Antiviral material

Abstract

To improve an antivirus activity by enhancing contact property between antivirus component and virus while suppressing an amount of antivirus component.SOLUTION: An antivirus material comprises: a base material; and a front layer part for covering at least a part of the surface of the base material, and having a plurality of particulate projections containing antivirus component of a metal or a metal oxide, and two-dimensionally arranged along the surface of the base material. In the front layer part, a median value of a diameter of an outer peripheral shape of the projection when viewing each of the projections from the top is 1 μm or less, a density of the projections composing the front layer part is 0.0002 / nm2 or more, and a coverage rate of the front layer part on the base material is 20% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to antiviral materials. [Background technology]

[0002] Conventionally, various antiviral materials have been known that contain active ingredients with antiviral activity, such as copper compounds like metallic copper and copper oxide, or copper ions. For example, Patent Document 1 describes an antiviral material in which metallic copper nanoparticles are coated with fatty acids and / or ester compounds. Patent Document 2 describes an antiviral fiber spun from a polymer material containing active ingredients such as iodide or monovalent copper compounds. Patent Document 3 describes a rayon fiber incorporating copper oxide nanoparticles. Patent Document 4 describes an antiviral material in which powdered copper oxide particles that release copper ions are encapsulated in a polymer material so that a portion of these particles is exposed. Non-Patent Document 1 describes a configuration in which divalent copper ions are adsorbed onto cotton fibers and then reduced to support Cu2O particles on the surface of cotton fibers. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-64979 [Patent Document 2] Japanese Patent Publication No. 2013-49944 [Patent Document 3] Special Publication No. 2010-522833 [Patent Document 4] Japanese Patent Publication No. 2012-229424 [Non-patent literature]

[0004] [Non-Patent Document 1] A. Errokh et al., Carbohydrate Polymers 141, (2016)229-237 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when microparticles containing antiviral components are coated with other compounds, as in Patent Document 1, or when polymers containing antiviral components are spun, as in Patent Document 2, the antiviral components may be covered by the other compounds or polymers, hindering contact between the antiviral components and viruses, potentially making it difficult to obtain sufficient antiviral activity. Furthermore, even when antiviral component particles are incorporated into a resin material and protrude from the surface of the resin material, as in Patent Documents 3 and 4, if the antiviral components are micronized to ensure a sufficient surface area, the antiviral components tend to aggregate. Therefore, it was difficult to increase the density of antiviral component particles while suppressing the aggregation of antiviral component particles, thereby ensuring contact between the antiviral component particles and viruses and enhancing antiviral activity. Additionally, when copper oxide is supported on fibers by reducing copper ions adsorbed onto fibers, as in Non-Patent Document 1, it was difficult to increase the density of antiviral component particles to ensure contact between the antiviral components and viruses, potentially resulting in insufficient antiviral activity.

[0006] Another method involves slurrying antiviral component particles and coating them onto the substrate surface to obtain an antiviral material. In this case, even if the antiviral component particles aggregate, it may be possible to increase the surface area of ​​the antiviral component by increasing the amount of antiviral component coated, thereby enhancing its antiviral activity. However, increasing the amount of antiviral component coated can be difficult to implement due to increased environmental impact and increased costs. Therefore, there has been a need for a technology that can reduce the amount of antiviral component while increasing the contact between the antiviral component and the virus, thereby allowing the antiviral activity of the antiviral component to be fully exhibited. [Means for solving the problem]

[0007] This disclosure can be implemented in the following forms: (1) According to one embodiment of the present disclosure, an antiviral material is provided. The antiviral material comprises a substrate and a surface layer covering at least a portion of the surface of the substrate, the surface layer containing an antiviral component which is a metal or metal oxide and comprising a plurality of particulate protrusions arranged two-dimensionally along the surface of the substrate, wherein in the surface layer, the median diameter of the outer shape of each of the protrusions when viewed from above is 1 μm or less, and the density of the protrusions constituting the surface layer is 0.0002 particles / nm 2 The above conditions are met, and the coverage rate of the surface layer on the substrate is 20% or more. This form of antiviral material ensures contact between the antiviral component and the virus through the surface shape of the surface layer, thereby reducing the amount of antiviral component while fully utilizing its performance and achieving high antiviral activity. (2) In the above-described form of antiviral material, the antiviral component may be one or more of copper, silver, zinc, iron, and oxides thereof. Such a configuration can enhance the antiviral performance of the antiviral material. (3) In the above-described form of antiviral material, the antiviral component may be metallic copper. With such a configuration, the antiviral performance of the antiviral material can be further enhanced. In particular, when metallic copper is used as the antiviral component, the oxidation of metallic copper can be suppressed, thereby preventing a decrease in the performance of the antiviral material caused by the oxidation of metallic copper. (4) In the above-described form of antiviral material, the base material may be a polymer fiber. With this configuration, it is possible to obtain a polymer fiber with high antiviral activity while suppressing the amount of antiviral component. (5) In the above-described form of antiviral material, the polymer fiber may have a fiber diameter of 1 μm or less. With this configuration, even when using relatively thin polymer fibers with a fiber diameter of 1 μm or less, it is possible to obtain polymer fibers with high antiviral activity while suppressing the amount of antiviral component. (6) In the antiviral material of the above aspect, the plurality of protrusions constituting the surface layer portion may have a median diameter of the outer peripheral shape of 100 nm or less when each protrusion is viewed from above. With such a configuration, it becomes easy to enhance the antiviral performance of the antiviral material. (7) In the antiviral material of the above aspect, the density of the protrusions constituting the surface layer portion is 0.0005 pieces / nm 2 or more. With such a configuration, it becomes easy to enhance the antiviral performance of the antiviral material. (8) In the antiviral material of the above aspect, the coverage of the surface layer portion on the base material may be 40% or more. With such a configuration, it becomes easy to enhance the antiviral performance of the antiviral material. (9) In the antiviral material of the above aspect, the thickness of the surface layer portion in the normal direction of the base material may be 5 μm or less. With such a configuration, peeling of the surface layer portion from the base material can be suppressed, and an increase in manufacturing cost can be suppressed. (10) In the antiviral material of the above aspect, let the median diameter of the outer peripheral shape when the protrusion is viewed from above be the particle diameter Rp, set the virus diameter Rv to 20 nm, and calculate the collision cross-sectional area Scol using the following formulas (1) to (3), and the particle density Dp, which is the density of the protrusions, the value of the collision frequency Fcol obtained by multiplying the foregoing may be 0.5 or more. [Mathematical formula] [Mathematical formula] [Mathematical formula] With such a configuration, the performance of the antiviral component can be sufficiently exhibited, and higher antiviral activity can be obtained. The present disclosure can be implemented in various forms other than those described above, and can be implemented, for example, in the form of a method for producing an antiviral material, a method for inactivating viruses, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] [Figure 1] A perspective view schematically illustrating an outline of a configuration of an antiviral material. [Figure 2] An explanatory diagram showing a relationship among particle density, particle size, and virus size. [Figure 3] An explanatory diagram showing a relationship among collision frequency, inter-particle spacing coefficient, and particle diameter. [Figure 4] An explanatory diagram showing a relationship among collision frequency, inter-particle spacing coefficient, and particle diameter. [Figure 5] An explanatory diagram showing a relationship between collision frequency and particle density when Rv is 20 nm. [Figure 6] An explanatory diagram showing calculated values related to collision frequency in a surface layer portion. [Figure 7] An explanatory diagram showing an FE-SEM image of sample S1. [Figure 8] An explanatory diagram showing an FE-SEM image of sample S2. [Figure 9] An explanatory diagram showing an FE-SEM image of sample S3. [Figure 10] An explanatory diagram showing an FE-SEM image of sample S4. [Figure 11] An explanatory diagram showing XRD patterns of samples S1 to S4. [Figure 12] An explanatory diagram showing surface layer portions formed on a PP base material and a Si base material, respectively. [Figure 13] An explanatory diagram showing SEM observation images of samples S6 and S7. [Figure 14] An FE-SEM image of an antiviral material using a nonwoven fabric as a base material. [Figure 15] An explanatory diagram showing a state of image analysis of sample S1. [Figure 16] An explanatory diagram collectively showing measured values and the like of each sample. [Figure 17] An explanatory diagram showing results of evaluating antiviral properties against Qβ and Φ6. [Figure 18] An explanatory diagram summarizing the antiviral activity values ​​of samples S1-S5. [Figure 19] An explanatory diagram showing the results of investigating the antiviral activity level against Qβ. [Figure 20] An explanatory diagram showing the XRD pattern for evaluating resistance to oxidation. [Modes for carrying out the invention]

[0009] A. Composition of antiviral material: Figure 1 is a schematic perspective view showing the general structure of the antiviral material 10 of this embodiment. The antiviral material 10 comprises a base material 30 and a surface layer 20 that covers at least a portion of the surface of the base material 30.

[0010] The surface layer 20 contains an antiviral component which is a metal or metal oxide and comprises a plurality of particulate protrusions 25 arranged two-dimensionally along the surface of the substrate 30. That is, the surface layer 20 has a fine protrusion structure formed by the two-dimensionally arranged protrusions 25, and these protrusions 25 are exposed on the surface of the antiviral material 10. Here, the arrangement of the protrusions 25 two-dimensionally along the surface of the substrate 30 means that the particulate protrusions 25 are arranged in a single layer on the substrate 30 and the particles do not form a three-dimensional aggregated shape. The antiviral material 10 of this embodiment is characterized by the structure of the surface layer 20 as described above, but a layer may be formed between the surface layer 20 and the substrate 30, for example, consisting of an antiviral component that covers the surface of the substrate 30.

[0011] The particulate protrusions 25 constituting the surface layer 20 may, for example, be nearly spherical, cylindrical, or columnar with an irregular shape when viewed from above. Multiple protrusions 25 are arranged two-dimensionally on the base material 30, and it is sufficient that each protrusion 25 is distinguishable when the surface layer 20 is viewed from above.

[0012] The antiviral component contained in the particulate protrusions 25 constituting the surface layer 20 is not particularly limited as long as it is an antiviral component that is a metal or a metal oxide, and it is sufficient that it can form a structure in which the protrusions 25 are arranged in two dimensions. For example, the fact that metallic copper and copper oxide have antiviral activity is described in the aforementioned Patent Documents 1 to 4 and Non-Patent Document 1. Also, for example, the fact that silver oxide (Ag2O) has antiviral activity is described in M. Minoshima, et al., J. Hazard. Mater., 312 (2016) 1., the fact that zinc oxide (ZnO) has antiviral activity is described in SM El-Megharbel, et al., Coatings, 11 (2021) 388., and the fact that iron oxide has antiviral activity is described in R. Kumar, et al., Journal of Infection and Chemotherapy, 25 (2019) 325. Thus, various metals or metal oxides that have antiviral activity can be used as antiviral components. More specifically, the antiviral component having antiviral activity is preferably one or more of copper, silver, zinc, iron, and their oxides. Among these, metallic copper or copper oxide (Cu2O or CuO) is preferred, and metallic copper is particularly preferred. When metallic copper is used as the antiviral component, by adopting the form of the surface layer 20 of this embodiment, the oxidation of metallic copper can be suppressed, and the deterioration of the performance of the antiviral material 10 caused by the oxidation of metallic copper can be suppressed. Regardless of which antiviral component is used, high antiviral activity can be achieved by forming a surface layer 20 in which the protrusions 25 containing these antiviral components are arranged two-dimensionally.

[0013] It is desirable that the content of the antiviral component in the protrusions 25 be high, and it is even more desirable that the entire protrusions 25 be composed of a metal or metal oxide which is the antiviral component. By making the above antiviral component the main component of the surface layer of the protrusions 25, it becomes easier to obtain the effect of improved antiviral performance due to the surface layer 20 having a fine protrusion structure. In this specification, "main component" of a specific component means that the content of the specific component is 50% by mass or more. In this embodiment, high antiviral performance is achieved by exposing the protrusions 25 on the surface of the antiviral material 10, but if a sufficient amount of antiviral component is present on the surface of the surface layer 20 and the effect of improved antiviral activity due to the fine protrusion structure of the surface layer 20 is ensured, other components may also be present on the protrusions 25.

[0014] In the antiviral material 10 of this embodiment, high antiviral activity is achieved by setting parameters related to the size and arrangement of the protrusions 25 constituting the surface layer 20 within a specific range, thereby ensuring contact with viruses on the surface shape of the surface layer 20 having a fine protrusion structure.

[0015] Specifically, in the surface layer 20, the median diameter of the outer circumference of each protrusion 25 when viewed from above should be 1 μm or less. In the following explanation, the median diameter of the outer circumference of the protrusion 25 will also be referred to as the "particle diameter". The median particle diameter of the protrusion 25 is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 20 nm or less. The lower limit of the median particle diameter is usually around 2 nm. Here, the particle diameter of the protrusion 25 refers to the deemed diameter calculated by assuming that the outer circumference of the protrusion 25 when viewed from above is a perfect circle, using the area of ​​the portion surrounded by the outer circumference of each protrusion 25 obtained by imaging the antiviral material 10 from above the surface layer 20 and performing image analysis. Specifically, it is calculated as the square root of the value obtained by multiplying the area of ​​the portion surrounded by the outer circumference of the protrusion 25 by 4 and dividing by π.

[0016] The coverage rate of the surface layer 20 on the substrate 30 should be 20% or more. Preferably, the coverage rate of the surface layer 20 on the substrate 30 should be 40% or more, more preferably 50% or more, and even more preferably 70% or more. Here, the coverage rate of the surface layer 20 on the substrate 30 refers to the ratio of the area covered by the protrusions 25 to the surface area of ​​the substrate 30 when the antiviral material 10 is viewed from above from the surface layer 20 side.

[0017] The density of the protrusions 25 that make up the surface layer 20 is 0.0002 pieces / nm 2 That's all. In the following explanation, the density of the protrusions 25 will also be referred to as the "particle density". The particle density of the above-mentioned protrusions 25 is 0.0005 particles / nm 2 Preferably, the density is 0.0010 particles / nm. 2 The above is more preferable. Here, the particle density of the protrusions 25 constituting the surface layer 20 refers to the number of protrusions 25 present per unit area on the substrate 30.

[0018] Furthermore, the thickness of the substrate 30 in the normal direction at the surface layer 20 should be 5 μm or less. Preferably, the thickness of the substrate 30 should be 1 μm or less, more preferably 500 nm or less, and even more preferably 100 nm or less. In the following description, the "thickness in the normal direction" of the substrate 30 at the surface layer 20 refers to the thickness defined to include not only the case where the surface of the substrate 30 is curved, but also the case where the substrate 30 is flat. That is, when the surface of the substrate 30 is curved, it refers to the thickness in the normal direction at the part of the surface of the substrate 30 where the protrusions 25 are formed, and when the substrate 30 is flat, it refers to the thickness in the direction perpendicular to the surface of the substrate 30. By setting the thickness of the surface layer 20 within the above range, it is possible to suppress a decrease in the properties of the antiviral material 10, such as flexibility and light transmittance, and to prevent the surface layer 20 from peeling off from the substrate 30, and to suppress an increase in manufacturing costs. Furthermore, if the effect of increasing the thickness of the surface layer 20 is within an acceptable range, the thickness of the surface layer 20 may exceed 5 μm.

[0019] The material of the base material 30 is not particularly limited, but a polymer material is preferable from the viewpoint of flexibility, processability, and freedom of shape. By directly processing the object to be given antiviral properties and forming the surface layer 20 as an antiviral layer on the surface of the object, the object can be obtained with antiviral activity on its surface. Alternatively, the surface layer 20 may be formed on a sheet-like base material 30, and the resulting sheet-like antiviral material may be placed on the surface of the object to impart antiviral activity to its surface. Alternatively, a fibrous base material may be used as the base material 30. For example, by using a fabric made by thinly processing fibers, such as a woven, knitted, or nonwoven fabric made using fibers, the surface layer 20 can be formed on the surface of the fibers constituting these fibrous base materials to impart antiviral activity. When using a base material 30 composed of polymer fibers, the fiber diameter of the polymer fibers constituting the base material 30 can be 1 μm or less. Even when such fine fibers are used as the base material 30, antiviral activity can be imparted to the surface of the fibrous base material by providing the surface layer 20 having the fine protrusion structure defined in this embodiment.

[0020] By imparting antiviral activity to the surface of the target object as described above, it is possible to suppress contact infections transmitted through viruses that adhere to the surface, for example, by droplets. Furthermore, by using a fibrous material as the base material 30, it becomes possible to rapidly inactivate viruses contained in fluids such as air and water that pass through the fibrous material, and it can be used, for example, as a filter or mask material for gases and solutions.

[0021] B. Method for manufacturing antiviral materials: The method for forming the surface layer 20 on the substrate 30 is not particularly limited, but for example, physical vapor deposition (PVD) can be used. Examples of physical vapor deposition methods include sputtering, pulsed laser deposition (PLD), and vacuum deposition. Alternatively, chemical vapor deposition (CVD) may be used to form the surface layer 20. The method should be appropriately selected considering the shape of the resulting surface layer 20, the constituent materials of the surface layer 20, the material of the substrate 30, and the manufacturing cost.

[0022] Among these methods, sputtering is preferred because it can easily form a desired surface structure. When forming a surface layer 20 on a substrate 30 by sputtering, the desired protruding structure can be formed as the surface structure of the surface layer 20 by appropriately adjusting conditions such as the input power, substrate temperature, atmospheric gas type, atmospheric gas pressure, and target-substrate distance. Generally, the lower the input power to reduce the energy of the sputtered atoms, the higher the atmospheric pressure, the lower the substrate temperature, and the larger the target-substrate distance, the easier it is to form a protruding structure on the surface of the resulting film. Therefore, as conditions for forming the surface layer 20 in this embodiment, it is desirable, for example, that the input power be around 50-200W, the atmospheric pressure be 0.5Pa or higher, and the target-substrate distance be 5cm or higher.

[0023] C. Regarding the precision of the arrangement of the protrusions: The mode in which the antiviral material 10 exhibits antiviral activity is thought to include at least a mode in which the virus is inactivated by "direct contact between the antiviral component and the virus". Therefore, it is thought that the more contact points between the antiviral component and the virus are secured in the surface layer 20, the higher the antiviral activity can be. In the antiviral material 10 of this embodiment, the median diameter of the outer circumference shape of the particulate protrusions 25 when viewed from above (particle diameter), the coverage rate of the surface layer 20 on the substrate 30, and the density of the protrusions 25 constituting the surface layer 20 (particle density) are set within the numerical range described above, and the protrusions 25 are arranged densely in two dimensions without aggregation, thereby increasing the contact between the protrusions 25 and the virus.

[0024] The relationship between the density of the particulate protrusions 25 and antiviral activity will be further explained below using a model. The model described below is for understanding the density of the protrusions 25 in the antiviral material 10 in order to ensure contact between the protrusions 25 and viruses and to exhibit effective antiviral performance. In the model of this embodiment, the collision frequency Fcol, which is the frequency at which the protrusions 25 and viruses come into contact (collide), is used as an indicator of the antiviral effect of the antiviral material 10. The meaning of each symbol used in the model of this embodiment is as follows.

[0025] Rp: Particle diameter of projection 25 Rv: Virus diameter N: Particle spacing coefficient Sp: Particle projection cross-section Sv: Virus projection area Scol: Collision cross section Dp: particle density Fcol: Collision frequency

[0026] Figure 2 is an explanatory diagram showing the relationship between particle density Dp, particle size (particle diameter Rp), and virus size (virus diameter Rv) in the model of this embodiment. The model of this embodiment is a two-dimensional close-packing model, and is a model using a planar regular hexagon, which is a top view of the hexagonal close-packing structure, which is a general three-dimensional structure represented by a regular hexagonal prism. In other words, in this embodiment, the "collision frequency," which is understood as the product of the "collision cross-sectional area" and the "molecular concentration," is adopted in two dimensions as an indicator of the antiviral effect. In Figures 2(A) and 2(B), the protrusions 25 are represented as spheres that are circular in top view and are placed at the vertices of the regular hexagon, and in Figure 2(C), the virus particles are represented as spheres that are circular in top view.

[0027] Here, the size of the virus particles targeted by the antiviral material 10 (virus diameter) is considered to be approximately 20-200 nm. This range of virus diameters overlaps with the desirable range of particle diameter Rp of the protrusions 25 described above. Thus, when the particle diameter Rp and the virus diameter Rv are approximately the same, the influence of the movement of virus particles in the film thickness direction of the surface layer 20 on the frequency of collisions between virus particles and the particle sides (sides of the protrusions 25) is considered to be small. Therefore, in this embodiment, the evaluation was performed while ignoring the movement of virus particles in the film thickness direction of the surface layer 20. Specifically, the protrusions 25 constituting the surface layer 20 were approximated by spheres arranged in two dimensions, and the collision frequency Fcol derived using the two-dimensional model was used as an indicator of the antiviral effect.

[0028] Figure 2(A) shows the state when the particles are packed tightly together, with adjacent protrusions 25 touching each other. Figure 2(B) shows a more sparse arrangement of the protrusions 25 than in Figure 2(A), with adjacent protrusions 25 spaced apart. As shown in Figures 2(A) and (B), the particle spacing coefficient N is a coefficient that determines the interparticle distance, and the distance between adjacent protrusions 25 is expressed as the product of the particle diameter Rp and the particle spacing coefficient N. The value of N is smallest when the particles are packed tightly together as shown in Figure 2(A), and N=1. The particle projection cross section Sp is the area of ​​the circle obtained by orthogonally projecting a sphere with diameter Rp, and is expressed by the following equation (1). The virus projection area Sv is the area of ​​the circle obtained by orthogonally projecting a sphere with diameter Rv, and is expressed by the following equation (2). The collision cross section Scol is expressed by the following equation (3). The particle density Dp corresponds to "the number of protrusions 25 per unit area when the surface layer 20 is viewed from above," and is expressed by equation (4) below. The collision frequency Fcol corresponds to "the number of protrusions 25 present per collision cross-sectional area Scol when the surface layer 20 is viewed from above," and is expressed by equation (5) below. Furthermore, by substituting equations (1) and (2) into equation (3), and substituting equations (3) and (4) obtained by substituting equations (1) and (2) into equation (5), the following equation (6) is derived as an equation representing the collision frequency Fcol, using particle diameter Rp, virus diameter Rv, and particle spacing coefficient N.

[0029]

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[0030] The collision frequency Fcol is given by N as shown in equation (6). -2 It is expressed as the sum of a term proportional to and a term proportional to the square of the value obtained by dividing Rv by the product of Rp and N. Therefore, when the virus diameter Rv is sufficiently large compared to the particle diameter Rp, even if the particle spacing coefficient N is large (even if the particle density Dp is small), it is easier to secure a large value for the latter term in equation (6). As a result, it is understood that a high value for the collision frequency Fcol can be secured.

[0031] Figures 3 and 4 are explanatory diagrams showing the relationship between collision frequency Fcol (antiviral effect), particle spacing coefficient N, and particle diameter Rp. Figure 3 shows the case where the virus diameter Rv is 20 nm, and Figure 4 shows the case where the virus diameter Rv is 100 nm. Specifically, using equation (6) which represents the collision frequency Fcol, the value of collision frequency Fcol was calculated for various values ​​of particle spacing coefficient N for particle diameters Rp of 10 nm, 30 nm, 50 nm, and 1 μm, and the obtained results were plotted by connecting them for each particle diameter Rp. As mentioned above, the size of virus particles (virus diameter) is generally considered to be around 20-200 nm. For example, the virus diameter of relatively small viruses such as bacteriophage Qβ and norovirus is around 20 nm. Also, the virus diameter of coronavirus is around 100 nm. The previously mentioned tendency that a high collision frequency Fcol can be secured even if the particle spacing coefficient N is large (even if the particle density Dp is small) when the virus diameter Rv is sufficiently large compared to the particle diameter Rp can also be seen from Figures 3 and 4.

[0032] Conventional antiviral materials have a relatively large particle spacing coefficient N and a relatively small particle density Dp for the antiviral component. However, even with this configuration, when the size of the particles to be inactivated is relatively large, for example, when the particle diameter Rp is about 1 μm, such as bacteria, it is thought that it was possible to ensure a sufficient collision frequency Fcol and exhibit an inactivating effect. However, when the size of the particles to be inactivated is smaller, for example, when inactivating viruses with a particle diameter Rp of about 20-200 nm, conventional antiviral materials have difficulty fully exhibiting the performance of the antiviral component and obtaining high antiviral activity. In other words, there is a difference in the density of the antiviral component particles required to achieve a high collision frequency Fcol and enhance antiviral activity when the particle diameter Rp is large, such as that of bacteria, and when it is small, such as about 20-200 nm. As can be seen from equation (6), when the diameter Rv of the particles to be inactivated is small, it is considered necessary to reduce the particle diameter Rp of the particles containing the antiviral component, and further reduce the particle spacing coefficient N (increase the particle density Dp).

[0033] Figure 5 is an explanatory diagram showing the relationship between collision frequency Fcol and particle density Dp when the virus diameter Rv is 20 nm. Specifically, using equation (5) which represents the collision frequency Fcol, calculations were performed for each case where the particle diameter Rp is 7 nm, 10 nm, 20 nm, 30 nm, and 50 nm, and the calculation results were plotted with the collision frequency Fcol on the horizontal axis and the particle density Dp on the vertical axis. From Figure 5, it can be understood that when the virus diameter Rv is relatively small, such as 20 nm, the collision frequency Fcol can be increased by increasing the particle density Dp, thereby increasing the antiviral activity.

[0034] In this embodiment, the antiviral material 10 has the median diameter of the outer shape of the protrusions 25 when viewed from above (particle diameter Rp), the density of the protrusions 25 (particle density Dp), and the coverage rate (a value determined by the particle diameter Rp and particle density Dp) within the numerical range described above. By densely arranging the protrusions 25 on the surface layer 20 in this way, even when the virus diameter Rv of the virus particles to be inactivated is relatively small, such as around 20-200 nm, the collision frequency Fcol is increased, thereby enhancing the antiviral activity.

[0035] In the antiviral material 10 of this embodiment, when the virus diameter Rv is set to a relatively small value of 20 nm, the collision frequency Fcol (see equation (5)) obtained by multiplying the measured value of the median diameter of the outer shape of the protrusion 25 when viewed from above (particle diameter Rp), the collision cross-sectional area Scol calculated using equations (1) to (3), and the measured value of the particle density Dp can be 0.5 or more. When the virus diameter Rv is 20 nm, the above collision frequency Fcol is preferably 3.0 or more, more preferably 5.0 or more, and even more preferably 10 or more. By providing the surface layer 20 with densely arranged protrusions 25 that exhibit such a high collision frequency Fcol, the antiviral material 10 can obtain high antiviral activity corresponding to the antiviral component used. In Figures 3 and 4, the line where the collision frequency Fcol is 0.5 is indicated by an arrow.

[0036] Figure 6 is an explanatory diagram showing the results of calculating particle density Dp, coverage of the surface layer 20 on the substrate 30, and collision frequency Fcol, as a typical example, by setting the particle diameter Rp to 7 nm or 30 nm, the virus diameter Rv to 20 nm or 100 nm, and varying the particle spacing coefficient N within a range considered feasible. From Figure 6, when the virus diameter Rv is set to 20 nm, the previously described conditions related to the density of the protrusions 25 on the surface layer 20, namely, the particle diameter Rp being 1 μm or less and the particle density Dp being 0.0002 particles / nm, are met. 2It is understood that by satisfying the above conditions, and the coverage rate of the surface layer 20 on the substrate 30 being 20% ​​or more, it becomes easy to make the collision frequency Fcol 0.5 or more.

[0037] With the antiviral material 10 of this embodiment configured as described above, by densely arranging the protrusions 25 such that the median diameter of the outer shape of the protrusions 25 when viewed from above (particle diameter Rp), the density of the protrusions 25 (particle density Dp), and the coverage rate of the surface layer 20 on the substrate 30 satisfy the aforementioned numerical ranges, it is possible to obtain high antiviral activity by fully exhibiting the performance of the antiviral component while suppressing the amount of antiviral component when targeting viruses with a virus diameter Rv of about 20-200 nm for inactivation.

[0038] In conventionally known antiviral materials, for example, when obtaining an antiviral material (hereinafter also referred to as a "coated film-type antiviral material") by slurrying antiviral component particles and coating them onto the surface of a substrate, the surface area of ​​the antiviral component can be increased by increasing the amount of antiviral component to be coated (the amount of antiviral component particles arranged three-dimensionally), thereby increasing the collision frequency Fcol and enhancing antiviral activity. In this embodiment, by densely arranging the protrusions 25 of the surface layer 20 as described above, the antiviral material 10 can achieve a collision frequency Fcol that is difficult to achieve even with the above-mentioned coated film-type antiviral material, using a smaller amount of antiviral component when the virus diameter Rv of the virus particles to be inactivated is relatively small, such as 20-200 nm. Specifically, for example, when the virus diameter Rv is set to 20 nm, it becomes easy to make the collision frequency Fcol 0.5 or higher.

[0039] Furthermore, according to this embodiment, since high antiviral activity can be obtained while reducing the amount of antiviral components contained in the antiviral material 10 as described above, the impact on the human body and the environment caused by using antiviral components that are metals or metal oxides can be suppressed. In particular, when metallic copper is used as the antiviral component, the antiviral activity is especially high, so the effect of reducing the amount of antiviral component used is enhanced and desirable. Moreover, when metallic copper is used as the antiviral component, the oxidation of metallic copper, which is the antiviral component, can be suppressed by adopting the shape of the surface layer 20 of this embodiment. Therefore, the effect of suppressing the deterioration of the performance of the antiviral material caused by the oxidation of metallic copper, which is the antiviral component, can be obtained. [Examples]

[0040] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the description of these examples.

[0041] <Preparation of each sample> [Sample S1] Sample S1, an antiviral material, was prepared using metallic copper (Cu) as the antiviral component and a 1cm x 1cm, 0.2mm thick polypropylene (PP) sheet as the substrate 30. Specifically, metallic copper was deposited on the polypropylene sheet (hereinafter also referred to as the PP substrate) using the sputtering method to form the surface layer 20. The amount of metallic copper deposited was controlled by a quartz crystal oscillator, and approximately 5 μg was deposited. The thickness of the surface layer 20 was 10 nm. Sample S1 and Samples S2-S4, described later, are the examples of this model. In all of Samples S1-S4, during sputtering, the atmospheric gas pressure was 5 Pa, the substrate temperature was room temperature, the target size was 50 nm in diameter, and the target-substrate distance was 10 cm.

[0042] [Sample S2] The antiviral material for sample S2 was prepared using cuprous oxide (Cu2O) as the antiviral component and a 1cm x 1cm, 0.2mm thick polypropylene (PP) sheet as the substrate 30. Specifically, Cu2O was deposited on the PP substrate using the sputtering method to form the surface layer 20. The amount of Cu2O deposited was controlled by a quartz crystal oscillator, and approximately 5 μg was deposited. The thickness of the surface layer 20 was 20 nm.

[0043] [Sample S3] Sample S3, an antiviral material, was prepared using cupric oxide (CuO) as the antiviral component and a 1cm x 1cm, 0.2mm thick polypropylene (PP) sheet as the substrate 30. Specifically, CuO was deposited on the PP substrate using a sputtering method to form a surface layer 20. The amount of CuO deposited was controlled by a quartz crystal oscillator, and approximately 5 μg was deposited. The thickness of the surface layer 20 was 20 nm.

[0044] [Sample S4] The antiviral material for sample S4 was prepared using silver (Ag) as the antiviral component and a polypropylene (PP) sheet measuring 1 cm x 1 cm with a thickness of 0.2 mm as the substrate 30. Specifically, Ag was deposited on the PP substrate using a sputtering method to form the surface layer 20. The amount of Ag deposited was controlled by a quartz crystal oscillator, and approximately 5 μg was deposited. The thickness of the surface layer 20 was 13 nm.

[0045] Figure 7 is an explanatory diagram showing field emission scanning electron microscope (FE-SEM) observation images of sample S1. Figure 7(A) shows a surface image of the surface of the surface layer 20 observed from the top surface of the antiviral material 10, Figure 7(B) shows a bird's-eye view of the surface layer 20 of the antiviral material 10 viewed from above, and Figure 7(C) shows a cross-sectional image of the cross-section of the antiviral material 10. Figure 8 shows the FE-SEM image of sample S2, Figure 9 shows the FE-SEM image of sample S3, and Figure 10 shows the FE-SEM image of sample S4. Figures 8-10 all show the top view, bird's-eye view, and cross-sectional image in order, similar to Figure 7. In Figures 7-10, the top view in (A) is a 400,000x magnification image. The bird's-eye views in Figures 7(B) and 8(B) are magnified 500,000 times, the bird's-eye view in Figure 9(B) is magnified 300,000 times, and the bird's-eye view in Figure 10(B) is magnified 200,000 times. The cross-sectional view in Figure 7(C) is magnified 1,000,000 times, the cross-sectional views in Figures 8(C) and 10(C) are magnified 600,000 times, and the cross-sectional view in Figure 9(C) is magnified 700,000 times. As shown in Figures 7-10, it was confirmed that samples S1-S4 had a surface layer 20 composed of densely arranged fine protrusions 25 with particle diameters Rp of 2-20 nm. As shown in Figure 10, it was confirmed that it is also possible to form a striped structure in which multiple protrusions 25 are connected.

[0046] Figure 11 is an explanatory diagram showing the X-ray diffraction (XRD) patterns of the surface layer 20 of samples S1-S4. Figure 11(A) shows the results for sample S1, Figure 11(B) shows the results for sample S2, Figure 11(C) shows the results for sample S3, and Figure 11(D) shows the results for sample S4. Figures 11(A), 11(B), 11(C), and 11(D) also show the locations where diffraction lines originating from Cu, Cu2O, CuO, and Ag are generated, respectively. As shown in Figure 11, only diffraction lines originating from Cu, Cu2O, CuO, and Ag were obtained for samples S1, S2, S3, and S4, respectively, confirming that a single-phase surface layer 20 can be formed.

[0047] In samples S1-S4, when forming the surface layer 20 on the PP substrate using the sputtering method, a silicone substrate (hereinafter also referred to as Si substrate) was placed next to the PP to suppress charge-up of the sample and to measure the thickness of the surface layer 20 from a good fracture surface. The antiviral component was similarly deposited on the Si substrate as well. The thickness of the surface layer 20 was measured by fracturing the member made using the Si substrate.

[0048] Figure 12 is an explanatory diagram that shows, as an example, the surface images of the surface layer 20 formed on a PP substrate (Figure 12(A)) and the surface layer 20 formed on a Si substrate (Figure 12(B)) for sample S2 side by side. For samples S1, S3, and S4, it was confirmed that a surface layer 20 with a similar surface structure was formed on both the PP substrate and the Si substrate, similar to sample S2.

[0049] [Sample S5] The PP substrate used as substrate 30 in samples S1-S4 was prepared as sample S5. Sample S5, and samples S6-S10 described later, are comparative examples.

[0050] [Sample S6] Sample S6 is a coating-type antiviral material. A PP substrate measuring 1 cm x 1 cm with a thickness of 0.2 mm was used as the substrate, and Cu nanoparticles (average particle size 25 nm) were used as the antiviral component. The coating amount of Cu nanoparticles per substrate was set to 10 μg. Specifically, in order to adjust the weight of the Cu nanoparticles to be coated, the Cu nanoparticles were weighed and mixed with an ethanol solution at a ratio of 0.5 mg / mL. The solution was then subjected to handshake and ultrasonic dispersion for 10 minutes to uniformly disperse the Cu nanoparticles in the solution. 20 μL of this dispersion was quickly taken using a micropipette and dropped onto the PP substrate, covering the entire surface to achieve the above coating amount.

[0051] [Sample S7] Sample S7 is a coating-type antiviral material. The above-mentioned PP substrate was used as the base material, and Cu nanoparticles (average particle size 25 nm) were used as the antiviral component. The coating amount of Cu nanoparticles per substrate was set to 1000 μg. Specifically, in order to adjust the weight of the Cu nanoparticles to be coated, the Cu nanoparticles were weighed and mixed with ethanol solution at a ratio of 50 mg / mL. The solution was then subjected to handshake and ultrasonic dispersion for 10 minutes to uniformly disperse the Cu nanoparticles in the solution. 20 μL of this dispersion was quickly taken using a micropipette and dropped onto the PP substrate, covering the entire surface to achieve the above coating amount.

[0052] [Sample S8] Sample S8 is a coated antiviral material. The above-mentioned PP substrate was used as the base material, and Cu2O particles (average particle size approximately 1 μm) were used as the antiviral component, with a coating amount of 100 μg of Cu2O particles per substrate. Specifically, 5 mg of Cu2O powder was mixed with 1 mL of ethanol, dispersed by ultrasound, and then the entire surface of the PP substrate was coated with this dispersion so that the coating amount per substrate was 100 μg, thus obtaining Sample S8.

[0053] [Sample S9] Sample S9 is a coated antiviral material. It was prepared in the same manner as Sample S8, except that the above-mentioned PP substrate was used as the base material, Cu2O particles (average particle size approximately 1 μm) were used as the antiviral component, and the amount of Cu2O particles coated per substrate was 1000 μg. [Sample S10] A pure copper plate measuring 1 cm x 1 cm with a thickness of 0.5 mm was prepared as sample S10.

[0054] Figure 13 is an explanatory diagram showing scanning electron microscope (SEM) observation images of samples S6 and S7. Figure 13(A) shows the surface of sample S6, Figure 13(B) shows the surface of sample S7, and Figure 13(C) shows the cross-section of sample S7. For each sample, a 3 nm coating of platinum (Pt) was applied to prevent charge-up before SEM observation. In Figure 13, the white areas are Cu2O particles, and aggregation of Cu2O particles was observed as shown in Figure 13. For samples S6-S9, the particle diameter, number of particles, and coverage rate were determined by image analysis using the observation images obtained as shown in Figure 13, as described later.

[0055] [Preparation of samples using fibrous substrates] Figure 14 shows FE-SEM images of antiviral materials prepared using a nonwoven fabric made of polymer fibers with a fiber diameter of 1 μm or less as the base material 30. Figure 14(A) shows a sample in which Cu2O as an antiviral component was deposited on the base material 30 by sputtering, similar to sample S2. Figure 14(B) shows a sample in which Ag as an antiviral component was deposited on the base material 30 by sputtering, similar to sample S4. Figure 14(C) shows a sample in which zinc (Zn), an antiviral component, was deposited on the base material 30 by sputtering. Figure 14(A) is a 200,000x magnification image, Figure 14(B) is a 100,000x magnification image, and Figure 14(C) is a 300,000x magnification image. As shown in Figure 14, it was confirmed that it is possible to prepare antiviral materials in which the surface of individual fibers constituting a fibrous base material is coated with fine and dense protrusions 25 using various antiviral components such as Cu2O, Ag, and Zn. In the samples shown in Figures 14(A) and 14(B), atomic mapping by energy-dispersive X-ray spectroscopy (EDX) confirmed that the protrusions were composed of Cu and Ag (data not shown). In the samples shown in Figures 14(A) and 14(B), the particle diameter of the protrusions 25 was approximately 10-20 nm, and the film thickness was approximately 10-60 nm. In the sample shown in Figure 14(C), the particle diameter of the protrusions 25 was approximately 20 nm, and the thickness of the surface layer 20, measured from the cross-section of the zinc oxide deposited on a Si substrate placed immediately next to the fibrous substrate during film formation, was approximately 60 nm.

[0056] <Methods for measuring various parameters related to the sample> The particle diameter Rp for each sample was determined by image analysis of SEM images of the surface of the surface layer 20 of each sample. Specifically, the particle diameter Rp was determined as the median diameter of the outer circumference of the protrusion 25 when viewed from above. To suppress the influence of heterogeneity in the dispersion state of the protrusion 25, the evaluation was performed in an area of ​​a square with a side length equal to 10 times the pre-calculated particle diameter or larger. The diameter of the outer circumference of each protrusion 25 was calculated as a deemed diameter, assuming that the outer circumference of the protrusion 25 is a perfect circle, using the area of ​​the region enclosed by the outer circumference of each protrusion 25 obtained by image analysis of the above SEM images.

[0057] The film thickness of the sample having the surface layer 20 was measured using SEM images of the cross-section of the sample in which the antiviral component was deposited on a Si substrate arranged side by side on a PP substrate, as described above.

[0058] Furthermore, the coverage rate of the surface layer 20 on the substrate 30, and the particle density Dp were also determined by image analysis. ImageJ was used as the image analysis software. The Analyze particles command of the above software was used for particle recognition. The Watershed function was used as needed to identify particle boundaries. Whether proper particle recognition was performed was confirmed by comparing it with the SEM image used for analysis. Coverage rate was measured by adjusting the threshold to limit recognition to the particle area, and then measuring the percentage of the area occupied by that region.

[0059] Figure 15 is an explanatory diagram showing the image analysis of sample S1 as an example. Figure 15(A) shows the SEM image of sample S1, Figure 15(B) shows the result of extracting the particle outline by image analysis, Figure 15(C) shows the result of extracting the particle voids for the calculation of coverage by image analysis, and Figure 16(D) shows the particle diameter distribution obtained by image analysis. Particle diameter Rp, coverage, and particle density Dp were measured for other samples using the same process.

[0060] <Method for evaluating antiviral activity> The antiviral activity was evaluated by quantifying changes in the number of infectious viruses using the plaque assay method, with bacteriophage Qβ (hereinafter also referred to as Qβ), a non-enveloped virus, and bacteriophage Φ6 (hereinafter also referred to as Φ6), an enveloped virus. The number of infectious viruses was calculated based on the number of obtained plaques and expressed as Plaque forming units (hereinafter referred to as PFU). For the evaluation of antiviral activity, a virus-containing solution (10 5 -10 6 PFU / specimen) was dropped onto a 10 mm × 10 mm evaluation material (each sample), covered with a stomacher bag cut into 8 mm × 8 mm, and brought into contact with the material for a predetermined period of time. The washing solution that had been in contact with the evaluation material was diluted with peptone-added physiological saline; when Qβ was used, it was brought into contact with the host Escherichia coli for infection, and when Φ6 was used, it was brought into contact with the host Pseudomonas syringae for infection. Thereafter, Qβ was incubated at 37°C for 18 hours and Φ6 was incubated at 25°C for 40 hours, the number of generated plaques was counted, and the number of infectious viruses (N) was calculated. The number of infectious viruses (N0) was determined from the number of plaques appeared in a virus solution not contacted with the evaluation material, and the reduction amount was regarded as antiviral performance. Logarithm of the reduction amount of infectious viruses (Log 10 N-Log 10 N0=Log 10 N / N0) was taken and defined as the "antiviral activity value". For example, an antiviral activity value of -3 means that the number of infectious viruses decreased to 1 / 10 3 , that is, 99.9% of the virus was inactivated.

[0061] <Measurement results relating to the surface layer> Figure 16 is an explanatory diagram summarizing the measured particle diameter Rp, surface layer thickness (film thickness), coverage rate, and particle diameter Rp for each of the samples S1-S4 and S6-S10, as well as the collision frequency Fcol calculated by setting the virus diameter Rv to 20 nm using these measured values, and the observed area when the above measurements were performed. As shown in Figure 16, it was confirmed that samples S1-S4, which are samples having a surface layer 20 with a fine protrusion structure, can be obtained that satisfy the numerical ranges described above for particle diameter Rp, particle density Dp, coverage rate, and film thickness. In comparative example, for sample S6, film thickness and particle density Dp could not be measured due to significant aggregation of Cu nanoparticles. Similarly, for comparative example sample S7, particle density Dp could not be measured due to significant aggregation of Cu nanoparticles. Furthermore, for comparative examples samples S8 and S9, film thickness could not be measured due to aggregation of Cu2O particles.

[0062] In Figure 16, the collision frequency Fcol is shown as "estimated Fcol". This indicates that the value was calculated by setting the virus diameter Rv to 20 nm (estimated) when calculating the collision frequency Fcol using equations (1)-(3) and (5) with the measured particle diameter Rp and particle density Dp. As shown in Figure 16, samples S1-S4, which have a surface layer 20 with fine protrusions, all showed estimated Fcol values ​​significantly exceeding 0.5, confirming that they have a surface structure that can exhibit high contact with viruses.

[0063] <Measurement results of antiviral activity> Figure 17 is an explanatory diagram showing the results of evaluating the antiviral activity of test specimens of sample S1 (Cu), sample S2 (Cu2O), sample S3 (CuO), and sample S5 (control) against bacteriophage Qβ and bacteriophage Φ6. Figure 17(A) shows the results for Qβ, and Figure 17(B) shows the results for Φ6. The horizontal axis shows the contact time between the virus solution and the evaluation material. In the figure, the dashed line indicates the detection limit under the experimental conditions adopted, and the dotted line indicates a line connecting the measurement points as an eye guide. Also, in Figure 17(B), the result for sample S2 with a contact time of 10 minutes is labeled as the lower limit because it was the detection limit under the experimental conditions.

[0064] Figure 18 is an explanatory diagram summarizing the antiviral activity values ​​for samples S1-S5 when the evaluation material was in contact with Qβ and Φ6 for 30 minutes (if the detection limit was reached in a shorter contact time, that fact is noted).

[0065] (Antiviral activity against Qβ) Regarding the antiviral activity against bacteriophage Qβ, as shown in Figure 17(A), comparative example sample S5, composed of a PP substrate, showed an antiviral activity value of less than -1 even after a contact time of 60 minutes, indicating no antiviral activity against Qβ. In contrast, among samples S1-S4, which have a surface layer 20 with fine protrusions, sample S1, which contains metallic copper as an antiviral component, showed the highest antiviral effect, with the amount of infectious virus falling below the detection limit (antiviral activity value of -4 or higher) after a contact time of only 10 minutes. Next, sample S2, which contains Cu2O as an antiviral component, showed the amount of infectious virus falling below the detection limit (antiviral activity value of -4 or higher) after a contact time of 30 minutes. Thus, when using metallic copper or Cu2O as an antiviral component, it was possible to inactivate approximately 99.99% of Qβ in a short time of less than 30 minutes of contact. Sample S3, which contains CuO as an antiviral component, showed an antiviral activity value of -2.3 after a 30-minute contact time, which is significantly higher than the previously reported antiviral activity value of -0.01 against Qβ after a 30-minute contact time (Journal of Hazardous Materials 235-236 (2012) 265). While it was previously known that antiviral activity is highest for Cu2O and then CuO, it was confirmed that high viral activity can be achieved even when using CuO as an antiviral component by forming a surface layer 20 with a fine protrusion structure. Therefore, for example, when using metallic copper as an antiviral component, even if the oxidation of Cu progresses to Cu2O or CuO, it is thought that the decrease in antiviral performance against Qβ, etc., due to oxidation can be suppressed. Furthermore, as shown in Figure 18, sample S4, which contains Ag as an antiviral component, also showed high antiviral activity of -0.9 after a 30-minute contact time, compared to comparative examples and conventional knowledge.

[0066] (Antiviral activity against Φ6) Regarding the antiviral activity against bacteriophage Φ6, as shown in Figure 17(B), comparative example sample S5, composed of a PP substrate, showed an antiviral activity value of less than -1 even after a contact time of 60 minutes, indicating no antiviral activity against Φ6. In contrast, among samples S1-S4, which have a surface layer 20 with fine protrusions, sample S1, which contains metallic copper as an antiviral component, showed the highest antiviral effect, with the amount of infectious virus falling below the detection limit (antiviral activity value of -4.3 or higher) after a contact time of only 10 minutes. Next, sample S2, which contains Cu2O as an antiviral component, also showed an amount of infectious virus falling below the detection limit (antiviral activity value of -4.3 or higher) after a contact time of 30 minutes. Thus, when using metallic copper or Cu2O as an antiviral component, it was possible to inactivate approximately 99.99% of Φ6 in a short time of less than 30 minutes of contact. Compared to the previously reported result (Journal of Hazardous Materials 312 (2016) 1.) of an antiviral activity value of -3.7 after 30 minutes of contact with the influenza A virus, which is the same enveloped virus as Φ6, a higher effect was observed. Sample S3, which contains CuO as an antiviral component, had an antiviral activity value of -1.6 after 30 minutes of contact. This result shows a much higher effect compared to the previously reported result (Journal of Hazardous Materials 312 (2016) 1.) of an antiviral activity value of -0.01 after 30 minutes of contact with the influenza A virus, which is the same enveloped virus as Φ6. It was previously known that the antiviral activity is higher for Cu2O followed by CuO, but it was confirmed that by forming a surface layer 20 with a fine protrusion structure, high viral activity can be achieved even when using CuO as an antiviral component, as described above. Therefore, for example, when metallic copper is used as an antiviral component, even if the oxidation of Cu progresses to Cu2O or CuO, it is thought that the decrease in antiviral performance against Φ6, etc., due to oxidation can be suppressed.Furthermore, as shown in Figure 18, sample S4, which contains Ag as an antiviral component, also showed high antiviral activity against Φ6, with an antiviral activity value of -4.3 or higher after a contact time of 10 minutes.

[0067] (Comparison of protruding structure and coated film type) Figure 19 is an explanatory diagram showing the results of investigating the antiviral activity values ​​against bacteriophage Qβ for samples S1, S6, S7, and S10. As previously described, sample S1 is an antiviral material made using 5 μg of metallic copper as an antiviral component, with a surface layer 20 having a fine protrusion structure; sample S6 is a coated film type antiviral material with a coating amount of Cu nanoparticles of 10 μg per substrate; sample S7 is a coated film type antiviral material with a coating amount of Cu nanoparticles of 1000 μg per substrate; and sample S10 is a pure copper plate. Figure 19 shows the antiviral activity values ​​when the contact time between each sample and Qβ was 30 minutes. In Figure 19, the error bars indicate the standard deviation when three measurements were taken.

[0068] As shown in Figure 19, sample S1 showed a very high antiviral activity value of -4 when in contact with Qβ for 20 minutes. In contrast, sample S7, a coated film type using 1000 μg of Cu nanoparticles, showed a high antiviral activity value of -3, but its effect was an order of magnitude lower despite having 200 times the weight of copper compared to sample S1. The antiviral activity value of sample S6, a coated film type using 10 μg of Cu nanoparticles, was -1.8, which was more than two orders of magnitude lower than sample 1. The antiviral activity value of sample S10, which is made of a copper plate, was -2.8, and its antiviral performance was inferior to sample S1, even though the entire surface of the sample was coated with copper. Thus, by comparing cases where the same metallic copper is used as the antiviral component, it was confirmed that antiviral materials with a surface layer 20 having a fine protrusion structure exhibit higher antiviral performance than coated film type antiviral materials with a much larger copper weight, or copper plates with the entire surface coated with copper. This is thought to be because the antiviral material, which has a surface layer 20 with a fine protrusion structure, exhibits a high collision frequency Fcol, indicating that it has a surface structure that can exhibit high contact with viruses.

[0069] As shown in Figure 16, Sample 1 had a particle diameter Rp of 7 nm and a coverage of 84%, and the estimated Fcol calculated using these values ​​for a virus diameter Rv of 20 nm was 7.68. Sample S6, which contained 10 μg of Cu nanoparticles, had a particle diameter Rp of 30 nm and a coverage of 3%, and the estimated Fcol calculated from these values ​​was a small 0.04. Sample S7, which contained 1000 μg of Cu nanoparticles, had a particle diameter Rp of 30 nm and a coverage of 98%, and the estimated Fcol calculated from these values ​​was 1.3. The high coverage of 98% in Sample S7 suggests that the Cu nanoparticles are aggregated in three dimensions. In the two-dimensional close-packing model explained using Figure 2, the coverage in close-packing (the state in Figure 2(A), N=1) is calculated to be 90.7%, and Sample S7 exceeds this value. Furthermore, the cross-sectional SEM image of sample S7 (Figure 13(C)), taken to measure the thickness of sample S7, also confirmed the three-dimensional aggregation of Cu nanoparticles. Thus, in the coated film type antiviral material, an extremely large amount of antiviral component, approximately 1000 μg, was required to create a surface structure that exhibits high contactability with viruses, such as a collision frequency Fcol of 0.5 or higher. Similarly, as can be seen from samples S8 and S9 in Figure 16, when Cu2O particles were used as the antiviral component, an extremely large amount of antiviral component, approximately 1000 μg, was required to create a surface structure that exhibits high contactability with viruses, such as a collision frequency Fcol of 0.5 or higher. In contrast, samples S1-S4, which have a surface layer 20 with a fine protrusion structure, all show estimated Fcol values ​​significantly exceeding 0.5, even with an extremely small amount of antiviral component of 5 μg per sample, as shown in Figure 16. Thus, it was confirmed that the presence of a fine protrusion structure allows for high contact with viruses despite a low amount of antiviral components.

[0070] <Evaluation of the oxidation rate of metallic copper> To evaluate the resistance of metallic copper, an antiviral component that forms a fine protrusion structure, to oxidation was compared between Sample 1, which used metallic copper as an antiviral component, and commercially available copper powder (particle size approximately 1 μm). For Sample 1, XRD patterns were obtained for Sample 1 immediately after preparation and for Sample 1 after exposure to air for 3 days. For the commercially available copper powder, XRD patterns were obtained for copper powder immediately after opening and for copper powder after exposure to air for 3 days.

[0071] Figure 20 is an explanatory diagram showing the XRD pattern for evaluating the resistance to oxidation. Figure 20(A) shows the results for Sample 1, and Figure 20(B) shows the results for commercially available copper powder. Figures 20(A) and 20(B) also show the locations where diffraction lines originating from Cu and Cu2O occur, respectively. After subtracting the background of the obtained pattern, the intensity ratio I of the intensity of the strongest Cu line (2Θ=42.6°) to the intensity of the strongest copper(I) oxide line (2Θ=36.4°) is calculated. Cu2O / Cu The percentage increase I from the above 3-day processing 3days Cu2O / Cu / I 0 Cu2O / Cu In Sample 1, the amount increased by 15%, while in the commercially available copper powder, it increased 4.4 times. This suggests that the formation of a fine protrusion structure slows down the oxidation rate of metallic copper, thus stabilizing it. Furthermore, considering that the commercially available copper powder has a particle size of approximately 1 μm, and the particle diameter Rp of Sample 1 is approximately 10 nm, Sample 1 is considered stable against oxidation despite having a large specific surface area due to the formation of a fine protrusion structure.

[0072] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-mentioned problems, or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]

[0073] 20… Surface layer 25…protrusion 30…substrate

Claims

1. An antiviral material used to exert antiviral activity, Substrate and A surface layer covering at least a portion of the surface of the substrate, comprising a surface layer containing, as a main component, one or more of the following as an antiviral component which is a metal or metal oxide: copper, silver, zinc, iron, and their oxides, and having a plurality of particulate protrusions arranged two-dimensionally along the surface of the substrate and exposed on the surface of the antiviral material, Equipped with, In the surface portion, the median diameter of the outer circumference shape of each of the protrusions when viewed from above is 1 μm or less. The density of the protrusions constituting the surface layer is 0.0002 particles / nm ２ That's all. The coverage rate of the surface layer on the substrate is 20% or more. Antiviral agent.

2. The antiviral material according to claim 1, The aforementioned antiviral component is metallic copper. Antiviral agent.

3. An antiviral material according to claim 1 or 2, The substrate is a polymer fiber. Antiviral agent.

4. The antiviral material according to claim 3, The polymer fiber has a fiber diameter of 1 μm or less. Antiviral agent.

5. An antiviral material according to any one of claims 1 to 4, The plurality of protrusions constituting the surface layer have a median diameter of 100 nm or less when viewed from above. Antiviral agent.

6. An antiviral material according to any one of claims 1 to 5, The density of the protrusions constituting the surface layer is 0.0005 particles / nm ２ That's all. Antiviral agent.

7. An antiviral material according to any one of claims 1 to 6, The coverage rate of the surface layer on the substrate is 40% or more. Antiviral agent.

8. An antiviral material according to any one of claims 1 to 7, The thickness of the substrate in the normal direction in the surface layer is 5 μm or less. Antiviral agent.

9. An antiviral material according to any one of claims 1 to 8, The particle diameter Rp is defined as the median of the outer diameter of the protrusion when viewed from above, and the virus diameter Rv is set to 20 nm. The collision frequency Fcol obtained by multiplying the collision cross-sectional area Scol, calculated using the following equations (1)-(3), by the particle density Dp, which is the density of the protrusion, is 0.5 or greater. Antiviral agent. [Math 1] [Math 2] [Math 3]

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