JPH02251292A - Sterilizing material for cooling tower - Google Patents

Abstract

PURPOSE:To obtain the title sterilizing material showing stable sterilizing effect in spite of no elution of a sterilizing agent by sterilizing the water of an aqueous treatment apparatus generating an aerosol such as a cooling tower by the contact with the exposed part of a polymer surface by dispersing an inorg. carrier containing a sterilizing agent in a water-resistant polymer and molding the obtained dispersion. CONSTITUTION:An inorg. carrier containing a sterilizing agent is dispersed in a water-resistant polymer and the obtained dispersion is molded to prepare a sterilizing material for a cooling tower. From the aspect of the strong sterilizing power against bacteria of the genus Legionella and the safety to a human body, a silver ion, a copper ion or a compound thereof is proper as the sterilizing agent. As the inorg. carrier, crystalline aluminosilicate or activated carbon is pref. because it is prous and has a large specific surface area and can support a large amount of the sterilizing agent. As the water-resistant polymer, polypropylene or polyamide is designated. Further, it is proper to contain 20-90 pts.wt. of the above-mentioned sterilizing agent-containing inorg. carrier in 100 pts.wt. of the water-resistant polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sterilizing material in which an inorganic carrier containing a sterilizing agent is dispersed in a water-resistant polymer and molded.

[Conventional technology]

Conventionally, methods using ultraviolet lamps (JP-A No. 62-201689, etc.), chlorine thread chemicals,
Method using quaternary ammonium compounds (JP-A-60-5
No. 8905, JP-A-51-16703, etc.), but the bactericidal power against highly resistant microorganisms present in the generated Erysol was not sufficient. Issue] Microalgae, protozoa, heterotrophic bacteria, Legionella bacteria, etc. breed in large numbers in water from water treatment equipment that generates cooling tower ring aerosols. These microorganisms pose a risk of causing various infectious diseases through opportunistic infections in people with decreased physical strength.

In particular, bacteria of the genus Legionella was confirmed to exist in cooling towers, elevated water tanks, and hot water storage tanks, which are sources of aerosols, after a mass outbreak occurred at the American Veterans Association in 1976, and they are highly resistant to chemicals. Countermeasures have been suggested to control the microorganisms in Erysol that cause these opportunistic infections.

However, among the conventional sterilization methods, methods using ultraviolet irradiation require very large-scale equipment, are complicated to maintain, and are costly, so they have not been put into practical use.

Furthermore, methods using chlorine-based chemicals and quaternary ammonium compounds are insufficient in terms of safety for the human body and sustainability of the bactericidal effect.

The present invention has been made in view of the above points, and its purpose is to provide a method that can be applied to water in a simple manner, and that exhibits stable bactericidal activity over a long period of time in the applied state.
Furthermore, it is an object of the present invention to provide a sterilizing material for cooling towers that can be slightly leached into water.

[Means to solve 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 silver, copper,
Metal ions and their compounds such as zinc, mercury, lead, soot, bismuth, cadmium, or thallium; halogen compounds such as stabilized chlorine, hypochlorite, chloramine, and ethylene iodide; alcohols; phenols; and ethers. , guanidines, thiazoles, quaternary ammonium salts, thiocarbamay surfactants, and other organic compounds, preferably those with strong bactericidal activity against Legionella bacteria (from the viewpoint of being safe for the human body). Silver, copper ions or compounds thereof are suitable.

In the present invention, the inorganic carrier supports the bactericidal drug by adsorption, binding, ion exchange, etc., and the bactericidal drug is dissolved in water.
It is used for the purpose of stably exhibiting sterilizing power without decomposition.

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), amorphous aluminosilicate (hereinafter referred to as AAS), and activated carbon are preferred because they have a large specific surface area and can support a large amount of bactericidal agents.

In the present invention, as the "zeolite", both natural zeolite and synthetic zeolite can be used.

Zeolites are generally aluminosilicates with a three-dimensional skeleton structure, and have the general formula XM*/no-Al10
3 Displayed as ・YSiOt ・ZHiO.

Here, M represents an ion exchangeable ion and is usually an ion of l or a divalent metal. 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 8-type zeolide, etc. can be mentioned. However, the ion exchange capacity of these exemplary zeolites is not limited to these: 8-type zeolide 7 aeq/g, X-type zeolide 6 aeq/g.
．． 4 meq/g, Y-type zeolide 5 meq/g.

T-type zeolide 3.4+seq/g, sodalite 1
1, 5seq/g, mordenite 2.6meq/g
, to Anal Cyme 5meq, Clinoptilolite 2.6
meq/g, 5 aeq/g for chabasite, and 3.8 meQ/g for erionite, and both have sufficient capacity for ion exchange with silver ions and copper ions.

In the present invention, it can be used as a bactericidal aluminosilicate in which some or all of the ion-exchangeable ions in the amorphous aluminosilicate are replaced with the above-mentioned metal ions having bactericidal activity. AA used as raw material here
S (amorphous aluminosilicate) is not particularly limited, and conventionally known ones can be used as they are.

AAS generally has the composition formula XM! 0.81ids'ys
iog .zHtO, where M is generally an alkali metal element (eg, sodium, potassium, etc.), and x, y, and 2 indicate the molar proportions of metal oxide, silica, and water of crystallization, respectively. AAS is an amorphous substance that does not show a diffraction pattern even in X-ray diffraction analysis, unlike crystalline aluminosilicate called zeolite.
It is thought that the structure is such that several tens of minute zeolide crystals are produced in the synthesis process, and an amorphous substance consisting of a complex combination of 510m, AItoz, LO, etc. is attached to the surface of the crystals. AAS is generally produced by reacting an alkali metal solution at a predetermined concentration at a low temperature of 60° C. or lower, and washing with water before crystallization proceeds. As for the manufacturing method, for example, Japanese Patent Publication No. 52-58099, Japanese Patent Publication No. 55-16241
There is a method described in No. 8.

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. Moreover, it is preferable that copper is contained in an amount of 0.1 to 15%.

The antibacterial AAS can be produced, for example, by the following methods (1) and (2).

(1) Contacting an amorphous aluminosilicate with an M, O (M is an alkali metal) content of preferably 10% or less and a bactericidal metal ion allows for ion exchange in the amorphous aluminosilicate. Germicidal AAS can be produced by exchanging ions with biocidal metal ions.

(2) Preferably the pH of the amorphous aluminosilicate slurry is 6 or less! 11, and then bringing the amorphous fluminosilicate in the slurry into contact with bactericidal metal ions,
bactericidal AAS by exchanging ion-exchangeable ions in amorphous aluminosilicate with bactericidal metal ions.
can be manufactured.

In method (1), amorphous aluminosilicate (AAs)
), the Mho content is preferably 10% or less. AAS obtained by conventional methods contains more than 10% hO. Therefore, A obtained by the above method
For example, AS is suspended in water, and then an aqueous acid solution is added dropwise to the resulting slurry while stirring to neutralize the alkali metals and/or alkaline earth metals in AAS, thereby reducing the H2O content to 10% or less. can be adjusted to It is preferable to use a dilute acid aqueous solution having a concentration of Q, IN or less as the acid aqueous solution, and to carry out the dropwise addition at a rate of 100 mm or less, although this will vary depending on the stirring conditions and reaction scale.

Furthermore, neutralization is performed so that the 9H of the slurry is 3 to 6, preferably 4.
Acids that can be used for neutralization include inorganic acids such as nitric acid, sulfuric acid, perchloric acid, phosphoric acid, and hydrochloric acid, and organic acids such as formic acid, acetic acid, oxalic acid, and citric acid. Examples include acids.

M obtained by neutralization! AAS with an LO content of 10% or less can be filtered, washed with water, and used as a slurry in the method (1) as it is, or dried to have an LO content of 10%.
% or less of AAS, preferably in method (1), a slurry of AAS with an MzO content of 10% or less and an aqueous solution containing antibacterial metal ions are mixed to form silver ions,
A to a mixed aqueous solution containing bactericidal metal ions such as copper ions.
The AS is contacted to replace the ion-exchangeable ions in the AAS with the ions. Contacting is carried out at 5-70°C, preferably 40-60°C for 1-24 hours, preferably 10
It can be carried out batchwise or continuously (e.g. column method) for up to 24 hours.

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 nitrate #w4.
(n), perchlorate steel, copper acetate, potassium tetracyanocuprate, #I copper sulfate, etc. can be used.

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, if the antibacterial AAs contains silver ions, the content of silver ions in the mixed aqueous solution The silver ion concentration is 0.00
By setting it as 2M/J to 3.0M/j, antibacterial AAS with a silver ion content of 0.1 to 50% can be obtained as appropriate. In addition, when the antibacterial AAS contains copper ions, the copper ion concentration is Q, 005M71 ~ 5.0M/
By setting ffi, the copper ion content can be adjusted to 0.1 as appropriate.
-15% antibacterial AAS 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, the AAS is thoroughly washed with water and then dried. Drying is carried out at 105°C to 115°C under normal pressure or under reduced pressure (1
~30 Torr) is preferable.

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 hO content in AAS is 10% or less. It can be done. For adjusting the pH, the method exemplified in the method (1) above can be used similarly.

The pH-adjusted slurry can then be mixed with an antibacterial metal ion-containing solution to ion-exchange the AAS in the slurry. As the ion exchange method, a method similar to method (1) can be used as is.

In the present invention, activated carbon can be used as a bactericidal and inorganic carrier by treating the surface of the activated carbon with silver and copper compounds so that the compounds adhere thereto. 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 determined by the water-resistant polymer (from the viewpoint of dispersion, it is appropriate to set it to 0.05 to 10μ, preferably 0.1 to 3μ).The specific surface area of the inorganic carrier is 500μ.
rd /g or more, preferably 700 rd /g or more is suitable since it allows a large amount of bactericidal agent to be contained.

In the present invention, by dispersing an inorganic carrier containing a bactericidal agent in a water-resistant polymer and molding it, the bactericidal agent is eluted by contact sterilization of the bactericidal agent exposed on the polymer surface. (0.1 pp- or less) Furthermore, stable sterilizing power can be maintained for a long time.

Water-resistant polymers are composed of polymers of hydrophobic compounds, such as polypropylene, polyamide, polyethylene, polyurethane, melamine resin,
Examples include 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.

The content of the inorganic carrier containing the bactericidal agent in the water-resistant polymer is 20 to 100 parts by weight of the water-resistant polymer.
From the viewpoint of bactericidal activity, it is appropriate to use 90 parts by weight, preferably 40 to 60 parts by weight.

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. It is appropriate that the surface area of the molded product is 0.1 of/g or more, preferably lrd/8 or more, from the viewpoint that a large amount of the bactericidal agent contained therein comes out to the surface and effectively exerts its bactericidal power. Molding methods for molded articles having such a surface area include non-independent foam molding, honeycomb molding, cage molding, and the like.

Pigments as additives during molding of the sterilizing material for cooling towers of the present invention,
Fillers, antistatic agents, dispersants, surfactants, etc. can further be added.

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 in general buildings, hotels, apartment complexes, hospitals, etc. where aerosols are likely to be generated;
Can be used for general water-based treatment equipment such as elevated water tanks, hot water storage tanks, pools, humidifiers, cold air fans, toilet water tanks, water tanks for electric heaters with steam, metal processing oil, water-based paints, water-based emulsions, etc. , but not limited to these.

(Effects of the Invention) The sterilizing material for cooling towers of the present invention is effective in sterilizing water in aqueous treatment equipment where aerosols are generated, even though the sterilizing agent does not elute due to contact sterilization of the portion exposed to the polymer surface. It has a stable bactericidal effect.

〔Example〕

The present invention will be explained in more detail below using examples.

Reference Example 1 (Preparation of bactericidal aluminosilicate) Aluminosilicate is a commercially available A-type zeolide (NaxO・^It
(h' 1.95ift ・X LO: Average particle size 1
．． 5, us), commercially available Y-type zeolide (1, IN
atO^120.・4. I SiO
Three types of O.AltOz '2.36S (Ox.XHlOn average particle size 0.8 μm) were used.

N as a salt to provide each ion for ion exchange
H,NO,,AgN0z,Cu(NOs)x ・3H
! 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, water was added to 1 kg of powder that had been heat-dried at 110°C to make a slurry of 1.31, which was then stirred and degassed, and an appropriate amount of 0.5N nitric acid solution and water were added to adjust the pH.
was adjusted to 5 to 7 to make the entire slurry 1.81.
Next, for ion exchange, mix aqueous solution of a specified salt at a specified concentration & 3j! was added to bring the total volume to 4.81, and the slurry liquid was maintained at 40 to 60°C and stirred for 10 to 48 hours to reach an equilibrium state. After ion exchange, the aluminosilicate phase was filtered and washed with water at room temperature or hot water until the excess silver or copper ions in the aluminosilicate phase were removed.Next, the sample was heated and dried at 110°C.
Six types of samples and pulls were obtained. Obtained No, 1xNo,
Data for the No. 6 antimicrobial aluminosilicate samples are shown in Table 1.

Reference Example 2 (Preparation of bactericidal activated carbon) Dissolve 1180 g of #1 in 3 (l) of water, thoroughly mix IQKg of coconut shell powder activated carbon (particle size 29 μm),
After drying at 20℃, sodium chloride was dissolved in 50k of water, and the activated carbon was added to this solution and stirred well.
Filter the activated carbon on the filter cloth to about 100J of water! After washing with water and drying at 120°C, 9.7 kg of silver chloride-impregnated activated carbon was obtained. Silver chloride was contained at 0.67%.

Example (manufacture of germicidal material) A predetermined amount of germicidal aluminosilicate and germicidal activated carbon prepared in the reference example was added to 100 parts by weight of a water-resistant polymer, and the mixture was heated to φ in a twin-screw master chip extrusion molding machine.
2-1 A chip molded body having a length of 4n was manufactured.

A foam molded body (20 x 20 x 40 m) and a honeycomb molded body (φ25 x 40 am) with two square holes were also manufactured using ammonium carbonate as a foaming agent.

Table 2 shows the data of the 13 types of sterilizing materials No., A-M.

Test Example 1 (Bactericidal power test) A portion of the bactericidal materials of various shapes obtained in the Examples and the bactericidal aluminosilicate powder and bactericidal activated carbon obtained in the Reference Examples were
0Kg total water! In 2001, a column was filled and installed at the outlet of circulating water of a cooling tower of an air conditioner with a flow rate of 601/min. The bactericidal power of each was evaluated by measuring the number of general bacteria and the number of Legionella bacteria over the number of days that had passed. The results are shown in Table 3. The number of general bacteria and the number of Legionella bacteria before the experiment were 10'' and 10'' per ml, respectively.

Test Example 2 (Elution Test) The bactericidal material obtained in the example and the bactericidal aluminosilicate powder and bactericidal activated carbon obtained in the reference example were respectively placed in pure water 5.91 liters and stirred with a stirrer 50 rpm and 10.100 ml. and stirred for 500 hours.The amounts of silver and copper eluted from the supernatant solution were measured by atomic absorption spectrometry to evaluate the amount of bactericidal metals eluted.The results are shown in Table 4.

Claims (1)

[Claims] 1. A sterilizing material for cooling towers, characterized in that an inorganic carrier containing a sterilizing agent is dispersed in a water-resistant polymer and molded. 2. The sterilizing material for cooling towers according to claim 1, wherein the water-resistant polymer is polypropylene, polyamide, polyethylene, polyurethane, melamine resin, epoxy resin, or ABS resin. 3. The inorganic carrier containing the bactericidal agent is a water-resistant polymer 1
The sterilizing material for cooling towers according to claim 1, which is contained in an amount of 20 to 90 parts by weight based on 00 parts by weight.