JP2806582B2 - Activated carbon fiber sheet and filter - Google Patents

Description

The present invention relates to an activated carbon fiber sheet comprising activated carbon fibers and organic synthetic fibers having a fiber diameter of 1 μm or less.
The present invention relates to a flame-retardant, high-performance filter that has both the performance of collecting toxic gas and suspended fine particles.

[Related Art] In recent years, toxic gases such as odors and organic solvents and suspended fine particles such as dust have been increasingly discussed as pollution problems.

Adsorbents, especially activated carbon, are used as a means of preventing toxic gases, and activated carbon fibers are being rapidly developed because of the extremely fast gas adsorption rate.

However, regarding the removal of fine particles, a filter for removing fine particles may be used separately from the activated carbon filter, or a filter obtained by combining the activated carbon filter and the fine particle removal filter may be used. These require complicated production steps, and improvements are desired.

When the activated carbon fiber is formed into a sheet, a binder is necessary because the activated carbon fiber has no self-adhesiveness. As a binder for activated carbon fibers, various solution-type or emulsion-type liquid binders and fibrous binders are generally used.

The use of a liquid hinder is not preferable because it blocks the pores of the activated carbon fiber and lowers the adsorption capacity. In addition, there is no effect on removing fine particles. The use of fibrous hinders
In order to prevent the activated carbon fibers from falling off and obtain a sheet having sufficient strength, a large amount of fibrous binder is required, and the content of the activated carbon fibers in the sheet is reduced. In addition, the fibrous shape and the binder also have a large fiber diameter, and the collection of fine particles cannot be effectively removed.

[Problems to be Solved by the Invention] Several methods have been disclosed as means for solving the above-mentioned problems.

Japanese Patent Application Laid-Open No. Sho 62-155914 discloses a filter paper using activated carbon fibers, ultrafine glass fibers, and cellulose fibers. Activated carbon fiber has high adsorptivity, and ultra-fine glass fiber has high collection performance, but in order to form a sheet because both have no self-adhesiveness, it is necessary to add a binder in addition to the above components, The amount of activated carbon fibers is undesirably reduced. Cellulose fibers such as linter pulp and hemp pulp are used as the binder, but these fibers are flammable and it is inevitable that the sheet is flammable. In addition, the ultra-fine glass fibers are inevitably dropped off during use, and dust from the sheet itself is remarkable due to vibration, processing, and the like.

Japanese Patent Application Laid-Open No. 60-129112 discloses a nonwoven filter material using activated carbon and activated carbon fiber alone or as a mixture, a submicron glass fiber doctor (ultrafine glass fiber), and a fibrillated binder fiber. ing. JP 60
Japanese Patent Application Publication No. 94700 discloses a mixture of activated carbon and activated carbon fibers, alone or in combination, and a mixture of fibrillated acrylic fibers. The former is not preferable because ultrafine glass fibers are used. In addition, the fibrillated binder fiber is obtained by applying a shear force to fibers such as polyester, polyolefin, and acrylic polymer, and the fibrillated acrylic fiber is obtained by shearing the acrylic polymer fiber in the same manner. However, the filter medium using these organic fibers has a disadvantage that the pressure loss is higher than that of the ultrafine glass fiber because the fibers are flexible. It is flammable and cannot be used in applications where flame retardancy is required.

As described above, it is difficult to maintain the sheet strength and achieve both the performance of adsorbing toxic gases and the efficiency of collecting fine particles. At the same time, it is difficult to impart flame retardancy.

The present invention is to solve the above conventional problems,
Using an organic carbon fiber having a fiber diameter of 1 μm or less as a binder for activated carbon fibers, maintaining a high adsorptive capacity, collecting suspended fine particles at a high rate, and using a fire-retardant activated carbon fiber sheet and a filter comprising the sheet. The purpose is to provide.

[Means for Solving the Problems] The present inventors have conducted intensive research to solve the above problems. As a result, the filter obtained by using the activated carbon fiber and the organic synthetic fiber having a fiber diameter of 1 μm or less as a binder can obtain a high trapping rate without impairing the adsorption ability of the activated carbon fiber, The present invention has been completed.

That is, the present invention contains microfibrillated organic synthetic fibers having a fiber diameter of 1 μm or less obtained from activated carbon fibers and a rigid linear synthetic polymer, wherein the organic synthetic fibers are 5 to 50%, and the activated carbon fibers are 95 to 95%. It is an activated carbon fiber sheet containing 50%.

Further, it is a filter obtained by processing the activated carbon fiber sheet.

The activated carbon fiber sheet can be used as a filter.

 Hereinafter, the present invention will be described in detail.

The activated carbon fibers used in the present invention can be selected according to the purpose such as specific surface area and adsorptive capacity, but may be any as long as they are dispersed in water. If it is difficult to disperse, a viscous agent or a dispersant may be appropriately added and stirred. The average fiber length is 0.05 mm to 15 mm, preferably 0.5 mm to 10 mm. If it is shorter than 0.05 mm, the seeds become dense and the air permeability of the sheet decreases, and if it is longer than 15 mm, dispersion in water becomes poor.

In the present invention, organic synthetic fibers having a fiber diameter of 1 μm or less are used because of their excellent ability as a binder and excellent collection efficiency. As organic synthetic fibers, conventionally used flexible ones are not preferable because the pressure loss of the filter is high, which is not preferable. Therefore, the organic synthetic fibers are preferably as rigid as possible. Fiber is effective. The rigid linear polymer is a polymer having a chain length of 50 angstroms or more that maintains linearity in a solution, and examples thereof include poly (P-phenyleneterephthalamide), poly (P-benzamide), and poly (P-benzamide). -Phenylenebenzobisthiazole), poly (P-phenylenebenzobisoxazole), poly (amide hydrazide), polyhydrazide, poly (P-phenylene terephthalamide-3,4-diphenyl ether terphthalamide) and the like.

As an example of a method for obtaining a fiber having a fiber diameter of 1 μm or less, Japanese Patent Laid-Open Publication No.
Microfibrillated ones using the method disclosed in Japanese Patent Publication No. 0801 are mentioned. This method differs from the treatment by a refiner or the like used in a general papermaking process, in which a fiber or a pulp-like material is microfibrillated using a homogenizing device. That is, dispersed in water, rigid chain a slurry of fiber obtained from the polymer is passed through an orifice having a 200 kgf / cm ² or more of the pressure difference before and after a fast, shearing the slurry particles by immediately decelerating When a force is applied, the fibers become microfibrils that are longitudinally divided in the direction of the fiber axis. This is obtained by repeating this step. Specific examples include microfibrillated fibers (MFC-400, manufactured by Daicel Chemical Industries, Ltd.) of poly (P-phenylene terephthalamide).

The organic synthetic fiber used in the present invention has a fine fiber diameter of 1 μm or less, which cannot be obtained by a method of rubbing or shearing a commonly used fiber. It is large, has good entanglement with activated carbon fibers, and does not require any other binder such as pulp. Further, since the strength of the wet paper web formed on the wire of the paper machine is strong, the transfer to the next step is easy, and the paper can be efficiently manufactured with ordinary paper making equipment.

The amount of the organic synthetic fiber having a fiber diameter of 1 μm or less is 5% to 50%, preferably 10% to 40% based on the sheet weight. If the amount of the organic synthetic fiber having a fiber diameter of 1 μm or less is less than 5%, the strength of the sheet is low, and the collection efficiency is poor. If the amount is more than 50%, the collection efficiency increases, but the pressure loss increases, which is not preferable. .

It is also effective to mix whiskers of the above-mentioned rigid linear polymer in order to further increase the bulkiness of the sheet. Further, flame retardant fibrids may be further mixed.

If necessary, the activated carbon fiber sheet of the present invention may be subjected to a water-repellent treatment by spraying, applying, impregnating and drying a water-repellent agent. Also, mix the sizing agent into the slurry,
You may make paper.

If necessary, the activated carbon fiber sheet of the present invention can be mixed with other natural fibers, synthetic fibers, and inorganic fibers to make paper. It is also possible to mix inorganic filler and make paper. Furthermore, it is possible to contain a natural / chemical deodorant and a natural / synthetic fragrance. However, the content of these substances should not be in the range that impairs the performance of the sheet of the present invention.

The activated carbon fiber sheet of the present invention can adhere a backing material if necessary. The backing material preferably has good air permeability. As the bonding method, a commercially available adhesive may be used, or if the backing material is heat-fusible, heat bonding may be performed.

The activated carbon fiber sheet of the present invention can be easily cut by a cutter, a slitter, or the like, and can be incorporated in a unit or the like and used as a filter. Also, pleat weave processing,
Creates a single-sided or double-sided corrugated cardboard without damage even if subjected to corrugated processing, laminated so that the ridge line direction of the corrugated shape is parallel or perpendicular, or wound into a cylindrical shape to form a honeycomb structure, used as a filter It is also effective to do so.

[Activity] The activated carbon fiber sheet of the present invention can reduce the pores of the activated carbon fiber by using an organic carbon fiber having a diameter of 1 μm or less, which has a function as a binder and a function to collect fine particles, in the activated carbon fiber. It does not block and effectively acts as a filter that has a large amount of adsorption of foul odors and solvents, and has a high collection efficiency of fine particles.

[Examples] Hereinafter, the present invention will be described specifically with reference to Examples.
The present invention is not limited to this embodiment.

All parts and percentages described in the examples are by weight.

(Examples 1 to 3) Activated carbon fiber (specific surface area 1500 m ² / g, benzene adsorption capacity 53
0 mg / g, manufactured by Nippon Kainol Co., Ltd.) in water, adjusted to a concentration of 0.3%, dispersed with an SV type reciprocating reversing stirrer (Agiter, manufactured by Shimazaki Seisakusho), and then flame-retardant microfibrillated fibers (MF
C-400, manufactured by Daicel Chemical Co., Ltd.) while stirring with an agitator. At this time, the mixing ratio of activated carbon fiber and MFC-400 was adjusted to 90/10 (Example 1), 80/20 (Example 2), 60/40.
(Example 3) Three levels were prepared. Then, water was added to the slurry to dilute it to 0.1%, and a sheet having a dry weight of 80 g / m ² was cut into a square-shaped hand making device (wire mesh 80 mesh-wire mesh size 25 cm × 25 cm).
After the paper making in m), pressing and drying were performed to obtain an activated carbon fiber sheet.

(Comparative Examples 1 to 3) Ultrafine glass fibers (manufactured by john manville, CODE
106, fiber diameter of 0.54 to 0.68 μm) and fibrillated acrylic fibers were added and mixed. The mixing ratio of activated carbon fiber / ultrafine glass fiber / fibrillated acrylic fiber was 3 of 80/10/10 (Comparative Example 1), 65/25/10 (Comparative Example 2), and 10/50/40 (Comparative Example 3). Level adjusted. An activated carbon fiber sheet was obtained in the same manner as in Examples 1 to 3. Activated carbon fibers did not fall off.

Comparative Example 4 An activated carbon fiber sheet was obtained in the same manner as in Comparative Examples 1 to 3, except that the fibrillated acrylic fiber was replaced with linter pulp and hemp pulp. The mixing ratio of activated carbon fiber / ultrafine glass fiber / linter pulp / hemp pulp was prepared at 45/15/20/10.

Table 1 shows the measurement results of the physical properties of Examples 1 to 3 and Comparative Examples 1 to 4. The items are thickness, tensile strength, benzene adsorption capacity, pressure loss and collection efficiency. The benzene adsorption capacity was measured according to JIS-K1417. Pressure loss and collection efficiency are JI
It was measured at a wind speed of 5.3 cm / sec according to the format 1 of S-B9908. The collection efficiency was measured using a DOP aerosol (dioctyl phthalate, particle size 0.3 μm). Further, the flammability and whether or not the post-burning sheet form was maintained were represented by ○. Table 1 shows the results.

[Effect of the Invention] The activated carbon fiber sheet of the present invention comprises activated carbon fibers and organic synthetic fibers having a fiber diameter of 1 µm or less. Since the organic synthetic fiber having a fiber diameter of 1 μm or less has not only a function as a binder but also a function to efficiently collect fine particles, the activated carbon fiber sheet of the present invention maintains strength, has high adsorptivity,
In addition, the filter has a high trapping efficiency and is flame-retardant.

Claims (2)

(57) [Claims] 1. A microfibrillated organic synthetic fiber having a fiber diameter of 1 μm or less obtained from activated carbon fiber and a rigid linear synthetic polymer, wherein the organic synthetic fiber is 5 to 50% and the activated carbon fiber is 95 to 50%. % Activated carbon fiber sheet. 2. A filter obtained by processing the activated carbon fiber sheet according to claim 1.