JP7680013B2 - Coating material and coating method - Google Patents

Description

The present invention relates to a coating material and a coating method used to modify the surface of an object to be coated.

Conventionally, various articles made of materials such as resin, metal, wood, and rubber are treated as objects to be coated, and a coating material is applied or sprayed onto the surface to form a coating film, thereby enhancing the antiviral properties of the surface of the object to be coated (see Patent Document 1).

JP 2018-172306 A (page 3)

However, in Patent Document 1, the coating material sprayed on the surface of the article penetrates into minute irregularities on the surface of the article and forms a coating film in a provisionally adhered state, which causes the coating film to chip or peel off over time, meaning that the antiviral effect cannot be sustained for a long period of time.

In particular, in recent years, due to the spread of the novel coronavirus (COVID-19), there is a demand for modifications to the surfaces of various items that people come into contact with that can provide a high level of antiviral activity that can be maintained for a long period of time.

The present invention was made with a focus on these problems, and aims to provide a coating material and coating method that can maintain a high antiviral effect on the surface of the object to be coated for a long period of time.

In order to solve the above problems, the coating material of the present invention is
The coating agent is prepared by dissolving polysilazane and an alkylsilicate condensate in an inert solvent at a total concentration of 50 to 80% by mass as a base agent, and adding an antiviral agent to the base agent at a ratio of 0.1 to 20% by mass.
According to this feature, the antiviral agent is stably fixed to the surface of the glass coating film produced from polysilazane and an alkyl silicate condensate as a base material, with a large exposed area secured on the surface layer of the coating, and therefore the high antiviral effect of the object coated with this coating material can be maintained for a long period of time.

The polysilazane is characterized in that it is an inorganic polysilazane.
According to this feature, the glass coating film can be easily formed into a thin film, and therefore the antiviral agent can be easily exposed on the surface layer of the film.

The antiviral agent is characterized in that it is an organic antiviral agent.
According to this feature, by using inorganic polysilazane as a base agent and an organic antiviral agent having a relatively low affinity with the base agent, the base agent is less likely to adhere to the surface of the antiviral agent due to surface tension, and a larger exposed area of the antiviral agent can be ensured on the surface layer of the glass coating film.

Further, an antibacterial agent is added in an amount of 0.1 to 10% by mass.
This feature makes it possible to enhance both the antibacterial effect and the antiviral effect of the object to be coated.

The coating method of the present invention comprises the steps of:
The present invention is characterized by including a coating step in which a surface of an object to be coated is coated with a coating material obtained by adding an antiviral agent to a base agent, the base agent being prepared by dissolving polysilazane and an alkyl silicate condensate in an inert solvent at a concentration of 50 to 80% by mass in total.
According to this feature, a glass coating film made of polysilazane and an alkyl silicate condensate is formed on the surface of the object to be coated, and the antiviral agent is stably fixed to the glass coating film as a base material, with a large exposed portion secured on the surface layer, so that the object to be coated can have a high antiviral effect over a long period of time.

The coating step is characterized in that it is a step of forming a thin coating film, which serves as a base material mainly composed of SiO2, on the surface of the object to be coated, and exposing the antiviral agent on the surface of the coating film.
According to this feature, by exposing the antiviral agent on the surface of the coating film, the antiviral agent acts directly on various viruses, and a high antiviral effect can be maintained for a long period of time. Furthermore, by forming the coating film in a thin layer, it is possible to ensure the ability to follow the behavior of the surface of the object to be coated.

The coating process is characterized in that it is a process in which the coating material is applied to the surface of the object to be coated to which moisture has adhered, and a component contained in the coating material is caused to chemically react with the moisture adhered to the surface of the object to be coated, thereby producing a coating film serving as a base material containing SiO2 as a main component on the surface of the object to be coated, and the antiviral agent is exposed in recesses in the surface of the coating film formed by the chemical reaction.
According to this feature, the antiviral agent is exposed in recesses on the surface of the coating film, which are generated by the emission of gas resulting from a chemical reaction between the components contained in the coating material and the moisture on the surface of the object to be coated. This allows the antiviral agent to act directly on various viruses, thereby maintaining a high antiviral effect for a long period of time.

The coating step is characterized in that it is a step of coating the surface of the object to be coated with the coating material containing the antiviral agent, the antiviral agent being composed of particles having a maximum diameter of 1 μm, to a thickness of 500 nm or less.
According to this feature, the antiviral agent can be reliably exposed on the surface of the coating film.

The method is characterized in that it includes a sterilization step of sterilizing the surface of the object to be coated prior to the coating step.
According to this feature, a high-quality, long-lasting coating film can be formed on the surface of the object to be coated that has been cleaned by the sterilization process.

The method is characterized by having a pretreatment step of adhering moisture to the surface of the object to be coated prior to the coating step.
According to this feature, by adhering moisture to the surface of the object to be coated, a chemical reaction between the moisture and the components contained in the coating material is promoted, making it possible to rapidly and firmly produce a coating film on the surface of the object to be coated.

4( a ) to 4 ( c ) are cross-sectional views showing in chronological order the mechanism by which a coating film is formed on the article in Example 1. FIG. 2 is an enlarged view of the area enclosed by the dotted line in FIG. FIG. 3 is an enlarged view of the area enclosed by the dotted line in FIG. 2 . FIG. 2 is an enlarged view of the area surrounded by the dotted line in FIG. 1( c ) in another embodiment of the first embodiment. FIG. 2 is an enlarged view of the area surrounded by the dotted line in FIG. 1( c ) in yet another embodiment of the first embodiment. This is a graph showing the results (after 24 hours) of antiviral test (1) of the coating film against the new coronavirus (COVID-19). This is a graph showing the results (after 24 hours) of antiviral test (2) of the coating film against the new coronavirus (COVID-19). 1 is a graph showing the results of an antiviral test of a coating film against influenza virus (after 24 hours). 1 is a graph showing the results (over time) of an antiviral test of a coating film against influenza virus. 1 is a graph showing the results of an antibacterial test of a coating film against Staphylococcus aureus (after 24 hours). 1 is a graph showing the results of an antibacterial test of the coating film against Escherichia coli (after 24 hours). 5( a ) to 5 ( c ) are cross-sectional views showing in time series the mechanism by which a coating film is formed on an article in Example 2. FIG. 12( c ) is an enlarged view of the area surrounded by the dotted line in FIG. FIG. 12( c ) is an enlarged view of the area surrounded by the dotted line in another embodiment of the second embodiment. 1A and 1B are images of the surface of a metal material coated with a coating film, taken by AFM measurement; FIG. 1A shows a surface coated with one coating film, and FIG. 1B shows a surface coated with three coating films. 1 is a table showing the results of an ATP wipe test.

The following describes the embodiments of the coating material and coating method according to the present invention.

The embodiment of the coating material and coating method according to the first embodiment of the present invention will be described below with reference to Figs. 1 to 11.

(Coating Liquid)
The coating liquid 110 as the coating material of the present invention is mainly composed of a base agent 110A and an additive 110B added to the base agent 110A. First, the base agent 110A contains at least an inorganic or organic polysilazane and an alkyl silicate condensate as raw materials, and in this Example 1, the inorganic or organic polysilazane and the alkyl silicate condensate are diluted with an inert solvent.

When inorganic polysilazane is used as the raw material for base agent 110A, the inorganic polysilazane and alkyl silicate condensate are dissolved in dibutyl ether as an inert solvent in this Example 1 at a concentration of 10 to 80 mass % in total, more preferably at a concentration of 50 to 80 mass %. More specifically, the inorganic polysilazane is contained at 0.1 to 5 mass %, with the remainder being alkyl silicate condensate.

More specifically, inorganic polysilazane is a perhydropolysilazane, that is, an inorganic polymer having a chain structure composed of Si-H bonds, Si-N bonds, and N-H bonds, for example, -(SiH2-NH)- units represented by the following general formula (1).

In addition, inorganic polysilazanes are not limited to those having a chain structure, and may be polymers having a cyclic structure, or may be polymers having a combination of these structures.

When organic polysilazane is used as the raw material for base agent 110A, the organic polysilazane and alkyl silicate condensate are dissolved in dibutyl ether as an inert solvent in Example 1 at a concentration of 1 to 80% by mass in total. More specifically, the organic polysilazane is contained at 0.1 to 80% by mass, with the remainder being alkyl silicate condensate.

More specifically, organic polysilazane is a polymer that has Si-N bonds and functional groups (R1 to R3) and is composed of -(SiR1R2-NR3)- units represented by the following general formula (2), and in particular, it is an organic polymer in which at least one of the functional groups R1 and R2 that are directly bonded to Si is composed of an organic functional group such as an alkyl group having carbon (C).

The organic polysilazane in this Example 1 is configured so that the content of methyl groups (CH3) as functional groups (R1 to R3) is 50% or more. The organic polysilazane is not limited to a polymer composed of one type of -(SiR1R2-NR3)- unit, but may be a polymer composed of multiple types of -(SiR1R2-NR3)- units with different compositions of functional groups (R1 to R3). The organic polysilazane may be a polymer having a chain, cyclic, or crosslinked structure, or may be a polymer having a combination of these structures.

More specifically, the organic polysilazane in this Example 1 is, for example, a polymer containing -(SiH(CH3)-NH)- units, -(Si(CH3)2-NH)- units, and -(SiR1(CH3)-NR3)- units, which are represented by the following general formula (3). In particular, the functional group R1 in the -(SiR1(CH3)-NR3)- unit is H or CH3, and the functional group R3 that is directly bonded to N is an organic functional group that promotes the reaction.

Furthermore, the organic polysilazane contained in the base agent 110A may be a mixture of multiple types of organic polysilazanes having different polymer structures, for example, multiple types of organic polysilazanes represented by the above general formula (3) or organic polysilazanes having other structures may be mixed. For example, in this embodiment 1, at least one type selected from hexamethyldisilazane, octamethylcyclotetrasilazane, or tetramethyldisilazane may be used.

The alkyl silicate condensate is, for example, a condensate of one or more of the following: tetramethyl orthosilicate, tetraethyl orthosilicate, tetra-n-propyl orthosilicate, tetra-i-propyl orthosilicate, tetra-n-butyl orthosilicate, tetra-sec-butyl orthosilicate, methyl polysilicate, and ethyl polysilicate.

The inert solvent is a solvent inert to inorganic or organic polysilazane and alkyl silicate condensate, and is preferably selected from dibutyl ether, dimethyl ether, diethyl ether, dipropyl ether, turpentine oil, benzene, toluene, etc.

Additive 110B is added to base agent 110A described above, and as described below, 0.1 to 20 mass% of organic antiviral agent X (hereinafter simply referred to as organic antiviral agent X) containing particles 121 with a particle size of approximately 100 nm and 0.1 to 20 mass% of organic antiviral agent Y (hereinafter simply referred to as organic antiviral agent Y) containing particles 122 with a particle size of approximately 1 μm are added. The organic antiviral agents X and Y are more preferably added in an amount of 0.1 to 10 mass%. Furthermore, in this embodiment 1, an embodiment in which only organic antiviral agent X and organic antiviral agent Y are added will be described, but in addition to these, for example, an inorganic antiviral agent or an inorganic or organic antibacterial agent may also be added.

More specifically, organic antiviral agent X and organic antiviral agent Y contain at least diiodomethyl-paratolylsulfone as an active ingredient. The compositions of the active ingredients of organic antiviral agent X and organic antiviral agent Y are partially different. Organic antiviral agent X is a deep yellow transparent particle 121 containing the active ingredient dissolved in an inert solvent, and the particles 121 containing the active ingredient dispersed in the inert solvent have a particle size of approximately 100 nm. Particles 122 of organic antiviral agent Y are off-white in color and have a particle size of approximately 1 μm.

Also, depending on the type and mixing method of the inert solvent constituting the coating liquid 110, the particles 121, 122 of the organic antiviral agents X, Y may be dispersed in the inert solvent with the above-mentioned nano-level or micro-level particle size (100 nm to 1 μm), or may be dispersed in the inert solvent of the coating liquid 110 with a nano-level particle size (5 to 15 nm) smaller than the above-mentioned particle size. It goes without saying that the inert solvent constituting the coating liquid 110 is a solvent that is inactive not only to organic antiviral agents, but also to inorganic antiviral agents and inorganic or organic antibacterial agents.

(Embodiments of Coating Material)
The coating liquid 110 in this embodiment 1 is used as a predetermined amount of liquid sealed in a container made of, for example, glass or resin, and the liquid is moistened onto a fabric material (not shown) and applied to the surface of various objects to be coated to form a coating film. Note that the use of the coating material is not limited to this, and for example, a nonwoven fabric or the like that has been soaked in the coating liquid in advance may be sealed in a bag, and the bag may be opened when used, or the coating liquid may be sprayed in a mist-like manner onto the surface of the object to be coated to coat it.

(Method of applying coating film)
The coating liquid 110 is applied or sprayed onto the surface 102 of the article 101 to be coated, and chemically reacts with moisture to form a single-layer or multi-layer thin coating film 115, 135, 145. The coating films 115, 135, 145 are preferably layered to a thickness of 10 μm or less, more preferably 5 nm to 5 μm.

First, a sterilization process is performed to sterilize the surface 102 of the article 101 prior to the coating process of the coating films 115, 135, and 145. In this sterilization process, a sterilization liquid in which hypochlorous acid or sodium hypochlorite, which has antibacterial and antiviral effects in addition to sterilization effects, is applied to the surface 102 of the article 101 using a spray bottle or a nonwoven fabric impregnated with the sterilization liquid. By sterilizing in this manner, it is possible to produce high-quality, highly durable coating films 115, 135, and 145 that are easy to apply to the surface 102 of the article 101 in a clean state and that are difficult to peel off.

In addition, after the above-mentioned sterilization process and before the coating process, water (H2O) such as purified water may be applied to the surface 102 of the article 101 using a nonwoven fabric or a spray bottle as a pre-process. This promotes a chemical reaction between the water applied to the surface 102 of the article 101 and the components contained in the coating liquid 110, and allows the coating film 115, 135, 145 to be rapidly and firmly formed on the surface 102 of the article 101.

(Object to be coated)
The object to be covered may be various articles made of materials such as resin, metal, wood, rubber, leather, etc., or may be a fixed object such as a fixture, and examples of suitable objects to be covered include the operating surface of a mobile terminal or remote control, the top or drawer of a desk or table, tableware, hand-held items such as bags and wallets, construction and temporary materials, etc., which are frequently touched by multiple people. In particular, in recent years, taking into maximum consideration the impact of the new coronavirus (COVID-19), items that are frequently touched by an unspecified number of people, such as fixtures, doorknobs, handrails, etc., installed in public institutions such as government offices, offices, commercial facilities, hospitals, schools, nursing homes, etc., or straps and handrails on public transportation such as trains and buses, are more suitable objects to be covered.

(Mechanism of coating film formation)
Next, the mechanism by which the coating films 115, 135, and 145 according to the present invention are formed will be described. Note that, here, the case where inorganic polysilazane is used as the raw material of the base agent 110A constituting the coating liquid 110 will be described as an example. Also, Fig. 1 shows the mechanism by which the coating film 115 is formed, but the mechanism by which the coating films 135 and 145 (see Figs. 4 and 5), which are another embodiment of this Example 1, are formed is also substantially the same as Fig. 1, so the explanation of the mechanism by the figures for the other embodiment will be omitted.

As shown in FIG. 1(a), the surface 102 of an object 101 to be coated, for example made of a metal material, often has a number of moisture 106, 106, ... (water droplets) attached thereto due to condensation or moisture in the air, even if only slightly. When the surface 102 of this object 101 is coated with a coating liquid 110 by applying or spraying it in a thin film, the inorganic polysilazane perhydropolysilazane constituting the base agent 110A contained in the coating liquid 110 reacts chemically with moisture (H2O) in the air to produce a coating layer having an inorganic structure mainly composed of SiO2 on the surface 102 of the object 101. Note that the above-mentioned chemical reaction produces a small amount of gas (NH3, H2) as a by-product, but of course these gases do not remain on the surface 102 of the object 101 but volatilize into the atmosphere.

That is, as shown in FIG. 1(b), the coating liquid 110 chemically reacts with the moisture contained in the air at the surface 110a in contact with the air, causing gases such as hydrogen and ammonia, which are by-products of the coating film 115, to evaporate from the surface, and a coating layer 111 is produced on the surface side of the coating film 115.

The coating liquid 110 coated on the surface 102 of the article 101 reacts chemically with the moisture 106, 106, ... (water droplets) attached to the surface 102 or the hydroxyl groups -OH present as terminals on the surface 102 at the back surface 110b in contact with the surface 102 of the article 101, causing gases such as hydrogen and ammonia to rise within the coating layer and volatilize from the surface, and a coating layer 112 is generated on the back side of the coating film 115.

In this way, coating layers 111 and 112 are first generated on the surface surface 110a and the back surface 110b of the coating liquid 110, respectively. Next, intermediate coating layers are generated by spreading the coating layer 111 from the surface side toward the back surface, and spreading the coating layer 112 from the back surface toward the surface side, and finally a coating film 115 mainly composed of SiO2 is generated on the surface surface 114a in contact with the outside air and the back surface 114b in contact with the surface 102 of the article 101. In this way, the coating films 115, 135, and 145 of the present invention are mainly composed of SiO2 generated by reacting inorganic or organic polysilazane, and can form a coating layer that is easy to spread in a plane and has a high density, thereby achieving a nano-level thin film structure.

As shown in FIG. 1(c) and FIGS. 2, 4, and 5, the surface 102 of the article 101 before being coated with the coating films 115, 135, and 145 has many microscopic irregularities 103 formed due to small scratches and the like that occur during the manufacturing process, etc., unless a special surface treatment such as mirror finishing is performed. The coating liquid 110 covers the surface 102 of the article 101 and hardens as described above while penetrating into the irregularities 103, so that a part of the coating film that has hardened and penetrated into these irregularities 103 functions as an anchor portion 117 (see FIGS. 2, 4, and 5), and the coating films 115, 135, and 145 adhere more firmly to the surface 102 of the article 101.

As shown in Figures 2 to 5, the additive 110B contained in the coating liquid 110, i.e., the organic antiviral agent particles 121 and 122, are mixed in the layers of the coating films 115, 135, and 145 as numerous nano- or micro-level fine particles as described above, and a portion of the surface is exposed on the surface 114a as described below.

The coating films 115, 135, and 145 of the present invention are formed into nano-level thin films by using inorganic polysilazane as the raw material for the base agent 110A, and specifically, have a film thickness of about 5 to 500 nm. Therefore, even though the coating film is mainly composed of SiO2, it is highly flexible, and coupled with the anchor effect of the anchor portion 117 described above, the coating films 115, 135, and 145 can maintain their coverage by following the deformation of the surface 102 of the article 101 without peeling off, even if the surface 102 is a cloth material or the like that undergoes deformation.

The present embodiment 1 shown in Figs. 2 and 3 differs from the other embodiment shown in Fig. 4 and the further embodiment shown in Fig. 5 in the thickness of the coating film and the particle diameter of the organic antiviral agent contained in the coating film. More specifically, the coating film 115 shown in Figs. 2 and 3 is formed to a thickness of approximately 100 nm, and the organic antiviral agent particles 121, 122 are mixed in the form of fine particles with a diameter of 5 to 15 nm. The coating film 135 of the other embodiment shown in Fig. 4 is formed to a thickness of approximately 100 nm, and the organic antiviral agent particles 121, 122 are mixed in the form of fine particles with a diameter of 100 nm to 1 μm. The coating film 145 of the further embodiment shown in Fig. 5 is formed to a thickness of approximately 500 nm, and the organic antiviral agent particles 121, 122 are mixed in the form of fine particles with a diameter of 100 nm to 1 μm.

When the surface 102 of the article 101 is a smooth surface that has almost no unevenness 103, the surface 102 of the article 101 may be roughened with a file or the like as a pretreatment before coating the coating film 115, 135, 145, thereby intentionally creating unevenness 103 or relatively rough unevenness 104 on the surface 102 of the article 101. In this way, the anchor effect of the coating film 115, 135, 145 can be obtained.

By carrying out this roughening process, it is preferable to form uneven portions 103, 104 with an arithmetic mean roughness in the range of about 0.1 to 1 μm on the surface 102 of the article 101, and this can enhance the anchoring effect of the coating films 115, 135, 145. In particular, as shown in Figures 4 and 5, when the organic antiviral agent particles 121, 122 are mixed in the form of relatively large particles with a maximum particle size of about 1 μm, by carrying out the roughening process to form the relatively coarse uneven portion 104 on the surface 102 of the article 101, the large particles 121, 122 can be held by the uneven portion 104. In other words, by carrying out the roughening process with an arithmetic mean roughness according to the particle size of the antiviral agent, the retention power of the antiviral agent can be increased.

After the roughening process, a cleaning process is performed using an air injection means such as an air gun to blow away metal powder that has been generated on the surface 102 of the item 101 by sanding, etc. Furthermore, after this cleaning process, a predetermined time is left to cause condensation, etc. to form on the surface 102 of the item 101, and naturally occurring moisture is attached to it.

In this case, after the surface 102 of the article 101 is roughened and cleaned, moisture may be actively applied to the surface 102 of the article 101 on which the uneven portions 103, 104 have been formed by roughening, using a moisture applying means such as a sprayer, as a pre-treatment step prior to the coating step, and then the surface 102 may be coated with the coating film 115, 135, 145. In this way, a chemical reaction between the moisture applied to the surface 102 of the article 101 and the coating liquid 110 in contact with the surface 102 of the article 101 can be promoted. Note that moisture may be applied to the surface 102 of the article 101 by a moisture applying means without performing a particular roughening treatment.

(Shape of the coating layer of the coating film)
1, the surface of the coating film 115, 135, 145 coated on the surface 102 of the article 101 has a nano-level uneven portion 116 formed on the surface 114a of the coating film 115, 135, 145 at the trace of the portion where the by-product gas bubbles have evaporated. More specifically, it is assumed that a large number of bubbles of hydrogen, ammonia, etc. are generated by the above-mentioned chemical reaction, and when these bubbles are released into the air from the smooth surface 114a of the coating film 115, 135, 145, the influence of the surface tension generated on the surface 114a of the coating film 115, 135, 145 in contact with the bubbles and the influence of the timing of the initial hardening of the surface 114a due to the chemical reaction combine to generate the uneven portion 116 consisting of nano-level recesses 116b and protrusions 116a on the smooth surface. 1 to 3, the unevenness dimensions of the uneven portion 116 are shown exaggerated from the actual size, and the uneven portion 116 is omitted in FIGS.

In addition, the unevenness 116 formed on the surface of the coating film 115, 135, 145 has smaller depth and height dimensions than the unevenness 103 initially formed on the surface 102 of the article 101 before coating, so by coating the surface 102 of the article 101 with the coating film 115, 135, 145, the surface is generated smoother after coating than before coating.

Needless to say, the above-mentioned by-product gas is generated uniformly on the surface of the coating film 115, 135, 145, so the uneven portion 116 is formed uniformly without variation in the number per unit area of the coating film 115, 135, 145, the depth of the recesses, or the height of the protrusions.

Furthermore, as shown in Figures 2 to 5, additive 110B, i.e., organic antiviral agent particles 121 and 122, which are mixed in the form of fine particles in coating films 115, 135, and 145, are fixed on surface 114a with a portion of the surface exposed to the outside.

More specifically, as described above, perhydropolysilazane constituting the base agent 110A of the coating liquid 110 reacts chemically with moisture (H2O) to generate secondary gases (NH3, H2), and these gases rise accompanied by the surrounding organic antiviral agent particles 121, 122 in the coating liquid 110. Therefore, as shown particularly in FIG. 2, some of the organic antiviral agent particles 121, 122 in the coating liquid 110 gather near the surface 114a of the coating film 115, and in particular gather at the uneven portion 16 formed on the surface 114a by the evaporation of the gas.

As shown in Figures 2 and 3, some of the organic antiviral agent particles 121, 122 are arranged on the surface 114a so as to complement the concave shape of the recess 116b. In this way, the organic antiviral agent particles 121, 122 act directly on various viruses, allowing a high antiviral effect to be maintained for a long period of time. In addition, the recess 116b is partially filled with the organic antiviral agent particles 121, 122, which increases the smoothness of the surface 114a.

In addition, another part of the organic antiviral agent particles 121, 122 (only particle 121 is shown in FIG. 3) is disposed on the surface surface 114a so as to be embedded inside the coating film 115, but a groove 116e is formed in the organic antiviral agent particles 121, 122, which extends from the surface of the particles 121, 122 to the surface surface 114a due to the evaporation of gas, and a part of the surface of the particles 121, 122 is exposed to the outside through the groove 116e. In this way, the organic antiviral agent particles 121, 122 embedded on the surface surface 114a side can also directly act on various viruses, and a high antiviral effect can be maintained for a long time. As shown in FIG. 3, the groove 116e is formed deeper in the vertical direction than the particle diameter of the particle 121, and the particle 121 is in a stable state in which the entire particle is immersed in the groove 116e and a part of the surface is exposed to the outside, so that the antiviral effect can be maintained for a long time.

2, another part of the organic antiviral agent particles 121, 122 is disposed on the surface 114a so as to be embedded inside the protrusions 116a. In this way, when the protrusions 116a that form a protruding shape on the surface 114a of the coating film 115 are partially scraped off as the coated article 101 is used, the organic antiviral agent particles 121, 122 embedded in the protrusions 116a are exposed to the surface, so that a high antiviral effect can be maintained for a long period of time.

In addition, the coating liquid 110 uses inorganic polysilazane as a raw material for the base agent 110A, and an organic antiviral agent having a relatively low affinity with the base agent 110A is used, so that the base agent 110A is less likely to adhere to the surfaces of the organic antiviral agent particles 121, 122 due to the influence of surface tension generated on the surface layer 114a of the coating films 115, 135, 145. As a result, as shown in FIG. 3 in particular, a large gap S is formed between the surfaces of the organic antiviral agent particles 121, 122 and the separation portion 116c formed in the surface layer 114a, recess 116b, and groove portion 116e of the coating film 115, and the exposed portion of the organic antiviral agent particles 121, 122 can be secured on the surface layer 114a of the coating film 115 in a larger amount. In addition, a portion of the coating film that has hardened while penetrating into the unevenness of the surface of the organic antiviral agent particles 121, 122 functions as an anchor portion 116d on the back surface 114b side, and the organic antiviral agent particles 121, 122 can be stably fixed to the surface surface 114a of the coating film 115.

As another embodiment, the coating film 135 shown in FIG. 4 is formed to a thickness of approximately 100 nm, like the coating film 115 described above, whereas the particle diameters of the organic antiviral agent particles 121 and 122 are 100 nm to 1 μm, the organic antiviral agent particles 121 are approximately the same size as the coating film 135, and the organic antiviral agent particles 122 are larger than the coating film 135. Therefore, the upper portions of these particles 121 and 122 are exposed to the outside of the surface 114a of the coating film 135. In this way, the organic antiviral agent particles 121 and 122 can directly act on various viruses, and a high antiviral effect can be maintained for a long period of time. In particular, some of the organic antiviral agent particles 122 have a particle size of about 1 μm, which corresponds to a few times, and up to about 10 times, the thickness of the coating film 135, which is about 100 nm. Therefore, most of the particles 122 are exposed to the outside of the surface 114a of the coating film 135, and a higher antiviral effect can be achieved.

Furthermore, some of the organic antiviral agent particles 121, 122 have their lower portions fitted into the uneven portions 103 formed on the surface 102 when the coating liquid 110 is applied, and the base agent 110A hardens in this state, so that the antiviral effect can be maintained for a long period of time without peeling off.

In addition, the coating film 145 shown in FIG. 5 as another embodiment is formed to have a thickness of approximately 500 nm, which is larger than the coating film 115 described above, whereas the particle diameters of the organic antiviral agent particles 121 and 122 are 100 nm to 1 μm, the organic antiviral agent particles 121 are smaller than the thickness of the coating film 135, and the organic antiviral agent particles 122 are larger than the thickness of the coating film 135. Therefore, some of the organic antiviral agent particles 121 in the coating liquid 110 gather near the surface 114a of the coating film 145, and are exposed together with the organic antiviral agent particles 122 so that their upper parts are exposed to the outside of the surface 114a of the coating film 145. In this way, these organic antiviral agent particles 121 and 122 can directly act on various viruses, and a high antiviral effect can be maintained for a long time. In particular, some of the organic antiviral agent particles 122 have a particle size of about 1 μm, which is equivalent to about twice the thickness of the coating film 145, which is about 500 nm, so that roughly half of the particles 122 are exposed to the outside of the surface 114a of the coating film 145, and a higher antiviral effect can be achieved.

As for the coating films 135, 145 shown in Figs. 4 and 5, similarly to the coating film 115 shown in Figs. 2 and 3, the surface tension generated on the surface layer 114a of the coating films 135, 145 can ensure a larger exposed portion of the organic antiviral agent particles 121, 122, and a part of the coating film that hardens while penetrating into the unevenness of the surface of the organic antiviral agent particles 121, 122 functions as an anchor portion 116d on the back layer surface 114b side, so that the organic antiviral agent particles 121, 122 can be stably fixed to the coating films 135, 145.

The following various evaluation tests of the coating film according to the present invention were conducted on the material coated with the above-mentioned coating film 115.

(Method for evaluating antiviral effects (Novel Coronavirus (1)))
To evaluate the antiviral effect of the coating film against the new coronavirus (COVID-19), 0.4 ml of the new coronavirus virus liquid was dropped onto the surface of a 5 cm square polyvinyl chloride (PVC) test piece (with and without a coating film), and the surface of the test piece was covered with a 4 cm square film and left to stand at 25°C for 24 hours. The virus on the test piece was washed out and collected, and then the virus infectivity (residual virus rate) was measured by the plaque measurement method. In addition, measurements were performed on three samples each, and the antiviral activity value was calculated using the following formula.
R = Ut - At
R: Antiviral activity value Ut: Average common logarithm of the viral infectivity (PFU/cm2) of untreated products (without coating film) after standing for 24 hours At: Average common logarithm of the viral infectivity (PFU/cm2) of antiviral treated products (with coating film) after standing for 24 hours

(Evaluation of antiviral effect)
The results of the antiviral test (1) against the new coronavirus are shown in FIG. 6. As shown in FIG. 6, the virus reduction rate of the test piece not coated with the coating film (without the coating film) was 81.5% compared to before the test, whereas the virus reduction rate of the test piece coated with the coating film according to the present invention (with the coating film) was a high value of 94.45%, that is, it was confirmed that the coating film according to the present invention significantly reduces the residual virus rate of the new coronavirus. In addition, it was confirmed that the antiviral activity value R of the coating film according to the present invention was 0.52, that is, a virus reduction rate of 69.8% compared to without the coating film. This is presumably because, as shown in FIGS. 2 and 3, the particles 121, 122 containing the active ingredient of the organic antiviral agent fixed in an exposed state on the surface 114a of the coating film 115 directly contact the new coronavirus and act on it, destroying the envelope (outer shell) of the virus to kill it, thereby maintaining the surface 114a clean.

In ISO 21702, it is said that an antiviral effect is evaluated when the antiviral activity value R is 2.0 or more. However, it is speculated that the test piece with the coating film used in the above antiviral test (1) may not have been able to fully exert its antiviral effect due to the influence of handling during transportation to the overseas testing institute.

(Method for evaluating antiviral effects (Novel Coronavirus (2)))
Therefore, in order to eliminate the influence of handling during transportation, a testing institute in Japan evaluated the antiviral effect of the coating film against the new coronavirus (COVID-19). The antiviral effect was evaluated based on ISO21702:2019, using a method similar to the antiviral test (1) conducted by the overseas testing institute for the new coronavirus, in which the virus infectivity (residual virus rate) of the new coronavirus was measured and the antiviral activity value was calculated.

(Evaluation of antiviral effect)
The results of the antiviral test (2) against the new coronavirus are shown in FIG. 7. As shown in FIG. 7, the virus reduction rate of the test piece not coated with the coating film (without the coating film) was 74.3% compared to before the test, whereas the virus reduction rate of the test piece coated with the coating film according to the present invention (with the coating film) was a high value of 99.98%, that is, it was confirmed that the coating film according to the present invention significantly reduces the residual virus rate of the new coronavirus. In addition, the antiviral activity value R of the coating film according to the present invention was 3.0, that is, a virus reduction rate of 99.9% compared to without the coating film, and it was confirmed that it exhibits excellent antiviral effect against the new coronavirus. This is presumably because, as shown in FIGS. 2 and 3, the particles 121, 122 containing the active ingredient of the organic antiviral agent fixed in an exposed state on the surface 114a of the coating film 115 directly contact the new coronavirus and act on it, destroying the envelope (outer shell) of the virus to kill it, thereby maintaining the surface 114a clean.

As mentioned above, ISO21702 states that an antiviral activity value R of 2.0 or more is considered to be effective. However, the test piece with the coating film used in the above antiviral test (2) was precisely tested at a testing institute in Japan without being affected by transportation, etc., and showed an antiviral activity value R of 3.0, which suggests that the product exhibited a high level of antiviral effect.

(Method for evaluating antiviral effect (influenza A virus))
As a method for evaluating the antiviral effect of the coating film against influenza A virus (H3N2), the virus infectivity (residual virus rate) of influenza A virus was measured and the antiviral activity value was calculated in the same manner as in the test for the novel coronavirus, based on ISO 21702: 2019. In this test, the virus infectivity (residual virus rate) over time was also measured.

(Evaluation of antiviral effect)
The results of the antiviral test against influenza A virus are shown in Figures 8 and 9. As shown in Figure 8, the virus reduction rate of the test piece not coated with the coating film (without coating film) was 97.6% compared to before the test, whereas the virus reduction rate of the test piece coated with the coating film according to the present invention (with coating film) was a high value of 99.998%, which confirmed that the coating film according to the present invention significantly reduced the residual virus rate of influenza A virus. In addition, the antiviral activity value R of the coating film according to the present invention was 2.5, i.e., a virus reduction rate of 99.93% compared to without the coating film, and it was confirmed that the coating film exhibited excellent antiviral effects. This is presumably because, as shown in Figures 2 and 3, the particles 121 and 122 containing the active ingredient of the organic antiviral agent fixed in an exposed state on the surface 114a of the coating film 115 directly contact and act on influenza A virus, destroying the envelope (outer shell) of the virus to kill it, thereby maintaining the surface 114a clean.

In addition, based on the sustainability standards of the Japan Society of Antibacterial Products, a light resistance treatment (category 1) was performed as a pretreatment by irradiating a xenon arc lamp for 10 hours. The antiviral activity value was calculated using the same evaluation method as above. As a result, the antiviral activity value R of the coating film according to the present invention against influenza A virus was 3.1, that is, a virus reduction rate of 99.99% or more compared to the case without the coating film, and it was confirmed that the coating film exhibits excellent antiviral effects.

As shown in FIG. 9, the virus reduction rate of the test piece coated with the coating film of the present invention (with coating film) for influenza A virus compared to before the test was 41.1% 30 minutes after the start of the test, 78.1% after 1 hour, 91.1% after 3 hours, 95.2% after 5 hours, and 99.998% after 24 hours, confirming that the residual virus rate significantly decreased over time. In addition, the virus reduction rate was about 80-90% after 1 to 3 hours from the start of the test, indicating the immediate antiviral effect of the antiviral agent contained in the coating film of the present invention. Thus, according to the coating method of the present invention, a rapid virus reduction rate of approximately 80% after 1 hour, more than 90% after 3 hours, and more than 95% after 5 hours can be achieved.

(Method of evaluating antibacterial effect)
The antibacterial effect of the coating film was evaluated based on JIS Z 2801, antibacterial processed products - antibacterial test method, by dropping 0.4 ml of Staphylococcus aureus (NBRC 12732) and Escherichia coli (NBRC 3972) bacteria liquid onto the surface of a 5 cm square test piece (with and without coating film), covering the surface of the test piece with a 4 cm square film, leaving it at rest for 24 hours at 35°C ± 1°C and a relative humidity of 90% or more, washing out and recovering the bacteria on the test piece, and then measuring the viable cell count. Measurements were also performed on three samples each, and the antibacterial activity value was calculated using the same calculation method as the antiviral activity value described above.

(Evaluation of antibacterial effect)
The results of the antibacterial test against Staphylococcus aureus are shown in Figure 10. As shown in Figure 10, the viable cell reduction rate of the test piece not coated with the coating film (without coating film) was 45.0% compared to before the test, whereas the viable cell reduction rate of the test piece coated with the coating film according to the present invention (with coating film) was 99.99% or more, that is, it was confirmed that the viable cell count rate of Staphylococcus aureus was significantly reduced. In addition, the antibacterial activity value R of the coating film according to the present invention was 4.4, that is, the viable cell reduction rate was 99.99% compared to without the coating film, that is, the viable cell count rate after 24 hours was approximately 0 (zero), and it was confirmed that the coating film according to the present invention exhibited excellent antibacterial properties. This is presumably because, as shown in Figures 2 and 3, particles 121, 122 containing the active ingredient of an organic antiviral agent which are fixed in an exposed state on surface 114a of coating film 115 directly come into contact with Staphylococcus aureus and act to destroy the cell membrane of the bacteria, thereby killing the bacteria, thereby maintaining surface 114a clean.

In addition, based on the sustainability standards of the Japan Society of Antibacterial Product Technology, a light resistance treatment (category 1) was performed as a pretreatment by irradiating a xenon arc lamp for 10 hours. The antibacterial activity value was calculated using the same evaluation method as above. As a result, the antibacterial activity value R of the coating film according to the present invention against Staphylococcus aureus was 4.0, that is, a live bacteria reduction rate of 99.99% or more compared to the case without the coating film, and it was confirmed that the coating film exhibits excellent antibacterial effects.

The results of the antibacterial test against E. coli are shown in Figure 11. As shown in Figure 11, the viable cell count rate of the test piece not coated with the coating film (without coating film) increased by about 55 times compared to before the test, whereas the viable cell count rate of the test piece coated with the coating film according to the present invention (with coating film) was 99.999% or more, i.e., the viable cell count rate of E. coli was significantly reduced. In addition, the antibacterial activity value R of the coating film according to the present invention was 6.1, i.e., a viable cell count rate of 99.999% compared to without the coating film, i.e., the viable cell count rate after 24 hours was approximately 0 (zero), and it was confirmed that the coating film according to the present invention exhibits excellent antibacterial properties. As shown in Figures 2 and 3, it is presumed that the particles 121, 122 containing the active ingredient of the organic antiviral agent, which are fixed in an exposed state on the surface 114a of the coating film 115, come into direct contact with the E. coli bacteria and destroy the cell membrane of the bacteria, thereby killing them, thereby keeping the surface 114a clean.

In addition, based on the sustainability standards of the Japan Society of Antibacterial Product Technology, a light resistance treatment (category 1) was performed as a pretreatment by irradiating a xenon arc lamp for 10 hours. The antibacterial activity value was calculated using the same evaluation method as above. As a result, the antibacterial activity value R of the coating film according to the present invention against E. coli was 6.1, that is, a live bacteria reduction rate of 99.99% or more compared to when there was no coating film, and it was confirmed that it exhibits excellent antibacterial effect. In this way, it was confirmed that the particles 121 and 122 containing the active ingredient of the organic antiviral agent have a certain antibacterial effect in addition to the antiviral effect described above.

(Method A for evaluating antifungal effect)
As an evaluation method A of the antifungal effect of the coating film, based on JIS Z 2911:2018, test pieces (with and without coating film) were attached to an inorganic salt agar medium, and a mixed spore suspension of five strains (Aspergillus niger NBRC 105649, Penicillium pinophilum NBRC 100533, Paecilomyces variotii NBRC 107725, Trichoderma virens NBRC 6355, Chaetomium globosum NBRC 6347) was sprayed, and the mixture was cultured at 29±1°C and a relative humidity of 95% or more for 28 days. The growth of mold on the sample pieces was visually observed, and the results of evaluation of the mold growth and mold resistance display are shown in Table 1. Mold growth was evaluated as follows: no mold growth (-), mold growth observed under a microscope (±), and significant mold growth (+). Mold resistance was evaluated as follows: no mold growth observed with the naked eye or under a microscope (0), mold growth not observed with the naked eye but observed under a microscope (1), mold growth within 25% of the sample area (2), mold growth within 25-50% of the sample area (3), mold growth within 50-100% of the sample area (4), and hyphae growth was vigorous, covering the entire sample (5).

In addition, based on the sustainability standards of the Japan Society of Antibacterial Products, products were subjected to a water resistance treatment (category 1) in which the product was pretreated by immersing it in water at room temperature for 16 hours. The results of the evaluation of mold growth and mold resistance display were shown in Table 2 using the same evaluation method as above.

In addition, based on the sustainability standards of the Japan Society of Antibacterial Products, products were subjected to a pre-treatment of lightfastness (category 1) in which they were exposed to a xenon arc lamp for 10 hours. The results of the evaluation of mold growth and mold resistance were shown in Table 3 using the same evaluation method as above.

(Evaluation of Antifungal Effect (Method A))
As shown in Tables 1 to 3, the results of the antifungal test confirmed that the test pieces coated with the coating film according to the present invention (with coating film) inhibited the growth of mold and had excellent mold resistance, compared to the test pieces not coated with the coating film (without coating film). It was also confirmed that the coating film according to the present invention also had excellent light resistance. This is presumably because particles 121 and 122 containing the active ingredient of the organic antiviral agent, which are fixed in an exposed state on the surface 114a of the coating film 115 as shown in Figures 2 and 3, inhibit the growth of mold.

(Method B for evaluating antifungal effect)
In addition, as an evaluation method B of the antifungal effect of the coating film, based on JIS Z 2911:2018, test pieces (with and without coating film) were attached to a glucose/inorganic salt agar medium, a mixed spore suspension of the same five strains as in the above-mentioned method A was sprayed, and the mixture was cultured for 28 days at 29±1°C and a relative humidity of 95% or more, and the growth of mold on the sample pieces was visually observed, and the results of evaluation of the mold resistance indication are shown in Table 4. Evaluation was also performed on five samples of each type, and the mold resistance indication was evaluated using the same index as in the above-mentioned method A.

In addition, based on the sustainability standards of the Japan Society of Antibacterial Products, products that had been subjected to a water resistance treatment (category 1) in which they were pretreated by immersing them in water at room temperature for 16 hours were evaluated for mold resistance using the same evaluation method as above. The results are shown in Table 5.

In addition, based on the sustainability standards of the Japan Society of Antibacterial Products, products were subjected to a lightfast treatment (category 1) in which a xenon arc lamp was irradiated for 10 hours as a pretreatment, and the mold resistance rating was evaluated using the same evaluation method as above. The results are shown in Table 6.

(Evaluation of Antifungal Effect (Method B))
As shown in Tables 4 to 6, the results of the antifungal test confirmed that the test pieces coated with the coating film according to the present invention (with coating film) had superior mold resistance compared to the test pieces not coated with the coating film (without coating film). This is presumably because particles 121 and 122 containing the active ingredient of the organic antiviral agent, which are exposed and fixed on surface 114a of coating film 115 as shown in Figures 2 and 3, inhibit the growth of mold.

In this way, it has been confirmed that the particles 121, 122 containing the active ingredient of an organic antiviral agent fixed in an exposed state on the surface 114a of the coating film 115 according to the present invention have excellent antiviral effects, as well as antibacterial and antifungal effects, and are also excellent in water resistance and light resistance.

(Effects of the present invention)
As described above, the coating liquid 10 (coating material) of the present invention is prepared by adding an antiviral agent to a base agent, which is a coating agent in which polysilazane and an alkyl silicate condensate are dissolved in an inert solvent at a concentration of 50 to 80% by mass in total, at a ratio of 0.1 to 20% by mass, so that the antiviral agent is stably fixed to the surface layer of the glass coating film produced by polysilazane and the alkyl silicate condensate as a base material, with a large exposed area secured on the surface layer of the film, and the high antiviral effect of the object coated with this coating material can be maintained for a long period of time. For example, when an antiviral agent is kneaded into a resin product, most of the antiviral agent is buried inside, making it difficult to expose the antiviral agent on the surface, and there is a large loss of the antiviral agent added, but the antiviral agent is stably fixed to the surface layer of the glass coating film formed by the coating material of the present invention, with a large exposed area secured on the surface layer, so that a high antiviral effect can be achieved while reducing the amount of antiviral agent added.

In addition, by forming the coating film into a thin film with a thickness of 10 μm or less, an antiviral effect can be obtained by adding a small amount of antiviral agent to the base agent in the coating liquid at a ratio of 0.1 to 20 mass %, and the amount of antiviral agent added is small, reducing production costs.

In addition, because the polysilazane used as the base agent raw material is inorganic polysilazane, it is easy to form a thin glass coating film, making it easy to expose the antiviral agent on the surface of the film.

In addition, since the antiviral agent is an organic antiviral agent, the base agent is inorganic polysilazane, and by using an organic antiviral agent that has a relatively low affinity with the base agent, the base agent is less likely to adhere to the surface of the antiviral agent due to surface tension, and a larger exposed area of the antiviral agent can be secured on the surface layer of the glass coating film. In addition, the dispersibility of the antiviral agent in the coating liquid based on inorganic polysilazane is well maintained.

Furthermore, by using the antiviral agent, particularly the organic antiviral agent X, particles containing the active ingredient can be made into nano-level fine particles with a particle size of approximately 100 nm or less, and a high antiviral effect can be exerted against various viruses, including the novel coronavirus (COVID-19), which is 50 to 200 nm in size, and the influenza virus, which is 80 to 120 nm in size.

The coating liquid 10 (coating material) of the present invention may further contain an antibacterial agent at a ratio of 0.1 to 10% by mass in addition to the antiviral agent, thereby enhancing both the antibacterial and antiviral effects of the object to be coated.

The coating method of the present invention also includes a coating step in which a coating material is applied to the surface of an object to be coated, the coating material being prepared by adding an antiviral agent to a base agent in a ratio of 0.1 to 20% by mass of a coating agent that is a combination of polysilazane and an alkyl silicate condensate dissolved in an inert solvent at a concentration of 50 to 80% by mass in total. This produces a glass coating film of polysilazane and alkyl silicate condensate on the surface of the object to be coated, and the antiviral agent is stably fixed to the surface of the glass coating film as a base material while leaving a large exposed portion on the surface, thereby enabling the object to have a high antiviral effect over a long period of time.

The coating process is a process in which a thin layer of a coating film, which is a base material mainly composed of SiO2, is formed on the surface of the object to be coated, and an antiviral agent is exposed on the surface of the coating film. By exposing the antiviral agent on the surface of the coating film, the antiviral agent acts directly on various viruses, and a high antiviral effect can be maintained for a long period of time. Furthermore, by forming the coating film in a thin layer, it is possible to ensure compliance with the behavior of the surface of the object to be coated. Here, in the present invention, a thin layer means a film thickness at the micro- or nano-level of 10 μm or less, and more preferably a film thickness at the nano-level of less than 1 μm.

The coating process is a process in which a coating material is applied to the surface of the object to be coated that has moisture attached thereto, and a component contained in the coating material is caused to chemically react with the moisture attached to the surface of the object to be coated to produce a coating film that serves as a base material made of SiO2 on the surface of the object to be coated, and an antiviral agent is exposed in the recesses on the surface of the coating film that are formed by the chemical reaction, and the antiviral agent is exposed in the recesses on the surface of the coating film that are formed by the emission of gas produced by the chemical reaction between the component contained in the coating material and the moisture on the surface of the object to be coated. This antiviral agent acts directly on various viruses, allowing a high antiviral effect to be maintained for a long period of time.

The coating process is a process in which a coating material containing an antiviral agent, which is made of particles with a maximum diameter of 1 μm, is applied to the surface of the object to be coated to a thickness of 500 nm or less, which makes it easier to expose the antiviral agent on the surface of the coating film (see Figures 4 and 5 in particular).

In addition, by having a sterilization process in which the surface of the object to be coated is sterilized prior to the coating process, a high-quality, long-lasting coating film can be produced on the surface of the object to be coated that has been cleaned by the sterilization process.

In addition, by having a pretreatment process in which moisture is applied to the surface of the object to be coated prior to the coating process, the chemical reaction between the moisture and the components contained in the coating material is promoted by applying moisture to the surface of the object to be coated, and a coating film can be rapidly and firmly formed on the surface of the object to be coated.

In order to ensure that the antiviral agent is widely exposed on the surface of the glass coating film, it is preferable that the coating process be performed by applying multiple layers, such as applying two layers.

The embodiment for implementing the coating material and coating method according to the second embodiment of the present invention will be described below with reference to Figures 12 to 16.

(Coating Liquid)
The coating liquid 10 as the coating material of the present invention is mainly composed of a base agent 10A and an additive 10B added to the base agent 10A. First, the base agent 10A contains at least inorganic polysilazane and alkyl silicate condensate as raw materials, and in this Example 2, the inorganic polysilazane and the alkyl silicate condensate are diluted with an inert solvent.

The inorganic polysilazane and the alkyl silicate condensate are dissolved in dibutyl ether as an inert solvent in Example 2 at a concentration of 50 to 80% by mass in total. More specifically, the inorganic polysilazane is contained at 0.1 to 5% by mass, with the remainder being the alkyl silicate condensate.

More specifically, the inorganic polysilazane of this Example 2 is a perhydropolysilazane, that is, an inorganic polymer having a chain structure composed of Si-H bonds, Si-N bonds, and N-H bonds, for example, -(SiH2-NH)- units represented by the following general formula (1).

In addition, the inorganic polysilazane is not limited to those having a chain structure, but may be a polymer having a cyclic structure, or may be a polymer having a combination of these structures.

The alkyl silicate condensate is, for example, a condensate of one or more of the following: tetramethyl orthosilicate, tetraethyl orthosilicate, tetra-n-propyl orthosilicate, tetra-i-propyl orthosilicate, tetra-n-butyl orthosilicate, tetra-sec-butyl orthosilicate, methyl polysilicate, and ethyl polysilicate.

The inert solvent is a solvent inert to inorganic polysilazane and alkyl silicate condensate, and is preferably selected from dibutyl ether, dimethyl ether, diethyl ether, dipropyl ether, turpentine oil, benzene, toluene, etc.

Additive 10B is added to the above-mentioned base agent 10A, and contains 0.01 to 10 mass% of inorganic antibacterial agent 21, 0.01 to 40 mass% of inorganic antiviral agent 22, and 0.01 to 20 mass% of organic antibacterial/antiviral agent 23, more preferably 0.1 to 10 mass%.

More specifically, the inorganic antibacterial agent 21 contains silver oxide-zinc calcium phosphate (Ag2O-CaαZnβAlγ(PO4)6). The inorganic antiviral agent 22 contains at least a molybdenum compound or a silver compound. The organic antibacterial/antiviral agent 23 contains diiodomethyl-paratolylsulfone.

(Embodiments of Coating Material)
The coating liquid 10 of this embodiment 2 is used as a predetermined amount of liquid sealed in a container made of, for example, glass or resin, and the liquid is moistened onto a fabric material (not shown) and applied to the surface of various objects to be coated to form a coating film. Note that the use of the coating material is not limited to this, and for example, a nonwoven fabric or the like that has been soaked in the coating liquid in advance may be sealed in a bag, and the bag may be opened when used, or the coating liquid may be sprayed in a mist-like manner onto the surface of the object to be coated to cover it.

(Method of applying coating film)
The coating liquid 10 is applied or sprayed onto the surface 2 of the article 1 to be coated, and reacts chemically with moisture to form a single-layer or multiple-layer coating film 15, 35. The coating film 15 shown in Fig. 13 is layered at the micro level. The coating film 35 shown in Fig. 14 is layered at the nano level, and has a thickness of preferably 1 nm to 500 nm, and more preferably 5 nm to 200 nm.

First, a sterilization step is performed to sterilize the surface 2 of the article 1 prior to the coating step of the coating film 15, 35. In this sterilization step, a sterilization liquid in which hypochlorous acid or sodium hypochlorite, which has antibacterial and antiviral effects in addition to sterilization effects, is applied to the surface 2 of the article 1 using a spray bottle or a nonwoven fabric impregnated with the sterilization liquid. By sterilizing in this manner, it is possible to produce a high-quality, long-lasting coating film 15, 35 that is easy to apply to the surface 2 of the article 1 in a clean state and is difficult to peel off.

In addition, after the above-mentioned sterilization process and before the coating process, water (H2O) such as purified water may be applied to the surface 2 of the article 1 using a nonwoven fabric or a spray bottle as a pre-process. This promotes a chemical reaction between the water applied to the surface 2 of the article 1 and the components contained in the coating liquid 10, and allows the coating film 15, 35 to be rapidly and firmly formed on the surface 2 of the article 1.

(Object to be coated)
The objects to be coated can be various kinds of articles made of materials such as resin, metal, wood, rubber, leather, etc., or they can be fixed objects such as fixtures. Suitable objects to be coated include, for example, the surfaces of the operation parts of mobile terminals and remote controls, desk and table tops and drawers, tableware, portable items such as bags and wallets, doorknobs and handrails, hanging straps on trains and buses, and construction and temporary materials, which are objects that are likely to come into contact with multiple people.

(Mechanism of coating film formation)
Next, the mechanism by which the coating film 15, 35 according to the present invention is formed will be described. As shown in Fig. 12(a), in many cases, a surface 2 of an object 1 made of, for example, a metal material as a coating target has a number of moisture 6, 6, ... (water droplets) attached thereto, even if only slightly, due to condensation or moisture in the air. When the coating liquid 10 is applied or sprayed in a thin film form to cover the surface 2 of this object 1, perhydropolysilazane, which is an inorganic polysilazane constituting the base agent 10A contained in the coating liquid 10, chemically reacts with moisture (H2O) in the air, thereby generating a coating layer having an inorganic structure on the surface 2 of the object 1. Note that, although a small amount of gas (NH3, H2) is generated as a by-product of the above-mentioned chemical reaction, these gases naturally volatilize into the atmosphere without remaining on the surface 2 of the object 1.

That is, as shown in FIG. 12(b), the coating liquid 10 chemically reacts with the moisture contained in the air at the surface 10a in contact with the air, causing gases such as hydrogen and ammonia, which are by-products of the coating film 15, 35, to evaporate from the surface, and a coating layer 11 is produced on the surface side of the coating film 15, 35.

The coating liquid 10 coated on the surface 2 of the article 1 reacts chemically with the water 6, 6, ... (water droplets) attached to the surface 2 or the hydroxyl groups -OH present as terminals on the surface 2 at the back surface 10b in contact with the surface 2 of the article 1, causing gases such as hydrogen and ammonia to rise within the coating layer and volatilize from the surface, and a coating layer 12 is generated on the back side of the coating film 15, 35.

In this way, coating layers 11 and 12 are first generated on the surface surface 10a and the back surface 10b of the coating liquid 10, respectively. Next, coating layer 11 is spread from the surface side toward the back surface, and coating layer 12 is spread from the back surface toward the surface side, thereby successively generating intermediate coating layers, and finally coating films 15 and 35 are generated that span the surface surface 14a in contact with the outside air and the back surface 14b in contact with the surface 2 of the article 1.

As shown in FIG. 12(c), the surface 2 of the article 1 before being coated with the coating films 15, 35 has many microscopic irregularities 3 formed due to small scratches that occur during the manufacturing process, etc., unless a special surface treatment such as mirror finishing is performed. The coating liquid 10 hardens as described above while covering the surface 2 of the article 1 and penetrating into the irregularities 3, and the hardened coating material that has penetrated into these irregularities 3 functions as anchor portions 17, so that the coating films 15, 35 adhere more firmly to the surface 2 of the article 1.

As shown in Figures 13 and 14, the additives 10B contained in the coating liquid 10, i.e., the inorganic antibacterial agent 21, the inorganic antiviral agent 22, and the organic antibacterial and antiviral agent 23, are mixed in the form of numerous micro-level particles on the surface and inside of the coating film 15, 35, some of which are exposed on the surface 14a as described below.

The coating film 15 shown in FIG. 13 is formed at the micro level. Another embodiment, the coating film 35 shown in FIG. 14, is formed at the nano level and is thinner than the coating film 15 described above. Therefore, even though it is a glass coating film, it is highly flexible, and coupled with the anchor effect of the anchor portion 17 described above, the coating film 35 can maintain its coverage by following the deformation of the surface 2 without peeling off, even if the surface 2 of the object to be coated is a cloth material or the like that undergoes deformation.

If the surface 2 of the article 1 is a smooth surface that has almost no unevenness 3 as described above, the surface 2 of the article 1 may be roughened with a file or the like as a pretreatment before being coated with the coating film 15, thereby actively creating unevenness 3 on the surface 2 of the article 1. In this way, the anchoring effect of the coating film 15 can be obtained.

By carrying out this roughening process, it is preferable to form an uneven portion 3 on the surface 2 of the article 1 with an arithmetic mean roughness in the range of about 0.1 to 1 μm, which can enhance the anchoring effect of the coating film 15.

After the roughening process, a cleaning process is performed in which metal powder generated on the surface 2 of the article 1 by sanding or the like is blown away using an air injection means such as an air gun. Furthermore, after this cleaning process, a predetermined time is left to cause condensation or the like to form on the surface 2 of the article 1, causing natural moisture to adhere to it.

In this case, after the surface 2 of the article 1 has been roughened and cleaned, moisture may be actively applied to the surface 2 of the article 1 on which the uneven portion 3 has been formed by roughening using a moisture applying means such as a sprayer as a pre-treatment step prior to the coating step, and the surface 2 may then be coated with the coating film 15. In this way, a chemical reaction between the moisture applied to the surface 2 of the article 1 and the coating liquid 10 in contact with the surface 2 of the article 1 can be promoted. Note that moisture may be applied to the surface 2 of the article 1 using a moisture applying means without specifically performing a roughening treatment.

(Shape of the coating layer of the coating film)
As shown in Fig. 13, the surface of the coating film 15 coated on the surface 2 of the article 1 has a nano-level uneven portion 16 formed on the surface 14a of the coating film 15 at the traces of the places where the by-product gas bubbles have evaporated. More specifically, it is assumed that a large number of bubbles of hydrogen, ammonia, etc. are generated by the above-mentioned chemical reaction, and when these bubbles are released into the air from the smooth surface 14a of the coating film 15, the influence of the surface tension generated on the surface 14a of the coating film 15 in contact with the bubbles and the influence of the timing of the initial hardening of the surface 14a due to the chemical reaction combine to generate the uneven portion 16 consisting of nano-level recesses 16b and protrusions 16a on the smooth surface. Note that the uneven dimensions of the uneven portion 16 are shown in a deformed manner compared to the actual size in Figs. 12 and 13, and the uneven portion 16 is omitted in Fig. 14.

In addition, the unevenness 16 formed on the surface of the coating film 15, 35 has smaller depth and height dimensions than the unevenness 3 initially formed on the surface 2 of the article 1 before coating, so by coating the surface 2 of the article 1 with the coating film 15, 35, the surface is generated smoother after coating than before coating.

Needless to say, the gas by-products described above are generated uniformly on the surface of the coating film 15, so the dimples 16 are formed uniformly without variation in the number per unit area of the coating film 15, the depth of the recesses, or the height of the protrusions.

In addition, when comparing the dimples 16 formed in the coating film 15, 35 applied to the surface 2 of the article 1 when a single layer is applied as shown in FIG. 15(a) with the dimples 26 formed in the coating film 15, 35 when multiple layers are applied as shown in FIG. 15(b), it has been confirmed that the dimples 26 when multiple layers are applied have smaller depth and height dimensions of the unevenness. This is presumably because the unevenness of the dimples 16 when a single layer is applied is leveled by applying the coating film multiple times, resulting in the formation of smoother dimples 26.

Furthermore, additive B, which is mixed in the form of fine particles in the coating film 15, 35, i.e., inorganic antibacterial agent 21, inorganic antiviral agent 22, and organic antibacterial and antiviral agent 23, is fixed on the surface 14a with a portion of the surface exposed to the outside.

More specifically, as described above, perhydropolysilazane, which constitutes the base agent 10A of the coating liquid 10, reacts with moisture (H2O) to generate secondary gases (NH3, H2), and these gases rise, carrying with them the fine particles of additive B around the coating liquid 10. Therefore, as shown in FIG. 13, some of the additive B in the coating liquid 10 gathers near the surface 14a of the coating film 15, and particularly gathers in the unevenness 16 formed on the surface 14a by the evaporation of the gas.

Some of the fine particles of additive B are arranged on the surface 14a so as to complement the concave shape of the recess 16b. In this way, the inorganic antibacterial agent 21, inorganic antiviral agent 22, and organic antibacterial and antiviral agent 23 act directly on various germs and viruses, enhancing the antibacterial and antiviral effects for a long period of time. In addition, the recess 16b is partially filled with additive B, which enhances the smoothness of the surface 14a.

In addition, another portion of the fine particles of additive B are disposed on the surface 14a so as to be embedded inside the protruding portions 16a. In this way, when the protruding portions 16a that form a protruding shape on the surface 14a of the coating film 15 are partially scraped off as the coated article 1 is used, the additive B embedded in the protruding portions 16a is exposed to the surface, so that the antibacterial and antiviral effects can be maintained for a long period of time.

The coating film 15, 35 formed on the surface 2 of the article 1 by applying the coating liquid 10 according to the present invention has an inorganic base, and the additives, the antibacterial agent 21 and the antiviral agent 22, are also inorganic, so they do not dissolve or vaporize into the substrate or outside, and can maintain their coating state for a long period of time without deterioration.

In addition, the coating film 35 shown in FIG. 14 as another embodiment is formed at the nano level, which is thinner than the coating film 15 described above, and more specifically, the thickness is about 1 to 500 nm. In contrast, the inorganic antibacterial agent 21 has a particle size of about 0.8 to 1 μm, the inorganic antiviral agent 22 has a particle size of about 3 μm, and the organic antibacterial and antiviral agent 23 has a particle size of about 1 μm, all of which are larger than the thickness of the coating film 35. Therefore, these particles are exposed so that their upper parts are exposed to the outside of the surface layer 34a of the coating film 35. In this way, the inorganic antibacterial agent 21, the inorganic antiviral agent 22, and the organic antibacterial and antiviral agent 23 act directly on various germs and viruses, and the antibacterial and antiviral effects can be enhanced for a long period of time. In addition, by forming the coating film 35 in a thin layer, it is possible to ensure compliance with the behavior of the surface 2 of the article 1 even if the surface 2 is flexible.

Furthermore, some particles of additive B have their lower parts fitted into the unevenness 3 formed on the surface 2 when the coating liquid 10 is applied, and the base agent A hardens in this state, so that the antibacterial and antiviral effects can be maintained for a long period of time without peeling off.

(Method for evaluating antibacterial and antiviral effects)
As a method for evaluating the antibacterial and antiviral effects of the coating film, ATP (adenosine triphosphate) wipe tests were performed over time on the surface 2 coated with the coating film 15, 35, and evaluation was performed based on the ATP value. Here, ATP is a chemical substance that exists as an energy source for all living organisms on Earth, and the presence of ATP can be confirmed as evidence that bacteria/viruses themselves or traces of bacteria/viruses are present there. In other words, the higher the value in the ATP wipe test, the higher the degree of contamination of the surface is evaluated (higher the risk of infection), and the lower the value in the ATP wipe test, the lower the degree of contamination of the surface is evaluated (lower the risk of infection).

The ATP wipe test will be explained. In this ATP wipe test, a glass test material (A) coated on the surface with the coating material according to the present invention, test materials (B) to (E) coated on the surface with different types of coating materials described below for comparison, and a test material (no mark) that is not coated with any coating material are exposed to a room temperature environment in the same laboratory, and ATP is wiped off the surface of each test material every day (every 24 hours) and the number of ATP detected is compared. Note that the laboratory is an environment where multiple people come and go, and therefore where bacteria and viruses can enter. When wiping off ATP from the surface, the tip of a cotton-swab-shaped detection wire is rubbed on the surface of the test material under certain conditions, and the tip is inserted into a dedicated ATP detector (not shown) to detect the value of ATP attached to the tip.

Test material (B) is coated with a coating material consisting only of base agent 10A, without the additive 10B contained in the coating liquid 10 according to the present invention. Next, test material (C) is coated with an inorganic glass coating material intended for sports equipment, etc. Test material (D) is coated with an inorganic glass coating material intended for mobile terminals, etc. Test material (E) is coated with an inorganic ceramic coating material.

(Evaluation of antibacterial and antiviral effects)
The ATP wipe test results are shown in Figure 16. The test material (A) coated with the coating material according to the present invention showed almost no increase in ATP over time, and was confirmed to have the highest antibacterial and antiviral effects compared to the other test materials. This is presumably because, as shown in Figures 13 and 14, the inorganic antibacterial agent 21, the inorganic antiviral agent 22, and the organic antibacterial and antiviral agent 23 fixed in an exposed state on the surface 14a of the coating film 15, 35 directly contact bacteria and viruses that fly in the outside air with droplets and dust and try to attach to the surface 14a, and act to prevent them from settling, thereby maintaining the surface 14a clean.

In addition, although ATP increased over time in the test material (B), the rate of increase was only slight. This is presumably because the inorganic antibacterial agent 21, inorganic antiviral agent 22, and organic antibacterial and antiviral agent 23 described above are not present, and the base agent 10A containing inorganic polysilazane forms the surface of the coating film into a smooth surface mainly composed of SiO2, i.e., the surface is smoother than the surface of the test material before coating, which prevents the establishment of bacteria and viruses to a certain extent.

Furthermore, in sample (C), ATP increased significantly over time, and the rate of increase was higher than in sample (B). This is presumably because, unlike sample (A) described above, the inorganic antibacterial or antiviral agent is not exposed on the surface of the coating film, and therefore the material has little resistance to bacteria or viruses.

Similarly, in sample (D) and sample (E), ATP increased significantly over time, and the rate of increase was higher than in sample (B). This is presumably because, like sample (C), the inorganic antibacterial or antiviral agent was not exposed on the surface of the coating film and was therefore unable to exert a resistant effect against bacteria or viruses.

(Effects of the present invention)
As described above, the coating liquid 10 (coating material) of the present invention is obtained by dissolving inorganic polysilazane and alkyl silicate condensate in an inert solvent at a concentration of 50 to 80% by mass in total as a base agent 10A, and adding inorganic antibacterial agent 21 and inorganic antiviral agent 22 at a ratio of 0.1 to 5% by mass to base agent 10A. As a result, the inorganic antibacterial agent 21 and inorganic antiviral agent 22 are fixed in a stable state to the surface surface 14a of coating film 15, 35 using a glass coating film produced by inorganic polysilazane and alkyl silicate condensate as a base material, and therefore the antibacterial effect and the antiviral effect of the article 1 (coated object) coated with this coating liquid 10 can be compatible for a long period of time.

The coating liquid 10 can further contain 0.1 to 10 mass % of an organic antibacterial/antiviral agent 23, thereby enhancing both the antibacterial and antiviral effects of the article 1.

In addition, the coating process of the coating liquid 10 involves coating the surface 2 of the article 1 to which moisture has adhered with the coating liquid 10, and chemically reacting the components contained in the coating liquid 10 with the moisture adhered to the surface 2 of the article 1 to produce a coating film 15, 35 on the surface 2 of the article 1 as a base material mainly composed of SiO2, and exposing the antibacterial agent 21 and the antiviral agent 22 to the recesses 16b on the surface surface 14a of the coating film 15, 35 formed by the chemical reaction, so that the antibacterial agent 21 and the antiviral agent 22 act directly on various germs and viruses, thereby enhancing the antibacterial and antiviral effects for a long period of time. Furthermore, by disposing particles of the antibacterial agent 21 and the antiviral agent 22 in the recesses 16b on the surface surface 14a of the coating film 15, 35, the recesses 16b can be filled, and therefore the smoothness of the surface surface 14a can be improved compared to a coating liquid consisting of only a base agent that does not contain additives.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

For example, in the first embodiment, it is sufficient that at least the organic antiviral agent X is added as the antiviral agent, and the organic antiviral agent Y does not have to be added. The organic antiviral agent X may be in liquid form or in powder form. Similarly, the organic antiviral agent Y may be in liquid form or in powder form.

In addition, in Example 2, the coating liquid 10 contains the inorganic antibacterial agent 21 and the inorganic antiviral agent 22, but this is not limited thereto. As long as one material has both antibacterial and antiviral effects, only that material may be added.

Although the above-mentioned Examples 1 and 2 describe the case where inorganic polysilazane is used as the base agent, organic polysilazane may also be used as the base agent. In this case, by controlling the film thickness to the nano level, preferably to a thin film of about 500 nm, it is possible to easily expose the antiviral agent on the surface layer of the coating film. Furthermore, by using organic polysilazane, it is easy to form a micro-level coating film that is thicker than the nano level.

In addition, in the above-mentioned Examples 1 and 2, the coating film is formed into a nano-level thin layer with a thickness of approximately 100 to 500 nm, but it may be formed into a micro-level thin layer with a thickness of 10 μm or less.

1. Article (object to be coated)
2 Surface 3 Uneven portion 6 Water 10 Coating liquid (coating material)
10A Base agent 10B Additive 11, 12 Coating layer 14a Surface surface 14b Back surface 15, 35 Coating film 16 Concave and convex portion 16a Convex portion 16b Concave portion 17 Anchor portion 21 Inorganic antibacterial agent 22 Inorganic antiviral agent 23 Organic antibacterial/antiviral agent 101 Article (object to be coated)
102 Surface 103 Uneven portion 106 Moisture 110 Coating liquid (coating material)
110A Base agent 110B Additives 111, 112 Coating layer 114a Surface surface 114b Back surface 115, 135, 145 Coating film 116 Uneven portion 116a Convex portion 116b Concave portion 116c Separated portion 116d Anchor portion 116e Groove portion 117 Anchor portions 121, 122 Particles (antiviral agent)
S Gap

Claims (10)

A coating material characterized by comprising a base agent in which polysilazane and an alkyl silicate condensate are dissolved in an inert solvent at a combined concentration of 50-80% by mass, and an antiviral agent is added to the base agent at a ratio of 0.1-20% by mass. The coating material according to claim 1, characterized in that the polysilazane is an inorganic polysilazane. The coating material according to claim 2, characterized in that the antiviral agent is an organic antiviral agent. The coating material according to any one of claims 1 to 3, further comprising an antibacterial agent added at a ratio of 0.1 to 10% by mass. A coating method characterized by having a coating step in which a surface of an object to be coated is coated with a coating material obtained by adding an antiviral agent to a base agent in a ratio of 0.1 to 20 mass%, the base agent being a coating agent in which polysilazane and an alkyl silicate condensate are dissolved in an inert solvent at a concentration of 50 to 80 mass% in total. The coating method according to claim 5, characterized in that the coating step is a step of forming a thin coating film, which serves as a base material mainly composed of _SiO2 , on the surface of the object to be coated, and exposing the antiviral agent on a surface of the coating film. 6. The coating method according to claim 5, wherein the coating step is a step of coating a surface of the object to be coated having moisture thereon with the coating material, and causing a component contained in the coating material to chemically react with the moisture adhering to the surface of the object to be coated, thereby producing a coating film serving as a base material containing _SiO2 as a main component on the surface of the object to be coated, and exposing the antiviral agent in recesses in a surface layer of the coating film formed by the chemical reaction. The coating method according to claim 6 or 7, characterized in that the coating process is a process of coating the surface of the object to be coated with the coating material containing the antiviral agent, which is made of particles having a maximum diameter of 1 μm, to a thickness of 500 nm or less. The coating method according to any one of claims 5 to 8, characterized in that it includes a sterilization step of sterilizing the surface of the object to be coated prior to the coating step. The coating method according to any one of claims 5 to 9, characterized in that it includes a pretreatment step of adhering moisture to the surface of the object to be coated prior to the coating step.

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