KR20000038842A - Method for preparing active carbon fiber having strong binding ability of coating layer and good adsorption ability - Google Patents

Abstract

PURPOSE: A method for preparing active carbon fiber used for purification of water and exhaust gas is provided to save investments and costs by using inexpensive glass fiber and to improve binding ability of coating layer and adsorption ability. CONSTITUTION: A method for preparing active carbon fiber having strong binding ability of coating layer and good adsorption ability comprises the following steps: a) mixing pitch with an organic solvent, stirring and then extracting soluble components; b) adding a thermosetting resin to the extract and mixing them; c) coating the mixture on a glass fiber and volatilizing the organic solvent; d) heat-treating the coated glass fiber from which the organic solvent is removed at temperature 500-1000°C under inert atmosphere to carbonize the coating layer; and e) activating the glass fiber wherein the coating layer is carbonized at temperature 700-1000°C under water steam.

Description

Manufacturing method of activated carbon fiber with strong adhesion of coating layer and excellent adsorption capacity

The present invention relates to a method for producing activated carbon fibers used as an adsorbent, and more particularly, by coating a pitch and a thermosetting resin on a surface of an inexpensive glass fiber, carbonizing and activating a coating layer of activated carbon fibers having excellent adhesion and adsorption capacity. It relates to a manufacturing method.

Generally, activated carbon fibers and activated carbon are used as an adsorbent for the purification of water quality and exhaust gas. Activated carbon fibers are fibrous in shape and are usually produced by activating carbon fibers. Activated carbon is formed in the order of macropores, mesopores, and micropores as the pore distribution enters the surface from the inside, so that the adsorption and desorption rate is slow, and the micropore portion that actually affects the adsorption performance is limited. On the other hand, activated carbon fiber has the advantage that the speed of adsorption and desorption is faster and the specific surface area is larger because the micropores are exposed on the surface.

Conventional activated carbon fibers are prepared by activating pitch-based, polyacrylonitrile-based, phenol-based, and cellulose-based carbon fibers in an appropriate manner, for example, Japanese Patent Application Laid-Open No. 49-116332, US Patent 4285831. And Japanese Patent Application Laid-Open No. 55-71614, Japanese Patent Application Laid-Open No. 4-126826, Japanese Patent Application Laid-Open No. 60-25528, and the like.

As such, the conventional method of activating and manufacturing carbon fibers has a high production cost of activated carbon fibers due to the high cost of carbon fibers as raw materials, and thus, there is a limit to using them universally. In addition, when the carbon fiber is activated, pores are formed in the carbon fiber itself, so mechanical properties such as strength and abrasion resistance are degraded, which makes it difficult to handle and various studies have been conducted to improve this.

As part of this research, the present inventor has proposed a method for producing activated carbon fibers having excellent mechanical properties by coating pitch on glass fibers which are cheaper than carbon fibers, and carbonizing and activating only the coating layer of the pitch (Korean Patent Application No. 97-72400). ). Although the proposed activated carbon fiber has an advantage that it can be universally applied due to its low price and excellent mechanical properties, there is a problem that the adhesion between the coating layer and the glass fiber is rather weak.

The present invention has been made in order to solve the above problems of the prior art, by coating a pitch and a thermosetting resin on the glass fiber to improve the adhesion of the coating layer and further to increase the specific surface area to improve the adsorption capacity, an object thereof.

Activated carbon fiber production method of the present invention for achieving the above object,

Mixing and stirring the pitch and the organic solvent to extract the soluble component;

Adding and mixing the thermosetting resin to the extract;

Coating the mixture on glass fibers and drying to volatilize an organic solvent;

Carbonizing the coating layer by heat-treating the coated glass fiber from which the organic solvent was removed at an inert atmosphere at a temperature of 500-1000 ° C .; And

The coating layer is carbonized glass fiber at the temperature of 700-1000 ℃ activating treatment with a steam atmosphere; is configured to include.

Hereinafter, the present invention will be described in detail.

The pitch used in the present invention can be either coal or petroleum, and is preferably used in powder form so as to be easily mixed with the organic solvent. If the pitch is melted by heating without dissolving it in an organic solvent, the viscosity is so high that it is difficult to uniformly coat the glass fiber. In addition, when the pitch is dissolved in the organic solvent, the viscosity can be lowered, the organic solvent can be easily removed by drying, and the coating thickness can be adjusted according to the pitch concentration in the organic solvent.

The organic solvent to be used may be any solvent that can dissolve the pitch, but the low solubility of the pitch, such as acetone, has a disadvantage in that the yield of carbonization is low because the amount of the extract is low and the molecular weight of the extract is low. Quinoline, on the other hand, has high pitch solubility but high boiling point, making it difficult to dry. Therefore, in the present invention, organic solvents showing tetrahydrofuran or pyridine or similar solubility are most preferred.

According to the present invention, since the mixing ratio of the pitch and the organic solvent varies depending on the type of the pitch and the organic solvent, it is difficult to limit the uniformity, and the mixing ratio is preferably determined in consideration of the viscosity according to the pitch and the organic solvent. In one embodiment, when coal tar pitch and tetrahydrofuran (organic solvent) are mixed, the mixing ratio is preferably 10-50% by weight of the pitch relative to the organic solvent. If it is less than 10% by weight, the coating layer is too thin to be activated after carbonization, and if it is more than 50% by weight, the viscosity is too high to uniformly coat it.

As described above, the pitch and the organic solvent are mixed and stirred, and the method is sufficient at room temperature using a conventional stirrer, and may be stirred for an appropriate time depending on the type and amount of the pitch and the organic solvent.

After stirring as described above, the mixture of pitch and organic solvent contains a component (soluble component) and an insoluble component (insoluble component) in the organic solvent among the pitch components. Since it is difficult to coat the fibers, the soluble components should be filtered and used. The extraction method at this time is more preferably a vacuum filtration method using a glass filter having a high filtration rate than using a filter paper.

According to the present invention, a mixture of thermosetting resin added to the extract is coated on a glass fiber to form a coating layer of pitch and thermosetting resin, wherein the thermosetting resin improves the adhesion between the coating layer and the glass fiber and further improves the specific surface area of the coating layer. Improve. Referring to the action of these thermosetting resins are as follows.

The coating layer of the thermosetting resin and the pitch coated on the glass fiber is converted into carbonaceous material by the carbonization treatment described below, and low molecular weight components having a low boiling point among the components of the thermosetting resin and the pitch are volatilized to escape into the gas. At this time, since the pitch is thermoplastic, the gas escapes and the remaining pores are filled again, whereas the thermosetting resin is already cured and the pores remain. Therefore, after the carbonization treatment, the thermosetting resin has a value whose specific surface area is much higher than the pitch. In other words, the specific surface area of the thermosetting resin is increased in the carbonization step before the activation treatment. In addition, since the thermosetting resin has good bonding property with glass fibers, it is possible to form a coating layer having a stronger bonding force.

As the thermosetting resin coated on the glass fiber according to the present invention, generally known phenol resins, furan resins or the like may be used. Although the amount of the thermosetting resin added varies depending on the pitch used and the type of the thermosetting resin, it is difficult to limit the amount of the thermosetting resin. However, the thermosetting resin is preferably 20 to 500 parts by weight based on 100 parts by weight. This is because when the amount of the thermosetting resin is added 20 parts or less, the added effect is small. On the contrary, when the amount of the thermosetting resin is 500 parts or more, the shrinkage is severe when the thermosetting resin is carbonized, and cracks are likely to occur in the coating layer.

According to the present invention, a thermosetting resin may be added to the extract and a curing agent may be added thereto. The type of the curing agent is not particularly limited, and generally used may be one used in general. Phosphoric acid is used in the case of phenol resin, and paratoluene sulfonic acid is used in the case of furan resin. In the embodiment of the present invention, a large change in specific surface area was not observed when the curing agent was added. However, as the amount of the curing agent is increased, the curing rate is increased. Although the addition amount of a hardening | curing agent should just be adjusted suitably according to a kind, about 0.1%-5.0% are enough.

As described above, the glass fiber is coated on the extract of the pitch to which the thermosetting resin is added, and the method may be soaked by soaking the glass fiber in the extract. The form of the glass fiber may be any filament bundle, woven or nonwoven fabric. At this time, the coating thickness is variable depending on the type and pitch of the organic solvent and the mixing amount of the organic solvent, so that it is difficult to limit the thickness, but according to one embodiment of the present invention, 1-5 μm is appropriate.

In order to volatilize the organic solvent in the mixture coated on the glass fiber and leave the pitch and the thermosetting resin in the coating layer as described above, the coating must be dried, and the drying is not special, and only the organic solvent is volatilized. For example, it may be sufficient to maintain at room temperature for about 12 hours, although it may be possible to apply a little heat in a short time, but applying too high heat is not preferable because the organic solvent may rapidly volatilize to form pores in the coating layer. .

After drying as described above may be directly carbonized, but in order to completely cure the thermosetting resin may be cured by heat treatment 1-270 hours at 70-200 ℃ depending on the type of thermosetting resin or curing agent. In addition, in order to prevent the coating layer from flowing down during the carbonization process, the coating layer may be stabilized by heat treatment at 250 to 400 ° C. for 10 minutes to 2 hours under an oxidizing atmosphere. This stabilization treatment may not be necessary in some cases.

Carbonization of the coating layer coated on the glass fiber according to the present invention is preferably heat-treated in an inert atmosphere at a temperature of 500-1000 ℃, which is insufficient carbonization below 500 ℃ and glass fiber deteriorates above 1000 ℃ to lower the strength or breakage Because it is easy to be.

Activation of the carbonized coating layer is performed while flowing steam at a constant temperature. Steam can be vaporized by using a syringe pump or flow meter to send water to the furnace at a constant flow rate. The activation temperature is good at 700-1000 ° C., because it takes too long or insufficient time to activate below 700 ° C. and above 1000 ° C., the glass fiber deteriorates and the strength is easily degraded or broken.

Hereinafter, the present invention will be described in detail through examples.

Example 1

After pulverizing the coal tar pitch having a softening point of 110 ° C., the mixture was mixed so that the pitch was 20% by weight with respect to tetrahydrofuran, followed by stirring for 4 hours, and then the tetrahydrofuran soluble powder using a glass filter and water aspirator. Was extracted. The phenol resin was added to the extract so as to be in the range of 10% by weight, followed by further stirring for 2 hours. Subsequently, the extract to which the phenolic resin was added was soaked in a glass fiber bundle, dried at room temperature for 24 hours, and carbonized at 600 ° C. for 1 hour in a nitrogen atmosphere. It was then activated by steam treatment at 800 ° C. for 4 hours. At this time, water vapor was generated by flowing a 250 ° C. heating furnace and a 500 ° C. heating furnace in sequence at a flow rate of 1 ml per minute. After activation, the thickness and specific surface area (measured by the BET method) of the coating layer were measured.

Measurement results,

Thickness of coating layer: 1.5 μm on average

Specific surface area: 90 cm 2 / g

Example 2

After grinding the coal tar pitch having a softening point of 110 ° C., the mixture was mixed so that the pitch was 25% by weight with respect to tetrahydrofuran, followed by stirring for 4 hours, and then the tetrahydrofuran soluble component was dissolved using a glass filter and water aspirator. Extracted. The phenol resin was added in an amount of 15% by weight based on the extract, and phosphoric acid, which is a curing agent, was added in an amount of 0.5% by weight, followed by further stirring for 2 hours, followed by coating with a glass fiber bundle. The coating layer was dried at room temperature for 24 hours and then cured by heat treatment at 100 ° C. in an oven maintained at 100 ° C. for 1 hour at 700 ° C. in a nitrogen atmosphere. It was then activated by steam treatment at 850 ° C. for 1 hour. At this time, water vapor was generated by flowing a 250 ° C. heating furnace and a 500 ° C. heating furnace in sequence at a flow rate of 1 ml per minute. After activation the coating layer measured the thickness and specific surface area.

Measurement results,

Coating layer thickness: average 1.8 μm

Specific surface area: 115㎠ / g

Example 3

After crushing the coal tar pitch having a softening point of 110 ° C., the mixture was mixed so that the pitch was 20% by weight with respect to tetrahydrofuran, followed by stirring for 4 hours, and then the tetrahydrofuran soluble powder was dissolved using a glass filter and water aspirator. Extracted. Furan resin was added to the extract in a ratio of 10% by weight, followed by further stirring for 2 hours. The furan resin-added extract was wetted with a glass fiber bundle and dried at room temperature for 24 hours. Subsequently, the glass fiber coated with the pitch extract to which the furan resin was added was placed in an oven and cured by heat treatment at 180 ° C. for 4 hours. It was then carbonized at 600 ° C. for 1 hour in a nitrogen atmosphere. It was then activated by steam treatment at 850 ° C. for 1 hour. At this time, water vapor was generated by flowing a 250 ° C. heating furnace and a 500 ° C. heating furnace in sequence at a flow rate of 1 ml per minute. After activation the coating layer measured the thickness and specific surface area.

Measurement results,

Thickness of coating layer: 1.5 μm on average

Specific surface area: 126㎠ / g

[Comparative Example]

As a result of omitting the addition of the phenolic resin in Example 1, the thickness of the coating layer was

The average was 1.5 탆 and the specific surface area was 50 cm 2 / g.

As described above, according to the present invention, since the coating layer of the pitch and the thermosetting resin is formed on the glass fiber, and only the coating layer is carbonized and activated, the mechanical properties such as the strength and abrasion resistance of the fiber itself are excellent. Since the adhesion of the fibers is improved, and in particular, the specific surface area of the coating layer is increased, there is an effect that the activated carbon fibers having excellent adsorption capacity can be provided at low cost.

Claims (2)

Mixing and stirring the pitch and the organic solvent to extract the soluble component; Adding and mixing the thermosetting resin to the extract; Coating the mixture on glass fibers and drying to volatilize an organic solvent; Carbonizing the coating layer by heat-treating the coated glass fiber from which the organic solvent was removed at an inert atmosphere at a temperature of 500-1000 ° C .; And Activating the glass fiber carbonized in the coating layer with a steam atmosphere at a temperature of 700-1000 ° C .; The method of claim 1, wherein the thermosetting resin is one selected from a phenol resin and a furan resin.