JPH0512038B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a sterilizing material for bringing a sterilizing agent into contact with water to exhibit a sterilizing effect on water. [Prior Art] In the case of water-based sterilization, an appropriate amount of sterilizing agent is sprayed into water. However, while the bactericidal effect is immediate, the drug is quickly consumed for sterilization and loses its effectiveness in a short period of time. Therefore, there are products in which a bactericidal agent is contained in an inorganic carrier (for example, JP-A-61-72099, JP-A-63-
20090). These drugs have the advantage that their bactericidal effects are gradually exerted and their medicinal efficacy lasts for a long time. However, the above-mentioned inorganic carriers are easily destroyed and lost due to breakage and abrasion during use, and from a mechanical standpoint, the period during which a bactericidal agent can exert its bactericidal action is limited to a relatively short period. Ru. On the other hand, there are products with high mechanical strength that are molded by mixing bactericidal agents into resin (for example, JP-A No. 60-99389, JP-A No. 55-89336, JP-A No. 55-89336,
53−26061). However, these methods have a small exposed area of the bactericidal agent per unit volume. For this reason, when the exposed portion of the bactericidal agent is covered with adhesion of dirt and scale in the water during use, the amount of the agent that comes into contact with water is rapidly reduced. Therefore, in terms of bactericidal ability, the period during which the bactericidal agent can be effectively used is relatively short. [Problems to be Solved by the Invention] As described above, all of the conventional means for making a bactericidal drug exert a bactericidal action have a problem in that the effective period is short. The present invention was made to solve the problems (technical problems) of the prior art described above, and is mechanically strong and allows a large amount of the chemical to remain in contact with water for a long period of time. The object of the present invention is to provide a sterilizing material that can be used for a very long period of time. [Means for Solving the Problems] In order to achieve the above object, the sterilizing material for cooling towers of the present invention is obtained by dispersing an inorganic carrier containing a sterilizing agent in a water-resistant polymer and molding the same. The present invention will be explained below. In the present invention, examples of the bactericidal agent include:
Metal ions such as silver, copper, zinc, mercury, lead, tin, bismuth, cadmium or thallium and their compounds, stabilized chlorine, hypochlorite, chloramine,
Halogen compounds such as ethylene iodide, alcohols, phenols, ethers, guanidines,
Organic compounds such as thiazoles, quaternary ammonium salts, thiocarbamates, and surfactants can be mentioned, and silver and copper are preferred because they have strong bactericidal activity against Legionella bacteria and are safe for the human body. Ions or compounds thereof are suitable. In the present invention, the inorganic carrier adsorbs the bactericidal agent,
It is supported by bonding, ion exchange, etc., and is used for the purpose of allowing bactericidal agents to stably exhibit bactericidal activity without dissolving or decomposing in water. Examples of inorganic carriers include silica gel, alumina, crystalline aluminosilicate (synthetic or natural), amorphous aluminosilicate, activated clay, sepialite, clay materials, activated carbon, and various layered materials. Crystalline aluminosilicate (zeolite) and amorphous aluminosilicate (hereinafter referred to as AAS) because of their large specific surface area and ability to support a large amount of bactericidal agents.
and activated carbon are preferred. In the present invention, as the "zeolite", both natural zeolite and synthetic zeolite can be used. Zeolite is generally an aluminosilicate having a three-dimensional skeleton structure, and is represented by the general formula XM ₂ /nO.Al ₂ O _{3.YSiO 2.ZH 2} O. Here, M represents an ion exchangeable ion and is usually a monovalent or divalent metal ion. n is the valence of the (metal) ion. X and Y represent the respective metal oxide and silica coefficients, and Z represents the number of crystal water. Specific examples of zeolites include A-type zeolite, X-type zeolite,
Y-type zeolite, T-type zeolite, high silica zeolite, sodalite, mordenite, analcyme, clinoptilolite, chabasite,
Examples include erionite. However, it is not limited to these. The ion exchange capacity of these exemplary zeolites is
7meq/g, X-type zeolite 6.4meq/g, Y-
Type zeolite 5meq/g, T-type zeolite
3.4meq/g, sodalite 11.5meq/g, mordenite 2.6meq/g, analcyme 5meq/g, clinoptilolite 2.6meq/g, chabasite
5 meq/g, and erionite 3.8 meq/g, both of which have sufficient capacity for ion exchange with silver ions and copper ions. In the present invention, the amorphous aluminosilicate can be used as a bactericidal aluminosilicate in which part or all of the ion-exchangeable ions are replaced with the above-mentioned metal ions having bactericidal activity. AAS (amorphous aluminosilicate) used as a raw material here is not particularly limited, and conventionally known ones can be used as they are. AAS is generally represented by the compositional formula xM ₂ O.Al ₂ O ₃ .ySiO ₂ .zH ₂ O, where M is generally an alkali metal element (eg, sodium, potassium, etc.). Also x,
y and z indicate the molar ratio of metal oxide, silica, and crystal water, respectively. AAS is different from crystalline aluminosilicate called zeolite,
It is an amorphous material that does not show a diffraction pattern even in line diffraction analysis, and the synthesis process produces extremely fine zeolite crystals of several tens of angstroms, with SiO ₂ and
It is thought to have a structure in which an amorphous substance consisting of a complex combination of Al ₂ O ₃ , M ₂ O, etc. is attached. AAS is generally produced by reacting an alkali metal solution at a predetermined concentration at a low temperature of 60°C or less, and washing with water before crystallization progresses. Examples of manufacturing methods include those described in Japanese Patent Publication No. 52-58099 and Japanese Patent Application Laid-Open No. 55-162418. Among the bactericidal metals, it is appropriate to add silver in an amount of 0.1 to 50%, preferably 0.5 to 5%, from the viewpoint of exhibiting excellent bactericidal activity. Also, copper is 0.1 to 15
% is preferable. The above antibacterial AAS can be produced, for example, by the following methods (1) and (2). (1) Contacting an amorphous aluminosilicate with an M ₂ O (M is an alkali metal) content of preferably 10% or less with a bactericidal metal ion to perform ion exchange in the amorphous aluminosilicate bactericidal by exchanging ions with bactericidal metal ions
AAS can be manufactured. (2) Adjust the pH of the amorphous aluminosilicate slurry to preferably 6 or less, and then bring the amorphous aluminosilicate in the slurry into contact with bactericidal metal ions to perform ion exchange in the amorphous aluminosilicate. Germicidal AAS can be produced by exchanging biocidal metal ions for available ions. In the method (1), an amorphous aluminosilicate (AAS) having an M ₂ O content of preferably 10% or less is used. AAS obtained in the usual way
contains more than 10% _M2O . Therefore, the AAS obtained by the above method is suspended in water, for example,
Then, by neutralizing the alkali metal and/or alkaline earth metal in AAS by dropping an acid aqueous solution while stirring the obtained slurry.
The M ₂ O content can be adjusted to 10% or less.
It is preferable to use a dilute acid aqueous solution with a concentration of 0.1 N or less as the acid aqueous solution, and to perform the addition at a dropping rate of 100 ml/30 minutes or less, although this will vary depending on the stirring conditions and reaction scale. Furthermore, it is preferable to neutralize the slurry so that the pH thereof is in the range of 3 to 6, preferably 4 to 5. Acids that can be used for neutralization include inorganic acids such as nitric acid, sulfuric acid, perchloric acid, phosphoric acid, and hydrochloric acid, as well as formic acid, acetic acid,
Examples include organic acids such as oxalic acid and citric acid. AAS with M ₂ O content of 10% or less obtained by neutralization
can be filtered, washed with water, and used as a slurry in method (1), or dried.
AAS with an M ₂ O content of 10% or less may also be used. In method (1), preferably, a slurry of AAS with an M ₂ O content of 10% or less is mixed with an aqueous solution containing antibacterial metal ions, and AAS is added to the mixed aqueous solution containing bactericidal metal ions such as silver ions and copper ions. is contacted to replace the ion-exchangeable ions in AAS with the above ions. The contacting can be carried out at 5 to 70°C, preferably 40 to 60°C, for 1 to 24 hours, preferably 10 to 24 hours, in a batchwise or continuous manner (e.g. column method). Each ion in the mixed aqueous solution is usually supplied as a salt. The salts used include, for example, silver ions such as diammine silver nitrate and diammine silver sulfate, and copper ions such as copper nitrate, copper perchlorate, copper acetate, potassium tetracyanocuprate, and copper sulfate. The content of silver ions, etc. in AAS can be appropriately controlled by adjusting the concentration of each ion (salt) in the mixed aqueous solution. For example, antibacterial
When AAS contains silver ions, by setting the silver ion concentration in the mixed aqueous solution to 0.002M/~3.0M/, the silver ion content can be adjusted to 0.1~50M as appropriate.
% of antibacterial AAS can be obtained. In addition, when the antibacterial AAS contains copper ions, by setting the copper ion concentration to 0.005M/~5.0M/, the antibacterial AAS with a copper ion content of 0.1 to 15% can be used.
can be obtained. In addition to the mixed aqueous solution as described above, ion exchange can also be carried out by using an aqueous solution containing each ion individually and bringing each aqueous solution into contact with AAS sequentially. The concentration of each ion in each aqueous solution can be determined according to the concentration of each ion in the mixed aqueous solution. Further, in order to stabilize silver and copper ions during ion exchange, ammonium ions or amine ions such as methylamine can be added to the mixed solution and reacted. After ion exchange, AAS is thoroughly washed with water and then dried. Drying is preferably carried out at normal pressure at 105° C. to 115° C. or under reduced pressure (1 to 30 Torr). On the other hand, in method (2), the pH of the AAS slurry obtained by a conventional method is adjusted to 6 or less, preferably 3 to 6, more preferably 4 to 5, and the M ₂ O content in AAS is adjusted to 10. % or less. The PH can be adjusted using the same method as exemplified in the method (1) above. Next, the PH-adjusted slurry and an antibacterial metal ion-containing solution are mixed to remove AAS in the slurry.
can be ion exchanged. As for the ion exchange method, the same method as method (1) can be used as is. In the present invention, activated carbon can be used as a bactericidal inorganic carrier by treating the surface with silver and copper compounds to adhere the same compounds. The activated carbon used as a raw material here is not particularly limited, and any conventionally known activated carbon can be used as is. The above-mentioned inorganic carrier is prepared in powder form. The particle size is suitably 0.05 to 10 μm, preferably 0.1 to 3 μm, from the viewpoint of good dispersion in the water-resistant polymer. Further, it is appropriate that the specific surface area of the inorganic carrier is 500 m ² /g or more, preferably 700 m ² /g or more, since it can contain a large amount of bactericidal agent. In the present invention, dispersing an inorganic carrier containing a bactericidal agent in a water-resistant polymer and molding it,
Contact sterilization of the bactericidal agent exposed on the polymer surface makes it difficult for the bactericidal agent to elute (the elution amount is
(0.1ppm or less), making it possible to maintain more stable sterilizing power for a longer period of time. The water-resistant polymer is composed of a polymer of a hydrophobic compound, and examples thereof include polypropylene, polyamide, polyethylene, polyurethane, melamine resin, epoxy resin, and ABS resin. As a method for dispersing an inorganic carrier containing a bactericidal agent in a water-resistant polymer, many methods commonly used for dispersing inorganic powders such as pigments and fillers in polymers can be applied. From the viewpoint of bactericidal activity, it is appropriate that the content of the inorganic carrier containing the bactericidal agent in the water-resistant polymer be 20 to 90 parts by weight, preferably 40 to 60 parts by weight, per 100 parts by weight of the water-resistant polymer. . There are many conventional methods for molding a resin composition in which an inorganic carrier containing a sterilizing agent is dispersed in a water-resistant polymer as a sterilizing material for cooling towers, such as extrusion molding, injection molding, rolling molding, and blow molding. is applicable. The surface area of the molded product should be at least 0.1 m ² /g, preferably 1 m ² /g, from the viewpoint that a large amount of the bactericidal agent contained therein comes out to the surface and effectively exerts its sterilizing power.
It is appropriate to make it more than g. The surface area of the molded product
The reason for setting it to 0.1 m ² /g or more is as follows. It is known that many inorganic carriers have many irregularities. Even if this inorganic carrier is dispersed in a polymer, the surface area of many samples is 0.1 m ² /g, as is clear from Table 2 below.
That's all. This means that even if an inorganic carrier is dispersed in a polymer, many irregularities of the inorganic carrier are exposed on the surface of the molded product. On the other hand, when only the water-resistant polymer in the sample in Table 2 is molded into the same shape as the sample,
The surface areas of the molded products are all very small. For example, in the case of nylon in Experiment No. C, it is 0.00166 m ² /g. This means that the surface area of the molded article will not become as large as described above unless the unevenness of the inorganic carrier is exposed. Other methods of molding a molded article having such a surface area include a non-independent foam molding method, a honeycomb molding method, a cage molding method, and the like. Pigments, fillers, antistatic agents, dispersants, surfactants, etc. can be further added as additives during molding of the sterilizing material for cooling towers of the present invention. The sterilizing material for cooling towers of the present invention has excellent sterilizing properties against various microorganisms that cause opportunistic infections such as Legionella bacteria that breed in the water of aqueous treatment equipment that generates aerosols, and also has excellent algae-proofing properties. , cooling towers, elevated water tanks, hot water storage tanks, etc. in general buildings, hotels, apartment complexes, and hospitals where aerosols are likely to be generated, as well as swimming pools, humidifiers, cold air fans, toilet water tanks, water tanks for electric steam heaters, and metal processing. It can also be used in general water-based treatment equipment such as oil, water-based paints, water-based emulsions, etc.
It is not limited to these. [Effects of the Invention] As described above, in the present invention, it is possible to bring the bactericidal agent into contact with water by immersing it in water, and to exert a bactericidal effect. The inorganic carrier containing the drug is tightly held around its periphery by a water-resistant polymer, which has the advantage of being able to be mechanically held tightly. Furthermore, even if the inorganic carrier is supported by the polymer, the surface area of the inorganic carrier is
Because it is dispersed in the polymer in a wide area of 0.1 m ² /g or more, even if the surface of the sterilizing material is covered with dust or scale during use, it will maintain its sterilizing properties when in contact with water. It has the advantage of allowing a large amount of the drug to remain. That is, the fact that the molded product has a surface area of 0.1 m ² /g or more means that many of the irregularities of the inorganic carrier are exposed on the surface of the molded product, as described above. Therefore, even if dirt and scale adhere to the surface of the inorganic carrier over time and cover it, the insides of the many recesses remain in contact with water and are exposed to each of the many recesses. It has the feature that a large amount of bactericidal agent exerts a bactericidal effect. Therefore, due to the above two features, namely, the ability to mechanically retain the inorganic carrier containing the bactericidal agent and the ability to maintain the bactericidal effect regardless of the adhesion of dust or scale, the bactericidal material of the present invention has bactericidal properties. It is useful because it allows the bactericidal action of the drug to be effectively exerted over a very long period of time. [Example] The present invention will be explained in more detail below with reference to Examples. Reference Example 1 (Preparation of bactericidal aluminosilicate) Aluminosilicate is commercially available A-type zeolite (Na ₂ O・Al ₂ O ₃・1.9SiO ₂・XH ₂ O: average particle size
1.5μm), commercially available Y-type zeolite (1.1Na ₂ O・
Al ₂ O ₃・4.1SiO ₂・XH ₂ O: average particle size 0.7 μm) and amorphous aluminosilicate (1.04Na ₂ O・Al ₂ O ₃・2.36SiO ₂・
Three types of XH ₂ O (average particle size: 0.8 μm) were used.
NH ₄ NO ₃ , AgNO ₃ , Cu(NO ₃ ) 2.3H _{2 O} as salts to provide each ion for ion exchange.
type was used. Table 1 shows the type of zeolite used in preparing each sample and the type and concentration of salt contained in the mixed aqueous solution. Six types of bactericidal aluminosilicate samples No. 1 to No. 6 were obtained. For each sample, powder 1 was heated and dried at 110℃.
Kg was added with water to make a 1.3 slurry, then stirred and degassed, and an appropriate amount of 0.5N nitric acid solution and water were added to adjust the pH to 5 to 7, making the entire slurry 1.8. Next, for ion exchange, add a mixed aqueous solution 3 of a specified salt at a specified concentration to bring the total volume to 4.8
This slurry liquid is kept at 40~60℃ and heated to 10~48℃.
The mixture was stirred for a period of time to reach an equilibrium state. After the ion exchange was completed, the aluminosilicate phase was filtered and washed with room temperature water or hot water until excess silver or copper ions in the aluminosilicate phase disappeared. Next, the samples were heated and dried at 110°C to obtain six types of samples. Table 1 shows data regarding the antibacterial aluminosilicate samples No. 1 to No. 6 obtained. Reference Example 2 (Preparation of bactericidal activated carbon) Dissolve 80g of silver nitrate in 30ml of water, mix well with 10kg of coconut shell powder activated carbon (particle size: 9μm),
Dry at 120°C. Next, dissolve sodium chloride in 50% of water, add the above-mentioned activated carbon to this solution, stir well and filter, wash the activated carbon on the filter cloth with 100% of water, dry at 120°C, and dissolve silver chloride impregnated activated carbon with 9.7% of water.
Got Kg. It contained 0.67% silver chloride. Example (Manufacture of sterilizing material) Add a specified amount of sterilizing aluminosilicate and sterilizing activated carbon prepared in the reference example to 100 parts by weight of a water-resistant polymer, and while heating it, mold it to φ2 mm using a twin-screw master chip extrusion molding machine. A chip molded body with a length of 4 mm was manufactured. A foam molded body (20 x 20 x 40 mm) and a honeycomb molded body (φ25 x 40 mm) with holes of 2 mm square were also produced from the chip molded body using ammonium carbonate as a foaming agent. Table 2 shows the data of the 13 types of sterilizing materials No. A to M obtained. Test Example 1 (Bactericidal power test) 10 kg of the various shapes of the sterilizing material obtained in the example and a part of the sterilizing aluminosilicate powder and sterilizing activated carbon obtained in the reference example were mixed in a total water volume of 200 ml and a flow rate of 60/min. A column was filled and installed at the outlet of the circulating water of the cooling tower of the air conditioner. By measuring the number of general bacteria and the number of Legionella bacteria over the number of days that have passed,
The bactericidal activity of each was evaluated. The results are shown in Table-3.
The number of general bacteria and the number of Legionella bacteria before the experiment were 10 ⁸ cells/ml and 10 ⁵ cells/ml, respectively. Test Example 2 (Elution test) The bactericidal material obtained in the example, the bactericidal aluminosilicate powder and the bactericidal activated carbon obtained in the reference example were respectively placed in pure water 5.9, and stirred at 50 rpm with a stirrer for 10, 100 and 500 hours. Stirred. The amounts of silver and copper eluted from the supernatant solution were measured by atomic absorption spectrometry to evaluate the amount of sterilizing metals eluted. The results are shown in Table 4.

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Claims (1)

[Claims] 1. A bactericidal agent is contained in an inorganic carrier, and the inorganic carrier is incorporated into a water-resistant polymer so that the surface area of the molded product is
A sterilizing material for cooling towers characterized by being dispersed and molded to a state of 0.1 m ² /g or more. 2.Claim 1 wherein the water-resistant polymer is polypropylene, polyamide, polyethylene, polyurethane, melamine resin, epoxy resin or ABS resin.
Sterilizing material for cooling towers as described. 3. The sterilizing material for a cooling tower according to claim 1, wherein the inorganic carrier containing the sterilizing agent is contained in an amount of 20 to 90 parts by weight based on 100 parts by weight of the water-resistant polymer.