JP2024077622A - Surface-treated metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exert an antiviral effect for a long period of time while suppressing a manufacturing cost.

SOLUTION: The surface-treated metal sheet according to the present invention has a first coating layer that contains at least an organic silicate compound and is provided on at least one surface of the metal sheet, in which in the first coating layer, a quaternary ammonium salt-containing chemical structure forms a chemical bond with respect to the organic silicate compound, the quaternary ammonium salt-containing chemical structure being a chemical structure in which an atomic group R4 of the quaternary ammonium salt having the chemical structure represented by a chemical formula (1) is chemically bonded to at least one or more immobilization chemical structures represented by chemical formulae (2) to (4).

SELECTED DRAWING: Figure 1A

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a surface-treated metal sheet.

Due to the impact of the novel coronavirus (COVID-19) over the past few years, there is an increasing need to impart antiviral properties to various items, and businesses that apply antiviral agents to the surfaces of various items are thriving. Applying antiviral agents can be applied to existing structures, but there are problems with the high labor costs involved in application and the lack of durability of the agents, which necessitates regular application and high running costs.

On the other hand, there is a known technique for imparting antiviral properties to steel materials in advance, as shown in, for example, Patent Document 1 below. This technique uses a coated steel material as a base, and forms a protective layer and a photocatalyst layer in that order on top of the coated steel material.

JP 2009-131960 A JP 2017-14401 A JP 2017-137481 A

However, the visible light responsive photocatalyst compound contained in the photocatalyst layer disclosed in Patent Document 1 is preferably doped with a special element to enhance reactivity with visible light or supported with a metal promoter, and there is room for improvement in terms of cost.

When using photocatalytic compounds such as those described above, inorganic coatings are often made using inorganic compounds such as silica and zirconia to prevent the photocatalytic layer itself from being oxidized and decomposed by the photocatalytic compounds. When forming such inorganic coatings, paints using organic solvents such as alcohol are used, which results in the generation of volatile organic compounds (VOCs) during the formation process. However, due to emission regulations, volatile organic compounds must be discharged in a harmless state into the environment, and costs are required to make them harmless.

In light of the above situation, it is conceivable to use compounds other than photocatalyst compounds as substances that exhibit antiviral effects. For example, in the above Patent Documents 2 and 3, a compound having a quaternary ammonium salt is used as a compound that exhibits antibacterial properties. In addition, according to a recent report by the National Institute of Technology and Evaluation (June 29, 2020, news release), it is known that quaternary ammonium salts are effective in suppressing the new coronavirus (COVID-19). Therefore, it is conceivable to use a compound having a quaternary ammonium salt instead of a photocatalyst compound as a relatively inexpensive compound that exhibits antiviral effects.

However, as a result of extensive research by the present inventors into films containing quaternary ammonium salts, it was found that when quaternary ammonium salts are simply contained in a film, the quaternary ammonium salts are inactivated at an early stage. Therefore, it became clear that further improvements were required to achieve long-term antiviral effects using quaternary ammonium salts.

Therefore, the present invention has been made in consideration of the above problems, and the object of the present invention is to provide a surface-treated metal sheet that can exert an antiviral effect for a long period of time while suppressing manufacturing costs.

In order to solve the above problems, the present inventors have conducted intensive research and have found that the reason why the quaternary ammonium salt contained in the film is inactivated early is because the quaternary ammonium salt is not fixed in the film. If a person or object repeatedly touches or rubs the surface of the film, the quaternary ammonium salt that is not fixed in the film is easily removed from the surface of the film. In addition, if the surface of the film is wiped with a cloth moistened with a hydrophilic liquid such as water, alcohol, or a cleaning solution in order to clean the surface of the film, the hydrophilic quaternary ammonium salt that is not fixed is easily washed out. Therefore, if the quaternary ammonium salt can be fixed in the film, it is expected that the antiviral effect can be expressed for a long period of time.
The gist of the present invention, which was completed based on this concept, is as follows.

(1) A surface-treated metal plate having a first coating layer containing at least an organosilicic acid compound provided on at least one surface of a metal plate, wherein in the first coating layer, a quaternary ammonium salt-containing chemical structure, in which an atomic group R4 of a quaternary ammonium salt having a chemical structure represented by the following chemical formula (1) is chemically bonded to at least one or more immobilization chemical structures represented by the following chemical formulas (2) to (4), forms a chemical bond with the organosilicic acid compound.
In the following chemical formulas (1) to (4), the atomic groups R1, R2, R3, R4, R11, and R12 are each independently as follows:
R1: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R2: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R3: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R4: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R11: Has a structure represented by -C(R5)(R6)-, where R5 and R6 are each independently a hydrogen atom or a chain hydrocarbon substituent having 1 to 3 carbon atoms.
R12: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R13: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R14: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
(2) The surface-treated metal sheet according to (1), in which R1, R2, and R3 in the chemical structure do not have a chemical structure represented by the following chemical formula (5).
In the following chemical formula (5), the atomic groups X1, X2, Ar, and R are each independently as follows:
X1 and X2 each independently represent a hydrogen atom, a chain aliphatic hydrocarbon group having 1 to 3 carbon atoms, or a halogen element, and the chain aliphatic hydrocarbon group may have a hetero element. Here, n is 0, 1, or 2.
Ar: a substituted or unsubstituted aryl group; R: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.

-(C(X1)(X2)) _n -Ar-R...chemical formula (5)

(3) The surface-treated metal sheet according to (1) or (2), wherein the content of the quaternary ammonium salt in the first coating layer is 0.2 mmol or more and 3.0 mmol or less per 1 g of the first coating layer.
(4) The surface-treated metal sheet according to (3), wherein in the first coating layer, a molar ratio of the quaternary ammonium salt to at least one of the chemical structures represented by chemical formulas (2) to (4) is 1.01 to 2.00.
(5) The surface-treated metal sheet according to (1) or (2), wherein the first coating layer further contains an inorganic component having one or more elements selected from the group consisting of P, V, and Mg.
(6) The surface-treated metal sheet according to (1) or (2), wherein the first coating layer further contains a resin, and the resin is at least one selected from the group consisting of an acrylic resin, a urethane resin, and a polyester resin.
(7) The surface-treated metal sheet according to (1) or (2), wherein the average thickness of the first coating layer is 0.02 to 3.00 μm.
(8) The surface-treated metal sheet according to (1) or (2), in which a hairline is present on the surface of the metal sheet along the rolling direction of the metal sheet.
(9) The surface-treated metal sheet according to (1) or (2), wherein a spangle pattern is present on the surface of the metal sheet.
(10) The surface-treated metal sheet according to (1) or (2), further comprising a second coating layer between the first coating layer and the metal sheet.
(11) The surface-treated metal sheet according to (1) or (2), wherein the metal sheet is a zinc-based plated steel sheet.
(12) A surface-treated steel sheet according to (1) or (2), in which, when a surface-treated metal sheet having the first coating layer is immersed in boiling water for 30 minutes and then analyzed by pyrolysis gas chromatography/mass spectrometry, a total of 3 mg/g or more of either or both of N,N-dimethylethylamine or chloromethane compounds, and trimethylamine are detected in terms of a mass ratio relative to the first coating layer.

As explained above, the present invention makes it possible to exert an antiviral effect over a long period of time while keeping manufacturing costs down.

1 is a schematic diagram showing an example of a configuration of a surface-treated metal sheet according to an embodiment of the present invention. FIG. FIG. 2 is a schematic diagram showing an example of the configuration of a surface-treated metal sheet according to the embodiment. FIG. 4 is a schematic diagram showing another example of the configuration of the surface-treated metal sheet according to the embodiment. FIG. 4 is a schematic diagram showing another example of the configuration of the surface-treated metal sheet according to the embodiment.

The preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals to avoid redundant description.

(About surface-treated metal sheets)
<Structure of surface-treated metal sheet>
Hereinafter, the structure of a surface-treated metal sheet according to an embodiment of the present invention will be described with reference to Fig. 1A and Fig. 1B. Fig. 1A and Fig. 1B are explanatory diagrams that show an example of the structure of a surface-treated metal sheet according to the present embodiment.

As shown in FIG. 1A, the surface-treated metal sheet 1 according to this embodiment has at least a metal sheet 10 as a base material and a first coating layer 20.

[Regarding the metal plate 10]
In the surface-treated metal sheet 1 according to the present embodiment, various metal sheets can be used as the base metal, that is, the metal sheet 10. Examples of such metal sheets include iron, iron-based alloys, aluminum, aluminum-based alloys, copper, copper-based alloys, etc. Also, as the metal sheet 10, it is possible to use a plated metal sheet in which various metal sheets are plated.

Among them, it is preferable to use a zinc-based plated steel sheet as the metal sheet 10 according to the present embodiment. Examples of zinc-based plated steel sheets include zinc-based plated steel sheets, zinc-nickel plated steel sheets, zinc-iron plated steel sheets, zinc-chrome plated steel sheets, zinc-aluminum plated steel sheets, zinc-titanium plated steel sheets, zinc-magnesium plated steel sheets, zinc-manganese plated steel sheets, zinc-aluminum-magnesium plated steel sheets, and zinc-aluminum-magnesium-silicon plated steel sheets. In addition, as the zinc-based plated steel sheet, a sheet containing a small amount of different metal elements or impurities such as cobalt, molybdenum, tungsten, nickel, titanium, chromium, aluminum, manganese, iron, magnesium, lead, bismuth, antimony, tin, copper, cadmium, arsenic, etc. in the above plating, or a sheet having inorganic substances such as silica, alumina, and titania dispersed therein may be used. In addition, as the zinc-based plated steel sheet, a steel sheet having a multi-layer plating that combines the above plating with other types of plating (for example, iron plating, iron-phosphorus plating, nickel plating, cobalt plating, etc.) may be used. The plating method is not particularly limited, and any of the various known plating methods may be used, such as electroplating, hot-dip plating, vapor deposition plating, dispersion plating, vacuum plating, etc.

In addition, in the metal plate 10 according to this embodiment, a hairline extending along the rolling direction of the metal plate may be formed on the surface of the metal plate 10, and a spangle pattern may be present. Such hairlines, spangle patterns, etc. improve the design of the surface-treated metal plate 1 according to this embodiment, and are preferable because the surface-treated metal plate 1 according to this embodiment can also be used as an exterior component. There are no particular limitations on the method for forming such a pattern, and various known processing methods can be used as appropriate.

In particular, the hairline pattern increases the surface area of the metal plate 10 because it is a pattern that is realized by forming irregularities on the surface of the metal plate 10 (or the surface of the plating layer if the metal plate 10 has various plating layers). Therefore, even if a first coating layer 20 as described below is provided on the surface of such a metal plate 10, the first coating layer 20 is formed in a state that reflects the formed irregularities, so the surface area of the first coating layer 20 increases compared to when the hairline pattern is not provided. In this way, the hairline pattern is more preferable from the standpoint of not only design but also antiviral properties.

Here, the thickness of the metal plate 10 as described above is not particularly limited, and may be set appropriately depending on the mechanical strength (e.g., tensile strength, etc.) and processability required for the surface-treated metal plate 1 according to this embodiment.

[Regarding the first coating layer 20]
The first coating layer 20 according to this embodiment is a layer located on the outermost surface of one side of the metal plate 10, as shown in FIG. 1A, and contains at least an organosilicic acid compound having a specific chemical structure that exhibits antiviral properties, as described in detail below.

<Chemical structure containing quaternary ammonium salt>
More specifically, in the first coating layer 20, a quaternary ammonium salt-containing chemical structure, which is a chemical structure in which an atomic group R4 of a quaternary ammonium salt having a chemical structure represented by the following chemical formula (1) is chemically bonded to at least one or more immobilization chemical structures represented by the following chemical formulas (2) to (4), forms a chemical bond to the organosilicic acid compound.

In the above chemical formulas (1) to (4), the atomic groups R1, R2, R3, R4, R11, and R12 are each independently as follows:

R1: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R2: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R3: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R4: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R11: Has a structure represented by -C(R5)(R6)-, where R5 and R6 are each independently a hydrogen atom or a chain hydrocarbon substituent having 1 to 3 carbon atoms.
R12: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R13: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R14: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.

Of the above chemical structures, the chemical structure represented by chemical formula (1) is a chemical structure containing a quaternary ammonium salt, and when contained in the first coating layer 20, it exhibits antiviral and antibacterial properties. As shown in the above chemical formula (1), the quaternary ammonium salt has a positive charge. Due to this positive charge, the quaternary ammonium salt adsorbs to the envelope of the virus, which has a negative charge, causing the envelope to flow and collapse. This collapse of the envelope inactivates the virus adsorbed by the quaternary ammonium salt.

Among the above chemical structures, the chemical structures represented by chemical formulas (2) to (4) are chemical structures for immobilizing the quaternary ammonium salt represented by chemical formula (1) to the organosilicate compound contained in the first coating layer 20. The quaternary ammonium salt having the chemical structure represented by chemical formula (1) and the immobilization chemical structures represented by chemical formulas (2) to (4) are chemically bonded to each other at the position represented by R4 to form a quaternary ammonium salt-containing chemical structure.

Here, in the case of the chemical structure represented by chemical formula (2), the chemical structure is chemically bonded to an organic silicic acid compound at the bond of the atomic group R12 or at the position of the oxygen atom bonded to the carbon atom located between the atomic groups R11 and R12. In addition, in the case of the chemical structure represented by chemical formula (3), the chemical structure is chemically bonded to an organic silicic acid compound at the bond of the oxygen atom chemically bonded to the silicon atom or at the bond of the atomic group R14. In addition, in the case of the chemical structure represented by chemical formula (4), the chemical structure is chemically bonded to an organic silicic acid compound at the bond of the atomic group R13.

In this manner, in the first coating layer 20 of this embodiment, in addition to the quaternary ammonium salt, the first coating layer 20 contains a chemical structure capable of bonding with an organic silicic acid compound (i.e., the chemical structures represented by chemical formulas (2) to (4)). This makes it possible to fix the quaternary ammonium salt to the organic silicic acid compound and maintain the antiviral activity of the quaternary ammonium salt for a long period of time.

In addition, the above-mentioned quaternary ammonium salt-containing chemical structure is a polar chemical structure, and therefore is soluble in aqueous solvents. This makes it possible to suppress the generation of volatile organic compounds when forming the first coating layer 20.

Here, the number of carbon atoms in the atomic groups R1, R2, and R3 is preferably 1 to 3, each independently. The number of carbon atoms in the atomic group R4 is preferably 1 to 6. The number of carbon atoms in the atomic groups R5 and R6 is preferably 0 to 1, each independently. The number of carbon atoms in the atomic groups R12, R13, and R14 is preferably 1 to 6, each independently.

In addition, since quaternary ammonium salts inactivate viruses by adsorbing to the negatively charged virus envelope, it is preferable that the charge of the quaternary ammonium salt is as large a positive value as possible. From this perspective, it is preferable that, among the carbon atoms constituting the atomic groups R1, R2, and R3 bonded to the central N atom, no electron-donating atomic groups are bonded to the first and second carbon atoms counting from the N atom (i.e., the carbons at the α and β positions).

More specifically, it is preferable that the atomic groups R1, R2, and R3 in the above chemical structure do not have a chemical structure represented by the following chemical formula (5).

-(C(X1)(X2)) _n -Ar-R...chemical formula (5)

In the above chemical formula (5), the atomic groups X1, X2, Ar, and R are each independently as follows:

X1 and X2 each independently represent a hydrogen atom, a chain aliphatic hydrocarbon group having 1 to 3 carbon atoms, or a halogen element, and the chain aliphatic hydrocarbon group may have a hetero element. Here, n is 0, 1, or 2.
Ar: a substituted or unsubstituted aryl group; R: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.

In the above chemical formula (5), the aryl group, such as the naphthyl group or the phenyl group, and the benzyl group are electron-donating atomic groups, and therefore act to weaken the positive charge of the quaternary ammonium salt.

Here, examples of quaternary ammonium salts having the chemical structure represented by the above chemical formula (1) include quaternary ammonium salts represented by the following chemical formulas (11) to (13). The compound represented by chemical formula (11) is trimethylammonium acetate, the compound represented by chemical formula (12) is trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, and the compound represented by chemical formula (13) is glycidyltrimethylammonium chloride.

A specific example of a quaternary ammonium salt-containing chemical structure in which the chemical structure represented by the above chemical formula (1) and the immobilization chemical structure represented by the chemical formula (2) are chemically bonded to each other via R4 is the chemical structure represented by the following chemical formula (21): In the chemical structure represented by the following chemical formula (21), the atomic group R12 is, for example, an atomic group represented by _-CH2O ( _CH2 ) ₃ .

A specific example of a quaternary ammonium salt-containing chemical structure in which the chemical structure represented by the above chemical formula (1) and the immobilization chemical structure represented by the chemical formula (3) are chemically bonded to each other via R4 is the chemical structure represented by the following chemical formula (31). Here, in the chemical structure represented by the following chemical formula (31), the atomic group R14 is, for example, an atomic group represented by -( _CH2 ) ₃ .

A specific example of a quaternary ammonium salt-containing chemical structure in which the chemical structure represented by the above chemical formula (1) and the immobilization chemical structure represented by the chemical formula (4) are chemically bonded to each other via R4 is the chemical structure represented by the following chemical formula (41): In the chemical structure represented by the following chemical formula (41), the atomic group R13 is, for example, an atomic group represented by -( _CH2 ) ₃ .

As the quaternary ammonium salt-containing chemical structure according to this embodiment, for example, a chemical structure represented by chemical formula (21), a chemical structure represented by chemical formula (31), a chemical structure represented by chemical formula (41), or the like can be suitably used.

In addition, whether or not the quaternary ammonium salt represented by the above chemical formula (1) is immobilized in the first coating layer 20 according to this embodiment can be confirmed by a color test using a reagent that undergoes a color reaction with the quaternary ammonium salt. More specifically, the color test can be carried out as follows.

Because the first coating layer of interest may contain unimmobilized quaternary ammonium salt, the metal plate on which the first coating layer is formed on the outermost surface is immersed in boiling water for 30 minutes to thoroughly dissolve and remove the unimmobilized quaternary ammonium salt from the coating. After that, several drops of an aqueous solution of a reagent that reacts with the quaternary ammonium salt (dye solution) are dropped onto the coating, and after about 20 minutes, the presence or absence of discoloration of the dye solution is checked. As the dye solution, a diluted reagent containing an anionic dye can be used without adjusting the pH. For example, as the dye solution, a saturated aqueous solution of a reagent such as bromothymol blue, bromophenol blue, or methyl orange is diluted 10 times with water, and used in its diluted state without adjusting the pH with a pH standard solution or the like.

If the compound that makes up the film contains quaternary ammonium salt sites, the bromothymol blue solution, which is yellow-green when dropped onto the film, will gradually change color to blue-green in about 20 minutes. Also, the maroon bromophenol blue solution will change color to a deep blue over time, and the orange methyl orange solution will change color to yellow over time. The reason these reagents change color when they come into contact with the quaternary ammonium salt sites in the film is because the molecules of the reagent, which are anionic dyes, form ion associates with the quaternary ammonium salt sites that contain nitrogen cations, changing the wavelength of visible light absorbed.

In addition, whether or not the quaternary ammonium salt represented by the above chemical formula (1) is chemically bonded to the chemical structures represented by chemical formulas (2) to (4) can be confirmed by pyrolysis-gas chromatography/mass spectrometry (p-GC/MS). More specifically, the analysis can be carried out according to the following procedure.

(1) Pretreatment: Since the first coating layer of interest may contain unimmobilized quaternary ammonium salt, the surface-treated metal sheet having the first coating layer 20 is immersed in boiling water for 30 minutes to thoroughly dissolve the unimmobilized quaternary ammonium salt and remove it from the coating.

(2) Thermal decomposition of the quaternary ammonium salt site fixed in the film: The surface-treated metal plate that has been treated in the above step (1) is placed in an inert gas such as nitrogen heated to 250-260°C. This causes instantaneous thermal decomposition. If the quaternary ammonium salt represented by chemical formula (1) is chemically bonded to the chemical structures represented by chemical formulas (2) to (4), at least one of the four types of tertiary amines, namely (a) N(-R1)(-R2)(-R3), (b) N(-R1)(-R2)(-R4-chemical structure for fixing-organic silicic acid compound), (c) N(-R1)(-R3)(-R4-chemical structure for fixing-organic silicic acid compound), and (d) N(-R2)(-R3)(-R4-chemical structure for fixing-organic silicic acid compound) is generated.

(3) Analysis by p-GC/MS: Trimethylamine is detected from the first coating layer according to this embodiment. Trimethylamine is generated by thermal decomposition of the quaternary ammonium salt in the first coating layer. In addition, either N,N-dimethylethylamine or chloromethane or both are detected. Chloromethane is generated by thermal decomposition of the quaternary ammonium salt and reaction with the chloride ions contained in the quaternary ammonium salt. In addition, when a compound in which a carboxyl group is bonded to a quaternary ammonium salt, such as the compound (11) above, is heated, carbon dioxide is eliminated to generate an ylide compound. The ylide compound is further heated to generate N,N-dimethylethylamine. In this way, by confirming whether or not the total of either N,N-dimethylethylamine or either chloromethane or both compounds and trimethylamine is detected in a mass ratio of 3 mg/g or more relative to the first coating layer by this analysis method, it is possible to determine whether or not the coating layer of interest is the first coating layer according to this embodiment.

Next, the above analysis method will be described in detail below.
For example, the p-GC/MS can be a combination of a GCMS-QP2010 model (manufactured by Shimadzu Corporation) as the main body and a pyrolyzer JCI-55 (manufactured by Japan Analytical Industry Co., Ltd.) and a BD-1 (manufactured by GL Sciences Co., Ltd.: inner diameter 0.25 mm, length 30 m) can be used as the column.

First, a sample of the first coating layer to be used for analysis is taken from the surface-treated metal plate of interest. There is no particular limitation on the method of taking the first coating layer from the surface-treated metal plate. A simple method is to mechanically scrape it off. The taken sample is pretreated as described in (1) above, and the mass of the sample after pretreatment is measured in advance. The pyrolysis of the first coating layer as described in (2) above is performed by wrapping the obtained sample in pyrofilm, further wrapping the sample in foil in a helium gas atmosphere, and irradiating the foil wrapped in the helium gas atmosphere with high frequency waves. The gas generated by instantaneous heating due to such pyrolysis is introduced into the p-GC/MS. The pyrolysis temperature is preferably about 250 to 260°C. The pyrolysis time is preferably about 5 seconds.

The column temperature in the p-GC/MS should be held at 40°C for 5 minutes before gas introduction. This will suppress the progression of desorption from the column due to heat, and facilitate separation due to affinity with the column. In particular, it will be possible to detect substances that desorb from the column at low temperatures and have a short column retention time (e.g., triethylamine and chloromethane). The column temperature should be held at 40°C for 5 minutes, then heated to 150°C at a heating rate of 10°C/min, and further heated to 280°C at a heating rate of 20°C/min, and held at 280°C for 1.5 minutes. The gas introduction temperature and ion source temperature are preferably set to 210°C, and the mass range m/z is preferably set to 35 to 500.

In addition, standard substances for N,N-dimethylethylamine, chloromethane, and trimethylamine are prepared, and analysis is performed by p-GC/MS in the same manner as above. This makes it possible to perform quantitative analysis of N,N-dimethylethylamine, chloromethane, and trimethylamine in the surface-treated metal sheet of interest based on the analysis results obtained in (3) above.

Here, in the first coating layer 20 according to this embodiment, as described above, the quaternary ammonium salt is fixed to the coating, but the first coating layer 20 according to this embodiment may have unfixed quaternary ammonium salt in addition to the fixed quaternary ammonium salt.

The content of the quaternary ammonium salt contained in the first coating layer 20 according to this embodiment (more specifically, the total content of the immobilized quaternary ammonium salt and the unimmobilized free quaternary ammonium salt in the first coating layer 20) is preferably 0.2 mmol or more per 1 g of the first coating layer. By making the total content of the quaternary ammonium salt 0.2 mmol or more per 1 g of the first coating layer, it is possible to maintain the antiviral activity expressed by the quaternary ammonium salt for a longer period of time. The total content of the quaternary ammonium salt is more preferably 0.3 mmol or more, and even more preferably 0.5 mmol or more.

In addition, in the first coating layer 20 according to this embodiment, the total content of the immobilized quaternary ammonium salt and the unimmobilized free quaternary ammonium salt is preferably 3.0 mmol or less per 1 g of the first coating layer. If the total content of the quaternary ammonium salt is too high, moisture is easily drawn into the coating, which may affect the corrosion resistance of the metal plate 10 depending on the type of metal plate 10. By setting the total content of the quaternary ammonium salt per 1 g of the first coating layer to 3.0 mmol or less, it is possible to maintain the antiviral activity expressed by the quaternary ammonium salt for a longer period of time without affecting the corrosion resistance of the metal plate 10. The total content of the quaternary ammonium salt is more preferably 2.0 mmol or less, and even more preferably 1.6 mmol or less.

Here, in order to measure the total content of the immobilized quaternary ammonium salt and the unimmobilized free quaternary ammonium salt in the already formed first coating layer 20, the number of moles of quaternary ammonium salt contained in 1 g of the first coating layer before immersion in boiling water can be determined using a method using an ion pair reagent (sodium alkanesulfonate) described below.

In addition, in the first coating layer 20 according to this embodiment, the molar ratio (=total number of moles of chemical formula (1)/number of moles of chemical formulas (2) to (4) combined with chemical formula (1)) between the total number of moles of the quaternary ammonium salt (the sum of the number of moles of immobilized quaternary ammonium salt and the number of moles of free quaternary ammonium salt) and the total number of moles of at least one or more chemical structures in which the quaternary ammonium salt contained in the first coating layer 20 is immobilized, is preferably within the range of 1.01 to 2.00. By setting the molar ratio within the above range, it is possible to reduce the proportion of quaternary ammonium salt that is not immobilized in the first coating layer 20, and it is possible to maintain antiviral activity for a longer period of time without excessively increasing manufacturing costs. The molar ratio is more preferably 1.05 to 1.60.

Here, in order to measure the above molar ratio after the fact in the first coating layer 20 that has already been formed, an ion pair reagent (sodium alkane sulfonate) that forms an ion pair with the central atom N ⁺ of the quaternary ammonium salt site may be used, and the measurement may be carried out according to the following procedures (1) to (6).

(1) Preparation of sodium alkanesulfonate solution: (A) sodium 1-heptanesulfonate ( _CH3 ( _CH2 ) ₆ - _SO3Na ) of known molar concentrations, (B) sodium 1-decanesulfonate ( _CH3 ( _CH2 ) ₉ - _SO3Na ) of known molar concentrations, (C) sodium 1-dodecanesulfonate ( _CH3 ( _CH2 ) ₁₁ - _SO3Na ) of known molar concentrations, and (D) sodium 1-pentadecanesulfonate ( _CH3 ( _CH2 ) ₁₄ - _SO3Na ) of known molar concentrations are each dissolved in a 1/1 (w/w) mixed solvent of methanol/water, and the pH of the solution is adjusted to about 3.5 with 85% phosphoric acid.

(2) Extraction of unimmobilized quaternary ammonium salt: An extraction operation is performed on the first coating layer of interest. The surface-treated metal sheet 1 having the first coating layer 20 is immersed in boiling water for 30 minutes to thoroughly dissolve the water-soluble components, and an eluate and an extraction residue coating are obtained. The eluate may contain quaternary ammonium salt that is not immobilized in the coating, and the extraction residue coating contains quaternary ammonium salt that is immobilized in at least one chemical structure represented by chemical formulas (2) to (4).

(3) Preparation of a test specimen a for ion chromatography from the eluate: The eluate obtained in (2) above is added to the solution of sodium alkane sulfonate (A) obtained in (1) above, stirred and mixed to form an ion pair of quaternary ammonium salt and sodium alkane sulfonate in a molar ratio of 1:1. When a quaternary ammonium cation and an alkane sulfonate anion form an ion pair, the charges are cancelled out, increasing hydrophobicity, and a precipitation may occur. If a precipitation occurs when using solution (A), the mixture containing the precipitation is filtered to remove the precipitation, and the filtrate is used as the test specimen a for ion chromatography. The test specimen a contains sodium alkane sulfonate that was not consumed in the formation of an ion pair with the unimmobilized quaternary ammonium salt. If no precipitation occurs when using solution (A) in the above mixing operation, the same mixing operation as above is performed using solution (B), and if a precipitation occurs, the precipitation is removed by filtration, and the filtrate is used as the test specimen a for ion chromatography. If no precipitation occurs when solution (B) is used, the same mixing operation as above is performed using solution (C), and if a precipitation occurs, the filtrate is used as the test specimen a for ion chromatography. If no precipitation occurs when solution (C) is used, the same mixing operation as above is performed using solution (D), the precipitation is removed by filtration, and the filtrate is used as the test specimen a for ion chromatography.

(4) Formation of test specimen b for ion chromatography from the extraction residue film: The solution of sodium alkane sulfonate precipitated in (3) above is prepared again according to (1) above. The extraction residue film obtained in (2) above is scraped off the metal plate, crushed, and added to the sodium alkane sulfonate solution prepared again, followed by stirring and mixing. After forming an ion pair between sodium alkane sulfonate and the quaternary ammonium salt immobilized in at least one chemical structure represented by chemical formulas (2) to (4) contained in the extraction residue film, the mixture is filtered to remove the film pieces, and the filtrate is used as test specimen b for ion chromatography. Test specimen b contains sodium alkane sulfonate that was not consumed in the formation of an ion pair with the immobilized quaternary ammonium salt.

(5) Ion chromatographic analysis of each specimen: The sodium alkane sulfonate solution used to prepare specimens a and b in (3) and (4) above is prepared again according to (1) above to prepare specimen c. Here, the molar concentrations of sodium alkane sulfonate contained in specimens a, b, and c are ma, mb, and mc, respectively, and the volumes of specimens a, b, and c are Va, Vb, and Vc, respectively. As described in (1) above, mc is known, but ma and mb are unknown. Va, Vb, and Vc are known. Ion chromatographic analysis is performed on specimens a, b, and c, and it is confirmed that the peaks of alkane sulfonate anions appear at the same retention time in the chromatograms of each specimen. Since the peak area ratio of the alkane sulfonate anion of test specimen a and test specimen c corresponds to the ratio ma/mc, ma is calculated by ma = mc x peak area ratio. Similarly, mb is calculated from the peak area ratio of the alkane sulfonate anion of test specimens b and c and mc.

(6) Calculation of the molar ratio between the quaternary ammonium salt represented by chemical formula (1) and at least one or more chemical structures represented by chemical formulas (2) to (4) bound to the quaternary ammonium salt: The number of moles of sodium alkane sulfonate contained in the test specimens a, b, and c used in the analysis in (5) above is ma x Va, mb x Vb, and mc x Vc, respectively. Therefore, the number of moles of sodium alkane sulfonate consumed in forming an ion pair with the non-immobilized quaternary ammonium salt is [mc x Vc - ma x Va]. In addition, the number of moles of sodium alkane sulfonate consumed in forming an ion pair with the quaternary ammonium salt bound to at least one or more chemical structures represented by chemical formulas (2) to (4) and bound to the immobilized quaternary ammonium salt is [mc x Vc - mb x Vb]. From these, the molar ratio of the quaternary ammonium salt represented by chemical formula (1) contained in the first coating layer of interest to at least one or more chemical structures represented by chemical formulas (2) to (4) bonded to the quaternary ammonium salt can be calculated as {[mc x Vc - ma x Va] + [mc x Vc - mb x Vb]} / [mc x Vc - mb x Vb].

<Organic silicate compounds>
When the organosilicic acid compound contained in the first coating layer 20 according to this embodiment has a fixing chemical structure represented by chemical formula (2), such an organosilicic acid compound can be obtained by chemically bonding silane coupling agents having one or more epoxy groups together, or by allowing a silane coupling agent having one or more epoxy groups to coexist with another silane coupling agent and chemically bonding them. Examples of silane coupling agents having one or more epoxy groups include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane. Examples of other silane coupling agents that can be used together with the silane coupling agent having one or more epoxy groups include 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyl Triethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropyltrimethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropyltriethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropylmethyldiethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane , 3-mercaptopropylmethyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, vinyltriacetoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltriethoxysilane, 3-chloropropylmethyldiethoxysilane, 3-anilinopropyltrimethoxysilane, 3-anilinopropylmethyldimethoxysilane, 3-anilinopropyltriethoxysilane, 3-anilinopropylmethyldiethoxysilane, vinyltrimethoxysilane , vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldimethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(triethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldiethoxysilyl)propyl]ammonium chloride, 3-chloropropylmethyldimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and the like.

When the organosilicic acid compound contained in the first coating layer 20 according to this embodiment has a fixing chemical structure represented by chemical formula (4), such an organosilicic acid compound can be obtained by chemically bonding silane coupling agents having one or more amino groups (-NH ₂ ) together, or by allowing a silane coupling agent having one or more amino groups to coexist with another silane coupling agent and chemically bonding them. Examples of silane coupling agents having one or more amino groups include 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and the like. Examples of other silane coupling agents that can be used together with the silane coupling agent having one or more amino groups include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and silanes having a secondary amino group (-NHR, R is an alkyl group) but not an amino group -NH N-2-(N-vinylbenzylaminoethyl)-3-aminopropyltrimethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropyltriethoxysilane, N-2-(N-vinylbenzylaminoethyl)-3-aminopropylmethyldiethoxysilane, and ₃ -mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, vinyltriacetoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltriethoxysilane, 3-chloropropylmethyldiethoxysilane, 3-anilinopropyltrimethoxysilane, Anilinopropylmethyldimethoxysilane, 3-anilinopropyltriethoxysilane, 3-anilinopropylmethyldiethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldimethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(triethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(methyldiethoxysilyl)propyl]ammonium chloride, 3-chloropropylmethyldimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and the like can be mentioned.

When the organosilicate compound contained in the first coating layer 20 according to this embodiment has a chemical structure for immobilization represented by chemical formula (3), the silane coupling agent for forming such organosilicate compound is not particularly limited as long as it dissolves in the aqueous surface treatment agent used to form the first coating layer 20 according to this embodiment, and various silane coupling agents can be used.

The amount of the silane coupling agent added in the surface treatment agent for forming the first coating layer 20 can be, for example, 2 to 80 g/L. By adding 2 g/L or more of the silane coupling agent, it is possible to improve the adhesion to the metal plate surface and improve the processing adhesion of the coating film. In addition, by adding 80 g/L or less of the silane coupling agent, it is possible to maintain the cohesive force of the coating film and improve the processing adhesion of the coating film. The silane coupling agents exemplified above may be used alone or in combination of two or more. When one type is used, the alkoxysilyl groups of the silane coupling agent mainly bond to each other through hydrolysis and dehydration condensation reactions to form an organic silicic acid compound. When two or more types are used in combination, the alkoxysilyl groups of the same silane coupling agent or different silane coupling agents, and further, different reactive organic functional groups of different silane coupling agents (for example, amino groups and epoxy groups) bond to each other to form an organic silicic acid compound.

In addition, as the organic silicate compound contained in the first coating layer 20 according to this embodiment, it is also possible to use an organic silicate compound obtained by mixing and reacting a silane coupling agent containing one amino group in the molecule and a silane coupling agent containing one epoxy group in the molecule in a predetermined mixing ratio, as disclosed in, for example, Japanese Patent No. 4776458.

<Inorganic components>
Furthermore, the first coating layer 20 according to this embodiment may further contain, in addition to the above components, an inorganic component having one or more elements selected from the group consisting of P, V, and Mg.

The first coating layer 20 contains inorganic components having the elements described above, which improves the film-forming properties of the film, the barrier properties (density) of the film against corrosive factors such as moisture and corrosive ions, and the adhesion of the film to the metal plate surface, thereby contributing to improving the corrosion resistance of the film.

Here, examples of inorganic components containing P include phosphoric acids such as phosphoric acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, and their salts, and ammonium dihydrogen phosphate. Examples of inorganic components containing V include ammonium metavanadate (V), potassium metavanadate (V), sodium metavanadate (V), vanadyl sulfate (IV), and the like. Examples of inorganic components containing Mg include magnesium nitrate, magnesium sulfate, magnesium acetate, and the like.

In the first coating layer 20 according to this embodiment, the various inorganic components as described above can be used alone or in combination. The content of the various inorganic components as described above can also be adjusted as appropriate.

<Resin>
In addition, the first coating layer 20 according to the present embodiment may further contain a known organic resin, such as a polyester resin, a polyurethane resin, an acrylic resin, etc., as a binder resin. These resins have polar sites or polar functional groups in the molecular chain, which makes it possible to further increase the adhesion to the metal plate. These resins may be used alone or in combination of two or more types.

The resin content in the first coating layer 20 is, for example, preferably 0% by mass or more, and more preferably 1% by mass or more, relative to the coating solid content. This can improve corrosion resistance. The resin content in the first coating layer 20 is, for example, preferably 85% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less, relative to the coating solid content. By setting the resin content to 85% by mass or less, the corrosion resistance of the coating can be improved while ensuring the performance required of the coating other than corrosion resistance.

<Average thickness of first coating layer 20>
The average thickness of the first coating layer 20 described above (thickness _d1 in FIG. 1A) is preferably 0.02 μm or more. If the average thickness _d1 of the first coating layer 20 is less than 0.02 μm, it is difficult to uniformly form the first coating layer 20 as described above, and the antiviral effect obtained may be uneven. By setting the average thickness _d1 to 0.02 μm or more, it is possible to uniformly exert the desired antiviral effect throughout the first coating layer 20.

On the other hand, the average thickness _d1 of the first coating layer 20 is preferably 3.00 μm or less. If the average thickness _d1 of the first coating layer 20 exceeds 3.00 μm, the antiviral effect obtained is saturated while the manufacturing cost increases, which is not preferable. By setting the average thickness _d1 to 3.00 μm or less, it is possible to uniformly exert the desired antiviral effect throughout the first coating layer 20 while suppressing an increase in manufacturing costs.

The average thickness _d1 of the first coating layer 20 is more preferably 0.05 μm or more, and even more preferably 0.10 μm or more. The average thickness _d1 of the first coating layer 20 is more preferably 2.60 μm or less, and even more preferably 2.20 μm or less.

The average thickness of the first coating layer 20 can be measured by observing the first coating layer 20 from a cross-sectional direction using a microscope. A sample to be observed from a cross-sectional direction can be prepared by known methods such as embedding the sample in resin and polishing the observation surface, FIB processing, or microtome method. As for the type of microscope, known devices such as SEM and TEM can be used.

The first coating layer 20 according to this embodiment has been described in detail above.
The first coating layer 20 according to this embodiment may be provided on both surfaces of the metal plate 10, as shown in FIG. 1B.

(Modification)
In addition, the surface-treated metal sheet 1A according to a modified example of this embodiment may further have a second coating layer 30 between the metal sheet 10 and the first coating layer 20, as shown in Figures 2A and 2B.

As such a second coating layer 30, for example, a colored coating layer containing various known color pigments can be mentioned. This makes it possible to give the appearance of the surface-treated metal sheet 1A according to this embodiment a desired color tone, and further improves the design of the surface-treated metal sheet 1A.

Here, the type and content of the color pigment contained in the second coating layer 30 are not particularly specified and may be adjusted as appropriate.

The surface-treated metal sheet according to this embodiment has been described in detail above with reference to Figures 1A to 2B.

(Method of manufacturing surface-treated metal sheet)
The surface-treated metal plate according to this embodiment as described above can be manufactured by subjecting the surface of the base metal plate 10 to various pretreatments, such as cleaning, as necessary, and then applying a surface treatment agent for forming the second coating layer 30 and a water-based surface treatment agent for forming the first coating layer 20, followed by drying and baking.

Here, the method of applying the surface treatment agent to form the second coating layer 30 is not particularly limited, and can be any generally known application method, such as roll coating, curtain flow coating, air spray, airless spray, immersion, bar coating, brush coating, etc. In particular, roll coating is preferred because it can be applied stably to form a thin film, which is a characteristic of this product.

On the other hand, the preparation and application of the aqueous surface treatment agent for forming the first coating layer 20 and the formation of the first coating layer 20 are carried out in the following steps [1] to [3].

[1] Preparation of organosilicic acid compound oligomers dissolved in a water-based surface treatment agent (1A) Addition of a silane coupling agent to a solvent: Pure water is used as a solvent, and the pH of the solvent is kept near neutral (for example, within the range of pH: 5.0 to 9.0). For adjusting the pH of the solvent, a low molecular weight volatile organic acid (for example, formic acid or acetic acid) is used as necessary. While stirring the solvent with a stirrer, a silane coupling agent is added to form an organosilicic acid compound having at least one chemical structure among chemical formulas (2) to (4). When the organosilicic acid compound to be formed has a chemical structure for immobilization represented by chemical formula (2), a silane coupling agent having one or more epoxy groups is required, as described in the above section on organosilicic acid compounds. When the organosilicic acid compound to be formed has a chemical structure for immobilization represented by chemical formula (4), a silane coupling agent having one or more amino groups (-NH ₂ ) is required. On the other hand, when the organic silicic acid compound to be formed has a chemical structure for immobilization represented by chemical formula (3), the silane coupling agent to be used is not particularly limited as long as it dissolves in the aqueous surface treatment agent used to form the first coating layer 20 according to this embodiment, and various silane coupling agents can be used. When two or more types of silane coupling agents are used in combination, gels or precipitation may occur due to a rapid association reaction between different silane coupling agents, so the second and subsequent types of silane coupling agents are added gradually in small amounts.

(1B) Bonding of organic groups of silane coupling agents: When two or more different silane coupling agents are used in combination, they are reacted under conditions in which the different reactive organic functional groups of the silane coupling agents react with each other. For example, the reaction temperature and reaction time are set to suit the type and combination of the silane coupling agents, and a catalyst for promoting the reaction is added as necessary. The reactive organic groups of the silane coupling agents are bonded to each other while stirring with a stirrer or the like. If the reaction temperature is too low or the reaction time is too short, the bonding reaction between the reactive organic groups does not proceed, and the desired oligomer of the organic silicate compound cannot be obtained. If the reaction temperature is too high or the reaction time is too long, the molecular weight of the polymer formed by the bonding between the reactive organic groups becomes too high and cannot be dissolved in the aqueous surface treatment agent, resulting in precipitation or gelation, so it is necessary to set an appropriate reaction temperature and reaction time. Note that when preparing the treatment agent using one type of silane coupling agent, the operation in this section (1B) is not necessary.

(1C) Bonding between alkoxysilyl groups of silane coupling agents: When preparing a treatment agent using one type of silane coupling agent, carry out the operation of this section (1C) after the above (1A). When preparing a treatment agent using two or more different silane coupling agents in combination, carry out the operation of this section (1C) after the above (1B). The pH of the aqueous surface treatment agent is adjusted to acidic (for example, pH: within the range of 2.0 to 4.5) with a low molecular weight volatile organic acid, etc., and the reaction temperature and reaction time determined by the carbon number of the alkoxysilyl group contained in the aqueous surface treatment agent are set, and the alkoxysilyl group is hydrolyzed while stirring with a stirrer or the like (the hydrolysis rate tends to be slower as the carbon number of the alkoxysilyl group increases). After a predetermined reaction time, the pH of the aqueous surface treatment agent is adjusted to near neutral (for example, pH: within the range of 5.0 to 6.5) with a low molecular weight volatile base (for example, ammonia water, etc.). As the pH rises, the condensation reaction of the hydrolyzed alkoxysilyl groups accelerates, and the hydrolyzed alkoxysilyl groups bond together to produce oligomers of the organic silicic acid compound. If the reaction temperature is too low or the reaction time is too short, the reaction between the hydrolyzed alkoxysilyl groups does not proceed, and the desired oligomer of the organic silicic acid compound cannot be obtained. If the reaction temperature is too high or the reaction time is too long, the molecular weight of the polymer formed by the bond between the hydrolyzed alkoxysilyl groups becomes too high and it cannot be dissolved in the aqueous surface treatment agent, resulting in precipitation or gelation, so it is necessary to set an appropriate reaction temperature and reaction time.

[2] Preparation of aqueous surface treatment agent containing quaternary ammonium salt Addition of quaternary ammonium salt to aqueous surface treatment agent obtained in [1] above: The oligomer of organic silicic acid compound obtained in [1] above contains at least a trace amount of unreacted reactive organic functional groups (e.g., unreacted amino groups, epoxy groups, etc.) derived from the silane coupling agent used in [1] (1A).Therefore, a quaternary ammonium salt having a reactive organic functional group that can be bonded to the unreacted reactive organic functional group is added to the aqueous surface treatment agent obtained in [1] above, and the mixture is thoroughly mixed by stirring with a stirrer or the like.

For example, if the silane coupling agent used in [1] (1A) contains an epoxy group, the oligomer of the organosilicic acid compound obtained in [1] contains at least a trace amount of unreacted epoxy groups, so a quaternary ammonium salt having a carboxy group (-COOH), a carboxylate group ( ^-COO- ), or an amino group that easily reacts with the epoxy group is added. When a quaternary ammonium salt having a carboxy group or a carboxylate group is used, the first coating layer 20 formed after the treatment agent is formed contains a chemical structure for immobilization represented by chemical formula (2). When a quaternary ammonium salt having an amino group is used, the first coating layer 20 formed after the treatment agent is formed contains a chemical structure for immobilization represented by chemical formula (4). If the silane coupling agent used in [1] (1A) contains an amino group, the oligomer contains at least a trace amount of unreacted amino groups, so a quaternary ammonium salt having an epoxy group that easily reacts with the amino group is added. In this case, the first coating layer 20 formed after the treatment agent is formed into a film contains the immobilizing chemical structure represented by chemical formula (4).

Regardless of the type of silane coupling agent used to form the oligomer, the oligomer contains at least a small amount of unreacted alkoxysilyl groups. Therefore, if a quaternary ammonium salt having an alkoxysilyl group is added, the alkoxysilyl groups are more likely to react with each other, and the first coating layer 20 formed after the treatment agent is formed has a chemical structure for immobilization represented by chemical formula (3).

[3] Formation of the first coating layer 20 When a quaternary ammonium salt having a reactive organic functional group other than an alkoxysilyl group is used in the preparation of the treatment agent in [2] above, as described in the above section on «organic silicic acid compounds», such a quaternary ammonium salt needs to be a quaternary ammonium salt having at least one of an epoxy group and an amino group (-NH ₂ ). The reactive organic functional group of such a quaternary ammonium salt is reacted under conditions in which it reacts with the unreacted reactive organic functional group of the oligomer of the organosilicic acid compound obtained in [1] above. When the organosilicic acid compound to be formed has a chemical structure for immobilization represented by chemical formula (2), as described in the above section on «organosilicic acid compounds», a silane coupling agent having one or more epoxy groups is needed. When the organosilicic acid compound to be formed has a chemical structure for immobilization represented by chemical formula (4), a silane coupling agent having one or more amino groups is needed.

On the other hand, when a quaternary ammonium salt having an alkoxysilyl group is used to prepare the treatment agent of [2] above, the pH of the treatment agent is adjusted to acidic (for example, pH: in the range of 2.0 to 4.5) with a low molecular weight volatile organic acid, etc., and the alkoxysilyl group of the quaternary ammonium salt added to the treatment agent is hydrolyzed while stirring with a stirrer or the like. Then, the treatment agent is applied to the metal plate 10, and the aqueous surface treatment agent on the metal plate is heated and dried under the drying and baking conditions described below, whereby at least a portion of the organic acid, etc. used to adjust the pH of the treatment agent volatilizes, and the pH immediately rises to near neutral (for example, pH: in the range of 5.0 to 6.5). As a result, the condensation reaction between the hydrolyzed alkoxysilyl groups is promoted, and a coating layer having the immobilization chemical structure represented by chemical formula (3) is formed.

In the above [1] (1C) and [3], when adjusting the pH of the aqueous surface treatment agent to an acidic value, if an acid that does not easily volatilize is used in the subsequent drying and baking process, the pH will not rise to near neutrality due to drying and baking, and the condensation reaction between the hydrolyzed alkoxysilyl groups will not proceed, and a first coating layer with the desired chemical structure will not be obtained.

In addition, for the aqueous surface treatment agent for forming the first coating layer 20 having at least one of chemical formulas (2) and (4) as the chemical structure for immobilization, but not chemical formula (3), there is no need to adjust the pH, as in the case of applying an aqueous surface treatment agent for forming the first coating layer 20 having chemical formula (3) as the chemical structure for immobilization.

There are no particular limitations on the conditions for drying and baking, and it is sufficient to ensure that the temperature conditions and holding time are such that the water solvent is sufficiently removed and at least a portion of the low molecular weight, volatile organic acid is volatilized. For example, the metal plate coated with the water-based surface treatment agent or the like as described above is held at a temperature of 60°C for about 10 seconds.

The above describes the manufacturing method for surface-treated metal sheets according to this embodiment.

Below, the surface-treated metal sheet according to the present invention will be specifically described while showing examples and comparative examples. Note that the examples shown below are merely examples of the surface-treated metal sheet according to the present invention, and the surface-treated metal sheet according to the present invention is not limited to the examples below.

<Metal plate>
As metal sheets to be used as substrates for the surface-treated metal sheets, eight types of metal sheets (all commercially available) shown in Table 1 below were prepared.

<Surface Treatment Agent for Forming First Coating Layer>
The surface treatment agent for forming the first coating layer was prepared using the quaternary ammonium salt shown in Table 2 below, the silane coupling agent as the organic silicic acid compound shown in Table 3 below, the inorganic component shown in Table 4 below, and the resin component shown in Table 5 below, and pure water as a solvent. In Table 4 below, the column "X1/X2" indicates the mass ratio of the two types of silane coupling agents used. The concentrations of the silane coupling agent as the organic silicic acid compound, the inorganic component, and the resin component were 50 mass%, 10 mass%, and 40 mass%, respectively. Here, the pH just before application of the surface treatment agent (after pH adjustment) is shown in Table 7 below. In addition, the mass percentage (mass%) of the quaternary ammonium salt contained in the film after drying and baking each surface treatment agent, and the molar ratio to the compound having a chemical structure for immobilization are as shown in Table 7 below.

<Surface treatment agent for forming second coating layer>
As the surface treatment agent for forming the second coating layer, the surface treatment agent shown in Table 6 below was prepared. When forming a second coating layer between the metal plate and the first coating layer, the surface treatment agent shown in Table 6 below was applied to the surface of the metal plate in the amount of adhesion shown in Table 6. Next, the surface treatment agent was heated to the maximum temperature shown in Table 6 below, and then cooled to room temperature by the cooling method shown in Table 6 below, and dried and solidified.

<Preparation of surface-treated metal sheet>
The surface treatment agent for forming the first coating layer, which was prepared under the conditions shown in Table 7 below, and the surface treatment agent for forming the second coating layer, which was shown in Table 6, were applied to the metal plate shown in Table 1 by a roll coater method, and multiple surface-treated metal plates were produced for each level.

Each of the surface-treated metal sheets thus produced was examined by the procedure described above to determine whether or not chemical bonds had been properly formed and whether or not they had been properly immobilized.
First, the surface-treated metal plate coated with the first coating layer was cut into a square with a side length of 100 mm to prepare a test piece. The test piece was then immersed in 2 L of boiling water for 10 minutes to remove the quaternary ammonium salt that had not formed a chemical bond. The test piece was dried with a hot air dryer, and a coating sample was taken from the first coating layer. Using this coating sample, the type and amount of compounds detected were investigated by pyrolysis gas chromatography/mass spectrometry. The analysis was performed using a combination of an analyzer GCMS-QP2010 (manufactured by Shimadzu Corporation) and a pyrolysis device JCI-55 (manufactured by Japan Analytical Industry Co., Ltd.). A BD-1 (manufactured by GL Science Co., Ltd.: inner diameter 0.25 mm, length 30 m) was used as the column.

0.4 g of the above-mentioned film sample was wrapped in pyrofilm, and the sample was further wrapped in foil in a helium gas atmosphere, and the foil wrapped in the helium gas atmosphere was irradiated with high frequency waves. As a result, the film sample was held at 255°C for 5 seconds. The generated gas was introduced into the above-mentioned analysis device. Before the gas was introduced into the device, the column was held at 40°C for 5 minutes. After the gas was introduced, the column temperature was changed. It was heated to 150°C at a heating rate of 10°C/sec, and further heated to 280°C at a heating rate of 20°C/sec, and then held at 280°C for 1.5 minutes. The gas introduction temperature was 210°C, the ion source temperature was 210°C, and the mass range m/z was 35 to 500. In addition, in order to quantify trimethylamine, N,N-dimethylethylamine, and chloromethane detected from the above-mentioned film sample, standard substances were also analyzed in the same manner.

A series of analyses was carried out to confirm whether or not N,N-dimethylethylamine, either one or both of the compounds chloromethane, and trimethylamine were detected in a total mass ratio of 3 mg/g or more relative to the first coating layer of interest. If the total amount detected was 3 mg/g or more, it was determined that the compounds had been properly immobilized, and "Yes" was recorded in the "Immobilization Possible" column in Table 7 shown below. On the other hand, if the total amount detected was less than 3 mg/g, it was determined that the compounds had not been properly immobilized, and "No" was recorded in the "Immobilization Possible" column in Table 7 shown below.

Test specimens were prepared using the obtained surface-treated metal plates and evaluated in terms of antiviral properties, long-term stability, and corrosion resistance. The detailed evaluation methods are as follows. The results obtained are summarized in Table 7 below.

<Antiviral>
The antiviral properties were verified by measuring the virus infectivity by the following antiviral test in accordance with the antiviral standards stipulated by the Antibacterial Product Technology Council. A series of tests were carried out based on ISO21702:2019. More specifically, a test piece (dimensions: 50 mm x 50 mm) made from each painted metal plate was placed on a petri dish with the evaluation surface facing up, and a virus suspension containing influenza A was dropped onto the evaluation surface. Then, a film was placed on the test piece to bring the virus suspension into close contact with the entire evaluation surface, and the petri dish was covered with a lid. The petri dish was left to stand for 24 hours in a dark place. The test was carried out in a room at 25 ° C. Then, the virus on the film surface and the evaluation surface surface was washed away, and the virus infectivity (unit: PFU, PFU: Plaque Forming Units) in the obtained washing solution was measured by the plaque measurement method.

In addition to the surface-treated metal sheets, antiviral tests were also conducted on each metal sheet produced without using a quaternary ammonium salt, and the extent to which the viral infectivity of the coated metal sheet had been reduced compared to the viral infectivity of a metal sheet not containing a quaternary ammonium salt was evaluated as an activity value. In view of the fact that the use of the certification seal stipulated by the Antibacterial Product Technology Council is permitted if the virus was reduced by 10 ² or more (in other words, if the activity value was 1 x 10 ² or more), those with an activity value of 1 x 10 ² or more were judged to have passed. In Table 7 below, the obtained activity values are shown as logarithmic values.

<Long-term stability>
Assuming an actual use environment, the surface of the metal plate was wiped clean with a cloth impregnated with 70% ethanol. The pressure during wiping was 6.8 kPa, and the cloth was wiped back and forth 10 times a day. After that, the plate was left to stand for 12 hours in a room with an illuminance of 500 lx. After repeating the above test for 180 days, the antiviral properties were investigated. Those with an activity value of 1 x ¹⁰² or more were judged to have passed the test.

<Corrosion resistance>
The end faces of the test pieces were sealed with tape and subjected to a salt spray test (SST) in accordance with JIS Z 2371:2015 for 72 hours. After the test, the state of rust on the flat surface was observed, and the corrosion resistance was evaluated according to the following evaluation criteria. A pass level was 3 or higher.

(Evaluation criteria)
5: The area where white rust has occurred is less than 1% of the total area on one side of the test piece. 4: The area where white rust has occurred is 1% or more but less than 5% of the total area on one side of the test piece. 3: The area where white rust has occurred is 5% or more but less than 10% of the total area on one side of the test piece. 2: The area where white rust has occurred is 10% or more but less than 30% of the total area on one side of the test piece. 1: The area where white rust has occurred is 30% or more of the total area on one side of the test piece.

As is clear from Table 7 above, the surface-treated metal sheets corresponding to the examples of the present invention exhibited excellent antiviral properties, long-term stability, and corrosion resistance, while the surface-treated metal sheets corresponding to the comparative examples of the present invention failed the evaluation results for antiviral properties or long-term stability.

The above describes in detail preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to such examples. It is clear that a person with ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

The embodiments disclosed herein are illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, or modified in various forms without departing from the scope of the appended claims, the technical scope of the present invention as described below, and the spirit thereof. For example, the components of the above embodiments may be combined in any manner as long as the effects of the components are not impaired. Furthermore, such any combination will naturally provide the functions and effects of each of the components in the combination, and will also provide other functions and effects that will be apparent to a person skilled in the art from the description in this specification.

The effects described in this specification are merely descriptive or exemplary, and are not limiting. In other words, the technology according to the present invention may achieve other effects that are obvious to a person skilled in the art from the description in this specification, in addition to or in place of the above effects.

The following configurations also fall within the technical scope of the present invention.
(1)
The metal plate has a first coating layer provided on at least one surface thereof, the first coating layer including at least an organic silicate compound;
a surface-treated metal sheet, in which a quaternary ammonium salt-containing chemical structure, in which an atomic group R4 of a quaternary ammonium salt having a chemical structure represented by the following chemical formula (1) is chemically bonded to at least one or more immobilizing chemical structures represented by the following chemical formulas (2) to (4), forms a chemical bond with the organosilicate compound, in the first coating layer:
In the following chemical formulas (1) to (4), the atomic groups R1, R2, R3, R4, R11, and R12 are each independently as follows:
R1: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R2: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R3: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R4: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R11: Has a structure represented by -C(R5)(R6)-, where R5 and R6 are each independently a hydrogen atom or a chain hydrocarbon substituent having 1 to 3 carbon atoms.
R12: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R13: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R14: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
(2)
The surface-treated metal sheet according to (1), wherein R1, R2, and R3 in the chemical structure do not have a chemical structure represented by the following chemical formula (5).
In the following chemical formula (5), the atomic groups X1, X2, Ar, and R are each independently as follows:
X1 and X2 each independently represent a hydrogen atom, a chain aliphatic hydrocarbon group having 1 to 3 carbon atoms, or a halogen element, and the chain aliphatic hydrocarbon group may have a hetero element. Here, n is 0, 1, or 2.
Ar: a substituted or unsubstituted aryl group; R: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
-(C(X1)(X2)) _n -Ar-R...chemical formula (5)
(3)
The surface-treated metal sheet according to (1) or (2), wherein the content of the quaternary ammonium salt in the first coating layer is 0.2 mmol or more and 3.0 mmol or less per 1 g of the first coating layer.
(4)
The surface-treated metal sheet according to any one of (1) to (3), wherein in the first coating layer, a molar ratio of the quaternary ammonium salt to at least one of the chemical structures represented by the chemical formulas (2) to (4) is 1.01 to 2.00.
(5)
The surface-treated metal sheet according to any one of (1) to (4), wherein the first coating layer further contains an inorganic component having one or more elements selected from the group consisting of P, V, and Mg.
(6)
The first coating layer further contains a resin,
The surface-treated metal sheet according to any one of (1) to (5), wherein the resin is at least one selected from the group consisting of an acrylic resin, a urethane resin, and a polyester resin.
(7)
The surface-treated metal sheet according to any one of (1) to (6), wherein the first coating layer has an average thickness of 0.02 to 3.00 μm.
(8)
The surface-treated metal sheet according to any one of (1) to (7), wherein a hairline is present on the surface of the metal sheet along the rolling direction of the metal sheet.
(9)
The surface-treated metal sheet according to any one of (1) to (7), wherein a spangle pattern is present on the surface of the metal sheet.
(10)
The surface-treated metal sheet according to any one of (1) to (9), further comprising a second coating layer between the first coating layer and the metal sheet.
(11)
The surface-treated metal sheet according to any one of (1) to (10), wherein the metal sheet is a zinc-based plated steel sheet.
(12)
The surface-treated steel sheet according to any one of (1) to (11), in which, when the surface-treated metal sheet having the first coating layer is immersed in boiling water for 30 minutes and then analyzed by pyrolysis gas chromatography/mass spectrometry, a total of 3 mg/g or more of either or both of N,N-dimethylethylamine and chloromethane compounds, and trimethylamine are detected as a mass ratio relative to the first coating layer.

Reference Signs List 1, 1A Surface-treated metal sheet 10 Metal sheet 20 First coating layer 30 Second coating layer

Claims (12)

The metal plate has a first coating layer provided on at least one surface thereof, the first coating layer including at least an organic silicate compound;
a surface-treated metal sheet, in which in the first coating layer, a quaternary ammonium salt-containing chemical structure, which is a chemical structure in which an atomic group R4 of a quaternary ammonium salt having a chemical structure represented by the following chemical formula (1) is chemically bonded to at least one or more immobilizing chemical structures represented by the following chemical formulas (2) to (4), forms a chemical bond to the organosilicate compound.

In the following chemical formulas (1) to (4), the atomic groups R1, R2, R3, R4, R11, and R12 are each independently as follows:
R1: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R2: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R3: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R4: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R11: Has a structure represented by -C(R5)(R6)-, where R5 and R6 are each independently a hydrogen atom or a chain hydrocarbon substituent having 1 to 3 carbon atoms.
R12: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R13: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.
R14: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 9 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 9 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 9 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.

The surface-treated metal sheet according to claim 1 , wherein R1, R2, and R3 in the chemical structure do not have a chemical structure represented by the following chemical formula (5).

In the following chemical formula (5), the atomic groups X1, X2, Ar, and R are each independently as follows:
X1 and X2 each independently represent a hydrogen atom, a chain aliphatic hydrocarbon group having 1 to 3 carbon atoms, or a halogen element, and the chain aliphatic hydrocarbon group may have a hetero element. Here, n is 0, 1, or 2.
Ar: a substituted or unsubstituted aryl group; R: a substituted or unsubstituted chain aliphatic saturated hydrocarbon group having 1 to 18 carbon atoms, a substituted or unsubstituted chain aliphatic unsaturated hydrocarbon group having 1 to 18 carbon atoms, or a substituted or unsubstituted alicyclic aliphatic hydrocarbon group having 1 to 18 carbon atoms, and at least one of the main chain and the substituent of the atomic group may have a hetero element.

-(C(X1)(X2)) _n -Ar-R...chemical formula (5)
The surface-treated metal sheet according to claim 1 or 2, wherein the content of the quaternary ammonium salt in the first coating layer is 0.2 mmol or more and 3.0 mmol or less per 1 g of the first coating layer. The surface-treated metal sheet according to claim 3, wherein in the first coating layer, the molar ratio of the quaternary ammonium salt to at least one of the chemical structures represented by chemical formulas (2) to (4) is 1.01 to 2.00. The surface-treated metal sheet according to claim 1 or 2, wherein the first coating layer further contains an inorganic component having one or more elements selected from the group consisting of P, V, and Mg. The first coating layer further contains a resin,
The surface-treated metal sheet according to claim 1 , wherein the resin is at least one selected from the group consisting of an acrylic resin, a urethane resin, and a polyester resin. The surface-treated metal sheet according to claim 1 or 2, wherein the average thickness of the first coating layer is 0.02 to 3.00 μm. The surface-treated metal sheet according to claim 1 or 2, wherein the surface of the metal sheet has a hairline along the rolling direction of the metal sheet. The surface-treated metal sheet according to claim 1 or 2, wherein the surface of the metal sheet has a spangle pattern. The surface-treated metal sheet according to claim 1 or 2, further comprising a second coating layer between the first coating layer and the metal sheet. The surface-treated metal sheet according to claim 1 or 2, wherein the metal sheet is a zinc-based plated steel sheet. 3. The surface-treated steel sheet according to claim 1, wherein when a surface-treated metal sheet having the first coating layer is immersed in boiling water for 30 minutes and then analyzed by pyrolysis gas chromatography/mass spectrometry, a total of 3 mg/g or more of either or both of N,N-dimethylethylamine and chloromethane compounds, and trimethylamine are detected in terms of a mass ratio relative to the first coating layer.

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