JP7555781B2 - Inorganic fiber assembly with inorganic sheet material, method for producing inorganic fiber assembly with inorganic sheet material, and exhaust gas purification device - Google Patents

Description

The present invention relates to an inorganic fiber aggregate with an inorganic sheet material, a manufacturing method for an inorganic fiber aggregate with an inorganic sheet material, and an exhaust gas purification device.

Exhaust gas emitted from internal combustion engines such as diesel engines contains particulate matter (PM) such as soot, and in recent years, the harm that this PM poses to the environment and human body has become a problem. In addition, exhaust gas also contains harmful gas components such as CO, HC, and NOx, and there are concerns about the impact that these harmful gas components have on the environment and human body.

In response to this, various exhaust gas purification devices have been proposed that capture PM in exhaust gas and purify harmful gas components. The exhaust gas purification devices are composed of an exhaust gas treatment body made of porous ceramic, a casing that houses the exhaust gas treatment body, and a holding seal material made of an inorganic fiber aggregate that is arranged between the exhaust gas treatment body and the casing. The main purpose of this holding seal material is to prevent the exhaust gas treatment body from coming into contact with the casing that covers its outer periphery and being damaged due to vibrations and impacts caused by the running of the automobile, etc., and to prevent exhaust gas from leaking from between the exhaust gas treatment body and the casing. For this reason, the holding seal material is required to have the function of increasing the surface pressure generated by the repulsive force caused by compression, and to securely hold the exhaust gas treatment body.

As such a retaining seal material, Patent Document 1 discloses a retaining seal material in which the surface of inorganic fibers is covered with a binder layer, and the binder layer contains an organic binder, inorganic particles, and a polymeric dispersant.
Patent Document 2 discloses a mounting mat for an exhaust gas treatment device having two opposite main surfaces and at least one edge surface extending between the main surfaces, wherein at least a portion of the at least one edge surface includes a protective coating containing inorganic particles, the inorganic particles having an average diameter of at least 1 μm.

Furthermore, the inorganic fiber aggregate constituting such a holding and sealing material may also be used as a gasket.
For example, Patent Document 3 discloses a beater sheet-like gasket containing at least inorganic fibers, an elastic material, and a binder, the gasket being characterized in that it is made of a compound containing 10 to 30% by weight of ceramic inorganic fibers, 2 to 5% by weight of an organic elastic material, and 2 to 5% by weight of an inorganic binder, as well as 5 to 30% by weight of natural mica and 60 to 80% by weight of unexpanded vermiculite.

International Publication No. WO 2014/168089 Special table 2018-505984 publication Japanese Patent Publication No. 4-288388

Most of the exhaust gas that flows into the exhaust gas purification device passes through the exhaust gas treatment body and is purified. However, some of the exhaust gas may not pass through the exhaust gas treatment body and may collide with the holding seal material that holds the exhaust gas treatment body.
In the holding seal material (mounting mat) described in Patent Documents 1 and 2, there are many voids on the surface where the exhaust gas collides. Therefore, the exhaust gas that collides with the holding seal material (mounting mat) may pass through the voids and pass through the exhaust gas purification device. If the exhaust gas passes through the exhaust gas purification device without passing through the exhaust gas treatment body, the problem occurs that the exhaust gas cannot be purified. Therefore, it is desired to improve the sealing property of the holding seal material.

In addition, the gasket made of inorganic fibers described in Patent Document 3 has insufficient shape conformability. Therefore, when the gasket described in Patent Document 3 is placed in the gasket space of a pipe and the gasket space of the pipe expands due to heat, gaps are likely to occur between the gasket and the wall surface of the gasket space.

The present invention has been made to solve the above problems, and the object of the present invention is to provide an inorganic fiber aggregate with an inorganic sheet material that has high sealing properties.

In other words, the inorganic fiber aggregate with inorganic sheet material of the present invention is characterized in that it comprises a sheet-like, single-layer inorganic fiber aggregate and an inorganic sheet material having a higher air resistance than the inorganic fiber aggregate, and that the inorganic sheet material is disposed on at least a portion of the surface of the inorganic fiber aggregate.

The inorganic fiber assembly with inorganic sheet material of the present invention has an inorganic sheet material having a higher airflow resistance than the inorganic fiber assembly, so that gas and other gases are less likely to pass through the inorganic sheet material portion.
Therefore, when the inorganic fiber assembly with inorganic sheet material of the present invention is arranged in an exhaust gas purification device or the like so that gas such as gas collides with the inorganic sheet material, the sealing performance is improved.

In this specification, the "surface of the inorganic fiber aggregate" refers to the part of the inorganic fiber aggregate that faces the outside, and in the case where through holes are formed in the inorganic fiber aggregate, this concept includes the inner walls of the through holes.

In the inorganic fiber aggregate with inorganic sheet material of the present invention, the inorganic sheet material may be made of at least one metal selected from the group consisting of stainless steel, aluminum, gold, silver, copper, iron, tin, titanium alloys, and nickel alloys.
These materials are strong and highly heat resistant, so they are unlikely to break even if they are hit by gas or the like, and can maintain their sealing properties.

In the inorganic fiber assembly with an inorganic sheet material of the present invention, the inorganic sheet material may be made of at least one inorganic material selected from the group consisting of alumina, silica, glass and biosoluble materials.
When the inorganic sheet material is made of these materials, the fiber assembly with the inorganic sheet material has high strength and heat resistance.

In the inorganic fiber aggregate with inorganic sheet material of the present invention, the inorganic sheet material may be at least one selected from the group consisting of a foil, a plate, a woven fabric, a knitted fabric, and a nonwoven fabric.

In the inorganic fiber assembly with an inorganic sheet material of the present invention, the inorganic sheet material may be made of a material having air permeability.
Since the inorganic sheet material has a higher air flow resistance than the inorganic fiber assembly, even if the inorganic sheet material has air permeability, the sealing property of the inorganic fiber assembly with the inorganic sheet material is high.
In the inorganic fiber assembly with an inorganic sheet material of the present invention, the inorganic sheet material does not need to have air permeability.

In the inorganic fiber aggregate with inorganic sheet material of the present invention, pressure is applied to the inorganic fiber aggregate with inorganic sheet material from above and below, and the inorganic fiber aggregate is compressed until the density of the inorganic fiber aggregate becomes 0.3 g/ ^cm3 , and it is preferable that the vertical thickness of the inorganic fiber aggregate with inorganic sheet material after relaxation for 20 minutes is 120% or more of the vertical thickness at the time of compression.
The inorganic fiber assembly with an inorganic sheet material having such characteristics has sufficient repulsive force and shape conformability. Therefore, for example, when the inorganic fiber assembly with an inorganic sheet material of the present invention is used for a gasket, it can sufficiently conform even if the gasket space of a pipe expands due to thermal expansion.

In the inorganic fiber aggregate with inorganic sheet material of the present invention, it is preferable that the inorganic fiber aggregate has a rectangular shape in a planar view having a longitudinal direction and a transverse direction, and has a first main surface, a second main surface opposite the first main surface, a first side surface formed along the longitudinal direction, and a second side surface opposite the first side surface.
When the inorganic fiber aggregate has a rectangular shape in a plan view, the inorganic fiber aggregate with inorganic sheet material can be easily wrapped around a columnar exhaust gas treatment body.

In the inorganic fiber aggregate with inorganic sheet material of the present invention, it is preferable that the inorganic sheet material is disposed on at least a part of any of the first main surface, the second main surface, the first side surface, and the second side surface.
In the case where an inorganic sheet material is disposed on a portion of either the first main surface or the second main surface, when an exhaust gas purification device is produced by pressing in an exhaust gas treatment body wrapped with an inorganic fiber aggregate with inorganic sheet material, the inorganic sheet material is pressed toward the inorganic fiber aggregate, so that a portion of the inorganic sheet material is embedded inside the inorganic fiber aggregate. Therefore, when exhaust gas flows into the exhaust gas purification device and passes through the inorganic fiber aggregate, the inorganic sheet material embedded in the inorganic fiber aggregate acts as a resistance. As a result, it becomes difficult for the exhaust gas to pass through the inorganic fiber aggregate.
Furthermore, when an inorganic sheet material is disposed on a portion of either the first side surface or the second side surface of the inorganic fiber aggregate, when an exhaust gas purification device is produced by pressing in an exhaust gas treatment body wrapped with the inorganic fiber aggregate with inorganic sheet material, the exhaust gas collides with the inorganic sheet material when it flows in, making it difficult for the exhaust gas to pass through the inorganic fiber aggregate with inorganic sheet material.

In the inorganic fiber aggregate with an inorganic sheet material of the present invention, the inorganic fiber aggregate may have through holes formed therein that penetrate the inorganic fiber aggregate in the thickness direction.
When through holes are formed in the inorganic fiber assembly, sensors, electrodes, etc. can be disposed therein and the through holes also serve as bypass flow paths.

In the inorganic fiber aggregate with an inorganic sheet material of the present invention, the inorganic sheet material may be disposed on the inner wall of the through hole.
Even when the inorganic sheet material is disposed on the inner wall of the through hole, the effect of improving the sealing property can be obtained.

The inorganic fiber aggregate with inorganic sheet material of the present invention is preferably used as the retaining seal material of an exhaust gas purification device comprising an exhaust gas treatment body, a metal casing that houses the exhaust gas treatment body, and a retaining seal material that is arranged between the exhaust gas treatment body and the metal casing.
As described above, the inorganic fiber aggregate with an inorganic sheet material of the present invention has high sealing properties. Therefore, when the inorganic fiber aggregate with an inorganic sheet material of the present invention is used as a holding seal material in an exhaust gas purification device, it is possible to prevent exhaust gas from passing through the holding seal material.

In the inorganic fiber aggregate with inorganic sheet material of the present invention, the inorganic fiber aggregate has a rectangular shape in a planar view having a longitudinal direction and a transverse direction, and has a first main surface, a second main surface opposite the first main surface, a first side surface formed along the longitudinal direction, and a second side surface opposite the first side surface, and at least the inorganic sheet material is arranged on a portion of any of the first main surface, the second main surface, the first side surface, and the second side surface, and it is preferable that in the gas flow rate test described below, the gas flow rate (L/min) on the exhaust gas inlet side when the inorganic fiber aggregate with inorganic sheet material is used and the gas pressure on the exhaust gas inlet side is 10 kPa is 80% or less of the gas flow rate (L/min) on the exhaust gas inlet side when the inorganic fiber aggregate without the inorganic sheet material is used and the gas pressure on the exhaust gas inlet side is 10 kPa.
Gas Flow Test:
An inorganic fiber assembly with an inorganic sheet material and an inorganic fiber assembly without an inorganic sheet material are prepared.
A non-breathable test cylinder is prepared, and an inorganic fiber aggregate with an inorganic sheet material and an inorganic fiber aggregate without an inorganic sheet material are each wound around the side of the test cylinder so that a first side of the inorganic fiber aggregate forms a circle, to produce a wound body.
Next, a cylindrical metal casing having an exhaust gas inlet and an exhaust gas outlet is prepared, and each wound body is pressed into the metal casing so that the inorganic sheet material is positioned closer to the exhaust gas inlet than the inorganic fiber aggregate and the packing density (GBD) of the inorganic fiber aggregate is 0.26 g/ ^cm3 .
Air is allowed to flow from the exhaust gas inlet of the metal casing, and the gas pressure (kPa) on the exhaust gas inlet side and the gas flow rate (L/min) on the exhaust gas inlet side are measured.

The fact that the inorganic fiber aggregate with inorganic sheet material of the present invention has the above parameters means that the inorganic fiber aggregate with inorganic sheet material of the present invention has high sealing properties when used as a retaining seal material for an exhaust gas purification device.

The inorganic fiber assembly with an inorganic sheet material of the present invention is preferably used as a gasket.
As described above, the inorganic fiber aggregate with an inorganic sheet material of the present invention has high sealing properties, and therefore, when the inorganic fiber aggregate with an inorganic sheet material of the present invention is used as a gasket, leakage of gas or the like can be prevented.

The method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention is a method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, and includes an inorganic fiber aggregate preparation step in which inorganic fibers are aggregated and then needle punched to prepare a sheet-like, single-layer inorganic fiber aggregate, and an inorganic sheet material arrangement step in which an inorganic sheet material is arranged on at least a portion of the surface of the inorganic fiber aggregate, and the inorganic fiber aggregate with the inorganic sheet material is characterized in that the inorganic sheet material has a higher air resistance than the inorganic fiber aggregate.

The needle mat obtained by needle punching can be used to manufacture the inorganic fiber aggregate with inorganic sheet material of the present invention.

In the manufacturing method of the inorganic fiber aggregate with inorganic sheet material of the present invention, it is preferable that the method further includes a binder applying step of applying a binder to the inorganic fiber aggregate, and a drying step of drying the inorganic fiber aggregate to which the binder has been applied.
By carrying out the binder impregnation step and the drying step, the binder can be adhered to the inorganic fiber aggregate.
The binder includes an organic binder and an inorganic binder.
The organic binder can prevent fibers from falling off and scattering from the inorganic fiber assembly.
The inorganic binder adheres to the surface of the inorganic fibers, thereby improving the surface pressure of the inorganic fiber assembly, and therefore, when the manufactured inorganic fiber assembly with inorganic sheet material is used in an exhaust gas purification device, the exhaust gas treatment body can be favorably held.
When the needle mat is an inorganic fiber aggregate, the inorganic fiber aggregate may or may not contain an organic binder and an inorganic binder.

In the method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, the drying step may be carried out after the binder attachment step, and then the inorganic sheet material arrangement step may be carried out.
In the method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, the binder attachment step may be followed by the inorganic sheet material arrangement step, and then the drying step may be carried out.
In the method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, the binder attaching step may be carried out after the inorganic sheet material arranging step, and then the drying step may be carried out.
In the method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, the binder attachment step and the inorganic sheet material arrangement step may be carried out simultaneously, and then the drying step may be carried out.
That is, in the method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, the order of the binder attachment step and the inorganic sheet material arrangement step is not particularly limited.

The method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention is a method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, and includes an inorganic fiber-binder mixed liquid preparation step of mixing inorganic fibers and a binder to form an inorganic fiber-binder mixed liquid, and a papermaking step of forming an inorganic fiber aggregate by papermaking and dehydrating the inorganic fiber-binder mixed liquid, and is characterized in that after the papermaking step, the method includes an inorganic sheet material placement step of placing an inorganic sheet material on the inorganic fiber aggregate, or in that in the papermaking step, the inorganic fiber aggregate is papermade on an inorganic sheet material.

The inorganic fiber aggregate with inorganic sheet material of the present invention can be manufactured by using the paper mat obtained by papermaking.

In the method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, after the papermaking step, a drying step of drying the inorganic fiber aggregate may be carried out, and after the drying step, the inorganic sheet material arrangement step may be carried out.
In addition, in the manufacturing method of the inorganic fiber aggregate with inorganic sheet material of the present invention, the inorganic sheet material arrangement step may be carried out after the papermaking step, and a drying step of drying the inorganic fiber aggregate may be carried out after the inorganic sheet material arrangement step.
That is, in the method for producing an inorganic fiber aggregate with an inorganic sheet material of the present invention, the order of the drying step and the inorganic sheet material arrangement step is not particularly limited.

In the manufacturing method of the inorganic fiber aggregate with inorganic sheet material of the present invention, during the papermaking process, the inorganic fiber-binder mixed liquid is placed on the inorganic sheet material, and then the inorganic fiber-binder mixed liquid is paper-made and dehydrated to produce the inorganic fiber aggregate, and after the papermaking process, a drying process is performed to dry the inorganic fiber aggregate.
When an inorganic fiber aggregate with an inorganic sheet material is manufactured in this manner, the process of producing the inorganic fiber aggregate and the process of arranging the inorganic sheet material can be carried out simultaneously, thereby improving work efficiency.

FIG. 1 is a perspective view that illustrates an example of an inorganic fiber aggregate with an inorganic sheet material according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view that illustrates an example of an exhaust gas purifying device that uses the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention. FIG. 3A is a perspective view that illustrates a process for producing a wound body in a gas flow test. FIG. 3B is a side view that typically illustrates how the wound body is pressed into the metal casing in the gas flow rate test. FIG. 3C is a cross-sectional view that typically shows how the gas flow rate and gas pressure are measured in a gas flow rate test. FIG. 4A is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on a side surface of an inorganic fiber assembly. FIG. 4B is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on the side surface of an inorganic fiber assembly having through holes. FIG. 4C is a perspective view that typically shows an example of an inorganic fiber aggregate with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on a main surface of the inorganic fiber aggregate. FIG. 4D is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on the main surface of an inorganic fiber assembly having through holes. FIG. 4E is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic fiber assembly has through holes and an inorganic sheet material is disposed on the inner walls of the through holes. FIG. 4F is a perspective view that shows a schematic example of an inorganic fiber aggregate with an inorganic sheet material of the present invention, in which an inorganic sheet material is disposed on the inner walls of the through holes of an inorganic fiber aggregate having through holes and on the main surface of the inorganic fiber aggregate. FIG. 5A is a perspective view that typically illustrates one example of an exhaust gas treatment body that constitutes the exhaust gas purification device of the present invention. FIG. 5B is a cross-sectional view taken along line AA of FIG. 5A. FIG. 6 is a graph plotting the results of the gas flow rate test, with y being the gas flow rate (L/min) on the exhaust gas inlet side and x being the gas pressure (kPa) on the exhaust gas inlet side. FIG. 7 is a perspective view that illustrates an example of an inorganic fiber aggregate with an inorganic sheet material according to the second embodiment of the present invention. FIG. 8 is a cross-sectional view that illustrates an example of a pipe in which an inorganic fiber aggregate with an inorganic sheet material according to the second embodiment of the present invention is used.

Detailed Description of the Invention
The inorganic fiber aggregate with inorganic sheet material of the present invention will be specifically described below. However, the present invention is not limited to the following configuration, and can be appropriately modified and applied within the scope of the present invention. Note that the present invention also includes a combination of two or more of the individual preferred configurations of the present invention described below.

The inorganic fiber aggregate with inorganic sheet material of the present invention is characterized in that it comprises a sheet-like, single-layer inorganic fiber aggregate and an inorganic sheet material having a higher air resistance than the inorganic fiber aggregate, and that the inorganic sheet material is disposed on at least a portion of the surface of the inorganic fiber aggregate.

The inorganic fiber assembly with inorganic sheet material of the present invention has an inorganic sheet material having a higher airflow resistance than the inorganic fiber assembly, so that gas and other gases are less likely to pass through the inorganic sheet material portion.
Therefore, when the inorganic fiber assembly with inorganic sheet material of the present invention is arranged in an exhaust gas purification device or the like so that gas such as gas collides with the inorganic sheet material, the sealing performance is improved.

As long as the inorganic fiber aggregate with inorganic sheet material of the present invention has the above configuration, it may have any other configuration within the scope of the above-mentioned effects of the present invention.

Each embodiment of the inorganic fiber aggregate with inorganic sheet material of the present invention will be described below with reference to the drawings.

First Embodiment
The inorganic fiber aggregate with an inorganic sheet material according to the first embodiment of the present invention is an inorganic fiber aggregate with an inorganic sheet material used as a holding sealer for an exhaust gas purification device.
The exhaust gas purification device including the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention is also one aspect of the present invention.

FIG. 1 is a perspective view that illustrates an example of an inorganic fiber aggregate with an inorganic sheet material according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view that illustrates an example of an exhaust gas purifying device that uses the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention.

The inorganic fiber aggregate 10 with inorganic sheet material shown in Figure 1 consists of a sheet-like, single-layer inorganic fiber aggregate 20 and an inorganic sheet material 30 that has a higher air resistance than the inorganic fiber aggregate 20.

In this specification, "sheet-like and single layer" does not mean an inorganic fiber aggregate formed by stacking two or more sheets, but means an inorganic fiber aggregate having a front surface, a back surface opposite the front surface, and a side surface connecting the front surface and the back surface.

The inorganic fiber aggregate 20 shown in Figure 1 has a rectangular shape in a planar view having a longitudinal direction L and a transverse direction S, and has a first main surface 21, a second main surface 22 opposite the first main surface 21, a first side surface 23 formed along the longitudinal direction L, a second side surface 24 opposite the first side surface 23, a first end portion 25 formed along the transverse direction S, and a second end portion 26 opposite the first end portion 25.
The first end 25 and the second end 26 are formed with a protrusion 25a and a recess 26a, respectively.
The convex portion 25a and the concave portion 26a are shaped to fit together when the inorganic fiber assembly 10 with inorganic sheet material is rolled up so that the first end portion 25 and the second end portion 26 are in contact with each other.
The inorganic sheet material 30 is disposed so as to cover the entire first side surface 23 .

In the inorganic fiber aggregate with inorganic sheet material of the present invention, the inorganic sheet material may be arranged so as to cover only a portion of the first side surface 23 in the longitudinal direction, or may be arranged so as to cover only a portion of the first side surface 23 in the thickness direction.

In addition, in the inorganic fiber aggregate with inorganic sheet material of the present invention, it is preferable that the first end and the second end are formed so that when the inorganic fiber aggregate with inorganic sheet material is rolled up so that the first end and the second end are in contact, the first side is positioned on the same plane and the second side is positioned on the same plane.
For example, the first end and the second end may have no convex or concave portion and may have a straight line shape. The first end and the second end may be parallel to each other and may have a straight line shape oblique to the short side direction. The first end and the second end may have corresponding notches and protrusions. Examples of the notches and protrusions include L-shaped notches and protrusions and semicircular notches and protrusions.

2, the exhaust gas purification device 1 includes an exhaust gas treatment body 40, a metal casing 50 that houses the exhaust gas treatment body 40, and an inorganic fiber aggregate 10 with an inorganic sheet material disposed between the exhaust gas treatment body 40 and the metal casing 50. In other words, the inorganic fiber aggregate 10 with an inorganic sheet material functions as a holding sealer.
In addition, the metal casing 50 has an exhaust gas inlet 51 and an exhaust gas exhaust outlet 52, and is arranged so that the first side 23 of the inorganic fiber aggregate 20 is located on the exhaust gas inlet 51 side and the second side 24 of the inorganic fiber aggregate 20 is located on the exhaust gas exhaust outlet side.
In addition, in an exhaust gas purification device using the inorganic fiber aggregate with inorganic sheet material of the present invention, the first side of the inorganic fiber aggregate may be positioned on the exhaust gas exhaust outlet side, and the second side of the inorganic fiber aggregate may be positioned on the exhaust gas inlet side.

In the exhaust gas purification device 1, exhaust gas G flows in through the exhaust gas inlet 51. At this time, most of the exhaust gas G is purified by passing through the exhaust gas treatment body 40.

At this time, some of the exhaust gas G collides with the holding seal material. If the holding seal material is a conventional inorganic fiber aggregate and no inorganic sheet material is provided, the exhaust gas G may pass through the inside of the inorganic fiber aggregate and escape from the exhaust gas outlet 52.

On the other hand, in the exhaust gas purification device 1 , when the exhaust gas G collides with the inorganic fiber assembly 10 with the inorganic sheet material, which is the holding sealing material, it first collides with the inorganic sheet material 30 .
Since the inorganic sheet material 30 has a high airflow resistance, the exhaust gas G is less likely to penetrate the inorganic sheet material 30 and is less likely to reach the inorganic fiber aggregate 20 .
Therefore, the exhaust gas G can be prevented from passing through the inside of the inorganic fiber aggregate 20 and escaping through the exhaust gas exhaust port 52 .

Next, we will explain the preferred aspects of each configuration of the exhaust gas purification device 1 including the inorganic fiber aggregate 10 with inorganic sheet material.

(Inorganic fiber assembly)
The inorganic fiber aggregate 20 is not limited, but may be a needle mat obtained by needle punching, a mat obtained by a wet papermaking method, or the like.

The inorganic fibers constituting the inorganic fiber assembly 20 preferably have an average fiber diameter of 3 to 50 μm, and more preferably have an average fiber length of 100 to 100,000 μm.
The inorganic fibers constituting the inorganic fiber aggregate 20 preferably include at least one type selected from alumina fibers, silica fibers, alumina-silica fibers, mullite fibers, glass fibers, and biosoluble fibers.
When the inorganic fibers constituting the inorganic fiber aggregate 20 have the above-mentioned shape and material, the surface pressure of the inorganic fiber aggregate 20 can be sufficiently improved, and in an exhaust gas purification device in which the inorganic fiber aggregate 20 is used, the exhaust gas treatment body is less likely to fall off.

The thickness of the inorganic fiber assembly 20 is preferably 2.0 to 30 mm.
If the thickness of the inorganic fiber aggregate exceeds 30 mm, the inorganic fiber aggregate loses flexibility, making it difficult to handle when winding the inorganic fiber aggregate around the exhaust gas treatment body, and the inorganic fiber aggregate is prone to wrinkles and cracks during winding.
If the thickness of the inorganic fiber aggregate is less than 2.0 mm, the surface pressure of the inorganic fiber aggregate is not sufficient to hold the exhaust gas treatment body. Therefore, the exhaust gas treatment body is likely to fall off. In addition, if a volume change occurs in the exhaust gas treatment body, the inorganic fiber aggregate is unlikely to absorb the volume change of the exhaust gas treatment body. Therefore, cracks and the like are likely to occur in the exhaust gas treatment body.

The inorganic fiber aggregate 20 has a basis weight (weight per unit area) of preferably 200 to 4000 g/m ² , and more preferably 1000 to 3500 g/m ² .
If the basis weight of the inorganic fiber aggregate is less than 200 g/ ^m2 , the retention force is insufficient, and if the basis weight of the inorganic fiber aggregate is more than 4000 g/ ^m2 , the bulk of the inorganic fiber aggregate is difficult to reduce. Therefore, when an exhaust gas purification device is manufactured using such an inorganic fiber aggregate, the exhaust gas treatment body is likely to fall off.

The bulk density of the inorganic fiber aggregate 20 (bulk density of the inorganic fiber aggregate before winding) is preferably 0.10 to 0.30 g/cm ³ , and more preferably 0.10 to 0.25 g/cm ³ .
If the bulk density of the inorganic fiber aggregate is less than 0.10 g/cm ³ , the inorganic fibers are weakly entangled and tend to peel off, making it difficult to maintain the inorganic fiber aggregate in a predetermined shape.
Furthermore, if the bulk density of the inorganic fiber aggregate exceeds 0.30 g/cm ³ , the inorganic fiber aggregate becomes hard, so that the winding property around the exhaust gas treatment body decreases and the inorganic fiber aggregate becomes easily cracked.

The inorganic fiber aggregate 20 may contain an organic binder or an inorganic binder.
Examples of the organic binder include rubber-based resins, styrene-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, and polyurethane resins.
Examples of the inorganic binder include alumina sol, silica sol, aerogel, fumed silica, and titanium particles.
The organic binder can prevent fibers from falling off and scattering from the inorganic fiber assembly.
The inorganic binder adheres to the surface of the inorganic fibers, thereby improving the surface pressure of the inorganic fiber assembly, thereby enabling the exhaust gas treatment body to be favorably held.
When the needle mat is an inorganic fiber aggregate, the inorganic fiber aggregate may or may not contain an organic binder and an inorganic binder.

The inorganic fiber aggregate may have through holes formed therethrough in the thickness direction.
When the inorganic fiber assembly has through holes formed therein, sensors, electrodes, etc. can be disposed therein and the through holes also serve as bypass flow paths.

(Inorganic sheet material)
The material constituting the inorganic sheet material may be made of a material that does not have air permeability, as long as the air permeability resistance of the inorganic sheet material is high compared to that of the inorganic fiber aggregate.
Since the inorganic sheet material has a higher airflow resistance than the inorganic fiber assembly, even if the inorganic sheet material has air permeability, the sealing property of the inorganic fiber assembly with the inorganic sheet material is high.

The material constituting the inorganic sheet material may be made of at least one metal selected from the group consisting of stainless steel, aluminum, gold, silver, copper, iron, tin, titanium alloys, and nickel alloys. It may also be made of at least one inorganic material selected from the group consisting of alumina, silica, glass, and biosoluble materials.

When the inorganic sheet material is made of a metal, it has strength and high heat resistance, so that it is difficult to break even when hit by a gas or the like, and the sealing performance can be maintained.
When the inorganic sheet material is made of a metal, the inorganic sheet material is not particularly limited as long as it is a sheet-like material formed from a metal, and examples thereof include metal foil in the form of a foil, a metal plate in the form of a plate, a woven fabric obtained by weaving metal fibers, a knitted fabric obtained by knitting metal fibers, and a nonwoven fabric made of assembled metal fibers.

When the inorganic sheet material is a foil made of metal, the thickness of the foil is preferably 1 to 300 μm.
If the thickness of the foil is less than 1 μm, the foil becomes easily torn.
If the thickness of the foil exceeds 300 μm, it becomes difficult to bend and difficult to handle.

More preferably, the foil is made of copper.
Copper has high flexibility, so when an inorganic fiber assembly with an inorganic sheet material in which copper is used is bent, the inorganic sheet material is less likely to break or be damaged.

When the inorganic sheet material is made of at least one inorganic material selected from the group consisting of alumina, silica, glass and biosoluble materials, the fiber assembly with the inorganic sheet material has high strength and heat resistance.
In this case, the shape of the inorganic sheet material is not particularly limited as long as it is in the form of a sheet, and examples thereof include a foil, a plate, a woven fabric, a knitted fabric, and a nonwoven fabric.
The inorganic sheet material is preferably made of ceramic, and is preferably a plate-shaped ceramic plate, a woven fabric obtained by weaving ceramic fibers, a knitted fabric obtained by knitting ceramic fibers, or a nonwoven fabric made of assembled ceramic fibers.

When the inorganic sheet material is made of ceramic fibers, it is preferable that the fiber diameter of the ceramic fibers is 3 to 50 μm.

The material constituting the inorganic sheet material may be made of a material having air permeability.
Since the inorganic sheet material has a higher airflow resistance than the inorganic fiber assembly, even if the inorganic sheet material has air permeability, the sealing property of the inorganic fiber assembly with the inorganic sheet material is high.
In the inorganic fiber assembly with an inorganic sheet material of the present invention, the inorganic sheet material does not need to have air permeability.

(Inorganic fiber assembly with inorganic sheet material)
In the inorganic fiber aggregate 10 with an inorganic sheet material, the inorganic sheet material 30 is preferably adhered to the inorganic fiber aggregate with an adhesive.
The adhesive is not particularly limited, and may be an inorganic adhesive or an organic adhesive.

In the inorganic fiber aggregate 10 with inorganic sheet material, the inorganic sheet material 30 is arranged so as to cover the entire first side surface 23 of the inorganic fiber aggregate 20, but in the inorganic fiber aggregate with inorganic sheet material of the present invention, the inorganic sheet material may be arranged so as to cover only a portion of the first side surface 23 of the inorganic fiber aggregate 20, or may be arranged so as to cover a portion or the entire second side surface 24 of the inorganic fiber aggregate. Moreover, the inorganic sheet material may be arranged so as to cover the entire surface of the inorganic fiber aggregate 20.
In either embodiment, the inorganic sheet material is disposed, so that the exhaust gas G can be prevented from passing through the inorganic fiber assembly 20 and escaping from the exhaust gas exhaust port 52 in the exhaust gas purification device.

If an inorganic sheet material is disposed on the entire surface of the inorganic fiber aggregate 20, it becomes difficult to wrap the inorganic fiber aggregate 10 with the inorganic sheet material around the exhaust gas treatment body 40. For this reason, it is preferable that the inorganic sheet material is disposed so that a portion of the first main surface 21 and the second main surface 22 of the inorganic fiber aggregate 20 is exposed.
Furthermore, in the direction from the first side surface 23 to the second side surface 24 of the inorganic fiber aggregate 20, it is more preferable that 5 to 95% of the area of the first main surface 21 of the inorganic fiber aggregate 20 is exposed, and it is even more preferable that in the direction from the first side surface 23 to the second side surface 24 of the inorganic fiber aggregate 20, 5 to 95% of the area of the second main surface 22 of the inorganic fiber aggregate 20 is exposed.

In the inorganic fiber aggregate with an inorganic sheet material of the present invention, when through holes are formed in the inorganic fiber aggregate, an inorganic sheet material may be disposed on the inner wall of the through hole. In this case, the inorganic sheet material may be disposed on the entire inner wall of the through hole, or may be disposed on only a part of the inner wall of the through hole.
Even when the inorganic sheet material is disposed on the inner wall of the through hole, the effect of improving the sealing property can be obtained.
In addition to the inner walls of the through holes, the inorganic sheet material may be arranged on a portion of the first main surface and/or the second main surface of the inorganic fiber aggregate, or on a portion of the first side surface and/or the second side surface of the inorganic fiber aggregate.

The inorganic fiber aggregate 10 with inorganic sheet material is compressed by applying pressure from above and below the inorganic fiber aggregate 10 with inorganic sheet material until the inorganic fiber aggregate 20 has a density of 0.3 g/ ^cm3 , and after relaxing for 20 minutes, the vertical thickness of the inorganic fiber aggregate 10 with inorganic sheet material is preferably 120% or more, and more preferably 150% or more, of the vertical thickness at the time of compression.
The inorganic fiber assembly 10 with inorganic sheet material having such characteristics has sufficient repulsive force and shape conformability, and can therefore firmly hold the exhaust gas treatment body.

In the inorganic fiber aggregate 10 with inorganic sheet material, the inorganic fiber aggregate 20 has a rectangular shape in plan view with a longitudinal direction L and a lateral direction S, and has a first main surface 21, a second main surface 22 opposite the first main surface 21, a first side surface 23 formed along the longitudinal direction, and a second side surface 24 opposite the first side surface 23. In the gas flow rate test described below, the inorganic fiber aggregate 10 with inorganic sheet material is preferably such that the gas flow rate (L/min) on the exhaust gas inlet side when the inorganic fiber aggregate 10 with inorganic sheet material is used and the gas pressure on the exhaust gas inlet side is 10 kPa is 80% or less of the gas flow rate (L/min) on the exhaust gas inlet side when the inorganic fiber aggregate 20 without the inorganic sheet material 30 is used and the gas pressure on the exhaust gas inlet side is 10 kPa.

<Gas flow rate test>
FIG. 3A is a perspective view that illustrates a process for producing a wound body in a gas flow test.
FIG. 3B is a side view that typically illustrates how the wound body is pressed into the metal casing in the gas flow rate test.
FIG. 3C is a cross-sectional view that typically shows how the gas flow rate and gas pressure are measured in a gas flow rate test.
In the gas flow test, as shown in FIG. 3A , first, a non-breathable test cylinder 45 is prepared, and then the inorganic fiber aggregate 10 with inorganic sheet material is wrapped around the side of the test cylinder 45 so that the first side 23 of the inorganic fiber aggregate 20 forms a circle, to produce a wrapped body 46.
In the inorganic fiber assembly 10 with an inorganic sheet material shown in FIG. 3A, the inorganic sheet material 30 is disposed on the first side surface 23.

Next, as shown in FIG. 3B , a cylindrical metal casing 50 having an exhaust gas inlet 51 and an exhaust gas outlet 52 is prepared, and the inorganic sheet material 30 is positioned closer to the exhaust gas inlet 51 than the inorganic fiber aggregate 20, and the wound body 46 is pressed into the metal casing 50 so that the packing density (GBD) of the inorganic fiber aggregate 20 is 0.26 g/ ^cm3 .

Next, as shown in FIG. 3C, gas G is allowed to flow through the exhaust gas inlet 51 of the metal casing 50, and the gas flow rate on the exhaust gas inlet 51 side and the gas pressure on the exhaust gas inlet 51 side are measured.

In addition, instead of using the inorganic fiber aggregate 10 with inorganic sheet material, a wound body is made using an inorganic fiber aggregate 20 without an inorganic sheet material 30 arranged thereon, and the gas flow rate on the exhaust gas inlet 51 side and the gas pressure on the exhaust gas inlet 51 side are measured in a similar manner.

The fact that the inorganic fiber aggregate 10 with inorganic sheet material has the above parameters means that the inorganic fiber aggregate 10 with inorganic sheet material has high sealing properties when used as a retaining sealing material for the exhaust gas purification device 1.

Furthermore, in the above gas flow rate test, when an inorganic fiber aggregate 10 with an inorganic sheet material is used, it is preferable that the following formula (1) is satisfied when the gas flow rate (L/min) on the exhaust gas inlet side is y and the gas pressure (kPa) on the exhaust gas inlet side is x.
y<5.0x...(1)

In the inorganic fiber aggregate 10 with inorganic sheet material, the inorganic sheet material 30 is arranged on the first side 23 of the inorganic fiber aggregate 20, but in the inorganic fiber aggregate with inorganic sheet material of the present invention, the inorganic sheet material may be arranged on the second side of the inorganic fiber aggregate.

In the inorganic fiber aggregate with an inorganic sheet material of the present invention, the inorganic sheet material may be disposed on a part of the first main surface and the second main surface of the inorganic fiber aggregate.
In this case, when an exhaust gas purification device is manufactured by pressing in an exhaust gas treatment body wrapped with an inorganic fiber aggregate with an inorganic sheet material, the inorganic sheet material is pressed against the inorganic fiber aggregate, so that a part of the inorganic sheet material is embedded inside the inorganic fiber aggregate. Therefore, when exhaust gas flows into the exhaust gas purification device and passes through the inorganic fiber aggregate, the inorganic sheet material embedded in the inorganic fiber aggregate acts as a resistance. As a result, it becomes difficult for the exhaust gas to pass through the inorganic fiber aggregate.

The arrangement of the inorganic sheet material in the inorganic fiber assembly with an inorganic sheet material of the present invention will be exemplified below with reference to the drawings.
FIG. 4A is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on a side surface of an inorganic fiber assembly.
As shown in FIG. 4A , in the inorganic fiber assembly 10 with an inorganic sheet material of the present invention, an inorganic sheet material 30 may be disposed on a portion of the first side surface 23 and the second side surface 24 .

FIG. 4B is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on the side surface of an inorganic fiber assembly having through holes.
As shown in FIG. 4B , in the inorganic fiber aggregate 10 with inorganic sheet material of the present invention, the inorganic fiber aggregate 20 may have through holes 27, and an inorganic sheet material 30 may be disposed on a portion of the first side surface 23 and the second side surface 24.

FIG. 4C is a perspective view that typically shows an example of an inorganic fiber aggregate with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on a main surface of the inorganic fiber aggregate.
As shown in FIG. 4C , in the inorganic fiber assembly 10 with an inorganic sheet material of the present invention, an inorganic sheet material 30 may be disposed on a portion of the first main surface 21 .

FIG. 4D is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic sheet material is disposed on the main surface of an inorganic fiber assembly having through holes.
As shown in FIG. 4D , in the inorganic fiber aggregate 10 with an inorganic sheet material of the present invention, the inorganic fiber aggregate 20 may have through holes 27 , and an inorganic sheet material 30 may be disposed on a portion of the first main surface 21 .

FIG. 4E is a perspective view that typically shows an example of an inorganic fiber assembly with an inorganic sheet material of the present invention in which an inorganic fiber assembly has through holes and an inorganic sheet material is disposed on the inner walls of the through holes.
As shown in FIG. 4E , in the inorganic fiber aggregate 10 with inorganic sheet material of the present invention, the inorganic fiber aggregate 20 may have through holes 27 , and an inorganic sheet material 30 may be disposed on a part of an inner wall 28 of the through hole 27 .

FIG. 4F is a perspective view that shows a schematic example of an inorganic fiber aggregate with an inorganic sheet material of the present invention, in which an inorganic sheet material is disposed on the inner walls of the through holes of an inorganic fiber aggregate having through holes and on the main surface of the inorganic fiber aggregate.
As shown in Figure 4F, in the inorganic fiber aggregate 10 with inorganic sheet material of the present invention, the inorganic fiber aggregate 20 has a through hole 27, and an inorganic sheet material 30 is arranged on a portion of the inner wall 28 of the through hole 27, and the inorganic sheet material 30 may be arranged on a portion of the first main surface 21 and the second main surface 22.

(Exhaust gas treatment body)
Fig. 5A is a perspective view showing an example of an exhaust gas treating body constituting an exhaust gas purifying apparatus of the present invention, and Fig. 5B is a cross-sectional view taken along line AA of Fig. 5A.
As shown in FIGS. 5A and 5B, an exhaust gas treatment body 40 included in the exhaust gas purification device 1 has a cylindrical shape in which a large number of cells 41 are arranged in parallel in the longitudinal direction with cell walls 42 between them.
The exhaust gas treatment body 40 is an exhaust gas filter (honeycomb filter) in which one of the cells 41 is plugged with a plugging material 43 .

As shown in FIG. 5B, exhaust gas G discharged from an internal combustion engine and flowing into the exhaust gas treatment body 40 flows into one cell 41 that opens into the exhaust gas inlet end face of the exhaust gas treatment body 40, and passes through a cell wall 42 that separates the cells 41. At this time, PM in the exhaust gas is captured by the cell wall 42, and the exhaust gas is purified. The purified exhaust gas flows out of the other cell 41 that opens into the exhaust gas outlet end face, and is discharged to the outside.

The exhaust gas treatment body 40 shown in Figures 5A and 5B is a filter in which one end of the cell 41 is sealed with a sealing material 43, but the exhaust gas treatment body constituting the exhaust gas purification device of the present invention does not need to have the ends of the cells sealed. Such an exhaust gas treatment body can be suitably used as a catalyst carrier.

The exhaust gas treatment body 40 may be made of a non-oxide porous ceramic such as silicon carbide or silicon nitride, or may be made of an oxide porous ceramic such as sialon, alumina, cordierite, or mullite. Of these, silicon carbide is preferred.

When the exhaust gas treatment body 40 is made of porous ceramics of silicon carbide, the porosity of the porous ceramics is not particularly limited, but is preferably 35 to 60%.
If the porosity is less than 35%, the exhaust gas treatment body may easily become clogged, whereas if the porosity is more than 60%, the strength of the exhaust gas treatment body may decrease and the body may easily be broken.

The average pore size of the porous ceramic is preferably 5 to 30 μm.
If the average pore diameter is less than 5 μm, PM may easily cause clogging, whereas if the average pore diameter is more than 30 μm, PM may pass through the pores, making it impossible to capture the PM and preventing the filter from functioning as a filter.
The porosity and pore size can be measured by a conventionally known method using a scanning electron microscope (SEM) or the like.

The cell density in the cross section of the exhaust gas treatment body 40 is not particularly limited, but a preferred lower limit is 31.0 cells/ ^cm2 (200 cells/ ^inch2 ), a preferred upper limit is 93.0 cells/ ^cm2 (600 cells/ ^inch2 ), a more preferred lower limit is 38.8 cells/ ^cm2 (250 cells/ ^inch2 ), and a more preferred upper limit is 77.5 cells/ ^cm2 (500 cells/ ^inch2 ).

The exhaust gas treatment body 40 may support a catalyst for purifying the exhaust gas. The catalyst to be supported is preferably a precious metal such as platinum, palladium, or rhodium, and among these, platinum is more preferable. In addition, other catalysts such as alkali metals such as potassium or sodium, or alkaline earth metals such as barium may also be used. These catalysts may be used alone or in combination of two or more kinds.
When these catalysts are supported, PM can be easily burned and removed, and toxic exhaust gas can also be purified.

(Metal casing)
The metal casing 50 is generally cylindrical.
The inner diameter of the metal casing 50 (the inner diameter of the portion that houses the exhaust gas treatment body) is preferably slightly shorter than the diameter of the exhaust gas treatment body 40 around which the inorganic fiber assembly 10 with inorganic sheet material is wound.

The metal casing 50 is preferably made of stainless steel, although there is no particular limitation.

Next, we will explain the method for manufacturing the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention and the method for manufacturing an exhaust gas purification device using the inorganic fiber aggregate with inorganic sheet material.

In the manufacturing method of the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention, a method of manufacturing the inorganic fiber aggregate by needle punching or a method of manufacturing by papermaking can be used.

First, a method for producing an inorganic fiber aggregate by needle punching will be described.
A manufacturing method for an inorganic fiber aggregate with an inorganic sheet material by needle punching an inorganic fiber aggregate includes an inorganic fiber aggregate preparation step of aggregating inorganic fibers and then needle punching them to prepare a sheet-like, single-layer inorganic fiber aggregate, and an inorganic sheet material arrangement step of preparing an inorganic sheet material having a higher air resistance than the inorganic fiber aggregate and arranging the inorganic sheet material on at least a portion of the surface of the inorganic fiber aggregate.

(Inorganic fiber aggregate preparation process)
In this process, first, a spinning mixture made from a basic aluminum chloride aqueous solution, silica sol, etc. is spun by a blowing method to produce inorganic fibers. Next, the inorganic fibers are assembled and compressed to produce a continuous sheet-like product of a predetermined size, which is then needle-punched and then calcined to prepare a sheet-like, single-layer inorganic fiber assembly.

When the inorganic fiber aggregate is prepared by needle punching, the average length of the inorganic fibers is preferably 1 to 150 mm, and more preferably 10 to 80 mm.
If the average fiber length of the inorganic fibers is less than 1 mm, the fiber length of the inorganic fibers is too short, resulting in insufficient entanglement of the inorganic fibers with each other, making it difficult to obtain sufficient strength for the inorganic fiber aggregate, and the shape retention of the inorganic fiber aggregate is likely to decrease.
If the average fiber length of the fibers exceeds 150 mm, the fiber length is too long, and the number of fibers constituting the inorganic fiber aggregate decreases, resulting in a decrease in denseness.

The inorganic fiber aggregate may also be cut into a rectangular shape in plan view using a punching die or cutter.

(Inorganic sheet material placement process)
In the inorganic sheet material arrangement step, first, an inorganic sheet material is prepared.
A preferred structure for the inorganic sheet material has already been described, and therefore a detailed description thereof will be omitted here.
The inorganic sheet material can be cut into a desired shape using a cutter or the like.

Next, an inorganic sheet material is placed on at least a portion of the surface of the prepared inorganic fiber aggregate.
The method for arranging the inorganic sheet material is not particularly limited, and the inorganic sheet material may be attached with an adhesive, which may be an inorganic adhesive or an organic adhesive.

In the method for manufacturing an inorganic fiber aggregate with an inorganic sheet material according to the first embodiment of the present invention, the inorganic sheet material is made to have a higher airflow resistance than the inorganic fiber aggregate in the manufactured inorganic fiber aggregate with an inorganic sheet material.
Methods for making the airflow resistance of an inorganic sheet material higher than that of an inorganic fiber aggregate include adjusting the type and constituent materials of the inorganic sheet material, the type of inorganic fibers used in the inorganic fiber aggregate, the bulk density of the inorganic fiber aggregate, etc.

Through the above steps, the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention can be manufactured.

In addition, the above-mentioned method for manufacturing an inorganic fiber aggregate with an inorganic sheet material in which the inorganic fiber aggregate is produced by a needle punching method may further include a binder attachment process for attaching a binder to the inorganic fiber aggregate, and a drying process for drying the inorganic fiber aggregate to which the binder has been attached.
Each step will be described below.
In addition, when the inorganic fiber aggregate is produced by a needle punching method, the binder attachment step does not need to be performed. In other words, when the needle mat is used as the inorganic fiber aggregate, the inorganic fiber aggregate may or may not contain an organic binder and an inorganic binder.

(Binder attachment process)
In this step, a binder is attached to the inorganic fiber aggregate.
The binder may be an organic binder or an inorganic binder.
Examples of the organic binder include rubber-based resins, styrene-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, and polyurethane resins.
Examples of the inorganic binder include alumina sol, silica sol, aerogel, fumed silica, and titanium particles.

(Drying process)
In this step, the inorganic fiber assembly to which the binder is attached is dried.
The drying conditions are not particularly limited, but are preferably 50 to 300° C. and 1 to 20 minutes.

By carrying out the binder impregnation step and the drying step, the binder can be adhered to the inorganic fiber aggregate.
When an organic binder is applied, it is possible to prevent fibers from falling off and scattering from the inorganic fiber assembly.
When an inorganic binder is attached to the surface of the inorganic fibers, the contact pressure of the inorganic fiber aggregate can be improved, and therefore, when the manufactured inorganic fiber aggregate with inorganic sheet material is used in an exhaust gas purification device, the exhaust gas treatment body can be favorably held.

When the binder applying step and the drying step are performed, the drying step may be performed after the binder applying step, and then the inorganic sheet material arranging step may be performed.
Also, after the binder application step, the inorganic sheet material arrangement step may be performed, and then the drying step may be performed.
Also, after the inorganic sheet material arrangement step, a binder attachment step may be performed, and then a drying step may be performed.
Alternatively, the binder application step and the inorganic sheet material arrangement step may be carried out simultaneously, and then the drying step may be carried out.
That is, in the manufacturing method of an inorganic fiber aggregate with an inorganic sheet material according to the first embodiment of the present invention, the order of the binder attachment step and the inorganic sheet material arrangement step is not particularly limited.

Next, a method for producing an inorganic fiber aggregate by a papermaking method will be described.
The manufacturing method of an inorganic fiber aggregate with an inorganic sheet material, in which an inorganic fiber aggregate is produced by a papermaking method, includes an inorganic fiber-binder mixed liquid preparation step of mixing inorganic fibers and a binder to produce an inorganic fiber-binder mixed liquid, and a papermaking step of papermaking and dehydrating the inorganic fiber-binder mixed liquid to produce an inorganic fiber aggregate.
This method may further include an inorganic sheet material arranging step of arranging an inorganic sheet material on the inorganic fiber aggregate after the papermaking step.
In this method, in the papermaking step, the inorganic fiber aggregate may be paper-made on an inorganic sheet material.
Each step will be described below.

(Inorganic fiber-binder mixed liquid preparation process)
The inorganic fibers are opened, and the opened inorganic fibers are mixed with a binder to prepare an inorganic fiber-binder mixed liquid.
As the binder, both an organic binder and an inorganic binder are used.
Examples of the organic binder include rubber-based resins, styrene-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, and polyurethane resins.
Examples of the inorganic binder include alumina sol, silica sol, aerogel, fumed silica, and titanium particles.
If necessary, other components such as water may be added to the inorganic fiber-binder mixture.

The average fiber length of the inorganic fibers used in preparing the inorganic fiber-binder mixture liquid is preferably 0.1 to 20 mm.
If the average fiber length of the inorganic fibers is less than 0.1 mm, the fiber length of the inorganic fibers is too short, and the shape retention of the inorganic fiber aggregate obtained through the subsequent steps is reduced. Furthermore, when the inorganic fibers are made into a fiber aggregate, suitable entanglement does not occur between the inorganic fibers, making it difficult to obtain sufficient surface pressure.
If the average fiber length of the inorganic fibers exceeds 20 mm, the fiber length of the inorganic fibers is too long, and the inorganic fibers become too strongly entangled with each other during the papermaking process described below. As a result, when made into an inorganic fiber aggregate, the inorganic fibers tend to accumulate unevenly and the shear strength tends to decrease.

(Paper making process)
The inorganic fiber-binder mixture is poured into a molding machine having a filtering mesh formed on the bottom surface, and the water in the mixture is removed through the mesh to produce an inorganic fiber aggregate.

Next, a method for arranging an inorganic sheet material on an inorganic fiber aggregate in a manufacturing method for an inorganic fiber aggregate with an inorganic sheet material, in which an inorganic fiber aggregate is produced by a papermaking method, will be described.
In a manufacturing method for an inorganic fiber aggregate with an inorganic sheet material in which an inorganic fiber aggregate is produced by a papermaking method, a drying process for drying the inorganic fiber aggregate may be performed after the papermaking process, and an inorganic sheet material placement process for placing the inorganic sheet material on the inorganic fiber aggregate may be performed after the drying process.

In addition, in a method for producing an inorganic fiber aggregate with an inorganic sheet material in which an inorganic fiber aggregate is produced by a papermaking method, after the papermaking process, an inorganic sheet material arrangement process may be performed in which the inorganic sheet material is arranged on the inorganic fiber aggregate, and after the inorganic sheet material arrangement process, a drying process may be performed in which the inorganic fiber aggregate is dried.

In the drying step of the above method, the inorganic fiber aggregate produced in the papermaking step may be heated and pressurized. During the heating and pressurizing, a heat treatment may be performed in which hot air is passed through the inorganic fiber aggregate to dry it, or the inorganic fiber aggregate may be left in a wet state without being subjected to a heat treatment.
When heat treatment is performed, the heating temperature or hot air temperature is preferably 100 to 250°C to prevent deterioration of the organic binder due to heat. In the range of 100 to 250°C, moisture can be removed from the inorganic fiber aggregate while suppressing deterioration of the organic binder. If the heating temperature or hot air temperature is less than 100°C, the temperature does not reach the center of the inorganic fiber aggregate, and the drying time becomes long. Furthermore, if it exceeds 250°C, the organic binder is deteriorated and the binding force between the fibers is reduced, making it difficult to control the thickness of the inorganic fiber aggregate.

In other words, in a method for producing an inorganic fiber aggregate with an inorganic sheet material in which the inorganic fiber aggregate is produced by a papermaking method, the order of the drying process and the inorganic sheet material arrangement process after the papermaking process is not particularly limited.

In addition, in a manufacturing method for an inorganic fiber aggregate with an inorganic sheet material in which an inorganic fiber aggregate is produced by a papermaking method, during the papermaking process, an inorganic fiber-binder mixed liquid is placed on the inorganic sheet material, and then the inorganic fiber-binder mixed liquid is papermade and dehydrated to produce the inorganic fiber aggregate, and after the papermaking process, a drying process is performed to dry the inorganic fiber aggregate.
In this method, the inorganic fiber aggregate can be produced into a paper and at the same time, the inorganic sheet material can be disposed on the inorganic fiber aggregate.
When this method is carried out, it is preferable that the inorganic sheet material has a degree of liquid permeability that allows the liquid component to pass therethrough.

Next, a method for producing an exhaust gas purifying device using the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention will be described.
The manufacturing method of the exhaust gas purification device includes a winding step and a press-fitting step.

(Winding process)
In this step, the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention is wound around an exhaust gas treatment body prepared by a conventionally known method to produce a wound body.

(Press-fitting process)
Next, the prepared wound body is press-fitted into a metal casing.
In this case, the inorganic sheet material may be pressed in so that it is positioned closer to the exhaust gas inlet of the metal casing than the inorganic fiber aggregate, or the inorganic sheet material may be pressed in so that it is positioned closer to the exhaust gas outlet of the metal casing than the inorganic fiber aggregate.

Through the above steps, the exhaust gas purification device according to the first embodiment of the present invention can be manufactured.

(Example)
Hereinafter, examples will be given that more specifically disclose the inorganic fiber aggregate with inorganic sheet material according to the first embodiment of the present invention, but the present invention is not limited to these examples.

Example 1
(1) Inorganic fiber aggregate preparation process: A basic aluminum chloride aqueous solution was prepared so that the Al content was 70 g/l and the atomic ratio of Al:Cl was 1:1.8. Silica sol was then added to the aqueous solution so that the composition ratio of the inorganic _fibers after firing would be _Al2O3 : _SiO2 = 72:28 (weight ratio). An appropriate amount of organic polymer (polyvinyl alcohol) was then added to prepare a mixed solution.
The resulting mixture was concentrated to obtain a spinning mixture, which was then spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 5.1 μm.

Next, the alumina fiber precursor was compressed to produce a continuous sheet-like material.
The obtained sheet-like material was continuously needle-punched under the conditions shown below to prepare a needle mat.
First, a needle board was prepared on which needles were attached at a density of 21 needles/ ^cm2 . Next, this needle board was placed above one surface of a sheet-like material, and the needle board was moved up and down once along the thickness direction of the sheet-like material to perform needle punching processing to produce a needle mat. At this time, the needles were penetrated until the barbs formed at the tips of the needles completely protruded to the opposite surface of the sheet-like material.

The needle mat obtained was continuously fired at a maximum temperature of 1250°C to produce a fired sheet-like material made of inorganic fibers containing alumina and silica in a ratio of 72 parts by weight:28 parts by weight. The average fiber diameter of the inorganic fibers was 5.1 μm, and the minimum fiber diameter of the inorganic fibers was 3.2 μm. The fired sheet-like material thus obtained had a bulk density of 0.15 g/ ^cm3 and a basis weight of 1500 g/ ^m2 .
The obtained fired sheet-like product was cut to prepare a sheet-like inorganic fiber aggregate.
The obtained inorganic fiber aggregate had a longitudinal length of 364 mm and a lateral length of 50 mm, and had a rectangular shape in a plan view.

(2) Inorganic Sheet Material Preparation Step As an inorganic sheet material, a stainless steel sheet having a thickness of 0.04 μm and higher air resistance than an inorganic fiber aggregate was prepared.

(3) Inorganic Sheet Material Arrangement Step An inorganic sheet material made of stainless steel was arranged on one side surface formed along the longitudinal direction of the inorganic fiber aggregate, and an inorganic fiber aggregate with an inorganic sheet material according to Example 1 was produced.

Example 2
An inorganic fiber aggregate with an inorganic sheet material according to Example 2 was produced in the same manner as in Example 1, except that a copper foil having a thickness of 0.03 μm was used instead of the inorganic sheet material made of stainless steel.

(Comparative Example 1)
An inorganic fiber aggregate according to Comparative Example 1 was produced in the same manner as in Example 1, except that an inorganic sheet material made of stainless steel was not disposed.

<Gas flow rate test>
The gas flow rate (L/min) at the exhaust gas inlet and the gas pressure (kPa) at the exhaust gas inlet were measured by the following method.
A non-breathable test cylinder having a diameter of 103 mm was prepared, and the inorganic fiber aggregates with inorganic sheet material of Examples 1 and 2, and the inorganic fiber aggregate of Comparative Example 1 were wrapped around the side of the test cylinder so that the side of the inorganic fiber aggregate formed a circle, to produce a wound body.
Next, each wound body was press-fitted into a metal casing such that the distance (narrowed GAP) between the metal casing and the test cylinder was 4.0 mm and the packing density (GBD) of the inorganic fiber aggregate was 0.26 g/cm ^3. In addition, for the inorganic fiber aggregates with inorganic sheet material according to Examples 1 and 2, the side on which the inorganic sheet material was arranged was positioned on the exhaust gas inlet side.
Next, air was allowed to flow from the exhaust gas inlet of the metal casing, and the flow rate (L/min) of the gas on the exhaust gas inlet side and the gas pressure (kPa) on the exhaust gas inlet side were measured.
The results are shown in Table 1 and FIG.
FIG. 6 is a graph plotting the results of the gas flow rate test, with y being the gas flow rate (L/min) on the exhaust gas inlet side and x being the gas pressure (kPa) on the exhaust gas inlet side.

As shown in FIG. 6, in the gas flow rate test, the inorganic fiber assemblies with inorganic sheet material according to Examples 1 and 2 satisfy the following formula (1).
y<5.0x...(1)
From the above results, it was found that when the inorganic fiber aggregates with inorganic sheet material according to Examples 1 and 2 were used as a holding seal material for an exhaust gas purification device, the sealing property was improved.
Therefore, it was found that when an exhaust gas purification device is manufactured using the inorganic fiber aggregate with inorganic sheet material of Examples 1 and 2, the exhaust gas flowing in from the exhaust gas inlet of the metal casing can be prevented from passing through the inside of the inorganic fiber aggregate with inorganic sheet material and being discharged from the exhaust gas exhaust outlet of the metal casing.

Second Embodiment
The inorganic fiber aggregate with an inorganic sheet material according to the second embodiment of the present invention is an inorganic fiber aggregate with an inorganic sheet material used as a gasket.

FIG. 7 is a perspective view that illustrates an example of an inorganic fiber aggregate with an inorganic sheet material according to the second embodiment of the present invention.
FIG. 8 is a cross-sectional view that illustrates an example of a pipe in which an inorganic fiber aggregate with an inorganic sheet material according to the second embodiment of the present invention is used.

The inorganic fiber aggregate 110 with inorganic sheet material shown in FIG. 7 is composed of a sheet-like, single-layer inorganic fiber aggregate 120 and an inorganic sheet material 130 that has a higher air resistance than the inorganic fiber aggregate 120.

The inorganic fiber aggregate 110 with inorganic sheet material shown in Figure 7 is ring-shaped, and the inorganic sheet material 130 is arranged on the inner surface 121 of the inorganic fiber aggregate 120.

As shown in FIG. 8 , a cylindrical pipe 160 is made up of a first pipe 161 and a second pipe 162 .
A first flange 163 is formed at an end 161a of the first pipe 161, and a second flange 164 is formed at an end 162a of the second pipe 162. Further, a gasket space 165 for accommodating the inorganic fiber aggregate 110 with the inorganic sheet material is formed at the end 162a of the second pipe 162.
In the pipe 160, the first pipe 161 and the second pipe 162 are connected such that an end 161a of the first pipe 161 and an end 162a of the second pipe 162 are in contact with each other.
Furthermore, the first flange 163 and the second flange 164 are fixed together by a fastener 166 .

An inorganic fiber aggregate 110 with an inorganic sheet material attached is disposed in the pipe 160. When gas passes through the pipe 160, the gas collides with the inside of the inorganic fiber aggregate 110 with an inorganic sheet material attached.
Since the inorganic sheet material 130 is disposed in the inorganic fiber assembly 110 with the inorganic sheet material, gas does not easily pass through.
Therefore, in the pipe 160 , gas is less likely to leak from the connection portion between the first pipe 161 and the second pipe 162 .

In the inorganic fiber aggregate 110 with an inorganic sheet material, the inorganic sheet material 130 may be adhered to the inorganic fiber aggregate 120 by an adhesive, or may be fixed by another means.
The adhesive is not particularly limited, and may be an inorganic adhesive or an organic adhesive.

The inorganic fiber aggregate 110 with inorganic sheet material is compressed by applying pressure from above and below the inorganic fiber aggregate 110 with inorganic sheet material until the inorganic fiber aggregate 120 has a density of 0.3 g/ ^cm3 , and it is preferable that the vertical thickness of the inorganic fiber aggregate 110 with inorganic sheet material after relaxation for 20 minutes is 120% or more of the vertical thickness at the time of compression, and more preferably 150% or more.
The inorganic fiber assembly 110 with the inorganic sheet material having such characteristics has sufficient repulsive force and shape conformability, so that even if the second pipe 162 expands due to heat or the like and the gasket space 165 is deformed and widened, the inorganic fiber assembly 110 with the inorganic sheet material can conform to the shape.

The shape of the inorganic fiber aggregate 110 with inorganic sheet material is ring-shaped, but when the inorganic fiber aggregate with inorganic sheet material of the present invention is used for gasket applications, it is preferable that the shape be appropriately set to match the shape of the pipe.

In the inorganic fiber aggregate 110 with inorganic sheet material, the inorganic sheet material 130 is disposed on the entire inner surface 121 of the inorganic fiber aggregate 120, but the inorganic sheet material 130 may be disposed on the outer surface of the inorganic fiber aggregate 120. Moreover, the inorganic sheet material 130 may be disposed on only a portion of the inner surface and the outer surface of the inorganic fiber aggregate 120.
In either embodiment, gas is less likely to leak from the connection portion between the first pipe 161 and the second pipe 162 .

Next, each component of the inorganic fiber aggregate 110 with inorganic sheet material will be described.

(Inorganic fiber assembly)
The inorganic fiber aggregate 120 is not limited to a specific one, but may be a blanket subjected to needle punching treatment or an inorganic fiber aggregate obtained by a wet papermaking method.

For the inorganic fiber aggregate 120, silica-alumina ceramic fibers, crystalline fibers of alumina and mullite, silica fibers, etc. are used. In addition, for those that require low heat resistance, for example, those that are used at temperatures of 300°C or less, ultra-fine glass fibers can also be used.

It is more preferable that the fiber diameter of the inorganic fibers constituting the inorganic fiber aggregate 120 is 3 to 50 μm.

The inorganic fiber assembly 120 may contain an organic binder or an inorganic binder.
Examples of the organic binder include rubber-based resins, styrene-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, and polyurethane resins.
Examples of the inorganic binder include alumina sol, silica sol, aerogel, fumed silica, and titanium particles.
The organic binder can prevent fibers from falling off and scattering from the inorganic fiber assembly.
The inorganic binder adheres to the surface of the inorganic fibers, thereby improving the surface pressure of the inorganic fiber assembly, thereby enabling the exhaust gas treatment body to be favorably held.

(Inorganic sheet material)
The preferred materials constituting the inorganic sheet material 130 are the same as the preferred materials constituting the inorganic sheet material 30 described above.

1 Exhaust gas purification device 10, 110 Inorganic fiber aggregate with inorganic sheet material 20, 120 Inorganic fiber aggregate 21 First main surface 22 Second main surface 23 First side surface 24 Second side surface 25 First end 25a Convex portion 26 Second end 26a Concave portion 27 Through hole 28 Inner wall 30, 130 Inorganic sheet material 40 Exhaust gas treatment body 41 Cell 42 Cell wall 43 Sealing material 45 Non-permeable test cylinder 46 Winding body 50 Metal casing 51 Exhaust gas inlet 52 Exhaust gas outlet 121 Inner surface 160 of inorganic fiber aggregate Pipe 161 First pipe 161a End of first pipe 162 Second pipe 162a End of second pipe 163 First flange 164 Second flange 165 Gasket space 166 Fixing device

Claims (22)

A sheet-like single-layer inorganic fiber assembly;
an inorganic sheet material having a higher air resistance than the inorganic fiber aggregate;
the inorganic sheet material is disposed on at least a portion of a surface of the inorganic fiber aggregate,
The inorganic fiber assembly with an inorganic sheet material , wherein the inorganic sheet material is at least one selected from the group consisting of a foil and a plate . The inorganic fiber aggregate with inorganic sheet material according to claim 1, wherein the inorganic sheet material is made of at least one metal selected from the group consisting of stainless steel, aluminum, gold, silver, copper, iron, tin, titanium alloys and nickel alloys. The inorganic fiber aggregate with inorganic sheet material according to claim 1, wherein the inorganic sheet material is made of at least one inorganic material selected from the group consisting of alumina, silica, glass and biosoluble materials. 4. The inorganic fiber assembly with an inorganic sheet material according to claim 1, wherein the inorganic sheet material is made of a material having air permeability. The inorganic fiber aggregate with inorganic sheet material according to any one of claims 1 to 4, wherein pressure is applied from above and below to the inorganic fiber aggregate, the inorganic fiber aggregate is compressed until the density of the inorganic fiber aggregate becomes 0.3 g/ ^cm3 , and the thickness in the vertical direction of the inorganic fiber aggregate with inorganic sheet material after relaxation for 20 minutes is 120% or more of the thickness in the vertical direction at the time of compression. The inorganic fiber aggregate with inorganic sheet material according to any one of claims 1 to 5, wherein the inorganic fiber aggregate has a rectangular shape in a planar view having a longitudinal direction and a transverse direction, and has a first main surface, a second main surface opposite the first main surface, a first side surface formed along the longitudinal direction, and a second side surface opposite the first side surface. The inorganic fiber assembly with inorganic sheet material according to claim 6 , wherein the inorganic sheet material is disposed on at least a portion of any one of the first main surface, the second main surface, the first side surface, and the second side surface. 8. The inorganic fiber assembly with an inorganic sheet material according to claim 1, wherein the inorganic fiber assembly has through holes formed therethrough in a thickness direction. The inorganic fiber assembly with an inorganic sheet material according to claim 8 , wherein the inorganic sheet material is disposed on an inner wall of the through hole. The inorganic fiber assembly with the inorganic sheet material is
The inorganic fiber aggregate with inorganic sheet material according to any one of claims 1 to 9, which is used as the holding seal material of an exhaust gas purification device comprising an exhaust gas treatment body, a metal casing that houses the exhaust gas treatment body, and a holding seal material that is arranged between the exhaust gas treatment body and the metal casing. The inorganic fiber aggregate has a rectangular shape in a plan view having a longitudinal direction and a lateral direction, and has a first main surface, a second main surface opposite to the first main surface, a first side surface formed along the longitudinal direction, and a second side surface opposite to the first side surface,
An inorganic fiber aggregate with an inorganic sheet material according to any one of claims 1 to 10, wherein in the gas flow rate test described below, the gas flow rate (L/min) on the exhaust gas inlet side when the inorganic fiber aggregate with the inorganic sheet material is used and the gas pressure on the exhaust gas inlet side is 10 kPa is 80% or less of the gas flow rate (L/min) on the exhaust gas inlet side when the inorganic fiber aggregate without the inorganic sheet material is used and the gas pressure on the exhaust gas inlet side is 10 kPa.
Gas Flow Test:
An inorganic fiber assembly with an inorganic sheet material and an inorganic fiber assembly without an inorganic sheet material are prepared.
A non-breathable test cylinder is prepared, and an inorganic fiber aggregate with an inorganic sheet material and an inorganic fiber aggregate without an inorganic sheet material are each wound around the side of the test cylinder so that a first side of the inorganic fiber aggregate forms a circle, to produce a wound body.
Next, a cylindrical metal casing having an exhaust gas inlet and an exhaust gas outlet is prepared, and each wound body is pressed into the metal casing so that the inorganic sheet material is positioned closer to the exhaust gas inlet than the inorganic fiber aggregate and the packing density (GBD) of the inorganic fiber aggregate is 0.26 g/ ^cm3 .
Next, air is allowed to flow from the exhaust gas inlet of the metal casing, and the gas pressure (kPa) on the exhaust gas inlet side and the gas flow rate (L/min) on the exhaust gas inlet side are measured. The inorganic fiber assembly with an inorganic sheet material according to any one of claims 1 to 5 , wherein the inorganic fiber assembly with an inorganic sheet material is used as a gasket. A method for producing an inorganic fiber aggregate with an inorganic sheet material according to any one of claims 1 to 12 , comprising the steps of:
an inorganic fiber aggregate preparation step of assembling the inorganic fibers and then needle punching the aggregate to prepare a sheet-like, single-layer inorganic fiber aggregate;
and an inorganic sheet material disposing step of disposing an inorganic sheet material on at least a part of a surface of the inorganic fiber aggregate,
In the inorganic fiber aggregate with inorganic sheet material, the inorganic sheet material has a higher air flow resistance than the inorganic fiber aggregate,
The method for producing an inorganic fiber aggregate with an inorganic sheet material, wherein the inorganic sheet material is at least one selected from the group consisting of a foil and a plate . Furthermore, a binder impregnation step of impregnating the inorganic fiber aggregate with a binder;
The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 13, further comprising a drying step of drying the inorganic fiber aggregate to which the binder is attached. The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 14 , wherein the drying step is carried out after the binder applying step, and then the inorganic sheet material arranging step is carried out. The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 14 , wherein the inorganic sheet material arranging step is carried out after the binder applying step, and then the drying step is carried out. The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 14 , wherein the binder attaching step is carried out after the inorganic sheet material arranging step, and then the drying step is carried out. The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 14 , wherein the binder applying step and the inorganic sheet material arranging step are carried out simultaneously, and the drying step is carried out thereafter. A method for producing an inorganic fiber aggregate with an inorganic sheet material according to any one of claims 1 to 12 , comprising the steps of:
a step of preparing an inorganic fiber-binder mixed liquid by mixing inorganic fibers and a binder to prepare an inorganic fiber-binder mixed liquid;
and a papermaking process of papermaking and dehydrating the inorganic fiber-binder mixture to form an inorganic fiber aggregate.
The method includes a step of arranging an inorganic sheet material on the inorganic fiber aggregate after the papermaking step, or the papermaking step includes forming the inorganic fiber aggregate on an inorganic sheet material ,
The method for producing an inorganic fiber aggregate with an inorganic sheet material, wherein the inorganic sheet material is at least one selected from the group consisting of a foil and a plate . After the papermaking process, a drying process is performed to dry the inorganic fiber aggregate.
The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 19 , wherein the inorganic sheet material arranging step is carried out after the drying step. After the papermaking step, the inorganic sheet material arrangement step is carried out;
The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 19 , further comprising a drying step of drying the inorganic fiber aggregate after the inorganic sheet material arrangement step. In the papermaking process, the inorganic fiber-binder mixture is placed on the inorganic sheet material, and then the inorganic fiber-binder mixture is paper-made and dehydrated to produce the inorganic fiber aggregate;
The method for producing an inorganic fiber aggregate with an inorganic sheet material according to claim 19 , further comprising the step of drying the inorganic fiber aggregate after the papermaking step.

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