JPS5828229B2 - Fushiyousei Tai Karenga no Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing unfired refractory bricks.

More specifically, in producing an unfired refractory brick, the present invention uses three types of powdered thermosetting resin as a binder for the clay, a solvent and a non-solvent for the resin, and The mixture ratio with the non-solvent is changed as appropriate depending on the shape of the target brick, the molding conditions such as the molding method, etc., and after heat treatment at a temperature near the boiling point of the non-solvent, a normal baking treatment is performed to form various shapes. The present invention relates to a manufacturing method for obtaining excellent unfired refractory bricks.

Conventionally, in order to take advantage of carbon's refractory wettability to molten steel slag, high thermal conductivity, and high corrosion resistance, unfired bricks or Unfired refractory 75 made by adding solid carbon raw material to the refractory aggregate and using coal tar pitch as a binder has been used.

This type of refractory has been used in a state where it is usually subjected to hazing at a temperature of around 300° C. for more than 10 hours, and a portion of the coal tar pitch (7) is carbonized and a considerable amount of volatile matter still remains.

However, in such a refractory brick in which the coal tar pitch, which is a binder, is not completely carbonized and solidified, the strength of the connective tissue of the brick is extremely reduced in the intermediate temperature range of 200 to 500° C. when receiving heat.

In particular, when the heating rate is high, this tendency is even more pronounced, resulting in the brick structure becoming completely brittle and becoming unusable.

In addition, coal tar pitch has a strong odor and contains a large amount of substances harmful to the human body, such as nitrogen-containing compounds and oxygen-containing compounds. There is a problem.

When manufacturing large-sized broken bricks, a uniaxial hydraulic press results in uneven pressure distribution, which can cause cracks during brick manufacturing or use. ), bulk molding and other molding methods are used, but in order to enhance the filling effect of the clay during molding, the binder must have a low viscosity, and for this reason, in the case of coal tar pitch binders, creosote Since it is used after being extremely diluted with a solvent such as oil or anthracene oil, the carbonization yield is low, the strength after molding and baking is low, and the life of the brick is short.

Various attempts have been made to improve the drawbacks caused by the use of coal tar pitch binders as described above.

For example, a method has been proposed in which a thermosetting resin binder such as liquid phenol resin or liquid furan resin with a relatively high amount of fixed carbon is kneaded at room temperature, and this method improves the softening phenomenon in the intermediate temperature range of 200 to 500 degrees Celsius and improves production. The method has been successfully simplified.

However, when molding large products, it is necessary to lower the binder viscosity in order to improve the filling properties during molding, and a large amount of dilution with a solvent is required, which results in a lower carbonization yield and lower raw corner strength after molding. This causes problems in the handling of molded bricks.

The baking strength of the casing is low, and since a large amount of solvent is used, cracks are likely to occur during baking.

The present invention was completed as a result of repeated research to eliminate these drawbacks. The present invention relates to a method of manufacturing excellent unfired bricks of various shapes by adding a thermosetting resin and further adding a mixed solution of a solvent and a non-solvent for the resin.

The effects of the present invention are achieved by the combined use of a powdered thermosetting resin button and a mixed solution of the resin bath agent and a non-solvent.

When only a powdered thermosetting resin and a solvent are used, the powdered thermosetting resin releases almost δ volume during kneading and is shaken, resulting in a decrease in the flow ratio of the clay, resulting in poor filling properties during molding, resulting in a dense mold. A molded body cannot be obtained.

On the other hand, when only a powdered thermosetting resin and a non-solvent are used, the elution and swelling of the powdered thermosetting resin does not occur at all when the wires are crossed, so the raw corner strength after molding is extremely small, causing difficulty in handling the molded product. At the same time, the degree of softening, fluidization, and dispersion of the powdered resin during subsequent heat treatment is small, making it impossible to obtain a homogeneous product.

The present inventors used a mixed solution of a solvent and a non-solvent, and changed the mixing ratio according to the shape of the intended brick or the molding conditions such as the molding method. By being able to adjust the degree of elution and swelling, it is possible to obtain clay suitable for each molding condition, and by heat treatment at a temperature near the boiling point of the non-solvent, the powdered resin is softened, fluidized and dispersed, resulting in a homogeneous and good product. This is what I discovered that can be done.

For example, small-sized products using a hydraulic press 65 x 114 x 2
In the case of 30 tones, the mixing ratio of solvent and non-solvent is 50:
50, large-sized product using vibration press 5
In the case of 00X500X500yym+, by setting the ratio to 20:80, the degree of elution of the powder resin becomes optimal for the molding conditions, and the molded product immediately after molding has good filling properties, so the bulk specific gravity is high and there are no cracks. , and has high strength, making it easy to handle molded products.

By heat-treating the molded product at a temperature close to the boiling point of the non-solvent, the strength is further increased and the structure becomes homogeneous.Finally, the product obtained by regular baking treatment has very good physical properties and strength. and when used 200~5
No softening phenomenon occurs in the intermediate temperature range of 00°C.

Since the method of the present invention uses the thermosetting resin in the form of a solid powder, there is little odor, and there is little change over time after it is mixed into the aggregate, which greatly improves the efficiency of the working environment.

The product according to the present invention is produced by adding 2 to 20 parts of a powdered thermosetting resin to 100 parts of aggregate selected from refractory oxides, nitrides, borides, carbides, solid carbon raw materials, etc. according to the purpose of use. After mixing, 3 to 10 parts of a mixed solution prepared by premixing the solvent and non-solvent of the resin, which are liquid at room temperature, at a ratio of 1:9 to 9:1 depending on the molding conditions, are added, and the mixture is kneaded and molded at room temperature. After heat treatment at a temperature near the boiling point of the non-solvent,
Obtained by normal baking treatment at around ℃.

The powdered thermosetting resin used in the present invention is, for example, phenol resin, melamine resin, urea resin, etc. powder of 100 mesh or less, which is used in an amount of 2 to 20 parts per 100 parts of aggregate, but it leaves a large amount of residual carbon when decomposed at elevated temperatures. It is preferable to use a phenolic resin and the softening point is preferably 100°C or less.

If the softening point is 100° C. or higher, the degree of softening, flow and diffusion of the powdered thermosetting resin during heat treatment at a temperature near the boiling point of the non-solvent will be small, and the structure after drying will not be homogeneous.

The powdered thermosetting resin causes a thermosetting reaction when heated and forms a three-dimensional structure, so it prevents the softening phenomenon in the intermediate temperature range of 200 to 500°C during use of the baked product and improves hot strength. Shows effect on improvement.

If the amount of powdered thermosetting resin added is less than 2 parts, the amount of residual carbon after baking will decrease and the strength will deteriorate, which is undesirable. If it is more than 20 parts, the pores after baking will decrease. Since the ratio increases, the amount added is preferably 2 to 20 parts.

In the combination of a solvent and a non-solvent, the boiling point of the solvent must be higher than the boiling point of the non-solvent, and the two must be mutually soluble.

In addition, the solvent for powdered thermosetting resins must be liquid at room temperature and have a boiling point of 300°C or lower, which is 20°C or more higher than the non-solvent, and the non-solvent must be liquid at room temperature and have a boiling point of 150°C or lower. It's light and heavy.

For example, when phenolic resin is used as a powdered thermosetting resin, alcohols, especially dihydric alcohols such as ethylene glycol and triethylene glycol, are used as the solvent, and water is used as the non-solvent and mixed and dissolved in advance. used.

By changing the mixing ratio according to the molding conditions as described above, a clay suitable for each molding condition can be obtained.

Next, the present invention will be specifically described with reference to Examples.

The above mixture was kneaded at room temperature, and the mixture was kneaded with a hydraulic press.
oH/cr? Formed into a 65 x 114 x 230 cabinet shape with a molding pressure of r, heated at 100 °C for 5 hours after molding, and
Bake for 0 hours.

The characteristics of the obtained product are shown in Table 1 in comparison with the % properties of the conventional product.

In other words, the particle size, formulation, molding method, and baking treatment method of the conventional refractory raw material were the same as in this example, except that 5 parts by weight of coal tar pitch was added to the rehinder and 5 parts by weight of resol type phenol liquid resin was added. The results are also shown below.

The above compound was kneaded at room temperature and molded into a 500x500x500-shape using a vibration press, at 100°C after molding.
The mixture was heated for 24 hours and baked at 300°C for 15 hours.

Characteristics of the obtained product (1) Comparison with the characteristics of conventional products are shown in Table 2.

The particle size, formulation, molding method, and baking treatment method of the conventional refractory raw material were the same as in this example, and 5 parts by weight of coal tar pitch and 5 parts by weight of resol type phenolic liquid resin were added to the binder. The items are also shown.

The above mixture was kneaded at room temperature and molded into a 500x500x500wn shape using a vibration press. After molding, it was heated at 100°C for 24 hours and baked at 300°C for 15 hours.

The characteristics of the obtained product are shown in Table 3 in comparison with those of conventional products.

The particle size, formulation, molding method, and baking treatment method of the conventional refractory raw material were the same as in this example, except that 5 parts by weight of coal tar pitch and 5 parts by weight of resol type phenolic liquid resin were added to the binder. The items are also shown.

As shown in Examples 1, 2, and 3, it is clear that the product of the present invention has extremely high strength after molding and strength after baking compared to conventional products, and has a large bulk specific gravity and excellent filling properties. .

When the product of the present invention was put to practical use in electric furnace tapping troughs, electric furnace hot spots, etc., it was found that the product life was approximately 30% longer than conventional products.

Claims (1)

[Claims] 1. Production of unfired refractory bricks, which is characterized by adding a mixed solution of a powdered thermosetting resin, a solvent for the resin, and a non-solvent to the refractory raw material. Law.