JP4153529B2 - Carbon fiber and method for producing activated carbon fiber - Google Patents

Description

  The present invention relates to a method for producing a composite fiber, producing a carbon fiber from the composite fiber, and a method for producing an activated carbon fiber.

Carbon fibers are widely used in various fields because they are excellent in properties such as strength, wear resistance, and elasticity. Such carbon fibers are usually made from fibers such as pitch fibers, acrylic fibers, phenol resin fibers, rayon fibers and the like, heated in an oxidizing atmosphere as necessary, and then in an inert atmosphere. Manufactured by high temperature treatment and carbonization.
An active carbon fiber is a fiber having a large specific surface area in which a large number of pores are formed. Activated carbon fibers are suitably used for adsorbents, electrodes for electric double layer capacitors, and the like by utilizing such characteristics. Such activated carbon fibers are produced by a method of further activating after carbonizing each of the above-mentioned fibers in the same manner as in the case of carbon fibers. Activation is a process for forming pores of activated carbon fibers, and is usually performed by a method of reacting with a specific gas or chemical under high temperature conditions. Activation is sometimes called activation.
In addition, as another method for producing carbon fiber or activated carbon fiber, a method using a fiber produced from a pyranose ring-based or lignin-based polymer material as a raw material has been studied (see Patent Document 1). .
JP 2002-38334 A

However, the conventional carbon fiber manufacturing method has a problem that the raw material fibers are burned out at a high rate in the carbonization process at a high temperature, and a sufficient carbon fiber yield cannot be obtained.
Further, when producing activated carbon fibers, it is necessary not only to carbonize the fibers at a high temperature but also to activate them, so that it has been more difficult to achieve a high activated carbon fiber yield.
Further, when carbon is activated and activated in order to produce activated carbon fiber, the fiber shape may be lost during carbonization and activation depending on the type of fiber. Even if activated carbon fibers having a good fiber shape are obtained, the specific surface area may be insufficient, or the total volume of mesopores that greatly affect the performance of activated carbon fibers may be small, The characteristics as carbon fiber may not be sufficient. In the present specification, pores having a pore diameter of 3 to 30 nm calculated from the nitrogen adsorption isotherm using an analysis method such as the BJH method are referred to as mesopores.

  The present invention has been made in view of the above circumstances, and can produce carbon fibers and activated carbon fibers at a high yield. In particular, activated carbon fibers can be produced at low cost with a large specific surface area and large total volume of mesopores. It is an object to provide a method that can be used.

As a result of intensive studies, the present inventors have conducted a solid-liquid separation after heating a mixture of bark and methanol and / or acetone as a raw material for producing carbon fiber or activated carbon fiber , and obtained a solvent from the resulting liquid. It was found that the above-mentioned problems can be solved by using a composite fiber obtained by spinning a bark extract composition obtained by removing water and a spinning stock solution containing a reaction product of the composition, and the present invention has been completed. .
The carbon fiber production method of the present invention is a carbon fiber production method comprising a step of producing a composite fiber and a step of carbonizing the produced composite fiber, wherein the step of producing the composite fiber comprises a spinning dope. Extraction of bark obtained by spinning and solidifying by discharging from the hole, and mixing the mixture of bark and methanol and / or acetone as the spinning stock solution, followed by solid-liquid separation and removing the solvent from the resulting liquid A mixed solution containing the composition and at least one fiber-forming polymer compound is used.
The mixed solution may further contain a thermosetting resin.
Further, as a spinning dope, a mixture of bark and methanol and / or acetone is heated and subjected to solid-liquid separation, and a reaction product of a bark extract composition obtained by removing the solvent from the obtained liquid , and at least one kind It is also possible to use a mixed solution containing the fiber-forming polymer compound.
The reaction product is preferably a reaction product obtained by reacting the bark extract composition with a thermosetting resin or aldehydes.
The thermosetting resin is preferably at least one selected from the group consisting of a phenol resin, a furan resin, an epoxy resin, a urethane resin, and a copolymer thereof.
The fiber-forming polymer compound is preferably at least one selected from the group consisting of cellulose diacetate, cellulose triacetate, polyacrylonitrile, polyvinyl butyral, polyvinyl acetate, polyamide, polyester, and copolymers thereof. .
The bark is preferably at least one bark selected from the group consisting of acacia, quebraco, and radiatapine.
The method for producing an activated carbon fiber according to the present invention includes a step of producing a conjugate fiber, and a method of producing an activated carbon fiber having a step of carbonizing and activating the produced conjugate fiber. A spinning process in which the spinning dope is discharged from the pores and solidified, and as the spinning dope, a mixture of bark and methanol and / or acetone is heated and solid-liquid separated, and the solvent is removed from the resulting liquid. A mixed liquid containing the obtained bark extract composition and at least one fiber-forming polymer compound is used.
As the spinning dope, a mixture of bark and methanol and / or acetone is heated and subjected to solid-liquid separation, and the reaction product of the bark extract composition obtained by removing the solvent from the obtained liquid , and at least one kind of A mixed solution containing a fiber-forming polymer compound can also be used.
The reaction product is preferably a reaction product obtained by reacting the bark extract composition with a thermosetting resin or aldehydes.
The thermosetting resin is preferably at least one selected from the group consisting of a phenol resin, a furan resin, an epoxy resin, a urethane resin, and a copolymer thereof.
The fiber-forming polymer compound is preferably at least one selected from the group consisting of cellulose diacetate, cellulose triacetate, polyacrylonitrile, polyvinyl butyral, polyvinyl acetate, polyamide, polyester, and copolymers thereof. .
The bark is preferably at least one bark selected from the group consisting of acacia, quebraco, and radiatapine.

  According to the present invention, carbon fibers and activated carbon fibers can be produced with a high yield, and in particular, activated carbon fibers having a large specific surface area and large total volume of mesopores can be produced at low cost.

<Method for producing carbon fiber>
The method for producing a carbon fiber of the present invention includes a step of producing a conjugate fiber and a step of carbonizing the produced conjugate fiber, wherein the step of producing the conjugate fiber comprises discharging a spinning stock solution from pores. It has a spinning step for solidification. In the present invention, a specific spinning solution is used in this spinning process.
Hereinafter, first, the carbon fiber production method of the present invention will be described in detail with reference to embodiments.

[First Embodiment]
(Process for producing composite fibers)
In the carbon fiber manufacturing method of this embodiment, at least one kind of bark extract composition extracted from the bark with a solvent in a spinning process in a process of manufacturing a composite fiber (hereinafter referred to as a composite fiber manufacturing process). A mixed solution containing the above fiber-forming polymer compound is used as a spinning dope.

  As the bark used when preparing the spinning dope, for example, acacia, quebraco, mangrove, eucalyptus, radiata pine, cedar, larch, cypress, hiba, oak can be used. A composite fiber is obtained, and when it is made into carbon fiber, it is easy to maintain the fiber shape, and it is easy to obtain a suitable activated carbon fiber precursor. Therefore, 1 selected from the group consisting of acacia, quebraco, and radiatapine It is preferred to use more than seed bark. In addition, the bark extract composition contains polyphenols such as flavonoids, but the content of polyphenols is high, the growth is easy to obtain quickly, the extraction rate of the resin extract composition is high, and the high fiber Acacia bark is preferably used from the standpoint of strength. Specific examples of acacia include mimosa acacia, morishima acacia, acacia mangum, acacia aurikariformis, and a hybrid of these primary species, acacia hybrid.

  When extracting the bark extraction composition from the bark, it is preferable that the bark is physically pulverized in advance with a hammer mill or the like to increase the extraction efficiency by increasing the surface area of the bark. Although there is no restriction | limiting in particular in the shape and magnitude | size of a chip | tip here, the thing made into the particle size of 5-60 mesh is preferable. More preferably, it is 30-60 mesh, More preferably, it is 50-60 mesh.

By heating the mixture in which the bark and the solvent are mixed, the solvent-soluble component in the bark is transferred to the solvent. Thereafter, the mixture is subjected to solid-liquid separation, and the solvent is removed from the obtained liquid to obtain a solid bark extract composition.
The bark extract composition thus obtained contains at least polyphenols such as flavonoids and tannins, and potassium, silicon, calcium, magnesium originally contained in the bark, depending on the type of solvent used for extraction. Some of the ash (inorganic components) such as sodium, phosphorus, sulfur, boron, manganese, barium, aluminum, iron, and zinc are also included. Further, the bark extract composition usually includes saccharides and derivatives thereof, terpenoids and the like.

Solvents used for extracting the bark extract composition from the bark include water, methanol, ethanol, hexanol, ether, acetone, cyclohexanone, benzene, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, 2-methylpyrrolidone, n- Examples include organic solvents such as hexane and cyclohexane. Of these, one kind may be used alone, or two or more kinds may be used in combination, but water, methanol, or acetone may be used from the viewpoint of handling. preferable. Furthermore, the use of methanol or acetone is also preferable in that the extraction rate of the bark extraction composition is improved as compared with the case of using water. Further, in the case of producing carbon fiber as an activated carbon fiber precursor, the use of the activated carbon fiber is particularly required to have a low ash content, such as an electrode for an electric double layer capacitor. In this case, methanol or acetone is preferably used as a solvent for extracting the bark extract composition from the bark. This is because when compared with water and methanol or acetone, the amount of ash in the bark extract composition obtained by using methanol or acetone is lower, and as a result, activated carbon fibers with a lower ash content tend to be obtained. Because it is in.
Therefore, in the present invention, methanol and / or acetone is used as the solvent.

There are no particular restrictions on the specific method of extraction or the equipment to be used, but using an extraction apparatus equipped with a reflux condenser, the mixture of bark and solvent is heated at a temperature about the boiling point of the solvent, and the solvent is removed. A method of extraction while refluxing is preferred. The extraction time is preferably 0.5 to 24 hours, more preferably 0.5 to 3 hours. Moreover, bark: solvent = 1: 2-10 are preferable as mass ratio of the bark and solvent which are mixed here. When the extraction time and mass ratio are in such ranges, effective extraction can be performed. In particular, about 1: 2 is more preferable from an industrial viewpoint and an economic aspect.
Moreover, there is no restriction | limiting in particular also in the method of carrying out solid-liquid separation of the mixture after heating in this way, What is necessary is just to carry out by filtration, centrifugation, etc. The method for removing the solvent from the liquid obtained by solid-liquid separation is not particularly limited, and a known method such as evaporation to dryness may be employed.

The bark extract composition thus obtained is added to an organic solvent together with at least one fiber-forming polymer compound to prepare a spinning dope containing them.
Then, the spinning solution is discharged from the pores and solidified (spinning step), and then the obtained spinning yarn is stretched to obtain a fibrous material (stretching step), and then the fibrous material is cured. A composite fiber can be manufactured by (curing process).

  The fiber-forming polymer compound is a polymer compound having fiber-forming ability, and fiber formation is possible by using this compound together with the bark extract composition. Examples of such fiber-forming polymer compounds include cellulose diacetate, cellulose triacetate, polyacrylonitrile, polyvinyl butyral, polyvinyl acetate, polyamide, polyester, and copolymers thereof. It is preferable to select and use. However, when cellulose diacetate is used, a composite fiber having higher strength can be efficiently obtained. Therefore, handling properties when producing carbon fiber, and further, this carbon fiber is activated carbon. Handling property when producing activated carbon fiber as a fiber precursor is excellent and efficient.

By adding such a fiber-forming polymer compound and the above-described bark extract composition to an organic solvent, a spinning dope can be prepared.
For example, when cellulose diacetate and / or cellulose triacetate is used as the fiber-forming polymer compound, when 2-methylpyrrolidone (NMP), dioxolane, methylene chloride, tetrachloromethane is used as the organic solvent, It is preferable that cellulose triacetate can be dissolved together. When cellulose diacetate is used alone, acetone, methyl ethyl ketone, cyclohexanone, diacetone alcohol, methyl formate, methyl acetate, ethyl acetate, ethyl lactate, nitromethane, dimethylformamide, methyl glycol acetate, tetrahydrofuran, dioxane, chloroform, dimethyl Sulfoxide is also preferred because it can dissolve cellulose diacetate. Of these, NMP and acetone are preferred because they are easy to handle. Moreover, an organic solvent may be used individually by 1 type, or 2 or more types may be mixed and used for it.

The mass ratio of the bark extraction composition to the fiber-forming polymer compound in the spinning dope is preferably bark extraction composition: fiber-forming polymer compound = 1: 99 to 99: 1. Within this range, it is easy to form into a fiber, and it is easy to stably carry out the spinning process, stretching process, and curing process, and it is easy to obtain a composite fiber with good strength. However, if the ratio of the fiber-forming polymer compound is more than 40% by mass, the fiber shape may not be maintained in the carbonization step, and the handling property is lowered. Is bark extract composition: fiber-forming polymer compound = 70: 30 to 95: 5.
Moreover, the spinning process can be performed more stably when the proportion of the organic solvent in the spinning dope is 20 to 50% by mass in the spinning dope. If it is less than this, voids are likely to be formed in the composite fiber, and if it is more than this, the viscosity tends to increase and gelation tends to occur, and yarn breakage occurs during spinning, which tends to reduce the efficiency of the spinning process. It is in.

There is no particular limitation on the method for obtaining a mixed solution which is a spinning stock solution by dissolving the fiber-forming polymer compound and the above-described bark extract composition in an organic solvent. For example, the organic solvent is contained in a container equipped with a reflux condenser. And a fiber-forming polymer compound, and while stirring and mixing with heating to a temperature about the boiling point of the organic solvent, a solution of the fiber-forming polymer compound is prepared, and then a bark extract composition is added thereto. And stirring with a homogenizer or the like to dissolve the bark extract composition.
In addition, other components such as a dispersant, a surfactant, a pigment, a dye, and an antistatic agent may be added to the spinning dope depending on the purpose.

Next, such a spinning stock solution is discharged from, for example, pores having a pore diameter of about 0.08 to 0.4 mm and solidified by desolvation to produce a spinning raw yarn (spinning step). In addition, the hole diameter of a pore here can be set suitably according to the target fineness. .
Specifically, the spinning dope is discharged from the pores into a gas gas phase such as air or an inert gas, and then introduced into the coagulation bath. The spinning dope is fed from the pores to the coagulation liquid. A wet spinning method that directly discharges into the inside, a dry spinning method in which a spinning solution is discharged into the gas phase and solidified can be adopted. Further, for the discharge, a spinneret (spinning nozzle) equipped with a discharge amount control device such as a gear pump may be used.

When the spinning process is performed by a dry-wet spinning method or a wet spinning method, a coagulating liquid having a solidifying ability for the fiber-forming polymer compound in the spinning stock solution is used for the coagulating bath. The type of coagulation liquid is selected according to the type of fiber-forming polymer compound.
For example, when cellulose diacetate and / or cellulose triacetate is used as the fiber-forming polymer compound, water can be suitably used as the coagulation liquid. In order to appropriately control the coagulation rate, it is also possible to add a solvent used for the spinning dope. Furthermore, in order to adjust the coagulation rate by the salting-out / dehydration effect, a technique taken by general wet spinning such as addition of inorganic salts such as ammonium sulfate and sodium sulfate can be employed.
Although there are no particular limitations on the temperature of the spinning dope, the temperature of the coagulation bath, and the immersion time in the coagulation bath, some control is required to perform spinning in a stable and stable manner. For example, the temperature of the spinning dope is preferably in the range of 0 to 60 ° C. and less than the boiling point of the solvent contained, and the temperature of the coagulation bath is preferably −15 to 30 ° C. However, since the temperature of the spinning dope and the coagulation bath has a great influence on coagulation, it is preferably determined experimentally. Further, the immersion time in the coagulation bath is affected by the discharge fiber speed, the number of discharge fibers, the size of the coagulation bath, and the like, and may be determined experimentally as appropriate.

  Moreover, the speed at which the spinning yarn is taken up from the coagulation bath is preferably 1 to 5 times, more preferably 1 to 3 times the draw ratio in the coagulation bath, depending on the discharge fiber speed of the spinning solution into the coagulation bath. To be determined. By winding at such a speed, the spinning yarn can be obtained stably.

  On the other hand, when the spinning process is performed by a dry spinning method in which the spinning stock solution is discharged into a gas phase and solidified, air or an inert gas atmosphere heated above the boiling point of the organic solvent contained in the spinning stock solution is used as the gas phase. Is usually adopted.

After such a spinning process, the obtained spinning base yarn is stretched for the purpose of making it finer, and a stretching process for obtaining a fibrous material is performed.
Specific methods of the stretching process include a wet heat method and a dry heat method.
When stretching by the wet heat method, for example, while immersing the spinning yarn in a solution (drawing bath) containing 10 to 80% by mass of the same solvent as that used in the coagulation bath or spinning solution, The film is stretched 1 to 5 times, preferably 1 to 3 times in the temperature range.
When drawing by the dry heat method, the fiber-forming polymer compound used in the spinning stock solution has a glass transition temperature (Tg) or higher and other components in the spinning stock solution (in this example, bark extraction composition) The product may be stretched 2 to 8 times, preferably 2 to 4 times in the gas phase at a temperature lower than the temperature at which the product is rapidly self-polycondensed (about 60 to 80 ° C.). If the temperature here is equal to or higher than the temperature at which the bark extract composition rapidly undergoes polycondensation, stretching itself becomes difficult.
As described above, as the stretching step, a wet method or a dry heat method may be employed, but the dry heat method requires stretching in the specific temperature range as described above, and the composition of the spinning dope In some cases, such a temperature range itself does not exist. From this point of view, it is preferable to employ a wet method. In general, since it is difficult to increase the draw ratio in the wet method, the final draw ratio is set to 1 to 5 times, preferably 1 to 3 times as described above, by repeating the drawing at 1 to 2 times. This method is also effective. In addition, when a wet method is adopted, a large amount of solvent remains in the obtained fibrous material, so that if the operation such as bobbin winding is performed without drying the solvent (desolvation), the fibrous material The solvent may ooze out on the surface of the object, and as a result, the fibrous objects may stick together. Therefore, in order to prevent this, the obtained fibrous material may be heated to remove the solvent, or may be washed with saturated steam treatment. In this case, the preferable temperature range of saturated water vapor is 90 to 98 ° C.

Since the fibrous material obtained in such a stretching process is in an uncured state of the components in the fiber, a curing process is then performed to obtain a composite fiber. By the curing step, the fibrous material becomes a composite fiber having excellent strength, and is suitable as a raw material for carbon fiber and activated carbon fiber.
As the curing step, a method of heating the fibrous material at a temperature of, for example, 80 ° C. or more is simple and preferable. However, in some cases, curing by chemical treatment using an acid-formalin mixed solution or the like may be performed. Good.
In the case where the curing step is performed by heating, the fibrous material is sufficiently dried by air drying or heating, and then heated and cured at a temperature of 80 ° C. or higher. The specific temperature at this time may be determined in consideration of the Tg of the fiber-forming polymer compound. Although the time required for hardening is about 1 to 24 hours, it depends on the performance of the heating furnace to be used, the convergence thickness of the fibrous material, the supply amount of the fibrous material in the heating furnace, and the like. In general, as the heating temperature increases, the time required for curing tends to be shortened. By such a curing step, the strength of the fibrous material is greatly improved, and a high strength composite fiber is obtained. At this time, conditions such as the temperature and time of the curing step have a correlation with the strength of the obtained composite fiber, and therefore may be determined experimentally according to the required strength. The atmosphere during heating may be air, but if necessary, it may be performed in an inert gas atmosphere.
When curing is performed using an acid-formalin solution, the fibrous material may be immersed in formalin to which an acid catalyst such as hydrochloric acid or sulfuric acid is added and heated. However, such a method is difficult to control the temperature, and the production process needs to be a batch type, and the productivity is not good. Therefore, the curing step is preferably performed by a method using heating as described above.

(Process to carbonize composite fiber)
A carbon fiber can be produced by carrying out a step of carbonizing the composite fiber thus obtained (hereinafter referred to as a carbonization step).
What is necessary is just to implement a carbonization process by a well-known method, for example, what is necessary is just to carbonize a composite fiber by heating at 400-600 degreeC for about several hours by inert atmosphere. Specifically, the carbonization time may be experimentally determined according to the carbon fiber yield and the like.
In addition, you may perform the insoluble infusible process (for example, 0.5 to 8 hours at 250-300 degreeC) which heats a composite fiber in an oxidizing atmosphere before a carbonization process. When such pretreatment is performed, when a fiber-forming polymer compound that melts by heating is employed, the melting can be suppressed, and the fiber shape is easily maintained in the carbonization step. Moreover, since the crosslink density of the composite fiber is improved by such pretreatment, high strength carbon fiber can be obtained at a higher yield after the carbonization step.

Thus, a bark extract composition obtained by heating a mixture of bark and methanol and / or acetone, followed by solid-liquid separation and removing the solvent from the resulting liquid , and at least one fiber-forming composition A composite fiber containing a molecular compound is used as a spinning stock solution to produce a composite fiber. By carbonizing the obtained composite fiber, the ratio of the composite fiber burned out during carbonization is low, and the carbon fiber is produced in a high yield. Is obtained.
Moreover, since such a method is a method of using bark that has been often discarded in the past, it is preferable from the viewpoint of effective use of waste and cost.

  In addition, such a method is also preferable in that no complicated treatment such as purification is required when the bark extract composition is used as a spinning dope. However, before using the bark extract composition in the spinning dope, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, butyric acid, lactic acid, benzenesulfonic acid, p-toluenesulfonic acid, phenolsulfonic acid , Using at least one of metal salts such as boric acid, zinc chloride and zinc acetate as an acid catalyst, and maintaining the bark extract composition at a temperature between room temperature and 120 ° C. A pretreatment for self-polycondensation of at least a part of the polyphenols contained in may be performed. When such pretreatment is performed, the monomer components in the spinning dope are reduced, so that not only the spinning stability in the spinning process is improved, but also the time required for the curing process can be shortened. Therefore, you may implement such pre-processing as needed.

[Second Embodiment]
In this embodiment, in the spinning process in the composite fiber manufacturing process, the mixed liquid used as the spinning raw solution contains a thermosetting resin in addition to the bark extract composition and the fiber-forming polymer compound. Thus, it is different from the first embodiment. As a specific method of the spinning step of spinning the spinning dope, the subsequent drawing step and the curing step, and the specific method of the carbonization step, the method described in the first embodiment can be similarly employed.
As the thermosetting resin, one or more of a resole type or novolac type phenol resin, an epoxy resin, a furan resin, a urethane resin, and a copolymer thereof can be used. The phenol resin has a skeleton similar to that of polyphenols. However, it is preferable because it tends to be uniform with the bark extract composition.

  In this way, when a mixed solution containing a thermosetting resin is further used as the spinning stock solution, since the thermosetting resin is used, the low molecular weight component in the bark extract composition in the spinning stock solution and A part of the thermosetting resin reacts to become a spinning dope containing a higher molecular weight component. As a result, the spinning stability in the spinning process is improved, and the curing process proceeds more efficiently. Further, when the carbon fiber obtained by using the thermosetting resin is an activated carbon fiber precursor, the specific surface area is compared with the case where the carbon fiber obtained in the first embodiment is an activated carbon fiber precursor. In addition, although the total volume of the mesopores is slightly low, activated carbon fibers having a reduced ash content tend to be obtained in a higher yield.

The amount of the thermosetting resin to be used is not particularly limited, but when the total amount of the bark extraction composition and the thermosetting resin is 100% by mass, the bark extraction composition is preferably 10% by mass or more. 40% by mass or more is more preferable. Within such a range, spinning stability is excellent. Further, when the amount of the thermosetting resin is increased, when the obtained carbon fiber is used as an activated carbon fiber precursor, the pore diameter of the obtained activated carbon fiber tends to be reduced, and as described above, the ratio Although the surface area and the total volume of mesopores are somewhat low, activated carbon fibers with reduced ash content tend to be obtained in higher yields. Therefore, when manufacturing the carbon fiber as an activated carbon fiber precursor, it is preferable to determine the amount of the thermosetting resin in consideration of these balances.
The amount of the fiber-forming polymer compound used in the spinning dope is preferably the sum of the bark extraction composition and the thermosetting resin: fiber-forming polymer compound = 1: 99 to 99: 1, more preferably. Is 60:40 to 95: 5, more preferably 80:20 to 90:10. Within this range, it is easy to form into a fiber shape, and it is easy to stably carry out the spinning process, stretching process, and curing process, and it is easy to obtain a composite fiber with good strength.
Further, as in the case of the first embodiment, the stretching process may adopt a wet method or a dry heat method, but in the case of this embodiment example, an attempt is made to adopt the dry heat method. Then, in determining the temperature condition, it is necessary to consider the temperature at which the thermosetting resin in the spinning dope rapidly cures (about 60 to 80 ° C.). Adoption of the method is preferred.

[Third Embodiment]
In this embodiment, when preparing the spinning dope, the bark extract composition is not used as it is together with the fiber-forming polymer compound, but a reaction product obtained by reacting the bark extract composition with another substance is used. This is different from the first embodiment. As a specific method of the spinning step of spinning the spinning dope, the subsequent drawing step and the curing step, and the specific method of the carbonization step, the method described in the first embodiment can be similarly employed.
Any other substance may be used as long as it causes an addition reaction or a condensation reaction with the polyphenols in the bark extract composition to produce a reaction product having a higher molecular weight than that of the polyphenols. And thermosetting resins. The reaction proceeds without a catalyst, but it is more preferable to use a catalyst.

When reacting aldehydes with the bark extract composition, aldehydes include formaldehyde, trioxane, furfural, paraformaldehyde, benzaldehyde, methyl hemiformal, ethyl hemiformal, propyl hemiformal, salicylaldehyde, butyl hemiformal, phenyl hemiformal, Acetaldehyde, propylaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, crotonaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p- Nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p -Methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde can be mentioned, and one or more thereof can be used. Of these, formaldehyde, paraformaldehyde, furfural, benzaldehyde, and salicylaldehyde are preferable, and formaldehyde and paraformaldehyde are particularly preferable in terms of industrial viewpoint, reactivity, and the like.
As the catalyst, in addition to the acid catalyst exemplified in the first embodiment, a base catalyst can be used. Examples of the base catalyst include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, and lithium hydroxide. Alkali metal or alkaline earth metal hydroxides and amines such as ammonium hydroxide, monoethylamine, diethylamine, triethylamine, diethanolamine, triethanolamine, ethylenediamine, triethylenediamine, hexamethylenetetramine, and the like are included. Can be used.
In the presence of these catalysts, holding the bark extract composition and aldehydes in a solvent such as methanol at a temperature between room temperature and 120 ° C. adds aldehydes to the polyphenols in the bark extract composition and further adds them. The addition product produced by the above and polyphenols are condensed. Then, by repeating such addition and condensation, a higher molecular weight reaction product is obtained.

Moreover, when making a thermosetting resin react with a bark extraction composition, as a thermosetting resin, 1 or more types of a resol type or novolak type phenol resin, an epoxy resin, a furan resin, a urethane resin, and these copolymers are used. However, a phenol resin is preferable because it has a skeleton similar to polyphenols and tends to be uniform with the bark extract composition.
As a catalyst, the acid catalyst and alkali catalyst which were illustrated when reacting aldehydes can be used similarly.
And in the presence of these catalysts, when the bark extract composition and the thermosetting resin are kept in a solvent such as methanol at room temperature to 120 ° C., the polyphenols and the thermosetting resin in the bark extract composition And a higher molecular weight reaction product is obtained.
The reaction that proceeds at this time is a condensation reaction between polyphenols contained in the bark extract composition and the phenol resin when a phenol resin is used as the thermosetting resin.

  According to the method of this example, since a reaction product is used, a spinning dope containing a higher molecular weight component than that of the first embodiment is obtained. As a result, the spinning stability in the spinning process is improved, and the curing process proceeds more efficiently. Moreover, when the carbon fiber obtained using such a reaction product is used as the activated carbon fiber precursor, compared with the case where the carbon fiber obtained in the first embodiment is used as the activated carbon fiber precursor. Although the specific surface area and the total volume of the mesopores are somewhat low, activated carbon fibers tend to be obtained in a higher yield.

The mass ratio of the bark extract composition to the aldehydes reacted therewith is not particularly limited, but from the viewpoint of spinning stability due to polymerization and reaction control, the total amount of the bark extract composition and aldehydes In 100% by mass, the bark extract composition is preferably 50% by mass or more.
In addition, there is no particular limitation on the mass ratio of the bark extract composition and the thermosetting resin to be reacted therewith, but from the viewpoint of spinning stability by polymerization and reaction control, the bark extract composition and the thermosetting resin are cured. When the total amount with the conductive resin is 100% by mass, the bark extract composition is preferably 20% by mass or more, and more preferably 40% by mass or more.
In addition, when the amount of aldehydes or thermosetting resin increases, when the obtained carbon fiber is used as an activated carbon fiber precursor, the pore diameter of the obtained activated carbon fiber tends to decrease, as described above. In addition, although the specific surface area and the total volume of the mesopores are somewhat low, activated carbon fibers tend to be obtained in a higher yield. Therefore, when manufacturing carbon fiber as an activated carbon fiber precursor, it is preferable to determine the amount of aldehydes and thermosetting resin in consideration of these balances.
The amount of the fiber-forming polymer compound used in the spinning dope is preferably reaction product: fiber-forming polymer compound = 1: 99 to 99: 1, more preferably 60:40 to 95: 5. More preferably, it is 80: 20-90: 10. Within this range, it is easy to form into a fiber shape, and it is easy to stably carry out the spinning process, stretching process, and curing process, and it is easy to obtain a composite fiber with good strength.
Further, as in the case of the first embodiment, the stretching process may adopt a wet method or a dry heat method, but in the case of this embodiment example, an attempt is made to adopt the dry heat method. Then, in determining the temperature condition, it is necessary to consider the temperature at which the reaction product in the spinning dope rapidly cures (about 60 to 80 ° C.). Is preferable.

According to the carbon fiber production methods described above, carbon fibers can be produced with high yield. The carbon fibers thus obtained are suitable for friction materials such as brakes and clutches, and ablation materials, for example. Can be used.
Depending on the purpose, a bark extract composition and a reaction product of the bark extract composition may be used in combination with a fiber-forming polymer compound, or a reaction product of the bark extract composition and a thermosetting resin may be used in combination. It is also possible to do.

Next, the manufacturing method of the activated carbon fiber of this invention is demonstrated in detail.
<Method for producing activated carbon fiber>
The method for producing activated carbon fiber of the present invention includes the step of carbonizing and activating the conjugate fiber produced in the above-described conjugate fiber production step (hereinafter referred to as “carbonization / activation step”). A method for producing fibers.
As the composite fiber production process, any of the methods exemplified in the first to third embodiments can be preferably employed in the carbon fiber production method, and in particular, as the bark extract composition, extraction of bark of acacia, quebraco, and radiatapine When the composition is used, an activated carbon fiber that maintains a good fiber shape and can be easily processed into felt, cloth, and the like can be obtained.
However, when manufacturing what is required to have a low ash content, such as an electrode for an electric double layer capacitor, for example, as an activated carbon fiber, a solvent for extracting the bark extract composition from the bark As methanol, it is preferable to use methanol or acetone. This is because when compared with water and methanol or acetone, the amount of ash in the bark extract composition obtained by using methanol or acetone is lower, and as a result, activated carbon fibers with a lower ash content tend to be obtained. Because it is in.
In addition, when cellulose diacetate is used as the fiber-forming polymer compound, a composite fiber having higher strength can be obtained efficiently, so that it is excellent in handling properties when producing activated carbon fibers and is efficient. .

The carbonization / activation process may be performed by a known method, and after carbon fiber is once produced by carbonization, the carbon fiber may be activated, or carbonization and activation may be performed in one process. The activation includes a chemical activation method using a chemical and a gas activation method using a gas, but any method may be adopted.
For example, when a chemical activation method is employed as the activation method, the composite fiber is impregnated with a chemical such as zinc chloride or phosphoric acid or an alkali such as potassium hydroxide, and is kept at 400 to 1000 ° C. for several hours in an inert atmosphere. What is necessary is just to heat about. The specific heating time may be experimentally determined according to the specific surface area required for the activated carbon fiber. According to such a method, carbonization progresses with activation, so that carbonization and activation can be performed in one step.
When a gas activation method is employed as the activation method, the composite fiber is heated and carbonized at 400 to 600 ° C. for about several hours in an inert atmosphere, and the resulting carbon fiber is activated with water vapor, carbon dioxide, or the like. What is necessary is just to react with gas and react for about tens of minutes to several hours, and to activate (gas activation). At this time, carbonization and activation may be performed continuously in the same apparatus, or may be performed independently. Specifically, the carbonization time and activation time at this time may be experimentally determined according to the activated carbon fiber yield, the specific surface area required for the activated carbon fiber, and the like.
Moreover, it is preferable to employ | adopt a gas activation method from the point from which the activated carbon fiber with little ash content is obtained when a chemical activation method and a gas activation method are compared.

By carbonizing and activating the composite fiber using the bark extract composition as a raw material in this way, it has a good fiber shape, a specific surface area of 1000 m ² / g or more and a total volume of mesopores of 0.1 ml. Activated carbon fiber having a high specific surface area of at least / g and a high total mesopore volume.
Further, according to such a method, activation tends to proceed effectively in a very short time, energy consumption required for activation can be suppressed, and this is preferable in terms of cost. Moreover, according to such a method, the burning during activation is suppressed, and activated carbon fibers can be obtained with a high yield.
It is not clear why the activated carbon fiber having a large specific surface area and large total mesopore volume can be efficiently produced by carbonizing and activating the composite fiber using the bark extract composition as a raw material. It can be inferred that this is due to the skeleton structure of the polyphenols contained in the extraction composition.

  Further, in such a method, in the production of the spinning dope for producing the composite fiber, the bark is not used as it is, but the bark extraction in which a part of the ash originally contained in the bark is separated and removed by the extraction operation. Since the composition is used, an activated carbon fiber having a low ash content can be obtained. Conventionally, if the obtained activated carbon fiber contains a large amount of ash, it cannot be used as it is for an electrode for an electric double layer capacitor or the like, and in some cases, it is necessary to remove ash at an enormous cost. there were. However, in the case of activated carbon fiber produced by carbonizing and activating a composite fiber using a bark extract composition as a raw material, such a removal treatment is not necessary.

According to the method for producing activated carbon fibers described above, activated carbon fibers having both a large specific surface area and a large total volume of mesopores and a good fiber shape can be produced at a low cost and in a high yield. The fiber can be suitably used for various applications including an adsorbent and an electrode for an electric double layer capacitor. Furthermore, according to the manufacturing method of the first embodiment in which the bark extract composition is used alone in addition to the fiber-forming polymer compound when preparing the spinning dope, the higher specific surface area and the total volume of the mesopores are obtained. According to the production method of the second and third embodiments using a mixture of bark extract composition and reaction product, activated carbon fiber with less ash content can be produced at a higher yield. It tends to be possible. Therefore, it is possible to design and manufacture activated carbon fibers according to the application and required grade as appropriate.
Depending on the purpose, a bark extract composition and a reaction product of the bark extract composition may be used in combination with a fiber-forming polymer compound, or a reaction product of the bark extract composition and a thermosetting resin may be used in combination. It is also possible to do.

Hereinafter, the present invention will be specifically described with reference to examples.
[Example 1]
Acacia bark chip: A mixture of 600 g and methanol: 1800 g is placed in a flask, heated to 65 ° C. with a mantle heater, stirred for 1 hour while maintaining the reflux state of methanol, and a bark extract composition containing polyphenols The operation for extracting was performed.
Next, the mixture was cooled to room temperature, filtered to a solid (bark) and a liquid (extract), and the obtained extract was put into a rotary evaporator. In addition, the obtained liquid was red black. Then, the pressure was maintained at 60 ° C. and methanol was evaporated (evaporation to dryness) to obtain 240 g of a solid bark extract composition.
On the other hand, 100 g of cellulose diacetate having an acetylation degree of 55% and a polymerization degree of 120 is put in 900 g of acetone and stirred at room temperature for about 1 hour, followed by stirring and mixing for 30 minutes while maintaining at 60 ° C. in a flask equipped with a reflux condenser. And completely dissolved. Thereafter, this solution was cooled to obtain a cellulose diacetate solution (solid content: 10% by mass).
Next, the above-mentioned bark extract composition is added to the cellulose diacetate solution so that the mass ratio of the solid content is bark extract composition: cellulose diacetate = 70: 30, and the mixture is stirred with a small homogenizer. A spinning stock solution, which is a reddish brown mixed solution, was prepared.
Then, the spinning solution is extruded from a spinneret having a hole diameter of 0.1 mm and a hole number of 80 while maintaining a constant discharge amount, and discharged into a coagulation bath composed of an aqueous acetone solution (acetone concentration: 10% by mass) at 25 ° C. Went. Under the present circumstances, the rotation speed of the winding roller was adjusted so that a draw ratio might be 2-3 times in a coagulation bath. The immersion time in the coagulation bath was about 60 seconds.
Next, a drawing process was performed in which the wound spinning yarn was drawn in a 50 ° C. aqueous acetone solution (acetone concentration: 10% by mass) to obtain a fibrous material. The draw ratio here was 2 times.
Thereafter, while maintaining the tension in the stretching step, the fibrous material was air-dried at room temperature for 5 minutes and further subjected to a drying heat treatment at 130 ° C. for 30 minutes to obtain a composite fiber.
The spinning process to the stretching process were performed with a continuous apparatus, and the air drying and curing processes were performed using a continuous apparatus different from the continuous apparatus.

Next, 10 g of the composite fiber obtained in this manner was collected, re-dried at 105 ° C. for 1 hour, and then placed in a carbonization furnace, and a rate of 5 ° C./minute from room temperature to 900 ° C. in a nitrogen stream. And heated at 900 ° C. for 30 minutes. Then, this was cooled and taken out to 100 degreeC in nitrogen stream, and carbon fiber was obtained.
On the other hand, 10 g of the composite fiber was separately collected and re-dried at 105 ° C. for 1 hour, and then placed in a carbonization furnace. The temperature was raised from room temperature to 900 ° C. at a rate of 5 ° C./minute in a nitrogen stream. Hold at 30 ° C. for 30 minutes. Thereafter, water vapor was mixed in the nitrogen stream (water vapor concentration: 33% by volume), and gas activation was performed for 50 minutes. Then, mixing of water vapor | steam was stopped and it cooled to 100 degreeC in nitrogen stream, and obtained the activated carbon fiber.

Table 1 shows the results of specific surface area measurement calculated using the BJH method from the nitrogen adsorption isotherm and pore distribution analysis calculated using the BJH method for the obtained activated carbon fibers. The total pore volume is the total volume of all pores formed in the activated carbon fiber, and the mesopore volume ratio is the total number of mesopores (pores having a pore diameter of 3 to 30 nm) with respect to the total pore volume. It is the volume ratio [%].
Moreover, the mass of the obtained carbon fiber with respect to the mass of the composite fiber subjected to carbonization, the mass of the obtained activated carbon fiber with respect to the mass of the composite fiber subjected to carbonization and activation, respectively, the yield of the carbon fiber, and the activated carbon fiber. The yield is shown in Table 1 as [%].
Further, 1 g of activated carbon fiber finely pulverized in an agate mortar and 50 g of 1 mol / l hydrochloric acid were mixed and stirred with a magnetic stirrer at room temperature for 24 hours. The activated carbon fiber was filtered off, and the ash content in the filtrate ( K, Si, Ca, Mg, Na, P, S, B, Mn, Ba, Al, Fe, Zn) content was quantified by ICP analysis and expressed as ash content (metal content ppm in filtrate) It was shown in 1.

[Example 2]
The reaction product of bark extraction composition and formaldehyde is used in place of the bark extraction composition, and the reaction product (diacetic acid) in mass ratio of the reaction product (solid content) in the cellulose diacetate solution. A spinning stock solution was prepared in the same manner as in Example 1 except that cellulose was added so as to be 90:10, and each step was performed in the same manner as in Example 1 to produce a composite fiber. Then, carbon fibers and activated carbon fibers were produced from the obtained composite fibers in the same manner as in Example 1, and these were evaluated in the same manner as in Example 1. The results are shown in Table 1.
The reaction product of the bark extract composition and formaldehyde was prepared as follows.
First, a bark extract composition was obtained in the same manner as in Example 1. Next, after 100 g of this bark extract composition was dissolved in 100 g of methanol in a flask, 200 g of formalin (formaldehyde 37% by mass aqueous solution) was added and mixed well. Further, 0.1 g of hydrochloric acid was added as an acid catalyst. The reaction was refluxed at 0 ° C. for 1 hour. Thereafter, the reaction is concentrated under reduced pressure of 80 mmHg until the internal temperature of the contents rises to 80 ° C., and further kept at 80 ° C. and 80 mmHg, and the reaction product of the bark extract composition (solid content 80 mass) %, Viscosity 7000 mPa · s).

[Example 3]
Instead of the bark extract composition, a mixture of the bark extract composition and the resol type phenol resin is used. In the cellulose diacetate solution, the amount of this mixture (solid content) is a mixture by mass ratio: cellulose diacetate = 90. : A spinning stock solution was prepared in the same manner as in Example 1 except that the amount was 10 so that each step was performed in the same manner as in Example 1 to produce a composite fiber. Then, carbon fibers and activated carbon fibers were produced from the obtained composite fibers in the same manner as in Example 1, and these were evaluated in the same manner as in Example 1. The results are shown in Table 1.
In addition, the mixture of a bark extraction composition and a resol type phenol resin was prepared as follows.
First, a bark extract composition was obtained in the same manner as in Example 1.
On the other hand, 400 g of phenol and 440 g of formalin (formaldehyde 50 mass% aqueous solution) were charged into a reaction vessel, 74 g of 25 mass% aqueous ammonia was added, and reacted at 60 ° C. for 3 hours. Thereafter, under reduced pressure of 80 mmHg, a dehydration concentration reaction is performed until the internal temperature of the contents in the reaction vessel rises to 80 ° C., and further maintained as it is at 80 ° C. and 80 mmHg. Type phenol resin (solid content 80 mass%) was obtained.

[Comparative Example 1]
First, a phenol resin fiber was produced as follows.
A thermoplastic novolak resin having an average molecular weight of 1200 (melt viscosity: 36 Pa · s at 150 ° C.) was melted at 180 ° C., and this was introduced into a spinning pack set at 150 ° C. through a gear pump adjusted to have a constant discharge rate. , And ejected from a spinneret of 100 holes (hole diameter 0.2 mm, capilla L / D = 3).
While the spinning yarn thus obtained was cooled with a cooling air of 20 ° C. in the quench zone, the winding speed was set to 300 m / min, and an uncured yarn having a fineness of 2.2 dtex (decitex) was obtained (direct spinning method). .
Next, the wound uncured yarn was cut off from the bobbin and cut to a length of 51 mm.
And after immersing this in 25 degreeC mixed aqueous solution of hydrochloric acid 15 mass% and formaldehyde 10 mass% and leaving still for 1 hour, it puts in the heater with a temperature controller, and heats up to 98 degreeC over 6 hours, While maintaining at 98 ° C., it was held for 10 hours to carry out a curing reaction.
Thereafter, the hardened string thread was taken out from the heater, immersed in warm water at 60 ° C. for 30 minutes, and then washed with running water for 1 hour. Next, the taken-out silk thread was immersed in 3% by mass of ammonia water maintained at 60 ° C. for 3 hours, and neutralized. Then, the neutralized yarn thread was immersed in warm water at 60 ° C. for 30 minutes, and then washed with running water for 1 hour.
Thereafter, the taken-out thread string was dried at 105 ° C. for 30 minutes to obtain a yellow phenol resin fiber.

  Then, carbon fibers and activated carbon fibers were produced from the obtained phenol resin fibers in the same manner as in Example 1, and these were evaluated in the same manner as in Example 1. The results are shown in Table 1.

As is clear from Table 1, in Example 1 using a mixed solution containing an acacia bark extract composition together with a fiber-forming polymer compound as a spinning dope, carbon fibers can be obtained in high yield, and It was possible to obtain activated carbon fibers having a very high specific surface area and total volume of mesopores in a high yield. Further, in Example 2 using a reaction product obtained by reacting formaldehyde or a phenol resin with a bark extract composition, or in Example 3 using a mixture obtained by mixing a thermosetting resin with a bark extract composition, higher yields were obtained. Carbon fiber can be obtained at a high rate, and the specific surface area and total volume of mesopores are slightly smaller than in Example 1, but activated carbon fiber with a lower ash content than in Example 1 is obtained in a higher yield. I was able to. Moreover, in each Example, the activated carbon fiber which maintained the favorable fiber shape was obtained in any case.
On the other hand, in the comparative example 1 which manufactured the carbon fiber and the activated carbon fiber from the phenol resin fiber, both the carbon fiber yield and the activated carbon fiber yield were low. Moreover, although the obtained activated carbon fiber had a certain specific surface area to some extent, the total volume of mesopores was small, and the characteristics as an activated carbon fiber were insufficient.

[Example 4]
Quebraco bark chip: A mixture of 1500 g and acetone: 4500 g is placed in a flask, heated to 56 ° C. with a mantle heater, stirred for 1 hour while maintaining the reflux state of acetone, and a bark extract composition containing polyphenols The operation for extracting was performed.
Next, the mixture was cooled to room temperature, filtered to a solid (bark) and a liquid (extract), and the obtained extract was put into a rotary evaporator. In addition, the obtained liquid was red black. Then, the reduced pressure state was maintained at 55 ° C. to evaporate acetone (evaporation to dryness) to obtain 270 g of a solid bark extract composition.
Subsequent steps are performed in the same manner as in Example 1 to obtain a composite fiber, and further, carbon fibers and activated carbon fibers are produced from the obtained composite fiber in the same manner as in Example 1. evaluated. The results are shown in Table 2.

[Example 5]
The reaction product of bark extraction composition and formaldehyde is used in place of the bark extraction composition, and the reaction product (diacetic acid) in mass ratio of the reaction product (solid content) in the cellulose diacetate solution. A composite fiber was obtained in the same manner as in Example 4 except that cellulose = 90:10 was added, and carbon fibers and activated carbon fibers were produced from the obtained composite fiber in the same manner as in Example 1. These were evaluated in the same manner as in Example 1. The results are shown in Table 2.
The reaction product of the bark extract composition and formaldehyde was prepared in the same manner as in Example 2 except that the bark extract composition from Quebraco bark obtained in Example 4 was used as the bark extract composition. A reaction product of bark extract composition and formaldehyde: 160 g was obtained.

[Example 6]
Radiatapine bark chip: 1500 g and methanol: 4500 g of a mixture are put in a flask. Thereafter, 300 g of a solid bark extract composition is obtained by the same process as in Example 1, and a composite fiber is further obtained. Carbon fibers and activated carbon fibers were produced from the composite fibers in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 3.

[Example 7]
Instead of the bark extract composition, a mixture of the bark extract composition and the resol type phenol resin is used. In the cellulose diacetate solution, the amount of this mixture (solid content) is a mixture by mass ratio: cellulose diacetate = 90. : A composite fiber was obtained in the same manner as in Example 6 except that the carbon fiber and the activated carbon fiber were produced from the obtained composite fiber in the same manner as in Example 1 except that it was added so as to be 10. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.
In addition, preparation of the mixture of a bark extraction composition and a resol type phenol resin is the same method as Example 3 except having used the bark extraction composition from the Radiata pine bark obtained in Example 6 as a bark extraction composition. I went there.

As is apparent from Tables 2 and 3, even when quebraco or radiatapine is used as the bark, the carbon fiber can be obtained in a high yield, and the activated carbon has a very high specific surface area and total mesopore volume. Fibers could be obtained with high yield. Moreover, any activated carbon fiber maintained the favorable fiber shape.

Claims (9)

In a method for producing a carbon fiber, comprising a step of producing a conjugate fiber and a step of carbonizing the produced conjugate fiber,
The step of producing the composite fiber includes a spinning step in which a spinning stock solution is discharged from the pores and solidified, and a mixture of bark and methanol and / or acetone is heated and solid-liquid separated as the spinning stock solution, and obtained. A method for producing carbon fiber, comprising using a mixed solution containing a bark extract composition obtained by removing a solvent from the obtained liquid and at least one fiber-forming polymer compound.   The method for producing carbon fiber according to claim 1, wherein the mixed solution further contains a thermosetting resin. In a method for producing a carbon fiber, comprising a step of producing a conjugate fiber and a step of carbonizing the produced conjugate fiber,
The step of producing the composite fiber includes a spinning step in which a spinning stock solution is discharged from the pores and solidified, and a mixture of bark and methanol and / or acetone is heated and solid-liquid separated as the spinning stock solution, and obtained. A method for producing carbon fiber, comprising using a mixed solution containing a reaction product of a bark extract composition obtained by removing a solvent from the obtained liquid and at least one fiber-forming polymer compound .   The method for producing carbon fiber according to claim 3, wherein the reaction product is a reaction product obtained by reacting the bark extract composition with a thermosetting resin or aldehydes.   The said thermosetting resin is 1 or more types chosen from the group which consists of a phenol resin, a furan resin, an epoxy resin, a urethane resin, and these copolymers, The manufacture of the carbon fiber of Claim 4 characterized by the above-mentioned. Method.   The fiber-forming polymer compound is at least one selected from the group consisting of cellulose diacetate, cellulose triacetate, polyacrylonitrile, polyvinyl butyral, polyvinyl acetate, polyamide, polyester, and copolymers thereof. A method for producing a carbon fiber according to any one of claims 1 to 5.   The method for producing carbon fiber according to any one of claims 1 to 6, wherein the bark is at least one bark selected from the group consisting of acacia, quebraco, and radiatapine. In a method for producing activated carbon fibers, comprising a step of producing a conjugate fiber, and a step of carbonizing and activating the produced conjugate fiber,
The step of producing the composite fiber includes a spinning step in which a spinning stock solution is discharged from the pores and solidified, and a mixture of bark and methanol and / or acetone is heated and solid-liquid separated as the spinning stock solution, and obtained. A method for producing activated carbon fiber, comprising using a mixed solution containing a bark extract composition obtained by removing a solvent from the obtained liquid and at least one fiber-forming polymer compound. In a method for producing activated carbon fibers, comprising a step of producing a conjugate fiber, and a step of carbonizing and activating the produced conjugate fiber,
The step of producing the composite fiber includes a spinning step in which a spinning stock solution is discharged from the pores and solidified, and a mixture of bark and methanol and / or acetone is heated and solid-liquid separated as the spinning stock solution, and obtained. Production of activated carbon fiber characterized by using a mixed solution containing a reaction product of a bark extract composition obtained by removing a solvent from the obtained liquid and at least one fiber-forming polymer compound Method.