JP2019156799A - Antibacterial member - Google Patents

Abstract

To provide an antibacterial member that achieves high antibacterial properties without providing an antibacterial coat.SOLUTION: An antibacterial member (10) has a base material (11), and a plurality of projections (12) provided on the surface of the base material (11), each projection (12) having a diameter of 0.5 μm or more and 20 μm or less, and each projection (12) having a Young's modulus of more than 0.004 GPa and 5 GPa or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antibacterial member.

  In recent years, nosocomial infections in the medical field and infectious disease epidemics in the city have become problems. In addition, as the quality of life improves, people's awareness of hygiene has increased, and antibacterial needs for food and home appliances have increased.

Antibacterial members that have been proposed so far have components (antibacterial active ingredients) such as antibacterial metal elements (such as copper (Cu) and silver (Ag)) and ceramics (TiO ₂ ) on the surface of the substrate. Antibacterial properties are imparted by forming a coating film. For example, in Patent Document 1, stainless steel is used as a base, a Zn plating layer or a Zn alloy plating layer is formed thereon, and a thermosetting coating containing an antibacterial / antifungal agent is applied to provide excellent durability. An antibacterial / antifungal coated steel sheet is disclosed (Claim 1). Antibacterial / antifungal agents are inorganic chemicals such as Ag, Cu and Zn, compound chemicals such as zinc phosphate and zinc oxide, thiazole, It is disclosed that it is one or more selected from organic drugs such as imidazole (Claim 3).

JP-A-8-156175

  In the above-described method for providing an antibacterial film, the antibacterial active ingredient is only exposed to several percent at most on the surface of the base material, and the antibacterial performance may not be sufficient. In order to ensure sufficient performance, the amount of the antibacterial active ingredient dispersed on the surface of the member can be increased, but the amount of dispersion is limited due to the stability and strength of the antibacterial film. In the case of Ag, there is also a problem that the price is high, and if the amount of dispersion is excessively increased, the cost is increased. In addition, when there is one kind of antibacterial active ingredient, there is a high possibility that resistant bacteria will be produced, and there is a possibility that new bacteria will be produced.

  In view of the above circumstances, an object of the present invention is to provide an antibacterial member that realizes high antibacterial properties without providing an antibacterial film.

  In order to solve the above problems, the antibacterial member of the present invention has a base material and a plurality of protrusions provided on the surface of the base material, the diameter of the protrusion is 0.5 μm or more and 20 μm or less, and the Young's modulus of the protrusion Is greater than 0.004 GPa and 5 GPa or less.

  More specific configurations of the present invention are described in the claims.

  ADVANTAGE OF THE INVENTION According to this invention, the antibacterial member which implement | achieves high antibacterial property can be provided, without providing an antibacterial film.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

The perspective view which shows the antibacterial member of this invention typically Flow diagram explaining the mechanism of biofilm formation on the surface of the substrate The top view which shows the 1st example of arrangement | sequence of the processus | protrusion of the antibacterial member of this invention The top view which shows the 2nd example of arrangement | sequence of the processus | protrusion of the antibacterial member of this invention Sectional drawing which shows the 1st example of the shape of the base material of the antibacterial member of this invention The perspective view which shows the 2nd example of the shape of the base material of the antibacterial member of this invention SEM observation photograph of the surface of the antibacterial member of Example 1 SEM observation photograph of the surface of the antibacterial member of Comparative Example 1 SEM observation photograph of surface after water resistance evaluation of antibacterial member of Comparative Example 2

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In addition, in each figure, about the same component or the same component, the same code | symbol is attached | subjected and those overlapping description is abbreviate | omitted suitably.

  FIG. 1 is a perspective view schematically showing an antibacterial member of the present invention. As shown in FIG. 1, the antibacterial member 10 includes a base material 11 and a plurality of protrusions 12 provided on the surface of the base material 11. Such an assembly of protrusions 12 is also referred to as a “pillar structure”. The projections 12 form a fine concavo-convex structure on the surface of the substrate 11. In the present invention, “fungus” is a general term for all kinds of microorganisms such as bacteria, yeast, and mold.

  As described above, conventionally, an antibacterial film is provided on the surface of a member to kill bacteria, but the present invention is composed of a biofilm (extracellular polysaccharide secreted by bacteria and fungi) with the surface structure of the substrate. It is an epoch-making thing that suppresses the growth of a three-dimensional structure. Since the fungus itself has little adverse effect on the human body and the biofilm often has an adverse effect on the human body, if the growth of the biofilm can be suppressed, it is very useful as an antibacterial member.

  Hereinafter, the mechanism by which the biofilm is formed on the substrate and the mechanism by which the antibacterial member of the present invention suppresses the growth of the biofilm will be described. FIG. 2 is a flow diagram illustrating the mechanism by which a biofilm is formed on the surface of a substrate. As shown in FIG. 2, the biofilm occurs in the following order:

S1: When a clean substrate comes into contact with water, bacteria (pioneer bacteria) adhere to the interface between the water and the substrate. S2: Extrapolysaccharide (EPS) secreted on the surface of the bacteria S3: Pioneer bacteria start to grow and primary colonies covered with polysaccharides (glycocalyx) are formed. S4: Glycocalix takes up other types of fungal cells and becomes primary. Secondary colonies that metabolize the excrement of colonies (pioneer colonies) are formed in the upper layer of the primary colonies. As shown in FIG. 1, the antibacterial member 10 of the present invention is provided with a protrusion 12 on the surface of a base material 11 and an uneven structure. There By being formed, bacteria scaffold become structurally unstable in the process of forming the primary colonies considered to be effective to break the internal stresses of the primary colony itself. Therefore, it is considered that the process after S3 does not occur and the growth of the biofilm is suppressed.

  The diameter of the protrusion 12 is 0.5 μm or more and 20 μm or less. Within this range, it is preferable that the diameter of the protrusion 12 has a diameter comparable to that of a target bacterium (hereinafter referred to as “target bacterium”) whose growth is to be suppressed. Even when the diameter of the protrusion 12 is too larger than that of the target bacterium, or when the diameter of the protrusion 12 is too smaller than that of the target bacterium, the primary colony cannot be effectively broken. In addition, about the diameter of the processus | protrusion 12 being "the same level" with the magnitude | size of object microbe, both do not necessarily need to be the same. The diameter of the protrusion 12 should just be in the range of the value which can acquire the effect of a primary colony fracture | rupture. The diameter of the protrusion 12 can be determined by performing an experiment to verify the breaking effect for each target bacterium. The diameters of the target bacteria are, for example, bacteria: about 0.5 μm, yeast: about 5 μm, and mold: about 20 μm.

  The shape of the protrusion 12 is a cylindrical shape in FIG. 1, but is not limited thereto. For example, it may be a polygonal prism such as a triangular prism or a quadrangular prism. In this case, the “diameter of the protrusion 12” means the diameter of the circumscribed circle.

  The Young's modulus of the protrusion 12 is preferably greater than 0.004 GPa and not greater than 5 GPa. When the Young's modulus of the protrusion 12 is less than 0.004 GPa, the structural stability (water resistance) of the protrusion 12 in water becomes insufficient. If the Young's modulus of the protrusion 12 is greater than 5 GPa, the primary colony breaking effect is not sufficient.

  FIG. 3A is a top view showing a first example of the array of protrusions of the antibacterial member of the present invention, and FIG. 3B is a top view showing a second example of the array of protrusions of the antibacterial member of the present invention. The arrangement of the protrusions 12 on the base material 11 of the antibacterial member 10 of the present invention is not particularly limited, but for example, as shown in FIG. Moreover, as shown to FIG. 3B, a three-way lattice shape may be sufficient.

  The distance L (pitch interval) between the centers of adjacent protrusions 12 is preferably 1.5 times or more and less than 3 times the diameter of the protrusions 12. When the distance L is less than 1.5 times the diameter of the protrusion 12, a sufficient amount of the uneven structure cannot be secured, and the effect of the uneven structure (the effect of suppressing the biofilm by breaking the primary colony) is sufficiently obtained. I can't. On the other hand, if the distance L is 3 times or more the diameter of the protrusion 12, the ratio of the recesses becomes too large, and bacteria enter the recesses, so that the effect of suppressing biofilm growth cannot be obtained sufficiently.

  The aspect ratio (height / diameter) of the protrusion 12 is preferably 1 or more. If the aspect ratio is less than 1, the effect of the concavo-convex structure cannot be sufficiently obtained.

  The material of the base material 11 is not particularly limited as long as the protrusion 12 can be formed, and can be selected according to a member to be given antibacterial properties. For example, resins such as epoxy resins, acrylic resins, PDMS (polydimethylsiloxane), and COP (cycloolefin polymer) can be used. Moreover, metals, such as stainless steel, may be sufficient.

  4A is a side view showing a first example of the shape of the substrate of the antibacterial member of the present invention, and FIG. 4B is a perspective view showing a second example of the shape of the substrate of the antibacterial member of the present invention. The shape of the substrate 11 is not particularly limited as long as the protrusion 12 can be formed, and can be selected according to a member to be given antibacterial properties. For example, as shown in FIGS. 1 and 4A, it may be a film. When the substrate 11 is in the form of a film, advantages such as improved portability and ease of construction at the site where the antibacterial member is used can be obtained. If the adhesive 13 is provided on the surface opposite to the surface on which the protrusions 12 are provided, the adhesive 13 can be easily attached to a member to be given antibacterial properties.

  Moreover, as shown to FIG. 4B, base material 11 'may be tubular. In this case, the protrusion 12 may be provided on the inner surface of the tubular base material 11 ′. The antibacterial member 10 ′ having such a shape can be applied to a washing tub of a drum type washing machine.

  Next, the manufacturing method of the antimicrobial member mentioned above is demonstrated. As shown to FIG. 4A, when the base material 11 is film-form resin, the processus | protrusion 12 can be produced by nanoimprint process, for example. Specifically, the protrusion 12 can be formed on the surface of the resin film substrate by pressing a metal mold having an uneven structure against the resin film and applying heat.

  Moreover, when the base material 11 is a metal, the processus | protrusion 12 can be formed in the surface of a metal base material, for example by metal printing process. Specifically, the protrusion 12 can be formed on the surface of the metal substrate by pressing a metal mold having an uneven structure against the metal substrate and applying heat and pressure.

  As shown in FIG. 4B, when the base material 11 is a metal tubular member and the protrusion 12 is provided inside the tubular member, the antibacterial member 10 'can be produced using, for example, a roll technique. Specifically, by rotating the base material 11 ′ while pressing the base material 11 ′ against a cylindrical original plate having a concavo-convex structure on the outer surface, the base material is formed into a tubular shape while forming protrusions 12 on the surface of the base material 11 ′. Can be molded.

  Since the nanoimprint process, the metal print process, and the roll technology described above have part of the surface of the base material 11, 11 ′ as the protrusion 12, the antibacterial member 10, 10 ′ has the base material 11, 11 ′ and the protrusion 12. It becomes a molded object. Of course, as long as sufficient adhesion between the base materials 11 and 11 ′ and the protrusions 12 is obtained, the base materials 11 and 11 ′ and the protrusions 12 may be separately prepared and bonded.

  Hereinafter, the present invention will be described in more detail based on examples.

(1) Confirmation of biofilm suppression effect Two antibacterial members (Example 1 and Comparative Example 1) in which the diameter of the protrusion 12 was changed using a resin film as the substrate 11 were produced. The resin film was made of COP (Young's modulus: 0.22 GPa). The size of the protrusion 12 of the antibacterial member of Example 1 was 1 μm, and the size of the protrusion 12 of Comparative Example 1 was 5 μm. The pitch interval L was 1.75 times the diameter of the protrusion 12 and the aspect ratio of the protrusion 12 was 1. The protrusions 12 were formed on the resin film by nanoimprinting a nickel mold.

Bacteria were cultured on the antibacterial member 10 described above by the following procedure. As a test bacterium, Staphylococcus aureus (diameter: about 1 μm) was used. Test bacteria count was obtained ¹⁰ 7 ^~10 8 / mL in until triple Case Soy (SCD) broth (Trypcase Soy Broth) test bacteria liquid was cultured in suspension medium. The glass petri dish and antibacterial member 10 were sterilized by high-pressure steam (121 ° C., 15 minutes), and the antibacterial member 10 of Example 1 and Comparative Example 1 was placed in the glass petri dish, and then the test bacterial solution was added. The SCD broth medium was changed once a day and cultured for 21 days.

  FIG. 5 is a SEM observation photograph of the surface of the antibacterial member of Example 1, and FIG. 6 is a SEM observation photograph of the surface of the antibacterial member of Comparative Example 1. In both the antibacterial members of Example 1 and Comparative Example 1, a region where the protrusions 12 are provided (region surrounded by a dotted line in FIGS. 5 and 6) and a region where the protrusions 12 are not provided (in FIGS. 5 and 6) Area other than the area surrounded by the dotted line). As shown in FIGS. 5 and 6, in both the antibacterial members of Example 1 and Comparative Example 1, the bacteria 20 are proliferating in the region where the protrusions 12 are not provided.

  On the other hand, when looking at the area where the protrusions 12 are provided, the antimicrobial member of Example 1 has almost no bacteria growing, whereas in the antimicrobial member of Comparative Example 1, the area where the bacteria 20 are provided with the protrusions 12. It has also proliferated. From this, it was found that the antibacterial member provided with the protrusions 12 having the same diameter as that of Staphylococcus aureus can suppress the growth of the bacteria.

(2) Water resistance evaluation of antibacterial member Next, the resin material of the base material was changed, and antibacterial members (Examples 2 to 4 and Comparative Example 2) having protrusions 12 having a diameter of 1 μm and a height of 5 μm were prepared by nanoimprinting. The pitch interval L was 1.75 times the diameter of the protrusion 12 and the aspect ratio of the protrusion 12 was 1. The materials of the antibacterial members of Examples 1 to 3 and Comparative Example 2 and their Young's moduli are shown in Table 1 described later. Young's modulus was measured using the nanoindentation method.

  After the produced antibacterial member was immersed in water, the surface structure was observed by SEM (Scanning Electron Microscope), and water resistance (structural stability in water) was evaluated. As a result of the observation, the projections 12 are not bonded to each other and the concavo-convex structure on the base material surface is not collapsed. ". The results of water resistance evaluation are also shown in Table 1 described later.

  As shown in Table 1, in Examples 1 to 3 where the Young's modulus of the material of the antibacterial member satisfies the provisions of the present invention, as a result of SEM observation, the protrusions 12 are not bonded to each other, and the results of the water resistance evaluation are all “Pass”. On the other hand, in Comparative Example 2 in which the Young's modulus of the material of the antibacterial member does not satisfy the definition of the present invention, the result of the water resistance evaluation was “failed”.

  FIG. 7 is a SEM observation photograph of the surface of the antibacterial member of Comparative Example 2 after the water resistance test. As shown in FIG. 7, a phenomenon was observed in which the protrusions 12 were bonded to each other and the uneven structure was broken. This is considered that the strength of the material of the antibacterial member of Comparative Example 2 is weak (Young's modulus: 0.002 to 0.004 GPa), and the protrusions 12 are bonded to each other by a force such as surface tension or static electricity.

From this, it was proved that the protrusion 12 Young's modulus is preferably 0.005 GPa or more and 5 GPa or less in order to keep the uneven structure on the surface of the substrate 11 stable.

  As described above, according to the present invention, it was shown that an antibacterial member capable of suppressing biofilm growth on the surface of a member to be antibacterial can be provided without providing an antibacterial film. Moreover, even when it contacted with water, the uneven structure provided in the surface of the base material 11 can be maintained stably, and it was shown that an antimicrobial effect can be maintained. The antibacterial member of the present invention can be used in various fields such as medical care, food, and electrical appliances.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  10, 10 '... antibacterial member, 11, 11' ... substrate, 12 ... projection, 13 ... adhesive, 20 ... fungus, L ... pitch interval.

Claims (7)

A substrate and a plurality of protrusions provided on the surface of the substrate;
The diameter of the protrusion is 0.5 μm or more and 20 μm or less,
The antibacterial member, wherein the Young's modulus of the protrusion is greater than 0.004 GPa and 5 GPa or less.   The antibacterial member according to claim 1, wherein the distance between the centers of the adjacent protrusions is 1.5 times or more and less than 3 times the diameter of the protrusions.   The antibacterial member according to claim 1, wherein a ratio of a height and a diameter of the protrusion is 1 or more.   The said base material consists of a film-like member, The said protrusion is provided in one surface of the said film-like member, The adhesive agent is provided in the other surface of the said member. 4. The antibacterial member according to any one of 3 above.   The antibacterial member according to any one of claims 1 to 3, wherein the base material is a metal.   The antibacterial member according to any one of claims 1 to 3, wherein the base member is formed of a tubular member, and the protrusion is provided inside the tubular member.   The antibacterial member according to any one of claims 1 to 3, wherein the base material and the protrusion are integrally formed.

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