JPH0791124B2 - Heat-expandable ceramic fiber composite - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-expandable ceramic fiber composite material which is used as a holding material for an automobile ceramic filter or a ceramic catalyst mainly composed of vermiculite mineral.

[0002]

2. Description of the Related Art For example, in an automobile exhaust pipe, a ceramic filter or a ceramic catalyst is used for purification such as reduction of nitrogen oxides in exhaust gas. In order to retain the ceramic catalyst and the like in the exhaust pipe, conventionally, a ceramic fiber is used as a fiber base material, and a thermal expansion layer is made of a vermiculite mineral and a small amount of an organic binder. Wood was used.

[0003]

By the way, when the exhaust gas is re-combusted in the ceramic filter or the ceramic catalyst, the reaction filter heats the ceramic filter or the ceramic catalyst to a high temperature of 800 to 1000 ° C. In the above-mentioned conventional holding material mainly composed of vermiculite mineral, the vermiculite mineral that expands when heated exhibits a characteristic of shrinking when exposed to a high temperature of 800 to 1000 ° C., and a ceramic catalyst or the like in a high temperature region. Retaining performance against tends to deteriorate, and if it is subjected to vibration or friction in that state, it is easily pulverized from a layered form to a powder form, and as a result,
There is a risk that the above-mentioned ceramic filter or ceramic catalyst may rattle or that the holding material may blow through.

The present invention has been made in order to solve the above-mentioned problems, and a blending layer of vermiculite mineral is formed.
To provide a heat-expandable ceramic fiber composite material capable of preventing exposure to a high temperature of 800 ° C. or more and ensuring a stable holding force for a ceramic filter or a ceramic catalyst even when used in a high temperature region. It is an object.

[0005]

To achieve the above object, a heat-expandable ceramic fiber composite material according to the present invention comprises a heat-expansion layer mainly composed of vermiculite mineral as a heat-expansion material and a heat-expansion layer mainly composed of ceramic fibers. At least a heat insulating layer that is stacked on the ceramic filter or ceramic catalyst contact surface side , and
Set the thickness of the heat layer to 20% to 70% of the total thickness
It was done.

The above-mentioned heat-expandable ceramic fiber composite material
There are, 30 the thickness of the thermal expansion layer for the entire thickness of the
It is preferably set to 80% .

[0007]

According to the present invention, a composite of a heat insulating layer mainly composed of ceramic fibers provided on at least a side of the thermal expansion layer which is in contact with the ceramic filter or the ceramic catalyst.
The ratio to the total thickness of the material is in the range of 800 to 1400 ° C.
20% at 800 ℃, 1000 ℃ assuming the ambient temperature
30% at 50% at 1200 ° C and 70% at 1400 ° C
In this way, by setting according to the operating temperature.
I, even ceramic filters and ceramic catalyst becomes a high temperature of 800 to 14 00 ° C. in reaction heat, the Bamikyu
The temperature to which the thermal expansion layer mainly composed of light minerals is exposed is set to 80
It can be kept below 0 ° C. Therefore, if the vermiculite mineral, which is the main constituent material of the thermal expansion layer, is 800
Prevents the retention of the ceramic filter or ceramic catalyst from being lowered due to the property of shrinking when exposed to a high temperature of ℃ or more, causing the ceramic catalyst to rattle or blow through even when used in a high temperature range. Can be held stably without any

Particularly, if the thickness of the thermal expansion layer is set to 30 to 80% of the total thickness, a certain holding force can be surely obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view showing one in which a heat-expandable ceramic fiber composite material according to an embodiment of the present invention is applied to an automobile ceramic filter or a ceramic catalyst holding material.

In FIG. 1, reference numeral 1 is a thermal expansion layer, 2 is a heat insulating layer mainly composed of ceramic fibers, and both 1 and 2 constitute a two-layered thermal expansion ceramic fiber composite material 3. The heat insulating layer 2 is stacked on at least the contact surface side of the thermal expansion layer 1 with the ceramic filter or the ceramic catalyst 4.

The structure of the thermal expansion layer 1 and the heat insulating layer 2 is
This will be described with reference to FIG. First, 8 ceramic fibers
A papermaking liquid A having a concentration of 1.5 wt% prepared by mixing 3 wt%, 5 wt% of sepiolite mineral and 12 wt% of an organic binder is prepared for a heat insulating layer. Further, a papermaking liquid B having a concentration of 1.5 wt% prepared by mixing 30 wt% of ceramic fibers, 4 wt% of sepiolite mineral and 54 wt% of vermiculite mineral is prepared for the thermal expansion layer.

Here, the preferable mixing ratio of the materials forming the heat insulating layer 2 and the thermal expansion layer 1 is as shown in FIG. In the heat insulating layer 2, since the ceramic fiber having heat resistance and heat insulating property is mainly used, the ceramic fiber is 60 w.
If it is less than t%, heat resistance and heat insulation are insufficient, and 95 wt.
If it exceeds%, the amount of the organic binder blended becomes small, and it becomes impossible to form a sheet. The main effect of the heat insulating layer is not lost even if the sepiolite mineral is not added, but it is a so-called inorganic binder, and the heat reinforcement effect can be improved by adding a small amount thereof. However, the compounding amount is 10 wt%
Beyond the above, the mixing ratio of the ceramic fiber decreases, the heat insulation of the mat is poor, and the sepiolite minerals entangle with other fiber materials at high temperature to act as a kind of binder, increasing the density of the mat. Reduce porosity. Therefore, the voids in the mat that hinder the heat conduction are reduced, and the heat insulation is impaired.

In the heat insulation layer 2, since the expansion property is not the main purpose, the vermiculite mineral may not be used in some cases, but when a large expansion amount is required from the low temperature of the entire mat, the vermiculite mineral is used. Three
The initial expansion characteristics can be improved by adding up to 0 wt%. However, the compounding amount of vermiculite mineral is 30
If it exceeds wt%, the heat deterioration rate of the heat insulating layer increases, and the holding power of the ceramic catalyst and the like decreases. The organic binder is at least 1-2 wt% for handling the mat after paper making.
However, if it exceeds 20 wt%, the heat resistance of the mat will be reduced.

Further, as shown in FIG. 3, the thickness of the heat insulating layer 2 is 800 ° C. according to the catalyst use temperature.
In order to keep the temperature below ° C, the range of 20 to 70% is applied. That is, the heat-expandable ceramic fiber composite of the heat insulating layer 2
The ratio to the thickness of the entire material 3 is 800 to 1400 ° C.
20% at 800 ° C, 1000, assuming operating temperature range
30% at ℃, 50% at 1200 ℃, 70% at 1400 ℃
For example, it is set according to the operating temperature.
The thickness of the heat-expandable layer 1 depends on the holding force required for the ceramic catalyst and the total thickness of the heat-expandable ceramic fiber composite 3
It is set in the range of 30 to 80% with respect to the body thickness .

In the thermal expansion layer 1, the fiber base material is preferably used in an amount of 10 to 60 wt% in order to increase the blending ratio of the vermiculite mineral exhibiting the thermal expansion characteristics. 10 wt%
If it is less than 60% by weight, the heat resistance of the base material is too low.
If it exceeds, the expansion property is deteriorated. Although the addition of a small amount of sepiolite mineral can improve the heat-resisting effect, if the blending amount exceeds 10 wt%, the blending ratio of the ceramic fiber will decrease, and the heat insulating property of the mat will be inferior. It entangles with other fiber materials at high temperature and acts as a kind of binder, increasing the density of the mat and decreasing the porosity. Therefore, the voids in the mat that hinder the heat conduction are reduced, and the heat insulation is impaired.

The blending amount of vermiculite mineral is 30 wt.
If it is less than 90%, the expansion characteristics are insufficient, and if it exceeds 90% by weight,
The amount of the fibrous base material, the binder, etc., is reduced, which hinders the mat making process, and all the organic binder is burned out at high temperatures, resulting in a significant decrease in strength so that the initial shape cannot be retained. The organic binder needs to be at least 1 to 2 wt% in order to improve the handleability of the mat after paper making,
If it exceeds 20 wt%, the heat resistance of the mat will decrease.

On the other hand, 19 wt% of ceramic fiber, 71 wt% of vermiculite mineral, and 10 wt% of organic binder.
%, A papermaking liquid C having a concentration of 1.5 wt% was prepared for the thermal expansion layer, and the ceramic fiber 70 was used.
A papermaking liquid D having a concentration of 1.5 wt% prepared by mixing wt%, 20 wt% of vermiculite mineral, and an organic binder in a mixing ratio of 10 wt% is prepared for a heat insulating layer.

As the ceramic fiber, an aluminosilicate, for example, SC126OD2 (trade name, manufactured by Nippon Steel Chemical Co., Ltd.), vermiculite mineral, unexpanded vermiculite 0 treated with sodium ammonium hydrogenphosphate, and sepiolite mineral, Milcon MS-2. −
2 (trade name, manufactured by Showa Mining Co., Ltd.) and Sumikaflex 900 (trade name, manufactured by Sumitomo Chemical Co., Ltd.) were used as organic binders.

A method for producing a heat-expandable ceramic fiber composite material as Example 1 using the above papermaking liquids A and B will be described. First, as shown in FIG. 4, a papermaking tub 13 having a lower end opening having a papermaking net 11 and a baffle plate 12 which is located above the papermaking net 11 and which can be inserted and removed is prepared, and 25 l of the papermaking liquid A is injected into the papermaking tub 13. After that, 50 l of the papermaking liquid B is injected through the baffle plate 12 so that the water surface of the papermaking liquid A is not disturbed. After that, the baffle plate 12 is gently pulled out and then water is squeezed to insulate the heat insulating layer 2 corresponding to the papermaking liquid A and the papermaking liquid B.
To obtain a paper product obtained by combining the thermal expansion layers 1 corresponding to. Next, this paper product is dried and pressed to produce a heat-expandable ceramic fiber composite material 3 having a thickness of 5 mm and a basis weight of 5000 g / m ² .

[0020] The papermaking solution C, and using the D, and a method of fabricating a thermal expansion ceramic fiber composite as an embodiment 2 will be described. First, after injecting 25 liters of the papermaking liquid D into the papermaking tub 13, 50 liters of the papermaking liquid D is injected through the baffle plate 12 so that the water surface of the papermaking liquid C is not disturbed, and then the baffle plate 1
2 is drawn out and then squeezed to obtain a paper product in which the heat insulating layer 2 corresponding to the papermaking liquid D and the thermal expansion layer 1 corresponding to the papermaking liquid C are combined. Next, this paper product is dried and pressed to produce a heat-expandable ceramic fiber composite material 3 having a thickness of 5 mm and a basis weight of 5000 g / m ² .

Further, using the above-mentioned papermaking solution B, a heat-expandable ceramic fiber composite material as a comparative example is manufactured. That is, after injecting 75 l of the papermaking liquid B into the papermaking tub 13, water is squeezed to obtain a heat-expandable material. This is dried and pressed to produce a heat-expandable ceramic fiber composite material having a thickness of 5 mm and a basis weight of 5000 g / m ² .

Each of the heat-expandable ceramic fiber composite materials of Examples 1 and 2 was wound around the ceramic catalyst 4 with the heat insulating layer 2 side facing inward. Then, as shown in FIG. A cover was made to make a catalyst assembly. Similarly, the heat-expandable ceramic fiber composite material of the comparative example was wrapped around the ceramic catalyst, and then the casing 14 was covered to prepare a catalyst assembly.

Next, a heating test is performed on each of the catalyst assemblies of Examples 1 and 2 and the catalyst assembly of the comparative example by using a heating test apparatus equipped with a thermocouple 15 and gas burners 16 and 17, as shown in FIG. It was That is, the temperature on the outer peripheral side of the ceramic catalyst 4 in each catalyst assembly is 1000 ° C.
The gas burners 16 and 17 were heated so as to be about the same level, and this heating state was maintained at 3 hours.

After heating the above 3 hours, after cooling it, FIG.
The holding power for the ceramic catalyst 4 was measured by the holding power measuring device shown in FIG. That is, the holding force was measured by applying a compression force of 50 mm / min to the ceramic catalyst 4 via the load cell 19 while the catalyst assemblies were supported by the extraction pipe 18.

Then, each of the above catalyst assemblies was held in the vibration container 20 of the vibration test apparatus shown in FIG.
mm, vibration frequency of 290 reciprocations / min.
After continuing r, the holding force was measured again in the same manner as above. FIG. 9 shows the holding force after the vibration test when the holding force after heating was 100.

As is clear from the holding power index of FIG.
The comparative example has a high rate of contraction of the vermiculite mineral in the thermal expansion layer, and the layered morphology collapses due to the vibration test and is pulverized into powder, resulting in a remarkable decrease in the holding power.
On the other hand, since Examples 1 and 2 have the heat insulating layer 2 mainly composed of ceramic fibers, the reduction of the expansion force due to the contraction of the vermiculite mineral in the thermal expansion layer 1 is suppressed, and therefore, It can be seen that the layered form is effectively maintained even after the vibration test.

Since the heat-expandable ceramic fiber composite material 3 is obtained by integrating the heat-expansion layer 1 and the heat insulation layer 2 by combining the paper-making liquids, the labor for assembling does not increase, and the production is performed. Is also easy to proceed. However, it is also possible to form the composite body by making the thermal expansion layer 1 and the heat insulation layer 2 separately, drying them, and then pressing and pressing them.

The heat insulating layer 2 may be provided not only on the contact surface side of the thermal expansion layer 1 with the ceramic filter or the ceramic catalyst 4, but also on the opposite surface side as shown in FIG.

[0029]

As described above, according to the present invention, a thermal expansion layer mainly composed of vermiculite mineral and ceramic fibers are stacked on at least the contact side of the thermal expansion layer with the ceramic filter or the ceramic catalyst. A heat insulating layer , and the entire thickness of the heat insulating layer is
By composite material having a two-layer structure was set at 20% to 70% of the thickness of the ceramic filters and ceramic
The catalyst heats up to 800-1400 ℃ due to heat of reaction
Also, the thermal expansion layer mainly composed of the above vermiculite mineral
The exposure temperature can be suppressed to less than 800 ° C. Shi
Therefore, Ki out to prevent a reduction in expansion forces of thermal expansion layer due to shrinkage characteristics of the vermiculite mineral which is a main constituent material of the thermal expansion layer, even when used at a high temperature region of more than 8 00 ° C, the ceramic catalyst It is possible to stably secure the holding power for the like.

In particular, as in claim 2, the thickness of the thermal expansion layer
Is set to 30 to 80% with respect to the total thickness, so that when used in a high temperature range, the ceramic catalyst is not
It is possible to more reliably and reliably exert the holding force to be exerted.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a heat-expandable ceramic fiber composite material applied to an automobile ceramic filter or a ceramic catalyst holding material according to an embodiment of the present invention.

FIG. 2 is a table showing the composition of a papermaking liquid for a heat-expandable ceramic fiber composite material.

FIG. 3 is a table showing a thickness range of a heat insulating layer with respect to a catalyst use temperature.

FIG. 4 is a structural diagram of a paper making tub used when manufacturing a heat-expandable ceramic fiber composite material.

FIG. 5 is an external view showing a catalyst assembly.

FIG. 6 is a block diagram showing a heating test apparatus for a catalyst assembly.

FIG. 7 is a configuration diagram showing a holding force measuring device for a catalyst assembly.

FIG. 8 is a block diagram showing a vibration test apparatus for a catalyst assembly.

FIG. 9 is a table showing a holding force index after a vibration test.

FIG. 10 is a diagram showing another configuration of the heat-expandable ceramic fiber composite material.

[Explanation of symbols]

 1 Thermal expansion layer 2 Thermal insulation layer 4 Ceramic filter or ceramic catalyst

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F01N 3/28 311 N

Claims (2)

[Claims] 1. A thermal expansion layer mainly composed of vermiculite mineral as a thermal expansion material, and a heat insulation layer mainly composed of ceramic fibers and laminated on at least a ceramic filter or a ceramic catalyst contact surface side of the thermal expansion layer , and The thickness of the heat insulating layer is 20 with respect to the total thickness.
% To 70%, which is a thermally expansive ceramic fiber composite material. 2. A thermal expansion of claim 1, the thickness of the thermal bulging脹層is set to 30% to 80% relative to the overall thickness of the ceramic fiber composite.