JPH0627373B2 - Activated carbon fiber manufacturing method - Google Patents

Description

The present invention relates to fibrous activated carbon, that is, activated carbon fiber,
More specifically, for example, household and commercial air purifiers and water purifiers, organic solvent recovery devices, ozone removal for copiers, general-purpose masks and gas masks, medical adsorbents, separation of chemicals and industrial raw materials, The present invention relates to a method for producing activated carbon fiber, which has a wide range of useful cured novolac resin fibers as precursors, and which contains a large number of pores with a pore size of 40Å or more .

<Prior art> Activated carbon fibers have superior adsorption ability compared to granular or powdery activated carbon, have a fast adsorption rate, and because they are fibrous, they can be used for cloth, paper,
It has the advantage that it can be processed into various forms of fiber structures such as felt, but its pore structure has a large proportion of fine pores with a pore size of 40Å or less, so that it can be used, for example, for adsorption of polymeric substances. Are unsuitable and have the drawback of limited application. The activated carbon fibers include those having a polyacrylonitrile fiber as a precursor, those having a cellulosic fiber as a precursor, and those having a cured novolac resin fiber as a precursor, but in any case, as described above. Is activated carbon fiber with a pore structure easy to obtain, or has a pore size of 40Å
It is known that it is difficult to obtain the above activated carbon fiber containing many pores. For example, in the case of the pore structure of generally used activated carbon fiber having a specific surface area of about 1800 m ² / g, which uses cured novolac resin fiber as a precursor, 98% or more of the pore volume is due to fine pores having a pore diameter of 40 Å or less. is there. These conventional activated carbon fibers having only developed fine pores have the above-mentioned drawbacks. Therefore, some methods for producing activated carbon fibers having relatively large pores are known for the purpose of improving them. There is.

For example, as in JP-A-59-172230, there is a method in which a certain amount of metal ions are supported on a raw material fiber and then carbonization is activated.
However, in this case, the metal ions are substantially attached only to the surface of the raw material fiber, and it is almost impossible to permeate the inside of the fiber. After carbonization of the metal ion-supporting raw material fiber, for example, when activated by water vapor, water vapor diffuses inside the fiber and develops pores earlier, and the catalytic action of the metal ions acts on the surface of the carbon of the surface portion. The oxidation reaction progresses rapidly, resulting in fiber thinning. That is, in the above method, while the increase in the pore volume is insufficient,
That is, there is a drawback that the yield of the activated carbon is lowered while the performance of the activated carbon is insufficient. Therefore, even if activated carbon fibers having relatively large pores are obtained, the yield is low and it is disadvantageous in terms of cost.

<Problems to be Solved by the Invention> Therefore, a first object of the present invention is to provide a method for producing an activated carbon fiber having a large pore diameter of 40 Å or more and capable of controlling the pore diameter in a high yield. It is in.

That is, according to the present invention, an uncured novolak resin contains at least one compound selected from compounds of Group IIA elements of the Periodic Table, transition metals, and potassium, and the resulting cured novolak is used for curing after melt spinning. The above compound or the metals in the above compound are uniformly dispersed and contained inside the resin fiber. Activated carbon fibers containing a large number of pores having a pore diameter of 40 Å or more can be produced in good yield by carbonizing the cured novolac resin fiber and then activating it with steam or performing steam activation simultaneously with carbonization. Occupy in all pores by appropriately changing or increasing / decreasing the kind and amount of the compound 4
It is possible to increase or decrease the proportion of pores having a pore diameter of 0Å or more. That is, the pore size can be controlled.

Although the reason why the activated carbon fiber containing a large number of pores having a relatively large pore size is produced in good yield by the present invention is not clear,
It is considered that, in the process of activation progressing while water vapor diffuses into the fiber, it encounters the core of the metal in the middle of the process and is subjected to the catalytic action of the metal around it, and the oxidation reaction proceeds earlier than other parts. To be The amount of the metals on the surface of the fiber is extremely small as compared with the case where the metal is simply supported on the fiber, which is considered to be the reason why the production can be performed with a high yield.

As another known method, for example, JP-A-58-18418 has a surface area of 30 to 1200 m ² / g and a pore diameter of 30 to 30.
There is a method of producing an activated carbon fiber containing many pores of 30 Å or more by supporting a metal compound on a carbonaceous fiber having a pore volume of 0 Å of 0.1 cc / g or less and then performing an activation treatment. However, also in this case, in order to support the metal compound, a method such as immersing the carbonaceous fiber in an aqueous solution of the metal compound and then drying it, or spraying and drying the carbonaceous fiber is practically applied only to the surface of the carbonaceous fiber. The possibility that these metal compounds may adhere is the same as in the above-mentioned known method. Therefore, this method not only has the drawback that there is a risk of lowering the yield, but the carbonaceous raw material before supporting the metal compound is already carbonized and activated under certain conditions,
Having certain pores is an essential condition, and there is an unavoidable drawback due to the complexity of the process.

Therefore, a second object of the present invention is to provide a method for extremely easily producing activated carbon fibers which can control the pore size and which contains a large number of pores having a pore size of 40 Å or more.

<Means for Solving the Problems> That is, according to the present invention, at least one selected from compounds of Group IIA elements of the Periodic Table, transition metals and potassium is simply added before the step of melt spinning an uncured novolak resin. It is only necessary to include the compound of No. 1, and it is possible to extremely easily uniformly disperse the metal compound inside the fiber without complicating the manufacturing process. Therefore, by activating the carbonization of the metal compound, pores having a pore diameter of 40 Å or more can be formed. Activated carbon fibers containing a large amount can be produced.

The method for producing activated carbon fibers according to the present invention comprises 0.01 to 10 parts by weight of at least one compound selected from compounds of Group IIA elements of the Periodic Table, transition metals and potassium per 100 parts by weight of uncured novolac resin. It is characterized in that the cured novolac resin fiber obtained by curing after melt spinning is activated by carbonization.

The uncured novolac resin used in the present invention is generally known, for example, in addition to phenol, alkylphenols and other substituted phenols, polyvalent phenols and aldehyde sources such as formaldehyde and paraformaldehydes as essential raw materials. It is obtained by reacting under acidic conditions by a conventional method.

As the compound of the Group IIA element of the periodic table, the transition metal and the potassium used in the present invention, inorganic compounds such as magnesium carbonate, iron hydroxide, potassium chloride and ammonium metavanadate can be used. Organic compounds such as salts of organic acids such as calcium acidate and potassium salicylate, and metal coordination compounds such as ferrocene, vanadinocene, and monochloropentamminecobalt chloride are more advantageous. This is because the latter is more compatible with the uncured novolac resin than the former and is likely to be uniformly contained, and it is convenient when a large amount of those having a relatively low melting point is directly mixed. As long as it can be uniformly contained, it may be dissolved in water or a solvent regardless of whether it is an inorganic type or an organic type, and the method of containing the same is not limited. The compound used in the present invention may be added to the uncured novolac resin at any time before melt spinning, and therefore, the novolac resin is still a low molecular weight compound during the reaction and may be in a liquid state. There is no such thing.

The content of the above compound is 0.01 to 10 parts by weight based on 100 parts by weight of the uncured novolac resin according to the present invention. If the amount is less than 0.01 parts by weight, the effect is extremely small and it is difficult to obtain activated carbon fiber containing many pores having a pore size of 40 Å or more.
If it is 10 parts by weight or more, melt spinning becomes difficult, and at the same time, even if spinning is possible, the yield of the activated carbon fiber obtained is extremely decreased, which is not preferable.

Thus, after melt-spinning the uncured novolac resin containing the above compound, for example, 15 to 20% by weight of hydrochloric acid and 8 to
The cured novolac resin fiber is obtained by immersing in a mixed aqueous solution of 25% by weight of aldehydes and gradually raising the temperature and holding at a temperature of 90 ° C. or higher for several hours. To activate this cured novolac resin fiber by carbonization, generally known activation such as steam, carbon dioxide, activation by an oxidizing gas such as air, or chemical activation by zinc chloride or the like may be carried out according to a conventional method, and is not particularly limited. Not a thing. As described above, the activated carbon fiber using the cured novolac resin fiber as a precursor, which is obtained very easily and in good yield without the complexity of the process, contains a large number of pores having a pore diameter of 40Å or more, and the pore diameter is controlled. It was a thing.

Examples of specific experimental aspects of the present invention will be shown below. Parts or% are by weight unless otherwise specified. The yield was based on the cured phenolic resin fiber before carbonization activation. Also, the compounds in this patent may be single or mixed.

<Example> Example-1 12 kg of phenol, 7.3 kg of 42% formalin and 35 g of silicic acid were placed in a reaction vessel of 30 and reacted at a reflux temperature for 4 hours, followed by vacuum concentration to obtain an uncured novolak having a curing point of 110 ° C. Resin 10.2 Kg was obtained. While the uncured novolac resin was still in a molten state in the reaction can, 12 g of monochloropentamminecobalt chloride was added, uniformly mixed and dissolved to contain, and then taken out. The obtained cobalt-containing uncured novolac resin has a number of holes of 252 and a hole diameter of 0.2 mmφ.
Melt-spinning was carried out at a speed of 520 m / min using the spinneret of No. 1 to obtain a cobalt-containing uncured novolac resin fiber. The novolac resin fiber was immersed in a mixed aqueous solution of 17.5 wt% hydrochloric acid and 12.5 wt% formaldehyde, gradually heated to 95 ° C over 2 hours, and then held at a temperature of 95 to 98 ° C for 8 hours. A cobalt-containing cured novolac resin fiber was obtained. This cured novolac resin fiber is put into a quartz tube with an inner diameter of 70 mmφ, nitrogen is fed at a rate of 450 ml / min into warm water which has been adjusted to 80 ° C. in advance, and this mixed gas of nitrogen and water vapor is introduced into the quartz tube. While activating the carbonization.
The temperature rising rate was 5 ° C./min, and when the temperature was raised to 25 ° C., introduction of the mixed gas was started. Furthermore, the temperature was raised to 900 ° C. at the same temperature rising rate, and the temperature was maintained for 40 minutes, then cooled while introducing only nitrogen to obtain activated carbon fibers.

Example-2 An activated carbon fiber was obtained by the same procedure as in Example-1, except that the metal compound was not added to the uncured novolac resin. The total pore volume of the obtained activated carbon fibers, the pore volume of pores having a pore diameter of 40 Å or more, and the ratio thereof to the total pore volume are shown in Example-
The results are shown in Table 1 together with the results of the activated carbon fiber obtained in No. 1.
The total pore volume was calculated based on the adsorption amount at the relative pressure of 1 on the adsorption isotherm after nitrogen adsorption at the boiling point of liquid nitrogen. Similarly, the pore volume of pores with a diameter of 40 Å or more was calculated from the nitrogen adsorption isotherm by the Cranston-Inkley method (Kei Itomicho "Adsorption" Kyoritsu Shuppan).

Example-3 12 kg of phenol, 4.0 kg of 85% paraformaldehyde,
30 g of silicic acid was charged into 30 reactors, reacted at reflux temperature for 2 hours, and then solid content, that is, novolac resin content 51.8%
An uncured novolak resin reaction mixture of was obtained. To the reaction mixture, 94 g of potassium salicylate was added, mixed and contained, and vacuum concentrated to obtain a potassium-containing uncured novolak resin having a softening point of 105 ° C. This resin was treated under the same spinning conditions and curing conditions as those described in Example-1 to obtain cured novolac resin fibers, which were placed in a quartz tube and the holding temperature was set to 80.
Activated carbon fiber was obtained by performing the activation treatment under the same activation conditions as in Example 1 except that the temperature was set to 0 ° C. for 40 minutes.

Example-4 30 g of cured phenolic resin fiber KF-0270M (manufactured by Gunei Chemical Industry Co., Ltd.) and 1000 ml of 0.5% cobalt chloride aqueous solution
After soaking at room temperature for 6 hours and drying, a cured phenol resin fiber carrying cobalt chloride was obtained. Example 1 except that the fibers were put into a quartz tube and the holding temperature was 800 ° C. for 40 minutes.
The activation treatment was performed under the same activation conditions as above to obtain activated carbon fibers. Table 2 shows the pore structure and yield of the activated carbon fibers obtained in Example-3 and Example-4.

Example-5 An activated carbon fiber was obtained in accordance with Example-1 except that 450 g of ferrocene was added to the uncured novolac resin.
Pore diameter 40 in the total pore volume of the obtained activated carbon fiber
The ratio of the pore volume of Å or more is 43.6% and the yield is 2
It was 1.9%.

Example-6 Activated carbon fibers were obtained in accordance with Example-1 except that 8 g of diaminebis (ethylenediamine) nickel chloride was added to the uncured novolac resin. The ratio of the pore volume of pores having a pore diameter of 40 liters or more in the total pore volume of the obtained activated carbon fiber was 33.2%, and the yield was 26.1%.

Example-7 Activated carbon fiber was obtained according to Example-6 except that the amount of diaminebis (ethylenediamine) nickel chloride of Example-6 contained was 160 g. The ratio of the pore volume of pores having a pore diameter of 40 liters or more in the total pore volume of the obtained activated carbon fiber was 57.5%, and the yield was 14.9%.

<Effects of the Invention> As described above, the activated carbon fiber according to the present invention is very easily obtained in good yield and has a controlled pore size including many pores having a pore size of 40Å or more, and is effective for adsorption of polymer substances. Can be used for

Claims (1)

[Claims] 1. After melt spinning, 0.01 to 10 parts by weight of at least one compound selected from compounds of Group IIA elements of the Periodic Table, transition metals and potassium is contained in 100 parts by weight of uncured novolac resin. A method for producing an activated carbon fiber, which comprises activating carbonization of a cured novolac resin fiber obtained by curing.