JPH0796469B2 - Heat resistant inorganic fiber molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a heat-resistant inorganic material that can be used as a lining of a furnace, a shelf plate, a tray, etc. in the firing of ceramics, glass, various metal oxides and the like. The present invention relates to a light-weight, high-strength, heat-resistant inorganic fiber molding which can be used as a fiber-based molding, a burner plate, and an exhaust gas-purifying catalyst carrier, and which has excellent thermal shock resistance.

[Conventional technology]

Molded products mainly composed of heat-resistant inorganic fibers are used in various industrial fields because they are lightweight (porous) and have excellent thermal shock resistance. Particularly recently, by compounding the heat-resistant inorganic fiber with an inorganic substance, it has become possible to obtain a molded body having a higher density and higher strength than ever before. For example, electronic functional parts such as capacitors, sensors and IC substrates. Liners, shelves, and shallow pots for baking (hereinafter called trays)
It is also used as a catalyst carrier due to its porosity.

[Problems to be solved by the invention]

As described above, the molded product mainly composed of the heat-resistant inorganic fiber is molded into various shapes and used for various purposes, but the conventional manufacturing method is to use the heat-resistant inorganic fiber and the additive such as the inorganic substance. A method of dispersing and mixing in a large amount of water, aggregating, and then vacuum suction molding in a molding die has been widely used.
With this method, molded products with low bulk density can be molded, but in particular, shelf boards, floor boards, trays, etc. for firing electronic functional parts
As for the use of various baking jigs such as saggers and catalyst supports, high density and high strength materials are required, which cannot be formed by conventional manufacturing methods. Molding, kneading the heat-resistant inorganic fiber in the thermoplastic resin, thermosetting resin, or further,
A method of mixing various substances while suspended in the air has been considered.

For example, heat-resistant inorganic fibers and an inorganic binder (for example, clay, silica sol, alumina sol, etc.) with a large amount of water are vacuum-suctioned into a slurry form, pressed into a flat plate form, pressed, dried, and then cut into a predetermined shape. Since the layers are laminated in the thickness direction, there is a problem that a part of the molded body becomes particularly weak depending on the cutting direction. Specifically, as shown in the schematic diagram of FIG. 1, since there is no mutual strength between the laminated surfaces, the raw material yield is low and the product is expensive for deep-shaped products at the portion indicated by the arrow. Therefore, it was not suitable for mass production. Moreover, the strength was low because the inorganic binder was aggregated and dispersed by using the coagulant.

In addition, the method of pressing a granular raw material that is often used for forming ceramics is such that the granules having the heat-resistant inorganic fiber as the core are not destroyed by the pressing, and if the granules are destroyed, the density cannot be reduced and the granular There is a problem that the fiber aggregate has a structure in which the fiber aggregates are continuously connected to each other, resulting in a molded body having no strength between the fiber aggregate particles, and the edge portion is often damaged due to insufficient strength as shown in FIG.

Further, a method of obtaining a heat-resistant inorganic fiber molded body by heat kneading and molding using a solid wax as a molding aid as disclosed in JP-A-61-163173 is such that the viscosity necessary for kneading is compensated by the wax. However, there are problems that it is difficult to obtain a molded product and only a molded product having a structure in which the fibers are not sufficiently dispersed can be obtained, and that the dewaxing cost is high and the molded product is expensive.

Further, as proposed in JP-A-59-184763, a method of obtaining a molded product by molding a kneaded product of ceramic fiber for ultrahigh temperature and clay by spraying is to shorten the density of the molded product because the fiber becomes too short. However, there is a problem in that the green density of the molded body is lower than that of the means such as press molding, and the strength of the molded body after firing cannot be sufficiently improved.

On the other hand, as proposed in JP-A-58-190855, a molded body formed by a method of firing a polyurethane foam mixed with a ceramic raw material to remove polyurethane to obtain a porous ceramic molded article is basically Since it does not contain a fibrous material and a molded product having fine pores cannot be obtained, there is a problem that the strength is inferior as compared with a product containing a fibrous material.

As described above, the conventional heat-resistant inorganic fiber molded body has a structural problem due to the manufacturing method, and the capacitor, the sensor, the IC substrate, the shelf for firing electronic functional components such as ferrite, and the tray are particularly loaded. It was used only for the part that does not take most of. Also, a deep bowl-shaped object such as a bowl has not been used because of its expensive shape.

The present invention solves these problems, by providing a molded body having a structure in which the heat-resistant inorganic fibers are uniformly dispersed in a mixed composition of a refractory powder and an inorganic binder, by high strength We provide heat-resistant inorganic fiber moldings of various shapes that are lightweight and easy to mass-produce, contributing to energy saving and improvement of workability of the jig for firing functional parts, contributing to quality improvement and cost reduction of the catalyst carrier. The purpose is to do.

[Means for solving problems]

The present invention, in order to achieve the above object, a heat-resistant inorganic fiber
20-50% by weight, refractory powder 40-80% by weight, and inorganic binder 5
-30% by weight, the heat-resistant inorganic fibers in the composition composed of the refractory powder and the inorganic binder in a defibrated state without being oriented in a particular direction,
Has a uniformly dispersed structure and a bulk density of 0.6-1.5 g / cm
^The present invention provides a heat-resistant inorganic fiber molded body characterized by having a bending strength of 3 and having a bending strength of 150 to 300 kgf / cm ² .

[Action]

The heat-resistant inorganic fiber molded body of the present invention has a large number of continuous pores in the molded body because the heat-resistant inorganic fiber is the main component, and its weight reduction and thermal shock resistance are improved, and the heat conduction at room temperature is improved. The rate is as low as 0.15 to 0.3 Kcal / mhr ° C, which contributes to a reduction in the amount of electricity stored during firing and a reduction in firing time.
Energy costs can be reduced. Specifically, it is preferable that the density is 0.6 to 1.5 g / cm ³ , and 0.6 g / cm ³
If it is less than cm ³ , the strength is insufficient, and if it exceeds 1.5 g / cm ³ , the amount of stored electricity cannot be lowered and the thermal shock resistance becomes inferior, which is not preferable. A density of 1.0 to 1.3 g / cm ³ is particularly suitable.

Further, the heat-resistant inorganic fiber molded body of the present invention is obtained by filling a refractory powder and / or an inorganic binder between the fibers of the heat-resistant inorganic fiber, and sintering the refractory powder and / or the inorganic binder. As a result, it is possible to obtain a molded body that is a stronger structure than a conventional molded body containing a fibrous material as a main component. In particular, in the present invention, the heat-resistant inorganic fibers are dispersed in the composition consisting of the refractory powder and the inorganic binder uniformly without being oriented in a specific direction in a state where most of them are defibrated. Since the molded body has the above structure, it is possible to obtain a significantly improved strength as compared with the conventional product.

That is, a molded body obtained by a method of vacuum suctioning a heat-resistant inorganic fiber and an inorganic binder with a large amount of water that has been often performed conventionally is that the fibers are laminated in the suction direction, or Based on the reason that the molded body itself is composed of an aggregate of large-particle inorganic binders because it aggregates in order to increase the yield of the inorganic binder, there is a directionality in the strength of the molded body, and high strength On the other hand, in the molded article of the present invention, which was not obtained, the fibers are uniformly dispersed, and since the inorganic binder can be used without aggregating, its function can be sufficiently exhibited, It is possible to obtain a strength that does not seem to be the formed body mainly. For example, the molded body obtained by the conventional method but was only bending strength 40~120kgf / cm ^2, according to the present invention, it becomes possible to obtain a strength of 150~300kgf / cm ^2, It can now be used as a jig for firing heavy electronic components such as alumina and ferrite, which were difficult to use in the past.

In order to disperse the heat resistant fiber in the mixed composition of the refractory powder and the inorganic binder, it is preferable to use a kneaded product for food products such as bread and chocolate. In a model kneader or hole mill, the fibers are not sufficiently disentangled, which is not preferable.

The heat-resistant inorganic fiber, aluminosilicate fiber, crystalline alumina fiber, crystalline mullite fiber, silica fiber,
It is preferable that any one kind or two or more kinds selected from the zirconia fibers is used. In particular, aluminosilicate fibers and silica fibers having high fiber strength are preferable because they can be mixed and molded as long fibers as they are, and the density of the molded body is lowered to reduce the amount of stored electricity. Also, crystalline alumina fiber, crystalline mullite fiber, zirconia fiber, etc. have high heat resistance temperature and excellent touch resistance, so they are suitable as a jig for firing under more severe conditions such as alumina, ferrite, and piezoelectric elements. Is.

The refractory powder, alumina, alumina-silica,
It is preferable that one or more selected from zirconia, magnesia, titania and chromia. Specifically, alumina, mullite, kaolinite, kibushi clay, frog eye clay, sillimanite, steatite, forsterite, talc, zirconia, magnesia, spinel, titania and the like are preferable.

Furthermore, the inorganic binder of the present invention is a silica / soda-based, calcium borate-based, silica-based frit, alumina sol,
It is preferably selected from silica sols, for example, feldspar, mica powder, boric acid, glass powder, silica stone, alumina sol, silica sol and the like.

The heat-resistant inorganic fiber molding of the present invention is the heat-resistant inorganic material
20 to 50% by weight, 40 to 80% by weight of the refractory powder, and 5 to 30% by weight of the inorganic binder are added as needed with an organic molding aid, and after kneading and degassing, porous molding is performed. It is manufactured by putting it in a mold and pressing it. Here, the heat-resistant inorganic fiber is 20
When it is less than 50% by weight, the density becomes too high and the thermal shock resistance becomes poor, which is not preferable, and when it exceeds 50% by weight, sufficient strength cannot be obtained, which is not preferable. Further, if the refractory powder is less than 40% by weight, the strength is insufficient, and if it exceeds 80% by weight, the density becomes high, which is not preferable. Further, if the amount of the inorganic binder is less than 5% by weight, the strength of the molded body becomes a low value, and if it exceeds 30% by weight, it becomes too heavy, which is not preferable.

Hereinafter, examples of the present invention will be described together with comparative examples.

〔Example〕

Example 1 As heat resistant inorganic fibers, Al ₂ O ₃ 50 wt%, SiO ₂ whose content of non-fibrous material was controlled to 3 wt% by classification in water, SiO ₂
600 g of 50 wt% aluminosilicate fiber, 1100 g of alumina powder with a mean particle size of 4.5 μm as fire resistant powder and Kibushi clay
300 g and 150 g of calcined diatomaceous earth as an inorganic binder were mixed and put in a kneader, 950 g of water and 300 g of an organic molding aid (wax, polyacrylamine acetate) were added, and then kneaded for 5 minutes. After degassing the kneaded product, put it in a plaster mold for 10-30
Pressed with a pressure of kgf / cm ² to 200 × 200 × 80Hmm (inside dimension 180
A deep pot-shaped molded product of × 180 × 60Hmm) was produced. After drying 14
It was fired at 50 ° C. for 6 hours to obtain an example of the present invention.

Comparative Example 1 A composition similar to that of Example 1 was dispersed in 30 water to prepare a slurry, and 500 ml of polyacrylamide, 10 wt% and 600 ml of an aqueous solution of vanadium sulfide were added and aggregated to form a vacuum suction molding into a 300 × 300 mm flat plate. did. After drying, it was cut to the same shape and density as in Example 1, and subsequently fired at 1450 ° C. for 6 hours to obtain a comparative example of the present invention.

Comparative Example 2 The same slurry as in Comparative Example 1 was aggregated and then vacuum suction molded into a 200 × 200 × 80H deep pot-shaped mold. When pressed while being attached to the mold to set the density after molding, cracks were formed in the corners, and a molded product having a predetermined density could not be obtained.

Comparative Example 3 600 g of an aluminosilicate fiber having a fiber length of 1 to 2 mm and a non-fibrous substance content controlled to 3 wt%, 1100 g of alumina powder and 300 g of kibushi clay and 150 g of fired diatomaceous earth were dispersed in a PVA aqueous solution, and then a spray dryer was used. Was molded into granules. The granules were placed in a plaster mold similar to that used in Example 1 and pressed to produce a deep pot-shaped molded product, which was dried and then baked at 1450 ° C. for 6 hours to give a comparative example of the present invention. When the granules were crushed, the density became too high, and when the granule shape remained, the strength was low and it was poor.

Table 1 shows the compact density and the bending strength in each direction of Examples and Comparative Examples of the present invention.

As can be seen from this table, according to the examples of the present invention, it is possible to manufacture a high-strength molded product without variations in strength. Here, the bending strength is the size of the test piece 10 mm × 50 mm × 5 mm, the span length 3
It was measured with an Shimadzu autograph under the conditions of 0 mm and a bending speed of 10 mm / min.

〔The invention's effect〕

 As described above, according to the present invention, the following effects are exhibited.

(1) High-strength, heat-resistant inorganic fiber moldings of various shapes can be formed, and heavy ceramics can be fired.

(2) Heat resistant inorganic fiber moldings of various shapes can be mass-produced at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a conventional heat-resistant inorganic fiber molding,
The figure is a cross-sectional view of a heat-resistant inorganic fiber molded body formed from a granular raw material, and the arrows in both of these figures represent weak portions.

Claims (4)

[Claims] 1. A heat-resistant inorganic fiber 20 to 50% by weight, a refractory powder 40 to 80% by weight, and an inorganic binder 5 to 30% by weight,
Most of the heat-resistant inorganic fibers are in a defibrated state, in the composition comprising the refractory powder and the inorganic binder, without being oriented in a specific direction, a uniformly dispersed structure. A heat-resistant inorganic fiber molded article having a bulk density of 0.6 to 2.0 g / cm ³ and a bending strength of 150 to 300 kgf / cm ² . 2. The heat resistant inorganic fibers are aluminosilicate fibers, crystalline alumina fibers, crystalline mullite fibers,
Any one selected from silica fiber and zirconia fiber
The heat-resistant inorganic fiber molded article according to claim 1, characterized in that it is one kind or two or more kinds. 3. The refractory powder is one or more selected from alumina, alumina-silica, zirconia, magnesia, titania, and chromia. The heat-resistant inorganic fiber molded product according to claim 1 or 2. 4. The inorganic binder is any one or two or more selected from clay, glass frit, sodium silicate, calcium borate, silica stone, alumina sol and silica sol. The heat-resistant inorganic fiber molded article according to any one of claims 1 to 3.