JP4566425B2 - Carbon fiber and method for producing activated carbon fiber - Google Patents

Description

【００１７】
実施例７及び比較例３
実施例５で使用したフェノール繊維のクロスを１００℃で３時間酸素ガス雰囲気中で加熱し、酸素含有量を２１％とした。これを窒素ガス雰囲気中で３００℃〜８００℃まで昇温して炭化処理し、さらに９００℃の水蒸気ガス雰囲気中で賦活し、活性炭繊維クロスを得た（実施例７）。実施例７と同じクロスを実施例７と同じ条件で炭化、賦活処理した。酸素含有量は１４％のままであった（比較例３）。これらのクロス各々１ｍ²から５箇所無作為にサンプリングし、物性を評価した。結果を表２に示すが、本発明の方法により製造した活性炭繊維は高品位であることが明らかである。
【００１８】
【表２】

【００１９】
【発明の効果】
本発明により、１８−２４重量％の酸素を付着させたフェノール繊維を炭化することを特徴とする炭素繊維の製造方法及び該炭素繊維をさらに賦活処理する活性炭素繊維の製造方法を提供することができる。本発明によれば、炭素繊維及び活性炭素繊維は強度に優れ、高収率で製造することができるので、産業上の有用性が大きい。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing carbon fibers and activated carbon fibers. More specifically, the present invention relates to a carbon fiber and an activated carbon fiber production method capable of producing a carbon fiber excellent in strength and an activated carbon fiber using a phenol fiber containing a specific amount of oxygen as a raw material in a high yield.
[0002]
[Prior art]
Conventionally, many methods for producing phenol fibers are known. For example, a method for heating a resol type phenol resin containing an alkali (earth) metal and curing it in flowing propylene glycol (Japanese Patent Publication No. 48-43570). No.), a method of heat-treating a cured novolak fiber obtained by subjecting an uncured novolak fiber obtained by melt spinning a novolak resin with an aldehyde to a non-oxidizing atmosphere (Japanese Patent Laid-Open No. 53-94626), uncured A method of heat-treating a cured novolak resin fiber obtained by adding polyvinyl butyral to a novolak resin and curing it after melt spinning (Japanese Patent Laid-Open No. 9-13223), reacting phenols and aldehydes in the presence of a basic catalyst The solid resol-type phenolic resin obtained by heating is melted and the spinning nozzle is operated by the traction of the heated air flow. It spun and fiberizing by, including how to insoluble and infusible by heating in an acidic gas atmosphere (JP-A-9-132818) is known the fibers.
[0003]
The phenol fiber described above is a carbon fiber, and by activating it, it can be made into activated carbon fiber, and its applications are further expanded for water purification, deodorization, electrical materials, etc. As the activated carbon fiber, the cured novolac fiber obtained by curing the uncured novolak fiber with aldehydes is heated to 700 ° C. in an atmosphere of a mixed gas composed of water vapor and inert gas, and the activated carbon fiber is heated. This method is known from Japanese Patent Publication No. 58-51527. An example in which a phenol-based activated carbon fiber is applied to an electric double layer capacitor is disclosed in Japanese Patent Application Laid-Open No. 62-222617. And this patent gazette describes that this activated carbon fiber carbonizes raw material fiber to make carbon fiber, and activates this to make activated carbon fiber.
[0004]
[Problems to be solved by the invention]
Phenol fibers are already infusible fibers, but as described above, carbon fibers are obtained by carbonizing a phenol fiber raw material, and activated carbon fibers are obtained by further activating the carbon fibers. Is common. However, when carbonizing the phenol fiber, tar and lower carbides are generated particularly by the decomposition reaction during carbonization, the yield of the carbon fiber is low, and the strength of the fiber is low. The activated carbon fiber is obtained by activating the carbon fiber, but similarly the yield is low, the strength of the fiber is small, and the quality is inferior. Accordingly, an object of the present invention is to provide a carbon fiber and a method for producing an activated carbon fiber that can be obtained in a high yield with excellent strength without such problems.
[0005]
[Means for Solving the Problems]
The present inventors have intensively studied to achieve the above object, and found that the above object is achieved by containing a specific amount of oxygen in the phenol fiber and suppressing the decomposition reaction during carbonization. It came to. That is, the present invention is a carbon fiber production method characterized by carbonizing a phenol fiber containing 18 to 24% by weight of oxygen. Another invention of the present invention is a method for producing activated carbon fibers, wherein a phenol fiber containing 18 to 24% by weight of oxygen is carbonized and further activated.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The phenol fiber used in the present invention may be one obtained by spinning and heat-treating a phenol resin, and specifically, a novoloid fiber (trade name: Kynol) obtained by spinning a novolak phenol resin. And resole fibers obtained by spinning a resole resin. The greatest feature of the present invention is that the phenol fiber raw material before carbonization contains 18-24% by weight of oxygen, but the oxygen content in the phenol fiber raw material depends on the raw material and the manufacturing method. Although it is different, it is usually less than 15%, so it is oxidized to bring the oxygen content of the phenol fiber raw material to a state of 18-24% by weight.
The oxidation treatment in the present invention is a treatment in which a phenol fiber raw material is brought into contact with oxygen and / or an oxygen-containing compound, a group having oxygen is formed in the phenol fiber raw material, and / or a crosslinking reaction is caused between phenol molecules. That is. As the gas used to make the atmosphere for the oxidation treatment, a gas containing oxygen may be used, but usually air is used. The temperature of the oxidation treatment is usually performed in the range of 100 to 300 ° C., but even in the case of 50 ° C. or less, the oxidation reaction can be advanced by means such as irradiation with ultraviolet rays.
[0008]
In order to measure the amount of oxygen in the phenol fiber, the following method can be used. That is, the amount of oxygen in the raw material is obtained by thermally decomposing phenol fiber in an inert gas atmosphere, converting oxygen in the raw material to carbon monoxide on a carbon catalyst, and measuring the concentration of the carbon monoxide. be able to. As an analyzer for measuring the concentration of carbon monoxide using such a principle, for example, an element analyzer MT-6 commercially available from Yanaco Analytical Co., Ltd., commercially available from Perkin Elmer Co., Ltd. A device such as the element analysis device 2400II may be used. According to the present invention, by oxidizing the phenol fiber and carbonizing the phenol fiber raw material containing a specific amount of oxygen, the carbon fiber that is less decomposed during the carbonization reaction and excellent in strength is obtained in a high yield. Obtainable. By further activating the carbon fibers thus obtained, activated carbon fibers excellent in strength and quality can be obtained in high yield.
[0009]
According to the present invention, carbon fiber or activated carbon fiber can be produced with a yield as high as 10 to 15% compared to the conventional case, and the obtained carbon fiber or activated carbon fiber is excellent in strength. Although the reason for this cannot always be explained clearly, the following reasons can be considered. Since the proportion of oxygen atoms in the phenol raw material indicates the proportion of organic functional groups such as hydroxyl groups, carboxyl groups, ester groups, etc. on the phenol surface, these functional groups contribute to the crosslinking of phenol molecules. Therefore, it is recognized that the weight yield of activated carbon production is improved when the oxygen atom ratio exceeds a certain value. Therefore, the oxygen molecule and the phenol molecule take a cross-linked structure, so that cyclization during carbonization occurs. It seems to contribute to the formation of the structure. However, if the proportion of oxygen atoms increases too much, the number of active sites during the cyclization reaction increases, which seems to inhibit the growth of the cyclized structure.
[0010]
In addition, sheet-like activated carbon fibers such as knit, non-woven fabric, felt, and cloth are required to be excellent in quality. Here, the quality indicates the primary, secondary, and three-dimensional uniformity of the sheet. Specifically, the physical properties such as the basis weight, thickness, and density are uniform, or the suspension, sagging, It means that there are no defects such as color spots. In the conventional phenol fiber, since the crosslinking is insufficient, an exhaust gas containing a tar component is generated during carbonization and / or activation, and a phenomenon in which the tar component is locally reattached to the phenol resin is observed. There was a difference in the carbonization degree and activation degree between the tar adhering part and the non-adhering part, and the quality was not necessarily excellent. However, according to the method of the present invention, the tar component in the exhaust gas is reduced, and the carbonization and / or activation reaction proceeds uniformly without being hindered, and a high-grade activated carbon fiber can be obtained.
[0011]
EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these. In Examples and Comparative Examples, physical properties were measured by the following methods.
(1) Oxygen content of phenol fiber: It was measured using an element analyzer MT-6 manufactured by Yanaco Analytical Industries.
(2) Weight yield: It was determined from the ratio of the weight of the phenol fiber subjected to each treatment to the weight of the untreated phenol fiber.
(3) Specific surface area: BET specific surface area determined from the amount of nitrogen adsorbed.
(4) Fiber strength: Measured according to JIS K 1477 Fibrous Activated Carbon Test Method 5.5 Tensile Strength.
[0012]
【Example】
Examples 1-2
Phenol fiber (Novoloid fiber manufactured by Nippon Kainol Co., Ltd., oxygen content: 15%) was heated in air at 280 ° C. for 30 minutes to make the oxygen content 24%. This was heated from 300 ° C. to 800 ° C. in a nitrogen gas atmosphere and carbonized to obtain carbon fibers (Example 1). Further, the carbon fibers were activated in a steam gas atmosphere at 900 ° C. to obtain activated carbon fibers. The results are shown in Table 1.
[0013]
Examples 3-4
Phenol fiber (Novoloid fiber manufactured by Nippon Kainol Co., Ltd., oxygen content: 13%) was irradiated with ultraviolet rays in air at 25 ° C. to adjust the oxygen content to 20%. In the same manner as in Examples 1 and 2, carbonization and activation treatment were carried out (Examples 3 and 4 respectively).
The results are shown in Table 1.
[0014]
Examples 5-6
Phenol fiber (Resol fiber manufactured by Saint-Gobain Co., Ltd., oxygen content: 14%) was heated at 200 ° C. in a mixed gas atmosphere with combustion gas exhaust gas / air of 1/1 to make the oxygen content 19%. In the same manner as in Examples 1 and 2, carbonization and activation treatment were performed (Examples 5 and 6 respectively). The results are shown in Table 1.
[0015]
Comparative Examples 1-2
The same phenol fiber (oxygen content 15%) as used in Example 1 was heated at 280 ° C. for 30 minutes in a nitrogen gas atmosphere. The oxygen content remained at 15%. This was carbonized and activated in the same manner as in Examples 1 and 2, and the results shown in Table 1 were obtained (Comparative Examples 1 and 2 respectively). When Examples 1-6 are compared with Comparative Examples 1-2, it is clear that the carbon fibers and activated carbon fibers obtained by the present invention are excellent.
[0016]
[Table 1]

[0017]
Example 7 and Comparative Example 3
The phenol fiber cloth used in Example 5 was heated in an oxygen gas atmosphere at 100 ° C. for 3 hours to adjust the oxygen content to 21%. This was heated to 300 ° C. to 800 ° C. in a nitrogen gas atmosphere and carbonized, and further activated in a steam gas atmosphere at 900 ° C. to obtain activated carbon fiber cloth (Example 7). The same cloth as in Example 7 was carbonized and activated under the same conditions as in Example 7. The oxygen content remained 14% (Comparative Example 3). Each of these crosses was sampled at random from 1 m ² to evaluate physical properties. The results are shown in Table 2, and it is clear that the activated carbon fibers produced by the method of the present invention are of high quality.
[0018]
[Table 2]

[0019]
【The invention's effect】
According to the present invention, it is possible to provide a carbon fiber production method characterized by carbonizing a phenol fiber to which 18 to 24% by weight of oxygen is attached, and an activated carbon fiber production method for further activating the carbon fiber. it can. According to the present invention, the carbon fiber and the activated carbon fiber are excellent in strength and can be produced in a high yield, so that the industrial utility is great.

Claims (2)

A method for producing a carbon fiber, characterized in that the phenol fiber is subjected to an oxidation treatment by irradiating the phenol fiber with an ultraviolet ray, 18-24% by weight of oxygen is contained in the phenol fiber , and the phenol fiber is carbonized. A method for producing activated carbon fiber , comprising subjecting a phenol fiber to oxidation treatment by irradiating with ultraviolet rays, containing 18-24 wt% oxygen in the phenol fiber, carbonizing the phenol fiber , and further activating the phenol fiber.