JP2004183133A - Method for producing inorganic fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing inorganic fibers uniform in fiber length and scarcely forming shots (flaked films and/or particulate matters). <P>SOLUTION: The method for producing the inorganic fibers comprises (1) the step of preparing a sol solution consisting mainly of an inorganic component, (2) the step of extruding the sol solution via a nozzle, subjecting the extruded sol solution to an electric field to form inorganic gel-like fibers, (3) the step of subjecting the inorganic gel-like fibers to a gas prior to accumulating the inorganic gel-like fibers, (4) the step of accumulating the resultant inorganic gel-like fibers on a trapping member, and (5) the step of drying the thus trapped inorganic gel-like fibers to form dry inorganic gel-like fibers as the final inorganic fibers, and preferably furthermore, the step of sintering the (dry) inorganic gel-like fibers to form sintered inorganic fibers as the final inorganic fibers. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an inorganic fiber.
[0002]
[Prior art]
For example, an inorganic fiber sheet made of an inorganic fiber (for example, glass fiber) is excellent in filtration performance, separation performance, and the like, and is therefore suitably used as a filter material, a separator for a lead storage battery, and the like.
[0003]
The inorganic fibers constituting such an inorganic fiber sheet have been manufactured by a blow method or a centrifugal method. In other words, the former blowing method is a method of injecting gas into the extruded melt to fibrillate the melt to produce inorganic fibers (for example, Japanese Patent Publication No. 37-7925), and the latter method. Is a method in which a molten ceramic composition is supplied to a high-speed rotating plate, and the molten ceramic composition is fiberized by centrifugal force caused by high-speed rotation of the high-speed rotating plate (for example, JP-A-53-38719). It is. However, using any of these methods, the thickness of the resulting fiber is not uniform, and non-fibrous materials (so-called shots) such as flake-like films and grains are easily generated.
[0004]
[Patent Document 1]
JP-B-37-7925 (Claims)
[Patent Document 2]
JP-A-53-38719 (Claims)
[0005]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems, and has as its object to provide a method for producing an inorganic fiber having a uniform fiber thickness and less occurrence of shots.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is directed to “(1) a step of forming a sol solution mainly composed of an inorganic component, (2) extruding the sol solution from a nozzle and applying an electric field to the extruded sol solution. (3) a step of applying a gas to the inorganic gel fiber before accumulation, and (4) a step of applying a gas to the inorganic gel fiber that has been subjected to the gas. A process for accumulating on a collecting member, and (5) a step of drying the gaseous inorganic gel fiber to form an inorganic dry gel fiber, '' It is. When an electric field is applied to the sol solution extruded from the nozzle in this manner, the fibers have a uniform thickness and are unlikely to generate shots. Was found to be able to produce an inorganic fiber in which the fibers are not adhered, the fibers are not adhered to each other, and the individual fibers are in an independent state.
[0007]
The invention according to claim 2 of the present invention is characterized by further comprising a step of sintering the gas-acting inorganic gel fiber or the inorganic dry gel fiber to form an inorganic sintered fiber. The method for producing an inorganic fiber according to claim 1 ". According to this method, in addition to the same functions and effects as the first aspect, sintered inorganic fibers can be manufactured.
[0008]
The invention according to claim 3 of the present invention is “the method for producing an inorganic fiber according to claim 1 or 2, wherein the temperature of the gas is 40 ° C. or less”. When the temperature of the gas is 40 ° C. or lower, the adhesion between the inorganic fibers can be efficiently prevented.
[0009]
The invention according to claim 4 of the present invention relates to "the method for producing an inorganic fiber according to any one of claims 1 to 3, wherein the relative humidity of the gas is 55% or less." is there. As described above, when the relative humidity is 55% or less, the gas-acting inorganic gel fibers can be dried to some extent, so that non-bonded inorganic fibers can be efficiently produced.
[0010]
The invention according to claim 5 of the present invention is characterized in that the gas-acting inorganic gel fibers are accumulated in a collecting member located in a direction different from the direction of the electric field. 4. The method for producing an inorganic fiber according to any one of 4. By accumulating on the collecting member located in this way, the collision force between the gas-acting inorganic gel fibers can be reduced, so that non-bonded inorganic fibers can be efficiently produced.
[0011]
The invention according to claim 6 of the present invention provides a method for producing an inorganic fiber according to any one of claims 1 to 5, wherein the collection member is made of a non-conductive material. Method ". As described above, since the collecting member is formed of the non-conductive material, and the gas-acting inorganic gel fibers do not directly accumulate on the collecting member, the adhesion between the gas-acting inorganic gel fibers is effectively prevented. At the same time, they can be collected efficiently.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the method for producing an inorganic fiber of the present invention, first, (1) a step of forming a sol solution mainly containing an inorganic component is performed. In the present specification, "mainly composed of an inorganic component" means that the inorganic component occupies 50 mass% or more, more preferably occupies 60 mass% or more, and occupies 75 mass% or more. Is more preferred.
[0013]
This sol solution is an inorganic fiber finally obtained by the production method of the present invention, a solution (raw material solution) containing a compound containing an element constituting an inorganic dry gel fiber or an inorganic sintered fiber, It can be obtained by hydrolysis at a temperature of about 100 ° C. or less and condensation polymerization. The solvent of the raw material solution is, for example, an organic solvent (eg, alcohol) or water.
[0014]
Although the elements constituting this compound are 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, Mention may be made of potassium, ytterbium, lutetium or the like.
[0015]
Examples of the compound include oxides of the above-mentioned elements, and 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 and the} like. The inorganic component may be composed of one component oxide or two or more components oxide. For example, it can be composed of _two components of SiO ₂ —Al ₂ O ₃ .
[0016]
The sol solution is obtained by subjecting the raw material solution to a process of subjecting the compound to polycondensation, and is mainly composed of an inorganic component. That is, the inorganic component occupies 50 mass% or more, preferably 60 mass% or more, and more preferably 75 mass% or more.
[0017]
The sol solution needs to have a viscosity that allows spinning from a nozzle in a fiber forming step described below. The viscosity is not particularly limited as long as it is a spinnable viscosity, but is preferably 0.1 to 100 poise, more preferably 0.5 to 20 poise, particularly preferably 1 to 10 poise, and most preferably. 1-5 poise. If the viscosity exceeds 100 poise, it becomes difficult to reduce the fiber size, and if the viscosity is less than 0.1 poise, the fiber shape tends not to be obtained. When the atmosphere at the tip of the nozzle is a solvent gas atmosphere similar to the raw material solution, spinning may be possible even with a sol solution exceeding 100 poise.
[0018]
The sol solution of the present invention can contain, in addition to the inorganic components described above, an organic component, such as a silane coupling agent, an organic low-molecular compound such as a dye, and polymethyl methacrylate. And organic polymer compounds of the above. More specifically, when the compound contained in the raw material solution is a silane-based compound, it may include a condensation-polymerized silane-based compound organically modified with a methyl group or an epoxy group.
[0019]
The raw material solution is a solvent for stabilizing a compound contained in the raw material solution (for example, an organic solvent (for example, alcohols such as ethanol, dimethylformamide) or water), and for hydrolyzing a compound contained in the raw material solution. Of water and a catalyst (for example, hydrochloric acid, nitric acid, etc.) that allows the hydrolysis reaction to proceed smoothly. Also, contained in the raw material solution, for example, a chelating agent for stabilizing a compound, a silane coupling agent for stabilizing the compound, a compound capable of imparting various functions such as piezoelectricity, improving adhesion, An organic compound (for example, polymethyl methacrylate) for adjusting flexibility and hardness (fragility) or an additive such as a dye can be contained. These additives can be added before, during or after the hydrolysis.
[0020]
Further, the raw material solution may include inorganic or organic fine particles. Examples of the inorganic fine particles include titanium oxide, manganese dioxide, copper oxide, silicon dioxide, activated carbon, and metal (for example, platinum). Examples of the organic fine particles include a dye or a pigment. The average particle size of the fine particles is not particularly limited, but is preferably 0.001 to 1 μm, more preferably 0.002 to 0.1 μm. By containing such fine particles, an optical function, porosity, catalytic function, adsorption function, ion exchange function, or the like can be provided.
[0021]
In the case of tetraethoxysilane, if the amount of water exceeds 4 times (molar ratio) the alkoxide, it becomes difficult to obtain a spinnable sol solution, and therefore it is preferably 4 times or less the alkoxide.
[0022]
When a base is used as a catalyst, it is difficult to obtain a spinnable sol solution, and therefore, it is preferable not to use a base.
[0023]
The reaction temperature may be lower than the boiling point of the solvent used, but the lower the reaction temperature is, the slower the reaction speed is, and the easier it is to form a spinnable sol solution. If the temperature is too low, the reaction does not easily proceed.
[0024]
Next, in the present invention, (2) a step of extruding the sol solution from a nozzle and forming a fiber by applying an electric field to the extruded sol solution to form inorganic gel fibers.
[0025]
The direction of extrusion of the sol solution is not particularly limited, but it is preferable that the direction of extrusion from the nozzle does not coincide with the direction of action of gravity so that dripping of the sol solution is unlikely to occur. In particular, it is preferable to extrude the sol solution in a direction opposite to the direction of action of gravity or in a direction perpendicular to the direction of action of gravity.
[0026]
The diameter of the nozzle that pushes out the sol solution varies depending on the fiber diameter of the inorganic fibers (that is, the inorganic dry gel fibers or the inorganic sintered fibers). For example, when the fiber diameter of the inorganic fiber is 2 μm or less, the diameter of the nozzle is preferably about 0.1 to 3 mm.
[0027]
Further, the nozzle may be made of metal or non-metal. When the nozzle is made of metal, the nozzle can be used as one electrode. When the nozzle is made of nonmetal, an electric field can be applied to the extruded sol solution by installing an electrode in the nozzle. Can be.
[0028]
After the sol solution is extruded from such a nozzle, the extrudate is stretched by applying an electric field to the extrudate to form an inorganic gel fiber. This electric field varies depending on the fiber diameter of the target inorganic fiber (inorganic dry gel fiber or inorganic sintered fiber), the distance between the nozzle and the counter electrode, the solvent of the raw material solution, the viscosity of the sol solution, and the like. Although not particularly limited, for example, when the fiber diameter of the inorganic fiber (inorganic dry gel fiber or inorganic sintered fiber) is about 3 μm or less, it is 0.5 to 5 kV / cm. Is preferred. If the electric field to be applied is large, the fiber diameter of the inorganic gel fiber becomes thinner according to the increase of the electric field value, and at the same time, the amount of the sol solution that can be stably extruded from the nozzle increases. If it exceeds, the dielectric breakdown of air easily occurs, which is not preferable. On the other hand, when it is less than 0.5 kV / cm, it is difficult to form a fiber.
[0029]
When an electric field is applied, an electrostatic charge is accumulated in the sol solution, and the sol solution is electrically pulled by the counter electrode, stretched, and fiberized. In particular, since the fibers are electrically stretched, as the inorganic gel fibers approach the support, the speed of the fibers is accelerated and the fibers become thinner.
[0030]
Such an electric field can be exerted by, for example, providing a potential difference between the nozzle (the nozzle itself in the case of a metal nozzle and the electrode in the nozzle in the case of a non-metal nozzle) and the counter electrode. it can. For example, a potential difference can be provided by applying a voltage to the nozzle and grounding the counter electrode, or conversely, a potential difference can be provided by applying a voltage to the counter electrode and grounding the nozzle.
[0031]
Next, in the present invention, (3) a step of causing a gas to act on the inorganic gel fibers before accumulation is performed. In this step, by changing the moving direction of the inorganic gel-like fibers, the impact force between the gas-active inorganic gel-like fibers at the time of accumulation is reduced, and the meaning of preventing the adhesion between the gas-active inorganic gel-like fibers, By drying the inorganic gel fibers to some extent, there is at least one of the meanings of preventing the adhesion of the gas-acting inorganic gel fibers to each other, and in any case, the object of the present invention is that the fibers are bonded to each other. This is a necessary step for producing inorganic fibers which are independent fibers. When a gas is applied to the inorganic gel-like fiber, the inorganic gel-like fiber becomes thinner due to the evaporation of the solvent, and the static electricity density is increased. It is considered to be an inorganic gel fiber.
[0032]
The gas to be acted on may be any gas that can act on the inorganic gel fiber, and is not particularly limited, but air is preferably used for production. In addition, when the temperature of the gas is 40 ° C. or less, or when the relative humidity of the gas is 55% or less, the inorganic gel fiber can be dried. This is preferable because the adhesion between the acting inorganic gel fibers is effectively prevented, and the individual gas acting inorganic gel fibers are easily accumulated in an independent state. Note that a more preferable relative humidity is 40% or less. The lower limit of the relative humidity is 0%.
[0033]
The direction in which the gas acts may be the same direction as the electric field operation direction (the direction connecting the nozzle to the counter electrode) or may be a different direction, but it is the same as the electric field effect as the former. Due to both the electrostatic force and the physical force of the gas, the gaseous inorganic gel fibers strongly collide with the collecting member, and the possibility of bonding the gaseous inorganic gel fibers to each other is high. Therefore, it is preferable that the direction in which the gas acts is different from the direction in which the electric field acts so that the individual gas-acting inorganic gel fibers can be easily accumulated individually. From the viewpoint that the stretching action by the electric field can be minimized, the gas is preferably acted on at right angles to the direction in which the electric field acts.
[0034]
As a method of causing a gas to act on the inorganic gel fibers, for example, there is a method of ejecting a gas from a gas discharge nozzle. In the case where the gas is actuated in this way, it is preferable to use a gas discharge nozzle capable of ejecting the gas straight to some extent so that the inorganic gel fiber does not diffuse much. As such a gas discharge nozzle, a flat air nozzle (for example, a nozzle having a narrow discharge portion) can be given.
[0035]
Further, such a gas discharge nozzle is preferably made of a non-conductive material. If the gas discharge nozzle is made of a conductive material, an electric field is formed between the gas discharge nozzle and the nozzle that pushes out the sol solution, and the inorganic gel fibers may accumulate in the gas discharge nozzle. . The term “non-conductive” in the present invention refers to those having an electric resistance (volume specific resistance) of 10 ¹² Ω or more. When the gas discharge nozzle is made of a conductive material, the gas discharge nozzle is preferably electrically isolated.
[0036]
Next, in the present invention, (4) a step of accumulating the gas-operated inorganic gel-like fibers with gas acting on the collecting member is performed.
[0037]
The collection member is not particularly limited, and examples thereof include a gas suction nozzle and a gas-permeable support. When the gas suction nozzle is used as in the former case, depending on the amount of gas suction, the fibers may adhere to each other due to the collision of the gas-acting inorganic gel-like fibers. It is preferred to use a gas suction nozzle of the formula. Also, in the case where the suction device is not provided, as in the case of the latter air-permeable support, the gas is accumulated by the flow of the gas from the gas discharge nozzle as described above, and the gas flows in a gentle flow. The action inorganic gel fibers are to be accumulated, but since the gas action inorganic gel fibers are charged to the same polarity, they must be accumulated in a state where the fibers are not easily bonded to each other due to the repulsive force between the fibers. Can be.
[0038]
Such a trapping member may be located in the same direction as the electric field action direction or in a different direction. However, as described above, the gas acts in a direction different from the electric field action direction. Therefore, it is preferable that the collecting member is also located in a direction different from the electric field action direction, and the gas action inorganic gel fibers are accumulated. By being located in this manner, it becomes easy to avoid the adhesion between the gas-acting inorganic gel fibers. In addition, it is preferable that the collecting member is positioned in a direction perpendicular to the direction of the electric field, because the stretching action by the electric field can be minimized.
[0039]
In addition, it is preferable that the above-described collection member is also made of a non-conductive material. When the collecting member is made of a conductive material, an electric field is formed between the collecting member and the nozzle that pushes out the sol solution, and the gaseous inorganic gel fibers are directly accumulated on the collecting member, and the fibers are separated from each other. This is because the adhesion of the particles easily occurs. When the collection member is made of a conductive material, the collection member is preferably electrically isolated.
[0040]
Further, the speed at which the gas passes through the collection member is not particularly limited, but is set to 1000 cm / sec. So as to easily avoid the adhesion between the gas-acting inorganic gel fibers. It is preferably 100 cm / sec. It is more preferable that: Further, in order to prevent the accumulated gaseous inorganic gel fibers from scattering, 10 cm / sec. The above is preferable.
[0041]
Next, (5) a step of drying the gaseous inorganic gel fiber to form an inorganic dry gel fiber is performed to produce a handleable inorganic dry gel fiber, that is, an inorganic fiber.
[0042]
This drying temperature is not particularly limited because it varies depending on the inorganic component constituting the gas-acting inorganic gel fiber, but the drying temperature is lower than the decomposition temperature of the organic component, for example, at a temperature of about 200 ° C. or less. Is preferred. This drying can be carried out by heating in an oven or the like, and can also be carried out by freeze drying or supercritical drying. In this drying step, drying is performed until necessary handling strength is obtained.
[0043]
The above is a method for producing an inorganic dry gel fiber (inorganic fiber). In the case of producing an inorganic sintered fiber (inorganic fiber), a step of further sintering the inorganic dry gel fiber. Is carried out. By performing the sintering step, an inorganic sintered fiber having excellent strength and heat resistance can be manufactured. The sintering step can be performed using, for example, a sintering furnace, and the temperature is appropriately set according to the inorganic components constituting the inorganic dry gel fiber. For example, when the inorganic dry gel fiber is made of a silica component, sintering at a temperature of 800 ° C. or more can produce a sintered silica fiber.
[0044]
In addition, the inorganic sintered fiber can be produced not only by sintering the inorganic dry gel fiber, but also by directly sintering the gaseous inorganic gel fiber without drying. Can be. In this case, if the sintering is performed at the sintering temperature, the gaseous inorganic gel fiber may suddenly shrink and be damaged. .
[0045]
In addition, the inorganic fiber (inorganic dry gel fiber or inorganic sintered fiber) thus produced is basically a continuous fiber, but if necessary, the inorganic fiber is cut. Alternatively, the fibers can be crushed into short fibers.
[0046]
The method for producing an inorganic fiber of the present invention will be described with reference to FIG. 1 which is a conceptual diagram of an apparatus capable of producing an inorganic fiber.
[0047]
First, the sol solution prepared as described above is supplied to the metal nozzle 1 from a sol solution storage unit (not shown) by a metering pump or the like (not shown). The supply amount to the nozzle 1 is not particularly limited, but can be changed in a range of 0.01 mL / hour to 100 mL / hour per nozzle. In FIG. 1, one nozzle is provided, but two or more nozzles may be provided.
[0048]
The sol solution thus supplied to the nozzle 1 is extruded from the nozzle 1. On the other hand, since a voltage is applied to the nozzle 1 and the counter electrode 2 is grounded, an electric field is formed between the nozzle 1 and the counter electrode 2, and the sol solution extruded by the electric field is stretched. The fibers are formed into fibers and inorganic gel fibers are formed. The position of the nozzle 1 is set so that the distance between the nozzle 1 and the counter electrode 2 can be set to about 10 to 500 mm, preferably about 50 to 300 mm so that the electric field strength can be adjusted to 0.5 to 5 kV / cm. Preferably, it can be changed. In addition, contrary to the above method, the nozzle 1 may be grounded and a voltage may be applied to the counter electrode 2.
[0049]
The inorganic gel fiber formed by stretching the sol solution extruded from the nozzle 1 is attracted to the counter electrode 2 by the action of the electric field, and is directed in the direction perpendicular to the electric field action direction D on the way to the counter electrode 2. By changing the course in the direction perpendicular to the electric field action direction D by the action of the gas discharged from the gas discharge nozzle 3 located at the position, the nozzle moves. At this time, the inorganic gel fibers become gaseous inorganic gel fibers which are dried to some extent by the action of gas. In FIG. 1, the gas is ejected in the direction perpendicular to the electric field action direction D to act, but the gas does not need to be orthogonal.
[0050]
The gas-acting inorganic gel fibers formed as described above move along with the flow of the gas and are collected by the collecting member 4 installed at a position facing the gas discharge nozzle 3. In FIG. 1, the side surface of the gas discharge nozzle is open, and a rectangular parallelepiped collecting member 4 whose surface facing the side surface of the gas discharge nozzle is made of a gas-permeable material is used. In addition, the collecting member 4 has a surface made of a gas-permeable material connected to the exhaust fan 5 via a duct, and can appropriately suck the gas. Therefore, scattering of the accumulated gaseous inorganic gel fibers can be prevented. It has become.
[0051]
The gas-action inorganic gel fibers thus accumulated are supplied to a heater (not shown) after a desired accumulation amount, and dried by the heat of the heater to become inorganic dry gel fibers. Alternatively, the accumulated gaseous inorganic gel fibers are supplied to a sintering furnace (for example, an electric furnace) after a desired accumulation amount, and are sintered by the heat of the sintering furnace. It becomes. In some cases, the inorganic dry gel fiber is supplied to a sintering furnace and sintered.
[0052]
Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.
[0053]
【Example】
(Example 1)
(1) Formation of Sol Solution Tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and 1N hydrochloric acid as a catalyst are mixed in a molar ratio of 1: 5: 2: 0.003, The mixture was refluxed at a temperature of 78 ° C. for 10 hours, then the solvent was removed by a rotary evaporator and concentrated, and then heated to a temperature of 60 ° C. to form a sol solution having a viscosity of 2 poise.
[0054]
(2) The sol solution is supplied to one stainless steel nozzle (inner diameter: 0.6 mm) by a pump for forming an inorganic gel fiber, and the nozzle is supplied at a rate of 1 mL / hour in a direction opposite to the direction of gravity. While applying a voltage of −20 kV to the nozzle, and grounding a counter electrode located 10 cm away from the nozzle to form an inorganic gel fiber toward the counter electrode.
[0055]
(3) Formation of gaseous inorganic gel-like fiber With respect to the flow of the inorganic gel-like fiber (the direction of electric field action), air (temperature: 25) is fed from a polypropylene flat air nozzle arranged at right angles to the direction of electric field action. ° C, relative humidity: 20%) when the air velocity across the inorganic gel-like fiber moving point is 100 cm / sec. Then, a gas was applied to the inorganic-based gel-like fiber to partially dry it to form a gas-operated inorganic-type gel-like fiber, and at the same time, the flow was changed in a direction perpendicular to the direction of the electric field.
[0056]
(4) Accumulation of gaseous inorganic gel fibers The gaseous inorganic gel fibers are accumulated by a gas-permeable collecting member disposed at a position facing the flat air nozzle (in a direction perpendicular to the direction of electric field action). . In addition, as a breathable collection member, the outer shape is a rectangular parallelepiped, and the entrance side surface of the gaseous inorganic gel fiber is open, and this surface has a square shape of 20 cm on a side, and the entrance side The exit surface facing the surface was made of a 60 mesh polypropylene net. Further, the air-permeable collecting member is connected to an exhaust fan, and the air flow in the air-permeable collecting member is about 10 cm / sec. Suction was performed from the outlet side of the air-permeable collection member so that
[0057]
(5) Formation of inorganic dry gel-like fiber The gas-action inorganic gel-like fiber thus collected is dried by a heater set at a temperature of 150 ° C. to obtain an inorganic dry gel-like fiber (consisting of SiO ₂ ). Manufactured. This inorganic dry gel fiber corresponded to about 70% of the mass extruded from the nozzle, and the bulk of 1 g of the inorganic dry gel fiber was about 150 mL. Further, almost no adhesion between the inorganic dry gel fibers was observed. Further, no impurities such as flakes and shots were observed.
[0058]
(6) Formation of Sintered Silica Fiber The dried inorganic fiber gel was sintered at a temperature of 800 ° C. to produce a sintered silica fiber. The average fiber diameter (the arithmetic mean value of the fiber diameter at 100 points) of the sintered silica fiber is 0.6 μm, the CV value of the fiber diameter (= standard deviation / average fiber diameter) is as thin as 0.4, and Was uniform in thickness.
[0059]
(Example 2)
(4) The wind speed in the air-permeable collecting member is 20 cm / sec. Thus, an inorganic dry gel-like fiber was produced in exactly the same manner as in Example 1 except that suction was performed by an exhaust fan.
[0060]
The inorganic dry gel fibers corresponded to about 70% of the mass extruded from the nozzle, and the volume of 1 g of the inorganic dry gel fibers was about 100 mL. Further, almost no adhesion between the inorganic dry gel fibers was observed. Further, no impurities such as flakes and shots were observed.
[0061]
Next, the inorganic dry gel fiber was sintered in the same manner as in Example 1 to produce a sintered silica fiber. The average fiber diameter (the arithmetic mean value of the fiber diameter at 100 points) of this silica sintered fiber is 0.6 μm, the CV value of the fiber diameter (= standard deviation / average fiber diameter) is as thin as 0.4, and Was uniform in thickness.
[0062]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the manufacturing method of the inorganic fiber of this invention, the thickness of a fiber is uniform, and an inorganic fiber can be manufactured, without producing a shot.
[0063]
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an apparatus capable of producing the inorganic fiber of the present invention.
DESCRIPTION OF SYMBOLS 1 Nozzle 2 Counter electrode 3 Gas discharge nozzle 4 Collection member 5 Exhaust fan

Claims (6)

(1) a step of forming a sol solution mainly composed of an inorganic component,
(2) a step of extruding the sol solution from a nozzle and applying an electric field to the extruded sol solution to form fibers to form inorganic gel fibers;
(3) a step of causing a gas to act on the inorganic gel fibers before accumulation;
(4) a step of accumulating the gas-acting inorganic gel-like fibers with gas acting on the collecting member;
(5) drying the gaseous inorganic gel fiber to form an inorganic dry gel fiber;
And a method for producing an inorganic fiber. The method of claim 1, further comprising sintering the gaseous inorganic gel fiber or the inorganic dry gel fiber to form an inorganic sintered fiber. Method. The method according to claim 1, wherein the temperature of the gas is 40 ° C. or less. The method for producing an inorganic fiber according to any one of claims 1 to 3, wherein the relative humidity of the gas is 55% or less. The production of the inorganic fibers according to any one of claims 1 to 4, wherein the gaseous inorganic gel fibers are accumulated on a collecting member located in a direction different from the electric field action direction. Method. The method for producing an inorganic fiber according to any one of claims 1 to 5, wherein the collection member is made of a non-conductive material.

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