JPH01212270A - Uncalcined carbon-containing brick and binder composition used for production thereof - Google Patents

Abstract

PURPOSE:To provide the title brick which is of the prescribed value or below in the ratio of compression modulus/compressive strength and is excellent in spalling resistance, oxidation resistance, etc., by mixing a binder mixture composed of a specific compsn. with a mixture composed of a refractory material and carbon, then molding the mixture and drying the molding. CONSTITUTION:The binder mixture is produced by mixing a resin (e.g.; phenolic resin) contg. a monomer (e.g.; phenol) as well as tar and pitch. This binder mixture is then mixed with the mixture composed of the refractory material (e.g.; magnesia, alumina) and the carbon (e.g.; graphite) and the mixture is molded. The molding is dried by heating to >=200 deg.C in a nonoxidizing atmosphere. The uncalcined carbon-contg. brick having <=50 ratio of compression modulus/compressive strength when the compression modulus and the compressive strength are expressed in the same unit is thereby obtd. and, therefore, the amt. of the carbon to be added is decreased and the low-carbon brick is easily produced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electric furnace, converter, ladle, and RH furnace for steelmaking.

The present invention relates to unfired carbon-containing bricks used for lining degassing containers such as DH furnaces, and a binder composition used in the production thereof.

[Conventional technology]

Conventionally, tar and pitch produced during petroleum carbonization have been used as binders for unfired carbon-containing bricks such as unfired magnesia carbon bricks.

This tar and pitch are baked at 350 to 550°C for a relatively long time to promote carbonization, and then baked at 150 to 550°C for a relatively long time.
By firing at a temperature of 0°C or higher for a long time, free carbon is converted into graphite and soft carbon, creating a carbon bond that is resistant to thermal shock.

However, to generate carbon bonds, tar and pitch require long-term heating at high temperatures, which consumes a large amount of energy, and when heated, they generate carcinogenic substances and pollute the atmosphere. It has its drawbacks.

For this reason, in recent years, tar and pitch have been replaced by 20
Thermosetting resins such as phenol resins and furan resins, which are easily cured at relatively low temperatures of 0° C. or lower and have good carbonization yields, have come into widespread use.

In particular, phenolic resin is available in powder form and liquid form.

Not only can the properties of the resin be arbitrarily created depending on the purpose and method of use, such as festivals, but the cured resin begins to carbonize at around 350°C, and the carbon produced is extremely hard and has high mechanical strength. There is an advantage.

[Problem to be solved by the invention]

However, on the other hand, when a phenolic resin is used as a binder, it has the disadvantage that it has expandability, is susceptible to thermal shock, and has low oxidation resistance compared to the case of tar or pitch.

This means that the carbon generated from phenolic resin is 1500
Graphitization does not occur even when heated above ℃, and it remains amorphous carbon.Also, since the cured resin is insoluble and infusible to heat, when it is carbonized as it is, the porosity increases and the specific surface area decreases. It is said that this is to grow bigger.

Therefore, in order to complement each other's shortcomings,
Attempts have been made to mix tar, pitch and phenolic resin, or to use modified phenolic resin.

However, while tar and pitch are non-polar, phenolic resin is highly polar and therefore has poor compatibility.
In addition, even if they are mixed when hot, they will separate as the temperature decreases, impairing uniform dispersion, and the disadvantage will be greater.
It has not yet reached actual use. It is also possible to use a solvent that uniformly dissolves these, but it is undesirable because it has poor reactivity and most of it evaporates during heat curing, and the binder moves with the solvent, resulting in a non-uniform cured product.

The purpose of the present invention is to solve the above-mentioned problems when using a mixture of tar, pitch, and phenol resin as the conventional unfired carbon-containing binder, and to find a binder that can obtain a cured product that can be uniformly dispersed with tar and pitch. , thereby obtaining an unfired carbon-containing brick that takes advantage of the functions of tar and pitch and has excellent oxidation resistance and spalling resistance.

[Means to solve the problem]

In the present invention, when tar, pitch, and a resin binder are mixed and used as a binder for unfired carbon-containing bricks, the resin binder used has good compatibility with the tar and pitch, and moreover, the resin binder itself is carbonized. Tar, pitch and resin can be used as a binder for unfired carbon-containing bricks by blending additives that contribute to the bonding reaction and have the function of easily coupling with tar and pitch and not inhibiting mutual separation or migration. This eliminates the above-mentioned drawbacks when using a mixture of binders.

That is, the present invention was completed by paying attention to the fact that the characteristics of the monomer of the resins that are the raw materials for synthesizing the binder resin have the above-mentioned functions, and by coming up with the formulation of this monomer in the binder.

Phenol resin is good as the resin to be used, but among phenols, alkylphenols with many side chains are effective because they easily dissolve tar and pitch. Specifically, phenols include phenol, cresol,
nonylphenol, butylphenol, xylenol,
Chlorophenol etc. can be used.

Although the content of 7-mer differs depending on the molecular weight of the base resin and the mode of use, it is desirable that it is present in an amount of 10% or more based on the HLC analysis method based on the base resin.

A resin containing such a monomer can be prepared by incompletely converting the monomer into a resin, but the monomer may also be blended into a phenol resin that has been completely converted into a resin.

In addition, in order to provide workability as a binder,
It is preferred to use a small amount of a solvent, preferably a reactive solvent, which makes both the base resin and monomer compatible.

Further, it is preferable that the tar and pitch used be those with a low content of benzene-insoluble content that inhibits uniform carbonization.

The mixing ratio of tar, pitch, and binder resin such as phenolic resin can be changed arbitrarily depending on the required physical properties, but in the case of phenolic resin, the weight ratio of phenolic resin containing monomer/tar, pitch is 90%.
It is preferably between /10 and /20 /80. If the mixing ratio of the phenolic resin containing monomer is more than this, the rigidity will increase, and if it is less than this, the curing performance will be poor, which is not preferable.

For example, phenolic resin containing a large amount of phenol, which is a monomer of phenolic resin, can be arbitrarily miscible with tar and pitch, and by using an appropriate curing agent together, it can be volatilized or separated both at room temperature and when heated. Instead, it turns into a polymer and becomes three-dimensional while retaining tar and pitch in an insoluble and infusible state.

That is, it is possible to obtain both the property of a thermosetting resin that it can be cured at a low temperature, and the properties of tar and pitch, which are excellent in oxidation resistance and impact resistance.

In particular, when this cured product is fired in a reducing atmosphere, the specific gravity increases and the oxidation initiation temperature becomes high, and when looking at the X-ray diffraction pattern, a peak indicating graphitization is obtained by low-temperature firing. As a result, the obtained cured product has a uniform sea-
It becomes an island pattern, the elastic modulus decreases, and the spalling resistance and oxidation resistance improve.

As a result, when the above binder is used, an unfired carbon-containing brick having a compressive modulus/compressive strength of 50 or less after drying at 200° C. in a non-oxidizing atmosphere can be obtained. This has the effect of reducing the amount of carbon added and facilitates the production of low carbon bricks.

In the case of the present invention, the refractory material includes not only magnesia but also
It is also possible to use non-oxide materials such as alumina, spinel, magne-alime, zirconia, zircon, S+C, Sia N4, etc.

Using the binder of the present invention, a mixed binder of a resin containing a monomer, tar, and pitch is blended with a mixture of a fireproof material and carbon, and the binder is mixed in a non-oxidizing atmosphere.
The ratio of compressive elastic modulus/compressive strength is 50 when compressive elastic modulus and compressive strength are expressed in the same unit after drying at 00°C or higher.
The following unfired carbon-containing bricks can be obtained.

Furthermore, compared to bricks using conventional novolac type phenolic resin, it has a high carbon content (carbon content of 15%).
~25%), there is a significant improvement in oxidation resistance and corrosion resistance, and in the low carbon range (carbon content 15~5%), not only oxidation resistance but also corrosion resistance, especially spalling resistance, is significantly improved. Is recognized.

〔Example〕

[1] Preparation of monomer-containing resin a. Phenol resin 1 (novolac type) 940 g of phenol and 405 g of 37% formalin were placed in a four-loaf flask (No. 21), and oxalic acid (9.
Added 4g. The mixture was refluxed for about 60 minutes while stirring, and the reaction was continued for 120 minutes, followed by normal pressure hydrophilization to 150°C.

The obtained resin is a viscous liquid with a viscosity of 20 at 25°C.
0 Poise. In addition, the residual amount of phenol as a reactive compatibilizer by high-performance liquid chromatography was 2
It was 8%.

Mouth, phenolic resin 2 (novolac type) phenol 470 g, para-cresol 540 g, 37
% Formalin 568g was placed in a 21-inch four-loaf flask,
To this was added 9.4 g of sidiic acid as a catalyst.

It took about 60 minutes to reflux while stirring, and then it was left to reflux for about 12 minutes.
After reacting for 0 minutes, dehydration was performed at normal pressure to 150°C.

The resulting resin had a softening point of 60° C. and a residual amount of phenols of 13%. Add phenol to this resin for 10 minutes.
%, and 5% of cyclohexanone was added as a reactive solvent. The resulting resin was a viscous liquid with a viscosity of 150 poise at 25°C.

Moreover, the content of phenols was 22%.

C. Phenol resin 3 (resol type) Phenol 9
40 g of 37% formalin (892 gt) was placed in a four-loop flask, and to this was added a 50% aqueous solution of caustic soda.
7.6 g was added. It took about 60 minutes to raise the temperature to 70°C, and the reaction was carried out at 70±3°C for 2 hours. Dehydration under reduced pressure was started and continued at 150 torr until the internal temperature reached 70°C. The resulting resin was a viscous liquid with a viscosity of 80 poise at 25°C. Further, the residual amount of phenol was 15%.

(2) Preparation of tar, pitch A. Tar, pitch 1 Viscosity at 25°C 30 pores Benzene insoluble content 11% Fixed carbon content 22% Mouth, tar, pitch 2 Softening point 50°C Benzene insoluble content 19% Fixed carbon content 51% This tar, 50 parts by weight of pitch, 1 part of acetophenone
0 parts by weight were mixed to obtain a liquid having a viscosity of 150 poise at 25°C.

(3) Manufacture of magnesia carbon bricks Add and blend the binder shown in the binder section of the same table to the aggregate in the proportion shown in Table 1, knead for 15 minutes in a Ni-Goo, and form it. Test pieces shown in Nα1-20 were obtained. These were dried in a dryer set at 200 tons for 3 hours to obtain the results shown in the characteristics section of the same table. Each characteristic value in the same table is the result of the following procedure.

The anti-pressure test was conducted at a loading rate of 2 m+n/min, and the elastic modulus was measured when the load of the test piece was between 25 and 37.5 kgf/cm''.

Also, the spalling test is 50 x 50 x 50m
The occurrence of cracks was investigated after a test piece of No. m was immersed in hot pig iron at 1600°C and cooled in water five times.

On the right side of the same table, ◎ means no cracks, O means cracks, and X means cracks.
Indicates the state of peeling.

Furthermore, in the oxidation test, when the above test piece was left in air at 800 °C for 4 hours, the decarbonized thickness was 5++.
Un or more is represented by X, and less than 5 mm is represented by Q.

(Hereafter, this page margin) 〔Effect of the invention〕 The present invention can provide the following effects.

(1) A binder can be obtained which has both the property of a thermosetting resin that it can be cured at a low temperature and the properties of tar and pitch that provide a carbon bond with excellent oxidation resistance and impact resistance.

(2) Unfired carbon-containing bricks with improved spalling resistance and oxidation resistance can be obtained.

Claims (6)

[Claims] 1. It is made by blending a mixture of fireproofing material and carbon with a mixed binder of resin containing monomers, tar, and pitch, and the compressive elastic modulus and compressive strength after drying at 200°C or higher in a non-oxidizing atmosphere. An unfired carbon-containing brick characterized in that the ratio of compressive elastic modulus/compressive strength when expressed in the same unit is 50 or less. 2. A binder composition for unfired carbon-containing bricks, characterized in that the binder is a mixture of a resin binder, tar, and pitch, and contains a monomer of the resin. 3. The binder composition for unfired carbon-containing bricks according to claim 2, wherein the resin binder is a phenolic resin and the monomer is a phenol. 4. 3. The binder composition for unfired carbon-containing bricks according to claim 2, wherein the monomer content is 10% or more based on the base resin as measured by HLC analysis. 5. 3. The binder composition for unfired carbon-containing bricks according to claim 2, wherein the binder contains a solvent that makes both the base resin and the monomer compatible. 6. The weight ratio of the mixed binder of phenolic resin containing monomer, tar, and pitch is 90/10 to 20/
The binder composition for unfired carbon-containing bricks according to claim 2, characterized in that the binder composition has a hardness of between 80 and 80.