JPS63112478A - Manufacture of heat resistant inorganic fiber formed body - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a heat-resistant inorganic material that can be used as a furnace lining, seed plate, tray, etc. in the firing of ceramics, glass, various metal oxides, etc. The present invention relates to a method for producing a heat-resistant inorganic spa molded body that is lightweight, has high strength, and has excellent thermal shock resistance, and can be used as a molded body mainly composed of 1aftlk, a burner plate, and a catalyst carrier for exhaust gas purification.

[Conventional technology]

Heat-resistant inorganic material m! Molded bodies mainly composed of i are used in various industrial fields because they are lightweight (porous) and have excellent thermal shock resistance. Particularly recently, by combining inorganic substances with the heat-resistant A-type fibers, it has become possible to obtain molded products with higher density and higher strength than before. It is used for linings for firing machine parts, n-plates, shallow pots (hereinafter referred to as trays), etc., and it is also used as a catalyst carrier by taking advantage of its porosity.

(Problems to be Solved by the Invention) As mentioned above, molded bodies mainly made of heat-resistant Aga fibers are molded into various shapes and used for various purposes, but the conventional manufacturing method A widely used method has been to disperse and mix a large amount of heat-resistant inorganic material and additives such as inorganic substances in water, coagulate the mixture, and then vacuum-suction mold the mixture into a mold. With this method, the compact with a low bulk density can be molded and used, but it is particularly difficult to use for various firing jigs and catalyst carriers such as shelves, floorboards, trays, and saggers for firing electronic functional parts. A material with high density and high strength is required and cannot be molded using conventional manufacturing methods, so it is molded into a flat plate, pressed, and then processed into various shapes. The fibers can be kneaded and then molded, or even
A method of mixing various substances while suspended in the air has been considered.

For example, #thermal inorganic particles and inorganic binders (e.g. clay, silica sol, alumina sol, etc.) are made into a slurry of a large amount of wood, vacuum-suctioned into a flat plate, pressed, dried, and then cut into a predetermined shape. The problem is that because the males are stacked in the thickness direction, some parts of the molded body become particularly weak depending on the cutting direction. Specifically, as shown in the schematic diagram of FIG. 1, since there was no mutual strength between the laminated surfaces, there was insufficient strength in the area indicated by the arrow in the diagram, and defects often occurred. In addition, as shown in the figure, products with a deep bottom shape have the problem of low raw material yield and expensive products, making them unsuitable for mass production.

In addition, the use of a flocculant caused the inorganic binder to aggregate and disperse, resulting in low strength.

In addition, the method of pressing granular raw materials, which is often used for ceramic molding, is difficult because the granules, which have heat-resistant inorganic fibers as their core, are not destroyed by pressing, and if they are destroyed, the density cannot be reduced. This results in a structure in which M&male aggregates are continuously connected, resulting in a molded body with no strength at all between the fiber aggregate particles, and as shown in Figure 2, there is a problem in which defects often occur in the engineering and engineering parts due to lack of strength. It struck me.

In addition, a method of obtaining a heat-resistant inorganic female molded body by heat kneading molding using solid wax as a molding aid described in JP-A No. 61-16:117:1 discloses that the viscosity necessary for kneading is reduced with wax. It is difficult to compensate for it and it is enough M
There are problems in that only a molded body having a structure in which A fibers are not dispersed can be obtained, and that dewaxing costs are high and the molded body is expensive.

Furthermore, the method proposed in JP-A-59-18476:1, in which a kneaded mixture of ultra-high temperature ceramic fibers and clay is molded by spraying to obtain a molded body, causes the fibers to become too short, reducing the density of the molded body. In addition, there were problems such as the green density of the molded body being lower than that obtained by means such as press molding, and the strength of the molded body after firing could not be sufficiently improved.

On the other hand, as proposed in Japanese Patent Application Laid-Open No. 58-190855,
A molded product formed by a method of obtaining a porous ceramic molded product by firing a polyurethane foam mixed with ceramic raw materials and removing the polyurethane basically does not contain any fibrous material and has fine pores. Because a molded body cannot be obtained, fiber, 1! There was a problem that the strength was inferior compared to those containing high quality materials.

As described above, conventional methods for producing heat-resistant inorganic fiber molded articles have various problems, and structural defects have appeared due to these problems.

The present invention solves these problems and provides a new method for producing a heat-resistant heat+jJt quality m male molded body, which has never been seen before, and in which heat-resistant By providing a molded body having a structure in which inorganic fibers are uniformly dispersed, heat-resistant inorganic female molded bodies of various shapes that are high in strength, lightweight, and easy to mass-produce are provided, and are suitable for firing the machine parts. The purpose of the present invention is to contribute to energy saving and improve workability of the catalyst, and to contribute to improving the quality and reducing costs of the catalyst carrier.

Means for Solving Problem C) That is, the present invention is characterized by comprising the following steps (a) to (d).
The present invention relates to a method for producing a heat-resistant v1-quality m-fiber molded article, and employs the following means to achieve the above object.

(a) Heat-resistant inorganic rim! For 100 parts by weight of a blended composition consisting of 20-50% by weight of I and 40-800-80% by weight of a refractory powder and 5-30% by weight of a binder, 30-150 parts by weight of wood and, if necessary, organic molding. The solid content of the auxiliary agent is 0.
(Is) Degassing the kneaded product; (c) Putting the degassed product into a porous mold and press-molding it at room temperature. (d) 800 to 1600'C after drying the press molded body;
The process of firing at a temperature range of

(Function) Molded bodies made mainly of heat-resistant inorganic fibers are used after being processed into various shapes as parts of industrial furnaces because they are lightweight and have excellent thermal shock resistance. However, most of them have been manufactured by vacuum suction molding a slurry in which the fibers are dispersed in a large amount of water. With this method, the fibers are stacked perpendicular to the direction of suction, resulting in parts with weak strength, and it is difficult to process irregularly shaped items such as Fukabayashi, and the raw material yield is low, making it difficult to mass-produce. was not suitable.

The present invention was disclosed for the first time through the development of a new method for molding a molded article made mainly of heat-resistant inorganic fibers using a press method most suitable for mass production, and basically consists of the following four items. It consists of

The first is to disperse heat-resistant inorganic fibers in a mixed composition of refractory powder and an inorganic binder. In order to mix the ta male material into the powder material, the uA fibrous ball is cut into short lengths, but the space where the tag material is made can be filled with a substance that will volatilize during drying or firing. Although it is necessary, the former method increases the density of the molded body and is not suitable for the purpose of the present invention, so the latter method becomes a necessary condition. here,
The filling is preferably water or the cheapest. However, in order to sufficiently defibrate fibrous materials, it is effective to place a highly viscous substance between the layers and utilize its shearing force, and this viscosity can be reduced using fire-resistant powder or inorganic binder. If not compensated, organic forming aids are added to develop viscosity. Therefore, the mixture itself becomes a flexible raw material containing a large amount of water, and is completely different from a press raw material, that is, a granular raw material, which is usually molded using a spray dryer. As a result, a uniform molded body can be obtained without applying much pressure. Specifically, heat-resistant inorganic materials! , 1!20
30 to 150 parts by weight of water and, if necessary, to 2 parts by weight of 100 parts of a blended composition consisting of ~50% by weight, 40 to 80% by weight of refractory powder, and 5 to 30% by weight of an inorganic binder. It is preferable to add and knead an organic molding aid in a solid content of 0.5 to 10 parts. Preferably, the heat-resistant inorganic fiber is one or more selected from aluminosilicate mrts, crystalline alumina iaMi, crystalline mullite fiber, silica fiber, zirconia m, *,
The blending composition is preferably 20 to 50% by weight. If it is less than 20% by weight, the density of the molded product becomes too high, and if it exceeds 50% by weight, the strength becomes low, which is not preferable. The refractory powder is preferably one or more selected from alumina sol magnesia, titania, and chromia, and specifically, alumina, mullite, kaolinite, wood tablet clay, and chromia. Clay, shisomanite, steatite, fustellite, talc, zirconia, magnesia, spinel,
Titania, chromia, etc. are preferred, and the blending composition is 40-8
It is preferable to set it to 0% by weight. , 10? If it is less than li%, the strength will be insufficient, and if it exceeds 80%, the density will be undesirably high. The inorganic binder is silica/soda based.

Preferably, it is selected from calcium borate-based, silica-based frit, alumina sol, and silica sol, for example,
Suitable combinations include feldspar, mica powder, phosphoric acid, glass powder, silica sol, alumina sol, and silica sol! lrJ, is 5-3
It is better to set it to 0% by weight. If it is less than 5% by weight, the strength of the compact will be low, and if it exceeds 30% by weight, sintering will progress and it will become too heavy, which is not preferable. For 100 parts of the above blended composition.

A raw material for molding is prepared by adding 30 to 150 parts by weight of water and, if necessary, an organic molding aid in a solid content of 0.5 to 10 parts by weight. If the amount of water is less than 30 parts by weight, the fibers will not be sufficiently demagnetized and pill-like fibers will remain, and if it exceeds 150 parts by weight, the kneaded material will become soft and lose shape after molding, which is not preferable. Further, the organic molding aids include methylcellulose, carboxymethylcellulose, and vinyl acetate,
If the amount of this molding aid, which is preferably one or more selected from polyacrylic resin and water-dispersed wax emulsion, is less than 0.5 parts by weight, the dry strength of the molded product will decrease. If it exceeds 10 parts by weight, the cost will be high and it is not suitable. The above blending amount 1> is kneaded with a commercially available kneader, but in order to disperse the fibers without cutting them into short pieces, it is best to knead with a blade mixer commonly used for food products. Ball mills and Ni-Goo are not effective because the fibers break and the density of the compact increases.

The second step is to deaerate the kneaded material. Especially m! I
If it is not deaerated, cracks are likely to occur in areas where there is no connection between fibers, which is undesirable as it leads to a decrease in the quality of the molded product. Degassing is possible in a batch-type vacuum container, but from the viewpoint of productivity it is best done in a screw equipped with a vacuum evacuation system.

The third method is to put the degassed material into a porous mold and press it at room temperature. Since the degassed material contains a large amount of water, it is highly adhesive and cannot be released from the mold at all with a general mold. By making the mold surface uneven, it becomes possible to release the mold a little, but it is not durable and cannot be used. For molding raw materials with high moisture content, potter's wheel molding, mud casting, etc. are commonly used, but molding of raw materials containing materials with greatly different specific gravity, or molding of objects that are not circular, cannot be used. The gypsum mold used in this is a material well suited for molding raw materials with a high moisture content. However, the plaster mold often cracks when it absorbs water and collapses after drying, resulting in very low durability.

The present inventors conducted research on molds with good mold release and high durability, and newly discovered that a material with continuous pores is most suitable for the kneaded raw material of the present invention. Specifically, continuous pores are formed by intertwining fibrous materials and filled with organic resin or inorganic powder to provide the necessary strength and elasticity to the mold. Molding using the above-mentioned porous mold can greatly contribute to cost reduction because the cross-wire-degassed raw material has appropriate viscosity, so it stretches well and can be pressed at room temperature.

Fourth, after drying the press molded body, the temperature is 800 to 1600°C.
It is to be fired at a temperature range of . The purpose of firing is to incinerate the organic resin and improve the strength of the molded product.

That is, the heat-resistant inorganic material ta! A high-strength structure can be obtained by sufficiently sintering lI, refractory powder, and inorganic binder. Moreover, the press-formed product can be used without agglomerating the inorganic binder unlike in the conventional paper-making method, so the binder effect is uniformly exhibited and the
A significantly superior strength of 0 kgf/cm'' can be obtained.

The heat-resistant inorganic fiber molded article of the present invention molded as described above has a temperature of 0.6 to 2. It is preferable that the bulk density is f1g/c. If it is less than 0.6 g/cm'', sufficient strength will not be obtained, and if it exceeds 2.0 g/cm', it will become too heavy, resulting in an increased amount of heat storage or poor thermal shock resistance, which is not preferable.

Examples of the present invention will be described below.

〔Example〕

Example 1 A layer containing non-fibrous matter was reduced to 3wL by classification in water.
% NirrJl GoL/TaAl 20 = 50wt
%, 5in2SOvt% aluminosilicate fiber fi
Alumina powder 1100 with 600g and average particle size 4.5gm
Blend 300 g of clay and 150 g of calcined diatomaceous powder into a multipurpose mixer, add 950 g of water and organic molding aids (wax, polyacrylamine acetate) 30
After adding 0g, knead for 5 minutes, then degas in a vacuum kneading machine, then put into a porous mold and mix at 20kgf/crn'.
Press with pressure of 200x 200x 8o I
I+ fiber (inner size 180x t80x 6011■)
A deep forest-shaped molded product was manufactured. After drying at 1450°C6
Heat-resistant inorganic material with a density of 1.1 g/crn' after firing for hours m! ! A molded body was obtained.

Example 2 300 g of crystalline alumina fiber, 300 g of alumina powder with an average particle size of 4.54 m, and 100 g of montmorillonite were blended and placed in a 3,000-ton mixer, and 1000 g of vinyl acetate resin water-dispersed emulsion with a solid content of 5 wt% was added. After that, the mixture was kneaded for 7 minutes, and then after vacuum degassing, it was placed in a porous plaster mold and pressed at a pressure of 15 kgf/crn' to produce a molded article similar to Example 1. After drying, it was baked at 1600℃ for 3 hours to give a strength of 2DOkgf/c and a density of 1.0.
A molded article with a weight of 1.5 g/fiber was obtained.

(Effects of the Invention) As described above, according to the present invention, a high-strength, lightweight heat-resistant inorganic fiber molded article can be easily sized, and irregularly shaped molded articles can be manufactured at low cost.

[Brief explanation of the drawing]

Figure 1 shows conventional heat-resistant inorganic fiber! A cross-sectional view of the lk molded body,
FIG. 2 is a cross-sectional view of a heat-resistant inorganic fiber molded article formed from a granular raw material, and the arrows in both figures indicate areas of weak strength.

Claims (6)

[Claims] (1) A method for producing a heat-resistant inorganic fiber molded article having a bulk density of 0.6 to 2.0 g/cm^3, comprising the following steps (a) to (d). (a) 30 to 150 parts by weight of water per 100 parts by weight of a blended composition consisting of 20 to 50% by weight of heat-resistant inorganic fibers, 40 to 80% by weight of fire-resistant powder, and 5 to 30% by weight of an inorganic binder. and, if necessary, organic molding aids at a solid content of 0.5
(b) degassing the kneaded product; (c) putting the degassed product into a porous mold and pressing and molding at room temperature. (d) a step of baking the press-formed product at a temperature range of 800 to 1600°C after drying; (2) The manufacturing method according to claim 1, wherein the kneading is performed using a universal mixer. (3) A patent claim characterized in that the heat-resistant inorganic fiber is one or more selected from aluminosilicate fiber, crystalline alumina fiber, crystalline mullite fiber, silica fiber, and zirconia fiber. The manufacturing method according to the ranges 1 and 2. (4) The refractory powder is one or more selected from alumina, alumina/silica, zirconia, magnesia, titania, and chromia. The manufacturing method according to ranges 1 to 3. (5) Claims characterized in that the inorganic binder is one or more selected from clay, glass frit, sodium silicate, calcium borate, silica, alumina sol, and silica sol. The manufacturing method according to items 1 to 4. (6) A patent claim characterized in that the organic molding aid is one or more selected from methylcellulose, carboxymethylcellulose, vinyl acetate, polyacrylic resin, and water-dispersed wax emulsion. The manufacturing method according to the ranges 1 to 5.