JP2688431B2 - Method for producing carbon-based hollow body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing a carbon-based hollow body which can be used in a wide range of fields such as a heat insulating material, a weight reducing material, a conductive plastic filler, and an adsorbent.

<Prior Art> Carbon-based hollow bodies are materials expected to be used as lightweight materials having excellent properties such as heat resistance, chemical resistance, and radiation resistance. Various methods are known as a method for manufacturing a carbon-based hollow body, and the most general method is a method using a bituminous material such as a thermoplastic organic polymer material, petroleum pitch, or coal pitch as a raw material. . That is, a raw material such as a bituminous material is uniformly mixed with an expanding agent such as a low boiling point solvent to obtain a powder having an appropriate particle size, and then carbonized by heating to obtain a carbon hollow body (Japanese Patent Publication No. Sho 49-30253, Japanese Patent Office Sho 61
-14110, JP-A-61-83239, etc.), a method of coating a core material such as a thermoplastic resin with a substance having a melting point higher than that of the core material to form a sphere having a multilayer structure and then heating and carbonizing it (Japanese Patent Publication No. 50-29837). Alternatively, a method in which a specific bituminous material is crushed and carbonized by heating (Japanese Patent Publication No. 54-10948) is known.

<Problems to be Solved by the Invention> Among the conventional methods, the method of using a swelling agent includes selecting a swelling agent suitable for each raw material, handling an organic solvent,
There is a problem that it is difficult to adjust the expansion agent-containing particles, and further it is difficult to set conditions and handle the heat treatment, and the method of passing through the multilayer structure can obtain only a hollow body having a relatively large particle diameter. was there. Furthermore, a method of pulverizing a bituminous material such as a specific coal and heating and carbonizing it is that a normal bituminous material often causes fusion between particles if it is attempted to heat and carbonize as it is, so that a raw material in a specific limited range is used. In addition to being difficult to operate because strict control of manufacturing conditions is required, the product obtained by this method has low purity because of the residual ash derived from the raw material coal etc. However, it is difficult to say that it is a true sphere, and there are problems that many of them have cracks in the shell, and it could only be used for limited applications such as heat insulating materials.

An object of the present invention is to provide a method for producing a spherical carbon-based hollow body, a metal-containing carbon-based hollow body or a porous carbon-based hollow body having a uniform particle size by a simple process.

<Means for Solving the Problems> The method of the present invention is substantially the same as a compound represented by the general formula — (CH ₂ ) _n —T _x — (CHR) _m — of aromatic sulfonic acids or salts thereof.
(In the formula, T is a benzene ring or a naphthalene ring, R is hydrogen, an alkyl group having 1 to 4 carbon atoms or a benzene ring,
n, m, x each represent 0 or 1, but both n and m are not 0), a condensate (hereinafter abbreviated as aromatic sulfonic acid condensate) by a bond, or the condensation A raw material composition consisting of a mixture of a body and a water-soluble polymer compound is subjected to heat treatment under an inert gas atmosphere or under reduced pressure after being made into fine particles, to perform expansion and carbonization or graphitization,
Further, it is a method for producing a carbon-based hollow body by performing activation treatment if necessary.

Examples of the aromatic sulfonic acid condensate used in the present invention include naphthalene sulfonic acid, anthracene sulfonic acid,
Phenatrene sulfonic acid, creosote oil, anthracene oil, sulfonated mixture of polycyclic aromatic compounds such as tar and pitch, toluene sulfonic acid, xylene sulfonic acid, phenol sulfonic acid and mixtures thereof or salts thereof. Aromatic sulfonic acid compounds such as, for example, formalin and paramin can be used as the aromatic sulfonic acid compounds or their salts, which are condensed by a method known per se so as to form a bond represented by the above general formula. It is general that they are bound using formaldehyde, hexamethylenetetramine or other aldehydes. As the cation component forming the aromatic sulfonate, Na ⁺ , K ⁺ , Ca ⁺² , NH ₄ ^{+ and the} like can be mentioned, but the ammonium salt is preferable from the viewpoint of easy handling in the subsequent carbon process. Is.

These aromatic sulfonic acid condensates may be appropriately purified and used, but usually, they may be used as a raw material as they are as a reaction mixture containing unreacted substances. Alternatively, a polymer of aromatic sulfonic acids having a methylene type bond, which is obtained by polymerizing aromatic sulfonic acids having a vinyl group such as polystyrene sulfonic acid, can be used as a raw material. Further, it goes without saying that these condensates can be used not only in a single composition but also in the form of a mixture or copolymerization or condensate of two or more condensates. As an example of the aromatic sulfonic acid condensate used in the present invention, an example of a formaldehyde condensate of naphthalene-β-ammonium sulfonate is shown. The condensate is a mixture of a monomer and a condensate of up to about 200 mer. And its number average molecular weight is about 20.
It is about 00 to 50,000. When dried, it becomes a weak solid that can be easily crushed.

The above-mentioned condensate is only one example of the condensate used in the present invention, and the range of the number of monomers constituting the condensate that can be used in the present invention or the number average thereof depending on the type of aromatic sulfonic acid and / or the salt thereof The molecular weight range is fixed. For example, in the case of a condensate of creosote oil sulfonate, the number average molecular weight is about 2000 in a mixture of monomers to about 40-mers.
In the case of a condensate of phenanthrenesulfonic acid, a mixture of monomers to about 30-mer having a number average molecular weight of about 2500 to 5000 can be used as the condensate in the present invention.

In the method of the present invention, the above-mentioned aromatic sulfonic acid condensate is dried and pulverized, and then, if necessary, fine powder components are removed to obtain fine particles of 1 to 1000 μm, and the fine particles are provided for the next expansion step. The particle size of the fine particles may be arbitrarily adjusted within the range of the particle size according to the properties of the target carbon-based hollow body, and a carbon-based hollow body having a uniform particle size can be obtained by performing an appropriate classification operation. . If the particle size is less than 1 μm, fusion between particles during expansion increases, and if it exceeds 1000 μm, it becomes difficult to maintain the true spherical shape of the particles after expansion, which is not preferable. In order to obtain the fine particles of the condensate, it is not always necessary to go through the steps of drying and pulverization, and the particles may be made into fine particles by means such as spray drying or dispersing the melt in an appropriate atmosphere. When the aromatic sulfonic acid condensate of the present invention is used as a raw material, a substantially spherical hollow body can be obtained from a pulverized product by a usual pulverizing means,
It is preferable that the particles have as few corners as possible, and for that purpose, it is preferable to carry out drying and granulation using a flash evaporator or the like.

Next, the fine particles of the aromatic sulfonic acid condensate are heated in the inert gas atmosphere to a maximum temperature of 450 to 600 ° C. and heat-treated.
This heat treatment partially decomposes the constituents of the condensate to generate gases such as ammonia, water and SO ₂ and the particles expand to obtain a temporary hollow body having a particle diameter of 1 to 4000 μm. The smaller the particle size of the condensate, the larger the specific surface area, so that the decomposed gas is more likely to be released to the outside of the particle and less likely to foam, so that it is necessary to increase the temperature rising rate during expansion. That is, the optimum heating rate varies depending on the size of the particles of the target hollow body and the raw material used, but it is usually 100 to 250 μm.
The temperature rising rate for obtaining the hollow body is 20 ℃ / min ~ 400 ℃ / mi
n, preferably 35 to 100 ° C / min. Temperature rising rate is 400 ° C /
Even if it exceeds min, the shape of the expanded particles becomes irregular, but a hollow body can be obtained. Therefore, if a strictly spherical hollow body is not strictly required, the heating rate may exceed 400 ° C./min.
If the amount of raw material particles to be heat-treated becomes too large or the amount of inert gas relative to the amount of raw material particles is too small, fusion between particles may occur, but to prevent this, heat treatment under reduced pressure It is effective to do. In the case of the aromatic sulfonic acid condensate used in the present invention, the expansion is 45
Almost complete at a temperature of 0-600 ° C.

The obtained primary hollow body can be used as it is depending on the application, but it is usually further carbonized, graphitized, and activated to obtain a highly functional carbon-based hollow body. That is, the primary hollow body is carbonized by heating in the temperature range of 500 to 3000 ° C. in an inert gas atmosphere after the expansion step or once taking out. The carbonization temperature can be appropriately selected depending on the application of the product. That is, explosive additive material,
When used as a buoyancy-imparting material, activated carbon or its raw material, carbonization at 500 to 800 ° C is sufficient.
For applications such as electromagnetic wave shielding materials, sustained-release carriers or catalysts, it is desirable to carry out carbonization or graphitization at a higher temperature of 800 to 3000 ° C. After or at the same time as the carbonization, the carbon-based hollow body having the function of activated carbon can be obtained by activating by treating with steam or CO ₂ at 800 to 1000 ° C.

In the method of the present invention, in the step of adjusting the powder of the aromatic sulfonic acid condensate, 0.02 to 20 per 100 parts by weight of the condensate.
By adding parts by weight of the water-soluble polymer compound, the final product performance such as handleability during powder preparation, fusion prevention during expansion and true sphere formation, or strength can be improved.

As the water-soluble polymer compound used in the present invention, a polymer compound soluble or colloidally dispersible in various kinds of water or an aqueous solvent can be used. Condensates of ethylene oxide, propylene oxide and the like or various alcohols, Polyalkylene oxide compounds such as fatty acid, alkylamine, and condensation products with alkylphenols, polyvinyl compounds such as polyvinyl alcohol and polyvinylpyrrolidone, polyacrylic acid compounds such as polyacrylic acid, polyacrylamide, acrylic acid-acrylamide copolymer, etc. It is particularly suitable. Further, among the methylene type condensates of aromatic sulfonic acids or their salts used as the main raw material in the method of the present invention, polystyrene sulfonic acid having high water solubility can be used as the water soluble polymer compound.

Further, by adding various metal salts to the raw material composition for expansion and carbonization, it is possible to obtain a carbon-based hollow body in which the metal components are extremely finely and uniformly dispersed. This metal-containing carbon-based hollow body can be used for various purposes by changing the type of metal salt used according to each purpose. That is, if zinc chloride or the like is used, activation treatment becomes easy and a high-performance activated carbon-based hollow body can be obtained, and if salts of copper, chromium, manganese, etc. are used, the deodorizing ability of activated carbon can be enhanced. it can. Further, by using a salt of iron, nickel, cobalt, molybdenum, gold, platinum or the like, a carbon-based hollow body having various catalytic activities,
By using a salt of iron, copper, etc., a carbon-based hollow body having a high electromagnetic wave shielding effect is obtained, and by using a salt of aluminum, zinc, etc., a carbon-based hollow body having good dispersibility in a metal, By using a salt of nickel, nickel, cobalt or the like, a carbon-based hollow body having magnetism can be obtained.

Hereinafter, the method of the present invention will be described more specifically with reference to Examples.

Example 1 1280 g of naphthalene having a purity of 95% was added with 1050 g of 98% sulfuric acid and reacted at 160 ° C. for 2 hours for sulfonation, and then unreacted naphthalene and reaction product water were distilled out of the system under reduced pressure. Then, 857 g of a 35% formalin aqueous solution was added, and the mixture was reacted at 105 ° C for 5 hours, neutralized with aqueous ammonia, filtered using No. 5 filter paper manufactured by Toyo Roshi Kaisha, Ltd., and the filtrate was evaporated to dryness to give a brown powder. An ammonium salt of a methylene-bonded condensate of naphthalene-β-sulfonic acid was obtained as a lump. The number average molecular weight of the condensate was 3,160. This brown lump is crushed and the particle size is adjusted to 100-150 μm, then in a nitrogen stream from room temperature to 200 ℃ 50 ℃ / min, 200 ℃ to 600 ℃ 35
℃ / min, increase the temperature from 600 ℃ to 800 ℃ at 40 ℃ / min.
Immediately after the temperature reached ℃, the product was expanded and carbonized to obtain a carbon-based hollow body at a yield of 48.5% (yield based on the dry weight of the condensate). As shown in the micrograph of FIG. 1, this was a spherical shape with a particle diameter of 200 to 300 μm, and the bulk density was 0.25 g / cm ³ .

The result of measuring the pore distribution of this carbon-based hollow body using a mercury porosimeter is as shown in Fig. 2. The center of the pore is 6 × 10 ³ Å, and its pore volume is 1.83cc / g. there were. Also, when observing the sample after measurement, since the mercury is still pressed into the sample and the sample is not broken at all, the pores with a center diameter of 6 × 10 ³ Å show through holes to the inside of the hollow body. It was confirmed that

Furthermore, when this carbon-based hollow body was activated at 900 ° C. for 30 minutes in a steam atmosphere, the BET specific surface area by N ₂ was 1624 m 2.
An activated carbon-based hollow body having a density of ² / g and a bulk density of 0.15 g / cm ³ could be obtained.

Example 2 1050 g of 98% sulfuric acid was added to 1700 g of creosote oil, and the temperature was increased to 160 ° C.
After reacting for 2 hours with sulfonation, the unreacted oil and the water produced by the reaction were distilled out of the system. Subsequently, 857 g of a 35% formalin aqueous solution was added, and the mixture was reacted at 105 ° C for 5 hours, neutralized with ammonia water, filtered using No.5 filter paper manufactured by Toyo Roshi Kaisha, Ltd., and the filtrate was evaporated to dryness to darkness. A brown mass was obtained. The number average molecular weight of this condensate was 2730. This dark brown lump
100 parts by weight of polyvinyl alcohol (manufactured by Wako Pure Chemical Industries,
After adding 2 parts by weight of a degree of polymerization of about 2000) and 20 parts by weight of ferric chloride to completely dissolve it by adding water, evaporate to dryness again and pulverize to adjust the particle size to 100 to 150 μm. Heat treatment was performed in the same manner as in (1) to obtain a carbon-based hollow body in which the iron component was uniformly and finely dispersed. This material exhibits magnetism and has a bulk density of 0.27
It was g / cm ³ . The center diameter of pores of this iron-containing carbon-based hollow body was 2.6 × 10 ² Å, and the pore volume (including the volume of the hollow portion) was 0.83 cc / g. When the carbon-based hollow body was washed with hydrochloric acid and the iron content was eluted, the central pore diameter was 1.3 × 10 ² Å
And the pore volume (including the volume of the hollow part) is 1.27.
Increased to cc / g.

Example 3 Naphthalene squeezed oil (composition naphthalene having a low boiling point of less than 4.2 wt%, naphthalene 26.4 wt%, β-methyl-naphthalene 49.0 wt%, α-methylnaphthalene 12.1 wt%, intermediate between naphthalene and α-methylnaphthalene) Boiling point fraction 4.0 wt%,
High-boiling fraction over the boiling point of α-methylnaphthalene 4.3wt
%) 1420 g of 98% sulfuric acid 1200 g was added, and the mixture was reacted at 150 ° C. for 3 hours for sulfonation, and then unreacted oil and water produced by reaction were distilled out of the system under reduced pressure. Then add 150 g of water, then 35
% Formalin aqueous solution (857 g) was added, and the mixture was reacted at 105 ° C. for 5 hours. Residual sulfuric acid equivalent calcium hydroxide was added, and sulfuric acid was filtered off as gypsum. After the filtrate was neutralized with aqueous ammonia, the water was evaporated using a flash evaporator to obtain a powder of an ammonium salt of a methylene bond type condensate of naphthalene pressed oil-sulfonic acid. The powder was classified to particles in the range of 37 to 53 μm, dropped into a vertical furnace kept at 800 ° C. under a N ₂ stream for expansion and carbonization to obtain a carbon-based hollow body. . This is a particle system
It is a spherical carbon-based hollow body with a diameter of 60 to 70 μm and a bulk density of 0.08.
It was g / cm ³ .

<Effect> According to the method of the present invention, an aromatic sulfonic acid condensate is used as a raw material, finely divided, expanded and carbonized,
By performing graphitization and activation treatment as necessary, a desired particle diameter can be obtained without using an expanding agent such as an organic solvent and without requiring an infusibilizing step necessary for carbonization of a usual pitch-based material. A carbon-based hollow body can be manufactured.
The carbon-based hollow body obtained by the method of the present invention has a substantially spherical shape, and is an amount having a through hole to the inside of the hollow body having a narrow pore size distribution, which is a heat insulating material, a conductive plastic filler, an electron wave shielding material, and a lightweight. It can be used for various purposes such as chemicals, sustained release drug capsules, explosives and adsorbents.

[Brief description of the drawings]

FIG. 1 is a drawing-substituting micrograph (magnification: 300) showing an example of the particle structure of a carbon-based hollow body obtained by the method of the present invention.
Times). FIG. 2 is a schematic diagram of a graph showing the results of measuring the pore distribution of an example of the carbon-based hollow body obtained by the method of the present invention, using a mercury porosimeter.

Claims (3)

(57) [Claims] 1. A substantially aromatic sulfonic acids or their salts, the formula _{- (CH 2) n -T x} - (CHR) m - ( wherein,
T is a benzene ring or naphthalene ring, R is hydrogen, an alkyl group having 1 to 4 carbon atoms or a benzene ring, n, m and x are 0 or 1, respectively, but n and m are not 0 at the same time. ) A condensate by a bond represented by, or a raw material composition comprising a mixture of the condensate and a water-soluble polymer compound,
A method for producing a carbon-based hollow body, which comprises subjecting to fine particles, followed by heat treatment in an inert gas atmosphere or under reduced pressure for expansion, carbonization or graphitization, and further activation treatment if necessary. 2. The method according to claim 1, wherein the metal-containing carbon-based hollow body is produced by adding a metal salt to the raw material composition. 3. The method according to claim 1, wherein a metal-containing hollow carbon body is obtained by adding a metal salt to the raw material composition, and then the metal is eluted by acid treatment or the metal is sublimated by high temperature heat treatment. A method for producing a porous carbon-based hollow body by: