JP2000256921A - Inorganic fiber and refractory heat-insulating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber having high fiber-forming efficiency and low heat-conductivity and provide a refractory heat-insulating material. SOLUTION: The inorganic fiber is composed of 50-75 wt.% silica, 10-49 wt.% titania, 0-30 wt.% alumina and 0.3-7 wt.% one or more oxides of metals selected from iron, nickel, cobalt, copper, zirconium, niobium, zinc and manganese.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic fiber and a refractory heat insulating material, and more particularly to an alumina-silica-titania inorganic fiber and a refractory heat insulating material using the inorganic fiber.

[0002]

2. Description of the Related Art Alumina-silica fibers composed of 40 to 60% by weight of alumina and 60 to 40% by weight of silica have been widely known as inorganic fibers for high temperatures. This inorganic fiber is usually produced by fiberization by a melt spinning method. As a melt spinning method, there is known a blowing method in which a melt is taken out as a small stream after melting an original material, and high-speed air is applied to the small stream to form fibers. There is also known a spinning method in which a rivulet is dropped on a high-speed rotating rotor to form fibers.

[0003] A fiber aggregate that has just been fiberized by the melt spinning method contains shots (particles that did not become fibers) in addition to the fibers. The smaller the content ratio of the shot in the fiber aggregate, the better the fiberization efficiency, and thus the more preferable.

[0004] The fiberization efficiency is greatly affected by the viscosity and surface tension of the melt. If the melt does not have an appropriate viscosity, the fiberization efficiency will be low. And, even if the viscosity is the same, if the surface tension of the melt is large, the fiberization efficiency is reduced.

[0005]

Alumina-silica fibers produced by the melt spinning method are generally made of 62 mesh (pore size 212).
μm) or more.

For use as a heat insulating material, it is preferable that the amount of shots be small. Accordingly, fibers with lower shot volumes are desired.

[0007] Many alumina silica fibers are processed into blankets or molded products and used as fire-resistant heat insulating materials. At this time, if the refractory heat insulating material is excellent in heat insulation, that is, if the thermal conductivity is small, the thickness of the refractory heat insulating material can be reduced. That is, the device can be downsized.

[0008] From this point, there is a demand for a refractory heat insulating material having a small thermal conductivity.

Alumina-silica fibers require a high temperature when melting the raw material, because the melting point of alumina is high. The melt has a large surface tension and a low viscosity. And this viscosity changes greatly with temperature. Due to these characteristics, the alumina silica fiber has low fiberization efficiency.

Further, since the alumina silica fiber has a high thermal conductivity of alumina, the fiber itself has a high thermal conductivity. Therefore, the refractory heat insulating material using such an alumina silica fiber has a high thermal conductivity.

An object of the present invention is to provide an inorganic fiber and a refractory heat insulating material having high fiberization efficiency and low thermal conductivity.

[0012]

One of the solutions of the present invention is an inorganic fiber according to claim 1 or 2, and another solution is a refractory heat insulating material using such an inorganic fiber. is there.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The inorganic fiber of the present invention contains silica and titania as main components, or contains silica, titania and alumina as main components, and contains iron, nickel, cobalt,
Contains one or more oxides selected from copper, zirconium, niobium, zinc, and manganese.

In addition to these, the inorganic fiber of the present invention may contain an alkali metal element and an alkaline earth metal element as impurities. This impurity is present in the form of oxides.
If the content is 2% by weight or less, there is no difference in characteristics.

The inorganic fiber contains 50 to 75% by weight of silica, 10 to 49% by weight of titania, and 0 to 30% of alumina.
%, And at least one oxide selected from iron, nickel, cobalt, copper, zirconium, niobium, zinc, and manganese is 0.3 to 7% by weight. An inorganic fiber having excellent efficiency, low thermal conductivity and fire resistance can be obtained.

Silica has the function of increasing the viscosity of the melt. In order to obtain a suitable melt viscosity, the silica content is preferably 50 to 75% by weight. In this content range, the melt has an appropriate viscosity, is suitable for fiberization, and can efficiently produce desired fibers.

Titania has a lower thermal conductivity than alumina. In the alumina-silica fiber, when alumina is replaced with titania having low thermal conductivity and combined with silica having low thermal conductivity, the thermal conductivity of the fiber itself can be reduced.

Titania has a lower melting point than alumina. Therefore, when titania is contained, the melting property is improved, and the melting can be performed with little electric power. Also, when the melt containing titania is taken out as a trickle,
Since the change in viscosity due to temperature is small and the surface tension is small, fiberization can be stably performed for a long time, and the fiberization efficiency can be improved.

The content of titania is preferably from 10 to 49% by weight. When the content is less than 10% by weight, the above-mentioned effect of titania is small.
If it exceeds 49% by weight, the viscosity becomes too low, and it becomes difficult to form fibers.

Alumina has a high melting point and a function of improving the heat resistance of the fiber, but has a relatively high surface tension, and its content is preferably 30% by weight or less.

Iron, nickel, cobalt, copper, zirconium, niobium, zinc, manganese, etc., act as crystal nuclei when the fiber is heated, and promote crystallization. As a result, softening and sintering of the fibers are prevented. Further, heat resistance is improved.

Further, a small amount of these components has a function of coloring fibers and absorbing infrared rays. For this reason, the refractory heat insulating material produced by using the fiber of the present invention has a low thermal conductivity because radiant heat transfer is suppressed.

The total content of oxides such as iron, nickel, cobalt, copper, zirconium, niobium, zinc and manganese is preferably 0.3 to 7% by weight. At less than 0.3% by weight,
The effect is small, and if it exceeds 7% by weight, the thermal conductivity becomes too large.

The inorganic fibers of the present invention tend to have anatase crystals if the alumina content is low. Usually, when the content of alumina is 10% by weight or more, the inorganic fiber of the present invention is amorphous. However, when this amorphous fiber is treated at a temperature of 600 ° C. to 1000 ° C., anatase crystals precipitate. Fibers having anatase are preferred because of improved heat resistance.

On the other hand, anatase has a photocatalytic function.
Therefore, the inorganic fiber having anatase has a photocatalytic function. Inorganic fibers having a photocatalytic function are N
Decomposition of O _X, and has a validity to decomposition and removal of malodorous substances in the living space or working space. The photocatalytic function of such a fiber is further enhanced by, for example, performing an acid treatment to form a porous fiber.

The inorganic fiber of the present invention can be used as various refractory heat insulating materials, similarly to the conventional alumina silica fiber. For example, the inorganic fiber of the present invention can be used as a blank fiber as it is, subjected to needling treatment, and used as a blanket. Alternatively, it can be used as a molded product.

[0027] Such a molded article can use inorganic fibers, a binder, and if necessary, a refractory powder as a raw material. As the binder, for example, organic binders such as starch, acryl and latex, and inorganic binders such as silica sol, alumina sol and titania sol are preferable. As the refractory powder, for example, silica, titania, zirconia, alumina,
Powders such as mullite are preferred. Preferred molding methods include a press molding method in which these raw materials are kneaded and molded, an extrusion molding method, and a vacuum molding method in which a slurry in which the raw materials are dispersed in water is sucked and deposited on a porous mold. .

[0028]

EXAMPLES As raw materials of alumina, silica and titania, Bayer method alumina, frymantle sand and industrial titania were used, respectively. For oxides such as iron, nickel, cobalt, copper, zirconium, niobium, zinc and manganese, commercially available reagents were used. These raw materials were blended in various ratios to obtain blended raw materials.
50 kg of this compounding raw material was heated and melted in an electric furnace. Thereafter, the melt was taken out of the furnace as a fine stream and blown with high-pressure air to obtain fibers.

The composition and properties of this fiber are shown in Tables 1 and 2. Table 1 shows examples of the present invention, and Table 2 shows comparative examples that do not fall within the scope of the present invention.

[0030]

[Table 1]

[Table 2] The characteristics in Tables 1 and 2 will be described.

The viscosity stability is represented by the time from when the heating is stopped and the melt is taken out of the furnace as a small stream, until the melt is cooled and solidified to obtain no small stream. The longer the time, the smaller the change in viscosity.

The thermal conductivity was determined by adding a fiber and starch to water to form a slurry, and forming the slurry into a predetermined shape by vacuum forming using a molded product having a bulk density of 0.4 g / cm ³ as a sample. It was measured by the method.

However, in Example 4, a mixture of 100 parts by weight of fiber, 300 parts by weight of silica flower and 600 parts by weight of titania powder, and 50 parts by weight of silica sol and an acrylic binder were added to 1000 parts by weight of these mixtures. 50 parts by weight and 1.0 part by weight of the cationic coagulant were added to water to form a slurry.

The amount of shots that did not pass through a 62 mesh screen was measured.

The heat shrinkage was measured using the same sample as the sample whose thermal conductivity was measured.

FIGS. 1 and 2 relate to Example 5 and Comparative Example 1.
It is a SEM photograph after heating at 1200 ° C for 24 hours. These Figures 1 ~
From 2, it is understood that Example 5 has no softening and sintering and is excellent in heat resistance.

Example 4 is an example in which the thermal conductivity of the molded product is extremely low.

In Comparative Example 1, iron, nickel, cobalt,
This is an example that does not contain copper, zirconium, niobium, zinc, manganese, and the like. Comparative Example 1 has a large shrinkage at 1200 ° C.

Comparative Example 2 is an example in which the amount of iron is large. Large thermal conductivity.

Comparative Example 3 is an example in which the amount of silica is small. Low viscosity, many shots.

Comparative Example 4 is an example containing a large amount of silica. The meltability was poor, and fibers could not be obtained.

Comparative Example 5 is an example in which titania is small.
Low viscosity stability and poor heat insulation.

[0043]

According to the inorganic fiber of the present invention, it is easy to produce a fiber having a small number of shots. By appropriately adjusting the composition, a melt having a small change in viscosity and a low surface tension can be easily obtained, and the production of the inorganic fiber is easy. Performance can be improved.

Further, the inorganic fiber of the present invention is a fiber having heat resistance, lower thermal conductivity than alumina silica fiber, and excellent heat insulation.

The inorganic fiber of the present invention can be used as a material for a refractory heat insulating material having excellent performance.

The refractory heat insulating material of the present invention has a safe use temperature of 1200
Heat resistance of about ° C is obtained. Moreover, since the refractory heat-insulating material of the present invention is more excellent in heat-insulating properties than using the conventional alumina-silica fiber, it is possible to reduce the size of the device for insulating the high-temperature portion.

[Brief description of the drawings]

FIG. 1 is an SEM photograph of Example 5.

FIG. 2 is an SEM photograph of Comparative Example 1.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Osamu Omiya 4-4 Nihonbashi Hisamatsucho, Chuo-ku, Tokyo Itoshige Building Inside Toshiba Monoflux Co., Ltd. (72) Inventor Takashi Nemoto 4th Nihonbashi Hisamatsucho, Chuo-ku, Tokyo No. 4 Itoshige Building Toshiba Monoflux Co., Ltd. (72) Inventor Masaru Sugiyama 4-4 Nitohashi Hisamatsucho, Chuo-ku, Tokyo Itoshige Building Toshiba Monoflux Co., Ltd. F-term (reference) 4L037 CS20 CS23 FA05 PA31 PF07 UA07

Claims (3)

[Claims] 1. Silica is 50-75% by weight, titania is 10-49% by weight, alumina is 0-30% by weight, iron, nickel, cobalt, copper, zirconium, niobium, zinc, manganese At least one oxide selected from the group consisting of 0.3
Inorganic fiber, characterized in that it is about 7% by weight. 2. The inorganic fiber according to claim 1, comprising an anatase crystal. 3. A fire-resistant heat insulating material using the inorganic fiber according to claim 1 or 2.