JPS62109B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a refractory composition used for lining refractory furnace materials such as blast furnaces, pig iron mixers, converters, ladles, and tundishes, and lower nozzles of sliding nozzles in continuous casting. Conventionally, refractories manufactured by firing at 1000 to 1500°C have generally been used. However, firing this refractory requires a huge amount of energy, which is not preferable in terms of energy conservation. Therefore, unfired refractories made by bonding refractory aggregates with thermosetting resin binders are attracting attention. This unfired refractory is made by pressing and shaping a mixed composition of refractory aggregate and thermosetting resin, and hardening and drying it by heating it at a temperature of about 200°C. When used, the molten steel is fired at a high temperature, and no firing process is required during manufacture. Such a refractory composition is prepared by kneading the thermosetting resin dissolved or dispersed in a solvent in order to improve the wetting of the thermosetting resin to the refractory aggregate. Methanol and ethanol are often used as such solvents, but since these have low flash points and are dangerous, ethylene glycol has recently been widely used. However, since this solvent is evaporated during the heating and drying process, it does not contribute to the production of the final fired product and is extremely uneconomical.
In addition, in this case, the solvent evaporates, making the refractory porous and easily damaged by molten steel.
Another problem was that the service life of the refractories was short. The present invention has been made in view of the above points, and is economical because it can act as a binder without simply evaporating the solvent.
Moreover, it is an object of the present invention to provide a composition for refractories that can provide long-life refractories. That is, the composition for refractories of the present invention is characterized by blending a refractory aggregate, a thermosetting resin as a binder, and acetophenone and/or cyclohexanone as a solvent for the thermosetting resin. The above object is achieved because acetophenone and cyclohexanone turn into resin when heated. The present invention will be explained in detail below. As the thermosetting resin binder, resol type or novolak type phenolic resin or furan resin is mainly used. Phenol resins and furan resins are optimal because they have a large amount of residual carbon and are cheap. The thermosetting resin is dissolved in a solvent and kneaded with a refractory aggregate to obtain a composition for refractories, and acetophenone and cyclohexanone are used alone or in combination as the solvent. Acetophenone

[Formula] is boiling point 202℃, cyclo hexanone

[Formula] has a boiling point of 156℃, and aldehydes such as formalin and hexamethylenetetramine act as hardening agents and are easily converted into ketone resins, so aldehydes and hexamethylenetetramine are added to the refractory composition. It is preferable to keep it. Highly purified acetophenone or cyclohexanone is preferred, but those containing recovered material after use as a solvent or pot residue can also be used. When a novolak type phenolic resin is used as the thermosetting resin, hexamethylenethramine is blended in an amount greater than that consumed by the novolak type phenolic resin. The blending ratio of the solvent to the thermosetting resin varies depending on whether the thermosetting resin is liquid or solid, but for example, in the case of liquid novolac type phenolic resin or liquid resol type phenolic resin, it is 10 to 15. In the case of solid novolak type phenolic resin and solid resol type phenolic resin, the amount is preferably about 30 to 50% by weight. In addition, commonly used refractory aggregates can be used; examples include waxite, clay, shale, baked clay, earthen shale, synthetic mullite, sintered alumina, zircon, zirconia,
These include magnesia, chromite, phosphorous graphite, and dolomite clinker. However, a composition for refractories is obtained by blending a mixture of a thermosetting resin and a solvent with refractory aggregate, and this composition is press-molded and shaped.
The thermosetting resin is cured by heat treatment at a temperature of about 200°C. At this time, the solvents such as acetophenone and cyclohexanone are cured and turned into a ketone resin without evaporation, and some of them are co-condensed with phenol and furan to form a polymer. Therefore, at this stage, the residual carbon of the ketone resin is added to the residual carbon of the thermosetting resin, resulting in an increase in the residual carbon of the refractory. When the refractory thus formed and heat-treated is used in an actual furnace, the refractory is fired by the high temperature of the molten steel, and the thermosetting resin and ketone resin are carbonized. At this time, since the amount of residual carbon has increased, a large amount of carbonized components can be contained in the refractory. As mentioned above, the composition for refractories according to the present invention,
Since it is a mixture of refractory aggregate, a thermosetting resin as a binder, and acetophenone and/or cyclohexanone as a solvent for the thermosetting resin, acetophenone and cyclohexanone are used during molding and heat treatment of the refractory composition. It does not turn into a ketone resin and all of it evaporates and disappears, and the acetophenone and cyclohexanone used as the solvent can also act as a binder. The amount of residual carbon in the product can be increased by using ketone resin, and the amount of carbon component in the fired refractory can be increased. Because of this effect, it is possible to improve the strength of the refractory, and it is also possible to reduce the amount of thermosetting resin blended as a binder, thereby reducing costs. In addition, acetophenone and cyclohexanone as solvents are not evaporated, so
There is no fear that the porosity of the refractory will increase, and the melting loss of the refractory can be reduced and the life of the refractory can be extended. Next, the present invention will be specifically explained using examples. Preparation of Γ thermosetting resin binder (2) 940 g of phenol, 424 g of 92% paraformaldehyde, 630 g of water, and 7.5 g of lithium hydroxide were placed in a four-necked flask and heated to 70° C. over about 90 minutes. The reaction was continued for 180 minutes, and after the reaction was completed, the pressure was gradually reduced to 650 mmHg.
Dehydration was performed under reduced pressure until the internal temperature reached 75°C. The obtained resol type phenolic resin was a brown liquid with a water content of 3%, an average molecular weight of 350, and a viscosity of 130 poise at 25°C. To the thus obtained resol type phenolic resin, 10% by weight of acetophenone and 3% by weight of hexamethylenetetramine were added and mixed. Preparation of Γ thermosetting resin binder () The procedure was the same as in () above except that cyclohexanone was used instead of acetophenone. Preparation of Γ thermosetting resin binder () The procedure was the same as in () above except that ethylene glycol was used instead of acetophenone and hexamethylenetetramine was not blended. Preparation of Γ thermosetting resin binder () Put 940 g of phenol, 228 g of 92% paraformaldehyde, 340 g of water, and 7.5 g of oxalic acid into a four-necked flask, reflux for 60 minutes, and continue the reaction for 150 minutes. Ta. After the reaction was completed, dehydration was started at normal pressure and concentration was continued until the internal temperature reached 150°C. The obtained novolak type phenolic resin was a viscous liquid with a water content of 1.0%, an average molecular weight of 450, and a viscosity of 350 poise at 25°C. To the thus obtained novolak type phenolic resin, 50% by weight of acetophenone and 15% by weight of hexamethylenetetramine were added and mixed. Preparation of Γ thermosetting resin binder () The procedure was the same as in () above except that ethylene glycol was used instead of acetophenone. Preparation of Γ thermosetting resin binder () Place 980 g of furfuryl alcohol and 163 g of 92% paraformaldehyde in a four-necked flask.
The pH was adjusted to 3.0 with 50% phosphoric acid aqueous solution. After refluxing for 60 minutes and continuing the reaction for 180 minutes, 130 ml of water was dehydrated under reduced pressure of 650 mmHg. The obtained furan resin is a blackish brown liquid with a moisture content of 0.5% and an average molecular weight of 290.
The viscosity was 13 poise. Further, 3% by weight of a 50% zinc chloride aqueous solution was added as a latent curing agent to the furan resin thus obtained, and the mixture was thoroughly mixed. 10% by weight of acetophenone and 10% by weight of hexamethylenetetramine were added to this furan resin and mixed. Preparation of Γ thermosetting resin binder () The procedure was the same as in () above except that cyclohexanone was used instead of acetophenone. Preparation of Γ thermosetting resin binder () The procedure was the same as in () above except that ethylene glycol was used instead of acetophenone and hexamethylenetetramine was not blended. <Example 1> A refractory aggregate consisting of 95% by weight of waxite and 5% by weight of clay was thoroughly mixed with 8% by weight of the binder obtained in () above based on the total amount, and this composition was
Molded into a size of 114 x 230 mm, this molded product was
An unfired refractory was obtained by heating and curing and drying at ℃ for 24 hours. <Example 2> 8% by weight of the binder obtained in ()
An unfired refractory was obtained in the same manner as in Example 1 except for using the following materials. <Example 3> An unfired refractory was obtained in the same manner as in Example 1 except that 6% by weight of the binder obtained in () was used. <Comparative Example 1> 8% by weight of the binder obtained in ()
An unfired refractory was obtained in the same manner as in Example 1 except for using the following materials. Table 1 shows the physical properties of the unfired refractories obtained in Examples 1 to 3 and Comparative Example 1. According to the results in Table 1, it was confirmed that each Example had a smaller apparent porosity than that of Comparative Example 1, and Examples 1 and 2 had the same amount of binder as Comparative Example 1.
The strength of Example 3 is higher than that of Comparative Example 1, and even the Example 3 with a reduced amount of binder has a higher strength than Comparative Example 1.
It is confirmed that the strength is equivalent to that of

[Table] <Example 4> To the fireproof aggregate consisting of 85% by weight of magnesia and 15% by weight of scaly graphite, 4.3% by weight of the binder obtained in () above was added to the total amount of these and mixed well.
An unfired refractory was obtained in the same manner as in Example 1. <Example 5> An unfired refractory was obtained in the same manner as in Example 4, except that 3.0% by weight of the binder obtained in () was used. <Comparative Example 2> An unfired refractory was obtained in the same manner as in Example 4, except that 4.3% by weight of the binder obtained in () was used. The physical properties of the unfired refractories of Examples 4 and 5 and Comparative Example 2 are shown in Table 2. The results in Table 2 show similar trends to those in Table 1.

[Table] <Example 6> To a fireproof aggregate consisting of 85% by weight of magnesia and 15% by weight of scaly graphite, 3.7% by weight of the binder obtained in the above () was added to the total amount of these and mixed well.
The rest was carried out similarly to Example 1 to obtain an unfired refractory. <Example 7> An unfired refractory was obtained in the same manner as in Example 6 except that the binder obtained in () above was used. <Example 8> An unfired refractory was obtained in the same manner as in Example 6, except that 3.0% by weight of the binder obtained in () was used. <Comparative Example 3> As a binder, the binder obtained in () above was used at 3.7
An unfired refractory was obtained in the same manner as in Example 6 except that the weight percent was used. Table 3 shows the physical properties of the unfired refractories obtained in Examples 6, 7, and 8 and Comparative Example 3.

[Table] It is confirmed that results showing the same tendency as in Table 1 were obtained in Table 3 above.

Claims (1)

[Scope of Claims] 1. A refractory composition comprising a refractory aggregate, a thermosetting resin as a binder, and acetophenone and/or cyclohexanone as a solvent for the thermosetting resin. 2. The composition for refractories according to claim 1, characterized in that hexamethylenetetramine is used in combination. 3. The composition for refractories according to claim 1 or 2, characterized in that an aldehyde is used in combination.