JP6058969B2 - Method for producing metal oxide fiber - Google Patents

Description

  The present invention relates to a method for producing metal oxide fibers. The metal oxide fiber obtained by the production method of the present invention can be suitably used as a material constituting, for example, a filler, a catalyst carrier, an electrode material, a filter, and the like.

  Since perovskite metal oxides have electrical conductivity and oxide ion conductivity, their use as electrode materials and the like has been studied. When this perovskite type metal oxide is in a fiber form, it is considered that the electrical conductivity and oxide ion conductivity are further excellent, and therefore a fibrous perovskite type metal oxide has been proposed.

  For example, Japanese Unexamined Patent Application Publication No. 2009-197351 (Patent Document 1) states that “a fibrous ceramic material made of a perovskite oxide material, which is a 3d transition metal of Fe, Mn, Co, Ni, Ca, Ba, Sr. A fibrous ceramic material comprising a crystalline perovskite oxide material containing at least two kinds of alkaline earth metals and rare earth metals has been proposed. In Patent Document 1, as a method for producing a fibrous ceramic material, a metal salt is dissolved in distilled water, and a predetermined amount of a water-soluble polymer is mixed therein to produce a metal salt gel as a precursor. A manufacturing method is disclosed in which a body is spun by electrospinning and calcined. However, in this method, the precursor contains a large number of metal ions, and the metal ions are recrystallized into a metal salt due to a decrease in solubility caused by mixing a water-soluble polymer. This is a method in which the tip of the wire is clogged and cannot be stably spun for a long time.

  The applicant of the present application stated that “a method for producing inorganic nanofibers by an electrospinning method using a sol solution mainly composed of an inorganic component, the sol solution comprising a highly reactive metal alkoxide and a salt catalyst. And the salt catalyst is an amine compound having a N—N bond, a N—O bond, a N—C═N bond, or a N—C═S bond. (Patent Document 2). This production method was a method capable of stably producing inorganic nanofibers excellent in handleability such as strength over a long period of time. However, since it is necessary to synthesize a sol from a metal alkoxide, a desired metal oxide fiber cannot be produced when the sol cannot be synthesized.

JP 2009-197351 A JP 2010-168720 A

  The present invention has been made under such circumstances, and even when the sol cannot be synthesized, such as perovskite-type metal oxide fibers, the metal oxide fibers can be stably stabilized over a long period of time. An object is to provide a method capable of spinning.

The invention according to claim 1 of the present invention includes: “a step of preparing a spinning solution in which a metal salt and a maleic anhydride-based polymer capable of coordinating with a metal ion of the metal salt are dissolved, spinning the spinning solution” And a step of forming a coordination bond fiber, and a step of manufacturing a metal oxide fiber by firing the coordination bond fiber. ”

  In the invention according to claim 1 of the present invention, the polymer capable of coordinating with the metal ion of the metal salt is coordinated with the metal ion, thereby stabilizing the metal ion and preventing recrystallization of the metal ion. it can. Therefore, it is possible to perform stable spinning over a long time without clogging the nozzle tip. As a result, metal oxide fibers can be produced stably over a long period of time.

  In addition, when a spinning solution prepared by dissolving a conventional metal salt in water and mixing a predetermined amount of polymer with this is to be electrospun, the conductivity of the spinning solution is high and spinning cannot be performed stably. However, when the polymer capable of coordinating with the metal ion of the metal salt is coordinated with the metal ion, the ratio of free metal ions in the spinning solution is reduced, and the electrical conductivity of the spinning solution is reduced. Since it becomes moderately low, stable spinning can be achieved even when spinning by an electrostatic spinning method. In particular, when an organic solvent is included as a solvent in the spinning solution, the electrical conductivity of the spinning solution is further lowered, so that more stable spinning is possible and stable spinning is possible for a longer time. As a result, metal oxide fibers can be produced stably over a long period of time.

Schematic side view of an apparatus that can spin fibers by electrostatic spinning Schematic side view of an apparatus capable of spinning fibers by applying gas shearing force in addition to electric field action Electron micrograph of the main surface of the metal oxide fiber sheet in Example 1 Electron micrograph of the main surface of the metal oxide fiber sheet in Example 2 Electron micrograph of the main surface of the metal oxide fiber sheet in Example 3 Electron micrograph on the main surface of the metal oxide fiber sheet in Comparative Example 1

  In the method for producing a metal oxide fiber of the present invention, first, a step of preparing a spinning solution in which a metal salt and a polymer capable of coordinating with a metal ion of the metal salt are dissolved is performed.

  This metal salt is appropriately selected depending on the metal oxide fiber to be produced. The metal salt is not particularly limited. For example, lithium, beryllium, boron, carbon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron , Cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, cadmium, indium, tin, antimony, tellurium, cesium, barium, lanthanum, hafnium, tantalum, tungsten , Mercury, thallium, lead, bismuth, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, yttrium Terbium, or metal halides such as lutetium, nitrate, can be used one or more sulfate, acetate, and oxalic acid salt. Among these, acetate is preferable because it does not lower the pH and is easy to handle even when dissolved in a solvent. Nitrate is preferable because it is easily dissolved in a solvent.

  In the present invention, in the spinning solution, a polymer capable of coordinating with the metal ion of the metal salt as described above (hereinafter sometimes referred to as “coordination polymer”) is coordinated with the metal ion. This stabilizes metal ions, prevents recrystallization of metal ions, and enables stable spinning over a long period of time without clogging the nozzle tip, resulting in long-term stability of metal oxide fibers. Manufacturing was possible. By coordinating the metal ions and the coordination polymer, the abundance ratio of free metal ions in the spinning solution is lowered, and the electrical conductivity of the spinning solution is lowered appropriately, thereby enabling the electrostatic spinning method. Even when spinning, stable spinning is possible.

Such a coordination polymer is not particularly limited as long as it can be coordinate-bonded by giving a lone pair to a metal ion of a metal salt. For example, it becomes the center of a coordination group. As the donor atom, a coordination polymer having a coordination group composed of O, S, N, or C can be used. As a more specific coordination group, when the donor atom is O, H ₂ O, HO ⁻ , O ²⁻ , NO ₂ ⁻ , NO ₃ ⁻ , CO ₃ ²⁻ , PO ₄ ³⁻ , ClO ₄ ⁻ , When ROH, RO ⁻ , R ₂ O, R ₂ C═O, R—COO ⁻ , R—N═O, and the donor atom is S, H ₂ S, HS ⁻ , S ²⁻ , S ₂ O ₃ ²⁻ , NCS ⁻ , RSH, RS ⁻ , R ₂ S, R ₂ C═S, R—COS ⁻ , R-CSS ⁻ , when the donor atom is N, H ₃ N, H ₂ N ⁻ , HN ²⁻ , N ^{_{3-, O 2 N -, SCN}} -, R 2 C = N-OH, RH 2 N, R 2 HN, R 3 N, R 2 C = NR, R-N = NR, donor atoms C In this case, N≡C—, O≡C, RN≡C, RC≡C— and the like can be mentioned (where R represents an alkyl group).

  More specifically, examples of the coordination polymer include maleic anhydride polymers, carboxylic acid polymers, amino alcohol polymers, porphyrin arrays, thiocyanic acid polymers, and ethylenediamine polymers. In particular, a coordination polymer that can coordinately bond with a polyvalent metal ion in the molecule, such as a maleic acid polymer, is preferable. Coordination bonds between metal ions between molecules limit the movement of the coordination polymer, causing the spinning solution to become highly viscous or gelled, clogging the nozzle tip, resulting in long This is because it tends to be difficult to perform stable spinning over time.

  In the spinning solution of the present invention, if it contains a coordination polymer, it may contain a polymer that does not coordinate bond with a metal ion (hereinafter sometimes referred to as “non-coordinating polymer”). good.

  The spinning solution of the present invention is obtained by dissolving the metal salt and the coordination polymer as described above in a solvent and coordinating them, and the solvent can dissolve the metal salt and the coordination polymer. If possible, water or an organic solvent can be used and is not particularly limited. However, when spinning a coordination bond fiber by an electrostatic spinning method, if the solvent contains an organic solvent (particularly composed of an organic solvent), the electrical conductivity of the spinning solution can be lowered and stabilized. And can be spun. In other words, in the case where a spinning solution prepared by dissolving a metal salt in water and mixing a predetermined amount of a polymer in the same manner as in the past is to be electrospun, the conductivity of the spinning solution is high and stable. However, if an organic solvent is included as a solvent in the spinning solution, the electrical conductivity of the spinning solution tends to be low, so that stable spinning can be performed by the electrostatic spinning method, and the spinning solution can be used for a long time. And stable spinning.

  The organic solvent is not particularly limited. For example, alcohols (for example, methanol, ethanol, propanol, etc.), dimethylformamide, dimethylacetamide, ketones (for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone) , Diacetone alcohol, etc.).

  As described above, the spinning solution of the present invention is obtained by dissolving and coordinating a metal salt and a coordination polymer. In addition to the coordination polymer, the spinning solution is capable of coordinating with metal ions of the metal salt. Molecular compounds (hereinafter sometimes referred to as “coordination compounds”) may also be dissolved. Such coordination compounds, like coordination polymers, can be coordinated with metal ions to stabilize the metal ions and prevent recrystallization of the metal ions without clogging the nozzle tip. , Stable spinning over a long period of time. In addition, the coordination bond between the metal ion and the coordination compound reduces the abundance ratio of free metal ions in the spinning solution and lowers the electrical conductivity of the spinning solution. Even when spinning, stable spinning is possible.

  Such a coordination compound is not particularly limited as long as it can be coordinate-bonded by giving a lone pair to the metal ion of the metal salt, but, like the above-described coordination polymer, As a donor atom, a coordination compound having a coordination group composed of O, S, N, or C can be used. More specifically, citric acid, ethyl lactate, ethyl acetoacetate and the like can be exemplified.

  The spinning solution of the present invention may contain metal oxide particles in addition to the coordination compound and non-coordination polymer as described above. The metal oxide particles may be an oxide of the metal or a composite oxide containing two or more kinds of the metals.

  In addition, in order to prepare the spinning solution of this invention, when dissolving a metal salt, a coordination polymer, and a coordination compound and / or a non-coordination polymer depending on the case, you may heat. The heating temperature is lower than the boiling point of the solvent and is a temperature at which the metal salt or the like dissolves. In the present invention, if no precipitate of metal salt, coordination polymer, coordination compound or non-coordination polymer is generated, it is considered “dissolved”.

  When two or more types of metal salt are dissolved, it is preferable to dissolve the metal salt at a molar ratio corresponding to the metal ratio in the metal oxide fiber to be produced.

  Furthermore, the amount of metal salt and the amount of coordination polymer are determined in consideration of the ratio between the amount of metal oxide and the amount of coordination polymer after firing because the concentration and the like vary depending on the type of metal salt and coordination polymer used. If the amount of coordination polymer is too large, it tends to shrink when fired or the metal oxide fiber tends to be porous. If the amount of coordination polymer is too small, recrystallization of metal ions is prevented. Since the spinnability tends to be poor, the mass ratio between the amount of metal oxide after firing and the coordination polymer is (the amount of metal oxide after firing) :( coordination polymer) = 1: 1. The metal salt and the coordination polymer are preferably blended so as to be 5, and (metal oxide amount after firing) :( coordination polymer) = 1: 2 to 4 It is more preferable to blend.

  Further, even when a coordination compound is contained, the mass ratio between the amount of the metal oxide after firing and the coordination polymer is within the above range so as to prevent recrystallization of metal ions and to have excellent spinnability. It is preferable to blend a metal salt and a coordination polymer.

  Furthermore, when it contains a non-coordinating polymer, it shrinks when fired, the metal oxide fiber is less likely to be porous, and recrystallization of metal ions is prevented, so that spinnability is excellent ( The amount of metal oxide after firing): (total amount of coordination polymer and non-coordinating polymer) = 1: 1-5, it is preferable to blend metal salt, coordination polymer and non-coordination polymer, More preferably, the metal salt, the coordination polymer, and the non-coordination polymer are blended so that the amount of metal oxide after firing): (total amount of coordination polymer and non-coordination polymer) = 1: 2-4.

  The mass ratio between the coordination polymer and the non-coordination polymer is not particularly limited, but (coordination polymer amount): (non-coordination polymer amount) so as not to inhibit the coordination action by the coordination polymer. = 1 to 5: 1 is preferable, and (coordinating polymer amount) :( non-coordinating polymer amount) = 1 to 3: 1 is more preferable.

  Moreover, when a coordination compound is included, it is preferable that the quantity is 1-2 equivalent with respect to a metal ion.

  The spinning solution of the present invention is a solution in which a metal salt and a coordination polymer are dissolved and a metal ion and a coordination polymer are coordinated and bonded, but the dissolution order is not particularly limited. For example, after dissolving the metal salt in the solvent, the coordination polymer may be dissolved, after dissolving the coordination polymer in the solvent, the metal salt may be dissolved, or the metal salt and the coordination polymer May be simultaneously dissolved in a solvent. Similarly, when dissolving a polymer other than the coordination polymer and / or the coordination compound, the dissolution order is not particularly limited.

  Next, the spinning solution prepared as described above is spun to form a coordinated bonded fiber in which metal ions and coordinated polymer are coordinated. This step is not particularly limited as long as the spinning solution prepared as described above can be spun to form a coordinated bonded fiber. For example, a conventional dry spinning method, an electrostatic spinning method, Method of spinning by gas shearing action as disclosed in JP2009-287138A, or gas shearing force in addition to the action of electric field as disclosed in JP2011-32593A And a method of spinning by acting. Among these, the electrospinning method is preferable because a coordination bond fiber having a small fiber diameter and a large surface area can be spun. If the spinning solution cannot be stably spun by the electrospinning method, for example, because the spinning solution has a high electrical conductivity, the spinning is performed by using the gas shearing action in addition to the electric field action or by the gas shearing action. According to the method, spinning can be stably performed.

  This preferred electrospinning method will be briefly described with reference to FIG. 1, which is a schematic side view of an apparatus capable of spinning fibers by the electrospinning method.

  The electrostatic spinning device in FIG. 1 is discharged from a spinning solution supply device 1 that can supply a spinning solution to a nozzle 2, a nozzle 2 that can discharge a spinning solution supplied from the spinning solution supply device 1, and a nozzle 2, and is stretched by an electric field. A voltage applying device 4 that can apply a voltage to the nozzle 2, a nozzle 2 and a collector so that an electric field can be formed between the grounded collector 3 and the nozzle 2 and the grounded collector 3. 3, a gas supply device 7 that can supply a gas having a predetermined relative humidity to the spinning vessel 6, and an exhaust device 8 that can exhaust the gas in the spinning vessel 6.

  In the case of such an electrostatic spinning device, the spinning solution is supplied to the nozzle 2 by the spinning solution supply device 1. The supplied spinning solution is discharged from the nozzle 2 and is subjected to a drawing action by an electric field formed between the grounded collector 3 and the nozzle 2 applied by the voltage application device 4 and is captured while being fiberized. Fly toward the assembly 3 (so-called electrostatic spinning method). The flying coordination binding fibers are directly accumulated on the collector 3.

  In addition, when coordinating the coordinated binding fibers continuously, the collector is moved and rotated in an oval shape in a direction orthogonal to the moving direction of the collector (the moving direction of the collector and the ellipse). It is preferable that the spinning solution is discharged from a group of nozzles whose major axes are perpendicular to each other, and the fiber-bonded coordination bonds are accumulated on the collector.

  Here, based on FIG. 2, which is a schematic side view of a spinning device that uses a gas shearing action in a case where spinning cannot be stably performed by an electrostatic spinning method, such as the electrical conductivity of the spinning solution is high, Briefly described.

  The spinning device of FIG. 2 supplies the spinning solution supply device 10 that can supply the spinning solution to the solution discharge nozzle 21, the solution discharge nozzle 21 that can discharge the spinning solution supplied from the spinning solution supply device 10, and the gas to the gas discharge nozzle 22. A gas supply nozzle 40 for spinning, a gas discharge nozzle 22 that can discharge the gas supplied from the gas supply apparatus 40 for spinning, and a discharge portion upstream of the solution discharge nozzle 21, and a voltage to the solution discharge nozzle 21. A voltage application device 90 that can be applied, is grounded, and sucks the gas discharged from the solution discharge nozzle 21 and collects the fiber-bonded coordination bond fibers, mainly the gas discharged from the gas discharge nozzle 22 Spinning that accommodates the suction device 50, the solution discharge nozzle 21, the gas discharge nozzle 22, the voltage application device 90, the collector 30, and the suction device 50. Vessel 60, is provided with an exhaust device 80 vessel gas supply apparatus 70 capable of supplying a gas having a predetermined relative humidity to the spinning container 60, and the gas in the spinning container 60 can be exhausted.

  When spinning a coordination bond fiber using such a spinning device, the spinning solution is supplied to the solution discharge nozzle 21 by the spinning solution supply device 10, and at the same time, the gas is discharged from the gas supply nozzle 40 by the spinning gas supply device 40. 22 is supplied. A voltage is applied to the solution discharge nozzle 21 by the voltage application device 90. Therefore, the spinning solution discharged from the solution discharge nozzle 21 is formed between the solution discharge nozzle 21 to which a voltage is applied and the grounded collector 30 in addition to the shearing action of the gas discharged from the gas discharge nozzle 22. The fiber is stretched by the action of the applied electric field, fiberized, becomes a coordination bond fiber and flies toward the collector 30. The flying coordination binding fibers are directly accumulated on the collector 30. In addition, since the gas discharged from the gas discharge nozzle 22 is mainly sucked by the suction device 50, the coordinated bonded fibers fly toward the collector 30 by the action of the electric field. The solution discharge nozzle 21, the gas discharge nozzle 22, and the like are housed in the spinning container 60, and the inside of the spinning container 60 is maintained at a predetermined relative humidity by the gas supplied by the container gas supply device 70. At the same time, the gas containing the solvent of the spinning solution volatilized during spinning is exhausted from the spinning container 60 by the exhaust device 80, and the spinning container 60 is maintained at the desired relative humidity. Spinning can be carried out stably.

  In addition, the coordination bond fiber does not need to be composed only of a compound in which a metal ion and a coordination polymer are coordinate-bonded, and the metal salt or the coordination polymer is not coordinate-bonded by blending the spinning solution, May exist.

  In addition, according to the spinning device of FIGS. 1 and 2, the coordinated binding fibers are accumulated in a sheet form, but other forms can be obtained by changing the shape of the collector. For example, if a rod-shaped collection body is used and the collection body is pulled out after collection, a hollow cylindrical shape can be obtained.

  And the process of manufacturing a metal oxide fiber is implemented by baking the coordination bond fiber spun as mentioned above. That is, since the coordination bond fiber spun as described above is in a state in which the metal ion and the coordination polymer are coordinated and bonded, in order to remove the coordination polymer and form the metal oxide fiber, in the presence of oxygen. Bake. In addition, baking can be implemented using oven, a sintering furnace, etc., for example, The temperature and time are suitably set with the metal oxide which comprises the metal oxide fiber obtained after baking.

The metal oxide fiber produced in this way is composed of one or more components. For example, it can be an oxide of a metal element as exemplified below.
(Metal elements) Lithium, beryllium, boron, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, Arsenic, selenium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, cadmium, indium, tin, antimony, tellurium, cesium, barium, lanthanum, hafnium, tantalum, tungsten, mercury, thallium, lead, bismuth, cerium, praseodymium, Neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium.

More _{specifically, SiO 2, Al 2 O 3} , B 2 O 3, TiO 2, ZrO 2, CeO 2, FeO, Fe 3 O 4, Fe 2 O 3, VO 2, V 2 O 5, SnO 2 _{, CdO, LiO 2, WO 3} , Nb 2 O 5, Ta 2 O 5, In 2 O 3, GeO 2, PbTi 4 O 9, LiNbO 3, BaTiO 3, PbZrO 3, KTaO 3, Li 2 B 4 O 7 NiFe ₂ O ₄ , SrTiO ₃ , Gd _0.1 Ce _0.9 O ₂ , Li _1.5 V ₃ O ₈ , LaCo _0.5 Ni _0.5 O ₃ , LaMnO _{3 and the} like.

  When the coordination bond fiber is spun by a method of applying an electric field such as an electrostatic spinning method, a thin metal oxide fiber having an average fiber diameter of 2 μm or less (preferably 1 μm or less) can be obtained.

  Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to these specific examples.

(Example 1) Production of Gd _0.1 Ce _0.9 O ₂ fiber (GDC fiber);
(1) After adding 100 g of 2-propanol to gadolinium nitrate hexahydrate (10 mmol) and cerium nitrate hexahydrate (90 mmol), the mixture is heated and stirred at a temperature of 80 ° C. for about 1 hour to dissolve the metal salt. A solution was obtained.
(2) by the lysate evaporator, _Gd 0.1 _Ce 0.9 _{O 2} when the _Gd 0.1 _Ce 0.9 _{O 2} is concentrated to a volume contained 30 wt% by burning, concentrated dissolved A liquid was obtained.
(3) Gd _0.1 Ce _0.9 O ₂ weight and methoxyethylene maleic anhydride when methoxyethylene maleic anhydride copolymer is baked to Gd _0.1 Ce _0.9 O _{2 in the} concentrated solution. The solution was dissolved so that the copolymer weight was 1: 3 to obtain a spinning solution.
(4) Using an electrospinning apparatus as shown in FIG. 1, the spinning solution was spun for 8 hours under the following conditions to obtain a coordinated bonded fiber. Spinning of this coordinated bonded fiber could be carried out stably without causing fiber fluff or nozzle clogging.
(Spinning conditions)
(A) Spinning fluid discharge rate: 0.5 g / hour (b) Applied voltage to nozzle: 7.5 kV
(C) Nozzle-drum distance: 10 cm
(D) Drum surface speed: 4.0 m / min.
(E) Supply air to the spinning container: temperature 25 ° C., humidity 25% RH
(5) The coordinating bond fiber was fired for 2 hours in a sintering furnace (in the air) set at a temperature of 600 ° C., and Gd _0.1 Ce _0.9 O ₂ fiber (average fiber diameter: 200 nm, see FIG. 3). ) Was manufactured.

(Example 2) Production of Gd _0.1 Ce _0.9 O ₂ fiber (GDC fiber);
In the same manner as in Example 1, after obtaining a concentrated solution, Gd ₀ when methoxyethylene maleic anhydride copolymer and polyvinylpyrrolidone were baked to Gd _0.1 Ce _0.9 O _{2 in} the concentrated solution. _.1 Ce _0.9 O ₂ weight, methoxyethylene maleic anhydride copolymer weight and polyvinylpyrrolidone weight were dissolved in a ratio of 1: 2: 1 to obtain a spinning solution.

Gd _0.1 Ce _0.9 O ₂ fibers (average fiber diameter: 200 nm, see FIG. 4) were produced in the same manner as in Example 1 except that this spinning solution was used. When spinning the coordination bond fiber, the fiber fuzz and nozzle clogging did not occur, and the coordination bond fiber could be spun stably.

Example 3 Production of Li _1.5 V ₃ O ₈ fiber;
(1) After adding 350 ml of water to ammonium metavanadate (V) and lithium acetate (20 mmol), the mixture was heated and stirred at a temperature of 80 ° C. for about 2 hours to dissolve the metal salt to obtain a solution. .
(2) A 40% citric acid solution was added to the solution until the pH of the solution became 3, and then the mixture was heated and stirred at a temperature of 80 ° C. for 2 hours to obtain an acidic solution.
(3) Ammonia water was added to the acidic solution until the pH reached 7 to obtain a neutral solution.
(4) the neutral lysate evaporator, _Li 1.5 _V 3 _{O 8} when a _Li 1.5 _V 3 _{O 8} by firing is concentrated to a volume contained 10 wt%, the concentrated solution Obtained.
(5) In the concentrated solution, Li _1.5 V ₃ O ₈ weight and methoxy ethylene maleic anhydride copolymer weight when methoxyethylene maleic anhydride copolymer is baked to Li _1.5 V ₃ O ₈ are obtained. The solution was dissolved so as to have a ratio of 1: 3 to obtain a spinning solution.
(6) Using an electrospinning apparatus capable of using an air shearing action as shown in FIG. 2, the spinning solution was spun for 8 hours under the following conditions to obtain coordination bonded fibers. Spinning of this coordinated bonded fiber could be carried out stably without causing fiber fluff or nozzle clogging.
(Spinning conditions)
(A) Spinning fluid discharge rate: 0.5 g / hour (B) Applied voltage to nozzle: 8.0 kV
(C) Nozzle-suction device distance: 10 cm
(D) Positional relationship between conveyor (collector) and suction device: conveyor and suction port are in contact (e) Conveyor moving speed: 4.0 m / min.
(F) Supply air to the spinning container: temperature 25 ° C., humidity 25% RH
(G) Gas discharge pressure: 0.3 MPa
(7) The coordination bond fiber is baked for 2 hours in a sintering furnace (in the air) set at a temperature of 450 ° C., and Li _1.5 V ₃ O ₈ fiber (average fiber diameter: 500 nm, see FIG. 5). Manufactured.

Comparative Example 1 Production of Gd _0.1 Ce _0.9 O ₂ fiber (GDC fiber);
In the same manner as in Example 1, after obtaining the concentrated solution, a polyvinylpyrrolidone concentration solution, fired by _Gd 0.1 _Ce 0.9 _{O 2} and the _Gd 0.1 _Ce 0.9 _{O 2} when The spinning solution was obtained by dissolving so that the weight of polyvinylpyrrolidone was 1: 2.

Next, using an electrostatic spinning apparatus as shown in FIG. 1, the spinning solution was spun under the following conditions to obtain mixed fibers. Although the mixed fibers could be spun, the mixed fibers were fluffed and the nozzles were clogged in a few minutes, making it difficult to spin. Furthermore, as can be understood from FIG. 6 (note that FIG. 6 is after firing), there were droplets on the fiber sheet, and stable spinning could not be performed.
(Spinning conditions)
(A) Spinning fluid discharge rate: 0.5 g / hour (B) Applied voltage to nozzle: 10.0 kV
(C) Nozzle-drum distance: 10 cm
(D) Drum rotation: None (fixed)
(E) Supply air to the spinning container: temperature 25 ° C., humidity 25% RH
Then, the mixed fibers were calcined for 2 hours with sintering furnace (atmosphere) set at a temperature 600 ° C. _and to produce a Gd _{0.1 Ce} 0.9 _{O 2} fibers (see FIG. 6).

(Comparative Example 2) Production of Gd _0.1 Ce _0.9 O ₂ fiber (GDC fiber);
(1) After adding 100 g of water to gadolinium nitrate hexahydrate (10 mmol) and cerium nitrate hexahydrate (90 mmol), the mixture is heated and stirred at a temperature of 80 ° C. for about 1 hour to dissolve and dissolve the metal salt. A liquid was obtained.
(2) by the lysate evaporator, _Gd 0.1 _Ce 0.9 _{O 2} when the _Gd 0.1 _Ce 0.9 _{O 2} is concentrated to a volume contained 30 wt% by burning, concentrated dissolved A liquid was obtained.
To (3) wherein the concentrated solution, polyvinylpyrrolidone, and _Gd 0.1 _Ce 0.9 _{O 2} by weight polyvinylpyrrolidone by weight when the _Gd 0.1 _Ce 0.9 _{O 2} by firing is 1: 2 A spinning solution was obtained by dissolving at a ratio.
(4) Using an electrostatic spinning apparatus as shown in FIG. 1, the spinning solution was spun under the following conditions to obtain mixed fibers. Although this mixed fiber could be spun, shots occurred and nozzle clogging occurred in a few minutes, making it difficult to spin. Further, there is a problem that the mixed fibers are re-dissolved.
(Spinning conditions)
(A) Spinning fluid discharge rate: 0.5 g / hour (B) Applied voltage to nozzle: 10.0 kV
(C) Nozzle-drum distance: 10 cm
(D) Drum rotation: None (fixed)
(E) Supply air to the spinning container: temperature 25 ° C., humidity 25% RH
(5) Although the mixed fiber was to be fired, the mixed fiber was not in a state where it could be fired and could not be fired.

  According to the production method of the present invention, even when the sol cannot be synthesized, the metal oxide fiber can be produced stably. The metal oxide fiber produced by the method of the present invention can be suitably used as a material constituting, for example, a filler, a catalyst carrier, an electrode material, a filter, and the like.

DESCRIPTION OF SYMBOLS 1, 10 Spinning liquid supply apparatus 2 Nozzle 21 Solution discharge nozzle 22 Gas discharge nozzle 3, 30 Collecting body 4, 90 Voltage application apparatus 6, 60 Spinning container 7 Gas supply apparatus 8, 80 Exhaust apparatus 40 Gas supply apparatus for spinning 50 Suction Device 70 Gas supply device for containers

Claims (1)

Preparing a spinning solution in which a metal salt and a maleic anhydride-based polymer capable of coordinating with a metal ion of the metal salt are dissolved;
A step of spinning the spinning solution to form coordination bond fibers, and a step of producing metal oxide fibers by firing the coordination bond fibers.
A method for producing a metal oxide fiber.

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