JP7506889B2 - Antibacterial disinfectant carrier and method for producing same - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act January 21, 2020 Nihon Keizai Shimbun Published in the electronic version dated January 21, 2020

Application of Article 30, Paragraph 2 of the Patent Law January 22, 2020 Published in the morning edition of the Nikkei Shimbun on January 22, 2020, page 31 (Kita Kanto Economy)

Application of Article 30, Paragraph 2 of the Patent Act February 21, 2020 Published on page 9 of the Japan Agricultural News February 21, 2020

The present invention relates to an iodine-based antibacterial and disinfectant carrier having excellent antibacterial and antiviral properties, and a method for producing the same.

Iodine is necessary for the synthesis of thyroid hormones in the body and is an essential element for humans. On the other hand, iodine and iodine compounds have bactericidal and antiviral effects and are used as disinfectants. For example, alcohol solutions of iodine, glycerin solutions of iodine and potassium iodide, and complex compounds of iodine and polyvinylpyrrolidone are widely used as disinfectants.
In addition, iodic acid ( _HIO3 ), an oxoacid of iodine, is also used as a disinfectant because it has antibacterial and antiviral effects. For example, a germicidal cleaning agent composition containing iodine ions and iodic acid has been reported by adding hydrochloric acid and nitric acid to an aqueous solution of iodine chloride (Patent Document 1).

However, although iodine retains its bactericidal power in the form of elemental iodine or iodic acid, the bactericidal power is diminished when iodine diffuses in water, making it impossible to sustain its effectiveness over a long period of time, for example, in combating avian influenza viruses.
Therefore, the present applicants have reported an iodine-supporting material (Patent Document 2) in which iodine is supported on an adsorbent material such as activated carbon or fiber so that iodine is not released into the air or water, and the iodine is adjusted to be acidic so that iodate ions are not generated when iodine is supported. In addition, since activated carbon powder disperses in the air or water, the applicants have also reported a material (Patent Document 3) in which an iodate salt is formed on the surface layer of a material such as calcium silicate, providing an antibacterial and deodorizing mechanism.

Patent No. 3423971 Patent Application No. 2019-019044 Patent No. 6644325

However, while hydraulic inorganic materials containing calcium silicate and the like are materials that harden by reacting with water at room temperature and normal pressure, many of them are (weakly) alkaline and, after being sprayed outdoors, they are subject to deterioration due to acidic soil, ultraviolet rays, climate change, and other factors, resulting in insufficient durability. In addition, it is difficult to inexpensively produce acidic materials suitable for forming iodate salts at room temperature and normal pressure, so there has been a demand for the development of an iodine-based antibacterial disinfectant support that is inexpensive, easy to use, and has a long-lasting disinfecting effect.
Therefore, an object of the present invention is to provide an iodine-based antibacterial and disinfectant carrier having excellent antibacterial and antiviral activities, and a method for producing the same.

The inventors therefore carried out an investigation into the antibacterial activity of inorganic iodine compounds supported on various materials, and discovered that by supporting an inorganic iodine compound on a silica-based inorganic porous material derived from volcanic minerals and setting the pH, redox potential and bulk density of the support within certain ranges, the antibacterial activity is significantly improved and the material has good usability in a wide range of environments, leading to the completion of the present invention.

That is, the present invention provides the following [1] to [7].
[1] An antibacterial and disinfectant support in which an inorganic iodine compound is supported on a silica-based inorganic porous body derived from a volcanic mineral, the antibacterial and disinfectant support being characterized in that the antibacterial and disinfectant support has a pH of 2 to 5, an oxidation-reduction potential in an oxidized state, and a bulk density of 0.4 to 1.5.
[2] The antibacterial and disinfecting support according to [1], having an oxidation-reduction potential of +300 mV to +800 mV.
[3] The antibacterial and disinfectant support according to [1] or [2], wherein the silica-based inorganic porous material derived from a volcanic mineral has a pH of 4 to 7, an oxidation-reduction potential of +100 mV to +400 mV, and a bulk density of 0.4 to 1.5.
[4] The antibacterial and disinfectant support according to any one of [1] to [3], wherein the silica-based inorganic porous material derived from a volcanic mineral is selected from pumice, crushed pumice, a molded body of pumice or crushed pumice, and a packed body of pumice or crushed pumice.
[5] The antibacterial disinfectant support according to any one of [1] to [4], wherein the inorganic iodine compound is present in the support in the form of one or more ions selected from iodine, triiodide ion, iodate ion, and periodate ion.
[6] A method for producing an antibacterial and disinfectant support according to any one of [1] to [5], comprising supporting the inorganic iodine compound on the silica-based inorganic porous material derived from a volcanic mineral.
[7] The method for producing an antibacterial disinfectant support according to [6], wherein the inorganic iodine compound is one or more selected from iodic acid and iodate salts.

The antibacterial and disinfecting support of the present invention has an acidic pH and an oxidation-reduction potential in an oxidizing state, so that iodine and iodate are supported in sufficient quantities on a silica-based inorganic porous material derived from volcanic minerals in a state that allows for sustained release of iodine and iodate, and can be used not only for external environmental measures such as measures against avian influenza, but also as antibacterial and disinfecting building materials, etc.
Furthermore, when hard granules are used as a silica-based inorganic porous material derived from volcanic minerals, the hardness does not decrease even when the material has a high moisture content or is not dried, making it easy to store, transport, and spread mechanically, making it easy to use.

FIG. 1 shows antiviral activity. FIG. 13 shows the results of the bacterial inhibition zone (halo) of an antibacterial and disinfectant support using Hyuga soil. FIG. 13 is a diagram showing the results of the bacterial inhibition zone (halo) of an antibacterial and disinfectant support using Kanuma soil.

The antibacterial and disinfectant support of the present invention is an antibacterial and disinfectant support in which an inorganic iodine compound is supported on a silica-based inorganic porous body derived from a volcanic mineral, and is characterized in that the antibacterial and disinfectant support has a pH of 2 to 5, an oxidation-reduction potential in an oxidized state, and a bulk density of 0.4 to 1.5.

The pH of the antibacterial and disinfecting carrier of the present invention is preferably 2 to 5, more preferably 3 to 5, and even more preferably 4 to 5. By having a pH in this range, the carrier is highly safe and the supported inorganic iodine compound provides high antibacterial activity.

The pH of the silica-based inorganic porous material derived from volcanic minerals used in the antibacterial and disinfectant support of the present invention is 2 to 7. If the pH is less than 2, the metal parts of the manufacturing equipment for the antibacterial and disinfectant support may be easily deteriorated. On the other hand, if the pH exceeds 7, as in the case of calcium silicate described in Patent Document 3, the antibacterial activity of the supported inorganic iodine compound tends to decrease, which is not preferable.
The pH is preferably 2-7, more preferably 3-6, even more preferably 4-6, and still more preferably 4-5.
Here, the pH can be measured by mixing 10 g of the antibacterial disinfectant carrier or silica-based inorganic porous material with 50 ml of water at room temperature, shaking the mixture for 60 minutes, and using the resulting solution with a pH meter.

The oxidation-reduction potential of the antibacterial and disinfecting support of the present invention is in an oxidation state. When the oxidation-reduction potential is in an oxidation state, excellent antibacterial activity is obtained by the supported inorganic iodine compound. When the oxidation-reduction potential is on the reduction side, the antibacterial activity of the supported inorganic iodine compound tends to decrease.
From the viewpoint of obtaining excellent antibacterial activity, the oxidation-reduction potential is preferably +100 mV to +800 mV, more preferably +200 mV to +800 mV, and even more preferably +300 mV to +800 mV.

The redox potential of the silica-based inorganic porous material used must be on the oxidation side, preferably 0 mV to +400 mV, more preferably +100 mV to +400 mV, and even more preferably +200 mV to +400 mV, in order to bring the redox potential of the antibacterial and disinfecting support of the present invention into an oxidation state and obtain excellent antibacterial activity due to the inorganic iodine compound supported in the support, and is preferably 0 mV to +400 mV, more preferably +100 mV to +400 mV, and even more preferably +200 mV to +400 mV. If this redox potential is on the reduction side, the antibacterial activity of the supported inorganic iodine compound tends to decrease.
By supporting an inorganic iodine compound, the oxidation-reduction potential of the silica-based inorganic porous material increases by about +100 mV to +400 mV, preferably about +200 mV to +400 mV, and more preferably about +300 mV to +400 mV.
Here, the redox potential can be measured by mixing 10 g of the inorganic porous material or antibacterial and disinfecting carrier with 50 ml of water at room temperature, shaking for 60 minutes, and using the resulting solution with an redox potentiometer.

The bulk density of the silica-based inorganic porous material and the antibacterial and disinfecting support is preferably 0.4 to 1.5, more preferably 0.55 to 1.5, and even more preferably 0.6 to 1.5, from the standpoints of the antibacterial activity and strength of the support, reduction in equipment wear and tear required for transporting and mixing raw materials and products, reduction in energy costs required for production and transportation, prevention of dust generation from raw materials, and ease of operation when spraying manually or by power in granular form.
Here, the bulk density of the inorganic porous body and the antibacterial and disinfectant support refers to the loose bulk density when the porous body and the support are particles or powder, and refers to the bulk density of a plate-shaped test piece when the porous body and the support are molded bodies.
The loose bulk density of a powder or granular material can be measured by filling the porous body or support under its own weight into a 500 ml measuring cylinder without compressing, shaking or vibrating it, determining the volume, and then dividing the weight of the porous body or support used for filling by the volume.
The bulk density of the molded product can be measured by a method in accordance with JIS A 5430 8.5 bulk density test.

The inorganic porous body having the above-mentioned properties is a silica-based inorganic substance derived from a volcanic mineral, which is a porous body. Here, the calcium silicate used in Patent Document 3 is a silica-based inorganic substance, but is not a silica-based inorganic porous body of the present invention in terms of the above-mentioned pH and redox potential. Also, diatomaceous earth is not a silica-based inorganic porous body of the present invention in terms of its low bulk density of 0.1 to 0.2.
Specific examples of such silica-based inorganic porous bodies derived from volcanic minerals include those selected from pumice, crushed pumice, compacts of pumice or crushed pumice, and filled bodies of pumice or crushed pumice.

Pumice, also known as pumice, is a foamed, porous, mainly whitish pyroclastic rock.
Minerals contained in pumice include pumice, dacite, rhyolite, plagioclase, hypersthene, augite, amphibole, quartz, cristobalite, apatite, felsic rock, basalt, andesite, biotite, orthopyroxene, clinopyroxene, obsidian, magnetite, volcanic ash, quartz, olivine, volcanic glass, feldspar, scoria, tuff, pumice-bearing tuff, granite, andesite, quartz. Examples of such rocks include andesite, granodiorite, pumice volcanic gravel tuff, float, halloysite, allophane, imogolite, gypsite, volcanic breccia, tuff breccia, tuff agglomerate, scaly tuff, gabbro, diorite, porphyry, potassium feldspar, zeolite, axenite, fluorite, porphyrite, welded tuff, reticulite, acid clay, silica, sinter, and serpentine.
Therefore, all porous stones or rocks that contain these minerals as their main components and that satisfy the above-mentioned pH, oxidation-reduction potential, and bulk density are included in the pumice of the present invention.

Specific examples of such pumice include Kanuma soil, Imaichi soil, Miya soil, foxtail soil (foxtail sand), Hyuga soil, Ezo sand, Fuji sand, Akadama soil, Kiryu sand, Kirishima Oike mullet, Sakurajima Taisho mullet, mullet, kora, ash stone, gravel, quail, gravel, akahoya, kuroboku, and black niga.

These volcanic minerals have been deposited over a wide area of Japan's land area due to ashfall and mountain-building activity, so they can be easily and steadily obtained from strata close to the surface using simple mining equipment. Volcanic minerals derived from ashfall are also subject to wind-sorting during eruptions, making it easy to obtain minerals with uniform particle size. Furthermore, compared to mudstone, which is formed by the accumulation of organic matter on the bottom of the sea or lakes, volcanic minerals contain less organic matter, so they have the advantage that the antibacterial and disinfecting action of iodine-based compounds is less likely to be reduced by the organic matter that carries them.

The silica-based inorganic porous material includes pumice, crushed pumice, a molded body of pumice or crushed pumice, and a packed body of pumice or crushed pumice. The crushed pumice may be a crushed body of one type of pumice or a crushed body of two or more types of pumice. Furthermore, examples of the molded bodies of pumice or crushed pumice and the packed bodies of pumice or crushed pumice include shapes that can be used as building materials, such as plate-like bodies, wall materials, rectangular blocks, square pyramidal frustum-shaped gap stones, pellets, spheres, cylinders, upright columns, three-dimensional bodies formed by combining a plurality of plate-like bodies with fitting parts, broken stone shapes, sponge shapes, disk shapes, comb shapes, beads shapes, sheet bodies in which a porous body is fixed to one or both sides of a sheet-like material such as a glass sheet, a metal sheet, or a plastic film, packed bodies in which a porous body is filled in a bag made of a mesh of resin or metal, a panel body in which a box-like container having an opening is filled with the porous body and the porous body is exposed from the opening, a string-like body in which a porous body is fixed to a resin string, and large packed bodies in which the porous body is filled in a flexible container and stacked to form a wall surface or floor surface.
Pumice and crushed pumice are useful for use in external environments, such as in the prevention of disease in poultry farms as a measure against avian influenza, while molded articles such as plates and wall materials are useful for the prevention of disease in buildings.

The inorganic iodine compound supported on the silica-based inorganic porous material is not particularly limited as long as it is an inorganic iodine compound having antibacterial and antiviral properties.Specific inorganic iodine compounds include one or more selected from iodine, triiodide, iodic acid, periodic acid and their salts, and more preferably one or more selected from iodic acid and iodate salts.
In the antibacterial disinfecting carrier of the present invention, these inorganic iodine compounds are preferably present in the form of one or more selected from iodine, triiodide ion, iodate ion and periodate ion.

The amount of these inorganic iodine compounds supported on the antibacterial and disinfectant support of the present invention may be any amount that exhibits antibacterial and antiviral activity, and is not particularly limited. However, the amount is preferably 0.1% by mass or more, more preferably 0.2% by mass or more and 10% by mass or less, and even more preferably 0.2% by mass or more and 5% by mass or less, relative to the amount of the antibacterial and disinfectant support.

The antibacterial disinfectant support of the present invention can be produced by supporting an inorganic iodine compound on a silica-based inorganic porous material derived from a volcanic mineral. More specifically, the support can be produced by reacting the inorganic iodine compound dissolved or dispersed in a solvent with the silica-based inorganic porous material by mixing, coating, spraying or impregnation.
The inorganic iodine compound to be used may be one or more selected from iodine, triiodide, iodic acid, periodic acid, and salts thereof, and more preferably one or more selected from iodic acid and iodate salts.
The solvent is preferably water or a polar solvent, more preferably water. The operations of mixing, coating, spraying, or impregnation are preferably carried out at room temperature (usually 5 to 35° C.), and if drying is required, it is preferably carried out at room temperature to about 120° C.
The amount of the inorganic iodine compound used is determined taking into consideration the amount to be supported.

Among the antibacterial and disinfectant carriers of the present invention obtained as described above, there are those with high hardness and those with low hardness, depending on the characteristics of the silica-based inorganic porous material used as the raw material. For example, when Hyuga soil is used as the silica-based inorganic porous material, antibacterial and disinfectant carrier particles with high hardness are obtained. On the other hand, when Kanuma soil is used as the silica-based inorganic porous material, antibacterial and disinfectant carrier particles with low hardness are obtained. The antibacterial and disinfectant carriers obtained using Hyuga soil can be used as environmental disinfection materials as they are or by forming them into molded bodies or fillers. On the other hand, the antibacterial and disinfectant carriers obtained using Kanuma soil can be used as building materials, etc., by forming them into molded bodies or fillers. Here, the hardness of the silica-based inorganic porous material having high hardness is particularly preferably 20 to 70 N. The hardness can be determined as the load value when one particle is randomly selected and crushed by applying a compressive load.

The support of the present invention exhibits sustained antibacterial, antiviral and antifungal effects due to the action of the inorganic iodine compound carried thereon. Figure 1 shows an explanatory diagram of the action of the support of the present invention.
The antibacterial effect is a bacteriostatic or growth-inhibiting effect on various bacteria. Target bacteria include various pathogenic bacteria, including gram-negative bacteria and gram-positive bacteria.
The antiviral effect is an effect of reducing the toxicity of viruses (disinfecting effect), and examples of the viruses that can be targeted include influenza virus, AIDS virus, avian influenza virus, hog cholera virus, bovine coronavirus, bovine herpes virus, SARS virus, MERS virus, coronaviruses including the novel coronavirus, Newcastle disease virus, and foot-and-mouth disease.
The antifungal effect is a growth inhibition or bacteriostatic effect against various molds and filamentous fungi. According to the antifungal effect, the antifungal effect of the wall material can prevent allergies such as asthma caused by mold spores.
In the present invention, "disinfecting properties" include antiviral and antifungal properties.

The antibacterial and disinfecting carrier of the present invention can be used to prevent external environmental diseases such as avian influenza and hog cholera by scattering it around poultry farms, pig houses, etc., in place of the currently widely used slaked lime. In addition, by using the antibacterial and disinfecting carrier of the present invention as a wall material, buildings and the interior of buildings can be prevented from infection by various bacteria, viruses, and molds.

The present invention will now be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 (Supporting iodate on Hyuga soil)
Using 60 g of Hyuga soil with a particle size of 2 to 4 mm and 20 ml of an aqueous solution of an iodine compound (concentration 3%) in a glass container, the aqueous solution of an iodic acid compound was gradually dropped while stirring the Hyuga soil, so that the aqueous solution of the iodic acid compound was uniformly supported without remaining. The obtained antibacterial and disinfecting support maintained the granular shape before the support.

Example 2 (Supporting iodate on Kanuma soil)
In the same manner as in Example 1, 40 g of Kanuma soil with a particle size of 4 to 6 mm was mixed with 20 ml of an aqueous solution of an iodine compound (concentration 3%). The mixed Kanuma soil became a mixture of particles and a slightly viscous paste. The Kanuma soil carrying iodate could be separated into granular matter and powder by sieving.

The pH, redox potential, and bulk density of the silica-based inorganic porous bodies and the resulting supports used in Examples 1 and 2 are shown in Table 1.

Example 3 (Antibacterial effect of the carrier of the present invention)
(Method)
A bacterial inhibition zone (halo) test was carried out using the antibacterial disinfectant carrier described in Examples 1 and 2. The particles carrying the antibacterial disinfectant were placed on a standard agar medium inoculated with Escherichia coli, and incubated at 37°C for 17 hours to observe the inhibition zone.
(result)
The results are shown in Figures 2 and 3.
2 and 3 show that a support in which an inorganic iodine compound is supported on a silica-based inorganic porous material derived from a volcanic mineral, which has a pH of 2 to 5, an oxidation-reduction potential in an oxidized state, and a bulk density of 0.4 to 1.5, exhibits excellent antibacterial activity.

Example 4 (Antiviral effect of the carrier of the present invention)
(Method)
Antiviral tests were carried out using the antibacterial and disinfectant carriers described in Examples 1 and 2. The avian influenza virus A/swan/Shimane/499/83 (H5N3) strain was used as the virus. This virus was inoculated into the allantoic cavity of a 10-day-old developing chicken egg, cultured at 35°C for 2 days, and the allantoic fluid was collected to prepare a virus solution. The virus solution was prepared by calculating the 50% developing chicken egg infectivity titer (EID50) and adjusting the virus solution to about 107.5EID50/0.2mL with PBS (phosphate buffered saline). The eggs used were SPF fertilized eggs that were incubated and subjected to the test at 10 days of age.
400 mg of the antibacterial disinfectant carrier made of Hyuga soil prepared in Example 1 was weighed out and mixed with half the weight of the virus solution, and reacted at room temperature for 10 minutes. After the reaction, SCDLP (lecithin polysorbate 80 added soybean casein digest) medium was added, and the reaction was terminated by diluting 10 times. Then, the mixture was serially diluted 10 times with PBS, and 0.2 mL was inoculated into the allantoic cavity of three 10-day-old developing chicken eggs for each dilution step, and cultured at 35°C for 2 days. After the culture, the allantoic fluid was collected and reacted with a 0.5% chicken red blood cell suspension, and the presence or absence of virus proliferation was determined by red blood cell agglutination. The residual virus titer was calculated as EID50 by the Reed and Muench method.

(result)
The results are shown in Table 2. All of the antibacterial and disinfecting supports of Examples 1 and 2 exhibited strong antiviral activity against the avian influenza virus.

Example 5 (Hardness of particles used in the present invention)
(Method)
Using a Kiya-type digital hardness tester KHT40N manufactured by Fujiwara Seisakusho Co., Ltd., measurements were taken of particles of Hyuga soil and Kanuma soil in a dry state, dried at 60°C for 24 hours, and in a water-saturated state. For hardness measurements, one particle of each raw material was randomly selected, and a compressive load was applied to determine the load value when it was crushed. N=20 tests were performed. If the particles were soft and the load value of the hardness tester remained at the lower limit of the hardness tester and the particle size deformed to less than half its original thickness, it was deemed unmeasurable.
(result)
The average hardness (load bearing) of dry Hyuga soil was 40.5 N, with a maximum of 56.3 N and a minimum of 28.6 N. The average hardness (load bearing) of wet Hyuga soil was 38.1 N, with a maximum of 48.7 N and a minimum of 23.8 N.
For Kanuma soil, measurements were impossible in both dry and wet conditions.

Claims (8)

An antibacterial and disinfectant support in which an inorganic iodine compound is supported on a silica-based inorganic porous body derived from a volcanic mineral, the antibacterial and disinfectant support having a pH of 2 to 5, an oxidation-reduction potential in an oxidized state, and a bulk density of 0.4 to 1.5 , the silica-based inorganic porous body derived from a volcanic mineral being selected from pumice, crushed pumice, a molded body of pumice or crushed pumice, and a packed body of pumice or crushed pumice . The antibacterial and disinfecting carrier according to claim 1, which has an oxidation-reduction potential of +300 mV to +800 mV. The antibacterial and disinfecting carrier according to claim 1 or 2, wherein the silica-based inorganic porous material derived from a volcanic mineral has a pH of 4 to 7, an oxidation-reduction potential of +100 mV to +400 mV, and a bulk density of 0.4 to 1.5. The pumice may be pumice, dacite, rhyolite, plagioclase, hypersthene, augite, amphibole, quartz, cristobalite, apatite, felsic rock, basalt, andesite, biotite, orthopyroxene, clinopyroxene, obsidian, magnetite, volcanic glass, feldspar, scoria, tuff, pumice-bearing tuff, granite, andesite, dacite, granodiorite, pumice-bearing tuff, float, The antibacterial disinfecting support according to any one of claims 1 to 3, which contains a mineral selected from halloysite, allophane, imogolite, gypsite, volcanic breccia, tuff breccia, tuff agglomerate, slag tuff, gabbro, diorite, porphyry, potassium feldspar, zeolite, axenite, fluorite, porphyrite, welded tuff, reticulite, acid clay, silica stone, sinter and serpentine . The antibacterial and disinfectant support according to any one of claims 1 to 4, wherein the pumice is selected from Kanuma soil, Imaichi soil, Miya soil, foxtail soil (foxtail sand), Hyuga soil, Ezo sand, Fuji sand, Akadama soil, Kiryu sand, Kirishima Oike mullet, Sakurajima Taisho mullet, mullet, cola, ash stone, gravel, quail, gravel, Akahoya, Kuroboku and Kuroniga. The antibacterial and disinfecting support according to any one of claims 1 to 5 , wherein the inorganic iodine compound is present in the support in the form of one or more ions selected from iodine, triiodide ion, iodate ion and periodate ion. 7. A method for producing an antibacterial and disinfectant support according to any one of claims 1 to 6 , comprising supporting the inorganic iodine compound on a silica-based inorganic porous body derived from a volcanic mineral, wherein the silica-based inorganic porous body derived from a volcanic mineral is selected from pumice, crushed pumice, a molded body of pumice or crushed pumice, and a packed body of pumice or crushed pumice. 8. The method for producing an antibacterial disinfectant support according to claim 7 , wherein the inorganic iodine compound is one or more compounds selected from the group consisting of iodic acid and iodate salts.