JP4663885B2 - Method for producing alumina-silica fiber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for producing an alumina-silica fiber.To the lawIt is related.
[0002]
[Prior art]
Conventionally, an internal combustion engine using gasoline or light oil as a fuel has been used for more than 100 years as a power source for vehicles, particularly automobiles. However, exhaust gas is harmful to health and the environment. Therefore, recently, various exhaust gas purifying catalytic converters for removing CO, NOx, HC and the like contained in exhaust gas, and various DPFs for removing PM and the like have been proposed. A normal exhaust gas purifying catalytic converter includes a catalyst carrier, a metal shell covering the outer periphery of the catalyst carrier, and a holding sealing material disposed in a gap therebetween. As the catalyst carrier, a cordierite carrier formed in a honeycomb shape is used, and a catalyst such as platinum is supported on the carrier.
[0003]
Recently, research on the next clean power source that does not use oil as a power source has been promoted, and a particularly promising example is a fuel cell. A fuel cell uses electricity obtained when hydrogen and oxygen react to form water as a power source. Oxygen is extracted directly from the air, while hydrogen is reformed from methanol, gasoline, or the like. In this case, reforming of methanol or the like is performed by a catalytic reaction. Also in such a fuel cell, a catalytic converter for a fuel cell including a catalyst carrier, a metal shell covering the outer periphery of the catalyst carrier, and a holding sealing material disposed in a gap therebetween is used. Yes. As the catalyst support, a cordierite carrier formed in a honeycomb shape is used, and a copper-based catalyst is supported on the support.
[0004]
An example of a method for manufacturing the above catalytic converter will be briefly described here.
First, a spinning dope containing an alumina source and a silica source is prepared and discharged from a nozzle, whereby precursor fibers having a predetermined cross-sectional shape are continuously obtained. Next, the precursor fibers obtained by the spinning step are fired to form alumina-silica fibers, and then the alumina-silica fibers are chopped to produce short fibers having a predetermined length. Next, the obtained short fibers are put into a mold and a mat-like fiber assembly is produced. A band-shaped holding sealing material is produced by punching this fiber assembly with a mold. Next, the holding sealing material is wound around the outer peripheral surface of the catalyst carrier, and the catalyst carrier is accommodated in the metal shell in this state. As a result, the catalytic converter is completed.
[0005]
[Problems to be solved by the invention]
By the way, it is known that when the spinning dope is discharged through a nozzle, a phenomenon (ballast effect) occurs in which the spinning dope expands to a size larger than the opening diameter of the nozzle. In addition, when the above-mentioned spinning solution for alumina-silica fiber is used, specifically, the ballast ratio (the maximum diameter D of the expanded spinning solution / nozzle opening diameter d) exceeds 2.3 to 2.4. Is also known.
[0006]
However, in the conventional spinning method having a large ballast ratio, the yarn breakage occurs by drawing with a strong tension during spinning, and it becomes difficult to obtain long fibers. For this reason, there exists a possibility of reducing the production efficiency of a holding sealing material.
[0007]
Moreover, since the obtained precursor fiber does not have a shape similar to the cross-sectional shape of the nozzle and becomes a duller shape, it becomes difficult to give the target cross-sectional shape to the fiber. Therefore, the cross-sectional shape of the fibers becomes uneven, and it becomes difficult to manufacture a holding sealing material with stable quality.
[0008]
  The present invention has been made in view of the above problems, and its purpose is, LongAn object of the present invention is to provide a method for producing an alumina-silica-based fiber that is suitable for producing the above holding sealing material because it can be easily made into a fiber and can impart a desired cross-sectional shape to the fiber.
[0009]
[Means for Solving the Problems]
  In order to solve the above-mentioned problems, in the invention according to claim 1, a spinning process for obtaining precursor fibers by discharging a spinning stock solution containing an aqueous aluminum salt solution, silica sol and an organic polymer from a nozzle, and the precursor fibers A method of producing an alumina-silica-based fiber comprising a sintering step of heating and sintering a fiber, wherein the spinning dope further includes a water-soluble plasticizerGlycol ethersThe gist thereof is a method for producing an alumina-silica-based fiber, characterized in that
[0010]
  The invention described in claim 2 is that, in claim 1, the amount of the plasticizer added is 0.1 wt% to 10 wt%..
[0011]
  ContractClaim3The invention described in 1 includes a spinning step of obtaining a precursor fiber by discharging a spinning stock solution containing an aqueous aluminum salt solution, silica sol and an organic polymer from a nozzle, and a firing step of heating and sintering the precursor fiber. A method for producing an alumina-silica fiber, which is capable of reducing the ballast ratio during nozzle discharge to 2.0 or less.Glycol ethers that are plasticizersThe gist of this is a method for producing an alumina-silica-based fiber, characterized in that is added to the spinning dope.
[0015]
  The “action” of the present invention will be described below.
  Claim1According to the described invention, the plasticizerGlycol ethersAs a result of the decrease in the elastic modulus of the spinning dope, the ballast effect is reduced. Therefore, the discharging behavior of the spinning dope is stabilized during spinning. Therefore, even if the fiber is stretched with a strong tension, the fiber is less likely to break, and the fiber cross-sectional shape is less likely to be dull due to elastic deformation. Further, since the plasticizer is water-soluble, it can be uniformly dispersed in the spinning dope. Therefore, the ballast ratio can be reduced to a substantially constant value, and a fiber having a target diameter and cross-sectional shape can be obtained relatively easily.In addition, by using a glycol ether having a high viscosity as a plasticizer, the elastic modulus of the spinning dope can be reliably reduced even with a relatively small amount. Of course, since glycol ethers are organic matter, they are completely burned out by the end of the firing step and do not remain in the finished alumina-silica fiber.
[0016]
According to the second aspect of the present invention, the ballast effect can be reliably reduced without affecting the physical properties of the alumina-silica fiber by setting the addition amount of the plasticizer within the above preferred range.
[0017]
If the addition amount is less than 0.1% by weight, the elastic modulus is not sufficiently reduced, and various effects due to the addition of the plasticizer may not be expected. On the other hand, if the amount added exceeds 10% by weight, the non-ceramic component ratio in the spinning dope may increase, which may cause the physical properties of the alumina-silica fiber to be affected.
[0020]
  Claim3According to the invention described in the above,Glycol ethers that are plasticizersAs a result, the ballast ratio of the spinning dope is reduced to 2.0 or less, so that the discharge behavior of the spinning dope is stabilized during spinning. Therefore, even if the fiber is stretched with a strong tension, the fiber is less likely to break, and the fiber cross-sectional shape is less likely to be dull due to elastic deformation. Also, abovePlasticizerIs water-soluble and can be uniformly dispersed in the spinning dope. Therefore, the ballast ratio can be reduced to a substantially constant value, and a fiber having a target diameter and cross-sectional shape can be obtained relatively easily.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a catalytic converter for an automobile exhaust gas purification apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS.
[0023]
The catalytic converter 1 of the present embodiment shown in FIG. 3 is provided in the middle of an exhaust pipe of an engine in an automobile body. Since the distance from the engine to the catalytic converter 1 is relatively short, the exhaust gas having a high temperature of about 700 ° C. to 900 ° C. is supplied to the catalytic converter 1. When the engine is a lean burn engine, the catalytic converter 1 is supplied with exhaust gas having a higher temperature of about 900 ° C. to 1000 ° C.
[0024]
As shown in FIG. 3, the catalytic converter 1 according to the present embodiment basically includes a catalyst carrier 2, a metal shell 3 that covers the outer periphery of the catalyst carrier 2, and a gap between the two. The holding sealing material 4 is configured.
[0025]
The catalyst carrier 2 is manufactured using a ceramic material typified by cordierite or the like. The catalyst carrier 2 is a columnar member having a circular cross section. The catalyst carrier 2 is preferably a honeycomb structure having a large number of cells 5 extending along the axial direction. A noble metal catalyst such as platinum or rhodium capable of purifying exhaust gas components is supported on the cell wall. In addition to the cordierite carrier, for example, a honeycomb porous sintered body such as silicon carbide or silicon nitride may be used as the catalyst carrier 2.
[0026]
As the metal shell 3, for example, when a press-fitting method is employed for assembly, a metal cylindrical member having an O-shaped cross section is used. In addition, as a metal material for forming the cylindrical member, a metal excellent in heat resistance and impact resistance (for example, a steel material such as stainless steel) is preferably selected. When a so-called canning method is employed instead of the press-fitting method, a metal cylindrical member having an O-shaped cross section divided into a plurality of pieces along the axial direction (that is, a clam shell) is used.
[0027]
In addition, in the case of adopting a tightening method at the time of assembling, for example, a metal cylindrical member having a C-shaped or U-shaped cross section, in other words, a metal having a slit (opening) extending along the axial direction only at one place. A cylindrical member is used. In this case, when the catalyst carrier 2 is assembled, the catalyst carrier 2 fixed with the holding sealing material 4 is housed in the metal shell 3, and the metal shell 3 is wound in this state, and the opening end is joined ( Welding, bonding, bolting, etc.). Joining operations such as welding, bonding, and bolting are similarly performed when the canning method is adopted.
[0028]
As shown in FIG. 1, the holding sealing material 4 is a long mat-like material, and has a concave mating portion 11 at one end and a convex mating portion 12 at the other end. Yes. As shown in FIG. 2, at the time of winding around the catalyst carrier 2, the convex matching portion 12 is just engaged with the concave matching portion 11.
[0029]
The holding sealing material 4 of the present embodiment is configured with ceramic fibers (that is, fiber aggregates) gathered in a mat shape as main elements. In the present embodiment, alumina-silica fiber 6 is used as the ceramic fiber. In this case, it is more preferable to use alumina-silica fiber 6 having a mullite crystal content of 0 wt% or more and 10 wt% or less. This is because such a chemical composition has excellent heat resistance due to a small amount of amorphous components, and has a high repulsive force when a compressive load is applied. Therefore, even when a high temperature is encountered in the state of being arranged in the gap, the generated surface pressure is relatively less likely to decrease.
[0030]
The chemical composition of the alumina-silica fiber 6 may be 68 wt% to 83 wt% alumina and 32 wt% to 17 wt% silica.₂O_Three: SiO₂It is even better that = 72: 28.
[0031]
When alumina is less than 68% by weight or silica exceeds 32% by weight, the heat resistance and the resilience when applying a compression load may not be sufficiently achieved. Similarly, when alumina exceeds 83% by weight or when silica is less than 17% by weight, there is a possibility that improvement in heat resistance and improvement in repulsive force when a compression load is applied cannot be sufficiently achieved.
[0032]
The average fiber diameter of the alumina-silica fiber 6 is preferably about 3 μm to 25 μm, and more preferably about 10 μm to 20 μm. This is because if the average fiber diameter is too small, there is an inconvenience that it is easily sucked into the respiratory system. The average fiber length of the alumina-silica fiber 6 is preferably about 0.1 mm to 100 mm, more preferably about 2 mm to 50 mm. Further, the tensile strength of the alumina-silica fiber 6 itself is preferably 0.1 GPa or more, particularly 0.5 GPa or more. The cross-sectional shape of the alumina-silica-based fiber 6 may be a perfect circle shape or an irregular cross-sectional shape (for example, an elliptical shape, an oval shape, a substantially triangular shape, etc.).
[0033]
The thickness of the holding sealing material 4 before assembly is about 1.1 to 4.0 times, more preferably 1.5 to 3.0 times the gap between the catalyst carrier 2 and the metal shell 3. It is desirable that the degree. If the thickness is less than 1.1 times, high carrier holding ability cannot be obtained, and the catalyst carrier 2 may be displaced or loose with respect to the metal shell 3. Of course, in this case, since high sealing performance cannot be obtained, the exhaust gas leaks easily from the gap portion, and it becomes impossible to realize high low pollution. If the thickness exceeds 4.0 times, particularly when the press-fitting method is adopted, it becomes difficult to dispose the catalyst carrier 2 on the metal shell 3. Therefore, there is a possibility that the improvement in assemblability cannot be achieved.
[0034]
The GBD (bulk density) of the holding sealing material 4 after assembly is 0.10 g / cm.^Three~ 0.30g / cm^ThreeAnd even 0.10 g / cm^Three~ 0.25g / cm^ThreeIt is preferable to set so that. If the GBD value is extremely small, it may be difficult to achieve a sufficiently high initial surface pressure. On the other hand, if the GBD is too large, the amount of the alumina-silica fiber 6 to be used as a material increases, which tends to increase the cost.
[0035]
The initial surface pressure of the holding sealing material 4 in the assembled state is preferably 50 kPa or more, and more preferably 70 kPa or more. This is because if the value of the initial surface pressure is high, it is possible to maintain a suitable holding property of the catalyst carrier 2 even if the surface pressure is deteriorated with time.
[0036]
The holding sealing material 4 may be subjected to needle punching treatment, resin impregnation treatment, or the like as necessary. This is because the holding sealing material 4 can be compressed in the thickness direction and thinned by performing these treatments.
[0037]
Next, a procedure for manufacturing the catalytic converter 1 will be described.
First, an aqueous solution of aluminum salt, silica sol and an organic polymer are mixed to prepare a spinning dope 8. In other words, the spinning dope 8 is prepared by the inorganic salt method. The aqueous aluminum salt solution that is the alumina source is also a component for imparting viscosity to the spinning dope 8. Note that an aqueous solution of a basic aluminum salt is preferably selected as such an aqueous solution. Silica sol as a silica source is also a component for imparting high strength to the fiber. The organic polymer is a component for imparting spinnability to the spinning dope 8.
[0038]
In the present embodiment, for the purpose of reducing the ballast ratio (D / d) during nozzle discharge to 2.0 or less (desirably 1.8 or less, more desirably 1.4 or less), A water-soluble plasticizer is further added to the spinning dope 8.
[0039]
The amount of the plasticizer added is preferably 0.1% by weight to 10% by weight, and more preferably 0.1% by weight to 3% by weight.
If the addition amount is less than 0.1% by weight, the elastic modulus is not sufficiently reduced, and various effects due to the addition of the plasticizer may not be expected. On the other hand, when the addition amount exceeds 10% by weight, there is a possibility that the physical properties of the alumina-silica fiber 6 may be affected as the non-ceramic component ratio in the spinning dope 8 increases.
[0040]
As the plasticizer, a water-soluble organic substance is preferably selected, and more specifically, a glycol ether having a high viscosity is preferably selected. This is because this kind of organic substance can surely reduce the elastic modulus of the spinning dope 8 even with a relatively small amount. Moreover, if it is glycol ether, it is because it will burn out completely by heat until the baking process implemented after a spinning process is completed.
[0041]
Here, glycol ethers usable as a plasticizer are listed, for example, tetraethylene glycol monobutyl ether (3,6,9,12-tetraoxahexadecanol), triethylene glycol monobutyl ether (3,6,9). -Trioxatridecanol), diethylene glycol monobutyl ether (2- (2-butoxyethoxy) ethanol), propylene glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether (1-methoxy-2-propanol), propylene glycol monomethyl And mixtures of ether acetate and acetic acid. In addition to the above glycol ethers, viscous organic substances such as polyethylene glycol and glycerin can also be used as the plasticizer. In addition, only one kind of the organic substances listed here may be added to the spinning dope 8, or two or more kinds may be added in combination.
[0042]
In addition, an antifoaming agent or the like may be added to the spinning dope 8. The chemical composition of the alumina-silica fiber 6 can be controlled to some extent by changing the ratio of the aluminum salt and silica sol.
[0043]
Next, the obtained spinning dope 8 is concentrated under reduced pressure to obtain a spinning dope 8 adjusted to a concentration, temperature, viscosity, etc. suitable for spinning. Here, the spinning dope 8 that was about 20% by weight is preferably concentrated to about 30% to 40% by weight. Moreover, it is good to set a viscosity to 10 poise-2000 poise.
[0044]
Further, when the prepared spinning solution 8 is discharged into the air from the nozzle 9 of the spinning device 10, precursor fibers 6A having a cross-sectional shape similar to the opening shape of the nozzle 9 are continuously obtained. The precursor fibers 6A spun in this way are sequentially wound while being drawn. In this case, for example, a dry pressure spinning method is preferably employed.
[0045]
Next, the precursor fiber 6A is cured by calcination to crystallize (crystallize) the precursor fiber 6A, whereby the alumina-silica fiber 6 is obtained. The plasticizer is completely burned off by the heat at this time, and hardly remains in the alumina-silica fiber 6.
[0046]
In the firing step, it is desirable to set firing conditions such that the mullite crystal content in the resulting alumina-silica fiber 6 is 10% by weight or less. For example, the firing temperature in the firing step is preferably set to 1000 ° C to 1300 ° C. When the firing temperature is less than 1000 ° C., the precursor fiber 6A cannot be completely dried and sintered, and excellent heat resistance and a repulsive force when a high compressive load is applied can be reliably imparted to the holding sealing material 4. There is a risk of disappearing. On the other hand, when the firing temperature exceeds 1300 ° C., mullite crystallization in the alumina-silica fiber 6 tends to proceed. For this reason, it becomes difficult to suppress the mullite crystal content to 10% by weight or less, and it may not be possible to reliably impart excellent heat resistance and repulsive force when a high compressive load is applied to the holding sealing material 4.
[0047]
Subsequently, the long fibers of the alumina-silica fibers 6 obtained through the above-described steps are chopped to a predetermined length to shorten the fibers to some extent. Thereafter, by collecting, defibrating and laminating short fibers, or by pouring a fiber dispersion obtained by dispersing short fibers into water into a mold and drying them, the mat-like A fiber assembly is obtained. Further, this fiber assembly is punched into a predetermined shape to form a holding sealing material 4.
[0048]
Thereafter, the holding sealing material 4 may be further compression-molded in the thickness direction after impregnating the holding sealing material 4 with an organic binder as necessary. Examples of the organic binder in this case include latex such as acrylic rubber and nitrile rubber, polyvinyl alcohol, acrylic resin, and the like.
[0049]
Then, the holding sealing material 4 obtained by punching the fiber assembly into a predetermined shape is wound around the outer peripheral surface of the catalyst carrier 2 to fix the organic tape 13. Thereafter, press-fit, canning or winding is performed to complete the desired catalytic converter 1.
[0050]
Hereinafter, examples and comparative examples of the above embodiment will be described.
[0051]
[Examples and Comparative Examples]
Example 1
In Example 1, a sample for evaluating the surface pressure of the holding sealing material 4 was produced as follows.
[0052]
First, a basic aluminum chloride aqueous solution (23.5 wt%), silica sol (20 wt%, silica particle size 15 μm), polyvinyl alcohol (10 wt%) and tetraethylene glycol monobutyl ether (1 wt%) are mixed and spun. Stock solution 8 was prepared. Next, the obtained spinning dope 8 was concentrated under reduced pressure at 50 ° C. using an evaporator to prepare a spinning dope 8 having a concentration of 38% by weight and a viscosity of 1500 poise. When the elastic modulus of the spinning dope 8 at this time was measured by a dynamic viscoelasticity measuring method, 1.0 × 10^5.5dyne / cm²Met.
[0053]
The prepared spinning stock solution 8 was continuously ejected into the air from the nozzle 9 (opening diameter: 500 μm, cross-sectional perfect circle shape) of the spinning device 10, and the formed precursor fiber 6A was wound up while being stretched. At this time, the maximum diameter of the spinning dope 8 expanded immediately after discharge was about 600 μm. Therefore, the ballast ratio in the present example was an extremely small value of about 1.2, and it was found that the ballast effect was reliably reduced. Moreover, when spinning was carried out for about 1 hour, no yarn breakage occurred during that time, and continuously long precursor fibers 6A could be stably obtained.
[0054]
Next, the precursor fiber 6A was heated at 250 ° C. for 30 minutes (pretreatment) in an electric furnace maintained in an air atmosphere, and then baked at 1250 ° C. for 10 minutes in the same electric furnace. .
[0055]
As a result, a perfect circular alumina-silica fiber 6 having a mullite crystal content of about 8% by weight, an alumina / silica weight ratio of 72:28, and an average fiber diameter of 9 μm was obtained. When the obtained alumina-silica-based fiber 6 was observed, it could be said that the diameter and the cross-sectional shape were uniform and the quality was extremely stable. Moreover, the organic substance was hardly contained in the component of the alumina-silica-based fiber 6.
[0056]
Subsequently, the long fibers of the alumina-silica fiber 6 were chopped to a length of 5 mm to make short fibers. Thereafter, the short fibers were dispersed in water, and the resulting fiber dispersion was poured into a forming mold and pressed and dried to obtain a mat-like fiber aggregate. The fiber assembly was punched into a predetermined shape to produce a holding sealing material 4, which was then wound around the catalyst carrier 2 and pressed into the metal shell 3. As the catalyst carrier 2, a cordierite monolith having an outer diameter of 130 mmφ and a length of 100 mm was used. As the metal shell 3, a cylindrical member made of SUS304 having a wall thickness of 1.5 mm, an inner diameter of 140 mmφ, and an O-shaped cross section was used. A test was conducted in which the catalytic converter 1 thus assembled was actually mounted on a 3-liter gasoline engine and continuously operated. As a result, it was found that no abnormal noise was generated during running and no backlash of the catalyst carrier 2 was observed, and a high initial surface pressure was applied.
(Examples 2 to 6)
In Examples 2, 3, and 4, the addition amount of tetraethylene glycol monobutyl ether as a plasticizer was set to 0.2% by weight, 2% by weight, and 5% by weight, respectively.
Then, a spinning dope 8 was prepared according to Example 1.
[0057]
In Example 5, propylene glycol monobutyl ether was selected as a plasticizer instead of tetraethylene glycol monobutyl ether, and 1.5% by weight thereof was added. Then, a spinning dope 8 was prepared according to Example 1.
[0058]
In Example 6, polyethylene glycol was selected as a plasticizer instead of tetraethylene glycol monobutyl ether, and 3% by weight thereof was added.
Then, a spinning dope 8 was prepared according to Example 1.
[0059]
When the elastic modulus at this time was measured for the spinning dope 8 of each of the above Examples 2 to 6, it was about 1.0 × 10^5.5dyne / cm²~ 1.0 × 10^5.8dyne / cm²Met.
[0060]
Subsequently, spinning was performed under the same conditions as in Example 1. As a result, the value of the ballast ratio was about 1.2 in Examples 3, 4, 5, and 6, and about 1.5 in Example 2. Therefore, it was found that the ballast effect was reliably reduced in all cases as in Example 1. Moreover, when spinning was carried out for about 1 hour, no yarn breakage occurred during that time, and continuously long precursor fibers 6A could be stably obtained.
(Comparative example)
In the comparative example, first, a basic aluminum chloride aqueous solution (23.5 wt%), silica sol (20 wt%, silica particle size 15 μm) and polyvinyl alcohol (10 wt%) were mixed to prepare a spinning dope 8. That is, the above plasticizer was not added here. Next, the obtained spinning dope 8 was concentrated under reduced pressure at 50 ° C. using an evaporator to prepare a spinning dope 8 having a concentration of 38% by weight and a viscosity of 1500 poise. When the elastic modulus of the spinning dope 8 at this time was measured, it was 1.0 × 10^6.4dyne / cm²The value was somewhat higher than in each example.
[0061]
When spinning was performed using the prepared spinning stock solution 8 under the same conditions as in Example 1, the maximum diameter of the spinning stock solution 8 expanded immediately after discharge was about 1200 μm. Therefore, it was found that the ballast ratio in the comparative example was an extremely large value of about 2.4. In addition, since yarn breakage frequently occurs during spinning, it was impossible to stably obtain a long precursor fiber 6A continuously. Therefore, in order to prevent yarn breakage, the tension at the time of drawing has to be set weak, and the production efficiency is poor.
[0062]
Next, after firing and producing the alumina-silica fiber 6, this was observed. As a result, the diameter and the cross-sectional shape were uneven, and the quality was unstable.
[0063]
Therefore, according to the present embodiment, the following effects can be obtained.
(1) The present embodiment is characterized in that a water-soluble plasticizer is added in advance to the spinning dope 8 and spinning is performed using the spinning dope 8. For this reason, the elastic modulus of the spinning dope 8 can be reduced, and the ballast effect can be reliably reduced. Therefore, the discharge behavior of the spinning dope 8 is stabilized during spinning. Therefore, breakage of the precursor fiber 6A is less likely to occur even when stretching is performed with a strong tension. In addition, the fiber cross-sectional shape is less likely to be blunted by elastic deformation. Further, since the plasticizer is water-soluble, it can be uniformly dispersed in the spinning dope. Therefore, the ballast ratio can be reduced to a substantially constant value, and a fiber having a target diameter and cross-sectional shape can be obtained relatively easily.
[0064]
From the above, according to this spinning method, it is not necessary to set the tension at the time of drawing weakly in order to prevent yarn breakage, and the spinning efficiency is surely improved, so that the holding sealing material 4 can be produced efficiently. Can do. In addition, since it is possible to obtain alumina-silica fibers having a uniform cross-sectional shape, it is possible to obtain the holding sealing material 4 that is stable in quality.
[0065]
(2) In this embodiment, the addition amount of the plasticizer is set within a range of 0.1 wt% to 10 wt%. Accordingly, it is possible to reliably reduce the ballast effect without affecting the physical properties of the alumina-silica fiber 6 (that is, causing a decrease in strength and heat resistance). Therefore, the quality of the holding sealing material 4 can be further improved.
[0066]
(3) In this embodiment, a viscous organic material typified by glycol ethers is used as a plasticizer. Even if a predetermined amount of this kind of organic matter is added to the spinning dope 8, it is completely burned out by the end of the firing step, and therefore does not remain in the finished alumina-silica fiber 6. Accordingly, the physical properties of the alumina-silica-based fiber 6 are not affected, and suitable physical properties comparable to those without additives can be imparted to the fibers. Further, if the plasticizer having a high viscosity is used, the elastic modulus of the spinning dope 8 can be reliably reduced even with a relatively small amount.
[0067]
In addition, you may change embodiment of this invention as follows.
-It is permitted to reduce the ballast ratio by a method other than the method of adding a water-soluble substance to the spinning dope 8.
[0068]
The cross-sectional shape of the catalyst carrier 2 is not limited to a perfect circle, and may be, for example, an ellipse or an ellipse. In this case, the cross-sectional shape of the metal shell 3 may be changed to an elliptical shape or an oval shape in accordance with it.
[0069]
As the catalyst carrier 2, a cordierite carrier formed into a honeycomb shape as in the embodiment may be used, and for example, a honeycomb porous sintered body such as silicon carbide or silicon nitride may be used.
[0070]
In the embodiment, an example in which the holding sealing material 4 of the present invention is used for the catalytic converter 1 for an exhaust gas purification device has been described. Of course, the holding sealing material 4 of the present invention is allowed to be used in other than the exhaust gas purifying device catalytic converter 1, such as a diesel particulate filter (DPF), a fuel cell reformer catalytic converter, and the like.
[0071]
Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiment described above are listed below.
(1) A method for lengthening an alumina-silica-based fiber by obtaining a precursor fiber by discharging a spinning stock solution containing an aluminum salt aqueous solution, silica sol and an organic polymer from a nozzle, which is further soluble in the spinning stock solution. A method for lengthening an alumina-silica fiber, comprising adding a plasticizer (or a water-soluble substance capable of reducing the ballast ratio during nozzle discharge to 2.0 or less). Therefore, according to the invention described in this technical idea 1, it is possible to continuously obtain long fibers while imparting the intended cross-sectional shape to the fibers.
[0072]
(2) A spinning method of alumina-silica fiber in which a spinning stock solution containing an aluminum salt aqueous solution, silica sol and an organic polymer is discharged from a nozzle, and the ballast ratio is reduced to 2.0 or less when discharging the nozzle. A method for spinning an alumina-silica fiber, characterized by performing a treatment. Therefore, according to the invention described in this technical idea 2, it is easy to make a long fiber, and a desired cross-sectional shape can be imparted to the fiber.
[0073]
(3) A spinning method of alumina-silica fiber in which a spinning stock solution containing an aluminum salt aqueous solution, silica sol and an organic polymer is discharged from a nozzle, wherein a water-soluble elastic modulus reducing agent is added to the spinning stock solution. A method for producing an alumina-silica-based fiber. Therefore, according to the invention described in the technical idea 3, it is easy to make long fibers, and it is possible to impart a desired cross-sectional shape to the fibers.
[0074]
【The invention's effect】
  As detailed above, claims 1 to3According to the invention described in (1), it is easy to make a long fiber, and a desired cross-sectional shape can be given to the fiber. For this reason, the manufacturing method of the alumina- silica type fiber suitable for manufacture of a holding sealing material can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view of a holding seal material for a catalytic converter according to an embodiment of the present invention.
FIG. 2 is a perspective view for explaining a manufacturing process of the catalytic converter of the embodiment.
FIG. 3 is a partial cross-sectional view of the catalytic converter of the embodiment.
FIG. 4 is a schematic cross-sectional view of a nozzle portion in the spinning device of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Catalytic converter, 2 ... Catalyst support body, 3 ... Metal shell, 4 ... Holding seal material for catalytic converters, 5 ... Gap, 6 ... Alumina-silica fiber as ceramic fiber, 6A ... Precursor fiber, 8 ... Spinning stock solution, 9 ... Nozzle.

Claims (3)

  An alumina-silica-based fiber comprising a spinning step of obtaining a precursor fiber by discharging a spinning stock solution containing an aluminum salt aqueous solution, silica sol and an organic polymer from a nozzle, and a firing step of heating and sintering the precursor fiber A method for producing an alumina-silica-based fiber, wherein glycol ethers, which are water-soluble plasticizers, are further added to the spinning dope.   The method for producing an alumina-silica fiber according to claim 1, wherein the plasticizer is added in an amount of 0.1 wt% to 10 wt%. An alumina-silica-based fiber comprising: a spinning process in which a spinning stock solution containing an aluminum salt aqueous solution, silica sol and an organic polymer is discharged from a nozzle to obtain a precursor fiber; and a firing process in which the precursor fiber is heated and sintered. An alumina-silica-based fiber, which is a production method, wherein glycol ethers, which are water-soluble plasticizers capable of reducing the ballast ratio during nozzle discharge to 2.0 or less, are added to the spinning dope Manufacturing method .

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