JP2002114580A - Heat-resistant laminated body, method for manufacturing heat resistant laminated body and heat resistant filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant laminated body and a method for manufacturing the laminated body having such heat resistance that the body can be used at >=1000 deg.C and having high dust collecting efficiency, and to provide a heat-resistant filter formed from this heat-resistant laminated body. SOLUTION: The heat-resistant laminated body consists of a plurality of inorganic fiber sheets having inorganic fibers containing alumina laminated in the thickness direction and an inorganic adhesive impregnating the inorganic fiber sheets to adhere the inorganic fiber sheets. The proportion of alumina in the inorganic fibers is 60 to 99.5 mass % of the whole inorganic fibers. The bulk density of the heat-resistant laminated body is 0.1 to 0.8 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a heat-resistant laminate formed by bonding a plurality of inorganic fiber sheets to each other via an inorganic adhesive, a method for producing the same, and a heat-resistant filter formed from the heat-resistant laminate. About.

[0002]

2. Description of the Related Art It has been known that a filter using an inorganic fiber sheet is advantageous in that it can be used at a relatively high temperature. Such a filter is expected as a general industrial filter or a filter for an engine exhaust gas of a diesel engine or the like for the purpose of capturing dust of relatively high-temperature exhaust gas (gas), that is, purifying the gas.

For example, Japanese Patent Application Laid-Open No. 6-304918 discloses a method in which an inorganic fiber sheet is wound around a shrinkable core material with an adhesive therebetween, dried, and then the shrinkable core material is extracted. A method for producing a hollow inorganic molded article is disclosed. The inorganic molded product can be used as a filter as described above. As the shrinkable core material, a cellulosic core, for example, a paper core (paper tube) can be used.

According to this method, it is easier to produce a thin-walled hollow molded product than a method in which a composition obtained by kneading a raw material containing inorganic fibers, clay, and the like is extruded by an extruder. Excellent in point. Also, since the hollow molded product manufactured by this method is a method of winding a preformed inorganic fiber sheet around a shrinkable core material, it has a certain degree of strength, and is excellent in strength even when thin. Inorganic molded articles can be manufactured.

Further, a shrinkable core material that shrinks by drying is used. When the inorganic fiber sheet is wound around the shrinkable core material with an adhesive interposed therebetween and then dried, the shrinkable core material simultaneously shrinks. Therefore, since the shrinkable core material can be extracted without applying a large external force, even if the inorganic molded product is thin, it can be easily manufactured without damaging the inorganic molded product.

The above publication discloses that one or more types of inorganic fibers such as silica-alumina fiber, glass fiber, alumina fiber, silica fiber, and carbon fiber are used as fibers constituting the inorganic fiber sheet. I have. The inorganic fiber sheet is defined as containing 50% by weight or more of inorganic fibers. If necessary, heat-resistant fibers such as aromatic polyamide fibers and polyamide-imide fibers, or recycled fibers, semi-synthetic fibers, and synthetic fibers And the like may be included.

Examples of the adhesive include inorganic adhesives such as aqueous sols of inorganic oxides such as silica sol, alumina sol and zirconia sol, and cements such as alumina cement, magnesia cement and zirconia cement. Examples of the organic adhesive include ethyl silicate, silica sol in which the solvent is alcohol, and the like. In addition, the viscosity of the liquid containing the adhesive is 10 to 2,000 cps so that the inorganic fiber sheet is easily impregnated and the sheets are easily bonded to each other.
Is preferred.

Further, when winding the inorganic fiber sheet around the shrinkable core material, even if the inorganic fiber sheet is uneven,
It is also described that, when wound into layers or more and laminated together, an inorganic molded article having a uniform strength distribution as a whole can be obtained. It should be noted that since the above-mentioned adhesive may include an organic adhesive, it does not disclose performing heat baking (a treatment usually performed at a high temperature of 550 ° C. or more) at the time of bonding.

A heat-resistant laminate using the above-mentioned inorganic fiber sheet (inorganic paper) is disclosed in Japanese Patent Application Laid-Open No. 9-21.
No. 100 is also disclosed. This inorganic paper laminate is usually obtained by impregnating and adhering an inorganic adhesive and an organic adhesive to two inorganic papers, and then laminating the two to obtain a wet laminate, and drying the wet laminate. After letting
It can be manufactured by performing heat treatment and bonding two sheets of paper. The temperature of this heat treatment is 300 ° C. to 12 ° C.
It is described that the range of 00 ° C. is good.

However, since it is assumed that an organic adhesive is used in combination, only an example of heat treatment at 400 ° C. is actually disclosed. On the other hand,
Japanese Patent Application No. -108823 discloses a filter device including a heat-resistant tubular filter formed of heat-resistant fibers. In this filter device, a heating wire is integrally disposed on a surface of a tubular fiber tissue body (heat-resistant tubular filter) formed of heat-resistant fibers, and a passage direction of a fluid to be filtered of the tubular fiber tissue body is provided. A heat-resistant and air-permeable heat insulating material is arranged on the downstream side along the tubular fiber structure. With such a structure, when burning the deposits deposited on the filter, it is possible to efficiently burn with a small amount of heat, which is advantageous for the regeneration of the filter.

[0011] In this filter device, the fluid to be filtered is passed from the opposite side of the heat insulating material disposed along the tubular fibrous structure toward the heat insulating material with one end closed. Used. Then, while the fluid passes through the tubular fibrous structure, impurities in the fluid are collected by the tubular fibrous structure. When the heating wire is energized, the heating wire generates heat, and the sediment collected in the tubular fiber structure burns. In addition, since the heating wire is integrally disposed on the surface of the tubular fiber structure, the heat generated by the heating wire is efficiently transmitted to the sediment on the tubular fiber structure, and the heat insulation disposed on the downstream side. Due to the heat retaining effect of the material, the sediment burns efficiently with a small amount of heat.

As the material of the tubular fiber structure, a material woven as a single-layer plain woven fabric is used. The fibrous structure is formed from ceramic fibers such as silicon carbide fibers and alumina fibers.

[0013]

However, the above-mentioned publication discloses a heat-resistant laminate having high heat resistance and high dust collection efficiency usable at 1,000 ° C. or higher, and such a heat-resistant laminate Are not disclosed. For example, as a heat resistant filter,
It is required that the strength does not fall below a predetermined level even after use for a predetermined time at 0 ° C.

On the other hand, from the results of the research conducted by the present inventors, in the heat-resistant laminate used as the material of the heat-resistant filter, the constituent materials such as the material of the fiber used and the physical properties (such as bulk density) of the laminate are appropriately determined. It turns out that the above-mentioned problem cannot be solved without selecting it.

[0015] The present invention has been made in view of such problems of the related art, and has as its object the heat resistance that can be used at a temperature of 1,000 ° C or more,
An object of the present invention is to provide a heat-resistant laminate having high dust collection efficiency and a method for producing the same, and a heat-resistant filter formed from such a heat-resistant laminate.

[0016]

Means for Solving the Problems According to the present invention, a plurality of inorganic fiber sheets comprising inorganic fibers containing alumina and laminated in a thickness direction, and the inorganic fiber sheets are impregnated. And an inorganic adhesive for bonding the inorganic fiber sheets to each other, wherein the alumina content contained in the inorganic fibers is 60 to 99.5% by mass based on the entire inorganic fibers. ,
And the bulk density of the heat-resistant laminate is 0.1 to 0.8 g /
cm ³ is provided.

At this time, the heat-resistant laminate has an inner diameter of 3
After heating at 1,000 ° C. for 24 hours, the heat-resistant laminate formed into a 3 mm ring or cylindrical shape,
It is preferable that the O-ring compression strength measured at room temperature (about 25 ° C.) and at a compression speed of 2 mm / min is in the range of 0.3 to 8 MPa.

Further, according to the present invention, there is provided the method for producing a heat-resistant laminate, wherein the plurality of inorganic fiber sheets are impregnated with the inorganic adhesive, and the inorganic fiber sheets are laminated with each other. Is formed, the precursor is added to 550
A method for producing a heat-resistant laminate, characterized in that the laminate is heated to a temperature in the range of 〜1,000 ° C. and fired.

Further, according to the present invention, there is provided a heat-resistant filter formed from the above-mentioned heat-resistant laminate and having a plate-like or cylindrical shape.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A heat-resistant laminate of the present invention comprises inorganic fibers containing alumina, a plurality of layers of inorganic fiber sheets laminated in the thickness direction, and impregnated in the inorganic fiber sheets, In a heat-resistant laminate comprising an inorganic adhesive for bonding inorganic fiber sheets to each other, the alumina content contained in the inorganic fibers is 60 to 99.5% by mass based on the entire inorganic fibers, and the heat resistance is high. The bulk density of the laminate is 0.1 to 0.8 g / cm ³ . That is, the heat-resistant laminate of the present invention has a high heat resistance because a plurality of layers of inorganic fiber sheets having a high alumina content are laminated together and bonded to each other via an inorganic adhesive.

At this time, the heat-resistant laminate of the present invention preferably has an alumina content of 60 to 99.5% by mass contained in the inorganic fibers. This is because the alumina content is 6
When the amount is less than 0% by mass, when used at a high temperature of 1,000 ° C. or more, the strength of the heat-resistant laminate (for example, the O-ring compressive strength as described later) decreases, and the practical limit (usually 0.6 M
(Pa or more) and the heat-resistant laminate may be damaged during use. On the other hand, the alumina content is 99.
If it exceeds 5% by mass, it is difficult to suppress the crystal growth (increase in crystal size) of alumina during the production of the fiber. The crystal size of alumina contained in the inorganic fibers tends to increase excessively at high temperatures, but if the crystal size increases excessively, the inorganic fiber sheet becomes brittle and the heat-resistant laminate may be damaged during use. is there. Therefore, from such a viewpoint, the content of alumina contained in the inorganic fibers is preferably 61 to 95% by mass, particularly preferably 62 to 9% by mass.
It is preferably 0% by mass.

In order to effectively prevent the above-mentioned embrittlement, the inorganic fibers preferably contain silica in addition to alumina. At this time, the content of silica with respect to the entire inorganic fibers is usually 0.1 to 35% by mass, preferably 1 to 32% by mass, and particularly preferably 10 to 30% by mass. In particular, when the content of silica is 10% by mass or more,
By further adding boron oxide, the above embrittlement can be more effectively prevented. The content of boron oxide is usually 0.1 to 20% by mass, and preferably 1 to 15% by mass, based on the entire alumina-containing fiber.

The bulk density of the heat-resistant laminate of the present invention is preferably 0.1 to 0.8 g / cm ³ .
This is because if it is less than 0.1 g / cm ³ , the dust collection efficiency is reduced, and it may not be possible to use it as a heat resistant filter. In particular, the dust collection efficiency is reduced in an environment having a relatively high dust concentration (for example, the concentration of dust particles is 0.07 g / m ³ or more). The concentration may not reach a predetermined level (usually 60% or more). On the other hand, 0.8 g / cm ³
When it exceeds, the dust collection efficiency is good, but the air permeability (air permeability) tends to decrease. The decrease in air permeability increases the rate of rise of the differential pressure during fluid filtration, so that the life of the heat-resistant filter is reduced, and the filter must be regenerated or replaced immediately after being used for a relatively short time. From such a viewpoint, the bulk density of the heat-resistant laminate is preferably set to 0.1.
15 to 0.6 g / cm ³ , particularly preferably 0.2 to 0.5
g / cm ³ .

Note that the differential pressure means a pressure loss when a fluid passes through a filter, and is a pressure difference between a fluid pressure before filtration and a fluid pressure after filtration. In addition, the air permeability is usually represented by a fluid filtration rate at a predetermined differential pressure (usually 12.7 mm water column). The filtration rate is a value obtained by dividing (dividing) the processing flow rate (or the amount of passing fluid) by the area of the heat-resistant laminate that comes into contact with the fluid. These values can be measured with a normal flow meter or a filter test device.

Further, the heat resistance of the heat-resistant laminate of the present invention is such that the heat-resistant compressive strength (O-ring compressive strength) is 0.3 to 8
It is preferably in the range of MPa. This is because if the heat-resistant compressive strength is less than 0.3 MPa, there is a risk of breakage during use. On the other hand, the heat resistant compressive strength is 8 MPa
If it exceeds 300, the flexibility of the heat-resistant laminate will be reduced, and it will be difficult to mold into a cylindrical filter, and workability may be reduced. When the content of the adhesive is too large, the O-ring compressive strength becomes relatively high, but the amount of the adhesive is too large and
When the ring compressive strength is high, the air permeability may be reduced. From the above viewpoints, the heat-resistant compressive strength (O-ring compressive strength) is preferably 0.33 to 6 MPa, and particularly preferably 0.35 to 5 MPa.

The heat resistant compression strength is 33 m in inner diameter.
The O-ring compressive strength was measured using a heat-resistant laminate molded into a ring or a cylinder of m as a sample. After heating such a sample at 1,000 ° C. for 24 hours, measurement is performed at room temperature (about 25 ° C.) at a compression rate of 2 mm / min. Also,
The O-ring compressive strength is the compressive strength (also called radial crushing strength) when a cylindrical or ring-shaped object is compressed in the radial direction. Normally, the value is obtained from a load-displacement curve obtained when an O-ring-shaped test piece is sandwiched between compression jigs with its radial direction coinciding with the vertical direction and pressed from above and below in the vertical direction. At this time, the O-ring compressive strength is given by the following equation (Equation 1).
Given by

[0027]

(Equation 1)

The following references can be referred to for details of such compressive strength. (Reference 1) p5-49 in Mark Standard Handbook for
Mechanical Engineers, 9 ^th edition (Reference 2) G.DeWith, "Note on the Use of the Di
ametral Compressiontest for the Strength Measureme
nt of Ceramic ", J. Mater. Sci. Lett., 3 [11] 1000-100
2 (1984)

From the above, the heat-resistant laminate of the present invention has the above-described characteristics, and is particularly suitable as a material for forming a heat-resistant filter. Such a heat resistant filter is a plate filter or a tubular filter. The cylindrical filter can be manufactured by applying the above-mentioned conventional method. Details of the heat resistant filter will be described later.

(Production method of heat-resistant laminate) The heat-resistant laminate of the present invention can be preferably produced as follows. First, an inorganic fiber sheet containing alumina at a predetermined content is prepared. Next, the inorganic fiber sheet is impregnated with an inorganic adhesive. After impregnating the plurality of inorganic fiber sheets with the adhesive liquid, the undried inorganic fiber sheets are laminated together.

Here, a case where a cylindrical laminated body that can be used as a cylindrical hollow filter is formed will be described as an example. First, an adhesive impregnated inorganic fiber sheet is wound around a cylindrical core having a predetermined outer diameter. Note that the outer diameter of the cylindrical core material is substantially equal to the inner diameter of the cylindrical laminated body. The winding method of the sheet may be such that a plurality of sheets overlap each other in the thickness direction of the sheet (thickness direction of the cylindrical laminated body).
A spiral winding may be used.

The flat winding is a method of winding a sheet along the outer peripheral direction of a core material. That is, when the length of the sheet (the dimension along the winding direction) is larger than the outer peripheral length of the core material, almost the entire surface of the wound sheet is bonded to the back surface of the same sheet.

If a predetermined number of laminations cannot be obtained by winding one sheet, after the winding of one sheet is completed, the winding end of the second sheet is brought into contact with the winding end of the sheet. Similarly, start winding the second sheet. Similarly, when two or more sheets are used, a predetermined number of sheets are wound and the precursor of the heat-resistant laminate of the present invention is completed.

The core material is usually a pipe made of paper or plastic. This is because the core material is burned out at the firing stage, and it is not necessary to remove the core material as in the above-described conventional method. The adhesive is applied onto the inorganic fiber sheet using an applicator such as a roll coater, a knife coater, and a curtain coater, or is impregnated into the inorganic fiber sheet using an impregnation coater or an impregnation pan.

Next, the precursor obtained as described above is dried. Drying is preferably performed so as to remove most of the solvent (mainly water) of the dispersion liquid of the adhesive before the firing operation. Drying is usually performed at a temperature of room temperature (about 25 ° C.) or more and 80 ° C. or less. The drying time is not particularly limited, but is usually 20 hours to 5 days.

Finally, the dried precursor is fired to complete the production of the heat-resistant laminate of the present invention. In the firing, the precursor is heated, a plurality of inorganic fiber sheets laminated on each other are bonded, and a predetermined heat-resistant compressive strength (O-ring compressive strength: 0.8
To 6 MPa).

Therefore, the firing temperature and time are appropriately determined depending on the type and content of the adhesive. The firing temperature is usually in the range of 550 to 1,000 ° C, preferably 600 to 900 ° C. If the firing temperature is too low, a predetermined compressive strength may not be achieved, while if it is too high, the fibers contained in the inorganic fiber sheet may become brittle, resulting in a decrease in compressive strength. The firing time is usually 1 to
6 hours.

In the method for producing a laminate as described above, the adhesive strength between the inorganic fiber sheets can be increased as much as possible, and the compressive strength of the completed laminate can be effectively increased.
Therefore, it is possible to use a relatively thin fiber sheet. That is, even if the number of laminations is relatively large, the thickness (thickness) of the laminate does not unnecessarily increase. By increasing the number of laminations, it is possible to effectively realize a high toughness of the laminate (it does not crack like a normal ceramic) and a uniform strength.

When the above-mentioned laminate is used as a filter, dust collection efficiency can be effectively increased.
From such a point of view, the thickness of the inorganic fiber sheet is usually 0.1 mm.
It is 1 to 0.6 mm, preferably 0.2 to 0.5 mm.
When the above laminate is used as a filter, the number of laminates is usually 5 to 50, and preferably 10 to 30.

(Inorganic Fiber Sheet) The inorganic fiber sheet used in the present invention is usually made of an inorganic fiber non-woven fabric having a thickness of less than 1 mm, and can be easily obtained from the market in the form of felt or paper. . Further, as described above, the inorganic fiber sheet needs to include inorganic fibers containing a predetermined amount of alumina, but may also include other fibers. Other fibers are usually inorganic fibers such as silica fibers and carbon fibers.

Usually, the inorganic fiber sheet contains an organic binder for bonding the fibers, but preferably does not contain organic fibers. Even if such an organic material is contained, it is burned off at the above-mentioned firing temperature or the use temperature of the heat-resistant laminate. The bulk density of the inorganic fibrous sheet (before lamination) is usually 0.10~0.25g / cm ^3, preferably a 0.15~0.20g / cm ^3. The inorganic fiber sheet has fibers of irregular length (typically 0.1 m).
(having a length of from m to several tens of mm), and fibers containing fibers whose lengths are substantially uniform. For the latter containing fibers with uniform lengths, use continuous filaments as they are, or cut continuous filaments, use fibers whose lengths are almost uniform, and use them to form a nonwoven fabric. Form. When using fibers obtained by cutting continuous filaments, the length is
Usually 3 mm to 30 mm, preferably 7 to 15 mm,
The variation in length (the difference between the longest and the shortest)
Usually, it is 10% or less.

When the fibers having the same length as described above are used, the porosity of the inorganic fiber sheet can be effectively increased. When fibers of various lengths are present, short fibers enter the gaps between the long fibers, and an inorganic fiber sheet having a relatively small porosity is likely to be formed. Such a sheet hardly occurs in a sheet using fibers of uniform length, and a sheet having a relatively high porosity can be obtained. Therefore, in order to produce a laminate having a lighter specific gravity, it is particularly advantageous to use a sheet formed using inorganic fibers made of fibers having a length substantially equal to a constant size. That is, when an inorganic fiber sheet containing an inorganic fiber substantially consisting of fibers having substantially the same length obtained by cutting continuous continuous fibers or continuous continuous fibers so as to have a certain length is used. Effectively reduce the specific gravity of the heat-resistant laminate,
The air permeability can be effectively increased.

To give a specific example, an inorganic fiber sheet “trademark: Nextel, product name: Non-Woven Paper Series” manufactured by 3M Co., Ltd. can be used. Alumina = 62% by mass), product number 440 (alumina = 70% by mass), product number 55
0 (alumina = 73% by mass), product number 610 (alumina>
99% by mass), product number 720 (alumina = 85% by mass) and the like can be suitably used. This “Trademark: Nextel”
The series includes inorganic fibers consisting essentially of fibers whose lengths are aligned to about 12.7 mm.

(Inorganic Adhesive) The inorganic adhesive used in the present invention adheres a plurality of laminated inorganic fiber sheets to each other by baking (heat treatment) at a predetermined temperature to obtain a predetermined heat resistant compression strength (O-ring compression strength). The strength is not particularly limited as long as a laminate having strength can be produced. For example, aqueous sols of inorganic oxides such as silica sol, alumina sol and titania sol, and dispersions containing finely divided vermiculite powder can be used.

The vermiculite pulverized fine powder is excellent in that a laminate having high compressive strength can be produced in a relatively small amount. On the other hand, among inorganic oxide sols, alumina sol is
When used for a relatively long time in a use environment exceeding 1,000 ° C., the laminate is excellent in that the compressive strength of the laminate can be stably maintained at a high level. Further, the silica sol is excellent in that the air permeability (air permeability) of the laminate can be maintained high even when a relatively large amount is used.

Here, the usage form of the inorganic adhesive is an aqueous liquid having a predetermined viscosity. The viscosity is usually preferably 1 to 2,000 cps (mPa · s) so that the inorganic fiber sheet can be easily impregnated and the sheets can easily adhere to each other. The solid content (adhesive component) concentration of the aqueous adhesive liquid is usually 1 to 25% by mass, preferably 2 to 20% by mass. If the solid content concentration is too high, the viscosity of the aqueous liquid may be too high, and impregnation into the inorganic fiber sheet may be difficult, and the air permeability of the completed laminate may decrease. On the other hand, if the solid content (adhesive component) concentration is too low, a laminate having a sufficient compressive strength may not be obtained.

The amount of the inorganic adhesive to be impregnated is usually 5 to 55% by mass, preferably 10 to 50% by mass, particularly preferably 12 to 45% by mass, based on the whole laminate.
It is. If the amount of the inorganic adhesive is too small, the uniformity of the toughness and strength of the laminate may not be effectively improved, while if the amount is too large, the air permeability of the laminate is reduced or the weight of the laminate is reduced. This can be difficult. Further, the adhesive for impregnating the sheets and bonding the sheets together usually comprises an inorganic adhesive, and preferably does not include an organic adhesive.

(Heat Resistant Filter) The heat resistant filter of the present invention can be formed from a heat resistant laminate as described above. The heat resistant filter of the present invention can be used in the same manner as a conventional tubular filter. For example, if you place a heater inside,
It can be used as a filter capable of collecting combustible powder, incineration removal, and regeneration. In addition, since the filter itself is hard and can maintain strength by itself, other components for maintaining strength and maintaining shape, such as a metal support, are unnecessary.

Also, by appropriately changing the bulk density and the number of layers, it is easy to adjust the collection efficiency, the collection amount, the pressure loss, and the like, so that it can be used in various applications. For example, it can be used as a filter for diesel engine exhaust gas (for collecting and removing soot). In this case, the maximum allowable value of the pressure loss is preferably in the range of 7 to 40 KPa. The collection efficiency may be 60 to 80%, and there is a tendency that the reduction in pressure loss is more important than the improvement in collection efficiency in order to reduce the load on the engine. For example, the filtration speed is designed to be about 100 m / min or more. The air permeability is preferably about 10 cm ³ / (cm ² · second) or more.

In the case of diesel engine exhaust gas, the regeneration method when the filter is clogged is as follows.
Soot incineration with an electric heater is preferred. Furthermore, in order to reduce the amount of electricity (extend the regeneration interval), it is desirable that the amount of soot stored in the filter body be large. Therefore, it is better that the porosity is large (the bulk density is small). On the other hand, when used as an environmental dust filter or a general powder capture filter, the maximum allowable value of pressure loss is 2 to 1
A range of 0 KPa is particularly preferred.

The collection efficiency of the heat resistant filter of the present invention is as follows:
Usually, it is preferably 90% or more and almost 100%.
A relatively low pressure loss is required from the viewpoint of the exhaust capacity of the ventilation fan, and a high collection efficiency is required from the viewpoint of emission control. Therefore, the air permeability and the filtration speed need not be so high, and the filtration speed is usually 1 to 2.5 m /
The minute and air permeability are usually 3 to 4 cm ³ / (cm ² · second).
If the air permeability is high, it is difficult to obtain a high collection efficiency.

As a method for regenerating the filter when the filter is clogged, a cleaning method using pulse gas is used. Therefore, since the pulse is sprayed by the high-pressure gas, the impact strength is required. On the other hand, if the thickness of the filter is excessively large, dust that has entered the inside of the filter cannot be swept outward with a pulse. Therefore, the heat-resistant laminate of the present invention, which can provide a high-strength product even though its thickness is relatively thin, is suitable for such a filter application.

The use temperature of the heat-resistant filter of the present invention is usually 400 ° C. or more and the maximum use temperature of the inorganic fiber sheet (usually 1,200 to 1,400 ° C.).

[0054]

EXAMPLES The present invention will be described in more detail based on examples, but the present invention is not limited to these examples. (Example 1) In this example, a heat-resistant filter made of a heat-resistant laminate was produced as follows. First, 710mm x 35
mm strip of inorganic fiber sheet (“Trademark: Nextel 312 Non-Woven Paper”)
I prepared it. Separately, 6 g of distilled water was added to 24 g of alumina sol "Product No. 200" manufactured by Nissan Chemical Industries, Ltd., and the mixture was sufficiently stirred to prepare a dispersion liquid having an inorganic adhesive component concentration of 8% by mass.

The inorganic fiber sheet is composed of 62% by mass of alumina, 24% by mass of silica, and 1% of boron oxide (B ₂ O ₃ ).
It was formed from a nonwoven fabric obtained by binding alumina-based fibers having a chemical composition of 4% by mass with an organic binder and a silica binder. The bulk density of the inorganic fiber sheet was 0.18 g / cm ³ , and the maximum use temperature was 1,200 ° C.

The above dispersion liquid was placed in a stainless steel pan, and the two inorganic fiber sheets were immersed. While immersing the inorganic fiber sheet in the dispersion liquid, the inorganic fiber sheet was flat-wound around a paper tube having an outer diameter of 28 mm. After the winding of one inorganic fiber sheet, the end of the winding and the starting end of the second sheet were brought into contact with each other, connected, and wound in the same manner as the first sheet. After the second inorganic fiber sheet was wound, without drying the paper tube, it was dried in a room at room temperature for 2 days to obtain a dried laminate precursor. The number of layers counted in the thickness direction was 14 to 15.

The dried laminate precursor was placed in an electric furnace and calcined at 700 ° C. for 4 hours to produce a heat-resistant filter comprising the heat-resistant laminate of this example. The dimensions of the filter are
Outer diameter 35.1mm, wall thickness 3.5mm, cylinder length 35mm
Met. The amount of the inorganic adhesive was 31.5% by mass based on the entire heat-resistant laminate. Further, the bulk density of the laminate was 0.32 g / cm ³ .

The heat-resistant filter produced as described above
On the other hand, a filter tester model 8110 manufactured by TSI was used.
And the collection efficiency was measured. The result is shown in FIG. What
The measurement conditions were as follows. Measurement conditions: surface velocity = 9.6 m / min, dust particles = salt, particles
Particle size (center value of mass) = 0.1 μm, particle concentration = 0.
1g / m^Three, Initial air permeability = 6.9 cm^Three/ (Cm ^Two・ Second)

As a result of the measurement, the saturation collection rate was almost 100%
And reached 100% in about 10 minutes. Also,
The pressure loss (differential pressure) during the measurement of the collection efficiency was always 0.1 atm (10 kPa) or less, and the air permeability did not deteriorate.

Example 2 A tubular heat-resistant filter of this example was produced in the same manner as in Example 1, except that the outer diameter of the paper tube was changed to 33 mm and the width of the inorganic fiber sheet strip was changed to 25 mm.
This filter had an outer diameter of 41.6 mm and a wall thickness of 4.1 mm, and the number of layers counted in the wall thickness direction was 12 to 13.
The O-ring compression strength of the filter of this example was measured. O-ring compressive strength (without heating at 1,000 ℃)
It was 1.2 MPa. The O-ring compression strength was a value measured under the conditions of normal temperature (about 25 ° C.) and a compression speed of 2 mm / min. The apparatus used for the measurement was a universal tester “Model: RTC-1325A” manufactured by Orientec Co., Ltd.
Met. Next, in order to evaluate the heat resistance, the heat-resistant filter was heated at 1,000 ° C. for 24 hours, and the O-ring compression strength (heat-resistant compression strength) after heating was measured. The measurement conditions were the same as above. The heat resistant compression strength of the heat resistant filter of this example was 1.1 MPa.

(Example 3) An adhesive dispersion was applied to a Silkasol "trade name: Snowtex UP" 20 manufactured by Nissan Chemical Industries, Ltd.
g, and diluted with 20 g of distilled water (adhesive component concentration = 10% by mass), and the drying conditions and the sintering conditions were changed as follows, in the same manner as in Example 2, except that Example heat resistant filters were made. The drying was performed at room temperature for 16 hours and then at 60 ° C. for 8 hours. In addition, firing is 6
Heat at 00 ° C. for 5 hours. The amount of the inorganic adhesive was 35.3% by mass based on the entire heat-resistant laminate. Further, the bulk density of the laminate was 0.32 g / cm ³ , and the initial air permeability measured in the same manner as in Example 1 was 10.6 cm / cm ^3.
3 / (cm ² · second). About the heat resistant filter of this example, the O-ring compression strength (1, 0
(Without heating at 00 ° C.) and heat resistant compression strength. O-ring compression strength is 1.6 MPa, heat-resistant compression strength is 1.5 Pa
Met.

Example 4 An adhesive dispersion was applied to WRGrace
& Co. (USA) vermiculite dispersion "Trademark: Micro
Lite963 ”was prepared in the same manner as in Example 3, except that 20 g of distilled water was added to 20 g of distilled water and diluted. The amount of the inorganic adhesive was 15.2% by mass based on the entire heat-resistant laminate. further,
The bulk density of the laminate was 0.22 g / cm ^3.
The initial air permeability measured in the same manner as described above is 6.5 cm ³ /
(Cm ² · sec). About the heat resistant filter of this example, the O-ring compression strength (1, 0
(Without heating at 00 ° C.) and heat resistant compression strength. O-ring compression strength is 1.6 MPa, heat-resistant compression strength is 1.5 Pa
Met.

Example 5 The adhesive component concentration was 16% by mass.
A heat resistant filter of this example was produced in the same manner as in Example 3, except that the filter was changed to. The bulk density of the laminate is 0.43 g / cm
^{Was 3} . The O-ring compressive strength (without heating at 1,000 ° C.) of the heat-resistant filter of this example measured in the same manner as in Example 2 was 3.3 MPa.

(Example 6) Except that the adhesive dispersion was changed to "Snowtex S" manufactured by Nissan Chemical Industries, Ltd.
In the same manner as in Example 3, the heat-resistant filter of this example was manufactured. The bulk density of the laminate was 0.32 g / cm ³ . About the heat resistant filter of this example, O
The ring compression strength (without heating at 1,000 ° C.) was 0.6 MPa.

(Example 7) An adhesive dispersion was changed to an alumina sol (product number) 520 manufactured by Nissan Chemical Industries, Ltd.
In the same manner as in Example 3, the heat-resistant filter of this example was manufactured. The bulk density of the laminate was 0.33 g / cm ³ . About the heat resistant filter of this example, O
The ring compression strength (without heating at 1,000 ° C.) was 0.8 MPa.

(Example 8) Except that the outer diameter of the paper tube was changed to 31.5 mm, and a polypropylene nonwoven fabric (0.16 mm thick) was wound and laminated between the inorganic fiber sheets laminated with each other. In the same manner as in Example 3, the heat-resistant filter of this example was manufactured. After sintering, when the cross section of the filter was observed (using a magnifying glass of 50 times), the polypropylene nonwoven fabric was burned out, and a space was formed between each layer of the inorganic fiber sheet where the polypropylene nonwoven fabric was present. The reason why the non-woven fabric that can be burned off is used as described above is to make it easier to control the bulk density of the laminate within a relatively small range. The amount of the inorganic adhesive was 37.4% by mass based on the entire heat-resistant laminate, and the bulk density of the laminate was 0.29.
g / cm ³ . About the heat resistant filter of this example, the O-ring compressive strength (1,000 ° C
(Without heating) was 0.39 MPa.

[0067]

As is apparent from the above description, according to the present invention, a heat-resistant laminate having both heat resistance usable at a temperature of 1,000 ° C. or more and high dust collection efficiency, and production thereof A method and a heat resistant filter formed from such a heat resistant laminate can be provided.

[Brief description of the drawings]

FIG. 1 is a graph showing the dust collection efficiency of a heat resistant filter in Example 1.

Claims (5)

[Claims] 1. An inorganic fiber sheet comprising an inorganic fiber containing alumina and laminated in a thickness direction with a plurality of layers, and an inorganic adhesive impregnated in the inorganic fiber sheet and bonding the inorganic fiber sheets to each other. Wherein the alumina content of the inorganic fibers is 60 to 99.5 mass% with respect to the entire inorganic fibers, and the bulk density of the heat-resistant laminate is: A heat-resistant laminate having a weight of 0.1 to 0.8 g / cm ³ . 2. The ring-shaped or cylindrical heat-resistant laminate having an inner diameter of 33 mm is heated at 1,000.degree. C. for 24 hours, then at room temperature (about 25.degree. C.) and at a compression speed of 2 m.
O-ring compressive strength measured at m / min 0.3 to 8 MPa
The heat-resistant laminate according to claim 1, wherein 3. The heat-resistant laminate according to claim 1, wherein the inorganic fibers are substantially composed of fibers having substantially the same length. 4. The method for producing a heat-resistant laminate according to claim 1, wherein the plurality of inorganic fiber sheets are impregnated with the inorganic adhesive, the inorganic fiber sheets are laminated with each other, and a precursor is formed. After formation, the precursors are 550-1.0
A method for producing a heat-resistant laminate, wherein the laminate is heated to a temperature in the range of 00 ° C. and fired. 5. A heat-resistant filter formed of the heat-resistant laminate according to any one of claims 1 to 3, and having a plate-like or cylindrical shape.