JP3963439B2 - Inorganic structure manufacturing method and inorganic structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an inorganic structure made of inorganic fine fibers or mainly composed of inorganic fine fibers. Furthermore, this invention relates to the inorganic structure which can be manufactured with the said manufacturing method, consists of an inorganic type | system | group extra long elongate fiber, or consists mainly of an inorganic type extra long elongate fiber.
[0002]
[Prior art]
For example, an inorganic short fiber sheet made of inorganic short fibers (for example, glass short fibers) is excellent in filtration performance, separation performance, and the like, and thus is suitably used as a filter material or a separator for a lead storage battery. .
Such an inorganic short fiber sheet has been produced, for example, by forming inorganic short fibers into a sheet by a wet method. In the inorganic short fiber sheet thus produced, the inorganic short fibers constituting the inorganic short fiber sheet may drop off. Therefore, it is preferable to bond the inorganic short fibers with an adhesive. However, when the adhesive is used, there is a problem that the adhesive is eluted or the use of the inorganic short fiber sheet is limited depending on the kind of the adhesive.
[0003]
Regarding inorganic short fibers, for example, “Sol-Gel Science” (Sakuo Sakuhana, Agne Jofusha, July 5, 1988) has short fibers with a diameter of 10 μm and a maximum length of 20 mm. It is described that it is obtained (pages 78-79). However, in the case of a fiber sheet manufactured from such a short fiber, there is a risk of fiber dropping because of the short fiber. If an adhesive is used to prevent this, elution of the adhesive and applications are limited. There was a problem.
For example, when an inorganic short fiber sheet is used as a filter for a clean room filter, there is a possibility that an eluate from the adhesive may adhere to the surface of a silicon wafer or a glass substrate, or the inorganic short fiber sheet is heat resistant. When used as a filter material for a filter, the adhesive has no heat resistance and may not be used.
Moreover, since such an inorganic short fiber has a large fiber diameter and is not flexible, its shape is limited to a sheet shape or a flat plate shape.
[0004]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to eliminate the drawbacks of the prior art, and specifically, a method for producing an inorganic structure that can prevent the adverse effects of using an adhesive. Is to provide. Furthermore, an object of the present invention is to provide an inorganic structure having low flexibility and excellent flexibility, and to provide an inorganic structure that hardly generates contaminants from an adhesive.
[0005]
[Means for Solving the Problems]
  The above problems are solved by the present invention.
(1) a step of forming a sol solution mainly composed of an inorganic component (hereinafter sometimes referred to as a sol solution forming step);
(2) The sol solution is extruded from a nozzle, and is thinned by applying an electric field to the extruded sol solution to form inorganic gel fine fibers, and the inorganic gel fine fibers are accumulated on the support. A process (hereinafter sometimes referred to as an accumulation process), and
(3) Drying the accumulated inorganic gel-like fine fibers to form an inorganic structure containing inorganic dry gel-like fine fibers (hereinafter sometimes referred to as a drying step), and / or A step of sintering the accumulated inorganic gel fine fibers to form an inorganic structure including inorganic sintered fine fibers (hereinafter sometimes referred to as a sintering step).
It can solve by the manufacturing method of an inorganic type structure characterized by including this.
  According to such a production method of the present invention, an inorganic structure can be produced without using an adhesive by drying and / or sintering. Can be prevented.
  According to a preferred embodiment of the production method of the present invention, before the inorganic gel-like fine fibers reduced in diameter by applying an electric field are accumulated on the support, Threads made of fiber, inorganic fiber, organic fiber and / or inorganic fiber, or powder can be sprayed.
  Of the production method of the present inventionanotherAccording to a preferred embodiment, the support used in the accumulation step (2) has a three-dimensional solid shape. Since the inorganic structure thus obtained has a three-dimensional solid shape, it can be adapted to various uses.
[0006]
  Furthermore, the present invention relates to an inorganic structure having an average fiber diameter of 2 μm or less and containing inorganic ultrafine fibers mainly composed of inorganic components.
  Since the inorganic structure of the present invention is made of long fibers, the possibility of dropping off the fibers is low, and the average fiber diameter is very thin, 2 μm or less, and it has excellent flexibility, so it can be deformed into various shapes. It can be applied to various uses.
  In a preferred embodiment of the inorganic structure of the present invention, the inorganic extra-fine long fibers are bonded at the contact points without using an adhesive. Moreover, in the preferable aspect of the inorganic type structure of this invention, the adhesive agent is not included substantially. Such an inorganic structure does not easily generate contaminants from the adhesive because no adhesive is present.
  In another preferred embodiment of the inorganic structural body of the present invention, the CV value (= standard deviation / average fiber diameter) of the fiber diameter of the inorganic ultrafine fiber is 0.8 or less. Such an inorganic structure is preferable because the performance becomes uniform.
  In still another preferred embodiment of the inorganic structure according to the present invention, the inorganic extra-fine fibers include organic fibers, thick inorganic fibers having a fiber diameter exceeding 2 μm, inorganic short fibers, and organic fibers. And yarn, woven fabric, knitted fabric, non-woven fabric, net, or powder composed of one or more fibers selected from the group consisting of inorganic fibers having a fiber diameter exceeding 2 μm and inorganic short fibers, It is included in a compound state.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the production method of the present invention, first, the sol solution forming step (1) is performed. That is, a sol solution mainly composed of inorganic components is formed. In this specification, “mainly composed of an inorganic component” means that the inorganic component occupies 50% by mass or more. The inorganic component content of the sol solution is preferably 60% by mass or more, and more preferably 75% by mass or more.
This sol solution is a solution (raw material solution) containing a compound containing an element constituting an inorganic dry gel-like fine fiber or an inorganic sintered fine fiber constituting an inorganic structure finally obtained by the production method of the present invention. ) Can be obtained by hydrolyzing at a temperature of about 100 ° C. or less, followed by condensation polymerization. The solvent of the raw material solution is, for example, an organic solvent (for example, alcohol) or water.
[0008]
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.
[0009]
  Examples of the compound include oxides of the elements, specifically, SiO.₂, Al₂O_Three, B₂O_ThreeTiO₂, ZrO₂, CeO₂, FeO, Fe_ThreeO_Four, Fe₂O_Three, VO₂, V₂O_Five, SnO₂, CdO, LiO₂, WO_Three, Nb₂O_Five, Ta₂O_Five, In₂O_Three, GeO₂, PbTi_FourO₉LiNbO_Three, BaTiO_Three, PbZrO_Three, KTaO_Three, Li₂B_FourO₇NiFe₂O_Four, SrTiO_ThreeAnd so on. The inorganic component may be composed of one component oxide or may be composed of two or more component oxides. For example, SiO₂-Al₂O_ThreeoftwoIt can consist of components.
[0010]
The sol solution is obtained by subjecting the raw material solution to a polycondensation treatment of the compound, and is mainly composed of an inorganic component. That is, the inorganic component accounts for 50% by mass or more, preferably 60% by mass or more, more preferably 75% by mass or more. The sol solution needs to have a viscosity that enables spinning from a nozzle in an accumulation step (2) described later. 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. Is 1-5 poise. When the viscosity exceeds 100 poise, it is difficult to make fine fibers, and when the viscosity is less than 0.1 poise, the fiber shape cannot be obtained. If the atmosphere at the nozzle tip is the same solvent gas atmosphere as the raw material solution, spinning may be possible even with a sol solution exceeding 100 poise.
The sol solution used in the method of the present invention can contain an organic component in addition to the inorganic component as described above. Examples of the organic component include organic low-molecular compounds such as silane coupling agents and dyes, polymethyl And organic polymer compounds such as methacrylate. More specifically, when the compound contained in the raw material solution is a silane compound, it can contain a polycondensation of a silane compound organically modified with a methyl group or an epoxy group.
[0011]
The raw material solution is a solvent that stabilizes the compound contained in the raw material solution (for example, an organic solvent such as an alcohol such as ethanol, dimethylformamide, or water), and hydrolyzes the compound contained in the raw material solution. And a catalyst (for example, hydrochloric acid, nitric acid, etc.) that smoothly proceeds the hydrolysis reaction. Also included in the raw material solution, for example, a chelating agent that stabilizes the compound, a silane coupling agent for stabilizing the compound, a compound that can impart various functions such as piezoelectricity, an adhesion improvement, An organic compound (for example, polymethyl methacrylate) for adjusting flexibility and hardness (fragility), or an additive such as a dye may be included. These additives can be added before hydrolysis, during hydrolysis, or after hydrolysis.
In the case of tetraethoxysilane, it is difficult to obtain a spinnable sol solution when the amount of water exceeds 4 times (molar ratio) of the alkoxide, and therefore it is preferably 4 times or less of the alkoxide.
When a base is used as the catalyst, it is difficult to obtain a spinnable sol solution, and therefore it is preferable not to use a base.
The reaction temperature may be equal to or lower than the boiling point of the solvent used, but the lower the reaction rate, the slower the reaction rate, and the easier to form a spinnable sol solution. Since it is difficult for the reaction to proceed even if it is too low, it is preferably 10 ° C. or higher.
[0012]
Next, in the manufacturing method of the present invention, the integration step (2) is performed. That is, the sol solution obtained in the step (1) is extruded from a nozzle and thinned by applying an electric field to the extruded sol solution to form inorganic gel-like fine fibers and supported. Accumulate inorganic gel-like fine fibers on the body.
[0013]
The diameter of the nozzle for extruding the sol solution varies depending on the fiber diameter of the target inorganic dry gel fine fiber or inorganic sintered fine fiber. For example, when the fiber diameter of the inorganic dry gel-like fine fibers or inorganic sintered fine fibers is 2 μm or less, the nozzle diameter is preferably about 0.1 to 3 mm.
The nozzle may be made of metal or non-metal. If the nozzle is made of metal, the nozzle can be used as one electrode. If the nozzle is made of non-metal, an electric field is applied to the extruded sol solution by installing an electrode in the nozzle. Can do.
[0014]
After extruding the sol solution from such a nozzle, the extrudate is stretched and reduced in diameter by applying an electric field to form inorganic gel-like fine fibers. This electric field varies depending on the fiber diameter of the target inorganic dry gel fine fiber or inorganic sintered fine fiber, the distance between the nozzle and the support, the solvent of the raw material solution, the viscosity of the sol solution, etc. For example, when the fiber diameter of the inorganic dry gel-like fine fibers or the inorganic sintered fine fibers is about 3 μm or less, it is preferably 0.5 to 5 kV / cm. If the electric field to be applied is large, the fiber diameter of the inorganic gel-like fine fibers becomes thin as the electric field value increases. However, if the electric field exceeds 5 kV / cm, it is not preferable because air breakdown tends to occur. Moreover, when it is less than 0.5 kV / cm, it is difficult to form a fiber shape.
By applying an electric field, an electrostatic charge is accumulated in the sol solution, and is electrically pulled and stretched by the electrode on the support side to form a fine fiber. In particular, since the fibers are electrically stretched, the speed of the fibers is accelerated by the electric field as the fibers approach the support, and the fibers become finer. In addition, it is thought that it becomes thinner due to evaporation of the solvent, the electrostatic density in the sol increases, and it splits due to its electric repulsive force. The present invention is not limited to the above reasoning.
[0015]
Such an electric field can be applied, for example, by providing a potential difference between the nozzle (the nozzle itself in the case of a metallic nozzle, the electrode in the nozzle in the case of a nonmetallic nozzle) and the support. it can. For example, a potential difference can be provided by applying a voltage to the nozzle and grounding the support, and conversely, a potential difference can be provided by applying a voltage to the support and grounding the nozzle.
[0016]
In this way, the inorganic gel-like fine fibers formed by applying an electric field and reducing the diameter are accumulated on the support. The support is a simple mounting type carrier used for the purpose of simply placing and collecting the inorganic gel-like fine fibers thereon, or by combining and integrating with the inorganic gel-like fine fibers. It can be a component carrier that is a component of an inorganic structure. Examples of the support as a simple mounting type carrier include a porous roll and a non-porous roll. Examples of the support that can be used as a simple mounting carrier or component carrier include a porous sheet (for example, a woven fabric, a knitted fabric, a nonwoven fabric, or a porous film sheet), or a non-porous sheet (for example, a film). be able to. The support as the component carrier can be composed of fibers (for example, organic fibers or inorganic fibers) or yarns. In addition, although such a support body may be planar, it can also have a three-dimensional solid shape. Here, the support having a three-dimensional solid shape means that it is not a planar sheet, and is, for example, a three-dimensional molded body obtained by bending and / or bending a sheet-like material. Can be adapted to various applications. For example, if it is a support body processed into a bellows shape, it can be suitably used for filter applications, and if it is a cylindrical support body, it can be suitably used for filter applications for liquids, and has a bowl shape. If it is this support body, it can be conveniently used as a mask.
[0017]
The support has a volume resistance of 10 when it is used as one of the electrodes.⁹It is preferably made of a conductive material (for example, made of metal) of Ω or less. On the other hand, when the conductive material is disposed as the counter electrode behind the support as viewed from the nozzle side, the support does not necessarily need to be a conductive material. As in the latter case, when the counter electrode is disposed behind the support, the support and the counter electrode may be in direct contact with each other or may be separated from each other.
[0018]
In addition, before the inorganic gel-like fine fibers pushed out from the nozzle and reduced in diameter by applying an electric field arrive at the support, the organic gel fibers and the inorganic fibers are used against the inorganic gel-like fine fibers. Threads made of these fibers, powders, etc. can be sprayed with an air gun or the like. According to this method, the sprayed fibers and / or powders are supported in a mixed state with inorganic gel-like fine fibers. It can be accumulated on the body. Such spraying of fibers, powders, and the like can be performed from any direction with respect to the direction in which the inorganic gel-like fine fibers are directed to the support. For example, the inorganic gel-like fine fibers are directed to the support. It can be sprayed from a direction perpendicular to the direction or from an oblique direction.
Examples of the powder include inorganic powders such as titanium oxide, manganese dioxide, copper oxide, silicon dioxide, activated carbon and platinum, and organic powders such as ion exchange resins, dyes, pigments and drugs. Can be mentioned. The average particle size of the powder is not particularly limited, but is preferably 0.01 to 100 μm, more preferably 0.05 to 10 μm. By including such a powder, a catalyst function, a polishing function, an adsorption function, an ion exchange function, or the like can be provided.
[0019]
The direction in which the sol solution is pushed out from the nozzle generally coincides with the direction in which the fine inorganic gel-like fine fibers are accumulated on the support. Further, these directions are not particularly limited. For example, the inorganic gel-like fine fibers can be moved from the nozzle arranged above to the support arranged below, and conversely, The inorganic gel-like fine fibers can be moved in a substantially vertical direction from the nozzle arranged in the above toward the support disposed in the upper direction, or can be pushed out in a substantially horizontal direction. However, it is preferable that the direction of extrusion from the nozzle does not coincide with the direction of action of gravity so that the gel does not easily drop. In particular, it is preferable to extrude in the direction opposite to the direction of gravity or in the direction perpendicular to the direction of gravity.
[0020]
Thus, strength, moldability, etc. are obtained by mixing inorganic gel-like fine fibers and sprayed fibers and / or powders, etc., or by combining inorganic gel-like fine fibers and a support (component carrier). It is possible to produce an inorganic structure excellent in various properties.
[0021]
In the production method of the present invention, the drying step (3) can be performed following the accumulation step (2). That is, the inorganic gel-like fine fibers accumulated in the accumulation step (2) are dried to form an inorganic structure including the inorganic dry gel-like fine fibers.
Or in the manufacturing method of this invention, following the said integration | stacking process (2), a drying process (3) can be implemented similarly to the above, and a sintering process (4) can be implemented further. That is, after drying the inorganic gel-like fine fibers accumulated in the collecting step (2) to form an inorganic structure containing the inorganic dry gel-like fine fibers, the inorganic dry gel-like fine fibers are contained. The inorganic structure can be sintered to form an inorganic structure including inorganic sintered fine fibers.
Furthermore, in the manufacturing method of the present invention, the sintering step (4) can be carried out following the collecting step (2) without carrying out the drying step (3). That is, the inorganic gel-like fine fibers accumulated in the accumulation step (2) can be sintered to form an inorganic structure including the inorganic sintered fine fibers.
Therefore, there are two types of inorganic structures obtained by the production method of the present invention, including cases where inorganic dry gel-like fine fibers are included and cases where inorganic sintered fine fibers are included.
[0022]
First, the drying step (3) will be described.
When the inorganic gel-like fine fibers accumulated in the collecting step (2) are dried to form an inorganic structure containing the inorganic dry gel-like fine fibers, the drying temperature constitutes the inorganic gel-like fine fibers. However, it is preferably carried out at a temperature lower than the decomposition temperature of the organic component, for example, a temperature of about 200 ° C. or lower. This drying can be performed by heating in an oven or the like, and can also be performed by freeze drying or supercritical drying.
[0023]
In the drying process, the film is dried until it has a handling strength necessary for application to various uses. Further, the inorganic dry gel-like fine fibers are intertwined with each other or bonded by adhesion due to volatilization of the solvent.
[0024]
In this drying step (3), the inorganic gel-like fine fibers are dried in an integrated state with the support (component carrier), and the inorganic dry gel-like fine fibers and the support (component carrier) are integrated. Inorganic structure is obtained, or after drying, the inorganic dry gel-like fine fibers are separated from the support (simple mounting carrier) to form an inorganic structure composed of inorganic dry gel-like fine fibers. . In either case, the constituent fibers are bonded to each other without using an adhesive, and almost no dropout occurs.
[0025]
According to the manufacturing method of the present invention, the sintering step (4) can be performed after the accumulation step (2) without performing the drying step (3). In this case, since the sintering temperature varies depending on the inorganic component constituting the inorganic gel-like fine fiber, it is not particularly limited. For example, an inorganic gel-like fine fiber containing an inorganic component and an organic component, Sintering at a temperature of about 200 ° C. or more and less than the decomposition temperature of the organic component can produce an inorganic structure in which the organic component remains, and the inorganic structure can function as a function of the remaining organic component (for example, adhesion) Property improvement, flexibility, hardness (brittleness) adjustment, optical functions such as pigment, water repellency). In the inorganic structure obtained by sintering in this manner, the constituent fibers are bonded to each other even by sintering, so that almost no dropout occurs. Moreover, if it sinters more than the decomposition temperature of an organic component, the inorganic type structure which consists only of an inorganic component, and contains the inorganic sintered fine fiber which is excellent in intensity | strength and heat resistance can be manufactured.
[0026]
More specifically, when the inorganic gel-like fine fiber is composed of a silica component containing an organic component, it is sintered at a temperature of about 200 to 400 ° C. Inorganic structures having improved properties, flexibility, hardness (brittleness) adjustment, optical functions such as pigments, and water repellency can be produced. If sintered at a temperature of 800 ° C. or higher, organic components An inorganic structure including a silica sintered fine fiber not included can be manufactured.
In addition, if the accumulated inorganic gel-like fine fibers are suddenly sintered at the sintering temperature, the inorganic gel-like fine fibers may be rapidly contracted and damaged. Sintering is preferred.
[0027]
In the production method of the present invention, after the accumulation step (2), the drying step (3) can be performed, and then the sintering step (4) can be performed. In this case, the formation of the inorganic structure including the inorganic dry gel-like fine fibers in the preceding drying step (3) can be performed in the same manner as the operation in the drying step (3) performed alone. Moreover, formation of the inorganic type structure containing an inorganic type sintered fine fiber by a latter stage sintering process (4) can be implemented similarly to operation in the above-mentioned sintering process (4) implemented independently. In addition, since sintering process (4) implemented after a drying process (3) is implemented with respect to the inorganic type structure containing the inorganic type dry gel-like fine fiber already dried, it is made to raise temperature gradually to sintering temperature. There is no need to sinter. By carrying out the drying step (3) and the sintering step (4) in succession, it consists of inorganic sintered fine fiber-containing inorganic structure with organic components remaining, or inorganic components alone, and has strength and heat resistance. An inorganic structure containing inorganic sintered fine fibers having excellent properties can be produced.
[0028]
The inorganic dry gel-like fine fibers or inorganic sintered fine fibers thus produced by the production method of the present invention can contain inorganic or organic fine particles therein. Such fine particles can be present, for example, when the sol solution is formed by the hydrolysis reaction as described above, or by mixing before pushing out the sol solution from the nozzle.
[0029]
Examples of the inorganic fine particles can include metals such as titanium oxide, manganese dioxide, copper oxide, silicon dioxide, activated carbon, or platinum, and examples of the organic fine particles include dyes or pigments. Can do. 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 including such a powder, an optical function, porosity, catalytic function, adsorption function, ion exchange function, or the like can be provided.
[0030]
The manufacturing method of the present invention will be described with reference to FIG. 1 which is a schematic sectional view of a manufacturing apparatus. First, the sol solution prepared as described above is supplied from the sol solution storage unit 1 to the metal nozzles 21 to 24 by a metering pump or the like. The supply amount to the nozzles 21 to 24 is not particularly limited, and can be changed, for example, from 0.01 mL / hour to 100 mL / hour per nozzle. In FIG. 1, four nozzles 21 to 24 are provided, but the number of nozzles is not particularly limited as long as it is one or more.
[0031]
Thus, the sol solution supplied to the nozzles 21 to 24 is pushed out from the nozzles 21 to 24. Meanwhile, a voltage is applied to the four nozzles 21 to 24. Specifically, as viewed from the nozzles 21 to 24, since the counter electrode 3 located behind the support 4 is grounded, the metal nozzles 21 to 24 connected to the power supply 30 and the support 4 An electric field is formed between them, and the extruded sol solution is stretched and thinned by the electric field to form inorganic gel-like fine fibers. The position of the nozzles 21 to 24 is changed so that the electric field strength can be adjusted to 0.5 to 5 kV / cm, and the distance between the nozzles 21 to 24 and the support 4 is preferably about 10 to 500 mm. More preferably, it can be changed to about 50 to 300 mm. In contrast to the above method, the nozzles 21 to 24 may be grounded and a voltage may be applied to the counter electrode 3.
[0032]
Although not shown, since the sol solution is easily cured and difficult to spin stably when the tip portions of the nozzles 21 to 24 are dried, the atmosphere at the tip portions of the nozzles 21 to 24 is the same solvent as the raw material solution. It is preferable to prevent drying at the tip portions of the nozzles 21 to 24 by using a gas atmosphere or adding a high boiling point solvent (for example, butanol) having a boiling point of 100 ° C. or higher to the sol solution.
[0033]
The inorganic gel-like fine fibers formed by stretching the sol solution extruded from the nozzles 21 to 24 are accumulated on the support 4. The support 4 is, for example, a net-like endless belt, and moves in the direction of arrow d as the rollers 41, 42, and 43 rotate in the directions of arrows a, b, and c, respectively. This amount of accumulation can be adjusted by the moving speed of the net belt, the amount of extrusion from the nozzle, the number of nozzles, and the like.
The inorganic gel-like fine fibers accumulated on the support 4 are supplied to the heating unit, for example, the heater 5 by the movement of the support (simple mounting type carrier) 4 and dried by the heat of the heater 5, and the inorganic drying is performed. It becomes an inorganic structure (inorganic dry gel-like fine fiber-containing sheet) containing gel-like fine fibers. In addition, it is preferable that the area | region containing the heater 5 is separated and separated from the other part as the drying chamber 8. FIG.
Next, after the thickness of the inorganic structure (inorganic dry gel-like fine fiber-containing sheet) containing the inorganic dry gel-like fine fibers is adjusted by the presser roll 6, the support (simple mounting type carrier) 4 is used. It separates and is wound up by the winding roll 10 from the guide roll 10a.
According to the manufacturing method described above, an inorganic structure composed only of inorganic dry gel-like fine fibers can be obtained.
[0034]
On the other hand, instead of the net-like endless belt support (simple placement type carrier) 4 used in the above-described manufacturing method, a woven fabric, a knitted fabric, a non-woven fabric, or a net is guided as a support (component carrier) 4 from an unwinding roll 9 A composite inorganic structure having an inorganic dry gel-like fine fiber layer on a woven fabric, a knitted fabric, a non-woven fabric, or a net by being put on the track of rollers 43, 42, 41 through a roll 9a and supplying the sol solution to an extrusion region. Can be manufactured. After the thickness of the composite inorganic structure obtained in this way is adjusted by the presser roll 6, the two are integrally wound by the take-up roll 10 from the guide roll 10 a.
[0035]
Although not shown, a support having a three-dimensional shape (for example, a support folded in a bellows shape, a cylindrical support, a bowl-shaped support, etc.), a sol solution is used. If it supplies to the area | region to extrude, a three-dimensional composite inorganic type structure can be manufactured.
[0036]
Since the solvent in the raw material solution is volatilized, the region where the sol solution is extruded is preferably separated from other parts and separated as a spinning chamber 7, which is made of a material that is not affected by the solvent. It is preferable. The spinning chamber 7 is preferably provided with an exhaust port 71 through which the volatilized solvent can be exhausted.
Furthermore, although not shown in the figure, an electric furnace or the like for sintering treatment can be installed after the heater 5 so that the drying process and the sintering process can be carried out continuously. Or it replaces with the heater 5 and can install an electric furnace etc. and can implement a sintering process, without implementing a drying process.
[0037]
According to such a method for producing an inorganic structure of the present invention, the inorganic gel-like fine fibers are dried or sintered, or the inorganic dry gel-like fine fibers are sintered to substantially reduce the adhesive. Since it can join without using, the inorganic type structure which does not have the trouble by using an adhesive agent can be manufactured.
[0038]
Further, according to the method for producing an inorganic structure of the present invention, the electric field strength, the discharge amount of the sol solution from the nozzle, the amount of the solvent in the sol solution, or the atmosphere in the discharge portion (the same solvent gas atmosphere as the sol solution) It is possible to manufacture an inorganic structure including an inorganic dry gel-like ultrafine fiber or an inorganic sintered ultrafine fiber having a fiber diameter of 2 μm or less. Excellent properties such as filtration performance, flexibility and separation performance. When the inorganic structure of the present invention contains an inorganic dry gel-like ultrafine fiber or an inorganic sintered ultrafine fiber having a fiber diameter of 2 μm or less, because it is excellent in flexibility, by bending and / or curving, Various shapes can be used. For example, it can be wound into a hollow cylindrical shape, an internal solid cylindrical shape, or folded into a bellows shape.
[0039]
Furthermore, according to the method for producing an inorganic structure of the present invention, inorganic dry gel-like fine fibers or inorganic sintered fine fibers having a fiber length longer than the fiber diameter, that is, an aspect ratio (fiber length / fiber diameter). ) Large inorganic dry gel-like elongated fibers or inorganic sintered elongated fibers can be produced, and these inorganic structures are inorganic dry gel-like elongated fibers or inorganic sintered elongated fibers. Is hard to fall off.
[0040]
Furthermore, according to the method for producing an inorganic structure of the present invention, an inorganic dry gel fine fiber or an inorganic sintered fine fiber having a fiber diameter CV value (standard deviation / average fiber diameter) of 0.8 or less. The inorganic type structure which consists of can be manufactured. In this specification, “fiber diameter” means the diameter when the fiber cross-sectional shape is circular, and when the fiber cross-sectional shape is non-circular, the diameter of a circle having the same area as the cross-sectional area is defined. Considered as fiber diameter. “Average fiber diameter” means an average value of fiber diameters at 100 fibers, and “standard deviation” is a value obtained from fiber diameters at 100 fibers. Inorganic dry gel-like fine fibers or inorganic sintered fine fibers having a CV value of 0.8 or less are preferred in that the performance of the inorganic structure becomes uniform. The CV value is preferably 0.7 or less, more preferably 0.6 or less, still more preferably 0.5 or less, and most preferably 0.4 or less.
[0041]
  Therefore, the inorganic structure manufactured by the manufacturing method of the present invention includes, for example, a filter material for HEPA filter, a filter material for ULPA filter, a filter material for clean room filter, a filter material for pure water filter, and a heat resistant filter.ForFilter material, filter material for exhaust gas filter, filter material for liquid filter, substrate for photocatalyst support, battery separator, substrate for printed circuit board, catalyst sheet, electromechanical transducer, fine bubble generation sheet, catalyst combustion sheet, solar It can be suitably used for applications such as a battery cover material, a heat insulating material, or a liquid crystal spacer material.
[0042]
The present invention also relates to an inorganic structure having an average fiber diameter of 2 μm or less and including inorganic extra long fibers mainly composed of inorganic components. The inorganic ultrafine fiber-containing inorganic structure according to the present invention can be produced, for example, by the production method according to the present invention.
[0043]
When the average fiber diameter of the inorganic extra-fine long fibers is 2 μm or less, the flexibility is excellent, and the wide surface area provides various functions (for example, filtration performance, function performance performance by functional substances, etc.). ing. A more preferable average fiber diameter is 1 μm or less, and a further preferable average fiber diameter is 0.5 μm or less. On the other hand, the lower limit of the average fiber diameter of the inorganic ultrafine fibers is not particularly limited, but about 0.01 μm is appropriate.
[0044]
In addition, since the average fiber diameter of the inorganic ultrafine fibers is 2 μm or less, the inorganic ultrafine fibers may include a portion exceeding 2 μm. However, the inorganic ultrafine fibers have a fiber diameter at any point. Is preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less.
[0045]
The inorganic ultrafine fiber-containing inorganic structural body of the present invention is an inorganic structural body in which fibers are difficult to drop off because the inorganic ultrafine fibers constituting the inorganic structural body are long fibers.
[0046]
The inorganic extra long fibers contained in the inorganic structure of the present invention are mainly composed of inorganic components. That is, the inorganic component accounts for 50% by mass or more, preferably 60% by mass or more, more preferably 75% by mass or more.
[0047]
The elements constituting the inorganic component are not particularly limited, but can include the elements listed in the sol solution forming step (1) of the production method according to the present invention, and compounds containing the elements (that is, Examples of the compound (especially oxide) include the oxides listed in the sol solution forming step (1).
[0048]
The inorganic extra long fibers contained in the inorganic structure of the present invention can contain an organic component in addition to the inorganic component as described above. Examples of the organic component include the organic components described in the production method according to the present invention (for example, organic low molecular compounds such as silane coupling agents and dyes, and organic high molecular compounds such as polymethyl methacrylate).
[0049]
In addition, as described in the manufacturing method according to the present invention, the inorganic extra-fine long fibers may contain inorganic or organic fine particles in the fibers. Such fine particles can be present, for example, by the method described in the production method according to the present invention.
[0050]
Since the inorganic ultrafine fiber-containing inorganic structure of the present invention includes the inorganic ultrafine fiber as described above, the fiber is difficult to fall off and is excellent in flexibility. The content of the inorganic extra long fibers contained in the inorganic structure of the present invention is not particularly limited, but is preferably 1% by mass or more based on the total mass of the inorganic structure (excluding the support). More preferably, it is 5 mass% or more. It should be noted that the inorganic structure according to the present invention may contain powder or fine particles.
[0051]
In addition, when the inorganic extra long fibers constituting the inorganic structure of the present invention are bonded at the contact point without using an adhesive, the adhesive is substantially contained in the inorganic structure of the present invention. Since no exists, the generation of pollutants can be suppressed.
[0052]
In addition, the inorganic extra long fibers constituting the inorganic structure of the present invention may be, for example, in a state where the gel is dried, in a state where the gel is incompletely sintered, or the gel is completely It may be in a sintered state.
[0053]
Furthermore, the inorganic structure of the present invention includes organic fibers, inorganic fibers having a large fiber diameter exceeding 2 μm, inorganic short fibers, and yarns composed of these fibers, in addition to the inorganic extra long fibers. , A woven fabric, a knitted fabric, a non-woven fabric, a net, or a powder or the like. By being in a mixed or compounded state in this way, various properties such as strength and moldability of the inorganic structure can be improved and applied to a wide range of applications.
[0054]
Since the inorganic structure of the present invention is excellent in flexibility as described above, it can take various shapes. For example, a sheet shape, a plate shape, a block shape, a hollow cylindrical shape, an internal solid cylindrical shape, or the like can be adopted.
[0055]
The inorganic ultrafine fiber-containing inorganic structure of the present invention can be produced, for example, by the production method according to the present invention. However, in order to set the average fiber diameter to 2 μm or less, spinning can be performed by appropriately setting the discharge amount, the viscosity (sol solution), the solvent of the sol solution, the electric field strength, and the type of the compound. These conditions can be set by repeating the experiment.
[0056]
In the drying step (3) of the production method according to the present invention, the inorganic gel-like elongated fibers are dried in an integrated state with the support (component carrier), and the inorganic gel-like elongated fibers and the support (component carrier) are dried. To obtain an inorganic structure in a state in which the inorganic gel is obtained, or after drying, the inorganic gel-like ultrafine fibers are separated from the support (simple mounting type carrier) to form an inorganic gel-like ultrafine fiber. A system structure can be formed. In either case, the constituent fibers are bonded to each other without using an adhesive, and almost no dropout occurs.
[0057]
In the manufacturing method according to the present invention, after the accumulation step (2), the sintering step (4) is performed without performing the drying step (3), and includes, for example, an inorganic component and an organic component. If the inorganic gel-like ultrafine fibers are sintered at a temperature of about 200 ° C. or higher and less than the decomposition temperature of the organic component, an inorganic sintered ultrafine fiber-containing inorganic structure in which the organic component remains can be produced. This inorganic structure can exhibit the function of the remaining organic component. In the inorganic structure obtained by sintering in this manner, the constituent fibers are bonded to each other even by sintering, so that almost no dropout occurs. Moreover, if it sinters more than the decomposition temperature of an organic component, the inorganic type structure which consists only of an inorganic component, and contains the inorganic sintering extra-fine fiber excellent in intensity | strength and heat resistance can be manufactured.
[0058]
In the manufacturing method according to the present invention, after the accumulation step (2), the drying step (3) is performed, and then the sintering step (4) is further performed, whereby an inorganic component remains. It is possible to produce a sintered ultrafine fiber-containing inorganic structure, or an inorganic structure made of only inorganic components and containing an inorganic sintered ultrafine fiber having excellent strength and heat resistance.
[0059]
When the CV value of the fiber diameter of the inorganic ultrafine fiber according to the present invention is 0.8 or less, it is preferable in that the performance of the inorganic structure becomes uniform. The CV value is preferably 0.7 or less, more preferably 0.6 or less, still more preferably 0.5 or less, and most preferably 0.4 or less.
[0060]
  Since the inorganic ultrafine fiber-containing inorganic structure of the present invention is such that the fibers are less likely to fall off, have excellent flexibility, have a large surface area, excellent heat resistance, and are less likely to generate contaminants. For example, HEPA filter media, ULPA filter media, clean room filter media, pure water filter media, heat resistant filterForFilter material, filter material for exhaust gas filter, filter material for liquid filter, substrate for photocatalyst support, battery separator, substrate for printed circuit board, catalyst sheet, electromechanical transducer, fine bubble generation sheet, catalyst combustion sheet, solar It can be suitably used for applications such as a battery cover material, a heat insulating material, or a liquid crystal spacer material.
[0061]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.
[Example 1]
(1) Sol solution formation process
Tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and 1N hydrochloric acid as a catalyst are mixed at a molar ratio of 1: 5: 2: 0.03 at a temperature of 78 ° C. for 10 hours. Then, after removing the solvent by a rotary evaporator, the mixture was heated to 50 ° C. to form a sol solution having a viscosity of about 20 poise.
[0062]
(2) Accumulation process
Next, the sol solution is supplied to a stainless steel nozzle having an inner diameter of 0.5 mm at a rate of 1.2 mL / hour per nozzle by a pump, the sol solution is pushed out from the nozzle, and a voltage (25 kV) is applied to the nozzle. In addition, a non-porous stainless steel roll as a support (simple mounting type carrier) is grounded, and the diameter is reduced by applying an electric field (2.5 kV / cm) to the extruded sol solution, thereby forming an inorganic gel-like elongated fiber. Was accumulated on a rotating stainless steel non-porous roll. The distance between the nozzle and the stainless steel non-porous roll was 10 cm.
[0063]
(3) Drying process
Next, the accumulated inorganic gel-like elongated fibers are dried by a heater set at a temperature of 150 ° C., and the inorganic fiber-like elongated fibers having an average fiber diameter of 3 μm (the fiber diameter at any point is about 3 μm) ( SiO₂An inorganic structure consisting of Inorganic dry gel-like elongated fibers (SiO2) constituting this inorganic structure₂Was composed of no contact with an adhesive agent and no pollutant was generated. Further, this inorganic dry gel structure did not crack even when bent, and the fibers did not fall off.
[0064]
(4) Sintering process
Next, the inorganic structure comprising the inorganic dry gel-like elongated fibers was sintered at a temperature of 150 ° C. for 5 hours, at a temperature of 300 ° C. for 5 hours, and at a temperature of 1000 ° C., and completely vitrified to obtain an average fiber diameter. Produced an inorganic structure composed of quartz glass sintered ultrafine fibers having a diameter of 2 μm (fiber diameter at any point is about 2 μm). The quartz glass sintered ultrafine fibers of this inorganic structure were bonded without any adhesive at the contact points, and did not generate contaminants. Further, this inorganic sintered structure was not cracked even when it was bent, and the fibers did not fall off.
[0065]
[Example 2]
An inorganic dry gel having an average fiber diameter of 1 μm (fiber diameter at any point is also about 1 μm) in exactly the same manner as in Examples 1 (1) to (3) except that a sol solution of about 10 poise was used. -Like ultra-thin fibers (SiO₂An inorganic structure consisting of Inorganic dry gel-like ultrafine fibers (SiO2) constituting this inorganic structure₂Was composed of no contact with an adhesive agent and no pollutant was generated. Further, this inorganic dry gel structure did not crack even when bent, and the fibers did not fall off.
Subsequently, the inorganic structure made of the inorganic dry gel ultrafine fibers was sintered in the same manner as in Example 1 (4) and completely vitrified, so that the average fiber diameter was 0.8 μm (fiber at any point). An inorganic structure made of quartz glass sintered ultrafine fibers having a diameter of about 0.8 μm was manufactured. The quartz glass sintered ultrafine fibers of this inorganic structure were bonded without any adhesive at the contact points, and did not generate contaminants. Further, this inorganic sintered structure was not cracked even when it was bent, and the fibers did not fall off.
[0066]
[Example 3]
The sol solution having a viscosity of about 3.5 poise by adding butanol was used, the supply amount of the sol solution per nozzle was 0.8 mL / hour, and the applied voltage to the nozzle was 20 kV Except for the above, it was exactly the same as in Examples 1 (1) to (3), and an inorganic dry gel-like ultra-thin fiber having an average fiber diameter of 0.6 μm (the fiber diameter at any point was also about 0.6 μm). Fiber (SiO₂An inorganic structure consisting of This inorganic dry gel-like ultra-thin fiber was bonded at the contact point without using an adhesive, and did not generate contaminants. Further, this inorganic dry gel structure did not crack even when bent, and the fibers did not fall off.
Next, the inorganic structure composed of the inorganic dry gel-like ultrafine fibers was sintered in the same manner as in Example 1 (4) and completely vitrified to obtain an average fiber diameter of 0.4 μm (any point) An inorganic structure made of quartz glass sintered ultrafine fibers having a fiber diameter of about 0.4 μm was manufactured. In addition, the quartz glass sintered ultrafine fiber was bonded without any adhesive at the contact point, and did not generate a contaminant. Further, this inorganic sintered structure was not cracked even when it was bent, and the fibers did not fall off.
[0067]
[Example 4]
The sol solution having a viscosity of about 1.5 poise by adding butanol was used, the supply amount of the sol solution per nozzle was 0.6 mL / hour, and the applied voltage to the nozzle was 20 kV Except for the above, inorganic dry gel ultrafine fibers having an average fiber diameter of 0.2 μm (fiber diameter at any point is about 0.2 μm) are the same as in Examples 1 (1) to (3). (SiO₂An inorganic dry gel structure (inorganic dry gel nonwoven fabric) made of Inorganic dry gel ultrafine fibers (SiO2) constituting this inorganic dry gel structure (inorganic dry gel nonwoven fabric)₂Was composed of no contact with an adhesive agent and no pollutant was generated. Further, this inorganic dry gel structure did not crack even when bent, and the fibers did not fall off.
[0068]
Furthermore, this inorganic dry gel structure (inorganic dry gel nonwoven fabric) was sintered at a temperature of 150 ° C. for 5 hours, at a temperature of 300 ° C. for 5 hours, and at a temperature of 800 ° C., and completely vitrified to obtain an average fiber diameter. Produced an inorganic sintered structure (inorganic sintered nonwoven fabric) made of inorganic sintered ultrafine fibers (quartz glass ultrafine fibers) having a fiber diameter of 0.15 μm (fiber diameter at any point is about 0.15 μm). . In addition, the inorganic sintered ultrafine fibers (quartz glass ultrafine fibers) were bonded at the contacts without any adhesive, and did not generate contaminants. Further, this inorganic sintered structure was not cracked even when it was bent, and the fibers did not fall off.
[0069]
[Example 5]
(1) Sol solution formation process
Tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and 1N hydrochloric acid as a catalyst were mixed at a molar ratio of 1: 5: 2: 0.003 at a temperature of 78 ° C. for 15 hours. The solvent was removed by a rotary evaporator and then heated to a temperature of 60 ° C. to form a sol solution having a viscosity of about 2 poise.
[0070]
(2) Accumulation process
Next, a sol solution is supplied to a stainless steel nozzle having an inner diameter of 0.7 mm at a rate of 1 mL / hour per nozzle by a pump, the sol solution is pushed out from the nozzle, and a voltage (16.5 kV) is applied to the nozzle. A non-porous stainless steel roll as a support (simple mounting type carrier) is grounded, and an electric field (1.65 kV / cm) is applied to the extruded sol solution to make it an ultrafine fiber. It was formed and accumulated on a rotating stainless steel non-porous roll. The distance between the nozzle and the stainless steel non-porous roll was 10 cm.
[0071]
(3) Drying process
Next, the collected inorganic gel-like ultralong fibers are dried for 1 hour by a heater set at a temperature of 150 ° C.₂An inorganic structure consisting of Inorganic dry gel-like ultrafine fibers (SiO2) constituting this inorganic structure₂Was composed of no contact with an adhesive agent and no pollutant was generated. In addition, this inorganic structure was not cracked even when it was bent, and the fibers did not fall off.
[0072]
(4) Sintering process
Next, the inorganic structure made of the inorganic dry gel-like ultrafine fibers was sintered at a temperature of 800 ° C. for 1 hour and completely vitrified to have an average fiber diameter of 0.6 μm (the fiber diameter at any point was An inorganic structure made of quartz glass sintered ultrafine fibers of about 0.6 μm) was produced. The CV value was 0.4. The quartz glass sintered ultrafine fibers of this inorganic structure were bonded without any adhesive at the contact points, and did not generate contaminants. Further, this inorganic sintered structure was not cracked even when it was bent, and the fibers did not fall off.
[0073]
[Example 6]
(1) Sol solution formation process
Tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and 1N hydrochloric acid as a catalyst are mixed at a molar ratio of 1: 5: 2.5: 0.003 at a temperature of 78 ° C., 15 Then, the solvent was removed by a rotary evaporator and heated to a temperature of 60 ° C. to form a sol solution having a viscosity of about 2.5 poise.
[0074]
(2) Accumulation process
Next, a sol solution is supplied to a stainless steel nozzle having an inner diameter of 0.7 mm at a rate of 1 mL / hour per nozzle by a pump, the sol solution is pushed out from the nozzle, and a voltage (17.5 kV) is applied to the nozzle. A stainless steel non-porous roll as a support (simple mounting type carrier) is grounded, and an electric field (1.75 kV / cm) is applied to the extruded sol solution to make it ultrafine, and an inorganic gel-like ultrafine fiber is obtained. It was formed and accumulated on a rotating stainless steel non-porous roll. The distance between the nozzle and the stainless steel non-porous roll was 10 cm.
[0075]
(3) Drying process
Next, the collected inorganic gel-like ultralong fibers are dried for 1 hour by a heater set at a temperature of 150 ° C.₂An inorganic structure consisting of Inorganic dry gel-like ultrafine fibers (SiO2) constituting this inorganic structure₂Was composed of no contact with an adhesive agent and no pollutant was generated. Further, this inorganic dry gel structure did not crack even when bent, and the fibers did not fall off.
[0076]
(4) Sintering process
Next, the inorganic structure composed of the inorganic dry gel-like ultrafine fibers was sintered at a temperature of 800 ° C. for 1 hour and completely vitrified to have an average fiber diameter of 0.5 μm (the fiber diameter at any point was An inorganic structure made of quartz glass sintered ultrafine fibers of about 0.5 μm) was produced. The CV value was 0.4. The quartz glass sintered ultrafine fibers of this inorganic structure were bonded without any adhesive at the contact points, and did not generate contaminants. Further, this inorganic sintered structure was not cracked even when it was bent, and the fibers did not fall off.
[0077]
[Example 7]
(1) Sol solution formation process
Tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and 1N hydrochloric acid as a catalyst were mixed at a molar ratio of 1: 5: 3: 0.003 at a temperature of 78 ° C. for 15 hours. The solvent was removed by a rotary evaporator and then heated to a temperature of 60 ° C. to form a sol solution having a viscosity of about 3 poise.
[0078]
(2) Accumulation process
Next, a sol solution is supplied to a stainless steel nozzle having an inner diameter of 0.7 mm at a rate of 1 mL / hour per nozzle by a pump, the sol solution is pushed out from the nozzle, and a voltage (20 kV) is applied to the nozzle. Grounding a stainless steel non-porous roll that is a (simple mounting type carrier), and making it extremely fine by applying an electric field (2 kV / cm) to the extruded sol solution, forming an inorganic gel-like ultrafine fiber, It was accumulated on a rotating stainless steel non-porous roll. The distance between the nozzle and the stainless steel non-porous roll was 10 cm.
[0079]
(3) Drying process
Next, the collected inorganic gel-like ultralong fibers are dried for 1 hour by a heater set at a temperature of 150 ° C.₂An inorganic structure consisting of Inorganic dry gel-like ultrafine fibers (SiO2) constituting this inorganic structure₂Was composed of no contact with an adhesive agent and no pollutant was generated. Further, this inorganic dry gel structure did not crack even when bent, and the fibers did not fall off.
[0080]
(4) Sintering process
Next, the inorganic structure made of the inorganic dry gel-like ultrafine fibers was sintered at a temperature of 800 ° C. for 1 hour and completely vitrified to have an average fiber diameter of 0.6 μm (the fiber diameter at any point was An inorganic structure made of quartz glass sintered ultrafine fibers of about 0.6 μm) was produced. The CV value was 0.3. The quartz glass sintered ultrafine fibers of this inorganic structure were bonded without any adhesive at the contact points, and did not generate contaminants. Further, this inorganic sintered structure was not cracked even when it was bent, and the fibers did not fall off.
[0081]
[Example 8]
(1) Sol solution formation process
  Tetraethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, and 1N hydrochloric acid as a catalyst were mixed at a molar ratio of 1: 5: 2: 0.003 at a temperature of 78 ° C. for 15 hours. Refluxing was performed to prepare a silica stock solution.
  Meanwhile, 2-propyl alcohol and aluminum sec−Butoxide and ethyl acetoacetate were mixed at a molar ratio of 0.4: 0.08: 0.08 and refluxed for 2 hours at a temperature of 78 ° C. to prepare an alumina-based stock solution.
  Next, the silica stock solution and the alumina stock solution were mixed at 78 ° C. for 2 hours, the solvent was removed by a rotary evaporator, and then heated to a temperature of 60 ° C. to form a sol solution having a viscosity of 2 poise.
[0082]
(2) Accumulation process
Next, a sol solution is supplied to a stainless steel nozzle having an inner diameter of 0.7 mm at a rate of 1 mL / hour per nozzle by a pump, the sol solution is pushed out from the nozzle, and a voltage (24 kV) is applied to the nozzle. A non-porous stainless steel roll, which is a (simple mounting type carrier), is grounded and an electric field (2.4 kV / cm) is applied to the extruded sol solution to make it ultrafine to form inorganic gel-like ultrafine fibers. And accumulated on a rotating stainless steel non-porous roll. The distance between the nozzle and the stainless steel non-porous roll was 10 cm.
[0083]
(3) Drying process
Next, the collected inorganic gel-like ultralong fibers were dried by a heater set at a temperature of 150 ° C. for 1 hour to produce an inorganic structure composed of silica-alumina inorganic dry gel-like ultralong fibers. The silica-alumina inorganic dry gel-like ultrafine fibers constituting the inorganic structure were bonded without using an adhesive at the contact point, and did not generate contaminants. In addition, this inorganic structure was not cracked even when it was bent, and the fibers did not fall off.
[0084]
(4) Sintering process
Next, the inorganic structure composed of the inorganic dry gel-like ultrafine fibers was sintered at a temperature of 1000 ° C. for 1 hour and completely vitrified to have an average fiber diameter of 0.5 μm (the fiber diameter at any point was An inorganic structure made of silica-alumina sintered ultrafine fibers (about 0.5 μm) was produced. The CV value was 0.22. The silica-alumina sintered ultrafine fibers of this inorganic structure were bonded without any adhesive present at the contact points, and did not generate contaminants. In addition, this inorganic structure was not cracked even when it was bent, and the fibers did not fall off.
[0085]
[Example 9]
(1) Sol solution formation process
Tetraethoxysilane as a metal compound, methyltriethoxysilane as a metal compound, ethanol as a solvent, water for hydrolysis, 1N hydrochloric acid as a catalyst, 0.75: 0.25: 5: 2: 0.003 The mixture was mixed at a molar ratio and refluxed at a temperature of 78 ° C. for 15 hours. Then, the solvent was removed by a rotary evaporator and then heated to a temperature of 60 ° C. to form a sol solution having a viscosity of about 2 poise. .
[0086]
(2) Accumulation process
Next, a sol solution is supplied to a stainless steel nozzle having an inner diameter of 0.7 mm at a rate of 1 mL / hour per nozzle by a pump, the sol solution is pushed out from the nozzle, and a voltage (17 kV) is applied to the nozzle. An organic inorganic (silica) hybrid-gel is obtained by grounding a stainless steel non-porous roll (simple mounting type carrier) and applying an electric field (1.7 kV / cm) to the extruded sol solution. The ultrafine fibers were formed and accumulated on a rotating stainless steel non-porous roll. The distance between the nozzle and the stainless steel non-porous roll was 10 cm.
[0087]
(3) Drying process
Next, the organic inorganic hybrid-gel-like ultrafine fibers thus accumulated are dried for 1 hour by a heater set at a temperature of 150 ° C., and an inorganic structure comprising the organic inorganic hybrid-dry gel-like ultrafine fibers. Manufactured. The organic inorganic hybrid-dried gel-like ultrafine fibers constituting the inorganic structure were bonded without using an adhesive at the contact point, and did not generate contaminants. In addition, this inorganic structure was not cracked even when it was bent, and the fibers did not fall off.
[0088]
(4) Sintering process
Subsequently, this inorganic inorganic hybrid-dried gel-like ultrafine fiber structure was sintered at a temperature of 500 ° C. for 1 hour, completely vitrified, and an average fiber diameter of 0.5 μm (any point) An inorganic structure composed of organic inorganic hybrid-sintered ultrafine fibers having a fiber diameter of about 0.5 μm was manufactured. The CV value was 0.4. The organic inorganic hybrid-sintered ultra-thin fibers of this inorganic structure were bonded at the contact point without any adhesive, and did not generate contaminants. In addition, this inorganic structure was not cracked even when it was bent, and the fibers did not fall off.
[0089]
[Example 10]
(1) Sol solution formation process
Tetraethoxysilane as metal compound, methyltriethoxysilane as metal compound, ethanol as solvent, water for hydrolysis, 1N hydrochloric acid as catalyst, 0.9: 0.1: 5: 2: 0.003 The mixture was mixed at a molar ratio and refluxed at a temperature of 78 ° C. for 15 hours. Then, the solvent was removed by a rotary evaporator and then heated to a temperature of 60 ° C. to form a sol solution having a viscosity of about 2 poise. .
[0090]
(2) Accumulation process
Next, a sol solution is supplied to a stainless steel nozzle having an inner diameter of 0.7 mm at a rate of 1 mL / hour per nozzle by a pump, the sol solution is pushed out from the nozzle, and a voltage (17 kV) is applied to the nozzle. An organic inorganic (silica) hybrid-gel is obtained by grounding a stainless steel non-porous roll (simple mounting type carrier) and applying an electric field (1.7 kV / cm) to the extruded sol solution. The ultrafine fibers were formed and accumulated on a rotating stainless steel non-porous roll. The distance between the nozzle and the stainless steel non-porous roll was 10 cm.
[0091]
(3) Drying process
Next, the organic inorganic hybrid-gel-like ultrafine fibers thus accumulated are dried for 1 hour by a heater set at a temperature of 150 ° C., and an inorganic structure comprising the organic inorganic hybrid-dry gel-like ultrafine fibers. Manufactured. The organic inorganic hybrid-dried gel-like ultrafine fibers constituting the inorganic structure were bonded without using an adhesive at the contact point, and did not generate contaminants. In addition, this inorganic structure was not cracked even when it was bent, and the fibers did not fall off.
[0092]
(4) Sintering process
Next, this inorganic inorganic hybrid-dried gel-like inorganic structure is dried for 1 hour at a temperature of 500 ° C. and completely vitrified to an average fiber diameter of 0.8 μm (any point) An inorganic structure composed of organic inorganic hybrid-sintered ultrafine fibers having a fiber diameter of about 0.8 μm was manufactured. The CV value was 0.29. The organic inorganic hybrid-sintered ultra-thin fibers of this inorganic structure were bonded at the contact point without any adhesive, and did not generate contaminants. In addition, this inorganic structure was not cracked even when it was bent, and the fibers did not fall off.
[0093]
[Comparative Example 1]
Using an E glass chop having an average fiber diameter of 5 μm and a fiber length of 13 mm, an acrylic binder is added to a sheet formed by a wet method using a spray method, and then dried in an oven and crosslinked to form a glass nonwoven fabric (weight per unit: 10 g) / M²Thickness = 90 μm; apparent density = 0.11 g / cm^ThreeBinder ratio = 15% by weight; CV value = 0.11).
When this glass nonwoven fabric was bent, the broken glass fiber fell off.
Moreover, when heat was applied to this glass nonwoven fabric at 400 ° C. for 30 minutes, the mass decreased by 5% or more after heating, and the sheet form could not be maintained. For this reason, it was not heat resistant to generate pollutants. Similarly, although the inorganic sintered structure of Example 5 was heated in the same manner as described above, the reduction rate of mass was 0.2%, the sheet form could be maintained, and the heat resistance was less likely to generate contaminants. It was excellent.
[0094]
【The invention's effect】
According to the method for producing an inorganic structure of the present invention, by drying and / or sintering, an inorganic structure can be produced without using an adhesive, and therefore by using an adhesive. It can prevent harmful effects.
Since the inorganic structure of the present invention has low possibility of fiber dropping and excellent flexibility, it can be deformed into various shapes, can be applied to various uses, and is contaminated with an adhesive. It is difficult to generate substances.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a manufacturing process of an inorganic structure according to the present invention.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 1 ... Sol solution storage part; 21, 22, 23, 24 ... Nozzle;
  3 ... counter electrode; 4 ... support; 5 ... heater;
  6 ... presser roll; 7 ... spinning room;71 ... exhaust port; 8 ... drying chamber;
  9 ... Unwinding roll; 9a, 10a ... Guide roll;
10 ... take-up roll; 30 ... power source; 41, 42, 43 ... roller.

Claims (5)

(1) a step of forming a sol solution mainly composed of inorganic components;
(2) The sol solution is extruded from a nozzle, and is thinned by applying an electric field to the extruded sol solution to form inorganic gel fine fibers, and the inorganic gel fine fibers are accumulated on the support. And (3) drying the accumulated inorganic gel-like fine fibers to form an inorganic structure containing the inorganic dry gel-like fine fibers. Manufacturing method. (1) a step of forming a sol solution mainly composed of inorganic components;
(2) The sol solution is extruded from a nozzle, and is thinned by applying an electric field to the extruded sol solution to form inorganic gel-like fine fibers, and the inorganic gel-like fine fibers are accumulated on the support. And (3) sintering the accumulated inorganic gel-like fine fibers to form an inorganic structure containing the inorganic sintered fine fibers. Manufacturing method. (1) a step of forming a sol solution mainly composed of inorganic components;
(2) The sol solution is extruded from a nozzle, and is thinned by applying an electric field to the extruded sol solution to form inorganic gel-like fine fibers, and the inorganic gel-like fine fibers are accumulated on the support. Process,
(3) drying the accumulated inorganic gel-like fine fibers to form an inorganic structure including inorganic dry gel-like fine fibers; and (4) including the inorganic dry gel-like fine fibers. A method for producing an inorganic structure, comprising a step of sintering an inorganic structure to form an inorganic structure including inorganic sintered fine fibers.   Before the inorganic gel fine fibers reduced in diameter by applying an electric field are accumulated on the support, the organic gel fine fibers, the organic fibers, the inorganic fibers, the organic fibers and / or the Or the manufacturing method of the inorganic structure as described in any one of Claims 1-3 which sprays the thread | yarn consisting of inorganic fiber, or powder.   The method for producing an inorganic structure according to any one of claims 1 to 4, wherein the support has a three-dimensional solid shape.

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