Antifungal materials and products

Abstract

The present invention provides an antifungal component that suppresses the growth of mold, and a product containing this antifungal component. [Solution] True surface area (m²) measured by krypton adsorption method 2 ) is the geometric surface area (m 2 An antifungal member having a surface whose roughness index, obtained by dividing by ), is 4.0 or higher.

Description

[Technical Field]

[0001] This invention relates to antifungal members and products. [Background technology]

[0002] Various methods are known for roughening the surface of components made of metal or other materials to form fine three-dimensional structures. Patent Document 1 reports that when a roughened surface satisfies certain conditions, it exhibits an effect of suppressing the growth of bacteria or viruses. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2023 / 013557 [Overview of the project] [Problems that the invention aims to solve]

[0004] Patent Document 1 describes that the growth of prokaryotes such as bacteria and viruses that lack a cell membrane is suppressed on roughened surfaces, but it does not suggest using roughened surfaces to suppress the growth of eukaryotes such as fungi. In view of the above circumstances, one embodiment of the present disclosure aims to provide an antifungal member that suppresses the growth of mold, and a product containing this antifungal member. [Means for solving the problem]

[0005] The following embodiments are included as means for solving the above problems. <1> True surface area (m²) measured by krypton adsorption method 2 ) is the geometric surface area (m 2 An antifungal member having a surface whose roughness index, obtained by dividing by ), is 4.0 or higher. <2> To suppress the growth of mold on the aforementioned surface, <1> The antifungal material described in [the document]. <3> Used in environments where condensation may occur on the aforementioned surface, <1> or <2> The antifungal material described in [the document]. <4> The portion corresponding to the aforementioned surface includes metal. <1> ~ <3> The antifungal material described in any one of the items. <5> The portion corresponding to the aforementioned surface includes resin. <1> ~ <3> The antifungal material described in any one of the items. <6> <1> ~ <5> A product comprising an antifungal component as described in any one of the items, and selected from the group consisting of air conditioning equipment, humidifiers, ventilation equipment, dust collectors, and building components. [Effects of the Invention]

[0006] According to one embodiment of the present disclosure, an antifungal member that inhibits the growth of mold, and a product containing this antifungal member are provided.

[0007] In this disclosure, a numerical range indicated using "~" represents a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages, or with the values ​​shown in the examples. In this disclosure, the amount of each component in the material means the total amount of multiple substances present in the material, unless otherwise specified, if there are multiple substances corresponding to each component in the material.

[0008] In this disclosure, "anti-mold component" means a component that exhibits anti-mold properties. In this disclosure, "anti-mold properties" include the ability to kill mold or inhibit its growth. In this disclosure, "mold" refers to a microorganism composed of filamentous cells called hyphae.

[0009] <First Embodiment> The first embodiment of this disclosure is the true surface area (m²) measured by the krypton adsorption method. 2 ) is the geometric surface area (m 2) It is a mold-resistant member having a surface with a roughness index of 4.0 or more obtained by dividing by

[0010] The mold-resistant member of this embodiment exhibits a mold-resistant action by having a surface with a roughness index of 4.0 or more. The mechanism by which a mold-resistant member having a surface with a roughness index of 4.0 or more exhibits mold-resistant performance is speculated as follows, for example. On the surface of the mold-resistant member with a roughness index of 4.0 or more (hereinafter also referred to as a roughened surface), a fine three-dimensional structure on the order of nanometers to micrometers is formed. It is considered that this fine three-dimensional structure has some action to inhibit the elongation of hyphae from spores adhering to the roughened surface of the mold-resistant member.

[0011] The mold-resistant member of this embodiment may be used, for example, in an environment where dew condensation may occur on the surface of the mold-resistant member. In an environment where dew condensation may occur on the surface of the mold-resistant member, mold spores adhere to the surface of the mold-resistant member and mold is likely to grow. Therefore, from the viewpoint of effectively exhibiting mold-resistant performance, it is preferable to use the mold-resistant member in an environment where dew condensation may occur on its surface.

[0012] The environment where dew condensation may occur on the surface of the mold-resistant member is not particularly limited. Specific examples of the environment include the inside of air conditioners, humidifiers, ventilators, dust collectors, window frames, medical and pharmaceutical related (for example, medical pads, surgical instruments, caps for medicine bottles, dental materials, etc.); housing related (for example, doorknobs, handrails, etc.); food and cooking related (for example, dishes, cooking utensils, sinks, faucets, serving trays); infrastructure related (for example, water treatment, pipes used in factory facilities, liquid storage containers, etc.); automobile related (for example, doorknobs, etc.); miscellaneous goods related (for example, pen holders, rulers, sharp pencils, calculators, etc.); IT related (for example, the casings of personal computers, smartphones, etc.); and entertainment related (for example, medals used in gaming machines, etc.).

[0013] The antifungal material has a true surface area (m²) measured by the krypton adsorption method. 2 ) is the geometric surface area (m 2 The surface (roughened surface) has a roughness index of 4.0 or higher obtained by dividing by ). From the viewpoint of effectively exhibiting the antifungal properties of the antifungal material, the roughness index of the roughened surface is preferably 5.0 or higher, more preferably 7.0 or higher, and even more preferably 10.0 or higher. There is no particular upper limit to the roughness index of the roughened surface, but from the viewpoint of the persistence of the antifungal performance, it may be 150.0 or less, 125.0 or less, or 110.0 or less.

[0014] In this disclosure, an antifungal member in which the roughness index of at least a portion of the roughened surface is within the above-mentioned range corresponds to "an antifungal member in which the roughness index of the roughened surface is within the above-mentioned range." From the viewpoint of effectively exhibiting the antifungal properties of the antifungal material, the roughness index of 50% or more, 80% or more, or 90% or more of the roughened surface may be within the range described above.

[0015] The true surface area used to calculate the roughness index is the specific surface area (m²) of the sample obtained by the krypton adsorption method (i.e., the antifungal material). 2 This value is calculated by multiplying the mass of the sample by the value of (g). The specific surface area is determined by measuring the adsorption isotherm using the krypton adsorption method at liquid nitrogen temperature (77K) after vacuum heating and degassing the sample (100°C), and then using the BET method. The adsorption isotherm can be measured using a gas adsorption amount measuring device. For example, BELSORP-max (manufactured by Microtrac-Bell Co., Ltd.) may be used as the gas adsorption amount measuring device. The mass of the sample may be the mass of the sample after roughening treatment. If the change in the mass of the sample before and after roughening treatment is negligibly small, the mass of the sample before roughening treatment may be used as the mass of the sample.

[0016] The geometric surface area used to calculate surface roughness is a value obtained from the dimensions of the object being measured. For example, if the object being measured is a rectangular parallelepiped with length X, width Y, and height Z, the geometric surface area S can be calculated as S = 2XY + 2YZ + 2ZX. The geometric surface area measurement targets the surface of part or all of the anti-mold material. The object of measurement for geometric surface area may be the antifungal material after roughening treatment or the antifungal material before roughening treatment.

[0017] The arithmetic mean roughness (Ra) of the roughened surface of the antifungal material is not particularly limited. For example, the Ra of the roughened surface of the antifungal member may be 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more. For example, the Ra of the roughened surface of the antifungal member may be 100 μm or less, 10 μm or less, 5 μm or less, or 1 μm or less.

[0018] The ten-point mean roughness (Rz) of the roughened surface of the antifungal material is not particularly limited. For example, the Rz of the roughened surface of the antifungal member may be 0.2 μm or more, 1 μm or more, or 2 μm or more. For example, the Rz of the roughened surface of the antifungal member may be 500 μm or less, 200 μm or less, 100 μm or less, or 50 μm or less.

[0019] The average length (RSm) of the roughness curve elements of the roughened surface of the antifungal material is not particularly limited. For example, the RSm of the roughened surface of the antifungal member may be 10 μm or more, 50 μm or more, or 80 μm or more. For example, the RSm of the roughened surface of the antifungal member may be 500 μm or less, 200 μm or less, 100 μm or less, or 50 μm or less.

[0020] While the roughness index of the roughened surface of the antifungal material is an index that reflects the state of the three-dimensional structure on the nanometer order, RSm, Ra, and Rz of the roughened surface of the antifungal material are considered to be indices that reflect the state of the three-dimensional structure on the micrometer order.

[0021] In this disclosure, an antifungal member in which RSm, Ra, or Rz of at least a portion of the roughened surface are within the above-described range falls under the category of "an antifungal member in which RSm, Ra, or Rz of the roughened surface are within the above-described range." From the viewpoint of effectively exhibiting the antifungal properties of the antifungal material, the RSm, Ra, or Rz values ​​in 50% or more, 80% or more, or 90% or more of the roughened surface may be within the ranges described above.

[0022] In this disclosure, the RSm, Ra, and Rz values ​​of the roughened surface of the antifungal member are values ​​measured in accordance with JIS B 0601:2001 (corresponding international standard: ISO 4287).

[0023] The three-dimensional structure of the roughened surface of the antifungal member is not particularly limited as long as the roughened surface satisfies the conditions of the roughness index. For example, the roughened surface of the antifungal member may have a porous structure (hereinafter sometimes referred to as the "first microstructure") as described later, or it may have an uneven structure layer (hereinafter sometimes referred to as the "second microstructure") with an average thickness of 10 nm to 5000 nm, or it may have both the first microstructure and the second microstructure.

[0024] The presence of a porous or uneven structure layer on the roughened surface of an antifungal material can be confirmed by observing the roughened surface and a cross-section perpendicular to the roughened surface of the antifungal material using an electron microscope or laser microscope.

[0025] In this disclosure, "porous structure" refers to a structure having multiple pores. More specifically, "porous structure" refers to a structure in which pores exist in the observation area when a cross-section obtained by cutting an antifungal member horizontally to the roughened surface of the antifungal member is observed. In this disclosure, "hole" means an open vent (a hole connected to the outside air). The diameter of the hole is the value measured at the entrance of the hole.

[0026] The roughened surface of the antifungal member may have a plating layer with a porous surface structure. Examples of materials for the plating layer include zinc, nickel, and chromium. A plating layer with a porous surface structure can be formed by known methods. For example, a plating layer with a porous surface structure can be formed by the method described in the examples.

[0027] At least some of the pores in the porous structure of the antifungal member may have a shape in which the diameter of the opening is smaller than the maximum inner diameter of the inside of the pore (hereinafter also referred to as the ink bottle shape). In this disclosure, the "diameter of the opening" of a pore is the value measured at the entrance of the pore. If the roughened surface of the antifungal material has ink bottle-shaped pores, mold or viruses can be effectively attached to the roughened surface, and the antifungal performance is effectively exhibited.

[0028] The roughened surface of the antifungal component may have an uneven structure layer with an average thickness of 10 nm to 5000 nm.

[0029] The average thickness of the uneven structure layer may be 20 nm or more and less than 4000 nm, 30 nm to 2000 nm, 50 nm to 800 nm, 100 nm to 700 nm, 150 nm to 600 nm, more than 200 nm and 600 nm or less, or 350 nm to 600 nm.

[0030] From the viewpoint of effectively exhibiting antifungal properties, the average thickness of the uneven structure layer is preferably 100 nm or more, more preferably 200 nm or more, and even more preferably 250 nm or more.

[0031] The average thickness of the uneven structure layer is calculated from the cross-sectional profile obtained by scanning electron microscopy (SEM). Specifically, using a scanning electron microscope (SEM), SEM images are taken of 10 randomly selected points on the roughened surface of the antifungal material. Then, the average thickness over a length of 1 μm is measured for any two spots in each image, and the same measurement is performed for the other 9 points. The average of these 20 measurements is then taken as the average thickness of the second microstructure.

[0032] Examples of uneven structural layers include dendritic layers, reticular layers (sometimes called spongy layers), and pincushion layers.

[0033] The dendritic layer refers to a layer on the surface in which trunks made of a material derived from a roughened antifungal material stand in a dense cluster. The trunks may have branches that branch off from them, and the branches may have lateral branches that branch off from them. A mesh-like layer refers to a layer having a mesh-like or spongy shape, consisting of a substance derived from an antifungal material that has undergone a roughening treatment. A pincushion-like layer refers to a layer with sharp, irregularly shaped bumps and ridges, consisting of material derived from a roughened, antifungal material.

[0034] Substances derived from the roughened antifungal material include substances consisting of elements contained in the antifungal material and compounds containing elements contained in the antifungal material. Compounds containing elements contained in the antifungal material include oxides and hydroxides containing metal elements contained in the antifungal material. From the viewpoint of durability in environments where it comes into contact with liquids, oxides and hydroxides containing metal elements preferably contain aluminum.

[0035] The three-dimensional structure formed on the roughened surface of the antifungal member may be one type or a combination of two or more types selected from the specific forms described above.

[0036] The roughened surface condition of the antifungal material may be selected according to the properties, size, etc., of the mold or virus to which the antifungal performance is to be exerted.

[0037] The roughened surface of the antifungal component is obtained by roughening the surface of the substrate that will become the antifungal component. The method for roughening the surface of the substrate is not particularly limited. For example, if the substrate contains metal, a method using a laser as disclosed in Japanese Patent No. 4020957; a method of immersing the surface of the metal material in an aqueous solution of an inorganic base such as NaOH or an inorganic acid such as HCl or HNO3; a method of treating the surface of the metal material by anodic oxidation as disclosed in Japanese Patent No. 4541153; or a substitution crystallization method (hereinafter referred to as "roughening treatment method") which involves etching with an aqueous solution of an acid-based etchant (preferably an inorganic acid, ferric ions, or cupric ions) and optionally manganese ions, aluminum chloride hexahydrate, sodium chloride, etc., as disclosed in International Publication No. 2015-8847. Methods of roughening include: 1) a method of immersing the surface of a metal material in one or more aqueous solutions selected from hydrated hydrazine, ammonia, and water-soluble amine compounds, as disclosed in International Publication No. 2009 / 31632 (hereinafter sometimes referred to as "roughening method 2"); 3) a method of chemically roughening the surface of a metal material by contacting it with an oxidizing acidic aqueous solution containing a predetermined metal cation, as disclosed in International Publication No. 2020 / 158820 (hereinafter sometimes referred to as "roughening method 3"); 4) a hot water treatment method, as disclosed in Japanese Patent Publication No. 2008-162115, Japanese Patent Publication No. 2019-018547, etc.; and 5) a roughening treatment such as blasting.

[0038] From the viewpoint of achieving a surface roughness index of 4.0 or higher for a substrate containing metal, the roughening treatment methods 1 to 3 described later can be suitably used. Furthermore, treatments combining two or more of these roughening treatment methods (for example, a roughening treatment method combining roughening treatment method 1 and roughening treatment method 3) can also be suitably used.

[0039] [Roughening treatment method 1] One example of roughening treatment method 1 is a method in which the following steps (1) to (4) are carried out in this order.

[0040] (1) Pretreatment process In step (1), a pretreatment is performed to remove a film composed of an oxide film, hydroxide, etc. present on the surface of the substrate. As the pretreatment, mechanical polishing or chemical polishing treatment is usually performed. When there is significant contamination such as machine oil on the surface of the substrate, treatment with an alkaline aqueous solution such as an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution, or degreasing may be performed.

[0041] (2) Treatment step with a zinc ion-containing alkaline aqueous solution In step (2), the pretreated substrate is immersed in a zinc ion-containing alkaline aqueous solution containing an alkali hydroxide (MOH or M(OH)2) and zinc ions (Zn 2+ ) in a mass ratio ((MOH or M(OH)2) / Zn 2+ ) of 1 to 100 to form a zinc-containing film on the surface. Here, M in the above MOH and M(OH)2 is an alkali metal or an alkaline earth metal.

[0042] (3) Treatment step with an acid-based etching agent In step (3), after the execution of step (2), the substrate is treated with an acid-based etching agent containing at least one of ferrous ions and cupric ions and an acid. By performing step (3), the zinc-containing film on the surface of the substrate is eluted, and for example, a porous structure having at least one of Ra of 4 μm to 6 μm, Rz of 20 μm to 35 μm, and RS of 90 μm to 120 μm m can be formed.

[0043] (4) Post-treatment step In step (4), after the execution of step (3), the substrate is washed. The method for washing the substrate is not particularly limited, and usually consists of a water washing and drying operation. The method for washing the substrate may include an ultrasonic washing operation for removing smut.

[0044] [Roughening treatment method 2] In roughening treatment method 2, the substrate is pretreated with hydrochloric acid, sodium hydroxide, nitric acid, etc., then immersed in a weakly basic amine aqueous solution such as hydrated hydrazine, and subsequently washed with water and dried at, for example, 70°C or below. The immersion temperature and immersion time may be adjusted as appropriate according to the desired roughness index, desired average pore diameter, etc.

[0045] By the above method, for example, a porous structure of several hundred nanometers and a mesh-like structure with an average thickness of several tens of nanometers, which is further applied on top of the porous structure, can be formed on the surface of the substrate.

[0046] [Roughening treatment method 3] One example of roughening treatment method 3 is a method in which the substrate is brought into contact with a specific oxidizing acidic aqueous solution. The specific oxidizing acidic aqueous solution has a standard electrode potential of E at 25°C. 0 It contains a metal cation with a value greater than -0.2 and less than or equal to 0.8, preferably greater than 0 and less than or equal to 0.5. The above oxidizing acidic aqueous solution is E 0 It is preferable that the product does not contain metal cations with a value of -0.2 or lower.

[0047] Standard electrode potential E at 25°C 0 As for metal cations whose value is greater than -0.2 and less than or equal to 0.8, Pb 2+ Sn 2+ Ag + Hg 2+ Cu 2+ These are some examples. Among these, from the perspective of the rarity of the metal and the safety and toxicity of the corresponding metal salt, Cu 2+ It is preferable.

[0048] Cu 2+ Examples of compounds that generate this include inorganic compounds such as copper hydroxide, cupric oxide, cupric chloride, cupric bromide, copper sulfate, copper nitrate, and copper gluconate.

[0049] Examples of oxidizing acidic aqueous solutions include nitric acid, mixed acids, and percarboxylic acid aqueous solutions (e.g., peracetic acid, performic acid, etc.). Mixed acids can be obtained by mixing nitric acid with hydrochloric acid, hydrofluoric acid, or sulfuric acid. When nitric acid is used as the oxidizing acidic aqueous solution and cupric oxide is used as the metal cation generating compound, the concentration of nitric acid in the aqueous solution is, for example, 10% to 40% by mass, preferably 15% to 38% by mass, and more preferably 20% to 35% by mass. The concentration of copper ions in the aqueous solution is, for example, 1% to 15% by mass, preferably 2% to 12% by mass, and more preferably 2% to 8% by mass.

[0050] The temperature at which the substrate is brought into contact with the oxidizing acidic aqueous solution is not particularly limited, but in order to control the exothermic reaction and complete the roughening process at an economical speed, it is, for example, room temperature to 60°C, preferably 30°C to 50°C. The processing time at this time is, for example, in the range of 1 to 15 minutes, preferably 2 to 10 minutes.

[0051] By the above method, for example, a dendritic layer with an average thickness of several nanometers to several hundred nanometers can be formed on the surface of the substrate.

[0052] The material of the antifungal component is not particularly limited and can be selected according to its intended use. For example, the material of the antifungal component may be metal, resin, ceramic, carbon, etc., and may also be a combination of two or more different materials. Specifically, examples of metals include aluminum, iron, copper, nickel, gold, silver, platinum, cobalt, zinc, lead, tin, zirconium, titanium, niobium, chromium, aluminum, magnesium, manganese, and alloys containing the above metals. For example, the antifungal component may contain a resin. Specific examples of resins include thermoplastic resins (including elastomers) such as polyolefin resins, polyvinyl chloride, polyvinylidene chloride, polystyrene resins, AS resins, ABS resins, polyester resins (e.g., polybutylene terephthalate), poly(meth)acrylic resins, polyvinyl alcohol, polycarbonate resins, polyamide resins, polyimide resins, polyether resins, polyacetal resins, fluorine resins, polysulfone resins, polyphenylene sulfide resins, and polyketone resins, as well as thermosetting resins such as phenolic resins, melamine resins, urea resins, polyurethane resins, epoxy resins, and unsaturated polyester resins.

[0053] In one embodiment, the portion of the antifungal member corresponding to the roughened surface contains metal. The antifungal member, in which the portion corresponding to the roughened surface contains metal, may be obtained by roughening treatment of the metal-containing surface, or by other methods.

[0054] In one embodiment, the portion of the antifungal member corresponding to the roughened surface contains resin. The antifungal member, in which the portion corresponding to the roughened surface contains resin, may be obtained by a surface roughening treatment containing resin, or by other methods. For example, an antifungal member in which the portion corresponding to the roughened surface contains resin may be obtained by coating a roughened surface obtained by a surface roughening treatment containing metal with resin.

[0055] <Second Embodiment> A second embodiment of this disclosure is This product includes the antifungal component of the first embodiment described above.

[0056] The type of product in this embodiment is not particularly limited. From the viewpoint of effectively exhibiting the antifungal performance of the antifungal member, the product in this embodiment may be a product that has parts where condensation may occur. If the product of this embodiment has parts where condensation may occur, it is preferable that at least a portion of the parts where condensation may occur is made of an antifungal material. For example, 50% or more, 80% or more, or 90% or more of the area of ​​the parts of the product where condensation may occur may be made of an antifungal material.

[0057] Specific examples of products in this embodiment include air conditioning systems, humidifiers, ventilation systems, dust collectors, building materials, medical equipment, food and cooking utensils, piping, automobile parts, general merchandise, IT equipment, toys and play equipment, etc. Among these, it is preferable that the products in this embodiment be selected from the group consisting of air conditioning systems, humidifiers, ventilation systems, dust collectors, and building materials. The product of this embodiment may be made entirely of an antifungal material, or it may be made partially of an antifungal material. If the product of this embodiment consists of an antifungal member and a member other than the antifungal member, the material of the member other than the antifungal member is not particularly limited and may be metal, resin, ceramic, carbon, etc., or a combination of two or more different materials. [Examples]

[0058] The present disclosure will be described in more detail below with reference to examples. However, the present disclosure is not limited to these examples.

[0059] (Preparation of test specimen A1) An aluminum alloy sheet (thickness: 1.0 mm) of alloy number A5052 as specified in JIS H 4000:2014 was cut to prepare test specimens measuring 30 mm in length and 30 mm in width. These test specimens were degreased under the following conditions.

[0060] Composition: Meltex Co., Ltd. aluminum cleaner "NE-6" 5% by mass, water 95% by mass ·Temperature: 60℃ • Immersion time: 5 minutes

[0061] The degreased test specimen was subjected to the following Cu composition 2+Test specimen A1 was obtained by contacting it with an oxidizing acidic aqueous solution containing [substance name] under the following conditions and washing it with water.

[0062] ·Cu 2+ Composition of the oxidizing acidic aqueous solution containing: copper sulfate 5.03% by mass, nitric acid 30% by mass, water 64.97% by mass ·Temperature: 40℃ • Immersion time: 5 minutes

[0063] (Preparation of test specimen A2) After degreasing, the test specimens were immersed in an alkaline aqueous solution containing zinc ions with the following composition under the following conditions to form a zinc-containing coating on the surface. Next, the zinc-containing coating on the surface of the test specimen was eluted using an acid-based etching agent with the following composition under the following conditions, and then washed with water. Subsequently, test specimen A2 was obtained by contacting the test specimen with an aqueous solution containing copper sulfate of the following composition under the following conditions and washing it with water.

[0064] • Composition of zinc ion-containing alkaline aqueous solution: Sodium hydroxide 19% by mass, zinc oxide 3.2% by mass, water 77.8% by mass ·Temperature: 30℃ • Immersion time: 2 minutes

[0065] • Composition of the acid-based etching agent: Sulfuric acid 4.1% by mass, ferric chloride 3.9% by mass, cupric chloride 0.2% by mass, water 91.8% by mass ·Temperature: 30℃ • Immersion time: 250 seconds

[0066] • Composition of the aqueous solution containing copper sulfate: 30% by mass of nitric acid, 5.03% by mass of copper sulfate, 64.97% by mass of water ·Temperature: 40℃ • Immersion time: 5 minutes

[0067] (Preparation of test specimen A3) A nickel-plated undercoat layer approximately 3 μm to 4 μm thick was formed on the surface of the degreased test specimen. The undercoat nickel plating layer was formed using an aqueous solution containing nickel sulfate (280 g / L), nickel chloride (45 g / L), and boric acid (40 g / L) as the plating solution, at a solution temperature of 50°C, pH 4.3, and cathode current density of 3 A / dm². 2 It was carried out under the following conditions. Next, a nickel-plated layer having a porous structure with a thickness of approximately 1 μm to 5 μm was formed on the underlying nickel-plated layer. The porous nickel-plated layer was formed using a plating solution prepared by adding dodecyltrimethylammonium chloride (10 ml / L) as a substance that inhibits the growth of the plating layer to an aqueous solution containing nickel sulfate (280 g / L), nickel chloride (45 g / L), and boric acid (40 g / L), at a liquid temperature of 50°C, pH 4.3, and cathode current density of 3 A / dm². 2 It was carried out under the following conditions. Test specimen A3 was obtained by etching an aluminum plate with a nickel-plated layer having a porous structure by immersing it for 3 minutes in an aqueous solution (40°C) containing nitric acid (0.6% by mass) and phosphoric acid (7.5% by mass).

[0068] (Surface observation of the test specimen) The surface of the test specimens after roughening treatment was observed using a scanning electron microscope "Regulus8220" manufactured by Hitachi High-Technologies Corporation. On the roughened surface of specimen A1, no first microstructure was formed; only a dendritic second microstructure consisting of aluminum oxide was present. The roughened surface of specimen A2 had a first microstructure and a dendritic second microstructure made of aluminum oxide. The first microstructure had ink bottle-shaped pores with an opening diameter of approximately 10 μm and a maximum inner diameter of approximately 15 μm. A nickel-plated layer was formed on the roughened surface of specimen A3, having a first microstructure and a second microstructure resembling a pincushion. The first microstructure had ink bottle-shaped pores with an opening diameter of approximately 2 μm and a maximum inner diameter of approximately 2 μm.

[0069] (Roughness index) After roughening the test specimens, vacuum heating and degassing (100°C) was performed. Then, using BELSORP-max (manufactured by Microtrac-Bel Co., Ltd.), the adsorption isotherm was measured by krypton adsorption under liquid nitrogen temperature (77K), and the specific surface area (g / m²) was determined by the BET method. 2 The specific surface area (g / m²) was calculated. 2 The true surface area (m²) of the test specimen can be calculated from the mass (g) of the test specimen and the mass (g) of the test specimen. 2 The true surface area (m²) of the test specimen was calculated. 2 ) the geometric surface area (m²) of the test specimen 2 The surface roughness index was determined by dividing by ( ). The results are shown in Table 1. Furthermore, since the changes in geometric surface area and mass before and after the roughening treatment were very small, and their influence on the calculation of the roughness index was negligible, the geometric surface area and mass of the test specimen were used as the values ​​before the roughening treatment.

[0070] (Ra, Rz, and RSm) The arithmetic mean roughness (Ra), ten-point mean roughness (Rz), and average length (RS) of the roughness curve elements on the roughened surface of the specimen after roughening treatment. m The surface roughness was measured using the "Surfcom 1400D" surface roughness measuring device manufactured by Tokyo Seimitsu Co., Ltd. The results are shown in Table 1.

[0071] (Average thickness of the second microstructure) The average thickness of the second microstructure on the roughened surface of the specimen after roughening treatment was calculated from the cross-sectional profile obtained by scanning electron microscopy (SEM). The results are shown in Table 1.

[0072] (Antifungal test) To investigate the antifungal activity on the roughened surface of the test specimens, an antifungal test was conducted in accordance with JIS Z 2911:2023. The following five strains of fungi were used in the test. (1) Aspergillus niger NBRC 105649 (2)Penicillium citrinum NBRC 6352 (3) Rhizopus oryzae NBRC 31005 (4) Cladosporium sphaerospermum NBRC 6348 (5)Chaetomium globosum NBRC 6347

[0073] Chaetomium globosum was cultured for 21 days at 30±2°C after inoculating frozen strains onto potato dextrose agar (PDA) plates (Shimadzu Diagnostics) lined with filter paper. Other fungi were cultured for 7 days at 26±2°C after inoculating frozen strains onto PDA plates. Colonies that grew during culture were suspended in an aqueous solution of sodium dioctyl sulfosuccinate (0.005% aerosol OT solution, Fujifilm Wako Pure Chemical Industries), and the mycelium was removed by filtering with sterile cotton wool. The concentration was adjusted so that the number of spores per 1 mL was 10⁴ to 10⁶ to obtain a spore suspension. Equal volumes of the spore suspensions obtained from five different strains were mixed to obtain a mixed spore suspension.

[0074] To clean the roughened surface of the test specimen, each surface was irradiated with light for 20 seconds using a pulsed xenon lamp. The test specimen was placed in a petri dish, and a mixed spore suspension (0.08 mL) was dropped onto the test specimen and spread over the entire surface to inoculate it with mold spores. After inoculation, the test specimens were air-dried for approximately 12 minutes until the mixed spore suspension was completely dry. Then, the lids of the petri dishes were closed, and the specimens were left standing at 26±2°C for a predetermined period (1 week, 2 weeks, 3 weeks, or 4 weeks) under conditions where the relative humidity was 95% RH or higher. The number of tests for each specimen was n=3. The growth state of mycelium on the surface of the test specimens after a predetermined period of time was examined visually and evaluated according to the following criteria. As a control, the same antifungal test was conducted using specimens that had not undergone roughening treatment after degreasing. The results are shown in Table 1.

[0075] (judgment criteria) 0: No mycelial growth was observed in the inoculated area of ​​the test specimen. 1: The area of ​​mycelial growth observed in the inoculated portion of the test specimen shall not exceed 1 / 3 of the total area. 2: The area of ​​mycelial growth observed in the inoculated portion of the test specimen exceeds 1 / 3 of the total area.

[0076] [Table 1]

[0077] As shown in Table 1, test specimens A1, A2, and A3, which had a surface roughness index of 4.0 or higher, showed suppressed mycelial growth compared to the control specimen with a surface roughness index of 1.0. Furthermore, despite the Ra, Rz, and RSm values ​​of test specimen A1 being nearly identical to those of the control specimen, a significant difference in the state of mycelial growth was observed. This result suggests that it is the nanometer-order three-dimensional structure, rather than the micrometer-order three-dimensional structure, formed on the roughened surface of the antifungal material that contributes to the expression of antifungal performance.

Claims

1. True surface area (m²) measured by krypton adsorption method ２ ) is the geometric surface area (m ２ An antifungal member having a surface whose roughness index, obtained by dividing by ), is 4.0 or higher.

2. The antifungal member according to claim 1 for suppressing the growth of mold on the aforementioned surface.

3. The antifungal member according to claim 1, for use in an environment where condensation may occur on the aforementioned surface.

4. The antifungal member according to claim 1, wherein the portion corresponding to the aforementioned surface includes metal.

5. The antifungal member according to claim 1, wherein the portion corresponding to the aforementioned surface includes resin.

6. A product comprising the antifungal member described in claim 1, selected from the group consisting of air conditioning devices, humidifiers, ventilation devices, dust collectors, and building components.

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