JP6974034B2 - Inorganic fiber molded body - Google Patents

Description

The present invention relates to an inorganic fibrous molded product having heat insulating properties used for a furnace wall material of various furnaces.

The inner surface of the furnace walls of various furnaces is made of refractory bricks and the like, and an inorganic fibrous molded body having heat insulating performance is installed on the outside of the refractory bricks and the like. As this inorganic fiber molded body, a _{molded body composed of a refractory ceramic fiber (amorphous fiber having an Al 2} O ₃ content of 40 to 60% by mass and a SiO ₂ content of 40 to 60% by mass) and a biosoluble fiber can be used. in use. For example, Patent Document 1 describes a fireproof heat insulating material composed of a ceramic fiber and an inorganic binder, in which the average fiber diameter of the ceramic fiber is 1.5 to 5 μm, and the total amount of non-fibrous particles contained in the ceramic fiber. Is 20% by weight or less of the whole fiber, the thermal conductivity at 600 ° C. is 0.060 to 0.090 W / (m · K), and the bulk density after drying is 250 to 400 kg / m ³ , bending at 600 ° C. A fire-resistant heat insulating material having a strength of 0.6 MPa or more (claim 1); a fire-resistant heat insulating material composed of a ceramic fiber, an inorganic binder, and an organic polymer flocculant, and has an average fiber diameter of the ceramic fiber. Is 1.5 to 5 μm, the total amount of non-fibrous particles contained in the ceramic fiber is 20% by weight or less of the whole fiber, and the thermal conductivity at 600 ° C. is 0.060 to 0.090 W / (m). -K), a fire-resistant heat insulating material having a bulk density of 150 to 300 kg / m ³ after drying and a bending strength of 0.8 MPa or more after drying (claim 3); the ceramic fiber is silica alumina. The fireproof heat insulating material (claim 5), which is a fiber, a silica alumina zirconia fiber or a biosoluble fiber, is disclosed.

Further, Patent Document 2 includes a heat insulating material (claim 1) containing an inorganic fiber, an inorganic particle, a clay mineral, a cationic flocculant and an anionic flocculant; the inorganic fiber is a biosoluble fiber. , Rock wool, alumina fiber, silica-alumina fiber or silica-alumina zirconia fiber (claim 3); the biosoluble fiber is the heat insulating material containing an alkali metal compound or an alkaline earth metal compound (claim). Item 4); The heat insulating material (claim 5); the clay mineral is at least one selected from the group consisting of kaolin, mullite, smectite, and bentonite; the inorganic particles are titanium oxide powder, silica powder, and alumina powder. And at least one selected from the group consisting of mullite powder, said heat insulating material (claim 7) is disclosed.

Further, Patent Document 3 describes a heat insulating material composed of an inorganic fiber having an average fiber diameter of 1.5 to 5.0 μm, fine particle silica and / or fine particle alumina, and inorganic powder particles, wherein the inorganic fiber is 25 to 25. Contains 40% by weight, 5 to 40% by weight of fine particle silica and / or fine particle alumina, 20 to 70% by weight of inorganic powder particles, bulk density of 300 to 600 kg / m3, 3-point bending strength of 0.3 MPa or more, 600. A heat insulating material having a thermal conductivity of 0.060 to 0.090 W / (m · K) at ° C. (claim 1); the inorganic fiber is an alumina fiber, a silica alumina fiber, or a silica alumina zirconia fiber. The heat insulating material (claim 3) which is a biosoluble fiber; the heat insulating material in which the inorganic powder particles are at least one selected from silica, alumina, titanium dioxide, zirconium silicate, zirconium oxide, and silicon carbide. (Claim 4) is disclosed.

Japanese Unexamined Patent Publication No. 2014-196878 Japanese Unexamined Patent Publication No. 2013-79665 JP-A-2015-36587

Since refractory ceramic fiber (RCF) such as silica-alumina fiber has excellent heat resistance and cost performance, a heat insulating material containing RCF has been widely used. However, RCF has been regulated in recent years due to concerns about its impact on health, and alternatives to other inorganic fibers are being considered. For example, biodegradable fibers such as alkaline earth silicate (AES) fibers and alumina fibers have been replaced.
However, biosoluble fibers such as AES fibers are inferior in heat resistance to RCF, the continuous use temperature of AES fibers is about 1150 ° C, and the maximum use temperature is only up to about 1300 ° C. I couldn't handle it. Further, since the alumina fiber has good heat resistance, the heat insulating material using the alumina fiber has good heat resistance, but since the alumina fiber is very expensive, it is composed only of the alumina fiber. The heat insulating material made of the inorganic fibrous molded body is very disadvantageous in terms of cost.

Therefore, an object of the present invention is to provide an RCF-free inorganic fibrous molded article that exhibits good heat resistance at 1400 ° C. and is excellent in cost performance.

As a result of diligent studies on the heat resistance of the inorganic fiber molded product using AES fiber and alumina fiber in combination, the present inventors set the mixing ratio of AES fiber and alumina fiber to a specific ratio, and the obtained inorganic fiber. We have found that when the composition ratio of the three components of Al ₂ O ₃ , Ca _{O and SiO 2 in} the molded product is within a specific range, they exhibit excellent heat resistance, and have completed the present invention.

That is, the inorganic fibrous molded body of the present invention is an inorganic fibrous molded body composed of 40 to 60% by mass of alkaline earth silicate fibers and 40 to 60% by mass of alumina fibers, and the composition of the inorganic fibrous molded body is Al ₂ O ₃ 35 to 55% by mass, CaO 10 to 20% by mass, SiO ₂ 30 to 45% by mass, Na ₂ O, K ₂ O, MgO, TiO ₂ and Fe ₂ O ₃ selected from the group. Alternatively, it is characterized in that it is in the range of 0 to 5% by mass of other components composed of two or more kinds.

Further, in the inorganic fibrous molded product of the present invention, the inorganic filler is divided by 5 to 60% by mass with respect to 100% by mass of the inorganic fiber composed of 40 to 60% by mass of the alkaline earth silicate fiber and 40 to 60% by mass of the alumina fiber. an inorganic fibrous molded body comprising the composition of the inorganic fibrous molded body _Al 2 _O 3 35 to 65 wt%, CaO5～20 _wt%, SiO 2 25 to 45 wt%, _Na 2 O, K It is characterized in that it is in the range of 0 to 5% by mass of one or more other components selected from the group consisting of ₂ O, MgO, TiO ₂ and Fe ₂ O _3.

According to the present invention, it is possible to obtain an inorganic fibrous molded product satisfying a maximum operating temperature of 1400 ° C. while suppressing the blending ratio of expensive alumina fibers, so that an RCF-free heat insulating material having excellent cost performance can be obtained. It can be suitably used as a furnace wall material of various furnaces.

The inorganic fibrous molded product of the present invention is characterized in that AES fiber, which is an inorganic fiber not subject to regulation, and alumina fiber are used in combination. As described above, the inorganic fiber molded body made of AES fiber alone cannot withstand the operating temperature of about 1400 ° C., and the inorganic fiber molded body made of alumina fiber simple has sufficient heat resistance. However, it is not worth the cost due to the relationship with the site where the inorganic fiber molded body is used, but according to the present invention, by using these in combination, the disadvantages of both can be complemented.

Here, the AES fiber is a heat-resistant inorganic fiber that is not subject to regulation and is a substitute fiber for RCF, and is an artificial mineral fiber mainly composed of _{SiO 2, CaO, and MgO.} AES fibers, the SiO ₂ from 50 to 82 wt%, include CaO + MgO 18 to 43 wt%, other has a composition containing _Al 2 _O 3, oxides such as TiO _2, the heat resistant temperature is about up to 1300 ° C. It is said that. The AES fiber used in the present invention is a bulk-like (cotton-like) fiber having a fiber diameter of 2 to 8 μm, preferably 3 to 5 μm, and a fiber length of about 0.1 to several mm. Further, the AES fiber used in the present invention is preferably one having a low MgO content, and preferably one having a CaO / MgO mass ratio of 3 to 15, preferably 5 to 10. This is because ASE fibers having a large CaO / MgO mass ratio tend to have better adhesion to alumina fibers in a high temperature range, and have a bondability to alumina fibers having high heat resistance, resulting in post-heat treatment. It is considered that the line shrinkage rate of is reduced.

The blending ratio of the AES fiber is in the range of 40 to 60% by mass, preferably 40 to 50% by mass. Here, if the blending ratio of the AES fiber is less than 40% by mass, the blending ratio of the alumina fiber increases accordingly, which is not preferable because it is not worth the cost, and if it exceeds 60% by mass, it is heat resistant. It is not preferable because the property is deteriorated and it cannot withstand use at 1400 ° C.

Next, the alumina fiber used in the inorganic fibrous molded body of the present invention has an Al ₂ O ₃ content of 70% by mass or more, preferably 80% by mass or more, more preferably 95% by mass or more, and a SiO ₂ content of 30% by mass or less. Fibers (including zero), preferably 20% by mass or less (including zero), more preferably 5% by mass or less (including zero), and alumina fibers within this range do not belong to the category of RCF. , Not subject to recent regulations. The blending ratio of the alumina fiber is in the range of 40 to 60% by mass, preferably 50 to 60% by mass.

The composition of the inorganic fibrous molded body having the above _{configuration,} Al ₂ O 3 35 to 55 wt%, preferably from 45 to 55 wt%, CaO10～20 wt%, preferably from 10 to 15 _wt%, SiO 2. 30 to One or more components 0-5 selected from the group consisting of 45% by weight, preferably 30-40% by weight, Na ₂ O, K ₂ O, MgO, TiO ₂ and Fe ₂ O _3. It is in the range of% by mass, preferably 0 to 4% by mass. Here, if _{the content of Al 2} O ₃ is less than 35% by mass, the heat resistance is lowered, which is not preferable, and since the blending amount of the alumina fiber is limited, the content of _{Al 2} O _{3 is high.} If it exceeds 60% by mass, it leads to an increase in cost and the original purpose cannot be achieved. Further, if the contents of CaO and SiO _{2 are too large or too small with respect to the content of Al 2} O _3, the heat resistance will be lowered, which is not preferable. Further, if one or more of the other components selected from the group consisting of _{Na 2} O, K ₂ O, MgO, TiO ₂ and Fe ₂ O _{3 exceeds 5% by mass, the heat resistance is adversely affected.} It is not preferable because it causes

The method for producing the inorganic fibrous molded product of the present invention composed of the AES fiber and the alumina fiber as described above is not particularly limited, and for example, a predetermined amount of the AES fiber, the alumina fiber and the fibrous molding aid are added to water. After adding to and stirring to disperse AES fibers and alumina fibers, a predetermined amount of molding aid other than fiber is added and further stirred, and the obtained raw material slurry is pressed using a molding mold. It can be obtained by dehydration molding and drying the obtained molded body.

Here, the amount of water used in the raw material slurry is in the range of 3 to 15 times, preferably 5 to 12 times, the solid content mass of the raw material. Further, as the molding aid, for example, cellulose pulp, starch, water glass and the like can be used. When using cellulose pulp or starch as a dried product, it is preferable to dissolve it in water in advance before use. In particular, in the case of cellulose pulp, beat it with a refiner or the like to thoroughly loosen the cellulose pulp fibers. It is preferable to use from. In this case, the standard of beating degree of cellulose pulp is in the range of 200 to 600 ml in Canadian standard freeness as the degree of drainage. The amount of the molding aid added is in the range of 1 to 10% by mass, preferably 2 to 8% by mass, based on 100% by mass of the total amount of the AES fiber and the alumina fiber.

According to another aspect of the inorganic fibrous molded product of the present invention, the inorganic filler is divided into 5 to 60% by mass, preferably 5 by mass, based on 100% by mass of the inorganic fiber composed of the AES fiber and the alumina fiber in the above-mentioned compounding ratio. It is contained in the range of ~ 45% by mass. Here, if the blending amount of the inorganic filler is less than 5% by mass in terms of the outer percentage with respect to 100% by mass of the inorganic fiber, it is not preferable because there is no blending effect of the inorganic filler, and if it exceeds 60% by mass. , It is not preferable because the amount of inorganic fibers is too small and the molded product becomes brittle. Examples of the inorganic filler include secondary clay such as secondary kaolin, aluminosilicate, wollastonite, alumina, silica, zircon and the like. The particle size of the inorganic filler is not particularly limited, but is, for example, in the range of 0.1 to 10 μm, preferably 0.5 to 5 μm. The particle size of the inorganic filler was measured by a laser diffraction type particle size distribution measuring device.

The composition of the inorganic fibrous molded body comprising inorganic fillers such as mentioned _above, Al ₂ O 3 35 to 65 wt%, preferably from 35 to 55 wt%, CaO5～20 wt%, preferably from 8 to 20% by weight, SiO ₂ 25 to 45 wt%, preferably from 25 to _40% by weight, _Na 2 O, K 2 O, MgO, one or two or more composed other selected from the group consisting of TiO ₂ and _Fe 2 _{O 3} The components are in the range of 0 to 5% by mass, preferably 0 to 4% by mass. Here, if _{the content of Al 2} O ₃ is less than 35% by mass, the heat resistance is lowered, which is not preferable, and if it exceeds 65% by mass, a large amount of the inorganic filler containing _{Al 2} O _{3 is used.} It is not preferable because it needs to be added. Further, if the contents of CaO and SiO _{2 are too large or too small with respect to the content of Al 2} O _3, the heat resistance will be lowered, which is not preferable. Further, if one or more of the other components selected from the group consisting of _{Na 2} O, K ₂ O, MgO, TiO ₂ and Fe ₂ O _{3 exceeds 5% by mass, the heat resistance is adversely affected.} It is not preferable because it may cause

The method for producing the inorganic fiber molded product of the present invention made of the inorganic fiber composed of the AES fiber and the alumina fiber as described above and the inorganic filler is not particularly limited, and for example, a predetermined amount of the AES fiber and the alumina fiber And, after adding a fibrous molding aid to water and stirring and dispersing, a predetermined amount of an inorganic filler and a non-fibrous molding aid are added and further stirred, and the obtained raw material slurry is used for molding. It can be obtained by press dehydration molding using the mold of the above and drying the obtained molded body.

Here, the amount of water used in the raw material slurry is in the range of 3 to 15 times, preferably 5 to 12 times, the solid content mass of the raw material. Further, as the molding aid, for example, cellulose pulp, starch, water glass and the like can be used. When using cellulose pulp or starch as a dried product, it is preferable to dissolve it in water in advance before use. In particular, in the case of cellulose pulp, beat it with a refiner or the like to thoroughly loosen the cellulose pulp fibers. It is preferable to use from. In this case, the standard of beating degree of cellulose pulp is in the range of 200 to 600 ml in Canadian standard freeness as the degree of drainage. The amount of the molding aid added is in the range of 1 to 10% by mass, preferably 2 to 8% by mass, based on 100% by mass of the total amount of the AES fiber and the alumina fiber.

The inorganic fibrous molded article of the present invention having the above-mentioned structure has an apparent density in ^{the range of 150 to 500 kg / m 3} , preferably 200 to 400 kg / m ³ , and has a linear shrinkage rate (1400 ° C.-). 3 hours) is 3% or less, preferably 2% or less.

Examples 1-2 and Comparative Examples 1-3
As AES fiber, _{the trade name of SiO 2} content 70 to 80% by mass and CaO + MgO content 18 to 25% by mass (CaO / MgO mass ratio 6 to 8: simple analysis result by EDS) Superwood HT Bulk (Shin Nihon Thermal Ceramics Co., Ltd.) As the alumina fiber, _{the trade name Denca Alsen Bulk B100 (Denca Co., Ltd.) having an Al 2} O ₃ content of 100% by mass was used, and as a molding aid, the coniferous cellulose pulp was previously dissolved in water at a concentration of 5% by mass and beaten. (Drainage degree: Canadian standard freeness about 400 ml) and industrial starch dissolved in 2% by mass concentration were used, and 7.5 times the solid content mass was added at the ratio shown in Table 1 below. After stirring, water was finally added so that the amount of water was 10 times the mass of the solid content, and the concentration was adjusted to obtain a raw material slurry having a solid content of about 17% by mass. The obtained raw material slurry was weighed so that the apparent density of the molded product after molding was about 300 kg / m ^3, and press dehydration molding was performed using a molding mold, and the obtained molded product was pressed and dehydrated at 105 ° C. 24. By drying for an hour, specimens of the inorganic fibrous molded article of the present invention and the comparative product having dimensions of 10 mm × 40 mm × 160 mm were obtained. The apparent densities of the obtained inorganic fibrous molded products are also shown in Table 1.
The apparent density is a value obtained by dividing the dry mass of the specimen by the volume obtained by measuring the dimensions of the specimen with a caliper.

Table 2 shows the results of measuring the shrinkage rate after heat treatment at 1400 ° C. for 3 hours and the results of component analysis by energy dispersive X-ray analysis (EDS) for the specimens of the inorganic fibrous molded product of the present invention and the comparative product. show. The analysis conditions for EDS are as follows: JDE-2300 Energy Dispersive X-ray Analyzer (JEOL Ltd.), Acceleration voltage: 20 kV, Magnification 100 times.
For the shrinkage rate after heat treatment at 1400 ° C for 3 hours, the length between the marked lines marked in advance on the specimen of 10 mm × 40 mm × 160 mm was measured with a caliper, and in an electric furnace controlled at 1400 ° C. After heat treatment for 3 hours, it was transferred to a desiccator, cooled to room temperature (25 ° C), and the length between the same marked lines was measured again and calculated by the following formula:
Shrinkage rate ΔL (%) = (L ₀ −L ₁ ) / L ₀ × 100
L ₀ : Length between marked lines before heat treatment L ₁ : Length between marked lines after heat treatment In addition, EDS is analyzed using a sample obtained by rubbing a part of the specimen with a mortar and pulverizing it. It is a thing.

Examples 3-14 and Comparative Examples 4-8
As AES fiber, _{the trade name of SiO 2} content 70 to 80% by mass and CaO + MgO content 18 to 25% by mass (CaO / MgO mass ratio 6 to 8: simple analysis result by EDS) Superwood HT Bulk (Shin Nihon Thermal Ceramics Co., Ltd.) the used, as alumina fiber, using _Al 2 _{O 3} content of 100 wt% of the trade name DENKA al Sen bulk B100 (Denka Corporation), as a secondary kaolin, SiO2 content of about 50 wt%, Al2 O3 content of about 33 wt% primary Using the trade name Himod SR (Keiwa Furnace Co., Ltd.) as an ingredient, and using Wollastonite (Kansai Matek Co., Ltd .: normal grade), it was previously dissolved in water at a concentration of 5% by mass as a molding aid and beaten. Using coniferous cellulose pulp (water drainage: Canadian standard freeness about 400 ml) and industrial starch dissolved in water at a concentration of 2% by mass, the ratio shown in Table 3 below is 7.5 times the solid content mass. After adding and stirring water, water was finally added and the concentration was adjusted so that the amount of water was 10 times the mass of the solid content to prepare a raw material slurry having a solid content of about 17% by mass. As a procedure, first, AES fiber, alumina fiber, and cellulose pulp are stirred and dispersed in water, and then wollastonite, secondary kaolin, and industrial starch are added in this order while continuing stirring, and the concentration is adjusted as a raw material. It was made into a slurry. The obtained raw material slurry was weighed so that the apparent density of the molded product after molding was about 300 kg / m ^3, and press dehydration molding was performed using a molding mold, and the obtained molded product was pressed and dehydrated at 105 ° C. 24. By drying for an hour, specimens of the inorganic fibrous molded article of the present invention and the comparative product having dimensions of 10 mm × 40 mm × 160 mm were obtained. The apparent densities of the obtained inorganic fibrous molded products are also shown in Table 3.

Table 4 shows the results of measuring the shrinkage rate after heat treatment at 1400 ° C. for 3 hours and the results of component analysis by energy dispersive X-ray analysis (EDS) for the specimens of the inorganic fibrous molded product of the present invention and the comparative product. show.

As described above, the inorganic fibrous molded product of the present invention has a small shrinkage rate under heating conditions of 1400 ° C. and has good heat resistance, and the blending amount of alumina fibers can be suppressed, so that the cost performance is good. Since it is excellent in quality and does not contain RCF, it can be suitably used as an RCF-free material in applications such as a heat insulating material for a furnace wall, which is expected to be used at about 1400 ° C.

Claims (1)

For 100% by mass of inorganic fiber consisting of 40 to 60% by mass of alkaline earth silicate fiber and 40 to 60% by mass of alumina fiber, secondary kaolin or wallastnite as an inorganic filler or both of them are divided by an outer ratio of 9.1 to 60. It is an inorganic fibrous molded product containing 0 to 33.3% by mass of secondary kaolin and 0 to 33.3% by mass of wallastnite, and the composition of the inorganic fibrous molded product is Al. ₂ O ₃ 35 to 65 wt%, CaO5~25 _wt%, SiO 2 25 to 45 _{wt%, Na 2 O, K 2} O, MgO, 1 kind selected from the group consisting of TiO ₂ and _Fe 2 _{O 3} or An inorganic fibrous molded product characterized by being in the range of 0 to 5% by mass of two or more other components.