JP7069524B2 - A carbon material precursor composition, a method for producing the same, and a method for producing a carbon material using the same. - Google Patents

Description

The present invention relates to a carbon material precursor composition, a method for producing the same, and a method for producing a carbon material using the same.

Conventionally, as a method for producing a carbon material such as carbon fiber, a method of heat-treating a carbon material precursor made of polyacrylonitrile under an inert atmosphere has been known (for example, Japanese Patent Application Laid-Open No. 2016-11276 (Patent). Document 1)). Since polyacrylonitrile used in this method is difficult to dissolve in an inexpensive general-purpose solvent, it is necessary to use an expensive organic solvent such as dimethyl sulfoxide or N, N-dimethylacetamide during polymerization or spinning, which is environmentally burdensome. There was a problem that the manufacturing cost of carbon material was high.

On the other hand, polyacrylamide is a water-soluble polymer, and since water, which is inexpensive and has a small environmental load, can be used as a solvent during polymerization and spinning, it is expected to reduce the production cost of carbon materials.

Japanese Unexamined Patent Publication No. 2016-11276

Since carbon materials are difficult to mold, in order to obtain carbon materials of a desired shape (for example, fibers, films), it is necessary to mold the carbon material precursor into a desired shape and then carbonize it. there were. However, when a carbon material precursor made of polyacrylamide formed into a desired shape is carbonized, there is a problem that the obtained carbon material does not always retain the desired shape before the carbonization treatment.

The present invention has been made in view of the above-mentioned problems of the prior art, and contains a carbon material precursor made of an acrylamide-based polymer, and retains a desired shape before carbonization even when carbonized. It is an object of the present invention to provide a carbon material precursor composition capable of producing, a method for producing the same, and a method for producing a carbon material using the same.

As a result of diligent research to achieve the above object, the present inventors have added at least one additive component selected from the group consisting of an acid and a salt thereof to a carbon material precursor composed of an acrylamide-based polymer and polyfunctionality. We have found that by adding a compound having a sex aldehyde group, a carbon material precursor composition capable of retaining a desired shape before the carbonization treatment can be obtained even when the carbonization treatment is performed, and the present invention has been completed. I came to do.

That is, the carbon material precursor composition of the present invention is at least one selected from the group consisting of a carbon material precursor composed of an acrylamide-based polymer containing 50 mol% or more of an acrylamide-based monomer unit, and a phosphoric acid and a salt thereof . Additives and glutaaldehyde, glyoxal, malondialdehyde, succinate dialdehyde, maleate dialdehyde, fumaric acid dialdehyde, tartrate dialdehyde, adipin dialdehyde, adipaldehyde, naphthalenedialdehyde, terephthalaldehyde, isophthalaldehyde, It contains a compound having at least one polyfunctional aldehyde group selected from the group consisting of dextrandialdehyde, saccharides oxidized by periodic acid, and phthaldialdehyde, and the content of the additive component is a carbon material. It is 0.1 to 30 parts by mass with respect to 100 parts by mass of the precursor, and the content of the compound having a polyfunctional aldehyde group is 0.1 to 70 parts by mass with respect to 100 parts by mass of the carbon material precursor. It is characterized by that.

In the carbon material precursor composition of the present invention, it is preferable that the amide group in the acrylamide-based polymer and the polyfunctional aldehyde group form a covalent bond.

The method for producing a carbon material precursor composition of the present invention is from an acrylamide-based polymer containing 50 mol% or more of an acrylamide-based monomer unit in the presence of at least one additive component selected from the group consisting of phosphoric acid and a salt thereof . Carbon material precursors and glutaraldehyde, glyoxal, malondialdehyde, succinate dialdehyde, maleate dialdehyde, fumaric acid dialdehyde, tartrate dialdehyde, adipin dialdehyde, adipaldehyde, naphthalenedialdehyde, terephthalaldehyde, A compound having at least one polyfunctional aldehyde group selected from the group consisting of isophthalaldehyde, dextrandialdehyde, saccharides oxidized by periodic acid, and phthaldialdehyde, and the amount of the additive component is a carbon material. The condition is 0.1 to 30 parts by mass with respect to 100 parts by mass of the precursor, and the amount of the compound having a polyfunctional aldehyde group is 0.1 to 70 parts by mass with respect to 100 parts by mass of the carbon material precursor. Below, it is characterized in that the carbon material precursor composition in which the covalent bond is formed is obtained by heating and reacting at a temperature of 250 ° C. or lower.

Further, the method for producing a carbon material of the present invention is characterized in that the carbon material precursor composition of the present invention is heat-treated at a temperature of 500 to 3000 ° C. under an inert atmosphere to carry out carbonization treatment. Is.

Although it is not always clear why the carbon material precursor composition of the present invention can retain the desired shape before carbonization even when carbonized, the present inventors have described as follows. I guess. That is, when the carbon material precursor composed of the acrylamide polymer is carbonized, the acrylamide polymer softens in the temperature raising process (particularly, in the temperature range of 200 to 250 ° C.), so that the shape before the carbonization treatment is maintained. It is difficult to obtain carbon material.

On the other hand, the carbon material precursor composition of the present invention has a carbon material precursor composed of an acrylamide-based polymer, at least one additive component selected from the group consisting of an acid and a salt thereof, and a polyfunctional aldehyde group. It contains a compound. In this carbon material precursor composition, the catalytic action of the additive component causes the dehydration reaction of the amide group of the acrylamide polymer and the polyfunctional aldehyde group of the compound having a polyfunctional aldehyde group to form a covalent bond. A crosslinked structure is introduced into the acrylamide polymer. For example, acrylamide-based polymers and glutaraldehyde have the following reaction formulas in the presence of an acid catalyst:

A covalent bond is formed by a dehydration reaction as in the above, and a crosslinked structure is introduced into the acrylamide-based polymer. When a carbon material precursor made of an acrylamide-based polymer having such a crosslinked structure is carbonized, the acrylamide-based polymer does not easily soften during the temperature rise process, so that the carbon material retains the desired shape before the carbonization treatment. It is presumed that it will be possible to obtain.

According to the present invention, it is possible to obtain a carbon material precursor composition containing a carbon material precursor made of an acrylamide-based polymer and capable of retaining a desired shape before carbonization even when carbonized. can. Further, by carbonizing the carbon material precursor composition of the present invention, it is possible to obtain a carbon material having a desired shape before the carbonization treatment.

It consists of a film made of the carbon material precursor composition obtained in Example 1, a film made of the carbon material precursor obtained in Comparative Example 1, and a comparative carbon material precursor composition obtained in Comparative Example 3. It is a graph which shows the temperature dependence of the storage elastic modulus of a film. It consists of a film made of the carbon material precursor composition obtained in Example 1, a film made of the carbon material precursor obtained in Comparative Example 1, and a comparative carbon material precursor composition obtained in Comparative Example 3. It is a graph which shows the temperature dependence of the elongation of a film.

Hereinafter, the present invention will be described in detail according to the preferred embodiment thereof.

First, the carbon material precursor composition of the present invention will be described. The carbon material precursor composition of the present invention is a compound having a carbon material precursor composed of an acrylamide polymer, at least one additive component selected from the group consisting of an acid and a salt thereof, and a polyfunctional aldehyde group (a compound having a polyfunctional aldehyde group. Hereinafter, it is referred to as "polyfunctional aldehyde group-containing compound"). By carbonizing the carbon material precursor composition of the present invention, a carbon material having a desired shape before the carbonization treatment can be obtained.

(Carbon material precursor)
The carbon material precursor used in the present invention is made of an acrylamide polymer. The acrylamide-based polymer may be a homopolymer of the acrylamide-based monomer or a copolymer of the acrylamide-based monomer and another polymerizable monomer, but the acrylamide-based polymer has a sufficiently crosslinked structure. From the viewpoint of obtaining a carbon material that has been introduced and sufficiently retains the desired shape before the carbonization treatment, those containing 50 mol% or more of acrylamide-based monomer units are preferable, and those containing 70 mol% or more of acrylamide-based monomer units. Is more preferable, those containing 90 mol% or more of acrylamide-based monomer units are further preferable, and homopolymers of acrylamide-based monomers are particularly preferable.

Examples of the acrylamide-based monomer include acrylamide; alkyl acrylamide such as N-methyl acrylamide; dialkyl acrylamide such as N, N-dimethyl acrylamide; dialkyl aminoalkyl acrylamide such as dimethyl aminoethyl acrylamide and dimethyl amino propyl acrylamide; N- ( Hydroxyalkyl acrylamide such as hydroxymethyl) acrylamide, N- (2-hydroxyethyl) acrylamide; Diacetone acrylamide; Methacrylate; Alkyl methacrylic amide such as N-methyl methacrylamide; Dialkyl methacrylic amide such as N, N-dimethyl methacrylic amide. Dialkylaminoalkylmethacrylates such as dimethylaminoethylmethacrylate, dimethylaminopropylmethacrylate; hydroxyalkylmethacrylates such as N- (hydroxymethyl) methacrylicamide, N- (2-hydroxyethyl) methacrylicamide; diacetonemethacrylate; Can be mentioned. Such an acrylamide-based monomer may be used alone or in combination of two or more. Among these acrylamide-based monomers, acrylamide is preferable from the viewpoint of excellent water solubility.

Examples of the other polymerizable monomer include vinyl cyanide-based monomers, unsaturated carboxylic acids and salts thereof, unsaturated carboxylic acid anhydrides, unsaturated carboxylic acid esters, vinyl-based monomers, and olefin-based monomers. Examples of the vinyl cyanide-based monomer include acrylonitrile, methacrylonitrile, 2-hydroxyethylacrylonitrile, chloroacrylonitrile, chloromethacrylonitrile, methoxyacrylonitrile, and methoxymethacrylonitrile. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, and itaconic acid, and examples of the unsaturated carboxylic acid anhydride include maleic anhydride, itaconic acid anhydride, and the like, and the unsaturated carboxylic acid ester. Examples thereof include methyl acrylate, methyl methacrylate and the like, examples of the vinyl-based monomer include styrene, α-methylstyrene, vinyl chloride and vinyl alcohol, and examples of the olefin-based monomer include ethylene and propylene. Can be mentioned. These other polymerizable monomers may be used alone or in combination of two or more. Among these other polymerizable monomers, acrylonitrile is preferable from the viewpoint of increasing the carbonization yield of the carbon material precursor composition.

The acrylamide-based polymer includes an aqueous solvent (water, N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethylacetamide (DMAC), etc., and a mixed solvent thereof) and an aqueous mixed solvent (the aqueous solvent). It is preferable that it is soluble in at least one of (a mixed solvent of) and an organic solvent (tetrahexyl, alcohol, acetonitrile, etc.). This enables wet mixing using the aqueous solvent or the aqueous mixed solvent when producing the carbon material precursor composition, and the acrylamide polymer, the additive component, and the polyfunctional aldehyde group-containing compound are mixed. It is possible to mix uniformly, at low cost and safely. Further, when molding the obtained carbon material precursor composition, dry molding (dry spinning), dry wet molding (dry wet spinning), and wet molding (wet spinning) using the aqueous solvent or the aqueous mixed solvent are used. ) Or electrospinning becomes possible, and it becomes possible to safely manufacture carbon materials at low cost. The content of the organic solvent in the aqueous mixed solvent is not particularly limited as long as the amount of the acrylamide polymer insoluble or sparingly soluble in the aqueous solvent is dissolved by mixing the organic solvent. Further, among such acrylamide-based polymers, the acrylamide-based polymer soluble in the aqueous solvent is preferable from the viewpoint of being able to safely produce a carbon material precursor composition and a carbon material at a lower cost. , Water-soluble (water-soluble) acrylamide-based polymers are more preferred.

As a method for producing such an acrylamide-based polymer, known polymerization methods such as solution polymerization, suspension polymerization, precipitation polymerization, dispersion polymerization, and emulsion polymerization (for example, reverse phase emulsion polymerization) can be adopted. When solution polymerization is adopted, the solvent is not particularly limited as long as it dissolves the raw material monomer and the obtained acrylamide-based polymer, but from the viewpoint of low cost and safe production, the aqueous solvent (water, N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethylacetamide (DMAC), etc., and a mixed solvent thereof, etc.) or the aqueous mixed solvent (the aqueous solvent and the organic solvent (tetratetra, alcohol, acetonitrile, etc.)). It is preferable to use (a mixed solvent with), it is more preferable to use the aqueous solvent, and it is particularly preferable to use water. Further, as the polymerization initiator, at least one of the aqueous solvent such as 4,4'-azobis (4-cyanovaleric acid), ammonium persulfate, potassium persulfate and the aqueous mixed solvent (preferably the aqueous solvent, More preferably, a radical polymerization initiator soluble in water) can be mentioned.

(Additional ingredients)
The additive component used in the present invention is at least one selected from the group consisting of an acid and a salt thereof, and dehydration of the amide group of the acrylamide-based polymer and the polyfunctional aldehyde group of the polyfunctional aldehyde group-containing compound. It acts as a catalyst in the reaction. Examples of the acid include inorganic acids such as phosphoric acid, polyphosphoric acid, boric acid, nitric acid and carbonic acid, and organic acids such as oxalic acid, citric acid and sulfonic acid. Examples of such acid salts include metal salts (for example, sodium salts and potassium salts), ammonium salts, amine salts and the like, and ammonium salts and amine salts are preferable, and ammonium salts are more preferable. In particular, among these additive components, phosphoric acid and a salt thereof are preferable from the viewpoint of obtaining high catalytic activity in the reaction between the amide group of the acrylamide-based polymer and the polyfunctional aldehyde group of the polyfunctional aldehyde group-containing compound. , Phosphorus, ammonium salts of phosphoric acid are more preferred. Further, phosphoric acid, polyphosphoric acid, boric acid, and ammonium salts thereof are preferable from the viewpoint of further improving the carbonization yield of the obtained carbon material precursor, and phosphoric acid, polyphosphoric acid, boric acid, and ammonium thereof. Salts are more preferred, and phosphoric acid, polyphosphoric acid, ammonium salts of phosphoric acid, ammonium salts of polyphosphoric acid are particularly preferred.

The additive component is preferably a component that is soluble in at least one of the aqueous solvent and the aqueous mixed solvent (preferably the aqueous solvent, more preferably water). This enables wet mixing using the aqueous solvent or the aqueous mixed solvent when producing the carbon material precursor composition, and the acrylamide polymer, the additive component, and the polyfunctional aldehyde group-containing compound are mixed. It is possible to mix uniformly, at low cost and safely. Further, when molding the obtained carbon material precursor composition, dry molding (dry spinning), dry wet molding (dry wet spinning), and wet molding (wet spinning) using the aqueous solvent or the aqueous mixed solvent are used. ) Or electrospinning becomes possible, and it becomes possible to safely manufacture carbon materials at low cost.

(Polyfunctional aldehyde group-containing compound)
The polyfunctional aldehyde group-containing compound used in the present invention undergoes a dehydration reaction with an acrylamide-based polymer to covalently bond to form a crosslinked structure. Examples of the polyfunctional aldehyde group-containing compound include glutaraldehyde, glyoxal, malondialdehyde, succinic acid dialdehyde, maleic acid dialdehyde, fumaric acid dialdehyde, tartrate acid dialdehyde, adipin dialdehyde, adipaldehyde, and naphthalenedialdehyde. , Telephthalaldehyde, isophthalaldehyde, dextrandialdehyde, saccharides oxidized by periodic acid, phthaldialdehyde and the like. Such a polyfunctional aldehyde group-containing compound may be used alone or in combination of two or more. Among these polyfunctional aldehyde group-containing compounds, glutaraldehyde is preferable from the viewpoint of reactivity with an acrylamide-based polymer.

The polyfunctional aldehyde group-containing compound is preferably a component that is soluble in at least one of the aqueous solvent and the aqueous mixed solvent (preferably the aqueous solvent, more preferably water). This enables wet mixing using the aqueous solvent or the aqueous mixed solvent when producing the carbon material precursor composition, and the acrylamide polymer, the additive component, and the polyfunctional aldehyde group-containing compound are mixed. It is possible to mix uniformly, at low cost and safely. Further, when molding the obtained carbon material precursor composition, dry molding (dry spinning), dry wet molding (dry wet spinning), and wet molding (wet spinning) using the aqueous solvent or the aqueous mixed solvent are used. ) Or electrospinning becomes possible, and it becomes possible to safely manufacture carbon materials at low cost.

[Carbon material precursor composition]
The carbon material precursor composition of the present invention contains the carbon material precursor made of the acrylamide-based polymer, the additive component, and the polyfunctional aldehyde group-containing compound. Further, in such a carbon material precursor composition of the present invention, the amide group of the acrylamide-based polymer and the polyfunctional aldehyde group of the polyfunctional aldehyde group-containing compound form a covalent bond. preferable. As a result, since the crosslinked structure is introduced into the acrylamide-based polymer, the softening of the acrylamide-based polymer is suppressed, and a carbon material having a desired shape before the carbonization treatment can be obtained.

In such a carbon material precursor composition of the present invention, as the content of the polyfunctional aldehyde group-containing compound, the content of the crosslinked structure in the acrylamide-based polymer increases, and the softening of the acrylamide-based polymer is more sufficient. From the viewpoint of obtaining a carbon material that is sufficiently suppressed and sufficiently retained the desired shape before the carbonization treatment, 0.1 to 70 parts by mass is preferable with respect to 100 parts by mass of the carbon material precursor, and 0. 2 to 30 parts by mass is more preferable, 1 to 20 parts by mass is further preferable, and 1 to 10 parts by mass is particularly preferable. As for the content of the additive component, sufficient catalytic activity is obtained in the dehydration reaction between the amide group of the acrylamide polymer and the polyfunctional aldehyde group of the polyfunctional aldehyde group-containing compound, and the carbon material precursor is also obtained. From the viewpoint of improving the carbonization yield of the body composition, 0.1 to 30 parts by mass is preferable, 0.1 to 20 parts by mass is more preferable, and 1 to 10 parts by mass is preferable with respect to 100 parts by mass of the carbon material precursor. The mass portion is more preferable.

Further, the aqueous solution or the aqueous mixture solution containing the carbon material precursor composition of the present invention has a low viscosity even when the concentration of the carbon material precursor is high (for example, 20% by mass or more). , Excellent molding processability. Specifically, the viscosity of the aqueous solution or the aqueous mixture solution in which the concentration of the carbon material precursor is 30% by mass is preferably 20 Pa · s or less at room temperature and a shear rate of 10 s ^-1 . .. Thereby, for example, when a film is formed by a solution casting method using the aqueous solution or the aqueous mixed solution, a film having less thickness unevenness (10% or less) and an excellent surface appearance can be obtained. On the other hand, when the viscosity of the aqueous solution or the aqueous mixed solution exceeds 20 Pa · s, the surface appearance of the obtained film tends to deteriorate, and when it exceeds 100 Pa · s, the thickness unevenness of the obtained film becomes large ( It tends to be more than 10%), and if it exceeds 200 Pa · s, the handleability at the time of casting is low, and even if a film cannot be obtained or a film is obtained, bubbles are contained in the film and the thickness unevenness is further increased. It tends to be large (more than 20%).

As a method for producing the carbon material precursor composition of the present invention, the carbon material obtained by directly mixing (melting and mixing) the additive component and the polyfunctional aldehyde group-containing compound with the carbon material precursor in a molten state. A method for forming a precursor composition into a desired shape (for example, a film, a sheet, a fibrous, or a lump), a dry blend of the carbon material precursor, the additive component, and the polyfunctional aldehyde group-containing compound (for example). Dry mixing) to form the obtained carbon material precursor composition into a desired shape (eg, film, sheet, fibrous, lump), the additive components and the polyfunctional aldehyde group-containing compound. The carbon material precursor having the desired shape (for example, film-like, sheet-like, fibrous, lump-like) is immersed in or passed through the contained aqueous solution or aqueous mixed solution to form a carbon material having the desired shape. A method for obtaining a precursor composition, a solvent in which the carbon material precursor is insoluble (for example, alcohol, acetone, chlorine-based solvent, ether-based solvent, ester-based solvent, aromatic solvent), the additive component, and the polyfunctionality. The carbon material precursor formed into a desired shape (for example, film-like, sheet-like, fibrous, or lump-like) is immersed in or passed through a solution containing an aldehyde group-containing compound to obtain a desired shape of carbon. It is also possible to adopt a method for obtaining a material precursor composition, but the carbon material precursor, the additive component and the polyfunctional aldehyde group-containing compound to be used can be used as the aqueous solvent or the aqueous mixed solvent. When it is a solvent, the carbon material precursor, the additive component, and the polyfunctional aldehyde group-containing compound can be uniformly mixed from the viewpoint that the carbon material precursor, the additive component, and the polyfunctional aldehyde group-containing compound can be uniformly mixed. The functional aldehyde group-containing compound is mixed (wet mixed) in the aqueous solvent or the aqueous mixed solvent, and the obtained solution is used to form a carbon material precursor composition in a desired shape (for example, film-like or sheet-like). , Fibrous, lumpy), and then the solvent is removed. Further, in the wet mixing, it is preferable to use the aqueous solvent as the solvent, and it is more preferable to use water, from the viewpoint that the carbon material precursor composition can be safely produced at a lower cost. Further, the method for removing the solvent is not particularly limited, and known drying methods such as hot air drying, vacuum drying, and freeze drying can be adopted, but hot air drying is preferable from the viewpoint of simple equipment. ..

Further, in the method for producing a carbon material precursor composition of the present invention, a carbon material precursor composition having a desired shape is heat-treated at a temperature of 250 ° C. or lower (preferably 200 ° C. or lower) to obtain the additive component. In the presence of the carbon material precursor, it is preferable to cause a dehydration reaction between the carbon material precursor and the compound having a polyfunctional aldehyde group. This promotes the formation of a covalent bond between the amide group of the acrylamide-based polymer and the polyfunctional aldehyde group of the polyfunctional aldehyde group-containing compound, and the crosslinked structure is sufficiently introduced into the acrylamide-based polymer. As a result, it is possible to obtain a carbon material in which the softening of the acrylamide-based polymer is more sufficiently suppressed and the desired shape before the carbonization treatment is sufficiently retained. The lower limit of the heating temperature is preferably room temperature (25 ° C.) or higher, and more preferably 50 ° C. or higher, from the viewpoint that the effect of heating can be sufficiently obtained. The heating time is preferably 1 minute to 50 hours, more preferably 1 minute to 5 hours.

[Manufacturing method of carbon material]
Next, the method for producing the carbon material of the present invention will be described. In the method for producing a carbon material of the present invention, the carbon material precursor composition of the present invention is subjected to an inert atmosphere (in an inert gas such as nitrogen, argon or helium) at 500 to 3000 ° C. (preferably 500 to 2500). The carbonization treatment is carried out by performing the heat treatment at a temperature of ° C., more preferably 1000 to 2000 ° C.). This makes it possible to obtain a carbon material that sufficiently retains the desired shape before the carbonization treatment. The heating time in the carbonization treatment is preferably 1 minute to 50 hours.

Further, in the method for producing a carbon material of the present invention, the carbon material precursor composition of the present invention is heat-treated (flame-resistant treatment) in an oxidizing atmosphere (for example, in air) before the carbonization treatment. You may. As a result, the additive component in the carbon material precursor composition acts to convert the structure of the acrylamide-based polymer into a structure having high heat resistance, so that the carbonization yield of the carbon material precursor is improved. In addition, a crosslinked structure can be introduced into the acrylamide-based polymer by this flameproofing treatment. The heating temperature in such a flame resistant treatment is preferably 500 ° C. or lower, more preferably 150 to 400 ° C., and even more preferably 200 to 350 ° C. Further, the heating time in the flame resistance treatment is not particularly limited, and for example, heating for more than 1 hour is possible, but from the viewpoint of reducing the manufacturing cost, 1 to 60 minutes is preferable.

Further, in the method for producing a carbon material of the present invention, the carbon material precursor composition to be used is previously formed into a desired shape (for example, in the form of a film, before the carbonization treatment (in the case of performing the flame resistance treatment)). It is preferable to mold it into a sheet shape, a fibrous shape, or a lump shape). At this time, the carbon material precursor composition is pressure-molded as it is, or melt-molded (for example, melt cast molding, melt extrusion molding, injection molding, melt spinning) using the molten carbon material precursor composition. However, when the carbon material precursor composition of the present invention is soluble in the aqueous solvent or the aqueous mixed solvent, the carbon material precursor composition may be used as the aqueous solution from the viewpoint of improving molding processability. It is preferable to dissolve in a solvent or the aqueous mixed solvent and use the obtained aqueous solution or aqueous mixed solution for molding. As such a molding method, solution cast molding, wet molding (wet spinning), dry wet molding (dry wet spinning), dry molding (dry spinning), and electrospinning are preferable. Thereby, the carbon material precursor composition having a desired shape can be safely produced at low cost. Further, from the viewpoint that the carbon material can be safely produced at a lower cost, it is more preferable to use the aqueous solvent as the solvent, and it is particularly preferable to use water.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. The acrylamide homopolymer used in Examples and Comparative Examples was synthesized by the following method.

(Synthesis Example 1)
After dissolving 10 g (140 mmol) of acrylamide (AAm) in 90 g of water, nitrogen substitution was performed by repeating depressurization and introduction of nitrogen gas using a vacuum pump. Next, an aqueous potassium persulfate solution (50 mg of potassium persulfate dissolved in 1.1 ml of water) and 50 μl of tetramethylethylenediamine were added under a nitrogen stream, and after further nitrogen substitution, a magnetic stirrer was placed under a nitrogen stream. Used to stir. After 30 minutes had passed from the start of stirring, the stirrer stopped rotating due to the increase in viscosity, but the reaction was continued for 12 hours. Then, 350 ml of water was added, and the mixture was uniformly stirred using a mechanical stirrer to obtain an aqueous solution of an acrylamide homopolymer (PAAm) (PAAm concentration: 22 g / L).

(Comparative Example 1)
1.1 g of the PAAm aqueous solution obtained in Synthesis Example 1 was placed in a petri dish made of Teflon (registered trademark) having a diameter of 40 mm, dried in a constant temperature bath at 70 ° C. for 1 hour, and PAAm having a thickness of 20 to 30 μm and a mass of 34 mg. A film made of (carbon material precursor) was obtained.

(Comparative Example 2)
The PAAm film prepared in the same manner as in Comparative Example 1 was immersed in a mixed solution of 2 ml of a 25% glutaraldehyde aqueous solution and 8 ml of ethanol for 3 days. Then, the film was taken out and dried by heating at 120 ° C. for 1 hour to obtain a film composed of a comparative carbon material precursor composition containing PAAm (carbon material precursor) and glutaraldehyde.

(Comparative Example 3)
The PAAm film prepared in the same manner as in Comparative Example 1 was immersed in a mixed solution of 0.2 ml of phosphoric acid (85%) and 8 ml of ethanol for 3 days. Then, the film was taken out and dried by heating at 120 ° C. for 1 hour to obtain a film composed of a comparative carbon material precursor composition containing PAAm (carbon material precursor) and phosphoric acid.

(Example 1)
The PAAm film prepared in the same manner as in Comparative Example 1 was immersed in a mixed solution of 2 ml of a 25% glutaraldehyde aqueous solution, 0.2 ml of phosphoric acid (85%) and 8 ml of ethanol for 3 days. Then, the film was taken out and dried by heating at 120 ° C. for 1 hour to obtain a film composed of a carbon material precursor composition containing PAAm (carbon material precursor), glutaraldehyde and phosphoric acid.

<Carbonization>
The films obtained in Examples 1 and Comparative Examples 1 to 3 were cut into 1.5 cm × 1.25 cm rectangles, placed in a 2.5 cm diameter tube furnace, and placed in a 5 cm diameter quartz tube furnace at 500 ml / min. The temperature was raised from room temperature to 900 ° C. over 4 hours under a nitrogen stream, and then heated at 900 ° C. for 1 hour for carbonation treatment.

The appearance of the obtained carbon material was visually observed. Further, the ratio of the area of the portion of the carbon material produced as a self-supporting film without melting or sticking to the crucible (film shape retention rate) was determined. Further, the mass of the carbon material was measured, and the ratio (carbonization yield) to the initial mass (mass of the carbon material precursor) was determined. The results are shown in Table 1.

As shown in Table 1, a carbon material precursor composed of PAAm (Comparative Example 1) and a comparative carbon material precursor composition composed of PAAm and glutaraldehyde (Comparative Example 2) are heat-treated (carbonized) at 900 ° C. After the treatment), the PAAm melted and the film shape before the carbonization treatment could not be maintained. Further, when phosphoric acid was added to PAAm (Comparative Example 3), PAAm was partially melted by heat treatment (carbonization treatment) at 900 ° C., but the obtained carbon material was a film before carbonization treatment. 40% of the shape was retained.

On the other hand, when glutaraldehyde and phosphoric acid were added to PAAm (Example 1), the film shape before the carbonization treatment was maintained even after the heat treatment (carbonization treatment) at 900 ° C. This is because the amide group of PAAm and the aldehyde group of glutaraldehyde undergo a dehydration reaction by the catalytic action of phosphoric acid to form a covalent bond in the heat drying when a film made of a carbon material precursor composition is produced. It is probable that the cross-linked structure was introduced in.

Further, when phosphoric acid was added to PAAm (Comparative Example 3), the carbonization yield was higher than when only PAAm was added (Comparative Example 1) or when glutaraldehyde was added (Comparative Example 2). It was found that when glutaraldehyde and phosphoric acid were added to PAAm (Example 1), the carbonization yield was further increased.

From the above results, even if glutaraldehyde and phosphoric acid are added to the carbon material precursor made of PAAm and heat treatment (carbonization treatment) is performed at a high temperature, the shape before the carbonization treatment (carbon material precursor). It was confirmed that a carbon material can be obtained with a high carbonization yield while maintaining the shape).

<Viscoelasticity test>
The films obtained in Examples 1 and Comparative Examples 1 and 3 were cut into 2 cm × 0.5 cm rectangles, and used at room temperature under the conditions of an atmospheric atmosphere, a strain of 0.5%, and a frequency of 10 Hz using a viscoelastic spectrometer. The viscoelasticity was measured while raising the temperature to 370 ° C. at 5 ° C./min. FIG. 1 is a graph showing the temperature dependence of the storage elastic modulus, and FIG. 2 is a graph showing the temperature dependence of elongation.

In the films obtained in Comparative Examples 1 and 3, as shown in FIG. 1, it was found that the storage elastic modulus began to decrease from around 200 ° C. and softened. Further, as shown in FIG. 2, the elongation increased due to softening in the temperature range of 250 ° C. or higher. On the other hand, in the film obtained in Example 1, as shown in FIG. 1, the decrease in the storage elastic modulus in the temperature range of 200 ° C. or higher was smaller than that in the films obtained in Comparative Examples 1 and 3. In addition, elongation in the temperature range of 250 ° C. or higher was suppressed. This is because in the carbon material precursor composition of the present invention (Example 1) containing PAAm, glutaraldehyde and phosphoric acid, the amide group of PAAm and the aldehyde group of glutaraldehyde are dehydrated by the catalytic action of phosphoric acid. It is considered that the covalent bond was formed by the reaction and the crosslinked structure was introduced into PAAm. On the other hand, in the carbon material precursor consisting only of PAAm (Comparative Example 1) and the comparative carbon material precursor composition containing PAAm and phosphoric acid (Comparative Example 3), glutaraldehyde does not exist and the crosslinked structure is formed. Since it was not formed, it is considered that softening and elongation occurred.

From the above results, by adding glutaraldehyde and phosphoric acid to the carbon material precursor composed of PAAm, the softening of PAAm in the temperature range of 200 ° C. or higher is suppressed, and the elongation in the temperature range of 250 ° C. or higher is also suppressed. It turned out that.

As described above, according to the present invention, a carbon material precursor containing a carbon material precursor made of an acrylamide-based polymer and capable of retaining a desired shape before carbonization treatment even when carbonized. It becomes possible to obtain the composition.

Therefore, since the method for producing a carbon material of the present invention is a method using such a carbon material precursor composition, it is possible to produce a carbon material having a desired shape before carbonization treatment. It is useful as a method.

Claims (4)

A carbon material precursor made of an acrylamide polymer containing 50 mol% or more of an acrylamide monomer unit, at least one additive component selected from the group consisting of phosphoric acid and a salt thereof , and glutaaldehyde, glyoxal, malondialdehyde, Dialdehyde succinate, dialdehyde maleate, dialdehyde fumarate, dialdehyde tartrate, adipine dialdehyde, adipaldehyde, naphthalenedialdehyde, terephthalaldehyde, isophthalaldehyde, dextrandialdehyde, saccharides oxidized by periodic acid, And a compound having at least one polyfunctional aldehyde group selected from the group consisting of phthaldialdehyde .
The content of the additive component is 0.1 to 30 parts by mass with respect to 100 parts by mass of the carbon material precursor.
The content of the compound having a polyfunctional aldehyde group is 0.1 to 70 parts by mass with respect to 100 parts by mass of the carbon material precursor.
A carbon material precursor composition characterized by that. The carbon material precursor composition according to claim 1, wherein the amide group in the acrylamide-based polymer and the polyfunctional aldehyde group form a covalent bond. In the presence of at least one additive component selected from the group consisting of phosphoric acid and salts thereof , a carbon material precursor consisting of an acrylamide-based polymer containing 50 mol% or more of an acrylamide-based monomer unit, and glutaaldehyde, glyoxal, and malondi. Aldehyde, succinic acid dialdehyde, maleate dialdehyde, fumaric acid dialdehyde, tartrate dialdehyde, adipin dialdehyde, adipaldehyde, naphthalenedialdehyde, terephthalaldehyde, isophthalaldehyde, dextrandialdehyde, periodic acid A compound having at least one polyfunctional aldehyde group selected from the group consisting of saccharides and phthaldialdehyde, the amount of the additive component is 0.1 to 30 mass by mass with respect to 100 parts by mass of the carbon material precursor. The reaction is carried out by heating at a temperature of 250 ° C. or lower under the condition that the amount of the compound having a polyfunctional aldehyde group is 0.1 to 70 parts by mass with respect to 100 parts by mass of the carbon material precursor. 2. A method for producing a carbon material precursor composition, which comprises obtaining the carbon material precursor composition according to claim 2. A method for producing a carbon material, which comprises subjecting the carbon material precursor composition according to claim 1 or 2 to a heat treatment at a temperature of 500 to 3000 ° C. in an inert atmosphere to carry out a carbonization treatment.

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