JPH0218300B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for forming a ceramic fiber structure used as a filling material or a sealing material for a furnace wall. [Prior art and problems to be solved by the invention] Ceramic fibers are generally used as high-temperature insulation materials at temperatures of 500 to 1300°C. It is necessary to attach it to the furnace wall etc. in a compressed state. However, it is difficult to uniformly fill the entire narrow spaces such as joints in a compressed state because the ceramic fibers are soft and weak, and there are also problems with the resilience after filling. Therefore, several attempts have been made to impart thermal expandability to ceramic fiber sheets to improve filling, sealing, and restoring properties after heating. As an example, according to Japanese Patent Application Laid-open No. 105319/1983,
It is disclosed that after vacuum packing ceramic fibers and attaching them to a furnace wall surface, etc., the vacuum packing is removed, and the fibers are expanded by the restoring force and filled between joints and the like. However, according to this method, the ceramic fibers are compressed in a certain direction using a vacuum pack, so there are certain restrictions on the shape and dimensions, and it is difficult to adjust the dimensions depending on the object to be attached. It was hot. On the other hand, JP-A-50-55603
According to the publication, it is disclosed that heat-expandable mica (vermiculite) is mixed into ceramic fibers, and a wet paper-formed sheet is used as a heat-expandable sheet. However, in the above sheet, vermiculite thermally decomposes at 1100 to 1150°C, and the thermally decomposed vermiculite reacts with the surface of the ceramic fiber and melts, losing heat resistance, and the temperature exceeds 1260°C, which is the normal temperature of ceramic fiber. There are drawbacks that make it unusable. Furthermore, since the sheet is molded by a so-called wet method, drying costs are required, which increases manufacturing costs. The present invention eliminates and eliminates such drawbacks of the prior art.
The above object is achieved by providing a method for forming a ceramic fiber structure that has excellent dimensional accuracy and heat resistance and can be easily manufactured for structures of any shape. It is something to do. [Means for Solving the Problems] The method for forming a ceramic fiber structure of the present invention includes:
With organic adhesive that softens when heated
After arranging a molded body of ceramic fiber compression molded to a bulk density of 0.1 to 0.3 g/cm ² at a predetermined location, the ceramic fiber is restored by heating to a temperature higher than the softening temperature of the organic adhesive. Features. That is, the present invention provides a ceramic fiber molded body that can expand approximately twice as much when heated in a direction perpendicular to the fiber arrangement plane, and can be used not only as a high-temperature insulating material but also as a filler or other sealing material as a spacer for the furnace wall. This is a method of forming a ceramic fiber structure that is expected to have a sealing effect as well. Hereinafter, the method for forming the ceramic fiber structure of the present invention will be specifically explained based on drawings and examples. The ceramic fiber used in the structure of the present invention is obtained by heating and melting a mineral raw material mainly composed of silica and alumina at high temperature to form a fibrous material by blowing or spinning. This is a generally well-known method in which a molded article in which fibers are arranged in layers is obtained by collecting the fibers by suctioning air through a net. In this respect, conventional spacers are also made from a similar molded body. According to the present invention, the molded body has a bulk density of 0.1 to
It is maintained in a compressed state in the range of 0.3g/ ^cm3 , and for this purpose an organic adhesive whose main component is a thermoplastic resin that softens and has fluidity in the temperature range of 100 to 350℃. It is necessary to mold the fibers in a restrained state so that they have the above-mentioned bulk density. This will be specifically explained based on the drawings as follows. FIG. 1 is an explanatory diagram showing the state of entanglement of fibers in a ceramic fiber molded body. In this figure, fibers 1 are intertwined with each other and scattered in each direction.
There is a void 〓2 between the fibers. This molded body has a bulk density of 0.1 to 0.3, most preferably 0.13 to 0.20 g/
When 2 to 15 parts by weight of the organic adhesive is uniformly applied to the surface of the fibers and dried, 100 parts by weight of ceramic fibers compressed to a volume of 100 cm ³ are obtained.
As shown in the enlarged explanatory view of the ceramic fiber molded article in FIG. 2, the fibers 1 are arranged in a fixed direction, and the inter-fiber spaces 2 are extremely small. When the fibers are no longer restrained by the organic adhesive, they return to the fiber state of the molded article shown in FIG. This principle can be explained as follows. first,
The bulk density of the fibers used in the sheet material used in the molded product is approximately
0.08g/cm ³ , but the bulk density is 0.16g/cm ³
Table 1 shows the results of measuring the recovery rate of the fibers of the molded product by compressing the volume to one-half so that the compressed state was heated at various temperatures to dissolve the molded product.

[Table] As is clear from Table 1, the recovery rate when the volume of the fibers of the molded body shown in Figure 1 is compressed to half is the highest in the range of 200 to 300℃, which is more than double. ,
It becomes smaller when the temperature exceeds 400℃. Therefore 100～
We newly discovered that it is optimal to use an organic adhesive that softens when heated at 350℃ and loses its binding force on the fibers. A molded article can be produced based on this knowledge, and the necessary conditions for this purpose are as follows. The first condition is that the ceramic fibers of the molded body are laminated in layers and that the average length of the fibers is 50 mm or more.
The reason for this is that when the average length of the fibers is 50 mm or less, the bulk density increases, the air space between the fibers decreases, and the expansion rate due to restoration decreases, resulting in an inappropriate fiber state. The second condition is that the laminated ceramic fibers are uniformly applied to the fiber surface with an organic adhesive whose main component is a thermoplastic resin that softens and exhibits fluidity in the temperature range of 100 to 350°C. It is necessary to constrain the fibers so that the bulk density is 0.1 to 0.3 g/cm ³ . The reason for this is that if the bulk density is 0.1 g/cm ³ or less, the fiber state will be similar to that shown in FIG. 1, and it will not exhibit restorability even when heated. On the other hand, if the bulk density is 0.3 g/cm ³ or more, the fibers will be in a broken state and will not have any expansion ability even when heated. As described above, according to the present invention, when the heat treatment temperature of the molded article reaches 350°C, the organic adhesive that binds the fibers softens and becomes fluid, and the restrained state of the fibers is released. As shown in Figure 1, the ceramic fibers are in a fibrous state, so compared to the restrained fibers, the ceramic fibers are in a fibrous state in a direction perpendicular to the layered arrangement plane.
It will expand 2.2 times. In this way, the molded body expands by heating in the direction perpendicular to the layered arrangement plane of the ceramic fibers, so if it is used as a spacer between the joints of a layered single block of ceramic fibers with the joints closed by thermal expansion, Unlike conventional expansible mica-containing molded products, which expand in all directions when heated, this product is ideal as a spacer to be inserted between joints. On the other hand, according to the present invention, in the molded article, the content of the organic adhesive is 100% of the ceramic fiber.
The amount is preferably 2 to 15 parts by weight. The reason is that if the content is less than 2 parts by weight, the fibers cannot be restrained by the organic adhesive.
This is because, while the fibrous state shown in FIG. 2 will not occur, if the amount exceeds 15 parts by weight, the expansion of the molded product due to heating of the ceramic fibers will be inhibited. Taking these things into consideration, the optimal condition is that the content of the organic adhesive is 4 to 8 parts by weight per 100 parts by weight of ceramic fiber, and the bulk density of the molded product is 0.13 to 0.20.
It is important to restrain the fibers so as to obtain the fiber state shown in ^FIG . Examples of the present invention will be specifically described below. Example 1 A bulk of ceramic fibers collected and laminated in layers was impregnated with a 10wt% aqueous solution of SBR latex emulsion with a minimum film forming temperature of 8°C, and formed by vacuum suction, and the ceramic fibers were impregnated with the liquid. A molded body was obtained by dehydration and drying to a ratio of 0.55 times. The properties of this molded body were as shown in Table 2.

[Table] When the obtained compact was filled into the joints of the furnace wall of a 1000°C furnace and used as a spacer, it exhibited sufficient heat insulation and sealing properties as a sealing material during regular use, improving the thermal efficiency and durability of the furnace. . Example 2 Minimum film forming temperature when fiberizing by blowing method
Spray an aqueous solution of 5 wt% acrylic resin emulsion at 45℃ in the same weight amount based on the amount of hot water released, and apply it uniformly to the fibers.
A bulk of ceramic fibers laminated in layers with a water content of about 10 wt% was pressed while the layers were compressed, and dried as it was to obtain a molded body.
In this case, since the amount of sprayed liquid is so small that it does not contain any water at the time of estimation, it is impossible to do so because the adhesive effect of the resin will be lost. The properties of the molded product at this time were as shown in Table 3.

〔Effect of the invention〕

As described above, the method for forming the ceramic fiber structure of the present invention can produce a compression-molded ceramic fiber compact that is as inexpensive as general dry ceramic fiber sheets such as blankets and felts, and is easy to process. Because it was installed and then restored by heating, it is a heat-resistant sealing material that can be used at high temperatures.
This is an optimal method for forming fillers and is industrially useful.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing the fiber state of a conventional ceramic fiber molded article, and FIG. 2 is an enlarged explanatory diagram showing the fiber arrangement state of a thermally expandable ceramic fiber molded article according to the present invention. In the drawings, 1 is a ceramic fiber and 2 is a space between the fibers.

Claims (1)

[Scope of Claims] 1. After arranging at a predetermined location a ceramic fiber molded body compression-molded to a bulk density of 0.1 to 0.3 g/cm ² using an organic adhesive that softens when heated, A method for forming a ceramic fiber structure, which comprises restoring ceramic fibers by heating the adhesive to a temperature higher than the softening temperature of the adhesive. 2 The softening temperature of the organic adhesive is 100 to 350°C.
A method for forming a ceramic fiber structure according to claim 1, which falls within the scope of claim 1. 3. The method of forming a ceramic fiber structure according to claim 1, wherein the organic adhesive is contained in an amount of 2 to 15 parts by weight per 100 parts by weight of the ceramic fibers and is uniformly attached to the fibers.