KR20220094714A - Process for manufacturing high yield polyimide based activated carbon fiber and polyimide based activated carbon fiber using the same - Google Patents

Abstract

The present invention relates to a method for producing a polyimide-based activated carbon fiber at a high yield and a polyimide-based activated carbon fiber produced thereby. More specifically, the present invention relates to a method for producing, at a high yield, a polyimide-based activated carbon fiber, which has a large specific surface area and excellent adsorption ability of organic contaminants, through carbonization and activation processes in which a polyimide fiber is used as a precursor.

Description

Method for manufacturing high-yield polyimide-based activated carbon fiber and polyimide-based activated carbon fiber prepared therefrom { Process for manufacturing high yield polyimide based activated carbon fiber and polyimide based activated carbon fiber using the same }

The present invention relates to a method for producing activated carbon fibers using polyimide fibers as a precursor, and to activated carbon fibers produced therefrom, which have much better adsorption performance than conventional granular and powdered activated carbon, and also have an activation yield of 40% It relates to a method for producing a polyimide-based activated carbon fiber having a high yield as above, and to a polyimide-based activated carbon fiber produced therefrom.

Activated carbon is one of the porous carbon materials and is a representative adsorbent that uses a large number of micropores to adsorb and remove substances harmful to the human body. Activated carbon is used differently depending on the size of the pores, and activated carbon with relatively large mesopores is used for advanced water purification in water purification plants and as an adsorption filter in household water purifiers, and has relatively small micropores. ) developed activated carbon is used as an adsorbent to remove pollutants in the air.

Activated carbon fiber (ACF) is an activated carbon manufactured in the form of fibers to improve the adsorption performance of activated carbon. Compared to general activated carbon, the ratio of micropores is very high, so it has excellent properties in removing harmful gases. have

On the other hand, the adsorption properties of activated carbon largely depend on the micropores formed in the fibers, and are largely classified into micropores and mesopores. In particular, the microporosity is 80% It has excellent adsorption properties when it is maintained above. However, conventional activated carbon has a problem in that it cannot maintain uniform micropores. Therefore, in order to solve the problems of the conventional activated carbon, as interest in activated carbon fibers having micropores formed in thin fibers has recently increased, activated carbon fibers, which are new adsorption materials with excellent adsorption capacity, convenient to use, and excellent in reproducibility, have been developed. is attracting attention

Activated carbon fibers are generally manufactured by carbonizing and activating fibrous raw materials, and as raw materials, cellulose-based, polyvinyl alcohol-based, polyacrylonitrile-based, phenolic resin-based, pitch-based and the like are known.

Looking at the prior art related to these activated carbon fibers, Korean Patent Publication No. 0139559 (Mar. 04. 1998) discloses a certain ratio of two or more fibers among vegetable fibers, rayon cellulose, phenolic resin fibers, nylon and polyacrylonitrile. Activated carbonized fiber and non-woven fabric obtained through processes such as carbonization and activation of fibers or non-woven fabrics processed by mixing with Disclosed is an activated carbon fiber produced by unwinding waste clothing with an acrylic content of 80% or more in the form of cotton, manufacturing a nonwoven fabric, oxidizing it in an oven, and then carbonizing and activating it in a high-temperature furnace.

However, the yield of activated carbon fibers according to the prior art can be slightly changed by carrier gas or water vapor, but cellulosic and phenolic fibers such as viscose rayon and cotton show a low yield of 20%.

In addition, most activated carbon fibers according to the prior art are manufactured in the form of short fibers and are processed in the form of paper, fabric, or felt, but all activated carbon fibers made of the short fiber type material have limitations in their durability.

An object of the present invention is to provide a method for producing a polyimide-based activated carbon fiber with a high yield of 40% or more and improved durability, and a polyimide-based activated carbon fiber prepared therefrom.

The method for producing a high yield polyimide-based activated carbon fiber of the present invention for solving the above problems includes: i) a first step of wet spinning by dissolving polyamic acid in a solvent (S10); and, ii) wet-spun polya A second step (S20) of preparing a polyimide precursor fiber by imidizing the mixed acid fiber; and iii) a third step (S30) of carbonizing the polyimide precursor fiber; and iv) a fourth step (S40) of activating the carbonized polyimide precursor fiber to produce an activated carbon fiber, wherein the polyimide-based activated carbon fiber has a yield of 40% by weight compared to the polyimide precursor fiber above, the third step is performed in a nitrogen atmosphere at 800 to 1,200 °C for 1 to 60 minutes, and the fourth step is preferably performed in a nitrogen atmosphere at 800 to 1,200 °C for 1 to 60 minutes.

In addition, the fourth step is performed in a vapor or carbon dioxide atmosphere, and may include a step of treating an activator before the fourth step, wherein the activator is potassium hydroxide, sodium carbonate, sodium hydroxide, zinc chloride, chloride It is at least one selected from the group consisting of magnesium, phosphoric acid, and calcium chloride, and the treatment amount of the activator is preferably 0.5 to 5.5 wt% based on the polyimide fiber.

In particular, the polyimide-based activated carbon fiber according to the present invention has a specific surface area of 1,000 m 2 /g or more, a micropore size of 1 to 20 Å, a mesopore size of 20 to 500 Å, and a microporosity of 80% or more. have characteristics.

Activated carbon fiber according to the present invention has well-developed micropores, particularly microporosity of 90% or more, and large pores are evenly distributed on the surface. , or odor removal products, catalysts, catalyst carriers, bio-reactors, automobile air purification filters, oil filters, etc. have an effect that can be widely applied. In particular, it has a high yield of 40% by weight or more, and has the effect that it can be manufactured in various forms such as yarn, woven fabric, knitted fabric, and non-woven fabric by being made of long fibers.

1 is a manufacturing process diagram of a high-yield polyimide-based activated carbon fiber according to the present invention;
2 is a schematic diagram of a wet spinning apparatus according to the present invention,
3 is a photograph of a surface (a) and a cross-section (b) of a polyimide-based activated carbon fiber having a high yield according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms. It is provided to fully inform In addition, in the drawings for convenience of description, the size of the components may be exaggerated or reduced. In the drawings, variations of the illustrated shape can be envisaged, for example depending on manufacturing technology and/or tolerances. Accordingly, embodiments of the spirit of the present invention should not be construed as limited to the specific shape of the region shown in the present specification, but should include, for example, changes in shape caused by manufacturing.

A method for producing a polyimide-based activated carbon fiber having a high yield according to the present invention includes: i) a first step (S10) of wet spinning by dissolving polyamic acid in a solvent; ii) a second step of preparing polyimide precursor fibers by imidizing the wet-spun polyamic acid fibers (S20); iii) a third step of carbonizing the polyimide precursor fiber (S30); and iv) a fourth step (S40) of activating the carbonized polyimide precursor fiber to produce an activated carbon fiber.

In general, polyimide is produced by imidization after condensation polymerization of aromatic tetracarboxylic acid or a derivative thereof and aromatic diamine or aromatic diisocyanate.

The polyimide resin as described above is an infusible, insoluble, ultra-high heat-resistance resin, has excellent heat oxidation resistance, a long-term use temperature of about 260 ° C, and a short-term use temperature of about 480 ° C. It has very high heat resistance properties. In addition, it has excellent electrochemical and mechanical properties, radiation resistance, flame retardancy, chemical resistance, and the like.

In addition, the imidized polyimide has an oxygen functional group and an aromatic imide ring in the main chain, and has a wide structural range per molecular unit and excellent orientation.

The polyimide as described above may have various molecular structures depending on the type of monomer used. In general, PMDA (pyrometllitic dianhydride), BTDA (benzophenon tetracarboxylic dianhydride) or BPDA (biphthalic anhydride) is used as an aromatic tetracarboxylic acid component, and ODA (oxydianiline) or p-PDA (p-phenylene diamine) is used as an aromatic diamine component. ), etc. to prepare a polyamic acid by polymerization and imidize it to prepare a polyimide.

In the present invention, aromatic tetracarboxylic acid, its derivative, and aromatic diamine for producing polyamic acid as a precursor for producing a high-yield polyimide-based activated carbon fiber are not particularly limited.

In order to prepare the polyimide-based activated carbon fiber of the present invention, as shown in FIG. 1, polyamic acid is wet-spun and imidized to prepare a polyimide precursor fiber first.

The content of aromatic tetracarboxylic acid, its derivatives, and aromatic diamine in the preparation of the polyamic acid used in the preparation of the polyimide-based activated carbon fiber according to the present invention is not particularly limited. However, the polyamic acid is one selected from the group consisting of dimethylacetamide (Dimethylacetamide, DMAc), N-methyl-2-pyrrolidone (N-Methyl-2-pyrrolidone, NMP) or dimethylformamide (Dimethylformamide, DMF) By dissolving using the above solvent, a spinning dope (dope, 10) is prepared.

According to the present invention, the solvent in the preparation of the spinning dope 10 for the first step (S10) of wet spinning by dissolving the polyamic acid is particularly preferably dimethylacetamide.

At this time, it is preferable that the viscosity of the spinning dope 10 prepared by dissolving the polyamic acid in a solvent is 10,000 to 400,000 cps.

To this end, the mixing ratio of the polyamic acid and the solvent is preferably 15 to 30: 70 to 85% by weight in the preparation of the spinning dope 10 . If the mixing ratio of the polyamic acid is less than 15% by weight in the preparation of the spinning dope 10, the viscosity is too low, so that the spinning of the fiber is poor. In addition, when the mixing ratio of the polyamic acid exceeds 30% by weight, the viscosity may be high, which may be unsuitable for spinning.

The spinning dope 10 is prepared by adding polyamic acid to a solvent and then dissolving it for 2 hours while gradually raising the temperature to 80°C. The spinning dope 10 is prepared by solution polymerization of 4,4-oxydianiline and pyromellitic dianhydride as a monomer at 0 to 60° C. using dimethylacetamide as a solvent, followed by defoaming and filtration.

In this case, the spinning dope 10 in which polyamic acid, a precursor of polyimide, is dissolved in a solvent, as described above, preferably has a viscosity in the range of 10,000) to 400,000 cps by appropriately adjusting the content of the solvent. In the case of having the same viscosity as described above, it is possible to prevent a decrease in spinnability such as yarn trimming in the spinning process of the first step ( S10 ) and increase the spinning speed.

The spinning dope 10 prepared as described above can produce fibers by a dry spinning process of evaporating the solvent during spinning and a wet spinning process of extracting the solvent.

In general, solution spinning is a process used for spinning a polymer material that is difficult to melt by heat, and is divided into wet spinning and dry spinning.

The difference between the dry spinning process and the wet spinning process is that the process of dissolving a polymer material in a solvent to prepare a spinning dope is the same, but the wet spinning process is a process in which the spinning dope is directly discharged from the spinneret into the coagulation bath to solidify/solidify. In the dry spinning process, the spinning solution is discharged in hot air without a coagulation bath, and the solvent is evaporated to solidify.

In the present invention, it is preferable to wet-spun the spinning dope 10 . In the case of the wet spinning, excellent product production is possible in terms of physical properties, and the solvent can be washed in a coagulation bath, so that the solvent can be easily recovered.

2 is a schematic diagram of a wet spinning apparatus, which is an apparatus for manufacturing polyamic acid fibers 100 according to the present invention.

In the present invention, the polyamic acid fiber 100 is manufactured by spinning the spinning dope 10 in a coagulation bath 50 using a wet spinning apparatus as shown in FIG. 2 .

That is, referring to FIG. 2 , the wet spinning apparatus for manufacturing the polyamic acid fiber 100 according to the present invention includes a gear pump 15 for supplying the spinning dope 10 at a constant pressure, and the gear pump 15 . A spinneret 20 for spinning the spinneret 10 supplied from the spinneret in the form of fibers, and a coagulation bath 50 for coagulating the polyamic acid fiber bundle 40 in an unsolidified state discharged from the spinneret 20 to provide

Although the coagulation solution 30 provided in the coagulation bath 50 is a non-solvent, it is compatible with the organic solvent used in the manufacture of the spinning dope 10 . A solvent that does not dissolve the polymer and can solidify the polymer can be used without limitation. As the non-solvent, water may be used, and preferably, a mixture of water and an organic solvent may be used.

When a mixture of a non-solvent and an organic solvent is used as the coagulating solution 30, the content of the organic solvent is preferably maintained uniformly at 10 to 60 wt%.

In addition, the temperature of the coagulation liquid 30 in the coagulation bath 50 is preferably adjusted in the range of 10 to 50 ℃. When the temperature of the coagulating solution 30 is out of the above range, the spinning dope 10 is not smoothly spun, so that the efficiency of the spinning process is lowered, and the solvent may not be properly removed.

As shown in FIG. 2 , the polyamic acid fiber bundle 40 that has passed through the coagulation bath 50 removes the solvent contained in the fiber bundle 40 and the like by using water in the washing device 60 after that. do. Subsequently, the polyamic acid fiber bundle 40 that has passed through the water washing device 60 is dried in a drying device 70 and then wound up, thereby manufacturing the polyamic acid fiber 100 of the present invention.

In this case, the orifice formed in the spinneret 20 is preferably circular.

In addition, in the present invention, for smooth spinning operability, the spinning dope 10 is extruded through the spinneret 20 under a pressure of 15 to 400 psi during wet spinning, thereby preventing phenomena such as yarn breakage in the polyamic acid fiber bundle 40 . By preventing it, the radioactivity can be improved.

As described above, the polyamic acid fiber 100 produced through wet spinning is converted into polyimide precursor fibers by imidizing the polyamic acid fiber 100 through heat treatment as a second step (S20).

The heat treatment conditions during the imidization may proceed for 30 to 80 minutes at a temperature of 200 ~ 400 ℃ the polyamic acid fiber 100 .

That is, by the heat treatment process as described above, the polyamic acid fiber 100 is imidized and converted into a polyimide precursor fiber.

According to the present invention, the polyimide precursor fiber preferably has a single yarn fineness of 0.5 to 10 denier, and a total fineness of 25 to 100,000 denier.

That is, if the single yarn fineness of the polyimide precursor fiber according to the present invention is less than 0.5 denier, cutting may occur during the carbonization process, and if it exceeds 10 denier, the quality may be non-uniform and thermal stabilization may be non-uniform during the activation process. have. Therefore, the polyimide precursor fiber according to the present invention preferably has a single yarn fineness of 0.5 to 10 denier.

The polyimide precursor fiber prepared as described above is then subjected to a third step (S30), a carbonization step, and a fourth step (S40), an activation step, to produce an activated carbon fiber.

Briefly looking at the carbonization step and the activation step, by applying heat to the polyimide precursor fiber, thermal decomposition is performed under a high temperature condition to carbonize and activate the polyimide precursor fiber.

At this time, as a method of applying heat to the polyimide precursor fiber, there is a method of applying heat to the pyrolysis furnace from the outside to perform carbonization and activation, and other heating methods include a microwave heating method or a microwave plasma heating method.

The microwave heating can improve energy efficiency by directly heating the target material, but the efficiency is variable by the microwave absorbing capacity of the fiber, and the dielectric loss tangent is small. The material has the disadvantage of being difficult to heat.

Another method, microwave plasma heating, is an area heating by radiation from plasma that can be generated in a short time, and has the advantage that it is not affected by the dielectric properties of the internal material. However, a device that converts microwaves into plasma is required, and since the inside of the target material is not heated, when heating a material with low thermal conductivity and high thermal expansion coefficient, cracks occur in the material due to a large temperature gradient inside and outside the material There is this.

The carbonization step, which is the third step (S30) in the present invention, is a process of heat treatment in a nitrogen atmosphere, and in the present invention, it is preferable to proceed at 800 to 1.200 ° C., and the carbonization time is most preferably performed for 1 to 60 minutes.

The carbonization step refers to a process in which decomposition such as dehydration and deoxidation occurs when the organic raw material is heated, the oxygen bond is broken, oxygen is released in the form of water, carbon monoxide, or carbon dioxide, and volatiles are almost removed.

According to the present invention, the activation step, which is the fourth step (S40), activates the polyimide precursor fiber that has undergone the third step (S30), which is the carbonization step, in a vapor or carbon dioxide atmosphere to produce an activated carbon fiber. points to

According to the present invention, the activation step is preferably performed for 1 to 60 minutes using steam or carbon dioxide at 800 to 1,200 °C in a nitrogen atmosphere.

In the activation step (S60), the activation temperature is preferably 800 to 1,200 °C. When the activation temperature is less than 800 °C, the pore structure and specific surface area formed on the carbon fiber surface during the activation process are not well developed, and therefore, it is not preferable because it does not have sufficient adsorption performance as an adsorbent.

In addition, when the activation temperature exceeds 1,200 ° C., it is not preferable because the pore structure formed on the surface of the activated carbon fiber is destroyed due to high-temperature activation or the surface structure of the activated carbon fiber is changed, so that the adsorption performance is relatively reduced.

The activation time in the activation step (S60) according to the present invention is preferably 10 (1) to 60 minutes. When the activation time is less than 1 minute, the pore structure and specific surface area formed on the carbon fiber surface during the activation process are not well developed, and therefore, it is not preferable because it does not have sufficient adsorption performance as an adsorbent.

In addition, when the activation time exceeds 60 minutes, it is not preferable because the pore structure formed on the surface of the activated carbon fiber is destroyed due to high-temperature activation or the surface structure of the activated carbon fiber is changed, so that the adsorption performance is relatively reduced.

According to the present invention, the activation step refers to the step of developing a micropore structure by eroding the surface of the carbide by the oxidation reaction of carbon occurring in the temperature range of 800 ~ 1,200 ℃,

That is, when the carbon fiber that has undergone the carbonization step is activated with an oxidizing gas, the carbon in the most unstable position of the carbon fiber crystal is oxidized to carbon monoxide and carbon dioxide and desorbed, or a carboxyl group (-COOH), carbonyl group (=C= O) to form a functional compound. At this time, pores are formed at the sites that are desorbed through oxidation, and thus have a high specific surface area.

In general, the activation step is divided into a gas activation method using an oxidizing gas such as water vapor, carbon dioxide, or air, and a chemical activation method using various dehydrating inorganic and organic activators.

According to the present invention, the activation step may be performed using an oxidizing gas such as water vapor or carbon dioxide, and any method of performing activation by treating an activator prior to the activation step (S40) may be applied.

That is, according to the present invention, in the fourth step, the activation step may be performed by introducing the polyimide precursor fiber into a heat treatment furnace in a steam or carbon dioxide atmosphere.

Also, according to the present invention, it may include the step of treating the polyimide precursor fiber with an activating agent before the activating step (S40), wherein the activating agent is potassium hydroxide, sodium carbonate, sodium hydroxide, zinc chloride, chloride It is preferable that at least one selected from the group consisting of magnesium, phosphoric acid and calcium chloride.

That is, an aqueous solution of an activator prepared by dissolving an activator such as potassium hydroxide in distilled water is uniformly applied to the polyimide precursor fiber, and then heated in a nitrogen atmosphere through the fourth step to dehydrate and oxidize the activator. The reaction proceeds to activate the polyimide precursor fiber.

According to the present invention, it is particularly preferred that the treatment amount of the activator is 2.5 to 5.5 wt% based on the polyimide precursor fiber. That is, when the activator is less than 2.5% by weight compared to the polyimide fiber, the activation reaction rate is too low regardless of the type of the activator, the specific surface area is small and the formation of mesopores is poor.

In addition, when the activator exceeds 5.5 wt% compared to the polyimide fiber, the activation reaction rate is too high, and the activation yield is lowered.

When the carbonization step and the activation step are completed as described above, the polyimide-based activated carbon fiber of the present invention as shown in FIG. 3 is completed.

According to the present invention, since the activated carbon fiber produced through the activation step is manufactured in the form of a long fiber, it is possible to manufacture it into a woven fabric, a knitted fabric, a nonwoven fabric, and the like.

In addition, the polyimide-based activated carbon fiber according to the present invention has a weight of about 40% or more based on the weight of the polyimide precursor fiber, and thus the yield is 40% by weight or more.

The polyimide-based activated carbon fiber according to the present invention prepared as described above has a very excellent specific surface area of 1,000 m 2 /g or more, a micropore size of 1 to 20 Å, and a mesopore size of 20 to 500 Å, and thus has excellent adsorption properties. Therefore, it is possible to collect chemical and biogas gas, and it is washable, so handling is very good.

In particular, the polyimide-based activated carbon fiber according to the present invention has excellent adsorption properties with a microporosity of 85% or more, and can be manufactured into yarn, fabric, knitted fabric or non-woven fabric, and thus can be washed and has a small volume and light weight. It is possible to manufacture products in the form of

Hereinafter, the present invention will be described in more detail through examples. However, the present invention is not limited only to the following examples.

<Example 1>

Polyamic acid was polymerized using the monomers 4,4-oxydianiline and pyromellitic dianhydride and the solvent DMAc, defoamed and filtered to prepare a spinning dope, and wet spinning to prepare polyamic acid long fibers. A polyimide precursor fiber was prepared by imidizing the polyamic acid long fiber, and the single yarn fineness of the polyimide precursor fiber was 1.5 denier, the number of filaments was 3,000, and the total fineness was 4,500 denier. The polyimide precursor fiber was put into a heat treatment furnace, and carbonization was performed for 10 minutes at 800° C. in a nitrogen atmosphere. Thereafter, activated carbon fibers in the form of long fibers were prepared by activation at a temperature of 800° C. for 10 minutes in a steam atmosphere.

<Example 2>

The polyimide precursor fiber prepared under the same conditions as in Example 1 was put into a heat treatment furnace, and carbonization was performed for 10 minutes at a temperature of 1,000° C. in a nitrogen atmosphere. Thereafter, activated carbon fibers in the form of long fibers were prepared by activating them for 10 minutes at a temperature of 1,000 °C in an atmosphere in a water vapor atmosphere.

<Example 3>

The polyimide precursor fiber prepared under the same conditions as in Example 1 was put into a heat treatment furnace, and carbonization was performed for 10 minutes at a temperature of 1,000° C. in a nitrogen atmosphere. Thereafter, activated carbon fibers in the form of long fibers were prepared by activation at a temperature of 1,000° C. for 30 minutes in a water vapor atmosphere.

<Example 4>

The polyimide precursor fiber prepared under the same conditions as in Example 1 was put into a heat treatment furnace, and carbonization was performed for 10 minutes at a temperature of 1,000° C. in a nitrogen atmosphere. Thereafter, activated carbon fibers in the form of long fibers were prepared by activation at a temperature of 1,000° C. for 60 minutes in a water vapor atmosphere.

<Example 5>

The polyimide precursor fiber prepared under the same conditions as in Example 1 was put into a heat treatment furnace, and carbonization was performed for 10 minutes at a temperature of 1,000° C. in a nitrogen atmosphere. Thereafter, activated carbon fibers in the form of long fibers were prepared by activation for 10 minutes at a temperature of 1,000 °C in a carbon dioxide atmosphere.

<Example 6>

The polyimide precursor fiber prepared under the same conditions as in Example 1 was put into a heat treatment furnace, and carbonization was performed for 10 minutes at a temperature of 1,000° C. in a nitrogen atmosphere. Thereafter, the carbonized polyimide precursor fiber was treated with an aqueous solution of potassium hydroxide as an activator in an amount of 2.5 wt% based on the weight of the polyimide precursor fiber. As described above, the polyimide precursor fibers treated in an aqueous solution of potassium hydroxide as an activator were activated in a nitrogen atmosphere at a temperature of 1,000° C. for 10 minutes in heat treatment to prepare activated carbon fibers in the form of long fibers.

<Example 7>

The polyimide precursor fiber prepared under the same conditions as in Example 1 was put into a heat treatment furnace, and carbonization was performed for 10 minutes at a temperature of 1,000° C. in a nitrogen atmosphere. Thereafter, the carbonized polyimide precursor fiber was treated with an aqueous solution of magnesium chloride as an activator in an amount of 2.5 wt% based on the weight of the polyimide precursor fiber. As described above, the polyimide precursor fibers treated in an aqueous solution of magnesium chloride as an activator were activated in a nitrogen atmosphere at a temperature of 1,000° C. for 10 minutes in heat treatment to prepare activated carbon fibers in the form of long fibers.

<Example 8>

Polyamic acid was polymerized using the monomers 4,4-oxydianiline and pyromellitic dianhydride and the solvent DMAc, defoamed and filtered to prepare a spinning dope, and wet spinning to prepare polyamic acid long fibers. A polyimide precursor fiber was prepared by imidizing the polyamic acid long fiber, and the single yarn fineness of the polyimide precursor fiber was 3.0 denier, the number of filaments was 3,000, and the total fineness was 9,000 denier. The polyimide precursor fiber was put into a heat treatment furnace, and carbonization was performed for 10 minutes at a temperature of 1,000° C. in a nitrogen atmosphere. Thereafter, activated carbon fibers in the form of long fibers were prepared by activation at a temperature of 1,000 °C in a steam atmosphere for 10 minutes.

<Example 9>

The polyimide precursor fiber prepared under the same conditions as in Example 1 was cut through a chopping process, and then needle punched to prepare a nonwoven fabric. Thereafter, the non-woven polyimide precursor fiber was carbonized at 1,000° C. for 30 minutes, and then activated at a temperature of 1,000° C. in a steam atmosphere for 10 minutes to prepare a non-woven activated carbon fiber.

<Example 10>

A polyimide precursor fiber prepared under the same conditions as in Example 1 was prepared in the form of a plain weave fabric through a weaving process. Thereafter, the polyimide precursor fiber in the form of a fabric was carbonized at 1,000° C. for 10 minutes, and then activated in a steam atmosphere at a temperature of 1,000° C. for 10 minutes to prepare activated carbon fibers in the form of a fabric.

And with respect to the test pieces of <Examples 1 to 10>, the yield, tensile strength, specific surface area, and microporosity were evaluated in the following manner.

1) Yield analysis

In the preparation of the activated carbon fibers prepared in Examples 1 to 10, the weights of the polyimide precursor fibers and the prepared activated carbon fibers were measured to calculate the yield (%), and the results are shown in Table 1 below.

2) Tensile strength

Tensile strength was measured according to ASTM D3822 (Standard Test Method for Tensile Properties of Single Textile Fibers) for Examples 1 to 8 prepared in the form of long fibers among the activated carbon fibers prepared in Examples 1 to 10, and the The results are shown in Table 1.

3) Specific surface area and microporosity

The specific surface area (m ² /g) and microporosity of the activated carbon fibers prepared in Examples 1 to 4 were evaluated using a nitrogen adsorption isotherm, and the results are shown in Table 1.

Yield (wt%) Tensile strength (g/d) Specific surface area (m ² /g) Microporosity (%) Example 1 49.0 7.2 1,045 90 Example 2 48.0 6.2 1,350 91 Example 3 44.0 5.4 2,700 88 Example 4 41.0 5.1 6,300 86 Example 5 48.0 6.4 1,105 88 Example 6 42.0 5.3 1,050 90 Example 7 43.0 5.6 1,020 90 Example 8 41.5 5.2 1,132 87 Example 9 47.0 - 1,250 90 Example 10 46.0 - 1,320 91

As shown in Table 1, the yield in the production of the activated carbon fiber according to the present invention was the highest in Examples 2 and 5, and showed 48.0 wt%. In addition, Example 8 showed the lowest yield of 41.5 wt%. From the result of this yield analysis, it can be confirmed that the yield of the activated carbon fiber according to the present invention can be prepared at 40 wt% or more compared to the polyimide precursor fiber.

In addition, as shown in Table 1, it can be seen that the polyimide-based activated carbon fiber according to the present invention has a tensile strength of 5.0 g/d or more, and 1,000 m ² /g or more in all of the test pieces of Examples 1 to 10. It can be seen that it has a specific surface area. In particular, in the case of Example 4, it was confirmed that the specific surface area was very high as 6,300 m ² /g.

And it can be seen that the polyimide-based activated carbon fiber according to the present invention exhibits a measurement value of 86% or more in all of the microporosity (%) in Examples 1 to 10. That is, as shown in (b) of FIG. 3, the polyimide-based activated carbon fiber according to the present invention has large pores evenly distributed on the surface, confirming that micro pores are well developed. Therefore, it has a very high specific surface area and has excellent adsorption properties.

In addition, it can be seen from Examples 2 to 4 that when the activation time is increased, the specific surface area is increased, but the tensile strength and the yield are somewhat decreased.

As described above, according to the method for producing activated carbon fiber according to the present invention, it is possible to manufacture activated carbon fiber having well-developed micropores, particularly micropores, and excellent adsorption properties due to its high specific surface area. In particular, it has a high yield of 40% by weight or more, and has the effect that it is possible to manufacture products having various shapes and uses by being made of long fibers.

Although the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

10: radiation dope
15: gear pump
20: spinneret
40: polyamic acid fiber bundle
50: coagulation bath

Claims (6)

i) a first step of wet spinning by dissolving polyamic acid in a solvent (S10);
ii) a second step of preparing polyimide precursor fibers by imidizing the wet-spun polyamic acid fibers (S20);
iii) a third step of carbonizing the polyimide precursor fiber (S30); and
iv) a fourth step (S40) of activating the carbonized polyimide precursor fiber to produce an activated carbon fiber;
The method according to claim 1,
The third step is a method of producing a high yield polyimide-based activated carbon fiber, characterized in that it is performed for 1 to 60 minutes at 800 ~ 1,200 ℃ in a nitrogen atmosphere.
The method according to claim 1,
The fourth step is a method for producing a high yield polyimide-based activated carbon fiber, characterized in that performed for 1 to 60 minutes at 800 ~ 1,200 ℃ in a nitrogen atmosphere.
The method according to claim 1,
The fourth step is a method for producing a high yield polyimide-based activated carbon fiber, characterized in that it is carried out in a vapor or carbon dioxide atmosphere.
The method according to claim 1,
It may include a step of treating an activator before the fourth step, wherein the activator is at least one selected from the group consisting of potassium hydroxide, sodium carbonate, sodium hydroxide, zinc chloride, magnesium chloride, phosphoric acid and calcium chloride. A method for producing high-yield polyimide-based activated carbon fibers.
A high-yield polyimide-based activated carbon fiber produced by the method of any one of claims 1 to 5.

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