JPH03167390A - Activated carbon fiber sheets and filters - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an activated carbon fiber sheet with excellent processability, which is obtained by mixing activated carbon fibers and microfibrous cellulose disintegration products and by ordinary wet papermaking.

[Prior Art] In recent years, foul odors and toxic gases such as organic solvents have been increasingly discussed as pollution problems. Adsorptive substances are used as a means to prevent these problems, and active carbon fibers are being rapidly developed because of their extremely high gas adsorption speed.

When activated carbon fiber is used in the form of a sheet, the activated carbon fiber itself does not have self-adhesive properties, so a binder is required to give the sheet its shape. As the binder, various solution-type and emulsion-type liquid binders and fibrous binders are generally used.

The use of a liquid binder is not preferred because it blocks the pores of the activated carbon fibers and reduces the adsorption capacity.

The use of a fibrous binder requires a large amount of fibrous binder to prevent the activated carbon fibers from falling off and to obtain a sheet with sufficient strength, which reduces the content of activated carbon fibers in the sheet. Common fibrous binders include cellulose fibers such as softwood bleached pulp.
When contained in the sheet in an amount that provides sufficient sheet strength,
It is inevitable that the sheet will become flammable.

Also, Special Publication No. 59-35341 and Special Publication No. 59-51
As shown in Publication No. 432, when processing into a honeycomb shape, corrugation workability is required, and the sheet needs to have a bulk density above a certain level, and in order to increase the density, more binder is required. It is necessary to add carbon fiber, and in such a case, not only the amount of activated carbon fibers decreases, but also the air permeability of the sheet may deteriorate.

Activated carbon fibers have a fast adsorption rate and excellent adsorption ability for various vapors and gases, but they have poor adsorption ability for acetaldehyde, ammonia, carbon dioxide, and the like. It also has the disadvantage of being very expensive.

As a method of supplementing adsorption to these substances and increasing bulk density, there is a method of incorporating adsorbent particles or substances. However, a drawback of this method is that when powder is added internally to the sheet, it interferes with the adhesion between the binder and the activated carbon fibers, resulting in a significant decrease in sheet strength. Furthermore, powder may fall off and cause contamination.

As described above, it is difficult to achieve both improvement in sheet strength and processability and sheet adsorption properties.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned conventional problems, and by blending a very small amount of a specific fibrous binder with activated carbon fibers, it is possible to The object of the present invention is to provide a high-strength sheet, an adsorbent sheet that is non-combustible and has good processability, and a filter manufactured using the sheet.

[Means for Solving the Problems] The present inventor conducted extensive research in order to solve the above problems. As a result, as a binder for activated carbon fiber, 0.5
By using % to 30% microfibrous cellulose, a high-strength sheet can be obtained without impairing the adsorption capacity of activated carbon fibers, and it can also be processed into a honeycomb structure suitable for filters. I found out. Furthermore, the present invention was completed by discovering that microfibrous cellulose can contain zeolite, activated alumina, acid clay, silica gel, and diatomaceous earth in the sheet while maintaining sheet strength.

That is, the present invention is an activated carbon fiber sheet containing activated carbon fibers and microfibrous cellulose.

It is also an activated carbon fiber sheet containing activated carbon fibers, microfibrous cellulose, and an adsorbent substance.

In the present invention, an activated carbon fiber sheet is obtained by making a paper using a wet papermaking method using an aqueous slurry made of activated carbon fibers and microfibrous cellulose, and then heating and drying the paper.

The activated carbon fiber sheet described above can be used as a filter, and can be processed into a honeycomb structure and used as a filter.

The present invention will be described in detail below.

The activated carbon fiber used in the present invention can be selected depending on the purpose such as specific surface area and adsorption capacity, but any activated carbon fiber can be selected as long as it is dispersible in water. If it is difficult to disperse, a sticky agent or a dispersant may be added as appropriate and stirred. Average fiber length is 9.05 mm to 15
mm, preferably 0.5 mm to 10 mm. 0.
If it is less than 0.05 mm, the breathability of the sheet will decrease, and if it is less than 15 mm.
If the length is longer than m, dispersion in water will be poor.

The microfibrous cellulose used in the present invention is JP-A-56-1
As disclosed in Publication No. 00801, microfibrillation is performed using a homogenization device, unlike the treatment using a refiner used in general paper manufacturing processes. That is, when a slurry of cellulose dispersed in water is passed through an orifice with a pressure difference of 200 tgl/ad or more before and after the slurry at high speed, and the speed is immediately decelerated to apply shear force to each particle of the slurry, the cellulose The fibers are vertically divided in the direction of the fiber axis to form microfibrillar shapes. This product was obtained by repeating this process. A specific example is microfibrillated cellulose (MF C-100, manufactured by Daicel Chemical Co., Ltd.)
etc. can be mentioned.

Microfibrous cellulose has a fine fiber diameter (0.7 μm or less) that cannot be obtained by beating treatments such as finers, so the bonding ability between fibers is extremely large, and it can be mixed in small amounts with activated carbon fiber. You can get a strong sheet just by doing this. In addition, microfibrous cellulose easily intertwines with activated carbon fibers, synthetic fibers, natural fibers, or inorganic fibers, which makes the wet paper formed on the wire of the paper machine strong, making it difficult to proceed to the next process. It is easy to transfer and can be efficiently manufactured using ordinary papermaking equipment.

The sheet is obtained by uniformly dispersing and mixing the above-mentioned microfibrous cellulose and activated carbon fibers in water, making paper using an ordinary paper machine, and drying.

The amount of fine fibrous cellulose is 0.0% based on the weight of the sheet.
It is 5% to 30%, preferably 5% to 20%. Microfibrous cellulose is 0. If it is less than 5%, the strength of the sheet will be weak, and if it is more than 30%, the drainage properties of the slurry will be poor, which is not preferable in the papermaking process.

The adsorbent material used in the present invention is selected from zeolite, activated alumina, acid clay, silica gel, diatomaceous earth, and particulate activated carbon, and one or more of them may be used simultaneously. The finer the particle size, the better from the adsorption performance and the bonding state to microfibrous cellulose, and approximately 10
It is preferable that the 0 mesh passing section is 95% or more.

The amount of the above-mentioned adsorptive material is not more than 4 times, preferably not more than 3 times the amount of microfibrous cellulose. If it exceeds 4 times, the yield during paper making will be poor and particles will fall off from the sheet after drying. Further, the amount is 1% to 50%, preferably 1% to 30%, based on the weight of the sheet. If it exceeds 50%, the sheet strength will decrease significantly.

If necessary, the activated carbon fiber sheet described above may be treated with a water repellent by spraying, coating, impregnating it with a water repellent, and drying it. Alternatively, paper may be made by mixing a sizing agent with the slurry.

If necessary, the activated carbon fiber sheet can be made by mixing other natural fibers, synthetic fibers, and inorganic fibers. Examples of natural fibers include wood pulp, hemp pulp, and cotton pulp; examples of synthetic fibers include rayon fibers, polyester fibers, polyamide fibers, polyvinyl alcohol fibers, polyolefin fibers, and polyacrylonitrile fibers; examples of inorganic fibers include Examples include ceramic fibers, rock wool fibers, sepiolite, and glass fibers. It is also possible to mix an inorganic filler and make paper. Furthermore, it is also possible to contain chemical deodorants and natural/synthetic fragrances. However, these contents must not be in a range that inhibits the performance of the sheet of the present invention.

The activated carbon fiber sheet, which is a mixture of activated carbon fiber and microfibrous cellulose, can be easily cut with a cutter, slitter, etc., and can be incorporated into a unit and used as a filter. In addition, even if corrugated, it will not be damaged, and one-sided or double-sided corrugated cardboard can be made, stacked so that the ridge lines of the corrugations are parallel or perpendicular, or wrapped in a cylindrical shape to form a honeycomb structure. It is particularly effective to use it as

[Function] The activated carbon fiber sheet of the present invention uses microfibrous cellulose as a binder for the activated carbon fibers, thereby creating a high-strength sheet that does not block the pores of the activated carbon fibers with an unprecedentedly small amount of binder. It functions effectively as a filter with a large adsorption capacity for bad odors, solvents, etc. Additionally, a honeycomb structure is created by applying corrugated processing, which effectively acts as a filter.

[Example] The present invention will be specifically explained with reference to Examples below, but the present invention is not limited to these Examples.

In the examples, all parts and percentages are by weight.

Examples 1 to 3 Activated carbon fiber (manufactured by Nippon Riki Inol Co., Ltd., specific surface area 1500
rrr/g, benzene adsorption capacity 530 ■/g) was added to water to adjust the concentration to 0.3%, and after dispersing with an Sv type reciprocating stirrer (manufactured by Shimazaki Manufacturing Co., Ltd., Agitator), fine fibrous cellulose (Daicel MFC-100 (manufactured by Kagaku Co., Ltd.) was added and mixed while stirring with an agitator. At this time, the mixing ratio of activated carbon fiber and MFC-100 was 95/5, 90/10, 8
It was prepared by changing three levels to 0/20. Next, water was added to the slurry to dilute each to 0.1%, and the dry weight was 70g.
/rrr sheet was made into paper using a square hand paper machine (wire mesh 80 mesh - wire mesh size 25 cm x 25 cm), pressed and dried to obtain an activated carbon fiber sheet.

Comparative Examples 1 to 4 Softwood bleached pulp (N
B K P, freeness CSF 185 m1), sepiolite (manufactured by Mitsui Mining Co., Ltd.), polyester binder fiber (manufactured by Unitika Co., Ltd., core-sheath type Melty #40808D, fiber diameter 4 denier fiber length 5 mm), hot water soluble PVA fiber (
Vinylon VPB-105 (manufactured by Kuraray Co., Ltd., fiber diameter: 2 denier, fiber length: 3 mm) was added and mixed. Mixing ratio is PV
A fiber was prepared at 90/10, and the other fibers were prepared at 70/30, and a sheet was obtained by the above method.

As mentioned above, the measurement results of the physical properties of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1. Items include basis weight, thickness, tensile strength, breaking length,
Benzene adsorption capacity (JIS-K14l7), Smoostar air permeability (manufactured by Toei Electronics Co., Ltd., Smoostar, type SM-
6A).

In addition, the presence or absence of shedding of activated carbon fibers during cutting with scissors and corrugation processing, and the combustibility of the sheet were investigated.

The above results are shown in Table 1.

Examples 4 to 6 MFC-100 and synthetic zeolite (manufactured by Tosoh Corporation, Zeorum F-9, powder, 100 mesh) were added and mixed to a slurry of activated carbon fibers dispersed in the same manner as in Examples 1 to 3. Activated carbon fiber/MFC-100/Zeolam F-
The mixing ratio of 9 is 85/1 0/1 5, 6 0/1 0/
A sheet was obtained by the above method with three levels of adjustment: 30, 90/1, and 0/30.

Comparative Examples 5 and 6 NBKP (CSF 185ml) and Zeorum F were added to a slurry of activated carbon fibers dispersed in the same manner as Examples 1 to 3.
-9 was added and mixed. The mixing ratio of activated carbon fiber/NBKP/Zeolam F-9 is 5 0/3 0/20, 7 0/3
Two levels of adjustment were made at 0/20, and a sheet was obtained by the above method.

As mentioned above, the basis weight, thickness, and tensile strength of the sheets of Examples 4 to 6 and Comparative Examples 5 and 6 were measured. Also, the presence or absence of shedding of activated carbon fibers and zeolite was examined. The above results are shown in Table 2.

As is clear from Table 1, microfibrous cellulose exhibits an excellent binder effect even in small amounts. PVA fibers also exhibit strength comparable to that of microfibrous cellulose, but there is a significant decrease in the amount of benzene adsorbed, which is thought to be due to clogging of the pores on the surface of the activated carbon fibers. Further, even during cutting and corrugation processing, the activated carbon fibers did not fall off as was the case with other binders. Further, since microfibrous cellulose exhibits a binder effect in a small amount, the sheet using NBKP is flammable, whereas the sheet of the present invention exhibited self-extinguishing properties.

Examples shown in Table 2 and Example 2 shown in Table 1 show that when microfibrous cellulose is used, the decrease in strength is small even when zeolite is contained.

On the other hand, as shown in Comparative Examples 5 and 6 and Comparative Example 1 in Table 1, NBKP showed a large decrease in strength compared to microfibrous cellulose even when the zeolite content was low. moreover,
There was also significant zeolite falling off during processing.

Example 7 A fluorine-based water repellent (0.18% concentration) was added to the sheet of Example 6.
Impregnated with Sumitomo Chemical Co., Ltd., Sumilettes FP-210),
Water was squeezed out, dried, and treated to make it water repellent. The amount of water repellent applied was 0.646% of the weight of the sheet. When I dropped water on it with a pipette, it repelled the water and showed a water-repellent effect. Compared to the sheet of Example 6, almost no decrease in adsorption capacity was observed.

[Effects of the Invention] The activated carbon fiber sheet of the present invention consists of activated carbon fibers and microfibrous cellulose. Compared to activated carbon fiber sheets using conventional binders, it has sufficient strength with a small amount of binder, does not block the pores of activated carbon fibers, has high adsorption properties, does not cause activated carbon fibers to fall off, and is breathable. I was able to get a good seat. In addition, it has high strength and good workability, so it was possible to process a honeycomb structure and use it as a filter.

Furthermore, a sheet containing an adsorbent substance could be obtained without reducing the sheet strength.

Claims (5)

[Claims] (1) An activated carbon fiber sheet containing 0.5% to 30% of microfibrous cellulose and activated carbon fibers. (2) 1 selected from adsorbent materials such as zeolite, activated alumina, acid clay, silica gel, diatomaceous earth, and granular activated carbon.
The activated carbon fiber sheet according to claim 1, which contains at least one kind of substance in a range of 1% to 50%. (3) The activated carbon fiber sheet according to claim 1 or 2, which is formed into a honeycomb-like structure. (4) A filter comprising the activated carbon fiber sheet according to claim 1 or 2. (5) The filter according to claim 4, which is formed into a honeycomb-like structure.