JPH0559866B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an amorphous heat-insulating refractory material composition whose basic composition is ceramic fiber, and a heat-insulating refractory molded article formed from the composition. [Prior art] When the amount of water is such that the bulk fiber of inorganic fiber is wet (50% of water is used for the bulk fiber)
(Below) It may be said that the two are evenly mixed, but if the amount of water is slightly larger than this, the water separates or tends to separate, and a homogeneous composition is not formed. Therefore, it is necessary to add a thickener to the water in order to give it appropriate plasticity and fluidity.
Acrylic polymers and polyethylene oxide are used for this purpose. These dissolve in water and have a large thickening effect with a small amount, and disperse fibers and coexisting fine powders in water (solution) to form a nearly homogeneous composition, but these have too thickening effect and dispersion. The effect is large, and when attempting to separate only water (solution) from the composition later, the over-dehydration properties are extremely poor, and even if the amount added is reduced, this property cannot be improved. [Problems to be Solved by the Invention] The present invention has a property that, like plastic refractories, it deforms freely under relatively large stress, but is difficult to deform under small stress such as its own weight, and On the one hand, it is an inorganic fibrous heat-insulating fire-resistant composition (first composition) capable of constructing a joint-free fire-resistant thermal wall, and on the other hand, it is a composition containing a large amount of water in the form of slurry. The composition has the property of easily filling small gaps due to its excellent fluidity, and when all or part of the walls constituting the gap is made of a water-absorbing or porous material, water can be easily dehydrated from the composition. An inorganic fibrous refractory material composition (second composition) having properties that should be reduced to the above-mentioned first composition with a lower water content, and a combination of the first composition and the second composition. In between there are many and compositions exhibiting intermediate properties. Furthermore, the desired or required shape can be easily formed by press molding in the case of the first composition, vacuum molding in the case of the second composition, pouring into porous molds, gaps between ceramic fiber walls, etc. It has a wide composition range that allows molded bodies with a wide range of physical properties (bulk specific gravity, air permeability, thermal conductivity, etc.) to be produced by drying and firing. The composition according to the present invention uses water as a medium, and even when it contains a large amount of water, it is very easy to dehydrate even though it is a solid slurry. Most of it remains in the dehydrated composition, and only a small proportion is lost in the wastewater. [Means for Solving the Problems] The present inventors have selected a thickening material that has a moderate thickening effect and has a small electrical polarity when dissolved in water. These include methylcellulose, starch,
Examples include PVA. These are soluble in water, have a moderate thickening effect, and do not show much resistance during subsequent processing. One of the basic materials of the present invention is bulk fiber, and at the same time, the addition of fine refractory powder can have an extremely excellent effect depending on the high temperature usage conditions of the composition and molded article. For example, its addition can improve fire resistance, corrosion resistance, thermal conductivity, and strength. Fine powders of ordinary refractory materials such as alumina, mullite, clay, zircon, silica, zirconia, silicon nitride, and silicon carbide with a particle size of about 200 μm or less can be easily mixed with fibers. The amount should be no more than 10 times that of bulk fiber. (See Japanese Patent Publication No. 57-35087.) Next, what is required for the composition of the present invention is a binder that is effective at high temperatures. Under high-temperature usage conditions, ceramic fibers and fine powders must be bonded together to maintain a certain shape and have the necessary strength to form a heat insulating or fireproof wall. The binder used for this purpose is colloidal silica or colloidal alumina. These are commonly used as binding materials for ceramic fibers, but colloidal silica or colloidal alumina is aggregated and cross-linked into fibers or fine powder, so that colloidal silica and colloidal alumina are wastefully discharged into wastewater. It is quite difficult to prevent this from happening. In the present invention, an emulsion of higher fatty acids is used as the aggregating material. Particularly good are emulsions of stearic acid, for example, in which colloidal silica is agglomerated in a methylcellulose solution to form a large secondary emulsion, which engages and crosslinks ceramic fiber fibers or fine powders. form. Moreover, the composition is a homogeneous plastic material or slurry-like material, and when dehydration is performed later, most of the water (solution) can be easily separated while maintaining the crosslinked structure. Conventionally, when colloidal silica is used as a binder for ceramic fibers, when the mixed composition is dried, a phenomenon (referred to as migration) occurs in which the colloidal silica moves to the outer surface of the composition as water evaporates. The composition of the present invention does not cause migration of colloidal silica and provides a dried product with uniform hardness. Next, although not essential to the present invention, the first requirement that makes the present invention more effective is the addition of glycerin as a deformation prevention material. When the present composition is press-molded to form a thin plate and this is dried, it is necessary to keep the thin plate flat, but this is actually very difficult. The present inventor has discovered that by adding glycerin to the composition of the present invention, deformation during drying can be effectively prevented. However, the reason for this remains unclear. Next, when the present composition is dehydrated, the effect of wax emulsion in imparting fluidity to a certain dehydrated composition will be discussed. Wax emulsion binds to crosslinked large particles formed from higher fatty acid emulsion and colloidal silica, and during dehydration, it effectively drains the water (solution) between the large particles and improves the mutual sliding between the large particles. It is believed that this improves the moldability of the partially dehydrated composition. Without the addition of wax emulsion, fluidity is poor and moldability is poor. Addition of wax emulsion solves these problems, but at the same press pressure, a molded product with a smaller bulk specific gravity is obtained than one without the addition of wax emulsion. Next, conditions necessary for the configuration of the present invention will be explained. (a) The amount of water added is based on 100 parts of bulk fiber.
More than 50 copies. If the amount of water added is less than 50 parts, the bulk fiber will be merely damp or wet and will not be able to provide adequate plasticity.
When the amount of water is large, there is no problem and the composition can be dehydrated to an appropriate amount. (b) Methylcellulose, starch, which is a thickening agent;
PVA may be added in an amount of 0.5 to 10 parts per 100 parts of water, and may be one or a combination of two or more thickeners. The amount of thickener naturally has upper and lower effective limits, which have been determined experimentally. If the thickener is less than 0.5 part, it will not be possible to impart appropriate viscosity to the water (solution), and as a result, the bulk fiber and coexisting fine refractory powder will not be dispersed appropriately. More than 10 parts imparts excessive viscosity to the water (solution), so that it is difficult to later dehydrate the water (solution) from the composition. (c) Fine powder of refractory material may be added for the purpose of improving the properties of the composition during use at high temperatures.
The amount added is per 100 parts of bulk fiber.
Less than 1000 copies. The types of refractory fine powder include commonly used alumina, mullite, clay, silica, zircon, zirconia, silicon nitride, silicon carbide, etc., and the particle size is preferably smaller than 200μ. If 1000 parts or more of the refractory fine powder is added, the proportion of the refractory fine powders agglomerating together will increase, making it difficult to obtain a uniform mixture with the bulk fiber. When the amount is 1000 parts or less, a uniform mixed state can be obtained in a state where it is uniformly adhered to the surface of the bulk fiber. (d) To combine fibers and fine particles at high temperatures to form a heat-insulating fireproof wall, etc., and to combine with other additives to give the composition appropriate plasticity and fluidity as well as excellent dehydration properties. Colloidal silica or colloidal alumina as a binder for
If a 40% suspension is used, the amount is 5 to 50 parts per 100 parts of the bulk fiber and refractory fine powder. Naturally, this addition amount also has upper and lower limits. If the amount of binder added is less than 5 parts, the strength of the composition after drying will be insufficient. If the amount is 50 parts or more, the dehydration time will be longer when dehydrating the composition. (e) The agglomerate for combining with the colloidal silica or colloidal alumina to give the composition suitable plasticity, fluidity and good dehydration properties is an emulsion of higher fatty acids. Among these, stearic acid emulsion is easily available and convenient. The effect appears when the amount added is 0.1 part or more per 100 parts of colloidal silica or colloidal alumina 40% suspension. There is no effect below 0.1 part. (f) Although not essential to the present invention, there are two requirements that can be made more effective by addition, the first of which is glycerin. Glycerin is added to prevent the occurrence of "warpage" when the composition is dried after dehydration, especially when drying a thin plate.The amount of glycerin added is 3 parts or less per 100 parts of water.
If more than 3 parts are added, the time required for drying the composition will be too long. (g) The second requirement is a wax emulsion.
The wax emulsion has the effect of imparting fluidity to the dehydrated product during or after the dehydration of the present composition, and improves the moldability during molding. The amount added is colloidal silica or colloidal alumina 40
10 parts or less per 100 parts of suspension. Even if 10 parts or more is added, the effect remains the same. In addition, using this composition, dehydration and
A molded article can be produced by molding, drying or firing. [Example] An example of the present invention will be described. Experiment Nos. A, B, C, D, and H in Table 1 are those of the present invention, and Experiment Nos. F, G, and H are reference examples. (In addition,
(The numbers indicate the proportions and parts by weight.) A and B are compositions with medium moisture content and flexibility, and are suitable for troweling, manual construction, or press dehydration molding. It is a thing. C and D are slurry-like compositions for pouring with a high water content, and are suitable for vacuum forming and casting methods. E is a hard composition with a low water content, similar to plastic refractories, and can be press-molded. In reference example F, colloidal silica coagulation was insufficient due to insufficient amount of higher fatty acid emulsion added, and migration of colloidal silica occurred when drying the composition, resulting in hardened surface but soft interior. It became a molded object. In Reference Example G, since the amount of thickener added was insufficient, a homogeneous composition was not formed, and the fibers and the aqueous solution were easily separated. In Reference Example 1, the amount of colloidal silica added was insufficient, so it did not have the effect of binding fibers and fine particles, and these easily separated from the aqueous solution and did not form a homogeneous composition. In the examples A, B, C, D, and E of the present invention, the fibers and the aqueous solution do not separate but combine with the fibers and fine particles to form a homogeneous composition, causing migration. It produces a dry body with uniform hardness.

【table】

[Table] Experiments that do not meet the configuration requirements

Claims (1)

[Claims] 1. Bulk fiber of ceramic fiber
50 parts or more of water per 100 parts, 0.5 to 10 parts of one or more thickeners such as methyl cellulose, starch, PVA, etc. per 100 parts of water, and alumina, mullite, clay, etc. per 100 parts of bulk fiber. 1000 parts or less of one or more types of refractory fine powder such as silica, zircon, zirconia, silicon carbide, silicon nitride, etc. and colloidal silica or colloidal alumina per 100 parts of the bulk fiber and the refractory fine powder. 0.1 part of higher fatty acid emulsion per 100 parts of colloidal alumina or colloidal silica suspension and 100 parts of colloidal alumina or colloidal silica suspension.
If necessary, 3 parts or more of glycerin per 100 parts of the water or/and
and an inorganic fibrous amorphous heat insulating and refractory material composition, characterized in that 10 parts or less of a wax emulsion is added to 100 parts of a suspension of colloidal silica or colloidal alumina. 2 Bulk fiber of ceramic fiber
At least 50 parts of water per 100 parts and 1 or 2 thickeners such as methylcellulose, starch, PVA, etc. per 100 parts of water.
Bulk fiber with 0.5 to 10 parts or more of seeds and 100 parts of bulk fiber and 100 parts or less of one or more fine powders of refractory materials such as alumina, mullite, clay, silica, zircon, zirconia, silicon carbide, silicon nitride, etc. and a suspension containing a solid content equivalent to 5 to 50 parts of a 40% suspension of colloidal silica or colloidal alumina, and a suspension of colloidal alumina or colloidal silica, based on the content of 100 parts of the refractory fine powder. Higher fatty acid emulsion 0.1 per 100 parts of liquid
If necessary, 3 parts or more of glycerin per 100 parts of the water or/and
and an inorganic fibrous heat-insulating and refractory material molded article obtained by dehydrating, molding, drying or firing a composition in which 10 parts or less of a wax emulsion is added to 100 parts of a suspension of colloidal silica or colloidal alumina.