JPS603027B2 - Binder for refractory materials and refractories - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new and useful binder for refractory materials and refractories, and more particularly to a water-dispersed refractory comprising a specific two-component powdered phenolic resin and a surfactant. The present invention relates to a binder for materials and a refractory made using such a specific binder in a specific ratio.

Refractories using coal tar or liquid phenolic resin as a binder are commonly used, and as the shapes of refractories become larger, methods such as press molding, vibration molding, pouring, and bulk casting have diversified. It is molded using a molding method.

However, since a binder containing a binder such as coal tar or liquid phenol resin has a high degree of hardness, it has the disadvantage of poor filling properties even when subjected to vibration molding.

In addition, if such a binder system is diluted with water or a solvent to improve the fluidity of the pot, the fluidity of the potted soil will increase, but it will only yield a refractory with high porosity and low strength, making it impractical. Not. Therefore, during vibration molding, a powdered phenolic resin, especially a powdered novolac-type phenolic resin, water and aggregate obtained using a clay material was investigated as a material with good fillability. Compared to conventional refractories, it is economically disadvantageous that high mud content occurs, resulting in a decrease in filling properties, resulting in an increase in porosity and a decrease in strength of the refractory of the final product.

The present inventors have discovered that when a binder consisting of a two-component phenolic resin and a surfactant is mixed with water in combination with fire-resistant aggregate, a material with excellent filling properties without the above-mentioned drawbacks can be obtained. It was discovered that the refractories obtained by molding ± are particularly excellent in strength, and the present invention was completed.

That is, the present invention provides a water-dispersible binder for fireproof materials comprising a two-component powdered phenolic resin and a surfactant in which the weight ratio of Hashizol-type phenolic resin to novolac-type phenolic resin is in the range of 5195 to 95/5; The present invention provides a refractory obtained by using a binder, water, and refractory aggregate in specific proportions.

As shown in Table 1 below, the binder of the present invention is difficult to aggregate and has excellent moisture stability.

It is said that the cup soil obtained by blending such a binder and water has excellent filling properties because the phenolic resin of the binder does not cause thickening due to the phenomenon of adhesion between aggregate particles during its production, that is, the mixing stage or the storage stage. Conceivable. Further, the binder of the present invention can be made of various thermosetting powder-based phenolic resins,
For example, resol-type phenolic resin, hexamethylenetetramine (hereinafter abbreviated as hexamine)-containing/borac resin, resol-type phenolic resin/novolac-type phenolic resin, and two-component powdered phenolic resin of resol-type phenolic resin/novolac-type phenolic resin. By using this method, we can improve the defect that large-sized refractories have, namely, the fact that the inner part several centimeters or more from the surface shows a marked decrease in strength compared to the surface layer due to various effects during the drying process, and the surface layer It is extremely superior in producing high-strength refractories with no difference in strength between the inside and outside.

In particular, when unfired refractories are used as they are for the internal walls of structures such as furnaces, they must have the strength to withstand large forces such as impact during work, but when the binder of the present invention is blended, this is not possible. appear more effectively. The reason why the binder of the present invention has excellent strength and can provide a refractory with no difference in strength between the inner layer and the surface layer is that the phenolic resin shown in FIG. The following conclusions can be drawn from the results of the curing time determined by the test tube method.

(The test tube method involves weighing 10 samples into a test tube, holding it at a predetermined temperature, and testing the amount of time it takes for the sample to lose its fluidity (hardening time) by shaking it with a glass rod. )
For example, small refractories (e.g., 40 x 40 x 16 embankments) obtained using powdered novolac resin containing hexamine have sufficient strength, but large refractories do not have enough strength when dry. Due to differences in heat conduction, it takes longer for the heat to rise inside the interior, which is more than a few centimeters, compared to the surface layer, and moisture stagnation occurs due to the delay in moisture evaporation, resulting in a balance between resin melt flow and curing time. It becomes difficult to do so.

For this reason, the residual water may prevent the phenolic resin from penetrating into the aggregate, or the phenolic resin may become gelatinous before it is sufficiently melted and fluidized and permeated into the aggregate, and it does not function adequately as a binder. In many cases, it is not possible to obtain a product with high strength.Also, when powdered novolak resin containing hexamine is used, the decomposition of hexamine in a water-containing system is significantly accelerated (C6N 4 days, 20 fine 2
0 → Small H30 (○), as mentioned earlier, the remaining hexamine also causes a partial curing reaction before the phenol resin sufficiently melts and flows, which further promotes a decrease in the strength of the refractory. Become. On the other hand, the binder containing the two-component phenolic resin of the present invention is cured by a condensation reaction accompanied by dehydration between a helisol resin and a novolak resin or between a resol resin, and curing is delayed in a water-containing system.

From this, it is thought that the scattering of water inside the large-sized molded product, the increase in overflow, and the sufficient melting and fluidization of the phenol resin are improved, resulting in a refractory with excellent strength.

In particular, for large molded products, it is advantageous to lengthen the gelation time and fluidity of the two-component powder phenolic resin in order to balance internal water scattering, resin melt flow, hardening time, etc. , lowering the molecular weight causes factors such as a decrease in the residual carbon of the phenolic resin binder, an increase in the porosity of the molded product, a decrease in drying and firing strength, and a decrease in fillability due to poor stability of the clay.

For this purpose, the fluidity and gelling time of the two-component powder phenol resin mixture used in the present invention are preferably 50 to 20 degrees Celsius and 100 to 40 degrees Celsius, respectively.

In the production of refractories according to the present invention, the blending ratio of the raw materials is usually 10 parts by weight (hereinafter simply referred to as parts) of the refractory aggregate, and 2 parts of the resol-type phenolic resin and the borac-type phenolic resin. 0.5 to 5 parts of component-based powdered phenolic resin,
0.1 to 2 parts of surfactant and 2 to 7 parts of water are suitable. If the blending amount of the two-component powder phenolic resin is less than 0.5 part, the strength of the refractory obtained will be insufficient, or
As the resin content increases, the porosity of the refractory increases.
It becomes bidirectional with reduced strength.

If the amount of the surfactant is less than 0.1 part, the dispersibility of the phenol resin in the clay will be poor, and if it exceeds 2 parts, the strength of the refractory will decrease.

Furthermore, if the amount of water is less than 2 parts, the phenolic resin will not be uniformly dispersed between the fire-resistant aggregates, and if it exceeds 7 parts, the drying time will be longer and the internal strength will be lowered. still,
The blending amount of each raw material may deviate from the above range depending on the use of the refractory. Furthermore, even if the two-component binder consisting of a powdered phenolic resin and a surfactant of the present invention is used by blending the powdered phenolic resin and the activator in advance, the binder may be used as a refractory aggregate when producing refractories. It may also be used in combination with water and water. In addition to this binder, additives such as pitch powder, isobutene-maleic acid copolymer, dextrin, CMC, sodium sulfate, and aluminum phosphate can be added. Next, a typical method for manufacturing a refractory bound using the binder comprising the two-component powdered phenolic resin and a surfactant of the present invention will be described.

The binder of the present invention, water, and refractory aggregate are sufficiently mixed to obtain Yaji, and then the obtained Tsuboji is put into a mold and subjected to vibration casting, and is first cast at 50 to 10 pi for about 24 to 4 hours. Drying is carried out at a low temperature, and the aggregate is moistened by moisture vapor and appropriate fluidization of the resin.

Further, the temperature is raised to 120 to 200° C. and maintained for about 24 to 4 hours to obtain an unfired refractory having high strength and low porosity after drying in both the surface layer and the internal layer. The non-condensed refractory can be further subjected to agglomeration at about 1,000 to 1,300°C in a reducing atmosphere to produce a refractory with low porosity and high firing strength. Various kinds of fire-resistant aggregates are suitable for use in the present invention, and specific examples include one or more types of koji such as alumina-based, carbon-based, silicon carbide, silica-based, magnesia-based, etc. However, silicon carbide and alumina are particularly preferred.

This component-based powder phenolic resin of the present invention can be obtained by simultaneously mixing and pulverizing a solid resol type phenol resin and a sono-type nopolak type phenol resin, or by mixing them separately pulverized. do not have.

The two-component powder phenolic resin, Hizol-type phenolic resin and Noporak-type phenolic resin, were mixed in 5/95-95.
/5, preferably in a weight ratio of 30/70 to 70/30. The weight ratio of the resol type phenolic resin and the novolac type phenolic resin is 5/9.
If it is less than 5, that is, from 0/100 to 5/95 (excluding 5/95), the strength of the refractory will decrease due to insufficient curing properties during heating. Also, if the ratio is 95/5 or more, that is, 95/5 to 100/0 (excluding 95/5), both the gelation time and fluidity of the phenol resin are short.
Insufficient internal strength. A curing agent such as hexamine is not normally added to the powdered novolac type phenolic resin used in the present invention, but it can be used in combination if necessary.

This/borac type phenolic resin is usually phenol,
1 mole of a phenolic compound such as cresol, naphthol, xylenol, etc. and 0.5 to 0.5 mole of an aldehyde compound such as formaldehyde, acetaldehyde, furfurylaldehyde, etc.
It is obtained by reacting 1.2 mol under acidic conditions with a porosity of 4 or less, and preferably has a melting point of 60 to 10 mol. In addition, powdered resol type phenolic resin is usually prepared by adding 1 mol of a phenol compound such as phenol, cresol, naphthol, or xylenol and 1.0 to 2.0 mol of an aldehyde compound such as formaldehyde, acetaldehyde, or furfurylaldehyde under alkaline conditions with a pH of 7 or more. The melting point is preferably 60 to 100°C.

Incidentally, the powdered resol type phenol resin and novolak type phenol resin may be produced by methods other than those described above.

As mentioned above, the surfactant in the present invention is effective in stabilizing the water dispersion of the phenol resin, and thereby can improve the filling properties of the cup soil.

Furthermore, the activator can reduce the amount of water added to the clay pot, and is also effective in reducing the porosity of the refractory. Such active agents are not particularly limited, and include, for example, nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkylphenol ether; higher alcohol sulfate ester salts, alkylbenzene sulfonates, and polyalkylaryl sulfonates; Anionic surfactants: Cationic surfactants such as alkyltrimethylammonium salts and high molecular weight amine derivatives are used.

Preferred are sulfonic acid salts that have residual carbon after firing and are solid under normal conditions.

In terms of shape, a powder form is preferable. Specific examples include sodium or ammonium ligninsulfonate, and sodium salt of a naphthalenesulfonic acid formalin condensate. The present invention will be specifically explained below by giving examples. Example 1 Note) Powdered resol type phenolic resin A: Melting point 670 Sieve residue 0.5% Powdered novolac type phenolic resin B:
Melting point 7 is o Sieve residue 0.3% Powder AI. 4 parts 10 powder BO. Mixture of 6 parts: fluidity 8 m, gelation time 11. The melting point, fluidity, gelation time, and sieve residue were measured according to JISK-6909.

After thoroughly mixing the above-mentioned aggregate, powdered phenolic resin, and powdered anionic surfactant in a mixer, water was added, and the cup soil, which evenly moistened the aggregate with water, was molded into a 400 x 400 x 80 Qiu Cape formwork. The mixture was placed in a mold, molded using a vibrator (G = 4), and then dried at a special low temperature of 50 to 80°C for 2 hours.
It was further dried for 150 to 18 pm to obtain a molded product. Table 1 shows the characteristics of the obtained product.

Furthermore, the water dispersion stability of the phenolic resin binder was investigated by changing the ratios of the above phenolic resin, surfactant, and water as shown in Table 2. The results are shown in Table-2. Example 2 Powder AO. 6 parts 10 powders BI. 4 parts mixture: fluidity 14
The same procedure as in Example 1 was followed for gelation time 31.

The properties of the obtained product are shown in Table 1. Example 3 The same procedure as in Example 1 was followed.

Table 1 shows the characteristics of the obtained product. Example 4 Powder AI. 0 parts 10 powders BI. Yuebu mixture: fluidity 12
5 kites Gel time 20 Brightness The same procedure as in Example 1 was followed.

Table 1 shows the characteristics of the obtained product. Comparative example 1 Powder novolac resin C (containing 5% hexamine): Melting point 7
Starvation: 0, fluidity: milk flow, gel time: 65 seconds, sieve size: 0.
5% The same procedure as in Example 1 was followed.

Table 1 shows the characteristics of the obtained product. Comparative Example 2 Liquid/borac type phenolic resin ○: Solid content 70%, viscosity (25°C) 4000 ps Other than adding the diluent ethylene glycol to xamethylenetetramine (hexamine) to the liquid novolac type phenolic resin before adding it to the mixer. , the same procedure as in Example 1 was followed.

Table 1 shows the characteristics of the obtained product. Table 1 [The surface layer is a 40 x 40 x 160 test piece cut out from the surface.

The center is 40 x 40 x 1 from a depth of 200 skins from the surface.
Cut out of 60 pine test pieces. ]Example 1
As shown in , the product of the present invention has a bending strength of 1 in the surface layer after drying.
The powdered novolac type phenolic resin of Comparative Example 1 has almost the same dry strength as the bending strength of 155k9/ground and the compressive strength of 510k9' in the center of the 60k9' ground with uneven compressive strength okQ/. When % hexamethylenetetramine is added, the bending strength of the surface layer after drying is 80 [
9/Enemy, compressive strength 210 [9/Ground, bending strength 3 in the center
The strength at the center was significantly reduced, with a compressive strength of 100k9/ground.

In addition, the product of the present invention has a porosity of 130% after drying, a specific gravity of 2.70, and a porosity of 14 after reduction and scaling of 1200 qo.
．． 2%, bulk specific gravity 2.62: A large molded product with low porosity was obtained both after drying and firing, but as shown in Comparative Example 2, in the case of liquid phenolic resin, in order to obtain fluidity that can be applied. 10% resin is added to the resin, and the apparent porosity after drying is 132%, and the bulk specific gravity is 2.50120 pi○ After the reduction scale formation, the apparent porosity is 230%, and the bulk specific gravity is 2.8. This leads to a decrease in specific gravity and an increase in apparent porosity after firing.

Table 2 Stability of water dispersion of phenol resin and binder After mixing, the mixture was held still, and after a certain period of time, it was inspected to check the dispersion state of the particles.

○: Particles have settled, but are redispersed due to soiling.

△: Agglomeration of particles is observed, but they are redispersed as secondary particles in which several particles are adhered together by the rope.

×: Completely solidified.

[Brief explanation of the drawing]

FIG. 1 is a logarithmic graph showing the relationship between curing time and temperature of phenolic resin by the test tube method. 1: Powder resol resin A/powder novolac resin B/water=
28/42/30 (weight ratio), 0: Powder resol resin A
/ water = 70/30 (weight ratio), m: powder novolak resin B containing 5% hexamine / water = 70/30 (weight ratio),
W: Powder novolac resin B containing 5% hexamine. Figure 1

Claims (1)

[Scope of Claims] 1. A water-dispersible binder for fireproof materials comprising a two-component powdered phenolic resin and a surfactant in which the weight ratio of resol type phenolic resin to novolak type phenolic resin is in the range of 5/95 to 95/5. . 2. A water-dispersible binder for a fireproof material comprising a two-component powdered phenolic resin and a surfactant in which the weight ratio of resol type phenolic resin to novolac type phenolic resin is in the range of 5/95 to 95/5, water and fire-resistant bone 0.5 to 5 parts by weight of the two-component powdered phenolic resin based on 100 parts by weight of the refractory aggregate;
A refractory obtained by using a surfactant in a proportion of 0.1 to 2 parts by weight and water in a proportion of 2 to 7 parts by weight.