JPS6222815A - Liquid phenolic resin for refractory - Google Patents

Abstract

PURPOSE:The titled quality resin which does not undergo cracking nor swelling irrespective of the influences of seasonal factors, compositions, drying conditions, etc., containing a specified amount of water. CONSTITUTION:The water content of a novolak liquid phenolic resin obtained by reacting a phenol with an aldehyde in the presence of a catalyst such as oxalic acid in a solvent which can dissolve a novolak resin [e.g., (di)ethylene glycol] is adjusted to 2-10wt% by the addition of, if necessary, water. In this way, the titled resin useful for the production of refractories for steel manufacturing, such as unburned magnesia carbon brick or unburned alumina carbon brick.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a liquid phenolic resin for refractories used in manufacturing refractories for steel manufacturing such as unfired magnesia carbon bricks and unfired alumina carbon bricks. It is something.

[Prior art]

In recent years, unfired graphite-containing refractories have been in the spotlight as steelmaking refractories used in converters, electric furnaces, ladles, pig iron mixers, etc.
At the same time, the field of use of phenolic resins, which are considered to be optimal as binders, has expanded. As the phenolic resin used as a binder for unfired graphite-containing refractory bricks, novolac type and/or resol type liquid and/or powder resins are used alone or in combination.

To give a typical example, in the case of a novolak type phenolic resin, a powder resin containing hexamethylenetetramine (hereinafter referred to as hexamine) is used together with a wetting agent such as methanol or ethylene glycol, or a resol. It is used in combination with mold liquid phenolic resin. In addition, a liquid resin prepared by dissolving a novolac type phenol resin in advance in a solvent such as ethylene glycol is used by adding hexamine when crosstalk occurs.

On the other hand, in the case of resol-type phenolic resins, water-based liquid resins or solvent-based liquid resins containing solvents such as ethylene glycol are used alone, or these liquid resins are combined with powdered phenolic resins. It is used.

As mentioned above, various types of phenolic resins are used as binders and materials for refractory bricks containing unfired graphite, but among them, novolac-type liquid resins are the mainstream because the resin itself does not change over time, has little odor, and is easy to handle. It has become.

Conventionally, the novolac type liquid resin used as a binder for refractory bricks containing unfired graphite is said to be good if its water content is as low as possible because the aggregate dislikes water. 1% or less was used. However, when such a binder is used, cracks and blisters may occur on the brick surface due to seasonal factors, compound composition, drying conditions, etc., resulting in a significant drop in commercial value. Conditions that tend to cause cracks and blisters include winter, the composition of the compound containing metal powder or recycled aggregate (recycled from used bricks), and drying conditions such as the rate of temperature rise. is too fast or too slow, etc.

[Object of the Invention] The present inventors have conducted extensive studies on countermeasures for the poor appearance that occurs when a novolac-type liquid resin is used as a binder for unfired graphite-containing bricks, and as a result, they have arrived at the present invention.

[Structure of the invention]

The present invention provides a novolac type liquid phenolic resin for refractories with a moisture content of 2 to 10% by weight, preferably 2% by weight.
-6% by weight of a novolac type liquid phenolic resin. Note that the moisture content defined in the present invention is a value measured by the Karl Fischer method.

In the present invention, by increasing the water content in the phenolic resin compared to conventional ones, the appearance of the large-sized product can be improved without being affected by seasonal factors, compound composition, drying conditions, etc. Although the reason for this is not clear, it is thought that the appropriate amount of water contained in the resin suppresses changes in the wettability of the resin and aggregate due to the above conditions.

The phenols used to produce the novolac type liquid resin of the present invention include phenol, cresol, xylenol, ethylphenol, propylphenol, catechol, resorcinol, hydroquinone, and bisphenol A. It also includes by-products from the production of products, and these can be used alone or in combination of two or more.

On the other hand, as the aldehyde, formaldehyde, zuraformaldehyde, etc. are used.

Further, as a catalyst, an acidic substance such as oxalic acid, hydrochloric acid, sulfuric acid, or zinc acetate is used.

Further, as the solvent, glycols such as ethylene glycol and diethylene glycol are preferred, but various other solvents that dissolve the novolak resin can also be used alone or in combination of two or more.

In addition, a small amount of synthetic resins and/or natural polymers such as epixy resin, melamine resin, urea resin, polyvinyl alcohol, starch, dextrin, lignin, gum arabic, hydroxymethyl cellulose, etc. are blended into a part of the composition. Also good.

In the present invention, the amount of water contained in the phenolic resin is 2-10% by weight, preferably 2-6% by weight. When the amount of water is less than 2% by weight, the effect of preventing poor appearance is poor. On the other hand, if the weight is more than 10%, the wetting between the resin and the aggregate becomes poor, and the clay after kneading tends to become loose.
Fillability during molding becomes poor. Further, since novolac resin is difficult to dissolve in water, if it contains 10 weight or more of water, the resin may become cloudy and undergo phase separation, making it impossible to obtain a homogeneous solution.

〔Effect of the invention〕

When unfired gold graphite refractory bricks are manufactured using the liquid phenolic resin for refractories of the present invention, seasonal factors, compound composition,
A high-quality product without cracks or blisters can be obtained almost unaffected by drying conditions.

Good quality products without cracks or blisters are obtained, especially in winter, when the formulation contains metal powder or recycled aggregate, or when the drying rate is fast.

〔Example〕

Hereinafter, the present invention will be specifically explained using examples. All "parts" and "chi" in the text indicate "parts by weight" and "% by weight."

Example 1 2000 parts of phenol, 1035 parts of 37 thiformin and 20 parts of oxalic acid were charged into a reaction apparatus equipped with a stirrer, a reflux condenser and a thermometer, and the mixture was reacted at 98 to 103°C for 3 hours. Next, dehydration was carried out under reduced pressure of 60 to 80 mHf until the maximum liquid temperature reached 120°C. When the liquid temperature reached 120° C., the pressure was returned to normal, and 400 parts of ethylene glycol and 80 parts of tap water were added and mixed to obtain 2500 parts of a liquid phenolic resin for refractories. This resin had a viscosity of 75 pis/25° C. and a water content of 3.5 pis.

Example 2 Into the same reactor as in Example 1, 2000 parts of phenol and 3
1294 parts of 7% formalin and 6 parts of 35% hydrochloric acid were charged and reacted at 98 to 103°C for 3 hours. Then 60~
Dehydration was carried out under reduced pressure of 80 mHt until the maximum liquid temperature reached 120°C. When the liquid temperature reached 120° C., the pressure was returned to normal, and 700 parts of ethylene glycol, 700 parts of diethylene glycol, and 130 parts of tap water were added and mixed to obtain 3,550 parts of a liquid phenol resin for refractories. This resin had a viscosity of 78 voids/25° C. and a water content of 4.0 inches.

Comparative Example 1 After reaction and vacuum dehydration were performed under the same conditions as in Example 1, 650 parts of ethylene glycol was added and mixed to obtain 2,670 parts of liquid phenol resin. This resin had a viscosity of 73 voids/25° C. and a water content of 0.3%.

Comparative Example 2 After reaction and vacuum dehydration under the same conditions as in Example 2, 400 parts of ethylene glycol and 40 parts of diethylene glycol were added.
0 parts and 330 parts of tap water were added and mixed to obtain 3160 parts of liquid phenol resin. This resin has a viscosity of 701 is/2
The temperature was 5°C and the moisture content was 10.7%.

<Practical test> This test shows that when using conventional resin with low water content,
Conditions that tend to cause cracks and blisters in molded bricks, i.e.
Testing was carried out under the following conditions: mixing and storing the mixture at low temperatures, mixing metal powder, and increasing the temperature at a high rate during drying.

In an experimental mixer, 2500 parts of magnesia clinker (a mixture of 70% coarse grains with a particle size of 1 to 3 mm and 30% fine grains with a particle size of 0.3 van or less), 500 parts of cylindrical graphite, and 150 parts of metal aluminum powder were added. , the above liquid phenolic resin 105
and 10.5 parts of hexamine were added and kneaded at 10° C. for 30 minutes to obtain a clay. Using a part of this clay, the state of the clay immediately after cross-contact and after time (storage conditions: 10℃, sealed)
The test was conducted by feeling it in the hand. On the other hand, the remaining buried soil was stored under sealed conditions at 10℃ after cross-contact, and after one day, it was heated to 100℃ in a 30X30X120+w+ mold.
It was molded at 0 kf/cJt, then dried from room temperature to 170°C for 2 hours, and further dried at 170°C for 8 hours to create a test piece of an unfired graphite-containing refractory. The appearance, bulk specific gravity, porosity, and bending strength of this test piece were measured.

The results are shown in Table-1.

As is clear from Table 1, when the liquid phenolic resins for refractories of Examples 1 and 2 were used, the condition of the clay was good immediately after cross-contact and after aging. No cracks or bulges were observed in the appearance of the pieces, and the bulk specific gravity and bending strength values were also good. On the other hand, when the liquid phenol resin of Comparative Example 1 was used, the condition of the clay was good, but
Cracks and blisters appeared on the surface of the test piece after drying, and the physical properties also showed low values. Furthermore, when the liquid phenol resin of Comparative Example 2 was used, the clay changed significantly over time, the appearance was somewhat poor, and the physical properties were also significantly reduced.

Claims (1)

[Claims] Amount of novolak used in refractories: A novolak-type liquid phenol resin for refractories, characterized in that the water content is 2 to 10% by weight.