Inorganic coating liquid, inorganic coating film and instrument having inorganic coating film

Abstract

To provide an instrument which exhibits antibacterial and antiviral properties for a long period of time by simple liquid adjustment and coating without using an expensive material in facilities requiring the use of the instrument having the antibacterial and antiviral properties such as food processing and medical and nursing care.SOLUTION: The present invention is an inorganic coating solution containing a copper ion and phosphoric acid and having a pH value of 2.0 to 6.0. The inorganic coating film has a corrosion layer on a coating film base material and has copper and phosphorus as components on the corrosion layer, and the coating film base material is an organic base material containing a resin and / or a fiber. Further, the present invention is an instrument having the above-mentioned inorganic coating film and exhibiting antibacterial / antiviral performance.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an inorganic coating liquid to be applied to a substrate, an inorganic coating film, and an appliance having an inorganic coating film. [Background technology]

[0002] Since the COVID-19 outbreak, various antibacterial and antiviral products have been attracting attention. In particular, silver-based antibacterial agents, copper-based antibacterial agents, and photocatalysts are being sold as products.

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

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

[0005] Patent Document 3 discloses a coating agent containing at least two types 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 wet area component that includes a base material and a surface layer provided thereon, the wet area component including a (meth)acrylic resin, particles, and an inorganic antiviral agent. [Prior art documents] [Patent documents]

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

[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 [Problem to be solved by the invention]

[0010] Patent Document 1 describes an invention in which a monovalent copper compound is exposed from the surface when a coating film is formed, and also describes that a binder component may be added. Patent Document 2 describes an invention of a foam in which an antibacterial agent is impregnated into a resin. Patent Documents 3 to 5 all describe an inorganic antibacterial / antiviral agent that is impregnated with a binder component, which is applied to a substrate and then dried, thereby adhering the inorganic antibacterial / antiviral agent to the substrate via the binder and maintaining antibacterial / antiviral performance.

[0011] However, inorganic antibacterial and antiviral agents have the effect of inactivating bacteria and viruses and suppressing their proliferation by directly contacting them with inorganic ions or photocatalytic components. Therefore, when binder components are included, the antibacterial and antiviral performance tends to be lower than when no binder components are included.

[0012] Therefore, an antibacterial and antiviral coating agent that does not contain binder components would be ideal, but if it does not contain a binder, it will not be able to maintain adhesion to the substrate, and there is a risk that the antibacterial and antiviral components will easily peel off when the substrate surface is wiped, etc. Therefore, the challenge for all of the above patent documents is to devise binders and other measures to maintain performance over the long term.

[0013] In addition, since there are bacteria that produce odorous components, antibacterial properties also have the effect of suppressing the odors emitted by bacteria.

[0014] The present invention has been made in view of the above-mentioned problems, and its object 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 for a long period of time, a coating film formed after application of this coating liquid, and an appliance having the coating film. [Means for solving the problem]

[0015] The present invention relates to an inorganic coating solution containing at least copper ions and phosphoric acid and having a pH value of 6.0 or less. By using the solution of the present invention to corrode a portion of a substrate during drying or by chemically and / or physically modifying the surface with an acid, the antibacterial and antiviral components bond with the substrate, allowing the antibacterial and antiviral properties to be maintained for a long period of time.

[0016] In addition, after drying, the inorganic coating liquid forms scale-like microparticles, which increases the specific surface area and increases the probability of contact with bacteria and viruses, further improving antibacterial and antiviral performance.

[0017] Solutions containing copper ions usually have a blue color. For example, copper sulfate produces tetraamminecopper ions. It has also been found that adding hydrochloric acid dropwise to a solution containing copper ions produces a pale blue precipitate.

[0018] To impart antibacterial properties, it is sufficient to include a small amount of copper ions. If the concentration of copper ions is low, the blue color of the solution containing copper ions becomes almost transparent, making it possible to ensure transparency when applied to any substrate.

[0019] If the copper ion concentration is low, the pH approaches neutrality. When the pH approaches neutrality, the substrate is not corroded, the substrate does not lose its smoothness, and the substrate does not become uneven. Therefore, when the solution applied to the substrate dries and solidifies, the deposits can be easily wiped off, and the antibacterial and antiviral properties cannot be maintained for a long period of time.

[0020] If the pH can be adjusted to corrode the substrate to a certain extent, remove its smoothness, or create an uneven surface on the substrate, the deposits will be difficult to wipe off even after the solution applied to the substrate dries and solidifies. In particular, in the case of metal substrates, not only will the solution corrode, but the deposited copper ions will bond tightly to the substrate, making them difficult to wipe off.

[0021] However, if the pH is too low, corrosion of the substrate and chemical and / or physical changes caused by the acid on the substrate surface will become severe, making the substrate itself brittle and increasing surface roughness, thereby compromising the original strength and appearance of the substrate.

[0022] In addition to the antibacterial properties of simple copper ions, the antibacterial performance can be further improved by giving the material a microstructure that adsorbs bacteria and viruses. [Effects of the Invention]

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

[0024] [Figure 1] These are SEM images of the inorganic coating film. (a) is a 100x magnification, (b) is a 5000x magnification, and (c) is a 10000x magnification. [Figure 2] Figure 1(b) shows the constituent element image of the precipitate taken by SEM-EDX. The magnification is 5000 times, the same as in Figure 1(b). [Figure 3] This is an optical photograph of SUS304 after the liquid used in Example 1 was applied to the surface and the deposits were polished off. The black areas in the photograph are corroded areas. [Figure 4] FIG. 2 is a schematic diagram of particles of an inorganic coating film and a substrate. [Figure 5] The zirconium substrate was coated with the liquid used in Example 1, dried for 20 days, and then embedded in resin. The substrate was then thinned using a focused ion beam scanning electron microscope (FIB-SEM) system. Images were then observed using a transmission electron microscope (TEM) and analytical images were observed using scanning transmission electron microscope energy dispersive X-ray spectroscopy (STEM-EDS). (a) shows precipitates on the zirconium substrate, (b) shows the area just below the surface of the zirconium substrate, and (c) shows the interior of the zirconium substrate. [Figure 6] This is the plane index of the electron diffraction pattern Cu2P2O7 of "(a) Precipitate on zirconium substrate" shown in Figure 5. [Figure 7] These are Cu2p, P2p, and Cl2p XPS spectra of the product deposited on a SUS304 substrate after drying at room temperature. [Figure 8] These are SEM-EDS images of deposits on PMMA resin, SUS316L, and SUS304 substrates after drying for 8 days to 1 year. Figure a) shows the results after drying for 8 days, b) for 2 months, c) for 3 months, and d) for 1 year. DETAILED DESCRIPTION OF THE INVENTION

[0025] The inorganic coating liquid according to the embodiment is an inorganic coating liquid that is applied to a substrate and dried to form a coating film on the substrate, and contains copper ions and phosphoric acid. It also has antibacterial, antiviral, and deodorizing properties.

[0026] Silver compounds, which are commonly used as antibacterial materials, are easily transformed into Ag2O and other compounds when exposed to light. When the amount exceeds a certain level, they turn black, which can lead to poor appearance, especially in substrates where transparency is required. Platinum compounds are also expensive. For these reasons, the use of copper ions is preferable.

[0027] Substances used to adjust pH include phosphoric acid, as well as at least one of hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphate compounds, pyrophosphate compounds, chlorides, nitrate compounds, sulfate compounds, fluoride, organic acids, amino acids, metal oxides, hydroxides, and aqueous ammonia. Hydrochloric acid, phosphate compounds, chlorides, and amino acids are particularly effective for adjusting pH. Hydrochloric acid is an inexpensive acid, and chlorides are abundant, allowing for greater flexibility in the selection of compounds to react with copper. Furthermore, phosphate compounds can easily form buffer solutions in the weakly acidic range, and amino acids have both amino and carboxyl groups, making it easy to fine-tune the pH in the weakly acidic range.

[0028] When these compounds are used as pH adjusters, counter ions are required, and the counter ions may include at least one of the following elements: sodium, magnesium, aluminum, potassium, calcium, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, tactinium, ruthenium, rhodium, palladium, silver, indium, tin, hafnium, tantalum, tungsten, rhenium, cesium, barium, platinum, and gold.

[0029] The pH adjustment is necessary to prevent corrosion of part of the substrate during drying, to eliminate the smoothness of the substrate surface, or to create an uneven surface on the substrate, and an appropriate adjuster can be used for each substrate.

[0030] The degree of corrosion of the substrate and the degree to which the substrate surface is chemically and / or physically changed by the acid vary depending on the pH value. At a pH of roughly 2.0 or less, the degree of corrosion of the substrate increases. That is, the influence of chemical changes that occur on the substrate surface due to the chemical reaction between the acid and the substrate increases. Alternatively, the degree of physical changes that occur, such as the substrate surface being softened by the coating solution and losing its smoothness, increases. These can cause problems with aesthetics and feel when using tools with an inorganic coating film. As described in Example 3 below, the pH is preferably 2.0 to 6.0, more preferably 3.0 to 5.0.

[0031] In this invention, the inorganic coating solution applied to the substrate becomes an inorganic coating film after drying. Part or all of this inorganic coating film contains scaly, particulate solid matter. This solid matter increases the specific surface area, and not only can it have antibacterial and antiviral properties, but it can also be expected to have deodorizing properties, as odor components are physically adsorbed into the fine gaps between the particles.

[0032] The results of SEM observation of the dried scaly particulate solid material of the present invention are shown in Figure 1. Tiny, overlapping scales resembling moss balls are observed. These particulate solids are not composed of a single component, but are inorganic compound particles containing a mixture of components such as copper and other precious metal ions, chlorine, oxygen, and phosphorus.

[0033] Figure 2 shows an optical photograph of SUS304 after applying an inorganic coating solution to the surface and polishing the deposits. A corrosion layer can be seen beneath the deposits. Figure 4 is a schematic diagram of inorganic coating film particles and the substrate. 1 indicates the substrate, 2 indicates the uneven surface caused by corrosion, and 3 indicates the deposit particles (particulate solids). The deposit particles are spaced apart. After applying the inorganic coating solution, as the coated surface dries, the deposits aggregate at certain points due to surface tension, forming nuclei, from which crystal growth of the deposits begins. Therefore, the solution on the coated surface around the nuclei becomes adsorbed onto the nuclei, and the dissolved material becomes sparse between the nuclei, resulting in the deposit particles being spaced apart. Although there are rare cases where the nuclei are adjacent to each other, in most cases they are spaced apart. Depending on the substrate, applying the coating solution of the present invention causes corrosion due to the acid in the case of metal substrates, and the acid also causes the surface of plastics to lose its smoothness, creating unevenness on the substrate surface. This bonds the substrate and the inorganic compound, preventing easy separation. This is called the SBSCD (Strongly Bonded Scaly Copper Dispersion) structure.

[0034] The substrate may be made of iron, SUS material, or organic substrates such as acrylic resin, polycarbonate resin, or ABS resin, but is not limited to these.

[0035] Equipment 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 commercial kitchenware, cooking utensils, medical equipment, etc. It can also be applied to textile products such as polyester and cotton fabrics. [Example]

[0036] Hereinafter, the embodiment will be described more specifically with reference to examples. [Example]

[0037] Copper (II) phosphate was used as the inorganic compound. 1 part by weight of this copper (II) phosphate was dissolved in 100 parts by weight of 0.1 M diluted hydrochloric acid. The solution was then 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, and the concentration of the inorganic compound was 0.15 wt%.

[0039] When this solution was analyzed by inductively coupled plasma atomic emission spectroscopy (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 liquid was applied to PMMA resin and dried, and the surface of the resulting precipitate, a film, was observed using an SEM with a Hitachi SU-8000. The SEM photograph is shown in Figure 1. In this photograph, scale-like particles were scattered, with some areas that were not scale-like. It was also observed that there were areas where the particles were separated into spherical shapes.

[0041] Using a ULVAC XPS, the samples were analyzed using scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX) with Al-Kα radiation as the X-ray source. The results are shown in Figure 2. As shown in Figure 2, the SEM-EDX analysis aims to identify the constituent elements of precipitates with different shapes. These SEM-EDX analyses provide insight into the chemical composition and mixing state of the material.

[0042] Furthermore, the aggregates composed of particles of 10 μm or less exhibited elements such as Cu, Cl, and O, and the flower-shaped precipitates contained elements such as Cu, P, and O. These flower-shaped precipitates resemble the SEM image of Cu2(OH)PO4 described in Non-Patent Document 1. However, the Cu2(OH)PO4 described in Non-Patent Document 1 is anisotropically cross-linked, peony-shaped petals, and is several tens of μm in size, which differs in size and detailed shape from the Cu2(OH)PO4 of the present invention.

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

[0044] The same liquid as in Example 1 was applied to a SUS304 substrate and dried for 24 hours, after which the particles on the surface of the film that precipitated were scale-like particles similar to those in Example 1. An optical photograph of this film after polishing is shown in Figure 3.

[0045] Thus, it was confirmed that the substrate was corroded even after polishing. When polishing was continued until the corroded area was removed, the corroded surface of the substrate was 0.6 μm. A schematic diagram of the inorganic coating film particles and the substrate is shown in Figure 4. [Example]

[0046] The inorganic coating solution was applied to a SUS304 plate in the same manner as in Example 2, except that the pH value was changed to 1, 2, 4, 5, 6, or 7. The presence or absence of scale-like compounds and the thickness of the corrosion layer were confirmed. A peel test was also conducted using the cross-cut method in accordance with JIS K5600-5-6. The results, including those for the conditions of Example 2 (pH value of 3), are shown in Table 1.

[0047] [Table 1]

[0048] The pH value was between 2 and 6 where scale-like compounds were observed. Furthermore, when the pH value was 2 or less, the thickness of the corrosion layer exceeded 1 μm, resulting in an undesirable appearance. Furthermore, when the pH value was 7, severe peeling occurred, while when the pH value was 5 or less, no peeling occurred. From these findings, it can be said that a pH value of between 2 and 6 is preferable. Even more preferably, the pH value is between 3 and 5, which achieves both the appearance of scale-like compounds and moderate corrosiveness, resulting in a good condition.

[0049] Based on these findings, it is thought that a similar effect would be observed if the base material contained metals that are corroded by acid, such as copper, zinc, aluminum, zirconium, and the iron, nickel, chromium, molybdenum, and tungsten used in SUS materials. [Example]

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

[0051] (a) shows the results of scanning transmission electron microscope-energy dispersive X-ray spectroscopy (STEM-EDS) analysis of the precipitates on the zirconium substrate, (b) just below the substrate surface, and (c) inside the zirconium substrate. Although not as clear as in the schematic diagram in Figure 4, an uneven surface can be seen on the top surface of the substrate. Elements such as Cu, P, Cl, and O, which are not present inside the zirconium substrate, were also detected in the precipitates. From these results, it can be inferred that the precipitates on both the PMMA resin substrate and the zirconium substrate share the same composition of Cu, P, Cl, and O.

[0052] Figure 6 shows the electron diffraction pattern of the precipitate (a) shown in Figure 5. The crystal structure of the precipitate was identified as various copper compounds, including Cu2P2O7, Cu2O, and Cl2Cu2O. These copper compounds are presumably formed by the dissolution and precipitation of ions present in the inorganic coating solution. The diffraction patterns are unclear due to the small number of microcrystals in the precipitates and their low crystallinity. Among them, most of the diffraction patterns were consistent with Cu2P2O7, including the (-202) plane in [1], the (220) plane in [2], the (004) plane in [3], the (204) plane in [5], and the (-406) plane in [6].

[0053] The diffraction patterns of [2] and [3] also matched 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] matched with the (133) plane of Cl2Cu2O, and [6] matched 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 solution as in Example 1 was sprayed onto a 5 cm x 5 cm standard cotton cloth and allowed to dry in a safety cabinet for 24 hours. After that, various antibacterial properties were confirmed using the film adhesion method. The results are shown in Table 2.

[0056] [Table 2]

[0057] The antibacterial activity value is the common logarithm of the ratio of the number of bacteria in a sample treated with an antibacterial agent to the number of bacteria in a comparison control multiplied by (-1). For example, if the number of bacteria in the control is 10,000 and the number of bacteria in the sample is 100, i.e., if the number of bacteria is 1 / 100 of the control, then -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 higher (i.e., the number of bacteria was 1 / 1000 or less of the control) for all bacteria tested, demonstrating excellent antibacterial activity values.

[0058] In addition, the solution was sprayed onto a 5cm x 5cm polyethylene film in the same manner and allowed to dry for 24 hours in a safety cabinet. After that, various antiviral activities were confirmed using the film adhesion method. The results are shown in Table 3.

[0059] [Table 3]

[0060] The antiviral activity value was calculated in the same way as the antibacterial activity value, and the antiviral activity value was also 3.0 or higher for all of the viruses tested, demonstrating excellent antiviral activity values. [Example]

[0061] SUS304 and PMMA resin samples prepared in the same manner as in Examples 1 and 3 were dried at room temperature for 2 weeks, 3 months, 6 months, and 1 year, and their antibacterial activity against Escherichia coli and Staphylococcus aureus was confirmed in accordance with 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 a good value of 2 or more. After 1 year, the antibacterial activity value decreased.

[0064] We also investigated the Cu2p, P2p, and Cl2p spectra of precipitates on SUS304 substrates prepared in the same way for samples dried for 8 days and 1 year. The results are shown in Figure 7. Both the 8-day and 1-year dried samples contained copper, chlorine, and phosphorus spectra. For the Cu2P3 / 2 level of the 8-day dried sample, the binding energies of CuCl, CuCl2, Cu2O, and CuO were 933.2, 935.1, 932.8, and 933.6 eV, respectively. The percentages of CuCl, CuCl2, Cu2O, and CuO determined from the deconvoluted spectra were 26.9, 18.2, 17.4, and 22.4 area percent, respectively.

[0065] The presence of Cl in the precipitation product was characterized using XPS, and the major Cu-Cl bonds in CuCl were located at 198.4 eV and 200.8 eV, respectively, as shown in the Cl spectrum in Figure 7. The presence of P in the precipitation product was also characterized using XPS, and the P 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 Figure 6. The composition of the 1-year dried sample was consistent with that of the 8-day dried sample. However, the proportion of Cu compounds in the 1-year dried sample changed. Compared to the 8-day dried sample, the amount of chlorine tended to increase and the amount of phosphorus tended to decrease in the 1-year dried sample.

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

[0068] [Table 5]

[0069] XPS measurements of deposits on PMMA resin were difficult to obtain due to charge accumulation. XPS evaluated a 0.8 mm diameter area on the substrate. Within this area, deposits were scattered across a 5 mm diameter area. Therefore, the area outside the deposits contained substrate components and a large amount of oxygen. 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 up to 6 months after drying and then decreased. On the coating surface of the inorganic coating solution of the present invention, Cu2P2O7, Cu2O, and Cl2Cu2O precipitated together by a dissolution-deposition mechanism. Initially, the crystallinity of the precipitates was low, and it was expected that the crystals would grow as the coating dried.

[0071] Crystallization was expected to continue for up to 6 months of drying, after which Cu2p became less abundant as the larger growth surface was consumed. Because XPS measurements of PMMA resin were difficult, the time evolution of SBSCD on various substrates was also investigated using SEM-EDX.

[0072] Figure 8 shows SEM-EDS images of SBSCD on PMMA resin, SUS316L, and SUS304 substrates after drying for 8 days to 1 year. After drying for 8 days, elements such as Cu, Cl, P, and O on the PMMA resin substrate were confirmed to be similar to those on SUS304 and SUS316L. No differences in the composition of the deposits were observed between the different substrate types, even with longer drying times.

[0073] Therefore, the dependence of antibacterial activity on the substrate type is thought to be related to the number of crystallites and crystallinity, rather than the type of precipitate.Cu ions are involved in antibacterial activity, and the elution behavior of Cu ions is thought to differ depending on the crystallinity. [Example]

[0074] The same liquid as in Example 1 was applied to a stainless steel kitchen counter, a steam convection handle, a worktop above a dishwasher, and a metal toilet door handle in a restaurant, and then allowed to dry at room temperature for 48 hours. Using a Kikkoman Biochemifa Lumitester and Lucipack Pen, which are commonly used in food processing plants and dental clinics, the ATP levels at the same locations before and after application and drying were measured by the ATP wipe test method.

[0075] ATP values ​​are an alternative method for assessing microbial contamination, and measure the amount of adenosine triphosphate (ATP) that living organisms have as an energy source. ATP values ​​are contained in microorganisms such as bacteria; the more bacteria there are at the measurement point, the higher the ATP value, and the lower the ATP value is when there are fewer bacteria. The ATP swab test method can measure in just a few tens of seconds per location, and when evaluating the same location, the ATP value changes relatively depending on the number of bacteria, making it easier to check the hygiene status of a managed location than conventional antibacterial tests. The ATP value results are shown in Table 6.

[0076] [Table 6]

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

[0078] Although the food processing field has been described in this example, the present invention can be widely applied to fields requiring antibacterial properties, such as medical care, nursing care, and pediatric facilities. [Industrial Applicability]

[0079] As described above, the present invention uses an inorganic coating solution containing copper ions and phosphoric acid and with a pH of 6.0 or less to create an antibacterial film that has strong adhesion to the coating substrate, forms a scale-like coating, and is both highly durable and antibacterial. This antibacterial film does not require expensive materials and achieves high functionality through simple solution adjustment and coating, making it applicable to a wide range of fields and highly valuable in industry. [Explanation of symbols]

[0080] 1 Base material 2. Uneven surface caused by corrosion 3 Precipitate particles

Claims

1. An inorganic coating solution containing copper ions and phosphoric acid and having a pH value of 2.0 to 6.

0.

2. 2. The inorganic coating liquid according to claim 1, which has a pH value of 3.0 to 5.

0.

3. 3. The inorganic coating liquid according to claim 1, which contains at least one of hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, a phosphate compound, a pyrophosphate compound, a chloride, a nitrate compound, a sulfate compound, a fluoride, an organic acid, an amino acid, a metal oxide, a hydroxide, and aqueous ammonia.

4. The coating film has a corrosion layer on a substrate, and an inorganic coating film having copper and phosphorus as components on the corrosion layer.

5. 5. The inorganic coating film according to claim 4, wherein the corroded layer is a chemically and / or physically altered substrate.

6. 6. The inorganic coating film according to claim 4, wherein the corrosion layer has irregularities and contains a metal oxide.

7. 6. The inorganic coating film according to claim 4, wherein the coating substrate contains at least one metal material selected from the group consisting of copper, zinc, aluminum, zirconium, iron, nickel, chromium, molybdenum, and tungsten.

8. 6. The inorganic coating film according to claim 4, wherein the thickness of the corrosion layer on the coated substrate is 1 μm or less.

9. An inorganic coating film in which the coating substrate is an organic substrate containing resin and / or fiber.

10. 10. The inorganic coating film according to claim 9, wherein the surface of the resin and / or fiber is chemically and / or physically changed, and the changed surface contains copper and phosphorus as components.

11. 10. The inorganic coating film according to claim 4 or 9, comprising particulate solid matter having a scaly surface structure.

12. 10. The inorganic coating film according to claim 4 or 9, wherein the particulate solids are spaced apart.

13. 3. An inorganic coating film obtained by drying the inorganic coating liquid according to claim 1 or 2.

14. A device having the inorganic coating film according to claim 4 or 9, and exhibiting antibacterial and antiviral properties.

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