Antibacterial material

Abstract

Provided is an antibacterial material that comprises a material comprising a nanofiber and / or a two-dimensional substance each represented by the formula: MQaOb (wherein M represents at least one element selected from the group consisting of elements in groups 3, 4, 5, 6, and 7, Q represents at least one element selected from the group consisting of elements in groups 12, 13, 14, 15, and 16 (excluding O), a represents a number of 0 to 2 inclusive, and b represents a number of more than 0 but not more than 2).

Description

antibacterial material

[0001] The present disclosure relates to antimicrobial materials.

[0002] Conventionally, as an oxide containing a metal, for example, TiO ２ For example, AEROXIDE (registered trademark) TiO ２ P-25 is a hydrophilic titanium dioxide with a particle size of 20 to 30 nm and a very high specific surface area. As shown in Non-Patent Document 1, titanium dioxide is suitable for many catalytic applications, particularly photocatalytic applications, due to the ratio of its anatase and rutile crystal structures, and the photocatalytic effect is known to provide, for example, self-cleaning properties in inorganic compositions.

[0003] Teruhisa Ohno, Koji Sarukawa, Kojiro Tokieda, Michio Matsumura, Morphology of a TiO2 Photocatalyst (Degussa, P-25) Consisting of Anatase and Rutile Crystalline Phases, Journal of Catalysis, Volume 203, Issue 1, 2001, Pages 82-86

[0004] Known TiO ２ However, TiO is difficult to disperse in water and aqueous polymer solutions and tends to aggregate. ２ Even if a coating film or the like is formed using an aqueous solution containing TiO ２ However, even when the coating film is used as an antibacterial sheet, TiO ２ The antibacterial properties of TiO in aqueous solution or polymer aqueous solution were not fully exhibited. ２ It is conceivable to add a dispersant to improve the dispersibility of the antibacterial agent. However, the presence of the dispersant may reduce the antibacterial activity. Furthermore, there is also the problem that the dispersant may bleed out.

[0005] The present disclosure has been made in view of the above circumstances, and its object is to provide a novel antibacterial material with high antibacterial properties.

[0006] According to one aspect of the present disclosure, a compound of the formula: ａ O ｂ (wherein M is at least one element selected from the group consisting of Groups 3, 4, 5, 6, and 7; Q is at least one element selected from the group consisting of Groups 12, 13, 14, 15, and 16 (excluding O); a is 0 or more and 2 or less; and b is 0 or more and 2 or less.)

[0007] In accordance with the present disclosure, novel antimicrobial materials are provided.

[0008] Conventional TiO as a filler ２ FIG. 1 is an explanatory diagram of the fracture of a polymer composite containing particles of MQO of the present embodiment as a filler; FIG. 2 is a diagram showing the results of Raman spectroscopic analysis of a material (TiCO) produced in an example; FIG. 3 is an XRD pattern of a material (TiCO) produced in an example; FIG. 4 is a graph showing the results of an antibacterial evaluation test (test bacteria is Escherichia coli) in an example; FIG. 5 is a graph showing the results of an antibacterial evaluation test (test bacteria is Staphylococcus aureus) in an example; FIG. 6 is a graph showing the results of an antibacterial evaluation test (test bacteria is Staphylococcus aureus) in an example; ２ 1 shows the results of evaluating the dispersibility of the aqueous dispersion of titanium dioxide (TiO ２ 10 is a graph showing the results of evaluating the dispersibility of an aqueous polyurethane dispersion of a material (TiCO) produced in an example. FIG. 11 is a graph showing the results of evaluating the dispersibility of an aqueous polyurethane dispersion of a material (TiCO) produced in an example. FIG. 12 is an XRD pattern of a material (TiCO / polyurethane composite material) produced in an example. FIG. 13 is a graph showing the XRD patterns of FIG. 4 and FIG. 10 superimposed on each other.

[0009] [Antibacterial Material] This embodiment relates to an antibacterial material including a material containing specific nanofibers and / or two-dimensional materials. In this disclosure, the simple term "material" refers to a "material containing nanofibers and / or two-dimensional materials" (in other words, a material containing at least one of nanofibers and two-dimensional materials). In this embodiment, a material containing nanofibers and / or two-dimensional materials typically refers to a material that is solid and does not contain a binder or the like (e.g., a polymer). In a narrower sense, a material containing nanofibers and / or two-dimensional materials can refer to a material that is substantially composed of at least one of nanofibers and two-dimensional materials (which may include other objects, impurities, etc. that may inevitably be mixed in). However, materials containing nanofibers and / or two-dimensional materials are not limited to these.

[0010] The antibacterial material of this embodiment includes nanofibers and / or two-dimensional materials of a predetermined material (substance). The predetermined material that can be used in this embodiment is represented by the following formula (1): MQ ａ O ｂ ... (1) (In the formula, M is at least one element selected from the group consisting of Groups 3, 4, 5, 6 and 7, and may include at least one element selected from the group consisting of so-called early transition metals, for example, Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn, and preferably at least one element selected from the group consisting of Ti, V, Cr, Mo and Mn; Q is at least one element selected from the group consisting of Groups 12, 13, 14, 15 and 16 (excluding O), and may include at least one element selected from the group consisting of B, C, N, Si, P and S; a is 0 or more and 2 or less; and b is 0 or more and 2 or less.)

[0011] The above-mentioned predetermined material will be hereinafter also referred to simply as "MQO." Examples of MQO include TiO ２ , TiCO, TiCON, VO ２ , VCO, VCON, CrO ２ , CrCO, CrCON, MoO ２, MoCO, MoCON, MnO ２ , MnCO, MnCON, and the like. For example, in formula (1), M may be Ti and Q may be C. Also, for example, in formula (1), a may not be 0. That is, a may be greater than 0, for example, 1 or greater.

[0012] MQO has a crystal structure different from the hexagonal system. Although the present embodiment is not bound by any theory, the crystal structure of MQO is currently considered to be anatase type, lepidocrocite type, or a mixture of these. For example, the crystal structure of MQO may be lepidocrocite type.

[0013] MQO can be produced, for example, using a first raw material and a second raw material as follows: The first raw material contains at least M, and the second raw material contains at least Q, and the first raw material and the second raw material are capable of reacting in a protic solvent to produce MQO.

[0014] As the first raw material, a material represented by the following formula (2) can be used: M ｃ A １ ｄ ... (2) (wherein M is as defined above, A １ is at least one element selected from the group consisting of Groups 12, 13, 14, 15, and 16, and may include, for example, at least one element selected from the group consisting of B, C, N, O, Si, P, and S; and c and d are each independently 1 to 5. However, the material represented by formula (2) must be different from the product MQO. The material represented by formula (2) may typically have no peak in its X-ray diffraction (XRD) pattern in a diffraction angle 2θ range of 2° to 12°.

[0015] Examples of the first raw material represented by formula (2) include TiB ２ , TiB, TiC, TiN, TiO ２ , Ti ５ Si ３ , Ti ２ SbP, VO ２ , V２ O ４ , NbC, Nb ２ O ５ , MoO ２ , MoO ３ , MoS ２ , MnO ２ , Mn ３ O ４ , MnCO ３ MnO that can be used as the first raw material ２ In the XRD pattern, the material has a peak near 2θ=13° and no peak in the 2θ range of 2° or more and 12° or less.

[0016] Alternatively, or in addition to the above, a material represented by the following formula (3) (hereinafter also simply referred to as a "MAX phase" or "MAX raw material") may be used as the first raw material. ｍ A ２ X ｎ ...(3) (wherein M is as defined above, X is at least one element selected from the group consisting of C and N, n is 1 or more and 4 or less, m is greater than n and 5 or less, A ２ is at least one element selected from the group consisting of Groups 12, 13, 14, 15 and 16, and is usually a Group A element, typically Group IIIA and Group IVA, and more particularly may include at least one element selected from the group consisting of Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, S and Cd, preferably Al). The MAX phase is ｍ X ｎ (which may have a crystal lattice where each X is located in an octahedral array of M), ２ The MAX phase has a crystal structure in which layers composed of atoms are located. When m=n+1, typically, one layer of X atoms is located between each of n+1 layers of M atoms (collectively referred to as "M ｍ X ｎ layer), and the layer next to the n+1-th layer of M atoms is A ２ Atomic layer ("A ２ The MAX phase has repeating units arranged in "atomic layers." However, the MAX phase is not limited to this.

[0017] Examples of the first raw material represented by formula (3) include Ti ３ AlC ２ , Ti ３ GaC ２ , Ti ３ SiC ２ These include:

[0018] As the first raw material, the material represented by formula (2) and the material represented by formula (3) may be used together (for example, as a mixture).

[0019] As the second raw material, an ionically bondable substance having a carbon-containing group can be used. The ionically bondable substance having a carbon-containing group contains C. Examples of the ionically bondable substance include ammonium salts, phosphates, sulfates, etc.

[0020] More specifically, a quaternary ammonium salt may be used as the second raw material. Examples of quaternary ammonium salts include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH or TBAOH), benzyltrimethylammonium hydroxide, tetrabutylammonium fluoride (TBAF), tetrabutylammonium chloride (TBACl), tetrabutylammonium bromide (TBAB), tetrabutylammonium iodide (TBAI), benzyltriethylammonium chloride (BTEAC), hexadecyltrimethylammonium bromide, cetyltrimethylammonium bromide (CTAB), benzethonium chloride, benzalkonium chloride, and cetylpyridinium chloride (CPC). Among these, TMAH and TBAOH are preferred.

[0021] Alternatively, or in addition to the above, other ion-binding substances containing P and / or S, etc. may be used as the second raw material.

[0022] The protic solvent may be any solvent capable of at least partially dissolving the first and second raw materials, and may be, in particular, an aqueous solvent. Examples of the protic solvent include water, alcohol (e.g., ethanol, 1-propanol, isopropanol), and carboxylic acids (e.g., acetic acid and formic acid). The aqueous solvent may be composed of water and, optionally, a liquid substance compatible with water (e.g., a protic solvent other than water), and is preferably water.

[0023] The first and second raw materials are reacted in a protic solvent. The second raw material can be added to the protic solvent in advance. The ratio of the second raw material to the total of the protic solvent and the second raw material can be, for example, 5% by mass or more, particularly 20% by mass or more, and / or, for example, 80% by mass or less, particularly 50% by mass or less. The first raw material can be further added to the protic solvent to which the second raw material has been added, and mixed. In this mixture, a reaction to produce MQO proceeds. The temperature (reaction temperature) of the mixture (which may contain the reaction product) can be, for example, 15°C or more, particularly 40°C or more, and / or, for example, 100°C or less, particularly 80°C or less. The mixing time (reaction time) can be, for example, one day or more, particularly two days or more, and / or, for example, 10 days or less, particularly 7 days or less. Mixing can be performed, for example, by rotating a magnetic stirrer placed in a container while maintaining the reaction temperature using a hot plate stirrer and a warm water bath. However, the treatment operations and conditions (temperature, time, etc.) that can cause the reaction to proceed are not limited to those described above, and may be selected appropriately depending on the first raw material, second raw material, protic solvent, etc. that are used.

[0024] The above reaction produces MQO, which may eventually grow into MQO nanofibers and further MQO nanoflakes. While not limiting the present disclosure, the resulting MQO nanofibers may be in the form of nanoribbons extending in nanoscale widths. Alternatively, multiple MQO nanofibers (e.g., nanoribbons) may bond and / or integrate with each other to grow into two-dimensionally extending nanoflakes. Alternatively, multiple MQO nanoflakes may overlap each other (e.g., by van der Waals forces) to form stacks. While the present disclosure is not bound by any theory, the production and growth of MQO may be thought of as a bottom-up synthesis reaction.

[0025] In the present disclosure, the cross-sectional outer dimension of an MQO nanofiber refers to the shortest distance passing through the center of a cross section transverse to the longitudinal direction of the MQO nanofiber. The cross-sectional shape of an MQO nanofiber is not particularly limited, but can be approximated, for example, by a rectangle (rectangle, square, etc.) or an ellipse (flattened circle, perfect circle, etc.). When an MQO nanofiber is in the form of a nanoribbon, the cross-sectional shape can be approximated by a rectangle, and the cross-sectional outer dimension can correspond to the length of the short side of the rectangle. When an MQO nanofiber is in the form of a nanofilament, the cross-sectional shape can be approximated by a flattened circle, and the cross-sectional outer dimension can correspond to the length of the short diameter of the flattened circle.

[0026] In the present disclosure, MQO is a solid content. MQO may typically be in the form of particles (or powder).

[0027] The mixture after the reaction (also referred to as a reaction mixture) may be subjected to appropriate post-treatment, such as washing, impact (including shear force), drying (e.g., freeze-drying or heat drying), or pulverization.

[0028] The washing may be carried out using a protic solvent. The same explanation as above may be applied to the protic solvent, and the protic solvent may be washed with, for example, water or alcohol. After washing, a separation operation (centrifugation and / or decantation) may be carried out. The washing and separation operations may be repeated until the pH of the supernatant after centrifugation is, for example, 8 or less.

[0029] Optionally, instead of or in addition to the above washing, washing may be carried out using an aqueous solution of a metal salt. The metal salt may be, for example, a halide (fluoride, chloride, bromide, iodide) of an alkali metal (Li, Na, K, etc.), typically LiCl, NaCl, KCl, etc. Specifically, washing may be carried out using, for example, an aqueous solution of a metal salt having a molar concentration of 1 to 10. After washing, a separation operation (centrifugation and / or decantation) may be carried out. In this case, too, the washing and separation operations may be repeated as necessary until the pH of the supernatant after centrifugation becomes, for example, 8 or less.

[0030] Impact such as vibration and / or ultrasound may be applied during and / or after washing. This can promote the dispersion of MQO particles (e.g., nanofibers / nanoflakes, hereinafter the same). If the MQO particles are aggregated, they can be broken down. This effect is particularly pronounced when impact is applied during washing with an aqueous solution of a metal salt (it is believed that metal cations derived from the metal salt penetrate into the gaps between the aggregates and break them down). Impact can be applied using, for example, one or more of a handshake, an automatic shaker, a mechanical shaker, a vortex mixer, a homogenizer, an ultrasonic bath, etc.

[0031] Since the MQO particles are a solid component, a separation operation can be carried out at any appropriate time to remove unnecessary liquid components, if any. As a final separation operation, for example, a drying operation, typically freeze-drying or thermal drying, may be carried out. Freeze-drying can be carried out, for example, by freezing a mixture containing the MQO particles and a liquid component at any appropriate temperature (e.g., −40° C.) and then drying under reduced pressure. Thermal drying can be carried out, for example, by drying a mixture containing the MQO particles and a liquid component at a temperature of 25° C. or higher (e.g., 200° C. or lower) under atmospheric pressure or under reduced pressure. Pulverization can be carried out using, for example, a mortar and pestle combination, an IKA mill, or the like, without particular limitation. Pulverization may also be carried out after drying.

[0032] In order to obtain a material containing MQO (a predetermined nanofiber and / or two-dimensional substance, typically MQO particles; hereinafter, this may be referred to as the "MQO-containing material") with higher purity, it is preferable to repeat washing and centrifugation multiple times and recover the supernatant after the final centrifugation. This supernatant can be used as is, or after being appropriately diluted with a liquid medium, or mixed with a liquid medium after drying to form a slurry containing MQO particles. This slurry can be used to produce a film, which can then be used as the antibacterial material of this embodiment.

[0033] As a result, MQO particles can be obtained as an MQO-containing material. MQO is represented by formula (1), but the MQO-containing material (typically, MQO particles) does not necessarily have to consist solely of the constituent elements of formula (1). While not limiting the present disclosure, the MQO-containing material may optionally have at least one type of modification or terminal T present on its surface selected from the group consisting of hydroxyl groups, chlorine atoms, oxygen atoms, hydrogen atoms, and nitrogen atoms. Furthermore, the MQO-containing material (typically, MQO particles) may have two or more layers, and at least one type selected from the group consisting of ammonium ions (e.g., quaternary ammonium cations) and metal cations (e.g., alkali metal ions, alkaline earth metal ions) may be present between these layers.

[0034] The particle size of the MQO particles may be, for example, 0.01 nm or more, in particular 0.1 nm or more, or even 1 nm or more, and / or may be, for example, less than 1000 nm, in particular 100 nm or less, or even 50 nm or less. Such particles may also be referred to as nanoparticles.

[0035] The particle form of MQO is nanofibers and / or two-dimensional materials. The two-dimensional materials include one or more of nanoflakes and stacks of nanoflakes. In this embodiment, the two-dimensional materials are not limited to only nanoflakes and stacks of nanoflakes.

[0036] Nanofibers may also be referred to as nanowires. In the present disclosure, "nanofiber" refers to a solid object extending in the longitudinal direction, the cross-sectional dimensions of which perpendicular to the longitudinal direction (cross-sectional external dimensions) are on the nano-order (i.e., 1 nm or more and less than 1000 nm) or even smaller, sub-nano-order (less than 1 nm, for example, 0.1 nm or more and less than 1 nm). The longitudinal length of a nanofiber is not limited to the nano-order (i.e., 1 nm or more and less than 1000 nm), but may also be on the micron order (1 μm or more and less than 1000 μm). The cross-sectional external dimensions of a nanofiber may be, for example, 0.1 nm or more, particularly 1 nm or more, and may be, for example, 100 nm or less, particularly 50 nm or less, and preferably 15 nm or less.

[0037] In the present disclosure, the term "two-dimensional material" refers to a solid object having a two-dimensionally extending surface (also referred to as a plane or two-dimensional sheet surface) and a thickness that is relatively small compared to the maximum dimension of the surface (which may correspond to the "in-plane dimension" of a particle), with the thickness being on the nano-order (i.e., 1 nm or more but less than 1000 nm) or even smaller, on the sub-nano-order (less than 1 nm, for example, 0.1 nm or more but less than 1 nm). The in-plane dimension is not limited to the nano-order (i.e., 1 nm or more but less than 1000 nm) and may be on the micron-order (1 μm or more but less than 1000 μm). As described above, two-dimensional materials include one or more of nanoflakes and stacks of nanoflakes. Nanoflakes may also be referred to as nanosheets or two-dimensional (nano)sheets. The thickness of one layer of nanoflakes may be, for example, 0.01 nm or more, particularly 0.8 nm or more, and may be, for example, 20 nm or less, particularly 3 nm or less. The in-plane dimensions of the nanoflakes may be, for example, 0.1 μm or more, in particular 1 μm or more, and may be, for example, 200 μm or less, in particular 40 μm or less. The nanoflakes may be composed of an aggregate of nanofibers.

[0038] The stack of nanoflakes may also be referred to as a multi-layer MQO. The distance (interlayer distance or gap size) between two adjacent nanoflakes (or two adjacent layers of MQO) is not particularly limited.

[0039] Each of the above dimensions can be determined as a number-average dimension (number average of at least 40 dimensions) based on a photograph observed with a scanning electron microscope (SEM), a transmission electron microscope (TEM), or an atomic force microscope (AFM) (after processing by a method such as focused ion beam (FIB) if necessary), or as a distance in real space calculated from the position in reciprocal lattice space of the (002) plane measured by X-ray diffraction (XRD).

[0040] However, it should be noted that in the present disclosure, the MQO is not limited to the above forms and may have any suitable form.

[0041] Research by the present inventors has revealed that MQO-containing materials have excellent antibacterial properties. The antibacterial material of this embodiment contains an MQO-containing material and therefore has excellent antibacterial properties. It should be noted that the antibacterial material of this embodiment may have any appropriate form as long as it contains an MQO-containing material. One aspect of the antibacterial material of this embodiment is that it is composed of a material containing nanofibers and / or two-dimensional substances represented by a specific formula. The term "composed of" is intended to include aspects in which the material is essentially composed of a material containing nanofibers and / or two-dimensional substances represented by a specific formula (which may include other objects and impurities that may inevitably be mixed in), as well as aspects in which the material is composed solely of the nanofibers and / or two-dimensional substances. Another aspect of the antibacterial material of this embodiment is that it contains, in addition to the material containing nanofibers and / or two-dimensional substances represented by a specific formula, other materials such as a liquid medium (described below), a polymer (described below), and additives suitable for antibacterial materials.

[0042] The MQO-containing material may typically have a peak in an X-ray diffraction (XRD) pattern where the diffraction angle 2θ is in the range of 2° to 12° inclusive. Although the present disclosure is not bound by any theory, it is believed that the MQO-containing material having a peak in an XRD pattern where 2θ is in the range of 2° to 12° inclusive means that the MQO has a crystal structure different from that of well-known metal oxides.

[0043] In the present disclosure, an XRD pattern is a pattern (the vertical axis represents intensity and the horizontal axis represents 2θ) obtained by scanning in the θ-axis direction with an XRD analyzer using CuKα radiation (approximately 1.54 Å) as characteristic X-rays, and may also be referred to as an “XRD profile.” Peaks in an XRD pattern can be identified visually or by using software used with the XRD analyzer.

[0044] Although this embodiment is not limited to this embodiment, the material of this embodiment (more specifically, MQO) has a Raman shift of at least 275 to 295 cm in a Raman spectrum using a laser with a wavelength of 514 nm. －１ , 435-455cm －１, and 665-745 cm －１ It may have a peak at the position

[0045] Although this embodiment is not limited thereto, the material of this embodiment (more specifically, MQO) has, for example, an anatase type or a lepidocrocite type crystal structure, or a mixture of these. More preferably, it has a lepidocrocite type crystal structure.

[0046] Although this embodiment is not limited to this embodiment, the material of this embodiment (more specifically, MQO) has a Raman shift of at least 275 to 295 cm in a Raman spectrum using a laser with a wavelength of 514 nm. －１ , 435-455cm －１ , and 665-745 cm －１ and when the intensities of the respective peaks are X, Y, and Z, X is the largest.

[0047] Although this embodiment is not limited thereto, more preferably, the material of this embodiment (more specifically, MQO) has a Raman shift of at least 180 to 200 cm in a Raman spectrum using a laser with a wavelength of 514 nm. －１ , 275-295cm －１ , 375-395cm －１ , 435-455cm －１ , and 665-745 cm －１ and when the intensities of the respective peaks are V, X, Y, Z, and W, X is the largest.

[0048] In this disclosure, the Raman spectrum is measured with a Raman spectrometer using a 514 nm laser as an excitation light source (the vertical axis represents intensity, and the horizontal axis represents Raman shift). Peaks in the Raman spectrum can be identified visually or by using software used with the Raman spectrometer.

[0049] The MQO-containing material may also contain unreacted first and / or second raw materials as impurities, and may also contain substances derived from the first, second, and / or protic solvents. For example, when a quaternary ammonium salt is used as the second raw material, N may be present (residual) in any form in the MQO-containing material. While not limiting this embodiment, the MQO-containing material may contain ammonium ions or tetramethylammonium ions. Furthermore, when a MAX raw material is used as the first raw material, the MQO-containing material may contain a relatively small amount of residual A atoms, for example, 10% by mass or less relative to the original A atoms, in the present disclosure. The amount of residual A atoms may preferably be 8% by mass or less, more preferably 6% by mass or less. However, even if the amount of residual A atoms exceeds 10% by mass, this may not be a problem depending on the use conditions, etc.

[0050] The proportion of the MQO-containing material (nanofibers and / or two-dimensional material) contained in the antibacterial material is not limited as long as the desired antibacterial properties are exhibited. The form of the antibacterial material according to this embodiment is not limited, but the antibacterial material may be in the form of a fluid material or a solid material. When the antibacterial material is a fluid material such as a slurry or paste, the content of the MQO-containing material may be 0.01 mass% or more and 50 mass% or less in terms of the proportion of the antibacterial material. When the antibacterial material is a solid material such as a film, the content of the material containing MQO may be 0.01 mass% or more. When the antibacterial material is a solid material such as a film, it may be composed solely of the MQO-containing material.

[0051] When the antibacterial material is a fluid material, examples thereof include a slurry, paste, or the like in which an MQO-containing material (e.g., MQO particles) is dispersed in a liquid medium. Regardless of the fluid material, the MQO particles according to this embodiment have high dispersibility and are well dispersed in the liquid medium without agglomeration. The liquid medium may be water or an aqueous polymer solution containing a water-soluble polymer, for example, in an amount greater than 0% by mass and not greater than 20% by mass, preferably not greater than 10% by mass, of the total liquid medium. Examples of the water-soluble polymer include water-soluble polyurethane, water-soluble polyester, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, poly(N-vinylacetamide), and acrylic acid-based water-soluble polymers.

[0052] The polymer preferably has at least one hydrogen acceptor selected from the group consisting of fluorine atoms, chlorine atoms, oxygen atoms, and nitrogen atoms, and a hydroxyl group and / or a secondary amino group as a hydrogen donor. The polymer preferably has a negative zeta potential.

[0053] Examples of the polymer include polyethyleneimine (PEI), polypyrrole (PPy), polyaniline (PANI), and polyimide (PI) containing a secondary amino group such as flame-retardant polyimide; and examples of polymers having an amide bond (-NHCO-) ​​or a urethane bond include polyamideimide (PAI), polyacrylamide (PMA), nylon (polyamide-based resin), DNA (deoxyribonucleic acid), acetanilide, acetaminophen, and silicone resin. Among these, polymers having an amide bond or a urethane bond are preferred. Polyurethane is even more preferred as the polymer having an amide bond or a urethane bond, and polyether / carbonate-based polyurethane is even more preferred.

[0054] A polar organic solvent may be used as the liquid medium. When a polar organic solvent is used, the polar organic solvent may be mixed with water. Examples of the polar organic solvent include alcohols, polyhydric alcohols, ketones, ethers, esters, and aprotic polar solvents. Examples of alcohols include methanol, ethanol, propanol, and butanol. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, and glycerin. Examples of ketones include acetone and methyl ethyl ketone (MEK). Examples of ethers include diethyl ether and tetrahydrofuran. Examples of esters include ethyl acetate and butyl acetate. Examples of aprotic polar solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and 1-methyl-2-pyrrolidone. The polar organic solvent is preferably an alcohol.

[0055] When the antibacterial material is in the form of a solid material containing the MQO-containing material, the antibacterial material may contain a polymer in addition to the MQO-containing material. Examples of the polymer include hydrophilic polymers (including hydrophobic polymers that are hydrophilic due to the addition of a hydrophilic auxiliary agent, and hydrophobic polymers whose surfaces have been hydrophilized), and examples of the hydrophilic polymer include one or more selected from the group consisting of polysulfone, cellulose acetate, regenerated cellulose, polyethersulfone, water-soluble polyurethane, polyvinyl alcohol, sodium alginate, acrylic acid-based water-soluble polymers, polyacrylamide, polyaniline sulfonic acid, and nylon.

[0056] The polymer preferably has at least one hydrogen acceptor selected from the group consisting of fluorine atoms, chlorine atoms, oxygen atoms, and nitrogen atoms, and a hydroxyl group and / or a secondary amino group as a hydrogen donor. The polymer preferably has a negative zeta potential. Examples of the polymer include polyethyleneimine (PEI), polypyrrole (PPy), polyaniline (PANI), and polyimides (PI) containing secondary amino groups such as flame-retardant polyimides. Examples of polymers having an amide bond (-NHCO-) ​​or a urethane bond include polyamideimide (PAI), polyacrylamide (PMA), nylon (a polyamide-based resin), DNA (deoxyribonucleic acid), acetanilide, and acetaminophen. Among these, polymers having an amide bond or a urethane bond are preferred. Polyurethane is even more preferred as the polymer having an amide bond or a urethane bond, and polyether / carbonate-based polyurethanes are even more preferred.

[0057] Examples of the polymer include silicone resin, fluororesin, acrylic resin, nylon, polyethylene, polypropylene, etc., in addition to the above-mentioned polymer having a secondary amino group.

[0058] The proportion of the polymer in the antibacterial material (solid material) can be determined in consideration of the desired properties such as antibacterial properties, etc. The proportion of the polymer in the antibacterial material can be, for example, 1% by mass or more and 50% by mass or less.

[0059] The MQO-containing material according to this embodiment has high dispersibility, and is therefore well mixed with the polymer, resulting in a polymer composite in which the MQO-containing material is well dispersed without aggregation. The MQO-containing material and polymer can be stirred using a dispersing device such as a homogenizer, a propeller stirrer, a thin film rotary stirrer, a planetary mixer, a mechanical shaker, or a vortex mixer.

[0060] The antibacterial material of this embodiment may be, for example, in the form of a film. The film-like antibacterial material can be formed, for example, using a slurry containing the MQO particles or a slurry that is a mixture of the MQO particles and a polymer. The film-like antibacterial material can be formed, for example, by applying the slurry that is a mixture of the MQO particles and a polymer to a substrate (e.g., a substrate). However, the application method is not limited. Examples of the application method include spray application using a nozzle such as a one-fluid nozzle, a two-fluid nozzle, or an airbrush; slit coating using a table coater, comma coater, or bar coater; screen printing; metal mask printing; and application methods such as spin coating, dipping, and dripping. The application and drying may be repeated multiple times as necessary until a film of the desired thickness is obtained. Drying and curing may be performed, for example, at a temperature of 400°C or less using an atmospheric pressure oven or a vacuum oven.

[0061] While the present disclosure is not bound by any theory, it is believed that one of the reasons for the high dispersibility of the MQO particles according to this embodiment is the large absolute value of the zeta potential. While the present embodiment is not bound by any theory, it is believed that the MQO particles themselves have a large absolute value of zeta potential, and that dispersion is maintained by electrostatic repulsion. The absolute value of the zeta potential, when measured by the following method, can be, for example, 1 or more, and preferably 10 or more. To measure the zeta potential, a dispersion liquid is used, which uses ion-exchanged water as a dispersion medium, is adjusted to a concentration of MQO particles in the range of 0.01 to 0.1 mass%, and is permeated with a vortex mixer for 5 minutes. Using this dispersion liquid, measurements are performed under atmospheric pressure using a zeta potential measurement device (device name: Zetasizer Nano-ZS, Malvern Panalytical, Malvern, U.K.).

[0062] Although the antimicrobial material according to one embodiment of the present disclosure has been described above in detail, various modifications of the present disclosure are possible. Note that the material according to the present disclosure may be manufactured by a method different from that described in the above embodiment.

[0063] When the composite material of this embodiment is in the form of a film, a film with high film strength can be obtained. As shown in FIG. 1, TiO, which has conventionally been used as a filler, is ２ The polymer composite obtained by mixing the resin 1 and the resin 3 without adding a dispersant and then applying the mixture to a PET substrate 5 contains TiO ２ The aggregated regions 1 are likely to form aggregated regions 7, surrounded by dashed lines (Figure 1, left). When the above polymer composite is pulled in the direction of the black arrow, for example, for measuring film strength (tensile testing), fracture failure is likely to occur starting from the aggregated regions 7, as shown in Figure 1, right. In contrast, as shown schematically in Figure 2, a polymer composite obtained by mixing a material 9 containing a predetermined nanofiber and / or two-dimensional material with a resin 3 without adding a dispersant and then applying the mixture to a PET substrate 5 allows the material 9 to be dispersed without agglomeration. While adding a dispersant during mixing with the resin shortens the service life due to degradation of the dispersant, the composite material of this embodiment does not encounter such a problem. As a result, when the film is pulled in the direction of the black arrow, for example, for measuring film strength (tensile testing), fracture is unlikely to occur and the film exhibits high strength.

[0064] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and can be practiced with appropriate modifications within the scope of the above-mentioned and below-mentioned aims, and all such modifications are included in the technical scope of the present invention.

[0065] Example 1 Preparation of a Slurry Containing TiCO First, titanium diboride (TiB ２1 g of tetramethylammonium hydroxide (TMAH) (manufactured by Alfa Aesar) and 10 mL of a 25% by weight aqueous solution (manufactured by Alfa Aesar) of tetramethylammonium hydroxide (TMAH) were added. A stirrer tip with a length (35 mm) approximately the same size as the inner diameter of the circular bottom of the container was placed therein. The container was maintained at 80°C in an oil bath, and the mixture in the container was stirred with the stirrer tip for 120 hours, allowing the reaction to proceed. The reaction mixture in the container was then transferred to a centrifuge tube. The solids were allowed to settle by centrifugation at 3500 G for 5 minutes using a centrifuge. (i) After centrifugation, the supernatant was discarded, (ii) 40 mL of ethanol (manufactured by Fisher Chemical) was added to the remaining sediment in the centrifuge tube, and the resulting mixture was dispersed using a vortex mixer for 5 minutes (reslurry), and (iii) centrifuged under the same conditions as above. These steps (i) to (iii) were repeated until the pH of the supernatant became 8 or less. After repeating the steps three times, the pH of the supernatant became 8 or less, so the supernatant was discarded and the repeating operation was terminated. 40 mL of pure water was added to the remaining sediment in the centrifuge tube, and the mixture was shaken and stirred for 5 minutes using a vortex mixer. Thereafter, centrifugation was performed using a centrifuge at 3500 G for 30 minutes, and the supernatant was collected as a sample slurry. The obtained sample slurry corresponds to a slurry containing TiCO as MQO.

[0066] (Raman Spectroscopic Analysis) Using the TiCO slurry, a Raman spectrum was obtained by measuring with a Raman spectrometer (manufactured by Renishaw, product number: InVia) using a laser beam with a wavelength of 514 nm as an excitation light source. An example of the measurement results is shown in FIG. 3. From FIG. 3, it can be seen that the Raman shift is 275 to 295 cm －１ , 435-455cm －１ , and 665-745 cm －１ 3, which indicates that the compound has a lepidocrocite-type crystal structure. －１ , 275-295cm －１ , 375-395cm －１ , 435-455cm －１ , and 665-745 cm －１It can also be seen that when the intensities of the respective peaks are V, X, Y, Z, and W, X is the largest.

[0067] [Film Preparation] 1 mL of the sample slurry prepared above was taken and mixed with 20 mL of pure water, and then shaken for 5 minutes using an automatic shaker. The resulting mixture was suction filtered overnight using a Nutsche filter. A membrane filter (Durapore, pore size 0.22 μm, manufactured by Merck Ltd.) was used for the suction filtration. After suction filtration, the precursor film on the filter was dried overnight at 80°C in a vacuum oven, and the filter was removed to obtain a film (freestanding film).

[0068] [Analysis] The film (freestanding film) obtained in the same manner as above was analyzed by X-ray photoelectron spectroscopy (XPS). Peaks corresponding to Ti2p, C1s, O1s, and N1s were observed in the obtained XPS spectrum, and therefore Ti, C, O, and N were detected. Since N is thought to be a residue of the raw material TMAH, the material of the freestanding film is thought to be composed of Ti, C, and O.

[0069] Furthermore, the XRD profile of the film (freestanding film) obtained in the same manner as above was measured using an XRD device (MiniFlex, manufactured by Rigaku Corporation) (characteristic X-rays: CuKα=1.54 Å). The obtained XRD pattern is shown in Figure 4. As can be seen from Figure 4, this material had a peak for the (001) plane at 2θ=7.9° and a peak for the (002) plane at 2θ=15.6°. This indicates that this material is a nanomaterial.

[0070] The shape of the TiCO was observed by SEM. Specifically, the sample slurry prepared above was diluted 1000 times and dropped onto an Al porous substrate. Pt / Pd deposition (40 mA, 30 s) was performed, and SEM observation revealed that nanofibers with a width of 20 nm were obtained.

[0071] Furthermore, the zeta potential of the slurry was measured and found to be -80 mV, which was a larger absolute value than the -0.5 mV of the zeta potential of conventional titanium dioxide (P-25). Next, the zeta potential of the polymer was measured and found to be -35.5 mV for polyurethane (Rezamin D-4080 (polyether / carbonate type) manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.).

[0072] [Evaluation of antibacterial properties] The sample slurry prepared above was diluted to 0.5 wt % to prepare a specimen. The following two types of bacteria were tested: Test bacteria (1) Escherichia coli NBRC 3972 (Escherichia coli) Test bacteria (2) Staphylococcus aureus subsp. aureus NBRC 12732 (Staphylococcus aureus)

[0073] Test bacteria (1) were cultured in LB medium at 35°C ± 1°C for 18 to 24 hours, and the culture solution was centrifuged (4000 x g, 10 minutes). The cells were then suspended in purified water. This centrifugation and washing procedure was repeated three times, and the number of bacteria was then measured using purified water. ７ ~10 ８ The test bacterial solution was prepared so that the concentration was 1 / mL, and this was used as the test bacterial solution. 0.1 mL of the test bacterial solution was then inoculated into 10 mL of the sample (0.5 wt% TiCO aqueous solution). The viable bacterial counts after 4 and 24 hours of storage (35°C ± 1°C, horizontal shaking (approximately 150 r / min)) were measured on SCDLP agar medium (Shioya MS Co., Ltd.) using the pour plate culture method (35°C ± 1°C, 2 days). The viable bacterial counts for test bacteria (2) were also measured in the same manner as for test bacteria (1). The results are shown in Figure 5 for test bacteria (1) and Figure 6 for test bacteria (2).

[0074] As can be seen from Figure 5, in the case of test bacteria (1), when TiCO(MQO) was included, the number of test bacteria decreased significantly over time compared to when TiCO(MQO) was not included. Also, as can be seen from Figure 6, in the case of test bacteria (2), even when TiCO was not included, the number of test bacteria tended to decrease over time, but when TiCO was included, the number of test bacteria decreased even more significantly. These results demonstrate that the antibacterial material of this embodiment containing TiCO has excellent antibacterial properties.

[0075] [Evaluation of Dispersibility] The present inventors separately conducted a test using titanium dioxide (TiO ２ ) aqueous dispersion (titanium dioxide concentration: 2% by mass), titanium dioxide (TiO ２ An aqueous polyurethane dispersion of TiCO(MQO) particles (concentration of titanium dioxide: 1% by mass, concentration of polyurethane: 1% by mass) according to the present embodiment was placed in a glass container and allowed to stand. The bottoms of the glass containers were then visually inspected after being left for four days. The photographs are shown in Figures 7 to 9. A circular white precipitate was observed in the center of the photograph in Figure 7, and a circular white precipitate was observed in the center of the photograph in Figure 8. As is clear from the photographs in Figures 7 and 8, titanium dioxide had precipitated at the bottom of the glass container. In contrast, as shown in the photograph in Figure 9, no precipitation of TiCO particles was observed in the aqueous polyurethane dispersion of TiCO(MQO) particles according to the present embodiment, even after four days (note that the white area at the top of the photograph in Figure 9 is due to the background being mixed in and not a precipitate). It is believed that the high dispersibility of the TiCO particles according to the present embodiment contributes to the excellent antibacterial properties described above.

[0076] Example 2 TiCO / Polyurethane Composite Film [Preparation of Resin Slurry and Mixing of Resin Slurry with TiCO-Containing Slurry] Polyurethane (Rezamin D-4080 (polyether / carbonate type) manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) and pure water were mixed in a ratio of 1:9 and stirred for 5 minutes with a vortex mixer to obtain a resin slurry.

[0077] The resin slurry, pure water, and a slurry containing TiCO were mixed so as to obtain a TiCO / polyurethane composite material in which the ratio of polyurethane to TiCO (after film formation and drying) was 30 mass %. The mixture was stirred for 5 minutes with a vortex mixer to obtain a mixed slurry of TiCO and resin.

[0078] [Preparation of TiCO / Polyurethane Composite Film (1) Spray Coating] The TiCO / resin mixed slurry prepared above was spray coated onto a PET substrate using an airbrush with a spray nozzle. The spray irradiation and drying with a dryer were repeated until the film thickness of the TiCO / polyurethane composite material reached 5 μm. After coating, the film was dried in a normal pressure oven at 80°C for about 30 minutes to obtain a TiCO / polyurethane composite film.

[0079] [Preparation of TiCO / Polyurethane Composite Film (2) Suction Filtration] The TiCO / resin mixed slurry prepared above was subjected to suction filtration overnight using a Nutsche filter. A membrane filter (Durapore, pore size 0.22 μm, manufactured by Merck Ltd.) was used as the suction filtration filter. After suction filtration, the precursor film on the filter was dried overnight at 80°C in a vacuum oven, and the filter was removed to obtain a TiCO / polyurethane composite film (freestanding film).

[0080] [Comparative Example 2: TiO ２ / Polyurethane composite film] The TiCO of Example 2 was replaced with TiO ２ The same procedure as in Example 2 was repeated except that the TiO ２ and resin mixed slurry, and TiO by spray coating ２ A / polyurethane composite film was obtained.

[0081] [Evaluation] The composite material membranes of Example 2 and Comparative Example 2 were used to carry out the following evaluations.

[0082] [Measurement of XRD Pattern of TiCO / Polyurethane Composite Film] The TiCO / polyurethane composite film (freestanding film) obtained by the above [Preparation of TiCO / Polyurethane Composite Film (2) Suction Filtration] was used to measure the XRD pattern (characteristic X-ray: CuKα = 1.54 Å) using an XRD device (MiniFlex, manufactured by Rigaku Corporation). The obtained XRD pattern is shown in FIG. 10. FIG. 11 shows a diagram in which this FIG. 10 and the XRD profile of FIG. 4 are superimposed. As can be seen from FIG. 11, the TiCO / polyurethane composite material had a (001) plane peak at 2θ = 7.7° and a (002) plane peak at 2θ = 15.5°. As shown in FIG. 11, the peak positions were not significantly different from those of the TiCO film alone, indicating that this TiCO mixed with the resin still retains a periodic structure in the thickness direction.

[0083] [Evaluation of Film Strength] The TiCO / polyurethane composite film obtained by the above [Preparation of TiCO / polyurethane Composite Film (1) Spray Coating] and the TiO ２ A tape peel test was performed using the composite film / polyurethane composite film to measure the strength of the composite film as follows: Specifically, adhesive tape (3M, 6122MP Scotch® Magic™ TAPE, ¾ inch wide) was applied to a portion of the upper surface of the composite film formed on the PET substrate, and then peeled off to visually check for cohesive failure of the composite film, i.e., the presence or absence of internal separation due to transfer of a portion of the composite film to the adhesive surface of the tape.

[0084] As a result, no cohesive failure was observed in the TiCO / polyurethane composite film. On the other hand, cohesive failure was observed in the titanium dioxide / polyurethane composite film. This is because titanium dioxide (TiO ２ ) in aqueous dispersions, resulting in a poor dispersibility of titanium dioxide (TiO ２) was poorly dispersed, which is thought to have resulted in titanium dioxide easily agglomerating and resulting in poor strength as shown in Figure 1. On the other hand, in the TiCO / polyurethane composite film, TiCO was dispersed as shown in Figure 2, which is thought to have made it less likely to break when pulled and to have exhibited high strength. The high dispersibility of the TiCO particles was confirmed in the dispersibility evaluation mentioned above.

[0085] [Evaluation of antibacterial properties of film] Using the TiCO / polyurethane composite film (film) obtained in the above [Preparation of TiCO / polyurethane composite film (1) Spray coating], the antibacterial properties of the film were evaluated according to "5. Test method" in JIS Z 2801:2012 "Antibacterial processed products - Antibacterial test method / antibacterial effect". The test conditions were as follows. Test strains: Test bacteria (1) Escherichia coli NBRC 3972 (Escherichia coli) Test bacteria (2) Staphylococcus aureus subsp. aureus NBRC 12732 (Staphylococcus aureus) Viable cell count in test bacteria solution: (1) 1.1 x 10 ６ / mL (2) 2.3×10 ６ / mL Inoculation amount of test bacterial solution: 0.1 mL Test area: 50 x 40 mm square Covering film: polyethylene film Test temperature: 35°C Test time: 24 hours Specimen: (Specimen A) TiCO / polyurethane composite film prepared by spray coating on a PET substrate, (Specimen B) glass plate

[0086] The test procedure is as specified in JIS and is outlined below: 1) Cultivation of bacterial species 2) Preparation of bacterial suspension by dilution or other procedures 3) Inoculation of the test bacterial solution into the specimen and protection with a covering film (hold at 35°C for 24 hours) 4) Recovering bacteria from the specimen and measuring the viable cell count

[0087] As a result of measuring the viable bacteria count, a 1 cm test piece of the TiCO / polyurethane composite film (specimen A) ２ The number of viable bacteria per test piece was <0.83 for both test bacteria (1) and test bacteria (2), which was so small that it could not be detected. On the other hand, the number of viable bacteria per test piece was <0.83 for both test bacteria (1) and test bacteria (2), which was so small that it could not be detected. ２ The number of viable bacteria per test was 4.5 x 10 for test bacteria (1) and test bacteria (2).４ , 1.5 × 10 ５ This indicates that TiCO also exhibits antibacterial properties as a polyurethane composite material.

[0088] This application claims priority to U.S. Application No. 63 / 609,373, filed December 13, 2023, the entire contents of which are incorporated herein by reference.

[0089] 1 TiO ２ (Filler) 3 Resin 5 PET substrate 7 Aggregation portion 9 Material containing predetermined nanofibers and / or two-dimensional substances

Claims

1. The formula: MQ ａ O ｂ (wherein M is at least one element selected from the group consisting of groups 3, 4, 5, 6, and 7; Q is at least one element selected from the group consisting of groups 12, 13, 14, 15, and 16 (excluding O); a is 0 or more and 2 or less; and b is 0 or more and 2 or less.

2. The antibacterial material according to claim 1, which has a peak in an X-ray diffraction pattern at a diffraction angle 2θ in the range of 2° or more and 12° or less.

3. In the Raman spectrum using a laser with a wavelength of 514 nm, the Raman shift is 275 to 295 cm －１ , 435-455cm －１ , and 665-745 cm －１ The antibacterial material according to claim 1 or 2, having a peak at the position 4. The antibacterial material according to any one of claims 1 to 3, which has a crystal structure of anatase type, lepidocrocite type, or a mixture of these.

5. The antibacterial material according to any one of claims 1 to 4, having a lepidocrocite type crystal structure.

6. In the Raman spectrum using a laser with a wavelength of 514 nm, the Raman shift is at least 180 to 200 cm －１ , 275-295cm －１ , 375-395cm －１ , 435-455cm －１ , and 665-745 cm －１ The antibacterial material according to any one of claims 1 to 5, wherein, when the intensities of the respective peaks are V, X, Y, Z, and W, X is the largest.

7. The antibacterial material according to any one of claims 1 to 6, wherein M is Ti, Q is C, and a is not 0.

8. The antimicrobial material according to any one of claims 1 to 7, comprising a polymer.

9. The antibacterial material according to claim 8, wherein the polymer accounts for 5% by mass or more of the antibacterial material.

10. The antibacterial material according to any one of claims 1 to 9, which is in the form of a film.

11. The antibacterial material according to any one of claims 1 to 10, comprising water or an aqueous polymer solution, the nanofibers and / or two-dimensional material being dispersed in the water or aqueous polymer solution.

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