Inorganic coating solution, inorganic coating film, and device having inorganic coating film

Abstract

This project provides equipment that exhibits long-term antibacterial and antiviral properties through simple liquid preparation and coating, without using expensive materials, to facilities that require the use of antibacterial and antiviral equipment, such as those in food processing, medical care, and nursing care. [Solution] The present invention relates to an inorganic coating solution containing copper ions and phosphoric acid and having a pH value of 2.0 to 6.0. The present invention also relates to a coating substrate having a corrosion layer and an inorganic coating film containing copper and phosphorus as components on the corrosion layer, and an inorganic coating film in which the coating substrate is an organic substrate containing resin and / or fiber. The present invention also relates to an appliance having the above inorganic coating film and exhibiting antibacterial and antiviral properties.

Description

Technical Field

[0001] The present invention relates to an inorganic coating liquid for coating a substrate, an inorganic coating film, and an instrument having the inorganic coating film.

Background Art

[0002] After the novel coronavirus infection, products aimed at various antibacterial and antiviral purposes have attracted attention. In particular, silver-based antibacterial agents, copper-based antibacterial agents, photocatalysts, etc. are sold as products.

[0003] Patent Document 1 discloses an antiviral paint containing particles of a monovalent copper compound selected from at least one kind from the group consisting of CuCl, Cu(CH3COO), CuI, CuBr, Cu2S, CuCN, and CuSCN as an active ingredient for inactivating viruses, and the viruses are inactivated by the particles of the monovalent copper compound exposed from the surface when a coating film is formed.

[0004] Patent Document 2 discloses a polyolefin-based extruded resin foam excellent in foaming property, which contains a phosphate-based compound carrying silver or a silver compound or silver ions in a range of 0.8 to 5.0 parts by mass with respect to 100 parts by mass of a polyolefin resin.

[0005] Patent Document 3 discloses a coating agent containing at least two kinds of photocatalysts and a binder.

[0006] Patent Document 4 discloses an antiviral aqueous overcoat composition containing a binder component, a copper compound, and water.

[0007] Patent Document 5 discloses a water-related member including a substrate and a surface layer provided thereon, and the water-related member contains a (meth)acrylic resin, particles, and an inorganic antiviral agent.

Prior Art Documents

Patent Documents

[0008] [Patent Document 1] Japanese Patent No. 5723097 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2022-119552 [Patent Document 3] Japanese Patent No. 7190265 [Patent Document 4] Japanese Unexamined Patent Application Publication No. 2023-072599 [Patent Document 5] Japanese Unexamined Patent Application Publication No. 2024-001735 [Non-Patent Document]

[0009] [Non-Patent Document 1] Siyuan Yang, Kejia Xu, Hongjuan Wang, Hao Yu, Shanqing Zhang, Feng Peng, Solution growth of peony-like copper hydroxyl-phosphate(Cu2(OH)PO4) flowers on Cu foil and their photocatalytic activity under visible light, Materials & Design, Volume 100, 2016, Page 30-36 [Summary of the Invention] [Problems to be Solved by the Invention]

[0010] Patent Document 1 is an invention in which a monovalent copper compound is exposed from the surface when a coating film is formed, and there is a description that a binder component may be added. Patent Document 2 is an invention of a foam containing an antibacterial agent in a resin. Patent Documents 3 to 5 all involve applying an inorganic antibacterial and antiviral agent containing a binder component to a substrate and drying it, so that the inorganic antibacterial and antiviral agent adheres to the substrate through the binder to maintain antibacterial and antiviral performance.

[0011] However, inorganic antibacterial and antiviral agents can inactivate bacteria and viruses and inhibit their growth by directly contacting bacteria or viruses with inorganic ions or photocatalyst components. Therefore, when a binder component is included, the antibacterial and antiviral performance tends to decrease compared to the case without the binder component.

[0012] Therefore, an antibacterial and antiviral coating agent without a binder component is ideal. However, without a binder, the adhesion to the substrate cannot be maintained, and there is a risk that the antibacterial and antiviral components will be easily peeled off by wiping the substrate surface or the like. Therefore, in any of the above patent documents, it is a problem to devise a binder or the like to maintain the performance for a long time.

[0013] In addition, since there are bacteria that generate odor components, the antibacterial performance also has the effect of suppressing the odor emitted by bacteria.

[0014] The present invention has been made in view of the above problems, and an object thereof is to provide a coating liquid that does not contain a binder component, adheres to a substrate, and maintains excellent antibacterial, antiviral, and deodorizing performance over a long period of time, a coating film after applying this coating liquid, and a device having the coating film.

Means for Solving the Problems

[0015] The present invention is an inorganic coating liquid containing at least copper ions and phosphoric acid and having a pH value of 6.0 or less. Further, by using the liquid of the present invention and corroding a part of the substrate during drying, or chemically and / or physically changing its surface with an acid, the antibacterial and antiviral components can be bonded to the substrate, and the antibacterial and antiviral performance can be maintained over a long period of time.

[0016] In addition, after drying the inorganic coating liquid, by forming scaly fine particles, the specific surface area becomes large, the contact probability with bacteria, viruses, etc. increases, and the antibacterial and antiviral performance can be further improved.

[0017] Generally, the color of a solution containing copper ions exhibits blue. For example, in the case of copper sulfate, it becomes tetraamminecopper ions. Also, it has been found that when hydrochloric acid is dropped into a solution containing copper ions, a pale blue precipitate is formed.

[0018] To impart antibacterial properties, it is sufficient to contain a small amount of copper ions. If the copper ions are at a low concentration, the blue color of the solution containing copper ions becomes almost transparent, and transparency can be ensured when applied to any substrate.

[0019] If the copper ions are at a low concentration, the pH approaches almost neutral. When approaching neutrality, the substrate will not be corroded, the smoothness of the substrate will not be lost, or uneven surfaces will not be formed on the substrate. Therefore, when the solution applied to the substrate dries and solidifies, the precipitate can be easily wiped off, and antibacterial and antiviral properties cannot be maintained over a long period.

[0020] If the pH is adjusted to corrode the substrate to some extent, eliminate the smoothness of the substrate, or create an uneven surface on the substrate, it becomes difficult to easily wipe off the precipitate even when the solution applied to the substrate dries and solidifies. Especially in the case of a metal substrate, not only will it corrode, but the precipitated copper ions will strongly bond to the substrate, making it impossible to easily wipe off.

[0021] However, if the pH is too low, the corrosion of the substrate and the chemical and / or physical changes due to the acid on the substrate surface become intense. The substrate itself becomes brittle and the surface roughness worsens, deteriorating the original strength and appearance of the substrate.

[0022] Also, not only the antibacterial property of simple copper ions, but also by providing a fine structure that adsorbs bacteria and viruses, the antibacterial performance can be further improved.

Effects of the Invention

[0023] According to the present invention, by using an inorganic coating liquid, an inorganic coating film, and an instrument having the inorganic coating film, it is possible to provide a product that exhibits stable antibacterial and antiviral performance over a long period of time.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

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Figure 8

Mode for Carrying Out the Invention

[0025] The inorganic coating liquid according to the embodiment is an inorganic coating liquid that is applied to a substrate and forms a coating film on the substrate through a drying process, and contains copper ions and phosphoric acid. Also, it mainly has antibacterial, antiviral, and deodorizing properties.

[0026] Silver compounds commonly used as antibacterial materials are easily altered to Ag2O etc. by light irradiation, and blackening occurs when a certain amount or more is reached. Especially in the case of a substrate where transparency is expected, the appearance may deteriorate. Also, platinum compounds are costly. For these reasons, the use of copper ions is desirable.

[0027] The substance for pH adjustment contains phosphoric acid, and further contains at least one of hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphate compounds, pyrophosphate compounds, chlorides, nitrate compounds, sulfate compounds, fluorides, organic acids, amino acids, metal oxides, hydroxides, and aqueous ammonia. In particular, hydrochloric acid, phosphate compounds, chlorides, and amino acids are effective for pH adjustment. Hydrochloric acid is inexpensive as an acid and there are many chlorides, and there is a large degree of freedom in the selection of compounds when reacting with copper. Also, phosphate compounds can easily create a buffer solution in the weak acidic region, and amino acids have both an amino group and a carboxyl group, and can easily fine-tune the pH in the weak acidic region.

[0028] When using these compounds as pH adjusters, their counterions are required, and as elements, at least one or more of sodium, magnesium, aluminum, potassium, calcium, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, indium, tin, hafnium, tantalum, tungsten, rhenium, cesium, barium, platinum, and gold may be required.

[0029] Performing pH adjustment is necessary to corrode part of the substrate during drying, eliminate the smoothness of the substrate surface, or create an uneven surface on the substrate, and corresponding preparation agents can be used for each substrate.

[0030] Depending on the pH value, the degree of corrosion of the substrate and the degree to which the substrate surface chemically and / or physically changes due to the acid differ. Generally, when it is pH 2.0 or less, the degree of corrosion of the substrate increases. That is, the influence of chemical changes in which the surface of the substrate changes due to a chemical reaction with the acid becomes greater. Alternatively, the degree of physical changes such as the surface of the substrate being softened by the coating liquid and the smoothness being impaired increases. These are the causes of problems such as aesthetics and touch when using instruments having an inorganic coating film. As described in Example 3 to be described later, the pH is preferably 2.0 to 6.0, more preferably 3.0 to 5.0.

[0031] In the present invention, the inorganic coating liquid applied to the substrate becomes an inorganic coating film after drying. Scaly particulate solids are formed in part or all of this inorganic coating film. Due to this solid, the specific surface area increases, and not only antibacterial and antiviral properties but also deodorizing performance due to physical adsorption of odor components in the fine gaps between the fine particles can be expected.

[0032] The results of SEM observation of the scaly particulate solids after drying in the present invention are shown in FIG. 1. What became a moss ball shape that was fine and overlapped in a scaly shape was observed. This particulate solid is not a single component but an inorganic compound particle in which components such as noble metal ions such as copper, chlorine, oxygen, and phosphorus are mixed.

[0033] Figure 2 shows an optical photograph of SUS304 after applying an inorganic coating solution thereon and polishing the precipitate. A corrosion layer can be seen under the precipitate. Figure 4 is a schematic diagram of the particles of the inorganic coating film and the substrate. 1 represents the substrate, 2 represents the uneven surface due to corrosion, and 3 represents the precipitate particles (particulate solids). The precipitate particles exist separately. After applying the inorganic coating solution, as the coated surface dries, the precipitate aggregates at certain points due to surface tension to form nuclei, and crystal growth of the precipitate starts from these nuclei. Therefore, the solution on the coated surface around the nuclei comes to adsorb to the nuclei, and the dissolved matter becomes sparse between the nuclei, so that the precipitate particles come to exist separately. Although the nuclei may rarely be adjacent to each other, in most cases they are separated. Depending on the substrate, when the coating solution of the present invention is applied, in the case of a metal substrate, a corrosive action by an acid occurs, and for plastics etc., the smoothness of the substrate surface is lost due to the acid, and unevenness is formed on the substrate surface. Thereby, the substrate and the inorganic compound are bonded and do not easily peel off. This will be referred to as the SBSCD (Strongly Bonded Scaly Copper Dispersion) structure.

[0034] The substrate may be iron, a SUS material, or an organic substrate such as an acrylic resin, a polycarbonate resin, or an ABS resin, but is not limited thereto.

[0035] The device coated with this inorganic coating film is expected to have stable antibacterial and antiviral properties over a long period of time, and can be applied to household and business kitchen utensils, cooking utensils, and medical devices, etc. Furthermore, it can also be applied to fiber products such as polyester and cotton cloth.

Example

[0036] Hereinafter, examples will be shown to more specifically explain the embodiments.

Example

[0037] As an inorganic compound, copper(II) phosphate was used. 1 part by weight of this copper(II) phosphate was dissolved in 100 parts by weight of 0.1 M dilute hydrochloric acid. Further, it was mixed with 0.1 M sodium hydroxide, 0.1 M phosphoric acid, and 0.1 M aqueous ammonia to adjust the pH.

[0038] The pH of the solution after pH adjustment was 3.0. Also, the concentration of the inorganic compound was 0.15 wt%.

[0039] When this solution was analyzed by inductively coupled plasma atomic emission spectrometry (ICP - AES), Cu 2+ = 140 mg / L, Ca 2+ = 0.11 mg / L, Cl - = 33 mg / L, HPO4 2- = 12.0 mg / L.

[0040] This solution was applied onto a PMMA resin, dried, and the surface of the deposited film was observed by SEM using SU - 8000 manufactured by Hitachi, Ltd. The SEM photograph is shown in Figure 1. In this photograph, scaly particles were scattered, and there were also some parts that were not scaly. Also, it was observed that there were some parts where the particles were separated in a spherical shape.

[0041] Using an XPS manufactured by ULVAC, with Al - Kα rays as the X - ray source, it was analyzed by scanning electron microscope energy - dispersive X - ray spectroscopy (SEM - EDX). The results are shown in Figure 2. As shown in Figure 2, SEM - EDX aims to identify the constituent elements of precipitates with different shapes. Through these SEM - EDX analyses, the chemical composition and mixing state of the material can be understood.

[0042] Also, the aggregates composed of particles of 10 μm or less showed components such as Cu, Cl, and O, and the flower - shaped precipitates contained components such as Cu, P, and O. This flower - shaped precipitate is similar to the SEM image of Cu2(OH)PO4 in Non - Patent Document 1. However, the Cu2(OH)PO4 in Non - Patent Document 1 is peony - shaped with anisotropic cross - linked petals and has a size of several tens of μm, and its size and fine shape are different from those of the Cu2(OH)PO4 of the present invention.

[0043] In this example, PMMA resin was used, but similar films were also formed with ABS resin or standard cotton cloth.

Example

[0044] A liquid similar to that in Example 1 was applied onto a SUS304 substrate and dried for 24 hours. After that, the particles on the surface of the deposited film were the same scaly particles as in Example 1. An optical photograph of this polished film is shown in Figure 3.

[0045] In this way, it was confirmed that the substrate was corroded even after polishing. When polishing was continued until the corroded part disappeared, the corroded surface of the substrate was 0.6 μm. A schematic diagram of the particles of this inorganic coating film and the substrate is shown in Figure 4.

Example

[0046] An inorganic coating liquid was applied onto a SUS304 plate in the same manner as in Example 2 except that the pH values were 1, 2, 4, 5, 6, and 7, and the presence or absence of the appearance of scaly compounds and the thickness of the corrosion layer were confirmed. Also, in accordance with JIS K5600-5-6, a peel test was conducted by the cross-cut method. Table 1 shows the results including the results under the conditions of Example 2 (pH value of 3).

[0047]

Table 1

[0048] Scaly compounds were observed when the pH value was 2 or more and 6 or less. Also, when the pH value was 2 or less, the thickness of the corrosion layer exceeded 1 μm, and the appearance was also in an unfavorable state. Furthermore, when the pH value was 7, peeling was severe, and a phenomenon where there was no peeling when the pH value was 5 or less was observed. From these facts, it can be said that a pH value of 2 or more and 6 or less is preferable. More preferably, the pH value is 3 or more and 5 or less, where the appearance of scaly compounds and appropriate corrosiveness are compatible, resulting in a good state.

[0049] From these facts, it is considered that the same effect will be exhibited if metals corroded by acids, that is, iron, nickel, chromium, molybdenum, tungsten, etc. used in copper, zinc, aluminum, zirconium, and SUS materials, are contained in the base material.

Example

[0050] Using the solution prepared in the same manner as in Example 1, it was applied onto a zirconium substrate. For cross-sectional observation, the zirconium substrate after being coated with the solution of Example 1 and dried for 20 days was embedded in resin, thinned using a focused ion beam scanning electron microscope (FIB-SEM) system, and then confirmed with a transmission electron microscope (TEM). The results are shown in Fig. 5.

[0051] (a) shows the precipitate on the zirconium substrate, (b) shows the area just below the substrate surface, and (c) shows the results of scanning transmission electron microscope energy-dispersive X-ray spectroscopy (STEM-EDS) analysis inside the zirconium substrate. Although it is not as clear as the schematic diagram in Fig. 4, uneven surfaces can be seen on the upper surface of the substrate. Also, elements such as Cu, P, Cl, and O that do not exist inside the zirconium substrate were detected in the precipitate. From these results, it is speculated that the precipitates on both the PMMA resin substrate and the zirconium substrate share the same composition of Cu, P, Cl, and O.

[0052] Fig. 6 shows the electron diffraction pattern of the precipitate (a) shown in Fig. 5. The crystal structure of the precipitate was identified as various copper compounds such as Cu2P2O7, Cu2O, and Cl2Cu2O. It is speculated that these copper compounds were formed by the dissolution and precipitation of ions present in the inorganic coating solution. Since the number of microcrystals in the precipitate is small and the crystallinity is low, it can be seen that the diffraction pattern is not clear. Among them, many diffraction patterns match Cu2P2O7, which are the (-202) plane of [1], the (220) plane of [2], the (004) plane of [3], the (204) plane of [5], and the (-406) plane of [6].

[0053] The diffraction patterns of [2] and [3] were consistent with those of Cu2O and Cl2Cu2O. [2] was also present on the (211) plane of Cu2O and the (222) plane of Cl2Cu2O, and [3] was also present on the (220) plane of Cu2O and the (331) plane of Cl2Cu2O. Furthermore, [4] was consistent with the (133) plane of Cl2Cu2O, and [6] was consistent with the (332) plane of Cu2O.

[0054] There were three crystals that matched the obtained electron diffraction pattern, suggesting that the precipitate was a mixture of Cu2P2O7, Cu2O, and Cl2Cu2O.

Example

[0055] 1 mL of the same liquid as in Example 1 was sprayed onto a 5 cm × 5 cm standard cotton cloth and dried in a safety cabinet for 24 hours. Then, various antibacterial properties were confirmed by the film adhesion method. The results are shown in Table 2.

[0056]

Table 2

[0057] The antibacterial activity value indicates the common logarithm value × (-1) of the ratio of the number of bacteria in the sample treated with the antibacterial agent to the number of bacteria in the comparison control. For example, when the number of bacteria in the control is 10,000 and the number of bacteria in the sample is 100, that is, when the number of bacteria becomes 1 / 100 compared to the control, -log(100 / 10,000) = 2.0. In the case of the present invention, as shown in Table 2, the antibacterial activity value was 3.0 or more for all the bacteria tested (that is, the number of bacteria was 1 / 1000 or less compared to the control), indicating excellent antibacterial activity.

[0058] Also, similarly, it was sprayed onto a 5 cm × 5 cm polyethylene film and dried in a safety cabinet for 24 hours. Then, various antiviral properties were confirmed by the film adhesion method. The results are shown in Table 3.

[0059]

Table 3

[0060] Similar to the antibacterial activity value, the antiviral activity value is also calculated by the same method. In all the viruses tested, the antiviral activity value was 3.0 or higher, indicating excellent antiviral activity.

Example

[0061] SUS304 and PMMA resin samples prepared in the same manner as in Example 1 and Example 3 were dried at room temperature for 2 weeks, 3 months, 6 months, and 1 year, and the antibacterial activity values against Escherichia coli and Staphylococcus aureus were confirmed according to JIS Z2801. The results are shown in Table 4.

[0062]

Table 4

[0063] As shown in Table 4, up to 6 months, the antibacterial activity value was 2 or higher, which was a good value. After 1 year, the antibacterial activity value decreased.

[0064] Also, the Cu2p, P2p, and Cl2p spectra of the deposits on the SUS304 substrate of the samples on the 8th day and after 1 year prepared in the same manner were confirmed. The results are shown in Figure 7. Spectra of copper, chlorine, and phosphorus were present in both the samples dried for 8 days and 1 year. In the case of the Cu2P3 / 2 level of the sample dried for 8 days, the binding energies of CuCl, CuCl2, Cu2O, and CuO were 933.2, 935.1, 932.8, and 933.6 eV, respectively. The ratios of CuCl, CuCl2, Cu2O, and CuO determined from the deconvoluted spectra were 26.9, 18.2, 17.4, and 22.4 area%, respectively.

[0065] The presence of Cl in the deposited product was characterized using XPS. The main Cu-Cl bonds in CuCl were located at 198.4 eV and 200.8 eV, respectively, as shown in the Cl spectrum of Figure 7. Also, the presence of P in the deposited product was characterized using XPS, and PO4 3-and P2O7 2- were located at 132.9 eV and 133.8 eV, respectively.

[0066] Therefore, chlorine and phosphorus were incorporated into CuO during the drying process, which is consistent with the EDS results in Fig. 6. Also, the components of the dried samples for one year were the same as those of the samples dried for eight days. However, the proportion of the Cu compound in the samples dried for one year changed. Compared with the samples dried for eight days, the amount of chlorine tended to increase and the amount of phosphorus tended to decrease in the samples dried for one year.

[0067] Table 5 shows the atomic % values of O1s, P2p, Cl2p, and Cu2p from the deconvoluted spectra.

[0068]

Table 5

[0069] XPS measurement of the deposit on the PMMA resin was difficult to obtain data due to charge accumulation. XPS evaluates a region with a diameter of 0.8 mm on the substrate. Within this region, the deposits are scattered with a diameter of 5 mm. Therefore, there are many substrate components and oxygen in the region outside the deposits. On all substrates, the amount of P2p decreased and the amount of Cl2p increased with drying.

[0070] On the other hand, the Cu content increased until six months after drying and then decreased. On the coating surface of the inorganic coating liquid of the present invention, Cu2P2O7, Cu2O, and Cl2Cu2O were deposited together by a dissolution-deposition mechanism. At the beginning of the compound deposition, the crystallinity of the deposit was low, and it was expected that the crystals would grow as drying proceeded.

[0071] Crystallization was expected to continue until six months of the drying period, but after that, the larger growth surface was consumed, so Cu2p decreased. Since XPS measurement of the PMMA resin was difficult, the time change of SBSCD on various substrates was also examined by SEM-EDX.

[0072] Figure 8 shows SEM-EDS of SBSCD on PMMA resin, SUS316L, and SUS304 substrates after drying for 8 days to 1 year. After drying for 8 days, components such as Cu, Cl, P, and O on the PMMA resin substrate could be confirmed in the same way as on SUS304 and SUS316L. Even when the drying time was long, no difference was found in the composition of the deposits among different substrate types.

[0073] Therefore, it is considered that the dependence of antibacterial properties on the substrate type is related to the number and crystallinity of crystallites rather than the type of deposits. Cu ions are involved in antibacterial properties, and it is considered that the elution behavior of Cu ions differs depending on the crystallinity.

Example

[0074] The same liquid as in Example 1 was applied to SUS cooking tables in restaurants, steam convection handles, upper worktables of dishwashers, and metal toilet door handles, and dried at room temperature for 48 hours. Using a Kikkoman Biochemifa Lumitester and Lucipac Pen commonly used in food processing factories and dentistry, the ATP values at the same locations before and after application and drying were measured by the ATP wiping test method.

[0075] The ATP value is an alternative method for evaluating microbial contamination and is a method for measuring the amount of adenosine triphosphate (ATP) that organisms have as an energy source. The ATP value is contained in microorganisms such as bacteria. When there are many bacteria at the measurement location, the ATP value becomes high, and when there are few bacteria, the ATP value becomes low. Since the ATP wiping test method can be measured in dozens of seconds for one location, for the evaluation of the same location, the ATP value changes relatively depending on the number of bacteria, so the hygiene status of the management location can be confirmed more simply than in conventional antibacterial tests. The results of the ATP values are shown in Table 6.

[0076]

Table 6

[0077] From Table 6, it can be seen that the inorganic coating liquid of Example 1 was applied to all the measurement locations, and the ATP value decreased after drying.

[0078] In this example, the food processing field has been described. However, the present invention can be widely applied to fields that require antibacterial properties, such as medical, nursing, and pediatric facilities.

Industrial Applicability

[0079] As described above, in the present invention, an antibacterial film that contains copper ions and phosphoric acid, has a pH value of 6.0 or less, has a strong adhesion force with the coating film substrate, is scaly, and can achieve both high durability and antibacterial properties has been realized. This antibacterial film does not use expensive materials and can achieve high functionality through simple liquid adjustment and coating. Therefore, it can be applied to a wide range of fields and has extremely high industrial value.

Explanation of Symbols

[0080] 1 Substrate 2 Concave and convex surface due to corrosion 3 Precipitated particles

Claims

1. A method for forming an inorganic coating film containing copper and phosphorus derived from the copper ions and phosphoric acid by forming irregularities having a thickness of 0.1 to 1.0 μm on a substrate described in any one or more of the following (1) to (4) using an inorganic coating liquid containing copper ions and phosphoric acid and having a pH value of 2.0 to 6.0: (1) A metal substrate containing one or more of copper, zinc, aluminum, zirconium, iron, nickel, chromium, molybdenum, and tungsten. (2) Organic substrates containing one or more of acrylic resin, polycarbonate resin, and ABS resin (3) Substrate containing standard cotton cloth (4) Substrate containing polyethylene

2. 2. The method for forming an inorganic coating film according to claim 1, wherein the pH value is 3.0 to 5.

0.

3. 3. The method for forming an inorganic coating film according to claim 1, wherein the inorganic coating solution contains at least one of hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphate compounds, pyrophosphate compounds, chlorides, nitrate compounds, sulfate compounds, fluorides, organic acids, amino acids, metal oxides, hydroxides, and aqueous ammonia.

4. 3. An inorganic coating film produced by the method for forming an inorganic coating film according to claim 1, wherein the inorganic coating solution contains a metal oxide, and the irregularities formed on the substrate contain the metal oxide.

5. 5. The inorganic coating film according to claim 4, wherein particulate solid matter having a scale-like structure is deposited on the irregularities formed on the substrate.

6. 6. The inorganic coating film according to claim 5, wherein the particulate solids are spaced apart.

7. An appliance having the inorganic coating film according to claim 4 and exhibiting antibacterial and antiviral properties.

Images