheet with surface treatment according to the embodiment of the present invention. In the example illustrated in FIG. 1, the metal sheet with surface treatment (100) includes the metal sheet (110) and the coating film (120) disposed on a surface of the metal sheet (110). The coating film (120) includes the binder resin (122), doped oxide particle (124) and rust inhibitor pigment (126).

[0017] Hereafter, each constituent element of the sheet metal with surface treatment will be described. Metal sheet

[0018] The type of sheet metal is not particularly limited and can be selected appropriately depending on the applications. Examples of sheet metal materials include steel (an iron-based alloy), aluminum, an aluminum alloy, magnesium, and a magnesium alloy. Petition 870250085418, dated 09 / 22 / 2025, page 17 / 78 8 / 55

[0019] Steel sheet can be ordinary steel sheet or special steel sheet containing an added element such as chromium. However, when pressure forming is performed, it is preferable that the steel sheet be a steel sheet in which the type and quantity of the added element, as well as the metallic microstructure, are appropriately controlled so that the steel sheet exhibits the desired formability. The steel sheet can be galvanized steel sheet. Examples of galvanized steel sheet include zinc-based galvanized steel sheet and aluminum-based galvanized steel sheet.

[0020] Examples of a zinc-based galvanizing layer of zinc-based galvanized steel sheet include a zinc-composite galvanizing layer; a zinc alloy galvanizing layer and at least one selected member of the group consisting of aluminum, cobalt, tin, nickel, iron, chromium, titanium, magnesium, and manganese; and various zinc alloy galvanizing layers additionally containing other metallic or non-metallic elements (e.g., a four-component alloy galvanizing layer of zinc, aluminum, magnesium, and silicon). However, in the zinc-based galvanizing layer, the alloy components other than zinc are not particularly limited.These zinc-based galvanizing layers may additionally contain cobalt, molybdenum, tungsten, nickel, titanium, chromium, aluminum, manganese, iron, magnesium, lead, bismuth, antimony, tin, copper, cadmium, arsenic or similar substances, as a small amount of foreign metallic element or impurities may contain an inorganic substance such as silica, alumina or titania.

[0021] Examples of an aluminum-based galvanizing layer of aluminum-based galvanized steel sheet include an aluminum composite galvanizing layer; and an aluminum alloy galvanizing layer and at least one selected member of the group consisting of silicon, zinc and magnesium (for example, a layer Petition 870250085418, dated 09 / 22 / 2025, page 18 / 78 9 / 55 aluminum-silica alloy galvanizing, one layer of aluminum-zinc alloy galvanizing, and one layer of three-component aluminum, silicon, and magnesium alloy galvanizing.

[0022] Zinc-based galvanized steel sheet and aluminum-based galvanized steel sheet may be a multi-layered galvanized steel sheet combined with another type of galvanizing layer (for example, an iron galvanizing layer, an iron-phosphorus alloy galvanizing layer, a nickel galvanizing layer, a cobalt galvanizing layer, and the like).

[0023] A method for forming a galvanizing layer is not particularly limited. For example, electroplating, non-electrical galvanizing, hot-dip galvanizing, steam deposition galvanizing, dispersion galvanizing, or similar methods can be used for forming a galvanizing layer. The galvanizing layer can be formed either by a continuous method or by a batch method. In addition, after the formation of a galvanizing layer, a "zero spangle" treatment to make the appearance uniform, annealing treatment to modify the galvanizing layer, and cold rolling to adjust the surface condition or material properties, or similar, can be performed. Coating Film

[0024] The coating film is applied to at least one major surface of the sheet metal described above (i.e., to at least one surface). The term “major surface” refers to each of two relatively large surfaces (the front surface and the back surface) between the sheet metal surfaces. Depending on the applications, the coating film may be formed on both surfaces (both major surfaces) of the sheet metal or it may be formed only on one surface (one major surface) of the sheet metal. In addition, the Petition 870250085418, dated 09 / 22 / 2025, page 19 / 78 10 / 55 coating film can be formed on only part of the metal sheet surface or it can be formed over the entire surface of the metal sheet.

[0025] The coating film includes a binder resin, doped oxide particles, and a rust-inhibiting pigment. The coating film may contain other additives or similar as required. Binder Resin

[0026] The binder resin functions as a bonding agent that links the components in the coating film together. The binder resin can be a water-soluble or water-dispersible aqueous resin that is dissolved in water, or it can be a solvent-based resin that is dissolved or dispersed in an organic solvent. From a cost and environmental suitability standpoint, the binder resin is preferably an aqueous resin.

[0027] The type of aqueous resin is not particularly limited. Aqueous resin is, for example, a water-soluble or water-dispersible resin such as an epoxy resin, a urethane resin, a polyester resin, an acrylic resin, a phenolic resin, and a mixed resin of two or more types of these resins.

[0028] When an epoxy resin is used as an aqueous resin, the number average molecular weight (Mn) of the epoxy resin is not particularly limited, however, it is preferably from 1400 to 20000, more preferably from 2000 to 10000 and particularly preferably from 2000 to 4000. That is, the lower limit of the number average molecular weight (Mn) of the epoxy resin is preferably 1400 or more and more preferably 2000 or more. The upper limit of the number average molecular weight (Mn) of the epoxy resin is preferably 20000 or less, more preferably 10000 or less and particularly preferably 4000 or less. When the number-average molecular weight of the epoxy resin is between 1400 and 20000, a crosslinking reaction proceeds sufficiently during the crosslinking of the epoxy resin, thus increasing the corrosion resistance of the metal sheet with surface treatment. In addition, it is Petition 870250085418, dated 09 / 22 / 2025, p. 20 / 78 11 / 55 It is possible to suppress an excessive increase in the crosslinking density of the coating film, thereby maintaining the processability of the coating film. When simply described as an epoxy resin in this report, this means that at least one selected member of the group consisting of an epoxy resin and a modified epoxy resin product is included. In addition, in this report, the number average molecular weight (Mn) of a resin means a number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0029] The glass transition temperature (Tg) of epoxy resin is not particularly limited, however it is, for example, 120°C or lower and can be 115°C or lower or 110°C or lower. The glass transition temperature (Tg) of epoxy resin is, for example, 50°C or higher or can be 55°C or higher. For example, the glass transition temperature (Tg) of epoxy resin can be from 50°C to 120°C. When the glass transition temperature (Tg) of epoxy resin is from 50°C to 120°C, the moisture permeability of the coating film does not become excessively high, thus increasing the corrosion resistance of the metal sheet with surface treatment. The glass transition temperature (Tg) can be measured using, for example, a TMA7100 thermal analysis instrument (Hitachi HighTech Science Corporation).

[0030] The acid value of epoxy resin (including a modified product thereof) is not particularly limited, however, for example, from 0 to 30 mgKOH / g. In this report, the acid value means an acid value of the solid content and can be measured in accordance with the provisions of JIS K 0070.

[0031] The epoxy resin is preferably in an emulsion form having an emulsion particle diameter of 10 to 100 nm (preferably 20 to 60 nm). When the emulsion particle diameter is excessively small, the cost of Petition 870250085418, dated 09 / 22 / 2025, page 21 / 78 12 / 55 manufacturing can increase. On the other hand, when the particle diameter of the emulsion is excessively large, the space between the emulsion particles can be increased when a coating film is formed from the epoxy resin, thus reducing the barrier properties of the coating film.

[0032] The type of epoxy resin is not particularly limited. Epoxy resin may be a hydroxyl-containing epoxy resin (including modified hydroxyl-containing epoxy resin products). Examples of epoxy resin include a resin obtained by condensation of epichlorohydrin and bisphenol to a high molecular weight component in the presence of a catalyst such as an alkaline catalyst, as required; a bisphenol-type epoxy resin such as a bisphenol A-type epoxy resin and a bisphenol F-type epoxy resin; and a novolac-type epoxy resin. Examples of modified epoxy resin products include modified epoxy resins such as an acrylic-modified epoxy resin, a urethane-modified epoxy resin, and an amine-modified epoxy resin.For example, acrylic-modified epoxy resin can be prepared by reacting bisphenol-type epoxy resin or novolac-type epoxy resin with a polymerizable unsaturated monomeric component containing acrylic acid or similar. In addition, urethane-modified epoxy resin can be prepared by reacting bisphenol-type epoxy resin or novolac-type epoxy resin with a polyisocyanate compound. These epoxy resins can be used separately or in combination.

[0033] When a polyester resin is used as the aqueous resin, the number average molecular weight (Mn) of the polyester resin is not particularly limited, however it is preferably from 10000 to 30000. When the number average molecular weight of the polyester resin is less than 10000, it may be difficult to obtain sufficient processability. On the other hand, when the number average molecular weight of the polyester resin exceeds 30000, the adhesion between the coating film and a film Petition 870250085418, dated 09 / 22 / 2025, page 22 / 78 13 / 55 electrodeposited formed on the coating film may be reduced. In addition, when crosslinking is performed using a curing agent such as melamine, the crosslinking reaction may be insufficient and the performance of the coating film may be reduced.

[0034] When a urethane resin is used as the aqueous resin, the urethane resin is preferably in an emulsion form having an emulsion particle diameter of 10 to 100 nm (preferably 20 to 60 nm). When the emulsion particle diameter is excessively small, the cost may increase. On the other hand, when the emulsion particle diameter is excessively large, a space between the emulsion particles may be increased when a coating film is formed from the urethane resin, thus reducing the barrier properties of the coating film. The type of urethane resin is not particularly limited. Examples of urethane resin include a polyether-based urethane resin, a polycarbonate-based urethane resin, and a polyester-based urethane resin. These can be used separately or in combination.

[0035] Examples of solvent-based resins include epoxy resin, polyester resin, urethane resin, acrylic resin, and a mixed resin of two or more types of these resins.

[0036] The binder resin can be a crosslinked resin exhibiting a crosslinking structure or a non-crosslinked resin not exhibiting a crosslinking structure. From the point of view of forming a coating film at low temperature, the binder resin is preferably a non-crosslinked resin.

[0037] As a crosslinking agent (curing agent) that imparts a crosslinking structure to the binder resin, a water-soluble crosslinking agent is preferred. Specifically, the crosslinking agent is preferably melamine, isocyanate, or the like. The amount of crosslinking agent to be added is not Petition 870250085418, dated 09 / 22 / 2025, page 23 / 78 14 / 55 particularly limited, however, it is preferably 5 parts by mass to 30 parts by mass relative to 100 parts by mass of the resin solids content. When the amount of crosslinking agent added is less than 5 parts by mass, the crosslinking reaction with the resin may proceed insufficiently and the performance of the coating film may become insufficient. On the other hand, when the amount of crosslinking agent added is greater than 30 parts by mass, the crosslinking reaction may proceed excessively, making the coating film excessively hard, thus reducing processability.

[0038] The binder resin content is not particularly limited, however it is preferably from 20% to 80% by mass relative to the coating film (total solids content of the coating film). When the binder resin content is less than 20% by mass, a function as a binder may not be exhibited, a form of aggregation of the coating film may be reduced, and the adhesion of the coating film may be reduced or the destruction of the coating film aggregation may be more likely to occur. When the binder resin content exceeds 80% by mass, the proportion of the pigment component (e.g., doped oxide particle and rust inhibitor pigment) contained in the coating film is reduced, and it may be difficult to obtain full conductivity, corrosion resistance, and adhesion.From the point of view of exhibiting a binder function and obtaining conductivity, corrosion resistance, and adhesion, the binder resin content is more preferably from 25% to 70% by mass and even more preferably from 30% to 60% by mass relative to the coating film (total solids content of the coating film). That is, the lower limit of the binder resin content is 20% by mass or more, preferably 25% by mass or more and even more preferably 30% by mass or more relative to the coating film (total solids content of the coating film). The upper limit of the binder resin content is 80% by mass or less, preferably less. Petition 870250085418, dated 09 / 22 / 2025, page 24 / 78 15 / 55 70% by mass or less, and more preferably 60% by mass or less in relation to the coating film (total solids content of the coating film).

[0039] The binder resin content is calculated by the following mass spectrometry. A sample is obtained by scraping the coating film from the metal sheet with surface treatment, and the obtained sample is subjected to analysis based on gas chromatography thermal decomposition mass spectrometry (GC-MS). Specifically, a predetermined amount of polystyrene as a standard substance is added to the obtained sample, and the sample is heated to 600°C and thermally decomposed by a GC-MS instrument (e.g., a GC “7890B” system manufactured by Agilent Technologies, Inc.). The decomposition products obtained by thermal decomposition are analyzed by GC-MS and subjected to peak analysis to identify the type and quantity of decomposition products.From the analyzed peaks, the peak area of ​​the styrene monomers corresponding to the known mass (predetermined quantity) of polystyrene added as a standard substance is compared with the peak areas of all remaining peaks corresponding to the binder resin, thus determining the quantity of binder resin. By calculating a ratio of the quantity of binder resin to the mass of the scraped sample (coating film), the content (% by mass) of binder resin in the coating film is obtained.

[0040] When the binder resin includes an epoxy resin, a urethane resin and / or a polyester resin, from the point of view of adhesion to a metal sheet and retention of the pigment component, a proportion of the sum of the quantities of epoxy resin, urethane resin and polyester resin to the whole binder resin is preferably 50% or more, more preferably more than 50% and particularly preferably 60% by volume or more. The binder resin may be composed of a combination of an epoxy resin, a urethane resin and a polyester resin. That is, the sum of the contents of epoxy resin, urethane resin and polyester resin in the binder resin Petition 870250085418, dated 09 / 22 / 2025, p. 25 / 78 16 / 55 could be 100%. Doped Oxide Particle

[0041] Doped oxide particles are particles in which at least one surface is composed of a metallic oxide containing a dopant element (impurity). The doped oxide particle exhibits conductivity and imparts conductivity to the coating film. Since the steel sheet with a surface treated according to the present embodiment includes the doped oxide particle in its coating film, resistance welding and electrodeposition coating can be performed even when other conductive particles such as non-oxide ceramic particles, iron alloy particles, and stainless steel particles are not contained in the coating film.

[0042] In addition, when the steel sheet with a surface treated according to the present embodiment is subjected to coating such as electrodeposition coating, a chemical conversion treatment is often carried out prior to the coating in order to form a chemical conversion treatment layer. Representative examples of such a chemical conversion treatment layer include an acid salt film such as a phosphate film. A chemical conversion treatment liquid for the formation of such an acid salt layer is acidic (e.g., pH 2 to 3) and the doped oxide particle exhibits properties such that the doped oxide particle dissolves in an acidic chemical conversion treatment liquid.Thus, when the steel sheet with a surface treated according to the present embodiment is subjected to a chemical conversion treatment using an acidic chemical conversion treatment liquid, the doped oxide particle in the surface layer of the coating film is dissolved and the pH in the vicinity increases; in this way, a component of the chemical conversion treatment liquid (for example, an acidic salt such as a phosphate) is precipitated and grown in a location where the doped oxide particle is. Petition 870250085418, dated 09 / 22 / 2025, page 26 / 78 17 / 55 dissolved. As a result, the chemical conversion treatment liquid component is considered to grow in a wedge shape to project from the interior of the coating film surface layer to the surface. When a deposited film is formed by electrodeposition or similar coating on the chemical conversion treatment layer from which crystals of the chemical conversion treatment liquid components project, the adhesion between the coating film and the deposited film is further increased by an anchoring effect of the wedge-shaped grown crystals (e.g., crystals of an acid salt such as a phosphate), in addition to the high adhesion due to the chemical properties of the chemical conversion treatment liquid components (see FIG. 5).

[0043] In addition, as described above, the coating film also includes a rust-inhibiting pigment. The rust-inhibiting pigment is dissolved by an acidic chemical conversion treatment liquid depending on its type. However, when doped oxide particles are incorporated into the coating film along with the rust-inhibiting pigment, the doped oxide particles are actively dissolved by an acidic chemical conversion treatment liquid, such that the rust-inhibiting pigment is less likely to be dissolved. In this way, the corrosion resistance of the steel sheet with a surface treated according to the present embodiment is further increased.

[0044] A metal oxide that constitutes the doped oxide particle (a metal oxide doped with a dopant element) is not particularly limited in that it can impart conductivity to the coating film and examples of these include zinc oxide (ZnO), tin oxide (SnÜ2) and indium oxide (In2Ü3).

[0045] The doped oxide particle may have a configuration such that all particles are composed of a metal oxide containing a dopant element or only the surface layer of the particles is composed of a metal oxide containing a dopant element. Petition 870250085418, dated 09 / 22 / 2025, p. 27 / 78 18 / 55 dopant element. For example, the doped oxide particle may be a zinc oxide particle doped with a dopant element, a tin oxide particle doped with a dopant element, or an indium oxide particle doped with a dopant element. In addition, doped oxide particles may be particles in which particles composed of another metal oxide are coated with zinc oxide, tin oxide, or indium oxide, each doped with a dopant element. Examples of other metal oxides include titanium oxide (TiO2).

[0046] As the dopant element, an element having a different number of valence electrons from a metallic element contained in the metallic oxide (e.g., Zn, Sn, or In) is used. For example, as the dopant element of zinc oxide (ZnO, valence 2), at least one element selected from the group consisting of Group 13 elements (valence 3) of the periodic table and Group 15 elements (valence 5) of the periodic table is preferably selected. Among these, Al, Ga, and In, which are Group 13 elements having a valence closer to that of the metallic element, are most preferred, and Al and Ga are particularly preferred. In addition, as the dopant element of tin oxide (SnO2, valence 4), at least one element selected from the group consisting of Group 15 elements (valence 5) of the periodic table is preferably selected. Among these, P, Sb, and As are most preferred, and P and Sb are particularly preferred.In addition, as the dopant element of indium oxide (IirO3, valence 3), at least one element selected from the group consisting of the Group 14 elements (valence 4) of the periodic table is preferably selected. Among these, Sn and Ge are most preferred, and Sn is particularly preferred. As described above, by combining the metal oxide with the dopant element, the metal oxide conducts electricity as an n-type semiconductor.

[0047] For example, doped oxide particles include at least one selected member of the group consisting of zinc oxide particles doped with Al, Ga or Petition 870250085418, dated 09 / 22 / 2025, page 28 / 78 19 / 55 In, tin oxide particle doped with P, Sb or As, indium oxide particle doped with Sn or Ge, titanium oxide particle doped and coated with zinc oxide doped with Al, Ga or In, titanium oxide particle doped and coated with tin oxide doped with P, Sb or As, and titanium oxide particle doped and coated with indium oxide doped with Sn or Ge.

[0048] From the point of view of increasing conductivity, the content of the dopant element is preferably from 0.05 to 5 atoms % and more preferably from 0.1 to 5 atoms % in relation to the undoped metal oxide.

[0049] The shape of the doped oxide particle is not particularly limited, however it is preferably a shape close to a sphere, for example, a spherical shape, a pseudo-spherical shape (e.g., an oblong shape, an ellipsoid shape, an oval shape, a rugby ball shape or similar) or a polyhedral shape (e.g., a football shape, (a truncated icosahedron shape), a die shape (a cubic shape), various brilliant faceted gem shapes or similar). Doped oxide particles exhibiting a shape close to a sphere tend to be uniformly dispersed throughout the coating film and, in this way, are more likely to uniformly form effective conduction paths that penetrate the coating film in the thickness direction throughout the coating film, thus further increasing the conductivity of the coating film.

[0050] As will be described below, a value (B / A) of the ratio of an average particle diameter (B) of the doped oxide particle to an average particle diameter (A) of the rust inhibitor pigment is preferably from 0.75 to 4.00. By establishing the value of the ratio between the average particle diameters within the range described above, it is easy to form an effective conduction path that penetrates the coating film in the thickness direction and sufficient conductivity can be imparted to the film. Petition 870250085418, dated 09 / 22 / 2025, page 29 / 78 20 / 55 coating.

[0051] The average particle diameter of the doped oxide particle is not particularly limited provided that the value of the ratio between the average particle diameters is within the above range and the lower limit of the average particle diameter is preferably 0.1 μm or more, more preferably 0.4 μm or more and particularly preferably 1.0 μm or more. In addition, the upper limit of the average particle diameter of the doped oxide particle is preferably 7.0 μm or less, more preferably 5.0 μm or less and particularly preferably 4.0 μm or less. By establishing the average particle diameter of the doped oxide particle within the range described above, it becomes easier to increase the conductivity of the coating film and the anchoring effect of the chemical conversion treatment layer.

[0052] In this report, the “average particle diameter” of the doped oxide particle refers to an average primary particle diameter when the doped oxide particles are present individually in the coating film and refers to an average secondary particle diameter representing particle diameters of the doped oxide particles in the aggregate state when the doped oxide particles are aggregated in the coating film. The average particle diameter of the doped oxide particle is calculated by the following cross-sectional observation. A cross-section of the surface-treated metal sheet in the thickness direction is mirror-polished and a cross-sectional image of the coating film is captured at a magnification of 5000 times with a scanning electron microscope (“JSM-7100F” manufactured by JEOL Ltd., acceleration voltage: 15 kV) (field of view: 24 µm x 18 µm).In the resulting backscattered electron image, 10 doped oxide particles with relatively large particle diameters are randomly selected. For each particle, an average value of the long-side and short-side lengths is measured using image processing software. Petition 870250085418, dated 09 / 22 / 2025, page 30 / 78 21 / 55 (Image J Ver. 1,54h) is calculated and used as the particle diameter. An arithmetic mean of the particle diameters of the 10 particles is calculated to obtain the average particle diameter. The same measurement is performed on 10 backscattered electron images, and the arithmetic mean of the backscattered electron images is used as the average particle diameter of the doped oxide particle.

[0053] The content of the doped oxide particle is 5% to 20% by volume, preferably 10% to 15% by volume relative to the coating film (total solids content of the coating film). That is, the lower limit of the doped oxide particle content is 5% by volume or more, preferably 10% by volume or more relative to the coating film (total solids content of the coating film). The upper limit of the doped oxide particle content is 20% by volume or less, preferably 15% by volume or less relative to the coating film (total solids content of the coating film). When the doped oxide particle content is less than 5% by volume, sufficient conductivity may not be imparted to the coating film. In addition, it is difficult to obtain the effect of increasing adhesion through the anchoring effect of the chemical conversion treatment layer formed on it.On the other hand, when the content of the doped oxide particle exceeds 20% by volume, the adhesion between the coating film and an electrodeposited film formed on the coating film may be reduced due to a reduction in the aggregation strength of the coating film. For example, the content of the doped oxide particle is preferably 15% by volume or less and may be less than 15% by volume.

[0054] The content of the doped oxide particle in the coating film is calculated by the following observation of the cross-section. Using image processing software (Image J), ​​the area occupied by the coating film and the area occupied by the doped oxide particle are measured for electron imaging. Petition 870250085418, dated 09 / 22 / 2025, page 31 / 78 22 / 55 backscattered images obtained by the same method as the method described above for measuring the average particle diameter of the doped oxide particle. Since the volume ratio of each component in the coating film corresponds approximately to the area ratio of the component when the cross-section of the coating film is observed, the measured area ratio of the doped oxide particle is used as a volume ratio of the doped oxide particle. The same measurement is performed on 10 backscattered electron images, and an arithmetic mean value of these is used as the content (% by volume) of the doped oxide particle. Rust Inhibiting Pigment

[0055] The rust inhibitor pigment increases the corrosion resistance of the surface-treated sheet metal, particularly the sheet metal surface adjacent to the coating film. The rust inhibitor pigment is not particularly limited, however preferably includes at least one member selected from the group consisting of a d-phosphate compound, a silicate compound, amorphous silica and a vanadate compound.

[0056] Phosphate compounds, silicate compounds, amorphous silica, and vanadate compounds can release silicate ions, phosphate ions, vanadate ions, or counter-cations of these anions (e.g., alkaline earth metal ions, Zn ions, Al ions, and the like) in an aqueous composition to form a coating film or on a coating film, according to changes in the surrounding environment. Among these ions, for example, phosphate ions react with metal ions of the metal sheet to form an insoluble film, thus suppressing corrosion. Silicate ions form an inorganic polymeric layer (barrier layer) on the surface of the metal sheet, thus protecting the metal sheet from corrosion factors. Vanadate ions form a film on the surface of the metal sheet, similarly to phosphate ions, and thus have a corrosion-suppressing effect. In addition, ions Petition 870250085418, dated 09 / 22 / 2025, page 32 / 78 23 / 55 exhibiting oxidizing properties, such as vanadate ions, are considered to further suppress corrosion by promoting the formation of the insoluble film described above or an inorganic polymeric layer. Corrosion resistance can be increased by adding one of these rust-inhibiting pigments (ions) separately, but when a plurality of these rust-inhibiting pigments are added in combination, they exhibit a composite effect, which can further increase corrosion resistance.

[0057] Examples of phosphate compounds include metal salts of orthophosphoric acid, polyphosphoric acid (a linear polymer of orthophosphoric acid having a degree of polymerization of up to 6 or a mixture of two or more types thereof), metaphosphoric acid (a cyclic polymer of orthophosphoric acid having a degree of polymerization of 3 to 6 or a mixture of two or more types thereof), tetrametaphosphoric acid and hexametaphosphoric acid; phosphorous pentoxide; phosphate minerals such as monetite, tufelite, whitlockite, xenotime, starkeyite, struvite and ranidite; commercially available phosphate pigments such as silica polyphosphoric acid or tripolyphosphate; metal salts of phytic acid, phosphonic acid (hypophosphorous acid) or phosphinic acid (diphosphorous acid); and mixtures of two or more types thereof. The orthophosphate here includes a monohydrogen phosphate (HPO42-) and a dihydrogen phosphate (H2PO4-) of orthophosphoric acid.In addition, the polyphosphate includes a hydrogen phosphate. The cation species that forms the phosphate is not particularly limited and is, for example, a metal ion such as Co, Cu, Fe, Mn, Nb, Ni, Sn, Ti, V, Y, Zr, Al, Ba, Ca, Mg, Sr or Zn or an oxo cation such as vanadyl, titanyl or zirconyl. Among these, the cation species that forms the phosphate is preferably Al, Ca, Mg, Mn or Ni. The phosphate compound may be used separately or in combination with two or more types thereof.

[0058] It is not preferable to use a large quantity of an alkali metal as a cation in the formation of phosphate. When an alkali metal phosphate is used, a Petition 870250085418, dated 09 / 22 / 2025, p. 33 / 78 24 / 55 The product obtained by sintering in an industrial manufacturing process tends to be excessively dissolved in water. However, when such an alkali metal phosphate is used, a slightly larger quantity of the alkali metal can be used when water solubility can be controlled during the production of the rust inhibitor pigment, the production of an aqueous composition for the formation of a coating film, the formation of a coating film on a metal sheet, the use of a metal sheet with surface treatment, or similar. Examples of such control include a method for controlling the elution rate in water by using the rust inhibitor pigment in conjunction with another additive that can suppress water solubility, or using the rust inhibitor pigment in conjunction with a highly cross-linked resin-based polymer or an inorganic polymer.

[0059] Examples of silicate compounds include silicates of an alkaline earth metal such as magnesium silicate or calcium silicate; silicates of an alkaline earth metal such as lithium silicate, sodium silicate or potassium silicate; aluminum silicate. Among these, lithium silicate, sodium silicate, and potassium silicate are, for example, lithium silicate in which the constitutional molar ratio of silicon dioxide (SiO2) and lithium oxide (Li2O) is 0.5 < (SiO2 / Li2O) < 8, sodium silicate in which the constitutional molar ratio of silicon dioxide (SiO2) and sodium oxide (Na2O) is 0.5 < (SiO2 / Na2O) < 4, potassium silicate in which the constitutional molar ratio of silicon dioxide (SiO2) and potassium oxide (K2O) is 0.5 < (SiO2 / K2O) < 4, and hydrates of these silicates.Specific examples of these include lithium orthosilicate (Li4SiO4; 2Li2O^SiO2), hexalithium orthodisilicate (Li6Si2O7; 3Li2O^2SiO2), lithium metasilicate (Li2SiOs; Li2O^SiO2), lithium disilicate (Li2Si2Os; Li2O^2SiO2), tetralithium heptasilicate (2Li2O^7SiO2), lithium tetrasilicate (Li2Si4O9; Li2O^4SiO2), tetralithium nonasilicate (2Li2O^9SiO2), tetralithium hexadecasilicate (2Li2O45SiO2), sodium orthosilicate (Na4SiO4; 2Na2O^SiO2), sodium metasilicate (Na2SiOs; Na2O^SiO2), disilicate of sodium. Petition 870250085418, dated 09 / 22 / 2025, page 34 / 78 25 / 55 (Na2Si2O5; Na2O^2SiO2), sodium tetrasilicate (Na2Si4O9; Na2O·4SiO2), potassium orthosilicate (K4S1O4; 2K2O-SiO2), potassium metasilicate (K2SO3; K2O·SiO2), potassium disilicate (K2S12O5; K2O-2SiO2), potassium tetrasilicate (K2S14O9; K2O-4S1O2) and hydrates of these silicates. Many of these silicate hydrates readily gel due to changes in the environment such as pH and temperature while remaining in the hydrated state and can partially polymerize to become a polysilicate. The silicate compound that can be applied in the present invention also includes such a polysilicate.

[0060] Examples of amorphous silica include amorphous silica exhibiting an oil absorption volume of 100 to 1000 ml / 100 g and a specific surface area of ​​200 to 1000 m² / g. The oil absorption volume of silica can be measured according to JIS K 5101-13-2. In addition, the specific surface area of ​​silica can be measured by a BET method.

[0061] Vanadate compounds are composite compounds in which the valence of vanadium is any one of 0, 2, 3, 4, or 5, or two or more valences, and are, for example, oxides, hydroxides, oxygen acid salts of various metals, compounds, halides, sulfates, metal powder, and the like of vanadate. These compounds decompose upon heating or in the presence of water and react with coexisting oxygen. For example, metal powder or a divalent vanadium compound is ultimately altered to any one of a trivalent, tetravalent, or pentavalent compound. A compound exhibiting a valence of 0, for example, a metallic vanadium powder, can be used for the reasons above, but are not practical given that there is a problem such as insufficient oxidation reaction. A pentavalent vanadium compound exhibits a vanadate ion and readily forms a heteropolymer that contributes to rust prevention by a heating reaction with a phosphate ion.Therefore, it is preferable to include a pentavalent vanadium compound as one of the components. Petition 870250085418, dated 09 / 22 / 2025, page 35 / 78 26 / 55 Specific examples of vanadium compounds include vanadium(II) compounds such as vanadium(II) oxide or vanadium(II) hydroxide, vanadium(III) compounds such as vanadium(III) oxide, vanadium(IV) compounds such as vanadium(IV) oxide or vanadyl halide, vanadium(V) compounds such as vanadium(V) oxide or vanadate (orthovanadate, metavanadate, pyrovanadate or similar compounds of various metals) and mixtures thereof. Preferred metal species in vanadate are the same as the metal species described for phosphate.

[0062] When an alkali metal vanadate is used, a product obtained by sintering in an industrial manufacturing process tends to be excessively soluble in water. Thus, similarly to the case of phosphate, it is not preferable to use a large quantity of an alkali metal vanadate. However, as with the use of alkali metal phosphate, the use of an alkali metal vanadate does not pose a problem as long as its solubility in water can be controlled. The same applies to the case of a vanadium halide or sulfate.

[0063] As described below, a value (B / A) of the ratio of an average particle diameter (B) of the doped oxide particle to an average particle diameter (A) of the rust inhibitor pigment is preferably from 0.75 to 4.00. By establishing the value of the ratio between the average particle diameters within the range described above, it is easy to form an effective conduction path that penetrates the coating film in the direction of thickness and sufficient conductivity can be imparted to the coating film.

[0064] The average particle diameter of the rust inhibitor pigment is not particularly limited provided that the value of the ratio between the average particle diameters is in the above range and the lower limit of the average particle diameter of the rust inhibitor pigment is preferably 0.2 μm or more, more preferably 0.5 μm or more and particularly preferably 1.0 μm or more. Petition 870250085418, dated 09 / 22 / 2025, page 36 / 78 27 / 55 In addition, the upper limit of the average particle diameter of the rust inhibitor pigment is preferably 5.0 μm or less, more preferably 4.0 μm or less, and particularly preferably 2.0 μm or less. By establishing the average particle diameter of the rust inhibitor pigment within the range described above, it becomes easier to further increase the conductivity of the coating film.

[0065] In this report, the “average particle diameter” of the rust inhibitor pigment refers to an average primary particle diameter when rust inhibitor pigment particles are present individually in the coating film and refers to an average secondary particle diameter representing the particle diameters of the rust inhibitor pigment in the aggregated state when the rust inhibitor pigment particles are aggregated in the coating film. The average particle diameter of the rust inhibitor pigment is calculated by the following cross-sectional observation. In the backscattered electron image obtained by the same method as the method described above for measuring the average particle diameter of the doped oxide particle, 10 rust inhibitor pigment particles exhibiting relatively large particle diameters are randomly selected.For each particle, an average value of the long-side and short-side lengths measured using image processing software (Image J) is calculated and used as the particle diameter. An arithmetic mean of the particle diameters of the 10 particles is calculated to obtain the average particle diameter. The same measurement is performed on 10 backscattered electron images, and an arithmetic mean of the backscattered electron images is used as the average particle diameter of the rust inhibitor pigment.

[0066] As will be discussed below, in the metal sheet with surface treatment according to the present embodiment, the thickness of the coating film is reduced in order to achieve a satisfactory conductivity of the coating film. Petition 870250085418, dated 09 / 22 / 2025, page 37 / 78 28 / 55 From the point of view of providing sufficient corrosion resistance to the surface-treated sheet metal, even in a thin coating film, the rust inhibitor pigment content is 20% to 50% by volume relative to the coating film (total solids content of the coating film). When the rust inhibitor pigment content is less than 20% by volume, corrosion resistance may be insufficient. When the rust inhibitor pigment content exceeds 50% by volume, the processability of the coating film and its aggregation strength may be reduced. For example, the rust inhibitor pigment content is preferably 25% by volume or more, it can be 30% by volume or more, and it can be more than 30% by volume. The rust inhibitor pigment content is preferably 45% by volume or less.

[0067] The rust inhibitor pigment content in the coating film is calculated by the following cross-sectional observation. Using image processing software (Image J), ​​the area occupied by the coating film and the area occupied by the rust inhibitor pigment are measured for a backscattered electron image obtained by the same method as the method described above for measuring the average particle diameter of the doped oxide particle. Since the volume ratio of each component in the coating film corresponds approximately to the component's area ratio when the cross-section of the coating film is observed, the measured area ratio of the rust inhibitor pigment is used as a volume ratio of the rust inhibitor pigment.The same measurement is performed on 10 backscattered electron images, and the arithmetic mean of these is used as the content (% by volume) of the rust inhibitor pigment. Ratio between the average particle diameters of the doped oxide particle and rust-inhibiting pigment.

[0068] As written above, the coating film includes the doped oxide particle Petition 870250085418, dated 09 / 22 / 2025, page 38 / 78 29 / 55 to impart conductivity and the rust inhibitor pigment to impart corrosion resistance. Here, when the doped oxide particle cannot form effective conduction paths that penetrate the coating film in the direction of the coating film thickness, it is not possible to impart appropriate conductivity to the coating film. From this point of view, in the metal sheet with surface treatment according to the present embodiment, a value (B / A) of the ratio of an average particle diameter (B) of the doped oxide particle to an average particle diameter (A) of the rust inhibitor pigment is from 0.75 to 4.00, preferably 1.00 or more and preferably 3.00 or less.

[0069] FIG. 2A is a schematic view illustrating a cross-section of the coating film with the (B / A) value of the average particle diameter ratio being 2.40 and FIG. 2B is a schematic view illustrating a cross-section of the coating film with the (B / A) value of the average particle diameter ratio being 0.42. As illustrated in FIG. 2A, when the (B / A) value of the average particle diameter ratio is within a range of 0.75 to 4, that is, when the doped oxide particles (124) are relatively large in relation to the rust inhibitor pigment (126), the doped oxide particle (124) can efficiently form effective conduction paths (E) that penetrate the coating film (120) in the thickness direction. On the other hand, as illustrated in FIG.2B, when the value (B / A) of the ratio between the average particle diameters is less than 0.75, that is, when the doped oxide particles (124) are considerably small (smaller than a predetermined ratio) in relation to the rust inhibitor pigment (126), the arrangement of the doped oxide particles (124) in the direction of the coating film thickness (120) is impeded by the rust inhibitor pigment (126) and the efficient formation of effective conduction paths (E) that penetrate the coating film (120) in the thickness direction is not possible. When the value (B / A) of the ratio between... Petition 870250085418, dated 09 / 22 / 2025, page 39 / 78 30 / 55 the average particle diameters exceed 4.00, the doped oxide particles may detach and corrosion resistance may be reduced.

[0070] Here, FIGS. 3A to 3G and FIGS. 4A to 4G illustrate the results of the EPMA analysis of a coating film formed on the surface of the hot-dip galvanized layer of the alloy (Zn-10 wt% Fe). The coating film includes doped oxide particles (Al-doped zinc oxide particle) and a rust-inhibiting pigment (amorphous silica, Mg-containing phosphate, and Al-containing phosphate). In FIGS. 3A to 3G and FIGS. 4A to 4G, numerical reference 112 indicates a galvanizing layer (hot-dip galvanized layer of the alloy) and numerical reference 120 indicates a coating film.

[0071] FIGS. 3A to 3G are EPMA images of a cross-section of the coating film of a metal sheet with a surface treatment with a (B / A) ratio of 2.00 (corresponding to FIG. 2A). FIG. 3A is a backscattered electron image (composite image) of the cross-section of the coating film, FIG. 3B is an element mapping image of Fe, FIG. 3C is an element mapping image of Zn, FIG. 3D is an element mapping image of P, FIG. 3E is an element mapping image of Mg, FIG. 3F is an element mapping image of Si, and FIG. 3G is an element mapping image of Al.

[0072] FIGS. 4A to 4G are EPMA images of a cross-section of the coating film of a metal sheet with a surface treatment with a particle mean diameter ratio (B / A) of 0.50 (corresponding to FIG. 2B). FIG. 4A is a backscattered electron image (composite image) of the cross-section of the coating film, FIG. 4B is an element mapping image of Fe, FIG. 4C is an element mapping image of Zn, FIG. 4D is an element mapping image of P, FIG. 4E is a mapping image Petition 870250085418, dated 09 / 22 / 2025, page 40 / 78 31 / 55 of the Mg element, FIG. 4F is a Si element mapping image and FIG. 4G is an Al element mapping image.

[0073] As is clear from FIGS. 3A, 3Ce and 3G, in the metal sheet with surface treatment illustrated in FIGS. 3A to 3G, the doped oxide particles (ZnO) (124) doped with a dopant element (Al) are close to both surfaces (both the upper surface and the lower surface) of the coating film (120). These doped oxide particles (124) are considered to function as conduction paths. On the other hand, as is clear from FIGS. 4A, 4C and 4G, in the metal sheet with surface treatment illustrated in FIGS. 4A to 4G, the doped oxide particles (ZnO) (124) doped with a dopant element (Al) are separated by a large distance from at least one of the two surfaces (the upper surface and the lower surface) of the coating film (120). There is a high possibility that these doped oxide particles (124) cannot function as conduction pathways.

[0074] As can be seen by comparing FIGS.3A, 3C and 3G with FIGS. 4A, 4C and 4G, it is considered that, by appropriate control of the (B / A) value of the ratio between the average particle diameters, it is easy to form an effective conduction path that penetrates the coating film in the direction of thickness and sufficient conductivity can be imparted to the coating film.

[0075] EPMA images were obtained by the following measurement method. In the same manner as the SEM measurement described above, a cross-section of the coating film is observed with an SEM attached to an EPMA apparatus (“JXA-iHP200F” manufactured by JEOL Ltd., measurement conditions: acceleration voltage of 15 kV, irradiation current of 3 χ 10-8 A) and an EPMA image was obtained by performing elemental analysis for each element of Fe, Zn, P, Mg, Si and Al. FIGS. 3A and 4A are presentations of the results of the elemental analysis. Other additives Petition 870250085418, dated 09 / 22 / 2025, page 41 / 78 32 / 55

[0076] The coating film may additionally contain another additive. The additional additive is, for example, a known additive such as an extender pigment, a solid lubricant and / or a leveling agent.

[0077] Examples of extender pigments include titania and zirconia.

[0078] Solid lubricant can impart excellent slip properties to the coating film and can increase spray resistance. Examples of solid lubricant include polyolefin waxes or paraffin waxes such as polyethylene wax, synthetic paraffin, natural paraffin, micro wax and chlorinated hydrocarbon; and fluororesin-based waxes such as a polyfluoroethylene resin (such as a polytetrafluoroethylene resin), a polyvinyl fluoride resin and a polyvinylidene fluoride resin.

[0079] The average particle diameter of the solid lubricant is not particularly limited, however it is preferably from 0.05 to 4 μm. When the average particle diameter of the solid lubricant is less than 0.05 μm, due to surface enrichment of the lubricant, the area occupied by the lubricant in the surface layer of the coating film will more likely be increased, which may reduce the adhesion between the coating film and a deposited film formed on the coating film. On the other hand, when the average particle diameter of the solid lubricant exceeds 4 μm, the lubricant will more likely detach from the coating film resin, making it difficult to obtain the expected sliding properties and corrosion resistance may be reduced.From the point of view of obtaining the adhesiveness of a coating material, corrosion resistance, sliding properties and spray resistance, the average particle diameter of the solid lubricant is most preferably from 0.1 to 3 µm and even more preferably from 0.3 to 2 µm.

[0080] The softening point of the solid lubricant is preferably from 100°C to 135°C and more preferably from 110°C to 130°C. When the softening point of Petition 870250085418, dated 09 / 22 / 2025, p. 42 / 78 33 / 55 solid lubricant and from 100°C to 135°C, the sliding properties and resistance to spraying are further increased.

[0081] The solid lubricant content is preferably from 0.1% to 10% by mass relative to the coating film (total solids content of the coating film). When the solid lubricant content is less than 0.1% by mass, sufficient sliding properties may not be obtained. When the solid lubricant content exceeds 10% by mass, the adhesion between the coating film and a deposited film formed on the coating film, and the corrosion resistance, may be reduced.

[0082] From the point of view of adhesion between the coating film and the deposited film, sliding properties and corrosion resistance, the solid lubricant content is more preferably from 0.2% to 5% by mass and even more preferably from 0.5% to 2.5% by mass in relation to the coating film (total solids content of the coating film). Coating film thickness

[0083] In the metal sheet with surface treatment according to the present embodiment, the coating film thickness is from 0.5 to 5.0 μm from the point of view of the possibility of resistance welding and electrodeposition coating while achieving satisfactory corrosion resistance. Here, when a doped oxide particle and / or a rust inhibitor pigment particle project from the surface of the coating film, the coating film thickness is a thickness of one part where the doped oxide particle and / or the rust inhibitor pigment particle do not project from the surface of the coating film. When the coating film thickness is less than 0.5 μm, the adhesion between the coating film and an electrodeposited film formed on the surface of the coating film and the corrosion resistance may not be sufficiently obtained. On the other hand, when the thickness of the Petition 870250085418, dated 09 / 22 / 2025, page 43 / 78 34 / 55 coating film exceeds 5 μm, the conductivity of the coating film may be reduced, making resistance welding and electrodeposition coating difficult, and the adhesion strength of the coating film may be reduced. For example, the coating film thickness is preferably 3.0 μm or less and may be less than 3.0 μm.

[0084] The coating film thickness is measured by the following cross-sectional observation. In a plurality of images (backscattered electron images) obtained by SEM measurement described above, 10 locations for measuring a film thickness are randomly selected such that the intervals between locations are 5 μm or more. The 10 selected locations can be chosen not only from a single image but also from a plurality of images measured in different observation regions (fields of view). An average value of the film thicknesses at 10 locations measured using image processing software (Image J) is calculated and used as the coating film thickness. The coating film thickness is the length of the coating film in a direction orthogonal to the surface of the metal sheet with surface treatment.The surface of the metal sheet with surface treatment here refers to a surface (primary surface) that extends over the entire metal sheet with surface treatment to be measured, rather than a microscopic strip on the order of several μm. Method for forming a coating film.

[0085] The method for forming the coating film is not particularly limited and a known method can be used. For example, a composition for forming a coating film is prepared by mixing a binder resin, doped oxide particles, a rust inhibitor pigment and, optionally, another additive in a solvent. The solvent can be water or an organic solvent, however, from the point Petition 870250085418, dated 09 / 22 / 2025, page 44 / 78 Considering manufacturing cost and environmental suitability, water is preferable. That is, the composition for forming a coating film is preferably an aqueous composition. Then, the composition for forming a coating film is applied to at least one surface of a metal sheet and dried and heated to form a coating film. Application

[0086] The applications of the surface-treated sheet metal (and a coated sheet metal obtained by coating the surface-treated sheet metal) according to the present embodiment are not particularly limited. For example, the surface-treated sheet metal and the coated sheet metal according to the present embodiment can be widely used for an automotive member (an automobile body, a gear or the like), a mechanical member (a housing or the like), a household appliance member (a casing or the like), a building material (a roof, a wall or the like) and the like. Effect

[0087] In the metal sheet with surface treatment according to the present embodiment, doped oxide particles exhibiting conductivity are added to the coating film, a value (B / A) of the ratio of an average particle diameter (B) of the doped oxide particle to an average particle diameter (A) of a rust inhibitor pigment added to the coating film is set to 0.75 to 4.00, and the thickness of the coating film is reduced. In this way, in the metal sheet with surface treatment according to the present embodiment, the conductivity of the coating film is increased. Thus, the metal sheet with surface treatment according to the present embodiment is suitable not only for resistance welding but also for electrodeposition coating. On the other hand, when Petition 870250085418, dated 09 / 22 / 2025, page 45 / 78 36 / 55 The thickness of a coating film is reduced in this way, the corrosion resistance will most likely be reduced; however, in the sheet metal with surface treatment according to the present embodiment, the amount of rust-inhibiting pigment added to the coating film is increased. As a result, the sheet metal with surface treatment according to the present embodiment maintains sufficient corrosion resistance while achieving satisfactory conductivity of the coating film.

[0088] In addition, in the metal sheet with surface treatment according to the present embodiment, doped oxide particles are used as conductive particles in the coating film. That is, in the metal sheet with surface treatment according to the present embodiment, expensive non-oxide ceramic particles do not necessarily need to be used as the conductive particles. In this way, the metal sheet with surface treatment according to the present embodiment can be manufactured at a lower cost than a conventional metal sheet with surface treatment containing non-oxide ceramic particles. Automotive member

[0089] Next, an automotive member according to an embodiment of the present invention will be described.

[0090] The automotive member according to the present embodiment is an automotive member comprising a coated sheet metal. The coated sheet metal includes sheet metal with surface treatment according to the embodiment described above, a chemical conversion treatment layer disposed on the surface of the coating film of the sheet metal with surface treatment and an electrodeposited film disposed on the surface of the chemical conversion treatment layer. The automotive member is, for example, a member for an automobile body, a member for a gear or the like. Petition 870250085418, dated 09 / 22 / 2025, page 46 / 78 37 / 55 Coated metal sheet

[0091] FIG. 5 is a schematic view (partial enlarged cross-sectional view of an automotive member) illustrating a cross-section of a coated metal sheet according to the embodiment of the present invention. In the example illustrated in FIG. 5, the coated metal sheet (200) includes the metal sheet (110), coating film (120) disposed on the surface of the metal sheet (110), chemical conversion treatment layer (210) disposed on the surface of the coating film (120) and electrodeposited film (220) disposed on the surface of the chemical conversion treatment layer (210). In this example, the chemical conversion treatment layer (210) is a discontinuous layer composed of a large number of crystals (212) of an acid salt precipitated on the surface of the coating film (120).

[0092] The surface-treated metal sheet can be molded into a predetermined shape depending on the applications. In addition, a plurality of surface-treated metal sheets can be joined by welding, adhesion, or similar means. The surface-treated metal sheet according to the present embodiment exhibits excellent conductivity of the coating film, such that defects such as cracking due to welding are less likely to occur, and a deposited film can be formed by electrodeposition coating. Chemical conversion treatment layer

[0093] A chemical conversion treatment layer is a layer located on the surface of the coating film and formed by performing a chemical conversion treatment on the surface of the coating film. The chemical conversion treatment layer can be a continuous layer covering the surface of the treated steel sheet without gaps, or it can be a discontinuous layer intermittently covering the surface of the treated steel sheet. Representative examples of such a chemical conversion treatment layer include a layer Petition 870250085418, dated 09 / 22 / 2025, page 47 / 78 38 / 55 of an acid salt such as a phosphate layer. A chemical conversion treatment liquid for the formation of such an acid salt layer is acidic (e.g., pH 2 to 3), and the doped oxide particle exhibits a property such that the doped oxide particle dissolves in an acidic chemical conversion treatment liquid. Thus, when the steel sheet with a surface treated according to the present embodiment is subjected to a chemical conversion treatment using an acidic chemical conversion treatment liquid, the doped oxide particles in the surface layer of the coating film are dissolved, and the pH in their vicinity increases. A component of the chemical conversion treatment liquid (e.g., an acid salt such as a phosphate) is thus precipitated and grown in a location where the doped oxide particles are dissolved.As a result, the chemical conversion treatment liquid component is considered to grow into a wedge shape to project from the interior of the surface layer of the coating film to the surface. As illustrated in FIG. 5, when the electrodeposited film (220) is formed by electrodeposition coating on the surface of the chemical conversion treatment layer (210) (discontinuous layer composed of crystals (212) of the acid salt) in this state, the adhesion between the coating film and the electrodeposited film (220) is further increased by an anchoring effect of the wedge-shaped crystals (212) of the acid salt, in addition to the high adhesion due to the chemical properties of the acid salt.

[0094] Examples of phosphate include crystalline phosphate and amorphous phosphate. From the point of view of placing the phosphate in wedge form in the chemical conversion treatment layer, crystalline phosphate is preferable. Examples of crystalline phosphate include zinc phosphate (hopite: Zns(PO4)2^4H2O), zinc iron phosphate (phosphophyllite: Zn2Fe(PO4)2^4H2O), manganese phosphate (hureaulite: Mns(POs(OH))2(PO4)2 4H2O), manganese iron phosphate ((Mni-xFex)sH2(PO4)4^4H2O, where x represents the material Petition 870250085418, dated 09 / 22 / 2025, page 48 / 78 39 / 55 Iron-based metallic material is pickled during chemical conversion treatment, and the iron component is contained within the film; 0 <x<1), e fosfato de cálcio zinco (scholzita: CaZm(PO4)2^2H2O). Exemplos do fosfato amorfo incluem fosfato de ferro, fosfato de estanho, fosfato de zircônio, fosfato de titânio e fosfato de háfnio.

[0095] In addition, the chemical conversion treatment layer may be composed of components other than phosphate. For example, the chemical conversion treatment layer may contain a salt of at least one member selected from iron, titanium, zirconium, hafnium, indium, tin, bismuth, vanadium, nickel, cerium, molybdenum, and tungsten and a nitrate ion, a sulfate ion, a fluoride ion, a complex fluoride ion, or a carbonate ion. Examples of such a salt include titanium oxide, zirconium oxide, hafnium oxide, indium oxide, tin oxide, bismuth oxide, vanadium oxide, nickel oxide, cerium oxide, molybdenum oxide, tungsten oxide, iron sulfide, zirconium fluoride, titanium fluoride, hafnium fluoride, and indium fluoride.

[0096] The thickness of the chemical conversion treatment layer is not particularly limited, however it is preferably from 0.01 μm to 3 μm, more preferably from 0.03 μm to 2 μm and even more preferably from 0.05 μm to 1 μm. When the chemical conversion treatment layer includes a crystalline salt, since the chemical conversion treatment layer presents irregularities due to the crystals, it is not appropriate to discuss its thickness. On the other hand, the crystal diameter of the chemical conversion treatment layer can be noted. The crystal diameter of the crystalline phosphate is preferably from 0.10 to 5 μm, more preferably from 0.30 to 4 μm and even more preferably from 0.50 to 3 μm. electrodeposited film

[0097] The electrodeposited film is applied to the metal sheet with a surface treatment layer of chemical conversion treatment between it. The electrodeposited film is a film formed by electrodeposition coating. The film Petition 870250085418, dated 09 / 22 / 2025, page 49 / 78 40 / 55 deposited may be a single layer or a multiple layer (e.g., a deposited film composed of a bottom coating layer, an intermediate coating layer, and a top coating layer). The coated metal sheet according to the present embodiment may be coated by other coating treatments such as powder coating and solvent coating, other than electrodeposition coating. Method for manufacturing automotive parts

[0098] The automotive member according to the present embodiment can be manufactured, in one step of forming a chemical conversion treatment layer on the surface of a coating film of a metal sheet with surface treatment (first step) and one step of forming an electrodeposited film on the surface of the chemical conversion treatment layer (second step).

[0099] First, before the first stage, the sheet metal with the surface treatment described above is prepared. The sheet metal with the surface treatment can be shaped into a predetermined form. The shaping of the sheet metal with the surface treatment can be carried out using, for example, a molding technique known as cutting or pressure molding. In addition, a plurality of the sheet metal with the surface treatment or the molded materials can be joined by welding (e.g., spot welding) or similar. In addition, the sheet metal with the surface treatment can be subjected to a pre-treatment known as degreasing or surface adjustment.

[0100] In the first stage, the metal sheet with surface treatment is subjected to a chemical conversion treatment to form a chemical conversion treatment layer on the surface of the coating film. A chemical conversion treatment liquid and the treatment conditions for the chemical conversion treatment can be selected appropriately depending on the state and composition of the layer. Petition 870250085418, dated 09 / 22 / 2025, page 50 / 78 41 / 55 chemical conversion treatment to be formed.

[0101] For example, when the chemical conversion treatment layer includes a crystalline phosphate, an acidic aqueous solution that includes phosphate ion as an anion and at least one selected member of zinc, calcium, and manganese as a cation can be used as the chemical conversion treatment liquid. In order to increase the reaction rate, it is preferable that a transition metal ion such as nickel or cobalt, an oxidizing agent such as nitric acid or nitrous acid, and a pickling component such as a fluoride ion or fluoride complex ion are added to the acidic aqueous solution. As the acidic aqueous solution described above for phosphate treatment, in which the types and contents of the anion and cation are appropriately combined, commercially available acidic aqueous solutions can be used as is.Examples of commercially available acidic aqueous solutions for phosphate treatment include “PALBOND 860”, “PALBOND L3020”, “PALFOS M1A”, “PALFOS M5”, “PALBOND 880”, “PALBOND SX35”, “PALBOND L47” and “FERROCOAT 7” manufactured by Nihon Parkerizing Co., Ltd. The pH of the chemical conversion treatment liquid described above is not particularly limited, however it is preferably from 1.0 to 5.0 and more preferably from 2.0 to 4.0.

[0102] The temperature during the chemical conversion treatment using the chemical conversion treatment liquid described above is not particularly limited, however it is preferably from 30°C to 120°C, more preferably from 35°C to 110°C, and even more preferably from 40°C to 100°C. The chemical conversion treatment time is not particularly limited and can be appropriately selected depending on the target amount of adhesion of the chemical conversion treatment layer to be formed.

[0103] In addition, when the chemical conversion treatment layer includes an amorphous phosphate, for example, an acidic aqueous solution that includes phosphate ions as a Petition 870250085418, dated 09 / 22 / 2025, page 51 / 78 42 / 55 anions and at least one selected member of iron, tin, zirconium, titanium, and hafnium as a cation can be used as the chemical conversion treatment liquid. To increase the reaction rate, it is preferable that transition metal ions such as nickel or cobalt, an oxidizing agent such as nitric acid or nitrous acid, and a pickling component such as fluoride ion or fluoride ion complex are added to the acidic aqueous solution. As the acidic aqueous solution described above for phosphate treatment, in which the types and contents of the anion and cation are appropriately combined, commercially available acidic aqueous solutions as is can be used. Examples of commercially available acidic aqueous solutions for phosphate treatment include “PALFOS 1077”, “PALFOS 525T”, and “PALFOS K5100” manufactured by Nihon Parkerizing Co., Ltd.The pH of the chemical conversion treatment liquid described above is not particularly restricted, however it is preferably from 1.0 to 5.0 and more preferably from 2.0 to 4.0.

[0104] In addition, as a chemical conversion treatment liquid for the formation of another chemical conversion treatment layer, an acidic aqueous solution containing the following may be used: at least one member selected from a nitrate ion, a sulfate ion, a fluoride ion, a fluoride complex ion, and a carbonate ion as an anion; and at least one member selected from iron, titanium, zirconium, hafnium, indium, tin, bismuth, vanadium, nickel, cerium, molybdenum, and tungsten as a cation. Such an acidic aqueous solution may be prepared by the appropriate combination of the types of compounds corresponding to the anions and cations described above, or commercially available acidic aqueous solutions may be used as is. The pH of the chemical conversion treatment liquid described above is not particularly limited, however it is preferably from 1.0 to 5.0 and more preferably from 2.0 to 4.0.

[0105] In a case of forming a chemical conversion treatment layer Petition 870250085418, dated 09 / 22 / 2025, page 52 / 78 43 / 55 containing amorphous phosphate or another chemical conversion treatment layer, the temperature during the chemical conversion treatment using the chemical conversion treatment liquid is not particularly limited, however it is preferably from 10°C to 100°C, more preferably from 15°C to 80°C and even more preferably from 20°C to 60°C. The time of the chemical conversion treatment is not particularly limited and can be appropriately selected depending on the target amount of adhesion of the chemical conversion treatment layer to be formed.

[0106] In the second stage, the metal sheet with surface treatment that has undergone chemical conversion treatment is subjected to electrodeposition coating. The electrodeposition coating conditions are not particularly limited and, for example, the electrodeposited film can be formed on the coating film of the metal sheet with surface treatment by the following steps: electrodeposition coating of a cationic electrodeposition coating material at a voltage of 160 V and baking of the coating material at a baking temperature of 170°C for 20 minutes. A plurality of layers of the electrodeposited film can be formed by performing the electrodeposition coating a plurality of times.

[0107] Through these steps, the automotive member according to the present embodiment can be manufactured. Effect

[0108] In the automotive member according to the present embodiment, since the surface-treated metal sheet includes a conductive coating film, a deposited film is appropriately formed by electrodeposition coating, resulting in excellent adhesion between the coating film and the electrodeposited film. In addition, since the surface-treated metal sheet according to the present embodiment is also suitable for Petition 870250085418, dated 09 / 22 / 2025, page 53 / 78 44 / 55 resistance welding, even when surface-treated or coated sheet metal is welded, avoids defects such as welding cracks.

[0109] Hereafter, the present invention will be described in detail with reference to examples; however, the present invention is not limited to these examples. Examples

[0110] Sheet metal manufacturing with surface treatment 1. Preparation of the metal sheet The two types of zinc-based galvanized steel sheets were prepared, and the surface of each sheet was degreased by immersion in a 2.5% by mass aqueous solution of an aqueous alkaline degreasing agent (FC-301, manufactured by Nihon Parkerizing Co., Ltd.) at 40°C for 2 minutes, followed by rinsing with water and drying to prepare and obtain a base material to be coated. GA: hot-dip galvanized steel sheet (Zn-10% Fe by mass) (sheet thickness: 0.8 mm, coating adhesion quantity: 45 g / m2) GI: hot-dip galvanized steel sheet (sheet thickness: 0.8 mm, coating adhesion quantity: 60 g / m2) 2. Preparation of the aqueous composition

[0111] In order to form each coating film exhibiting the composition shown in Tables 1 to 4, the components were mixed to have the same concentration of solid contents as those shown in Tables 1 to 4, thus preparing a corresponding aqueous composition for the formation of the coating film.

[0112] In Tables 1 to 4, the concentration (Conc. in tables) of the solid content of each component is described as the ratio (unit: % by volume) of the solid content (non-volatile contents) of each component to the solid content (non-volatile contents). Petition 870250085418, dated 09 / 22 / 2025, page 54 / 78 45 / 55 volatile compounds) of the entire aqueous composition.

[0113] Details of the components (symbol) in Tables 1 to 4 are as follows.

[0114] (A) Binder resin E: Epoxy resin emulsion (ADEKA RESIN (registered trademark) EM-0718, ADEKA Corporation) U: Urethane resin emulsion (SUPERFLEX (registered trademark) E-2000, DKS Co., Ltd.) P: Polyester resin emulsion (VYLONAL (registered trademark) MD-2000, Toyobo Co., Ltd.)

[0115] (B) Doped oxide particle Zn 1: Zinc oxide (ZnO) particles doped with Al (23-K, manufactured by HAKUSUI TECH CO., LTD.) Zn 2: Zinc oxide (ZnO) particles doped with Ga (Pazet GK-40, manufactured by HAKUSUI TECH CO., LTD.) Sn 1: P-doped tin oxide (SnO) particles (SP-2, Mitsubishi Materials Electronic Chemicals Co., Ltd.) Sn 2: Tin oxide (SnO) particles doped with Sb (SN-100P, Ishihara Sangyo Kasha, Ltd.) In: indium oxide (In2O3) particles doped with Sn (E-ITO, Mitsubishi Materials Electronic Chemicals Co., Ltd.) Ti: Titanium oxide (TiO2) particles coated with Sb-doped tin oxide (SnO2) (EC-210, Titan Kogyo, Ltd.)

[0116] (C) Rust inhibitor pigment PAM: Mg-containing aluminum dihydrogen tripolyphosphate (K-WHITE G105, manufactured by TAYCA Corporation) PA: aluminum dihydrogen tripolyphosphate (K-WHITE K105, manufactured by Petition 870250085418, dated 09 / 22 / 2025, page 55 / 78 46 / 55 TAYCA Corporation Si: silicon dioxide (amorphous silica) (SNOWTEX (registered trademark) ZL, Nissan Chemical Corporation) V: vanadium pentoxide (Kanto Chemical Co., Inc.)

[0117] The various doped oxide particles were utilized by dispersing the doped oxide particles in water containing a resin sprayed by a ball mill. The average particle diameter of the doped oxide particle was adjusted by controlling the spraying time. The average particle diameter of the doped oxide particle in the coating film was measured by the following procedure after manufacturing a metal sheet with surface treatment as described above. A cross-section of the surface-treated metal sheet in the thickness direction was mirror-polished, and an image of the cross-section of the coating film was captured at a magnification of 5000 times with a scanning electron microscope (“JSM-7100F” manufactured by JEOL Ltd., accelerating voltage: 15 kV) (field of view: 24 μm x 18 μm).In the obtained backscattered electron image, 10 doped oxide particles with relatively large particle diameters were selected. For each particle, an average value of the long-side and short-side lengths measured using image processing software (Image J Ver. 1.54h) was calculated and used as the particle diameter. An arithmetic mean of the particle diameters of the 10 particles was calculated to obtain the average particle diameter. The same measurement was performed on 10 backscattered electron images, and an arithmetic mean of the backscattered electron images was used as the average particle diameter of the doped oxide particle. In addition, the average particle diameter of the rust inhibitor pigment in the coating film was also measured using the same procedure.

[0118] In addition, after the manufacture of the sheet metal with surface treatment Petition 870250085418, dated 09 / 22 / 2025, pp. 56 / 78 47 / 55 as described above, the contents (% by volume) of the doped oxide particle and the rust inhibitor pigment in the coating film were calculated using the following procedure, and the values ​​were found to be substantially the same as the concentrations (% by volume) of the doped oxide particle and the rust inhibitor pigment shown in Tables 1 to 4. Using image processing software (Image J), ​​the area occupied by the coating film, the area occupied by the doped oxide particle, and the area occupied by the rust inhibitor pigment were measured for the backscattered electron image obtained by the same method as the method described above for measuring the average particle diameter of the doped oxide particle.Since the volume ratio of each component in the coating film approximately corresponds to the component's area ratio when the cross-section of the coating film is observed, the measured area ratio of the doped oxide particle and the measured area ratio of the rust inhibitor pigment were used as the volume ratio of the doped oxide particle and the volume ratio of the rust inhibitor pigment, respectively. The same measurement was performed on the 10 backscattered electron images, and the arithmetic mean values ​​of these were used as the volume content (% by volume) of the doped oxide particle and the volume content (% by volume) of the rust inhibitor pigment. 3. Sheet metal manufacturing with surface treatment

[0119] In order to present the configuration of Tables 1 to 4, an aqueous composition was applied to a metal sheet with a bar coating and dried using an oven under conditions such that the temperature was maintained, reaching a maximum temperature of 140°C for 8 seconds to form a coating film. The film thickness of the coating film was adjusted to a numerical value shown in Tables 1 to 4 by diluting the aqueous composition and changing the number of the bar coating. The film thickness of the coating film was measured by the procedure Petition 870250085418, dated 09 / 22 / 2025, pp. 57 / 78 48 / 55 below. In the plurality of images (backscattered electron images) obtained by SEM measurement described above, 10 film thickness measurement locations were selected such that the intervals between locations are 5 μm or more. An average value of the film thicknesses at the 10 locations, measured using image processing software (Image J), ​​was calculated and used as the film thickness of the coating film. Assessment test 1. Evaluation of the appearance and adhesion of the electrodeposited film

[0120] Each metal sheet with surface treatment was subjected to electrodeposition coating with a cationic electrodeposition coating material (Nippon Paint Co., Ltd.) by slope energization at a voltage of 160 V and baked at 170°C for 20 minutes. The average film thickness of the deposited film after electrodeposition coating was 10.0 μm in all samples.

[0121] After electrodeposition coating was performed, the appearance of the electrodeposited film was visually observed and evaluated according to the following standards. When the evaluation result was “C”, the metal sheet with surface treatment with this evaluation was determined as not being suitable for electrodeposition coating. A: A uniform electrodeposited film was formed. B: A non-uniform electrodeposited film was formed. C: an electrodeposited film was not formed When a part was recognized as different from the other parts in terms of color tone, brightness, or similar characteristics during visual observation of the appearance (surface) of the electrodeposited film, the evaluation of the metal sheet with surface treatment was determined to be “B: a non-uniform electrodeposited film was formed”. When a part was not recognized as different from the other parts in Petition 870250085418, dated 09 / 22 / 2025, pp. 58 / 78 49 / 55 in terms of color tone, gloss, or similar, the evaluation of the metal sheet with surface treatment was determined to be “A: a uniform electrodeposited film was formed”. In addition, when no electrodeposited film was formed, the surface of the underlying metal sheet was visually recognized. The surface of the metal sheet can be identified as a metal sheet by metallic luster, a “spangle” type pattern, or similar.

[0122] Next, the electrodeposited film was subjected to salt spraying for 80 hours and then subjected to an adhesion test according to JIS K 5600-5-6 (2018) by a cross-cut method. Subsequently, on each surface-treated metal sheet, the proportion of the area where electrodeposited film peeling occurred to the test area (peel proportion (%) of the deposited film) was measured. From the peel proportion of the deposited film, the adhesion of the electrodeposited film was evaluated according to the following standards. When the evaluation result was “C”, the surface-treated metal sheet with this evaluation was determined as not being suitable for electrodeposition coating. A: the peeling rate was less than 5% B: the peeling rate was 5% or more and less than 15% C: the peeling rate was 15% or more 2. Corrosion resistance assessment

[0123] Each metal sheet with surface treatment that underwent electrodeposition coating was subjected to 90 cycles of a corrosion cycle according to JASO M 609. Then, the status of red rust occurrence was measured on each metal sheet with surface treatment and the proportion of red rust area (%) was calculated. From the proportion of red rust area, the corrosion resistance of the metal sheet with surface treatment was evaluated. Petition 870250085418, dated 09 / 22 / 2025, page 59 / 78 50 / 55 in accordance with the following standards. When the evaluation result was “C”, the corrosion resistance of the metal sheet with surface treatment with this evaluation was determined to be insufficient. AA: no red rust generation A: The proportion of the red rust area was greater than 0% and less than 10%. B: the proportion of the red rust area was 10% or more and less than 20% C: the proportion of the red rust area was 20% or more

[0124] Hereafter, the details of the Examples will be listed in Tables 1 to 4. The samples in which the “Observations” column in Tables 1 to 4 is blank correspond to the Examples. Petition 870250085418, dated 09 / 22 / 2025, pp. 60 / 78 51 / 55

[0125] Table 1 No. Metal plate Coating film Doped oxide particle Rust inhibitor pigment Value ratio between average particle diameters Electrodeposited film Corrosion resistance Observations Resin Thickness Film (Pm) Type Conc. (vol %) Diameter Pigment 1 Pigment 2 Oxide particle / Rust inhibitor pigment (pm / pm) Appearance Adhesion Average particle diameter (Pm) Type Conc. (vol %) Average particle diameter (Pm) Type Conc.(vol %) Mean particle diameter (Pm) 1 GA E 2.0 Zn 1 15 2.0 PA M 40 1.0 - - - 2.00 AAA 2 GI E 2.0 Zn 1 15 2.0 PA M 40 1.0 - - - 2.00 AAA 3 GA U 2.0 Zn 1 15 2.0 PA M 40 1.0 - - - 2.00 AAA 4 GA P 2.0 Zn 1 15 2.0 PA M 40 1.0 - - - 2.00 AAA 5 GA E 0.5 Zn 1 15 0.5 PA M 40 0.5 - - - 1.00 AAB 6 GA E 1.0 Zn 1 15 1.0 PA M 40 1.0 - - - 1.00 AAB 7 GA E 4.0 Zn 1 15 2.0 PA M 40 1.0 - - - 2.00 ABA 8 GA E 5.0 Zn 1 15 2.0 PA M 40 1.0 - - - 2.00 ABA 9 GA E 2.0 Zn 2 15 2.0 PA M 40 1.0 - - - 2.00 AAA 10 GA E 2.0 Sn 1 15 2.0 PA M 40 1.0 - - - 2.00 AAA 11 GA E 2.0 Sn 2 15 2.0 PA M 40 1.0 - - - 2.00 AAA 12 GA E 2.0 In 15 2.0 PA M 40 1.0 - - - 2.00 AAA 13 GA E 2.0 Ti 15 2.0 PA M 40 1.0 - - - 2.00 AA A. Petition 870250085418, 9 / 22 / 2025, p. 61 / 7 52 / 5

[0126] Table 2 No. Metal plate Coating film Doped oxide particle Rust inhibitor pigment Ratio value between average particle diameters Electrodeposited film Corrosion resistance Observations Resin Thickness Film (μm) Type Conc. (vol %) Average particle diameter (μm) Pigment 1 Pigment 2 Oxide particle / Rust inhibitor pigment (μm / μm) Appearance Adhesion Type Conc. (vol %) Average particle diameter (μm) Type Conc.(vol %) Mean particle diameter (μm) 14 GA E 2.0 Zn 1 5 2.0 PA M 40 1.0 - - - 2.00 ABA 15 GA E 2.0 Zn 1 10 2.0 PA M 40 1.0 - - - 2.00 AAA 16 GA E 2.0 Zn 1 20 2.0 PA M 40 1.0 - - - 2.00 AAA 17 GA E 2.0 Zn 1 15 0.5 PA M 40 0.5 - - - 1.00 AAA 18 GA E 2.0 Zn 1 15 1.0 PA M 40 1.0 - - - 1.00 AAA 19 GA E 4.0 Zn 15 4.0 PA M 40 2.0 - - - 2.00 AAA 20 GA E 2.0 Zn 1 15 2.0 PA 40 1.0 - - - 2.00 AAA 21 GA E 2.0 Zn 1 15 2.0 Si 40 1.0 - - - 2.00 AAA 22 GA E 2.0 Zn 15 2.0 V 40 1.0 - - - 2.00 AAA 23 GA E 2.0 Zn 1 15 2.0 PA M 20 1.0 - - - 2.00 AAA 24 GA E 2.0 Zn 1 15 2.0 PA M 30 1.0 - - - 2.00 AAA 25 GA E 2.0 Zn 1 15 2.0 PA M 50 1.0 - - - 2.00 ABA 26 GA E 2.0 Zn 1 15 2.0 PA M 20 1.0 Si 20 1.0 2.00 AA AA. Petition 870250085418, 9 / 22 / 2025, p. 62 / 7 53 / 5

[0127] Table 3 No. Metal plate Coating film Doped oxide particle Rust inhibitor pigment Ratio value between average particle diameters Electrodeposited film Corrosion resistance Observations Resin Thickness Film (μm) Type Conc. (vol %) Average particle diameter (μm) Pigment 1 Pigment 2 Oxide particle / Rust inhibitor pigment (μm / μm) Appearance Adhesion Type Conc. (vol %) Average particle diameter (μm) Type Conc.(vol %) Diam etro médio de partíc ula (μm) 2 7 GA E 2,0 Zn 1 15 2,0 PA M 20 1,0 V 20 1,0 2,00 AA AA 2 8 GA E 2,0 Zn 1 15 2,0 PA 20 1,0 Si 20 1,0 2,00 AA AA 2 9 GA E 2,0 Zn 1 15 2.0 PA 20 1.0 V 20 1.0 2.00 AA AA 3 0 GA E 2.0 Zn 1 15 2.0 Si 20 1.0 V 20 1.0 2.00 AA AA 3 1 GA E 2.0 Zn 1 15 2.0 PA M 10 1.0 Si 10 1.0 2.00 AA AA 3 2 GA E 2,0 Zn 1 15 2,0 PA M 10 1,0 Si 20 1,0 2,00 AA AA 3 3 GA E 2,0 Zn 1 15 2,0 PA M 10 1,0 Si 40 1,0 2,00 AA AA 3 4 GA E 2,0 Zn 1 15 2,0 PA M 20 1,0 Si 10 1,0 2,00 AA AA 3 5 GA E 2,0 Zn 1 15 2,0 PA M 40 1,0 Si 10 1,0 2,00 AA AA 3 6 GA E 2,0 Zn 1 15 2,0 PA M 20 1,0 V 10 1,0 2,00 AA AA 3 7 GA E 2,0 Zn 1 15 2,0 PA M 40 1,0 V 10 1,0 2,00 AA AA 3 8 GA E 4,0 Zn 1 15 1,5 PA M 40 2,0 - - - 0,75 BBA 3 9 GA E 4,0 Zn 1 15 4,0 PA M 40 4,0 - - - 1,00 AA A. Petition 870250085418, de 22 / 09 / 2025, pág. 63 / 78 54 / 55

[0128] Table 4 No. Metal plate Coating film Doped oxide particle Rust inhibitor pigment Ratio value between average particle diameters Electrodeposited film Corrosion resistance Observations Resin Thickness Film (gm) Type Conc. (vol %) Average particle diameter (gm) Pigment 1 Pigment 2 Oxide particle / Rust inhibitor pigment (gm / gm) Appearance Adhesion Type Conc. (vol %) Average particle diameter (gm) Type Conc.(vol %) Average particle diameter (gm) 40 GA E 4.0 Zn 1 15 2.0 PA M 40 0.5 - - - 4.00 AAB 41 GA E 4.0 Zn 1 15 4.0 PA M 40 1.0 - - - 4.00 AAB 42 GA E 5.0 Zn 1 15 5.0 PA M 40 4.0 - - - 1.25 AAB 43 GA E 5.0 Zn 1 15 4.0 PA M 40 5.0 - - - 0.80 BBA 44 GA E 1.0 Zn 1 15 1.0 PA M 40 0.4 - - - 2.50 AAB 45 GA E 0.4 Zn 1 15 0.4 PA M 40 0.4 - - - 1.00 AAC Comparative Example 46 GA E 2.0 Zn 1 15 2.0 PA M 40 0.4 - - - 5.00 AAC Comparative Example 47 GA E 6.0 Zn 1 15 2.0 PA M 40 1.0 - - - 2.00 CCA Comparative Example 48 GA E 2.0 Zn 1 4 2.0 PA M 40 1.0 - - - 2.00 CCA Comparative Example 49 GA E 2.0 Zn 1 21 2.0 PA M 40 1.0 - - - 2.00 AAC Comparative Example 50 GA E 5.0 Zn 1 15 5.0 PA M 40 1.0 - - - 5.00 AAC Comparative Example 51 GA E 2.0 Zn 1 15 2.0 PA M 19 1.0 - - - 2.00 AAC Comparative Example 52 GA E 2.0 Zn 1 15 2.0 PA M 51 1.0 - - - 2.00 BCA Comparative Example 53 GA E 5.0 Zn 1 15 3.0 PA M 40 5.0 - - - 0.60 BCA Comparative Example. Petition 870250085418, dated 09 / 22 / 2025, pp. 64 / 78 55 / 55

[0129] Based on the above results, it was found that samples Nos. 1 to 44 of the metal sheets with surface treatment corresponding to the Examples were excellent in terms of appearance and adhesion of the electrodeposited films and in terms of corrosion resistance compared to samples Nos. 45 to 53 of the metal sheets with surface treatment corresponding to the Comparative Examples. In addition, the metal sheets with surface treatment of samples Nos. 1 to 44 could also be appropriately subjected to resistance welding.

[0130] This application is entitled to and claims the benefit of Japanese Patent Application No. 2023-67823 filed on April 18, 2023, the description of which, including the report and drawings, is incorporated herein by reference in its entirety. Industrial Applicability

[0131] The surface-treated sheet metal and the coated sheet metal according to the present invention are useful in various applications such as an automotive component.

[0132] List of Reference Signs 100 Metal sheet with surface treatment 110 Metal sheet 112 Galvanizing layer 120 Coating film 122 Binder resin 124 Doped oxide particle 126 Rust inhibitor pigment 200 Coated metal sheet 210 Chemical conversion treatment layer 212 Acid salt crystal 220 Electrodeposited film Petition 870250085418, dated 09 / 22 / 2025, pages 65 / 78

Claims

1 / 2 CLAIMS 1. Metal sheet with surface treatment, comprising: a metal sheet; and a coating film disposed on a surface of the metal sheet and having a thickness of 0.5 to 5.0 μm, characterized in that: the coating film includes a binder resin, a doped oxide particle and a rust inhibitor pigment, the content of the doped oxide particle is 5% to 20% by volume relative to the coating film, the content of the rust inhibitor pigment is 20% to 50% by volume relative to the coating film, and a value (B / A) of a ratio of an average particle diameter (B) of the doped oxide particle to an average particle diameter (A) of the rust inhibitor pigment is 0.75 to 4.

00.

2. Metal sheet with surface treatment according to claim 1, characterized in that the average particle diameter of the doped oxide particle is from 1.0 to 4.0 μm.

3. Metal sheet with surface treatment according to claim 1, characterized in that the doped oxide particle includes at least one member selected from the group consisting of a zinc oxide particle doped with Al, Ga or In; a tin oxide particle doped with P, Sb or As; an indium oxide particle doped with Sn or Ge; a titanium oxide particle coated with zinc oxide doped with Al, Ga or In; a titanium oxide particle coated with tin oxide doped with P, Sb or As; and a titanium oxide particle coated with indium oxide doped with Sn or Ge.

4. Metal sheet with surface treatment according to claim 1, characterized in that the average particle diameter of the rust inhibitor pigment is from 0.5 to 4.0 μm.

5. Metal sheet with surface treatment according to claim 1, characterized in that the rust-inhibiting pigment includes at least one member selected from the group consisting of a phosphate compound, a silicate compound, amorphous silica, and a vanadate compound.

6. Metal sheet with surface treatment according to claim 1, characterized in that the binder resin is a water-soluble or water-dispersible aqueous resin.

7. Metal sheet with surface treatment according to claim 6, characterized in that the binder resin is an epoxy resin.

8. Metal sheet with surface treatment according to claim 1, characterized in that the coating film does not include any of a non-oxide ceramic particle, an iron alloy particle, and a stainless steel particle.

9. Automotive member comprising a coated metal sheet, characterized in that the coated metal sheet includes the metal sheet with surface treatment as defined in any one of claims 1 to 8, a chemical conversion treatment layer disposed on a surface of the coating film, and an electrodeposited film disposed on a surface of the chemical conversion treatment layer. Petition 870250085418, dated 09 / 22 / 2025, pp. 67 / 78

Images