JPH10165809A - Antimicrobial adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent proliferation of bacteria even when bacteria deposit on an adsorbent by using an adsorbent essentially comprising an activated carbon fiber having a specified or larger specific surface area and a thermoplastic fiber, and incorporating silver and/or inorg. silver compds. into both of the activated carbon fiber and the thermoplastic fiber. SOLUTION: The activated carbon fiber and the thermoplastic fiber contain silver or inorg. silver compds. or both of silver and inorg. silver compds. As for silver, metal silver, silver ion, etc., can be used. As for inorg. silver compds., silver chloride, silver bromide, etc., can be used. The activated carbon fiber into which the silver component is to be incorporated is preferably produced from a pitch-based fiber as the source material by treating to make the fiber infusible and activated to form fine pores. The obtd. fiber has preferably >=500m<2> /g specific surface area, especially >=900m<2> /g. As for the thermoplastic fiber, a core-sheath composite fiber comprising polyester is used. Since the antimicrobial adsorbent obtd. by mixing the activated carbon fiber and the thermoplastic fiber contains the silver component in both fibers, proliferation of bacteria can be prevented by the sterilizing effect of the silver component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a gas phase deodorizing filter used in an air conditioner, an air purifier, a deodorizing machine, and the like.
The present invention relates to an antibacterial adsorbent suitable as an adsorbent for a liquid phase used in a 24-hour bath, a water purifier, and the like.

[0002]

2. Description of the Related Art In recent years, the problem of microbial contamination of the air has become socially apparent as seen in allergic asthma and the like caused by airtightness of buildings. As a deodorizing filter of an air conditioner or an air purifier, an activated carbon molded product is generally used. Air conditioners and air purifiers have a dust collector, which collects dust in the air and bacteria attached to the dust. However, 100% of these bacteria cannot be collected, and some dust and dust are not collected. Bacteria that have adhered to the dust often adhere to the deodorizing filter downstream of the dust collection part. If bacteria adhere to the deodorizing filter, they will be propagated as a nutrient source by dust and moisture adsorbed on activated carbon, causing new problems. For example, mold (fungi) spores adhere to the spores, and when spores multiply, form a large number of spores. The spores are scattered and become a new air pollution source or putrid odor.

In order to solve such a problem, Japanese Patent Laid-Open Publication No. Hei 7-163640 proposes an antibacterial / deodorizing filter containing activated carbon fibers impregnated with silver and / or an inorganic silver compound as a main component. Since the silver component is impregnated in the activated carbon fibers constituting the filter, even if bacteria adhere to the filter, the propagation of the silver component can be prevented to some extent by the bactericidal action of the silver component. However, it is difficult to form a deodorizing filter using only activated carbon fiber.
Contains a large amount of thermoplastic fiber as formed by mixing activated carbon fiber of the above with 30% by weight of thermoplastic fiber for the binder, and the thermoplastic fiber does not have antibacterial properties. There is a problem that if bacteria adhere to the soil, they will propagate without being sterilized.

[0004] Also, when an adsorbent mainly composed of activated carbon fiber impregnated with a silver component is used for 24 hours as an adsorbent for a liquid phase such as a bath or a water purifier, the same as when used for a gas phase. If bacteria adhere to the thermoplastic fibers for the binder, they proliferate without being sterilized, and there is a demand for an adsorbent with improved antibacterial properties.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and provides an antibacterial agent capable of preventing the growth of bacteria adhering to both the activated carbon fiber portion and the thermoplastic fiber portion constituting the adsorbent. An object of the present invention is to provide a hydrophobic adsorbent.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention relates to an adsorbent mainly composed of activated carbon fibers having a specific surface area of 500 m ² / g or more and thermoplastic fibers, wherein both the activated carbon fibers and the thermoplastic fibers are silver and / or
Or, an antibacterial adsorbent characterized by containing an inorganic silver compound.

Hereinafter, the present invention will be described in detail. The antibacterial deodorizing material of the present invention is formed by using activated carbon fiber and thermoplastic fiber as main components, and both activated carbon fiber and thermoplastic fiber are silver or inorganic silver compound, or silver and inorganic silver compound. It contains both.

The silver to be contained in both the activated carbon fiber and the thermoplastic fiber includes metallic silver, colloidal silver, silver ions and the like. As the inorganic silver compound, silver chloride,
Silver halides such as silver bromide and silver iodide, silver nitrate, silver sulfate,
Examples thereof include silver phosphate, silver sulfide, silver chlorate, silver silicate, and silver oxide. Among them, silver chloride, silver nitrate, and silver oxide are preferable.

As a method for incorporating silver or an inorganic silver compound (hereinafter, simply referred to as a silver component) into both fibers, a method of attaching after forming into a fibrous form, or adding to a raw material polymer before forming into a fibrous form. A method or the like can be adopted.

[0010] In order to impregnate both fibers, a silver component is dissolved or suspended in water or an organic solvent, the fiber is impregnated with the silver component, dried and, if necessary, further calcined. And drying and baking if necessary. In addition, for example, silver nitrate and sodium chloride are made into separate aqueous solutions, respectively, and one of them is impregnated with a fiber and then the other is impregnated. In the case of activated carbon fiber, silver chloride is formed on the inner surface of the pores of the fiber. Various water-soluble compounds can be separately applied to form a water-insoluble silver compound on the surface of the fiber.

When the silver component is impregnated on the activated carbon fiber, it may be at the stage of the precursor fiber, or after the both fibers are mixed and formed into a felt shape or a filter shape. In addition, when adding a silver component to the raw material polymer of thermoplastic fiber,
For example, as described in JP-A-6-272173, antibacterial zeolite particles carrying silver ions are added to a raw material polymer of thermoplastic fiber so that the fiber concentration becomes 1.5% by weight. A method of dispersing and melt-spinning can be adopted.

The amount of silver added to each fiber is preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight in terms of silver.
When the amount of silver component is small, the effect of suppressing the growth of bacteria on the adsorbent decreases, and when the amount of silver component is large, in the case of impregnation, the silver component is easily adhered to the surface and is easily separated. In other words, spinning becomes difficult when added to the raw material polymer.

Next, activated carbon fibers containing a silver component are:
Pitch-based, polyacrylonitrile-based, cellulose-based, phenolic-based, etc. fibers are used as raw materials to form micropores by infusing and activating in the usual way.
Those having a specific surface area of 500 m ² / g or more, particularly 900 m ² / g or more are preferred. If the specific surface area is less than 500 m ² / g, when the silver component is contained in a required amount by the impregnation method, the specific surface area and the pore volume are reduced, and the adsorption effect by micropores is not preferable. The specific surface area is determined from the adsorption of nitrogen gas by the theoretical equation of BET.

In particular, in a gas-phase deodorizing filter, the activated carbon fibers preferably have an equilibrium moisture content of 10% or more at a temperature of 25 ° C. and a relative humidity of 60%. In general, activated carbon fibers are hydrophobic and therefore have low hygroscopicity. However, those with an equilibrium moisture content of 10% or more at a temperature of 25 ° C and a relative humidity of 60% absorb the moisture in the air and liquid as appropriate, and The contained silver component gradually elutes out as active silver ions, exhibiting a strong growth inhibitory effect and an antibacterial effect on microorganisms and bacteria. Activated carbon fibers having an equilibrium moisture content of 10% or more at a temperature of 25 ° C. and a relative humidity of 60% can be obtained by, for example, oxidizing ordinary activated carbon fibers in steam.

There are two types of activated carbon, granular and fibrous. In the present invention, fibrous activated carbon fibers are used. The adsorbent using activated carbon fiber has a significantly higher adsorption speed for the substance to be adsorbed than the adsorbent using granular activated carbon, and can exhibit a sufficient adsorption effect even in a small amount. Weight and weight can be reduced. Activated carbon fiber also has an extremely large outer surface area, about 100 times that of the granular adsorbent, and it is considered that the silver component contained in the activated carbon fiber comes into direct contact with bacteria to exhibit antibacterial effects. Furthermore, since the activated carbon fiber can be formed into various shapes, it has a great advantage that a filter having a low pressure loss such as a honeycomb shape or a corrugated shape can be manufactured. In addition, activated carbon fiber can be made with a larger specific surface area than ordinary activated carbon, so it is possible to increase the content of silver components, and the antibacterial effect of silver components and the adsorption effect of pores are increased. A molded article such as a filtered filter can be obtained.

As the thermoplastic fiber constituting the antibacterial adsorbent of the present invention together with the activated carbon fiber, for example, a monocomponent fiber made of polyester, nylon, polyethylene, polypropylene, copolymerized polyester or the like, or a polyester in the core and a sheath in the sheath There is a core-sheath composite fiber using polyethylene, polypropylene, copolymerized polyester or the like.

The mixing ratio of the activated carbon fiber and the thermoplastic fiber is preferably in the range of 98: 2 to 40:60, particularly 95: 5 to 50:50 by weight. If the ratio of the activated carbon fiber is too large, the formability of the felt-like material is deteriorated.

The method of mixing activated carbon fiber and thermoplastic fiber is as follows.
For example, activated carbon fiber and thermoplastic fiber are put into a roller card machine at a predetermined ratio, and after mixing while putting the card,
It is possible to adopt a method in which the material is integrated by a needle punch into a felt-like material. Also, a method of obtaining a felt-like material by a wet method by a papermaking method while mixing activated carbon fibers and thermoplastic fibers may be used. Further, natural fibers such as hemp and cotton can be mixed with these.

As the antibacterial adsorbent of the present invention, activated carbon fiber and thermoplastic synthetic fiber are mixed in a dry or wet manner to form a felt, or the felt is heated to obtain a thermoplastic resin. Activated carbon fiber and thermoplastic synthetic fiber or a felt-like material obtained by fusing together thermoplastic synthetic fibers obtained by melting part or all of the synthetic fiber, and at least one surface of these felt-like materials A nonwoven fabric such as a synthetic fiber or a natural fiber, a woven fabric, a knitted fabric, or the like is laminated by needle punching or heat fusion. In addition, the above-mentioned felt-like material before fusion may be wound into a cylindrical or cylindrical shape and fused to form a cylindrical or cylindrical body. Further, it may be used after being formed into a honeycomb or corrugated shape. Good.

The activated carbon fibers constituting the adsorbent of the present invention are:
Activated carbon fiber containing silver component and activated carbon fiber not containing silver or a specific substance are used as adsorbents that contain silver component but have low antibacterial load and large load of adsorbent. It is preferable from the viewpoints of performance and cost to mix and mold activated carbon fibers containing a drug for removing the carbon dioxide.

When dust-removing performance is required in addition to antibacterial and deodorizing properties, it is preferable to use the adsorbent of the present invention in combination with a dust-removing filter. When the adsorbent of the present invention is used in combination with the dust filter,
In order to maintain antibacterial properties and adsorptivity, it is preferable to install a dust filter on the upstream side and the adsorbent of the present invention on the downstream side.

Although the performance of the antibacterial adsorbent of the present invention decreases with use, it can be reused. The method of regeneration is not particularly limited as long as the silver component does not fall off, but regeneration with hot air is preferred from the viewpoint of regeneration efficiency and cost.

The antibacterial adsorbent of the present invention is used as a gas phase deodorizing filter such as an air conditioner, an air purifier, a deodorizer, and a liquid phase adsorbent used in a 24-hour bath or a water purifier. It is used, but both activated carbon fibers and thermoplastic fibers that constitute the adsorbent contain a silver component. Therefore, even if bacteria adhere to the adsorbent, the bacteria are propagated by the bactericidal action of the silver component. It is possible to prevent.

[0024]

Next, the present invention will be described in detail with reference to examples.

Examples 1 to 5 and Comparative Examples 1 to 3 Pitch fibers melt-spun and made infusible using coal pitch as a raw material were steam-activated at an activation temperature of 850 ° C. for 30 minutes to obtain activated carbon fibers. This activated carbon fiber was steamed at a temperature of 9
Oxidation treatment is performed at 50 ° C, internal pressure 0.002kg / cm ² , oxygen concentration 0.5 volume% for 20 minutes, specific surface area 1010m ² / g, pore volume 0.45ml / g, average pore diameter 17mm , Fiber diameter 15μm, temperature 25
Activated carbon fiber with an equilibrium moisture content of 10% at 60 ° C and a relative humidity of 60% was prepared. Next, this was impregnated with silver nitrate aqueous solutions having different concentrations, impregnated with 0 to 5% by weight as metallic silver, washed with water and dried to obtain silver-impregnated activated carbon fibers (a) to (f).

Next, the concentration of antibacterial zeolite particles carrying silver ions in the fiber was 1.0% by weight based on the molten polymer.
Composite melt-spinning was performed using polyethylene terephthalate copolymerized with 40% by mole of isophthalic acid in the sheath and polyethylene terephthalate in the core, stretched, crimped, cut, and cut to 15d A core-sheath type antibacterial polyester cotton of 51 mm was prepared. Also, a core-sheath type polyester cotton of 15d × 51 mm was prepared in the same manner as described above except that no antibacterial zeolite particles carrying silver ions were added.

The obtained silver-impregnated activated carbon fibers and two kinds of polyester cottons were variously combined as shown in Table 1, and put into a roller card machine at a weight ratio of 70:30, and mixed while putting cards. After being woven and then integrated by needle punch, a polyester fiber and a silver-impregnated activated carbon fiber were heat-fused at a temperature of 90 ° C. to obtain a felt-like material.

[0028]

[Table 1]

This felt-like material was cut into a size of 20 mm × 20 mm, placed in a test tube, and subjected to a heat sterilization treatment at a temperature of 121 ° C. and a pressure of 15 atm for 15 minutes to obtain an adsorbent.

Next, S. aureus (Staphylococcus aureus) or E. coli (Escherichia coli) was diluted with a 1/20 tryptic soy medium in advance to obtain 8.5 × 10 ⁹ cells / ml and 5.2 × 10 ⁸ cells / ml. The adsorbent was inoculated with 100 μl of the bacterial solution adjusted to ml, and cultured at 37 ° C. for 24 hours. After culturing, a phosphate buffer solution containing 0.2% -Tween80 (a surfactant manufactured by Wako Pure Chemical Industries, Ltd.) was added to the test tube.
Bacteria adhering to the adsorbent were shaken off by shaking with a test tube mixer for 1 minute, inoculated on a normal agar plate, and the number of colonies formed on the agar medium was counted to determine the number of residual bacteria. Table 2 shows the obtained results.

[0031]

[Table 2]

As is clear from Table 2, antibacterial properties were observed in all of the adsorbents of Examples 1 to 5. Among them, activated carbon fibers having silver impregnated in an amount of 0.1% by weight or more were used. However, the bactericidal effect was particularly good. On the other hand, the adsorbent of Comparative Example 1 in which both the activated carbon fiber and the polyester fiber did not have silver impregnated did not exhibit antibacterial properties, but rather increased the number of residual bacteria. Antibacterial properties were observed in the adsorbent of Comparative Example 2 in which only activated carbon fiber was impregnated with silver, but the effect was obtained by using both activated carbon fiber and polyester fiber impregnated with silver. It was inferior to those of Examples 1 to 5.

[0033]

According to the antibacterial adsorbent of the present invention, both the activated carbon fiber and the thermoplastic fiber constituting the adsorbent contain a silver component. The germicidal action of the silver component can prevent its propagation, and the bacteria do not propagate on the adsorbent, so that it can be used for a long time without producing putrefactive odor.

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Claims (1)

[Claims] 1. An adsorbent mainly comprising activated carbon fibers having a specific surface area of 500 m ² / g or more and thermoplastic fibers, wherein both the activated carbon fibers and the thermoplastic fibers are silver and / or inorganic silver compounds. An antibacterial adsorbent characterized by containing.