JP2018009262A - Inorganic fiber compact and production process and apparatus thereof, and mat for exhaust gas rinsing apparatus and exhaust gas rinsing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber compact high in inter layer peeling strength, a production process and apparatus thereof, a mat for an exhaust gas rinsing apparatus using the inorganic fiber compact and the exhaust gas rinsing apparatus.SOLUTION: An inorganic fiber compact consists of mat-like aggregate 1 of inorganic fiber, and has needle traces extending in a direction including the thickness direction of the mat-like aggregate. At the needle trace, at least one part of the fiber is connected with each other in a spiral. At the needle trace 2, the fiber is connected with each other in a spiral by pricking a needle 30 to the mat-like aggregate while rotating the needle around the central axis.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a needled inorganic fiber molded body and a method and apparatus for producing the same. The present invention also relates to an exhaust gas cleaning mat composed of the inorganic fiber molded body, that is, a holding material for a catalyst carrier of the exhaust gas cleaning device and an exhaust gas cleaning device including the exhaust gas cleaning device mat.

  Inorganic fiber molded bodies represented by ceramic fibers have been used for applications exposed to high-temperature conditions such as industrial heat insulating materials, refractory materials, packing materials, etc., but in recent years, cushions for exhaust gas cleaning devices for automobiles. When the material (catalyst gripping material), that is, the catalyst carrier is accommodated in the metal casing, it is also used as an exhaust gas cleaning mat wound around the catalyst carrier and interposed between the catalyst carrier and the metal casing. ing.

  In such an inorganic fiber molded body, for example, when processing as a heat insulating material or when processing into a catalyst gripping material (mat) for automobiles, a needle for punching and piercing a needle is used to control the thickness and surface density. A ring process (needle punch process) is generally performed. Needle puncture marks (needle marks) are generated on the needling-treated mat.

  Patent Document 1 describes a needling device shown in FIG. In Patent Document 1, the needling is referred to as needle punching, and the inorganic fiber molded body is referred to as web.

  As shown in FIG. 2 (cross-sectional view seen from the direction along the conveyance direction of the web W1; the web W1 is indicated by a virtual line), the needle punching device 5 receives a driving force in the vertical direction from a driving source. A needle board 51 capable of reciprocating in the needle piercing direction (vertical direction) and a pair of support plates 52 and 53 facing both the front and back surfaces of the web W1 are provided. The support plates 52 and 53 are formed with needle insertion openings 52a and 53a, respectively.

  A large number of needles 54, 54,... For piercing the web W1 are fixed to the lower surface of the needle board 51. In the vicinity of the tip of each needle 54, 54,..., A “return” for hooking a part of the inorganic fibers when stabbed into the web W 1 is formed. In the first needle punching device 5, these needles 54, 54,... Are arranged at equal intervals in the horizontal direction orthogonal to the conveying direction of the web W1. In addition, a plurality of sets of needle rows that are arranged at equal intervals in the horizontal direction orthogonal to the conveyance direction of the web W1 may be arranged across the conveyance direction of the web W1.

  In the needle punching process by the first needle punching device 5, the web W1 is passed between the support plates 52 and 53 and the needle board 51 is reciprocated in the vertical direction by a driving device (not shown). The needles 54, 54,... Pierce the web W1, and the fibers in the web W1 are entangled with each other. That is, the needle punching operation of piercing each needle 54, 54,... Into the web W1 by the lowering of the needle board 51 (lowering to the position shown in FIG. 3), and after the needle board 51 moves up, the web W1 is moved by a predetermined distance. By alternately repeating the web feeding operation, the needle punching process is uniformly performed over the entire web W1, and the inorganic fiber mat (web W2) is formed into a rectangular shape. The feed amount per web feed operation at this time coincides with the interval (needle pitch) between the needles 54 and 54, for example.

JP2007-162583

  In the conventional needling process, as shown in FIG. 2, the needle is simply inserted into the inorganic fiber molded body.

  INDUSTRIAL APPLICABILITY The present invention relates to a method and apparatus for manufacturing an inorganic fiber molded body that can promote entanglement between inorganic fibers by inserting a needle while rotating the needle around its axis, and an inorganic material in which entanglement of inorganic fibers is promoted. An object of the present invention is to provide a fiber molded body, a mat for an exhaust gas cleaning apparatus using the inorganic fiber molded body, and an exhaust gas cleaning apparatus.

  The inorganic fiber molded body of the present invention is an inorganic fiber molded body that is composed of a mat-like aggregate of inorganic fibers and has needle marks extending in a direction including the thickness direction of the mat-like aggregate. The fibers of the part are intertwined in a spiral shape.

  The method for producing an inorganic fiber molded body according to the present invention is a method for manufacturing the inorganic fiber molded body according to the present invention, and includes a needling step of inserting the needle into a mat-like assembly while rotating the needle around its axis. .

  The inorganic fiber molded body manufacturing apparatus of the present invention is characterized in that, in the inorganic fiber molded body manufacturing apparatus having a needle for piercing a mat-like assembly, the needle rotates at the time of piercing.

  A manufacturing apparatus according to an aspect of the present invention is an apparatus for manufacturing an inorganic fiber molded body in which a needle is rotatable about its axis, and the needle is provided with a spiral groove, and the needle is rotated on its axis. A needle board that holds the needle pivotably and reciprocates in the axial direction of the needle, a support plate that has a needle insertion hole through which the needle is inserted, and protrudes from the inner surface of the needle insertion hole And a guide engaged with the spiral groove of the needle.

  The mat for an exhaust gas cleaning apparatus of the present invention is characterized by including the inorganic fiber molded body of the present invention.

  The exhaust gas cleaning apparatus of the present invention includes a catalyst carrier, a casing that covers the outside of the catalyst carrier, and a mat for the exhaust gas cleaning apparatus of the present invention interposed between the catalyst carrier and the casing. .

  In the inorganic fiber molded body of the present invention, since the inorganic fibers are spirally entangled in the needle marks, the delamination strength is high.

  Such an inorganic fiber molded body of the present invention can be easily manufactured by the manufacturing method and apparatus of the present invention.

It is sectional drawing which shows a part of manufacturing apparatus of the inorganic fiber molded object which concerns on embodiment. It is sectional drawing of the apparatus of patent document 1. FIG. It is a side view of an inorganic fiber molded object. It is a photograph which shows the fiber structure of the needle mark of the inorganic fiber molded object which concerns on embodiment. It is a photograph which shows the fiber structure of the needle mark of the inorganic fiber molded object which concerns on a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail.

  The inorganic fiber molded body of the present invention is an inorganic fiber molded body composed of a mat-like aggregate of inorganic fibers and subjected to needling treatment.

  The inorganic fiber molded body of the present invention has needle marks formed by needling treatment. That is, when a needling process for punching and piercing the needle into the mat-like assembly is performed, at least a part of the fibers extend in the mat thickness direction by the needle at the portion where the needle is punched and pierced. A scar is formed.

  In the inorganic fiber molded body of the present invention, the entanglement of the fibers is promoted by rotating the needle around its axis when the needle is inserted.

  FIG. 1 is a partial cross-sectional view of an inorganic fiber molded body manufacturing apparatus (needling apparatus) according to the present invention.

  As in the needle punching apparatus of FIG. 2, this inorganic fiber molded body manufacturing apparatus receives a vertical driving force from a driving source and can reciprocate in the needle piercing direction (vertical direction), and an inorganic fiber mat. A pair of support plates 52 and 53 (53 is not shown in FIG. 1) facing both the front and back surfaces of a web-like assembly (web). These support plates 52 and 53 are formed with needle insertion openings 52a and 53a (53a not shown in FIG. 1), respectively.

  In this embodiment, the needle board 51 is configured to rotatably hold the head 31 of the needle 30 by the two boards 10 and 20. The head 31 of the needle 30 has an abacus ball shape, and has a conical surface 31a on the upper surface side and a conical surface 31b on the lower surface side. The head portion 31 is provided at the upper end of a cylindrical thin rod-like needle body 32. A spiral groove 33 is provided on the outer peripheral surface of the needle body 32. The diameter of the needle body 32 is usually about 1.0 to 3.0 mm.

  The needle 30 is not particularly limited as long as at least a part of the fibers can be spirally entangled in the needle mark, but for example, in addition to a general felting needle, the tip structure Examples include fork needles and crown needles having characteristics, conical blade needles having characteristics of blades, multi-type needles, and compact barb needles.

  Even if one or more “returns” (may be referred to as barbs, not shown) are formed near the tip of the needle 30 to hook some of the inorganic fibers when stabbed into the mat-like assembly. Good. Examples of the shape of the barb include KV barb, HL barb, and RF barb, although there are no particular restrictions on the presence or absence of kick-up and the width and shape of the bottom surface that characterize the shape of the barb.

  Hereinafter, the needle 30 will be described as a needle having a barb (hereinafter sometimes referred to as a barb needle).

  A conical recess 11 that engages with the conical surface 31 a is provided on the lower surface of the board 10, and a conical recess 21 that engages with the conical surface 31 b is provided on the upper surface of the board 20. Liners 12 and 22 made of a highly slidable solid lubricating material such as boron nitride are provided on the inner surfaces of the recesses 11 and 21. The head 31 is rotatably held on the boards 10 and 20 via the liners 12 and 22. The needle body 32 extends downward through a hole 23 provided in the board 20. A liner 24 made of a highly slidable solid lubricating material is provided on the inner peripheral surface of the hole 23.

  A support plate 52 is provided below the needle board 51 in parallel with the needle board 51. An opening 52a for inserting the needle 30 is provided in the support plate 52 in the vertical direction. A cylindrical liner 40 made of a highly slidable solid lubricating material is also provided on the inner surface of the opening (needle insertion hole) 52a of the support plate 52.

  A cylindrical holding hole 41 is recessed in the inner surface of the opening 52a in a direction orthogonal to the axial direction of the opening 52a. A cylindrical guide 42 that can protrude from the holding hole 41 is inserted into the holding hole 41. A coil spring 43 is disposed in the holding hole 41. The coil spring 43 urges the guide 42 in a direction protruding from the holding hole 41. The tip of the guide 42 is engaged with the spiral groove 33 through a small hole in the liner 40.

  Also in this needling device, the needle board 51 is pierced into the mat-like aggregate by reciprocating the needle board 51 in the vertical direction, and the needling is performed. In this embodiment, since the guide 42 is engaged with the spiral groove 33 of the needle body 32, when the needle board 51 is moved downward, simultaneously when the needle 30 is moved downward, the tip of the needle 30 is returned. As the needle 30 is engaged with the inorganic fiber, the needle 30 advances while rotating around its axis (clockwise in the embodiment of FIG. 1). Thereby, the inorganic fibers in the mat-like aggregate are spirally entangled in the needle marks, and the delamination strength of the mat-like aggregate becomes high. When the needle board 51 moves upward, the needle 30 simultaneously moves upward while rotating in the direction opposite to the rotating direction when it is downward (counterclockwise in the embodiment of FIG. 1). Thereby, the inorganic fiber engaged with the return of the needle in the needle mark is separated from the return of the needle while maintaining the spirally entangled state.

  The needling condition is not particularly limited, but the needling is performed while the needle 30 rotates by 0.5 to 3.0 before the return of the needle at the tip of the needle 30 penetrates the mat-like assembly. It is preferable to do. By performing needleing while the needle 30 is rotated by 0.5 or more before the return of the needle at the forefront of the needle 30 penetrates the mat-like assembly, inorganic fibers entangled in a spiral shape in the needle mark can be formed. On the other hand, the needle 30 rotates by 3.0 or less before the return of the needle at the forefront of the needle 30 penetrates the mat-like assembly, so that the inorganic fibers entangled in a spiral shape are destroyed. It is kept without.

  The above-mentioned needling conditions describe that the needle 30 is a barb needle. However, in the case of a fork needle, the return of the most advanced needle may be read as the most advanced fork shape.

  In addition, a total of 1.5 needles are used until a needle having a diameter of 1.8 mm passes through the mat-like assembly until the most advanced needle returns to the mat-like assembly (alumina fiber precursor mat) 1 having a thickness t = 30 mm. The needle was pierced while rotating. FIG. 4 shows a photograph (magnification 30 times) of the mat-like assembly 1 taken as shown in FIG. As shown in FIG. 4, in this needle mark 2, the fibers are intertwined in a spiral shape to form a tornado shape.

  The rotational movement of the needle is not limited to the method described above, and may be a drive type using a motor, for example.

  FIG. 5 shows a needle mark formed by piercing the mat-like assembly 1 without rotating the needle. In the needle marks in this case, the fibers are looped. There is no spiral entanglement of the fibers.

  In the present invention, the needle marks may be perpendicular to the mat surface, and may be obliquely crossed within a range of ± 75 ° with respect to the direction perpendicular to the mat surface.

  Hereinafter, the inorganic fiber etc. which comprise the inorganic fiber molded object of this invention are demonstrated.

<Inorganic fiber>
The inorganic fiber constituting the inorganic fiber molded body of the present invention is not particularly limited, and examples thereof include silica, alumina / silica, zirconia containing these, spinel, titania alone, or composite fibers. Alumina / silica fibers, especially crystalline alumina / silica fibers. The composition ratio (weight ratio) of alumina / silica of the alumina / silica fiber is preferably in the range of 60 to 95/40 to 5, more preferably in the range of 70 to 74/30 to 26.

  The average fiber diameter of the inorganic fibers is preferably 3 to 10 μm, particularly preferably 5 to 8 μm. If the average fiber diameter of the inorganic fiber is too large, the repulsive force of the fiber assembly is lost, and if it is too thin, the amount of dust that floats in the air increases.

<Area density>
The surface density (mass per unit area) of the inorganic fiber molded body of the present invention is appropriately determined according to the use, but is usually about 400 to 3000 g / m ² .

<Method for producing inorganic fiber molded body>
The method for producing the inorganic fiber molded body of the present invention is not particularly limited, but usually, a step of obtaining a mat-like aggregate of inorganic fiber precursors by a sol-gel method, and a mat-like aggregate of the obtained inorganic fiber precursors And a step of subjecting the body to the needling treatment described above. In this method, after the needling treatment, a firing step is performed by firing the mat-like aggregate of the inorganic fiber precursor subjected to the needling treatment to form a mat-like aggregate of inorganic fibers.

  Hereinafter, the method for producing an inorganic fiber molded body of the present invention will be described by exemplifying a method for producing an alumina / silica-based fiber molded body. However, the inorganic fiber molded body of the present invention is not limited to an alumina / silica-based fiber molded body. Without limitation, as described above, a molded body made of silica, zirconia, spinel, titania or a composite fiber thereof may be used.

{Spinning process}
In order to produce a mat-like aggregate of alumina / silica fibers by the sol-gel method, first, a spinning solution containing basic aluminum chloride, a silicon compound, an organic polymer as a thickener, and water is blown. Spinning to obtain an aggregate of alumina / silica fiber precursors.

[Preparation of spinning solution]
Basic aluminum _{chloride; Al (OH) 3-x} Cl x , for example, can be prepared by dissolving aluminum metal in hydrochloric acid or aluminum chloride solution. The value of x in the above chemical formula is usually 0.45 to 0.54, preferably 0.5 to 0.53. Silica sol is preferably used as the silicon compound, but water-soluble silicon compounds such as tetraethyl silicate and water-soluble siloxane derivatives can also be used. As the organic polymer, for example, water-soluble polymer compounds such as polyvinyl alcohol, polyethylene glycol, and polyacrylamide are preferably used. These polymerization degrees are 1000-3000 normally.

In the spinning solution, the ratio of aluminum derived from basic aluminum chloride and silicon derived from silicon compound is usually 99: 1 to 65:35, preferably 99: 1, in terms of the weight ratio of Al ₂ O ₃ and SiO _2. It is preferable that the concentration of aluminum is 170 to 210 g / L and the concentration of the organic polymer is 20 to 50 g / L.

When the amount of the silicon compound in the spinning solution is less than the above range, the alumina constituting the short fiber is easily converted to α-alumina, and the short fiber is easily embrittled due to coarsening of the alumina particles. On the other hand, when the amount of the silicon compound in the spinning solution is larger than the above range, the amount of silica (SiO ₂ ) produced together with mullite (3Al ₂ O ₃ .2SiO ₂ ) increases, and the heat resistance tends to decrease.

  When the concentration of aluminum in the spinning solution is less than 170 g / L or the concentration of the organic polymer is less than 20 g / L, the alumina / silica fiber is obtained without obtaining an appropriate viscosity of the spinning solution. The fiber diameter becomes smaller. That is, as a result of too much free water in the spinning solution, the drying speed during spinning by the blowing method is slow, the drawing progresses excessively, the fiber diameter of the spun precursor fiber changes, and at a predetermined average fiber diameter In addition, short fibers having a sharp fiber diameter distribution cannot be obtained. Moreover, when the aluminum concentration is less than 170 g / L, productivity is lowered. On the other hand, when the aluminum concentration exceeds 210 g / L or the organic polymer concentration exceeds 50 g / L, the viscosity is too high to be a spinning solution. The preferable concentration of aluminum in the spinning solution is 180 to 200 g / L, and the preferable concentration of the organic polymer is 30 to 40 g / L.

The above spinning solution is prepared by adding the silicon compound and the organic polymer in an amount corresponding to the Al ₂ O ₃ : SiO ₂ ratio to the basic aluminum chloride aqueous solution so that the concentrations of the aluminum and the organic polymer are in the above range. Prepared by concentrating.

[spinning]
Spinning (spinning of the spinning solution) is usually performed by a blowing method in which the spinning solution is supplied into a high-speed spinning air stream, whereby an alumina short fiber precursor is obtained. The structure of the spinning nozzle used in the above spinning is not particularly limited. For example, as described in Japanese Patent No. 2602460, the air flow blown from the air nozzle and the spinning liquid supply nozzle are pushed out. The spinning liquid flow is preferably a parallel flow, and the parallel air flow is sufficiently rectified to come into contact with the spinning liquid.

  In spinning, it is preferable that a sufficiently stretched fiber is first formed from the spinning solution under conditions where evaporation of moisture and decomposition of the spinning solution are suppressed, and then the fiber is quickly dried. . For this purpose, it is preferable to change the atmosphere from a state in which the evaporation of moisture is promoted to a state in which the evaporation of moisture is promoted in the process from the formation of fibers from the spinning solution to the arrival of the fiber collector.

  The aggregate of alumina / silica-based fiber precursor includes an endless belt made of wire mesh so as to be substantially perpendicular to the spinning air flow, and the alumina / silica-based fiber precursor is contained in the endless belt while rotating the endless belt. It can be recovered as a continuous sheet (thin layer sheet) by an accumulator having a structure in which the spinning airflow collides.

  The thin-layer sheet collected from the stacking device is continuously drawn out, sent to the folding device, folded into a predetermined width and stacked, and continuously moved in a direction perpendicular to the folding direction into a laminated sheet. can do. Thereby, since it arrange | positions inside a thin layer sheet | seat, the fabric weight of a lamination sheet becomes uniform over the whole sheet | seat. As said folding apparatus, the thing of Unexamined-Japanese-Patent No. 2000-80547 can be used.

{Needling process}
The mat-like aggregate of alumina / silica fiber precursor obtained by spinning is then subjected to the above-mentioned needling treatment. The direction of the needling process may be a process from only one side of the mat or a process from both sides. Preferably, it is a process from both sides.

{Baking process}
Firing after the needling treatment is usually performed at a temperature of 900 ° C. or higher, preferably 1000 to 1300 ° C. When the firing temperature is less than 900 ° C., only weak alumina / silica fibers having low strength can be obtained because of insufficient crystallization, and when the firing temperature exceeds 1300 ° C., the crystal grain growth of the fibers proceeds. Only weak alumina / silica fibers with low strength can be obtained.

  There is no restriction | limiting in particular as a use of the inorganic fiber molded object of this invention, Although there exist various heat insulating materials, packing, etc., it is especially useful as a mat | matte for exhaust gas cleaning apparatuses.

  A mat such as an exhaust gas cleaning apparatus mat does not contain an organic binder, or even if it contains an organic binder, its content is preferably less than 10% by weight.

When the content of the organic binder in the mat is 10% by weight or more, decomposition of the organic binder due to high heat of exhaust gas during engine combustion increases the problem of generation of decomposition gases such as NO _x , CO, and HC, which is not preferable. .

  When an organic binder is used in the mat of the present invention, various rubbers, water-soluble polymer compounds, thermoplastic resins, thermosetting resins, and the like can be used as the organic binder.

  An aqueous solution, water-dispersed emulsion, latex, or organic solvent solution containing the above organic binder as an active ingredient is commercially available. These organic binder liquids can be used as they are or diluted with water, etc. It can be suitably used to contain an organic binder therein. In addition, the organic binder contained in the mat does not necessarily need to be 1 type, and it does not interfere even if it is a mixture of 2 or more types.

  Among the above organic binders, synthetic rubbers such as acrylic rubber and nitrile rubber; water-soluble polymer compounds such as carboxymethyl cellulose and polyvinyl alcohol; or acrylic resins are preferable, among which acrylic rubber, nitrile rubber, carboxymethyl cellulose, polyvinyl alcohol, acrylic An acrylic resin not contained in the rubber is particularly preferable. These binders are easy to prepare or obtain an organic binder liquid, and are easily impregnated into the mat, exhibiting sufficient thickness restraining force even with a relatively low content, and the resulting molded product is It is soft and excellent in strength, and can be suitably used because it is easily decomposed or burnt off under the operating temperature conditions.

  When the mat of the present invention contains an organic binder, the content is particularly preferably less than 10% by weight, particularly preferably 2.5% by weight or less.

  The exhaust gas cleaning apparatus of the present invention is an exhaust gas cleaning apparatus comprising a catalyst carrier, a casing that covers the outside of the catalyst carrier, and a mat interposed between the catalyst carrier and the casing, As this mat, the mat of the present invention is used, and since the mat peel strength is high, the mat is easy to handle and work when assembling the exhaust gas cleaning device, and the holding performance of the catalyst carrier after assembly is also good. Therefore, the exhaust gas cleaning efficiency is also excellent.

  The configuration of the exhaust gas cleaning device is not particularly limited, and the present invention can be applied to a general exhaust gas cleaning device including a catalyst carrier, a casing, and a mat as a gripping body for the catalyst carrier. It is.

DESCRIPTION OF SYMBOLS 1 Mat-like aggregate 2 Needle mark 10,20 Board 30 Needle 31 Head 32 Needle body 33 Spiral groove 42 Guide 43 Coil spring 51 Needle board 52 Support plate 52a Opening (needle insertion hole)

Claims (6)

Consists of a mat-like aggregate of inorganic fibers,
In an inorganic fiber molded body having needle marks extending in a direction including the thickness direction of the mat-like aggregate,
An inorganic fiber molded article, wherein at least some of the fibers are spirally entangled in the needle marks.   2. The method for producing an inorganic fiber molded body according to claim 1, further comprising a needling step of inserting the needle into the mat-like assembly while rotating the needle around its axis.   An apparatus for manufacturing an inorganic fiber molded body having a needle for piercing a mat-like assembly, wherein the needle rotates at the time of piercing. In Claim 3, the needle is rotatable about its axis, and is an apparatus for producing an inorganic fiber molded body in which a spiral groove is provided in the needle,
A needle board that holds the needle so as to be rotatable about its axis and is capable of reciprocating in the axial direction of the needle;
A support plate having a needle insertion hole through which the needle is inserted;
An apparatus for producing an inorganic fiber molded body, comprising: a guide protruding from an inner surface of the needle insertion hole and engaged with a spiral groove of the needle.   A mat for an exhaust gas cleaning apparatus, comprising the inorganic fiber molded body according to claim 1.   The exhaust gas cleaning apparatus comprising: a catalyst carrier; a casing that covers the outside of the catalyst carrier; and a mat interposed between the catalyst carrier and the casing. An exhaust gas cleaning apparatus characterized by

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