JPH0812453A - Monolithic refractory composition - Google Patents

Abstract

PURPOSE:To obtain high fluidity, extension and rapid hardening properties in monolithic refractory by previously crosslinking a phenol resin as a binder and blending the phenol resin with a refractory aggregate. CONSTITUTION:This monolithic refractory composition comprises a phenol resin having crosslinking structure. For example, (1) a phenol resin which is obtained by blending a novolak phenol resin with a crosslinking agent (e.g. hexamethylenetetramine) and crosslinking by heating, (2) a phenol resin obtained by cross-linking a resol phenol resin under heating or with crosslinking agent or (3) a phenol resin obtained by crosslinking a novolak and resol mixed phenol resin by heating or with the crosslinking agent may be cited as the phenol resin. The phenol resin has preferably 5-95% acetone extraction ratio. The powder of the phenol resin has preferably 10-3,000mum average particle diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied as a binder for refractory aggregates for amorphous refractories.

[0002]

2. Description of the Related Art Tar and pitch have been used as binders for refractories forming carbon bonds for a long time, but raw materials can be kneaded at room temperature, the refractory has high dry strength, and the refractory is manufactured. In recent years, the refractory mainly containing a phenol resin as a binder has been often produced due to the improvement of the working environment. Phenolic resins for refractories are widely used not only for regular refractories but also for irregular refractories.For example, graphite, magnesia, alumina and other aggregates for repairing furnace walls and bottoms of steelmaking equipment. A mixture of phenol resin as a binder,
Increasingly, it is used in construction methods such as pouring, stamping and spraying. Typical examples of binders based on these phenolic resins used are solid or powdered phenolic resins combined with wetting agents such as polyhydric alcohols and water, and novolac type phenolic resins in advance. There are those dissolved in polyhydric alcohol, liquid resole resin of water solvent, resole resin of polyhydric alcohol solvent, and the like.

[0003]

As described above, various types of phenolic resins have been used as binders for amorphous refractories. The characteristics required for such medium phenol resin vary depending on the actual application and construction method,
In order to improve the construction efficiency, there are many demands for high fluidity and rapid hardening. Regarding this high flow developability and fast curing property, the resin content, solvent species, solvent amount, etc. have been adjusted to select a formulation that is suitable for the purpose of use, but these properties tend to be contradictory. If it is attempted to improve the curing time, it takes a long time to cure, and on the contrary, if the curing time is attempted to be shortened, the fluidity is often deteriorated, and it is difficult to find a resin that serves both. The present inventor, as a result of repeated studies to solve these problems,
The present invention has been found out that, by preliminarily crosslinking a phenolic resin and blending it with a refractory aggregate, high fluidity developability and fast curing property in an amorphous refractory can be obtained.

[0004]

That is, the present invention relates to a refractory composition comprising a phenol resin having a crosslinked structure, wherein the phenol resin comprises a novolac type phenol resin and a crosslinking agent. Resin crosslinked by heating, resol type phenolic resin is crosslinked by heating or crosslinker, novolac and resol mixed phenolic resin is crosslinked by heating or crosslinker, more preferably, the acetone extraction rate of the phenolic resin Is 5 to 95%, and the particle size of the powder is 10 to
A refractory composition having a thickness of 3000 μm.

Examples of the phenolic resin used in the present invention include novolac type phenolic resin, resol type phenolic resin, benzylic ether type phenolic resin, etc. These are used alone or in combination of two or more kinds. Further, various modified phenolic resins such as rubber modified and alkylbenzene modified can also be used.

Phenols used for producing the phenolic resin used in the present invention include phenol, cresol, xylenol, catechol, resorcin, alkylphenols, bisphenols, and further when these phenols are produced. By-products are also included, and these are used alone or in combination of two or more. On the other hand, as aldehydes, formaldehyde,
Use paraformaldehyde, benzaldehyde, etc.

The catalyst for the addition condensation of phenols and aldehydes can be used properly according to the type of resin. Acid catalysts include sulfuric acid, hydrochloric acid, nitric acid,
Inorganic acid such as phosphoric acid, or paratoluene sulfonic acid,
Benzenesulfonic acid, oxalic acid, maleic acid, formic acid, acetic acid,
Any organic acid such as succinic acid can be used. In addition, metal salts such as zinc acetate, alkalis such as sodium hydroxide, potassium hydroxide, barium hydroxide and calcium hydroxide, amines such as ammonia and triethylamine are used alone or in combination of two or more.

As a method of crosslinking the phenolic resin, a method of crosslinking with heat and an acid can be typically mentioned, and among them, a method of crosslinking with heat is preferable. In the case of a novolac type phenol resin, a crosslinking agent such as hexamethylenetetramine is added and mixed in an amount of about 1 to 20% by weight with respect to the resin in accordance with a target degree of a crosslinking structure to crosslink.

The degree of the crosslinked structure of the phenolic resin referred to in the present invention was shown by using the value of the acetone extraction rate extracted by the acetone extraction test method. The acetone extraction test is a method in which uncured resin content of phenol resin is extracted using acetone as a solvent using a Soxhlet extractor. Normally, uncrosslinked phenolic resin dissolves in acetone,
As the curing progresses, it does not dissolve, and the completely crosslinked phenolic resin does not dissolve in acetone at all. That is, an acetone extraction rate of 100% means that the resin has no crosslinked structure at all, and an acetone extraction rate of 0% means a completely crosslinked phenol resin.

The phenol resin used in the present invention has a degree of crosslinking structure of 5% to 95% in terms of acetone extraction rate,
20-80% is suitable. If the acetone extraction rate is high, the curing time will be longer due to the cross-linking of the uncross-linked part in the phenol resin, but the flow developability will be improved, but the volatile content of condensed water, etc. will increase, resulting in foaming during construction. A phenomenon occurs, and as a result, the refractory structure is made porous and the corrosion resistance is reduced. On the other hand, when the acetone extraction rate is too low, the curing time is shortened because the resin is almost crosslinked, but the fluidity is deteriorated. Further, since the dispersibility in the liquid phenol resin used together, the solvent and the water is deteriorated, the physical properties of the product may be impaired.

As a heating method for thermally crosslinking the phenolic resin, there are two methods, a batch method and a continuous method.
When using a batch type heating method, a phenol resin is charged in a vat and heated. At this time, if a large amount of resin is heated at once, it is difficult for the heat to be transferred to the inside of the resin, and the degree of crosslinking becomes uneven. Further, since foaming occurs due to heating, it may be difficult to perform pulverization in the next step. Therefore, the thickness of the resin is suitably 8 cm or less, preferably 3 cm or less. When performing a continuous heating method, a phenol resin is extruded on a belt conveyor with a constant thickness and heated. Also in this case, the thickness of the resin is suitably 8 cm or less, preferably 3 cm or less for the same reason as in the batch system.

The temperature at which the phenol resin is thermally crosslinked is set according to the target degree of the crosslinked structure. When manufacturing a phenol resin having a crosslinked structure with an acetone extraction rate of 20 to 90%, the heating temperature is preferably 100 to 140 ° C. Further, in order to obtain a resol-type phenol resin having a crosslinked structure with an acetone extraction rate of 40% or less, it can be obtained by heating at 100 ° C. for 1 hour, although it depends on the molecular weight of the raw material resole. Further, in order to obtain a phenol resin having a crosslinked structure with an acetone extraction rate of 20% or less, 1
After preheating at 00-140 ° C, 150-200
By heating at 0 ° C., a phenol resin having a target degree of crosslinked structure can be obtained.

As a method of pulverizing the phenol resin having a crosslinked structure, a hammer mill, a free mill, a pulverizer or the like can be used, but it is not particularly limited. The particle size of the powder can be adjusted by the crusher used. In order to obtain a resin powder having a specific particle size, it can be easily obtained by grinding and then sieving. At this time, the feed rate of the raw material to the crusher, the rotation speed of the crusher, and the particle size obtained depend on the mesh of the screen of the crusher.

The phenolic resin obtained according to the present invention is
It can also be used in combination with pitch powder such as coal pitch and petroleum pitch. This makes it possible to shorten the slow curing time when using the pitch-based powder alone.

[0015]

The present invention will be described below with reference to examples. First, production examples of a phenol resin and a phenol resin having a crosslinked structure used in Examples will be shown. In addition, all "parts" and "%" described in the text mean "parts by weight" and "% by weight".

Production Example 1 A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 1000 parts of phenol, 707 parts of 37% formalin, and 10 parts of oxalic acid and reacted under reflux conditions for 3 hours. . Then, dehydration and dephenolation were carried out under reduced pressure until the water content and the free phenol content were lower than desired, and then the product was taken out to obtain a solid novolac type phenol resin. 1000 parts of this resin and 100 parts of hexamethylenetetramine were mixed and pulverized, and then heated at 120 ° C. for 1 hour. The obtained phenol resin having a crosslinked structure was roughly pulverized with a hammer mill and then finely pulverized with a palpelizer to obtain a phenol resin A. This phenolic resin A
Had an average particle size of 50 μm and an acetone extraction rate of 45%.

<Production Example 2> The powdered novolac type phenolic resin produced in Production Example 1 before heating is heated at 120 ° C. for 1 hour, 140 ° C. for 1 hour, 160 ° C. for 1 hour, and 180 ° C. for 2 hours. It was crosslinked. This was crushed with a crusher to obtain a phenol resin B. This phenol resin B had an average particle size of 100 μm and an acetone extraction rate of 10%.

<Production Example 3> The same procedure as in Production Example 2 was repeated except that the heating time was 120 ° C. for 2 hours, 140 ° C. for 2 hours, 160 ° C. for 2 hours, and 180 ° C. for 2 hours to form a crosslinked structure. It carried out and the phenol resin C was obtained. The phenol resin C had an average particle size of 105 μm and an acetone extraction rate of 1%.

Preparation Example 4 A reactor equipped with a stirrer, a reflux condenser and a thermometer was charged with 1000 parts of phenol, 1510 parts of 37% formalin and 230 parts of 28% ammonia water, and then gradually heated. 1 at an internal temperature of 80 ° C
The mixture was refluxed under reduced pressure for 5 minutes. After cooling to an internal temperature of 50 ° C., the mixture was allowed to stand and the separated water was removed. Then, it was dehydrated under reduced pressure at 60 ° C. to obtain a resol-type phenol resin. This resin is 100 ℃,
Heated for 1 hour. The obtained phenol resin having a crosslinked structure was roughly pulverized with a hammer mill and then finely pulverized with a palpelizer to obtain a phenol resin D. This phenol resin D has an average particle size of 30 μm and an acetone extraction rate of 40%.
Met.

<Production Example 5> The solid novolac type phenol resin and the resol type phenol resin obtained in Production Examples 1 and 4 before heating were pulverized and mixed at a weight ratio of 50:50 to obtain 10
It was heated at 0 ° C. for 90 minutes to obtain a phenol resin having a crosslinked structure. Next, after coarsely pulverizing with a hammer mill, finely pulverizing with a pulverizer to obtain a phenol resin E. This phenol resin E has an average particle size of 40 μm and an acetone extraction rate of 7
It was 0%.

<Practical Test 1> 400 particles of magnesia clinker (particle size 0.3 to 1 mm) 400 in an experimental mixer
Part, 600 parts of fine powder of magnesia clinker (particle size 0.3 mm or less), and a liquid novolac resin of diethylene glycol solvent (viscosity 4 Pa · s / 25 ° C.) as a comparative example and a phenol resin having a crosslinked structure shown in Production Examples 1 to 5 , Non-volatile content 66%), and powder resin (average particle size 32 μm) obtained by finely pulverizing the solid novolac type phenol resin of Production Example 1 with the composition shown in Table 1 at room temperature (25 ° C.) for 5 minutes to form an amorphous refractory composition. I got a thing. Then, as a hot property, the amorphous fire-resistant composition was covered with 100 g of a vinyl sheet, and the internal temperature was 1000 ° C.
Ceramic plate (200mm
(× 200 mm × 10 mm) and allowed to stand until the fluidity disappeared. As the hot characteristics, the flow distance (diameter), thickness, and adhesiveness of the taken out composition were observed, and the curing speed was observed for the presence or absence of smoke generation in the electric furnace after 10 minutes of falling.

[0022]

[Table 1] Curing speed ◯: No smoke after 10 minutes of falling ×: Smoke after 10 minutes of falling Adhesiveness ○: State where fired product and ceramic plate are adhered ×: State where fired product and ceramic plate can be easily peeled off by hand

As is clear from Table 1, the powder resin of Comparative Example 1 having no crosslinked structure has a short flow distance and a slow curing rate. In the liquid resin of Comparative Example 2, the flow distance is long and the composition is widely spread, but the curing speed is long. On the other hand, in Comparative Example 3 in which the extraction rate of acetone was low, the crosslinking reaction was almost completed, so that the curing rate was faster but the flow distance and the adhesiveness were worse than those in the above two examples. Compared to these, in Examples 1 to 4, the spreadability of the composition was improved, and the curing rate of the crosslinked portion was also increased. These phenomena are peculiar to a phenol resin having a crosslink, that is, the fluidization property is contributed by the melting phenomenon of the uncrosslinked part in the phenol resin, and the curability is contributed by the presence of the crosslinked part. ing.

<Practical test 2> 400 magnesia clinker fine particles (particle size 0.3 to 1 mm) 400 in an experimental mixer
Part, a fine powder of magnesia clinker (particle size: 0.3 mm or less), as Example 5, 5 parts of a phenol resin D having a crosslinked structure shown in Production Example 4, 5 parts of petroleum-based pitch powder and 10 parts of water. As Comparative Example 4, 10 parts of petroleum-based pitch powder and 10 parts of water were mixed at room temperature (25
(° C) for 5 minutes to obtain an amorphous refractory composition. Then, as a hot property, as in Practical Test 1, the above amorphous fire-resistant composition was covered with 100 g of a vinyl sheet, and the internal temperature was adjusted to 1000.
Ceramic plate (200
mm × 200 mm × 10 mm), and allowed to stand until the fluidity disappeared. As the hot characteristics, the flow distance (diameter), thickness, and adhesiveness of the taken out composition were observed, and the curing speed was observed for the presence or absence of smoke generation in the electric furnace after 10 minutes of falling.

[0025]

[Table 2] Curing speed ◯: No smoke after 10 minutes of falling ×: Smoke after 10 minutes of falling Adhesiveness ○: State where fired product and ceramic plate are adhered ×: State where fired product and ceramic plate can be easily peeled off by hand

From Table 2, it can be seen that in the examples in which the phenol resin having the crosslinked structure is blended, the curing rate is high while the adhesiveness is similar to that of the comparative example.

EFFECTS OF THE INVENTION By adding an appropriate amount of a phenolic resin having a crosslinked structure to a refractory skeleton, it is possible to realize an effect on fluidity development accompanying melting of an uncrosslinked part and an effect on rapid hardening of a crosslinked part. As a result, it is possible to remarkably improve the construction efficiency of the irregular-shaped refractory.

Claims (6)

[Claims] 1. An amorphous fire-resistant composition comprising a phenol resin having a crosslinked structure. 2. The amorphous refractory composition according to claim 1, wherein the phenol resin is a novolac type phenol resin mixed with a crosslinking agent and crosslinked by heating. 3. The amorphous refractory composition according to claim 1, wherein the phenol resin is a resol type phenol resin crosslinked by heating or a crosslinking agent. 4. The amorphous refractory composition according to claim 1, wherein the phenol resin is obtained by crosslinking a novolac and a resole mixed phenol resin with a heating agent or a crosslinking agent. 5. The acetone extraction ratio of the phenol resin is 5
The amorphous refractory composition according to claim 1, which is ˜95%. 6. The average particle size of the powder of the phenol resin is 1
The amorphous refractory composition according to claim 1, which has a size of 0 to 3000 μm.