JPH0712429B2 - Molded adsorbent - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrally formed molded adsorbent having a three-dimensional structure using activated carbon fibers.

[0002]

2. Description of the Related Art Activated carbon fibers (also called activated carbon fibers or fibrous activated carbon) have been used as adsorbents since around 1975. Activated carbon fiber has a larger surface area per unit weight than conventionally used granular activated carbon, has a smaller pore diameter and a sharper distribution than granular activated carbon, and has excellent adsorption characteristics. Therefore, it is attracting attention as a new adsorbent.

However, activated carbon fibers have the following problems: (1) It is difficult to increase the adsorption amount per unit volume because of its low bulk density.

(2) Activated carbon fibers are very weak because there are countless pores of Angstrom unit on the surface of fine fibers having a diameter of 2 to 30 microns. For example, if it is rubbed with a fingertip once or twice, it becomes powdery easily.

Therefore, there is a demand for a shaped adsorbent having a high bulk density, which uses activated carbon fibers having weak mechanical properties and a low bulk density.

The following are known as adsorbents for the gas phase and liquid phase using activated carbon fibers, but none of them have been able to achieve the above object.

(1) There is an adsorbent in which activated carbon fibers and heat-meltable synthetic resin fibers are mixed or spun, and then heated to fuse or bond them together (for example, JP-A-56).
-24151).

The obtained adsorbent is used for deodorizing and purifying air,
It is used for recovery of solvent from gas phase, concentration of solvent, liquid phase treatment (removal of chlorine, decolorization, deodorization, etc.), separation of single gas (molecular sieve), etc.

However, according to this method, it is difficult to produce an adsorbent having a high bulk density and a dense three-dimensional structure. Further, a loss occurs during the cutting process, and it is necessary to reprocess it into a predetermined shape, resulting in a high cost.

(2) Organic fibers such as acrylic fibers and phenolic resin fibers are needle-punched into a felt-like or non-woven fabric, or these fibers are formed into threads and then woven, followed by heat treatment or chemical treatment. There is an adsorbent that has been activated by.

The activated carbon fiber structure thus obtained has a very large number of micropores having a pore diameter of about 10 to 40 angstroms, and its specific surface area is 700 to
It is about 2500 m ² / g. Therefore, the strength of the structure is significantly reduced to about 1/10 of the original strength of the felt-like or woven form, and it is easy to collapse or break during use.

Even by this method, it is difficult to produce an adsorbent having a high bulk density and a dense three-dimensional structure.

(3) The carbon fiber is niddle punched into a felt shape or a non-woven fabric, or a filament shape, and then a woven fabric, which is then heat-treated or chemically treated to be activated carbonized to obtain an adsorbent.

Also in this case, since the strength of the obtained structure is low, there are practical problems similar to those in the above (2), and it is difficult to manufacture an adsorbent having a high bulk density and a dense three-dimensional structure. Is.

[0015]

[Means for Solving the Problems] Activated carbon fibers have excellent adsorption properties, but weak mechanical strength and low bulk density. The present inventor has conducted various studies to develop a molded adsorbent having a dense bulky structure having a large bulk density using activated carbon fibers having such properties, and as a result, activated carbon fibers that should exhibit an adsorption function and the fibers. Prepare a water-based slurry containing a heat-meltable synthetic resin (either fibrous or powder-like. The same applies hereinafter) to be used as a joining material for joining the two to each other, and have a large number of suction holes. When the hot-melt synthetic resin is melted by suction-molding with a mold, dehydration, and heating, a molded adsorbent that can substantially solve or significantly reduce the problems of the prior art is obtained. I found that

That is, the present invention provides a shaped adsorbent as follows: "Containing activated carbon fiber and thermofusible synthetic resin, the content of the thermofusible synthetic resin is 0 per 100 parts by weight of activated carbon fiber. .2 parts by weight or more and 40 parts by weight or less, and an integrally formed molded adsorbent having a three-dimensional structure having a papermaking structure in which activated carbon fibers are randomly bonded and held by a hot-melt synthetic resin. An adsorbent having a papermaking structure refers to an adsorbent having a dense structure in which fibers constituting the adsorbent are randomly arranged like thick Japanese paper.

The adsorbent having a three-dimensional structure means an adsorbent having a shape other than a thin adsorbent having a thickness of 3 mm or less, such as a sheet or a tape. Specifically, a columnar shape, a prismatic shape, an elliptic cylinder shape, a truncated cone shape, a truncated pyramid shape, a pellet shape, a rectangular parallelepiped shape, a cubic shape, or a shape having a hole in them (eg, the columnar body described above). A cylindrical adsorbent having openings through the upper and lower surfaces of the columnar body and having through holes with the central axis of the columnar body as the central axis.

The integrally formed adsorbent means an adsorbent formed by laminating a sheet-shaped or tape-shaped adsorbent with an adhesive or the like. More specifically, It is obtained by molding all or part of a three-dimensional structure adsorbent at once.

The shaped adsorbent refers to an adsorbent whose shape has been imparted by using a forming die when the adsorbent is manufactured.

In the present invention, the activated carbon fiber is not particularly limited and may be appropriately selected depending on the field of use of the adsorbent, but usually the fiber diameter is about 2 to 30 μm and the fiber length is about 0.5 to 10 mm. , Micropores with a diameter of about 8 to 20 angstroms, and a specific surface area of 500 to 2500 m
It is preferable to use one having a concentration of about ² / g. Further, the origin thereof is not limited, and any of rayon type, polyacrylonitrile type, phenol resin type, coal pitch type, petroleum pitch type and the like may be used.

As the hot-melt synthetic resin for bonding and integrating activated carbon fibers, those having a melting point of about 50 to 200 ° C. are preferable, and polyethylene, polypropylene, polyvinyl alcohol, polyacrylonitrile, polyester, etc. are exemplified. In particular, polyacrylonitrile is most suitable. As the heat-meltable synthetic resin, it is more preferable to use a thread-like (fibrous) resin because it does not clog the pores of the activated carbon. As the heat-meltable synthetic resin yarn, a yarn having a yarn diameter of about 5 to 100 μm and a length of about 0.5 to 10 mm is preferable. As the heat-meltable synthetic resin yarn, one having a structure in which the surface of a high-melting fiber yarn that does not melt or deteriorate at the heating temperature during the production of the molded adsorbent is coated with the heat-meltable synthetic resin may be used.

The blending amount of the heat-meltable synthetic resin with respect to 100 parts by weight of activated carbon fiber is about 0.2 to 40 parts by weight, preferably about 0.2 to 20 parts by weight. If the blending amount of the heat-meltable synthetic resin is too small, the strength of the molded adsorbent will be low, and if the blending amount is too large, the pores of the activated carbon fiber will be blocked and the porosity will be reduced. When the molded product requires a certain amount of strength, the activated carbon fiber content is large, and it is necessary to exert its characteristics, the blending amount of the heat-meltable synthetic resin is appropriately about 5 parts by weight.

The shaped adsorbent of the present invention is manufactured as follows.

First, a uniform aqueous slurry containing activated carbon fibers and a heat-meltable synthetic resin in a predetermined ratio is prepared.
The solid content concentration in the aqueous slurry is not particularly limited,
From the viewpoint of ease of handling and molding, 0.1
It is preferably about 2% by weight. When preparing the slurry, mechanical dispersion or stirring is performed according to a conventional method, if necessary. Further, a dispersant, a stabilizer, a viscosity modifier, a paper strength enhancer, a yield improver and the like may be added as long as the performance of the molded adsorbent is not impaired. The homogeneous aqueous slurry thus obtained is molded.

Molding is preferably carried out while preliminarily dehydrating under reduced pressure, such as suction molding. More specifically, for example, in the case of producing a cylindrical body, a mold having a cylindrical core having a large number of suction small holes on the surface of which both ends are sealed with blind flanges is immersed in the slurry. The fiber components are randomly accumulated and formed on the surface of the core body by sucking the slurry with a pump through a suction nozzle provided at one end of the flange. When the length of the cylindrical product is short, it is also possible to suction from the end face and randomly form the fiber component. In the case of a molded adsorbent having a three-dimensional structure without pores, it can be molded by suctioning using a molding die having at least one small pore for suctioning. Suction molding can also be performed by supplying the slurry to the mold and dehydrating it without burying the mold in the slurry.

The formed molded product in a wet state is dehydrated as desired, and then the molded product is heated at a temperature according to the heat-melting synthetic resin used to melt the synthetic resin to integrate the molded product. The molded adsorbent of the present invention is obtained by drying.
The heating temperature varies depending on the temperature at which the resin exhibits adhesiveness and the resin used, but is preferably about 40 to 60 ° C. higher than the softening point.

According to this manufacturing method, a molded adsorbent having a certain level of strength and which can be used as it is can be obtained. The molded adsorbent having high strength can be obtained even though the amount of the heat-meltable resin used is small, because the molded adsorbent obtained in the present invention has fibers randomly. That is,
In the vicinity of the suction surface, the fibers are randomly oriented substantially parallel to the suction surface, but when they are moved away from the suction surface, some of the fibers are randomly suction-collected on the suction surface at various angles. It is considered that the fibers sucked at this angle contribute to the shape retaining action. However, since the activated carbon fiber is still a weak substance by nature, the strength of the molded adsorbent obtained from only the activated carbon fiber and the heat-meltable synthetic resin is insufficient depending on the purpose of use. In this case, it may be necessary to use the molded adsorbent housed in the case. Therefore, in order to obtain a molded adsorbent having higher strength, it is desirable to use the non-thermofusible fiber as a reinforcing material.

As the non-thermofusible fiber as the reinforcing material,
It is not particularly limited as long as it does not melt or deteriorate at the heating temperature during the production of the molded adsorbent, but it is usually an inorganic fiber such as glass fiber or alumina fiber; polyamide fiber, high melting point polyethylene fiber, high melting point polypropylene fiber, high melting point Synthetic fibers such as polyacrylonitrile fibers, semi-synthetic fibers such as rayon, and pulp fibers are used. The yarn diameter of the non-thermofusible fiber is 2 to 1 from the viewpoint of the effect as a reinforcing material.
The length is preferably about 00 μm, and the length is preferably about 0.5 to 10 mm from the viewpoint of dispersibility in the aqueous slurry used in the production of the adsorbent and the effect as a reinforcing material. Non-heat-meltable fiber is activated carbon fiber 10
It is preferable to add about 5 to 80 parts by weight to 0 part by weight. If the blending amount is too large, the amount of the activated carbon fiber is relatively reduced, so that the performance as the adsorbent is deteriorated.

A third adsorbent material such as activated clay, ion-exchange fiber, molecular sieve, siliceous earth, zeolite, silver-impregnated activated carbon, granular activated carbon or powdered activated carbon may be further added.

When the wet-molded product of the present invention is used, the fluid containing the substance to be adsorbed is preferably caused to flow in the suction direction at the time of molding. This is because delamination is less likely to occur even when the amount of heat-meltable synthetic resin used is small.

[0031]

EFFECTS OF THE INVENTION The molded adsorbent having a three-dimensional structure of the present invention exhibits the following performance while using activated carbon fibers having low strength and low bulk density.

(1) Bulk density is usually 0.08 to 0.25 g
/ Cm ³ (in the embodiment, 0.222 g / cm ³ , 0.16
5 g / cm ³ ) of adsorbent is obtained. Depending on how the third fiber is used, it is possible to obtain an adsorbent having a bulk density of 0.40 g / cm ³ .

(2) Since it has a high bulk density and a dense structure,
The adsorption amount per unit volume can be increased, the device can be downsized, the adsorbed substance-containing fluid does not short-pass during use, and the flow rate of the adsorbed substance-containing fluid can be increased.

(3) Since it is integrally molded, it is easy to handle.

(4) Since the activated carbon fibers are densely accumulated and bonded and held by the heat-melting synthetic resin, the fibers are randomly present and have an arbitrary angle with respect to the suction surface to have a shape-retaining effect. Because of the presence of such fibers, the shape of the molded body is unlikely to collapse even though the activated carbon fiber, which is extremely brittle, is used.

Further, the molded adsorbent of the present invention can be manufactured in a good working environment as described below, and the quality is stable.

(1) In the case of dry molding, dust of activated carbon fibers is generated and the working environment is deteriorated. However, since the manufacturing method of the present invention is wet molding, it can be manufactured in a good working environment.

(2) Since a slurry in which activated carbon fibers and a heat-meltable synthetic resin are uniformly dispersed is forcibly sucked and molded by using a molding die, a molding having a large bulk density, that is, a dense three-dimensional structure is formed. The body is obtained. Although it has a dense three-dimensional structure, it has good air permeability and water permeability, and an adsorbent with stable quality can be obtained.
In particular, when a heat-meltable synthetic resin is used, a molded product having a high strength and a specific surface area not substantially reduced can be obtained.

Furthermore, when a non-thermofusible fiber is blended as the reinforcing material, the strength of the molded adsorbent is further improved and the handling becomes easier.

Further, when the heat-meltable synthetic resin is fibrous, the pores of the activated carbon are less likely to be blocked, which is more preferable.

The adsorbent of the present invention is effectively used for filtration of solid components in a liquid phase and a gas phase, adsorptive removal of trace impurities and harmful components, concentration by adsorption and desorption of useful components, and the like. More specifically, it removes iron rust, malodorous substances, free chlorine, etc. from tap water as a filter in a water purifier; smoke as a filter in an air purifier and an air conditioner,
It is used in a wide range of fields such as removal of malodorous substances and humidity control; solvent recovery in chemical plants, cleaning industry, etc .; removal of solid components in mineral oil and vegetable oil.

[0042]

EXAMPLES Hereinafter, the features of the present invention will be further clarified by showing examples and comparative examples, but the technical scope of the present invention is not limited to the examples.

The adsorbing performance of the shaped adsorbents obtained in the respective examples was almost the same as that of the unshaped activated carbon fiber.

Example 1 will be described with reference to FIG. 250 parts by weight of activated carbon fibers and 50 parts by weight of wood pulp are dispersed in 50,000 parts by weight of water in a water tank 3, beaten until the fiber length of both becomes 0.1 to 5 mm, and then polyvinyl chloride having a concentration of 0.5% by weight. Arco
100 parts by weight of an aqueous solution having a softening point of about 60 ° C. was added to obtain a uniform slurry-2.

Then, blind flanges 5 and 6 are attached to both ends, and a cylindrical mold 1 (outer diameter 29 mm, length 2470 mm) having a large number of suction holes on the peripheral surface of the core 4 is placed in the water tank 3. The slurry is sucked from the inside of the core body 4 by a suction pump (not shown) through a suction hose 7 attached to the blind flange 6 and immersed in the above-mentioned structure around the core body 4 of the mold 1. After attaching the aqueous slurry, the formed hollow cylindrical body (inner diameter 29 mm, outer diameter 60 mm, length 24)
70 mm) was removed from the mold and heat-dried at 140 ° C. for 120 minutes.

The dimensions of the molded adsorbent having the paper-making structure thus obtained are as follows: inner diameter 28.9 mm, outer diameter 59.9 mm, length 2
468 mm, its physical property is a density of 0.222 g / c
m ³ , air permeability 78 sec / 300 cc (measured according to JIS P 8117 except that the diameter of the passage surface was 10 mm), and filtration rate 168 sec / 100 cc (measured according to JIS P 3801).

Example 2 150 parts by weight of activated carbon fiber, 40 parts by weight of glass fiber and 10 parts by weight of polyacrylonitrile fiber having a softening point of about 80 ° C. were dispersed in 5000 parts by weight of water, and each fiber length was 0.1 to 0.1.
After beating up to 5 mm to obtain a uniform slurry, a hollow cylindrical molded body was prepared in the same manner as in Example 1, and the temperature was 130 ° C.
And heated for 120 minutes to obtain a shaped adsorbent of the present invention.

The dimensions of the molded adsorbent having a papermaking structure thus obtained are as follows: inner diameter 29.2 mm, outer diameter 60.2 mm, length 2
468 mm, its physical properties are basis weight 2560 g /
m ² , thickness 15.5 mm, density 0.165 g / cm ³ ,
Air permeability 22sec / 300cc (measured in the same manner as in Example 1),
Filtration speed 40 sec / 100 cc (measured in the same manner as in Example 1)
Met.

The weighing is calculated by dividing the weight of the molded product by the average area π (inner diameter + outer diameter) / 2 × length of the side surface. The product weight is 886g and the area is π × (2.92+
The above value was obtained because 6.02) /2×246.8=3466 cm ² .

Example 3 The polyvinyl alcohol used in Example 1 was replaced with 10 parts by weight of polyacrylonitrile fiber having a softening point of about 80 ° C., and no wood pulp was used, and the core 4 was used.
A cylindrical molded body was obtained in the same manner as in Example 1 except that the length was set to 500 mm. The bulk density of the obtained molded body was 0.18 g / cm ³ . Although the molded product had a lower strength than the molded product obtained in Example 2, it could be sufficiently used as an adsorbent for a water purifier or the like.

Comparative Example 1 An aqueous slurry was prepared in the same manner as in Example 2 except that polyacrylonitrile fiber was not used, and was then molded in the same manner as in Example 1. The molded product had insufficient strength. Then, it collapsed immediately.

[Brief description of drawings]

FIG. 1 is a schematic view showing a suction molding method of a molded body of the present invention.

[Explanation of symbols]

 1 Mold 2 Slurry 3 Water Tank 4 Core 5 Blind Flange 6 Blind Flange 7 Suction Hose

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minoru Izawa Minorai, Mino-shi, Gifu 291 Mitani Bureau, Minatara, Kamiuchi (72) Inventor, Hiroshi Nagata 5-chome, Hirano-cho, Higashi-ku, Osaka-shi, Osaka Osaka Gas Co., Ltd. (72) Inventor Yoshitaka Middle East, 5-1, Hirano-cho, Higashi-ku, Osaka City, Osaka Prefecture Osaka Osaka Gas Co., Ltd. (72) Inoue, Noriyuki, 5-chome, Hirano-cho, Higashi-ku, Osaka City, Osaka Prefecture Osaka Osaka Gas Co., Ltd. (56) References JP-A-55-6576 (JP, A) JP-B-46-7604 (JP, B1)

Claims (4)

[Claims] 1. An activated carbon fiber and a heat-meltable synthetic resin are contained, and the content of the heat-meltable synthetic resin is 0.2 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of the activated carbon fiber,
An integrally formed molded adsorbent having a three-dimensional structure having a papermaking structure in which activated carbon fibers are randomly bonded and held by a hot-melt synthetic resin. 2. The molded adsorbent according to claim 1, wherein the content of the heat-meltable synthetic resin is 0.2 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the activated carbon fiber. 3. The molded adsorbent according to claim 1, further comprising a non-thermofusible fiber. 4. The molded adsorbent according to claim 1, 2 or 3, wherein the heat-meltable synthetic resin is fibrous.