JPS62158158A - Refractory composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fire-resistant composition with high explosion resistance and thermal shock resistance, and particularly to a fire-resistant composition that greatly reduces shrinkage during curing and drying and decreases in strength in intermediate temperature ranges. The present invention relates to improved refractory compositions. Moreover, it is suitable for applications that require heat resistance and corrosion resistance, and is mainly used for pouring construction as a gear staple refractory.
It can also be used for other construction works such as pressurization, spraying, pressure feeding, vibration, and coating, or for making pregeast and bricks.

[Conventional technology]

Water glass, alumina cement, various phosphates, colloidal silica, and the like are known as binders for refractories.

For these purposes, Taki Chemical Co., Ltd. (hereinafter referred to as the developer)
developed a completely new binder, basic aluminum lactate (hereinafter abbreviated as aluminum lactate) (Japanese Patent Application Laid-Open No. 57-8
No. 034).

Recently, in refractory technology, it has become common to effectively utilize ultrafine powder and dispersants to achieve low moisture content, high density, and high strength. However, this technology has the problem that the air permeability becomes extremely low due to densification, making it difficult for the moisture inside to be released, and causing steam explosion when heated and dried. It was found that the use of aluminum lactate, a new binder, has a great effect on this problem and significantly increases the explosion temperature. It is thought that this is because fine shrinkage cracks occur in the molded product of the fireproof composition using aluminum lactate, and these become pores for the release of water and gas. Furthermore, it has been revealed that these microcracks absorb and alleviate thermal strain caused by thermal quenching during high l crystallinity, thereby improving thermal shock resistance. Furthermore, the applicant previously filed a patent application after discovering that aluminum lactate evaporates lactic acid at high temperatures and only alumina remains, so it exhibits good corrosion resistance without a decrease in heat resistance. (Special application 1986
= No. 239047).

However, refractories using aluminum lactate as a binder have the drawbacks of large shrinkage during curing or drying, and a large decrease in strength in intermediate temperature ranges due to decomposition and volatilization of lactic acid. Regarding this drawback, there is research by the developer, and JP-A No. 58-63770: Intermediate temperature (500-120
A silica-containing substance or an alkaline earth metal-containing substance is added as a measure against strength reduction at 0°C.

JP-A-58-140371: Metal powder is added to increase bond strength.

JP-A-59-141457: Rehydrated alumina, alkali condensed phosphate, and nitride are added to increase bond strength.

JP-A-59-223269: As a countermeasure against fine cracks occurring during molding and drying, oxalic acid, citric acid, tartaric acid, alkali metal salts and ammonium salts thereof, and silicofluorides are added.

JP-A-60-65761: Use of polyethylene glycol or a combination of polyethylene glycol and alkanolamine or aromatic carboxylic acid is effective for preventing shrinkage and cracking during curing and drying.

JP-A-60-131857: In order to increase the bonding strength, it is good to add a dried product of the reaction between an aluminum salt and an alkali carbonate.

is disclosed. However, it cannot be said that these disclosed techniques have sufficiently solved the problems. For example, if we look at the strength in the intermediate temperature range, most of them are 2 or less of the 100°C dry strength, which still shows a large decrease in strength. In addition, as a measure to prevent shrinkage and cracking, it is thought that the most effective method is to use polyethylene glycol in combination with monoethanolamine or salicylic acid, but according to the inventor's follow-up tests, sufficient improvement in shrinkage was observed, but instead It was found that the curing strength was significantly reduced. Moreover, fluidity is lost and entrainment of air bubbles becomes noticeable.

[Problem that the invention seeks to solve]

A new binder called aluminum lactate has the wonderful advantage of significantly improving explosion resistance and thermal shock resistance, but on the other hand, it has the disadvantages of large shrinkage during curing and drying, and a significant decrease in strength in the intermediate temperature range. are doing. However, this drawback has not yet been sufficiently resolved. This invention reduces shrinkage during curing and drying without adversely affecting other properties, and greatly improves strength loss in the intermediate temperature range.

[Means for solving problems]

Use aluminum lactate and a chelating agent together. This inventor is
In the process of various studies on the use of aluminum lactate in refractories, it was discovered that the above-mentioned problems could be greatly improved by using a chelating agent in combination, leading to the present invention.

[Structure of the invention]

The fire-resistant composition of the present invention is characterized in that basic aluminum lactate is added as a binder to the refractory aggregate whose particle size has been adjusted, and a chelating agent is further used as an auxiliary agent. That is, it is a fireproof composition that essentially contains two components: aluminum lactate and a chelating agent.

As the refractory aggregate, known acidic, neutral, basic, artificial, or natural materials may be used alone or in combination of two or more.

The particle size of the aggregate is selected appropriately depending on the purpose of use, construction method, etc.

Basic aluminum lactate is an Al2O3/lactic acid (molar ratio) obtained by reacting an alumina hydrate obtained by reacting a water-soluble aluminum salt with carbonic acid or a carbonate with lactic acid.
．． 3 to 2.0 (Japanese Unexamined Patent Publication No. 57-8034). General formula Δ1 (Oll) : l-x (Lac, A
c1d) A polyelectrolyte consisting of a polynuclear complex represented by M160P, 25
It is marketed by the developer under the trade name 00.

The amount of aluminum lactate used is 0.2 to 10 parts by weight, preferably 0.3 to 6 parts by weight, based on 100 parts by weight of the refractory composition. It is difficult to notice an improvement in the explosion temperature below 0.2 parts by weight.
This is because when the amount exceeds 10 parts by weight, the strength decreases significantly.

Chelating agents are a defining feature of this invention.

This refers to metal ion sequestering agents that produce water-soluble metal chelates, and there are inorganic types (polymerized phosphates) and organic types (aminocarboxylate). Generally refers to the latter organic type. The chelating agent referred to in this invention also refers to this organic chelating agent. This is because the ligand that has the ability to coordinately bond to metal ions is bidentate or higher, such as EDTA.
(ethylenediaminetetraacetic acid), NTA (trilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid)
.

TTHA() lyethylenetetraminehexaacetic acid), )I
EDTA (hydroxyethylethylenediaminetriacetic acid), former DA (hydroxyethyliminodiacetic acid) + DH
EG (dihydroxyethylglycine) or phosphorus compound-based HEDP (hydroxyethane diphosphonic acid), NTP (trilotris methylene phosphonic acid)
For example, alkali salts and modified products thereof can be used. Among these, powdered ones are convenient to use, and water-soluble ones that are available at low cost are preferred.

In this respect, Na salts and ammonium salts of EDTA and NTA are practical. In addition, the liquid one may be used by pulverizing it with ultra-fine powder. The amount used is 0.05 to 7 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the fireproof composition.

Techniques using ultrafine powder and dispersants are also effective in this invention. The ultrafine powder is 10 μm or less, preferably 1 μm or less, and usually the finer the powder, the greater the effect. This can be made by crushing refractory aggregate, but materials such as clay, silica, alumina, titania, chromia, SiC, and C are commercially available. These may be used alone or in combination depending on the purpose.

Silicates, phosphates, carboxylates, sulfonates, and the like are well known as dispersants, but the alkali salts of each are common and are used alone or in combination.

Incidentally, polymerized alkali phosphate, which is an inorganic chelating agent, is often used as a dispersant. Furthermore, the chelating agent that characterizes this invention also functions as a dispersing agent.

Conventional dispersants are therefore not necessarily required. Flow fJ
From the viewpoint of J property and other workability, it may be desirable to use other dispersants in combination. It is also possible to use an organic glue and a water-soluble polymer together for the same purpose.

When aluminum lactate is used as the basic aggregate, the composition exhibits self-hardening properties and becomes a castable refractory. However, acidic and neutral aggregates do not exhibit self-hardening properties. When used in bricks, ramming materials, solid casting materials, etc., self-hardening is not required, but in order to use it as a castable refractory, it is necessary to use a hardening agent to make it self-hardening.

Examples of hardening agents include cements, alkaline earth metal oxides such as MgO and dolomite, ρ-alumina, alumina hydrate, chromic acid, basic aluminum sulfur, water glass, and sodium aluminate. For example, JP-A-5
8-63770), but if heat resistance is important, MgO,
It is recommended to use ρ-alumina, aluminum sulfate, high alumina cement, etc.

Note that the use of the technique disclosed by the developer is of course effective, and it is also possible to use various other known techniques for refractories, such as adding net fibers.

[Effect]

Experimental example Magnesite clinker 94 parts by weight, Titanium White 6
Parts by weight and basic aluminum lactate (A120327%
, lactic acid (61%)), a chelating agent (
The usable time, curing line change rate, and bending strength were measured by varying the amount of EDTA-3Na) added. Usable time is the time until fluidity disappears after water injection and kneading and casting becomes difficult, and the linear change rate is JIS R255.
4 (based on formwork length) and bending strength are JIS
Measured according to R2553. The results are shown in Table 1.

Table 1 * (Kgf/c) As shown in Table 1, the chelating agent improves strength loss in the intermediate temperature range and reduces shrinkage during curing.

Furthermore, it is found that the chelating agent has the effect of extending the usable time and reducing the amount of water added.

It is thought that the decrease in the amount of added water is due to the presence of dispersion and peptizing functions in the chelating agent.

The extension of usable time is due to the chelating property, which is thought to be due to the formation of a complex compound with the alkaline earth metals of MgO and CaO, which are hardening agents, and suppressing the reaction with aluminum lactate.

The reduction in curing shrinkage is probably due to the formation of chelate compounds, but the details are unknown. The effect of reducing added water may also be involved.

Regarding the improvement in strength reduction in the intermediate temperature range, the reason is not well understood. Although the cause of the decrease in strength is the thermal decomposition of the binder, aluminum lactate, the chelating agent also acts as a binder. It's a regimen and 11
This can be understood from the fact that the strength at 0°C increases.

This is also thought to be due to the formation of a chelate compound, which also thermally decomposes upon heating.

At this time, it is generally considered that the strength decreases. However, experiments yielded results that contradict this common sense.

Although it is difficult to justify the above reasons, chelating agents show useful effects such as reducing the amount of added water, extending usable time, reducing curing shrinkage, increasing strength, and improving strength loss especially in the intermediate temperature range. There was found. The amount used is 0.05 to 7 parts by weight (preferably 0.1 to 7 parts by weight) per 100 parts by weight of the fireproof composition.
3 parts by weight) is considered appropriate. The dispersion effect can be seen from an even smaller addition amount, but the improvement effect on strength reduction in the intermediate temperature range is observed from about 0.05 parts by weight, and 0.1
It becomes noticeable at about parts by weight. On the other hand, if the purpose is to extend the usable time when used at high temperatures, it is considered effective to use a considerably large amount. However, since the effect of improving strength reduction in the intermediate temperature range is not recognized and it is expensive, it is usually best to limit the amount used to about 7 parts by weight (preferably 3 parts by weight).

〔Example〕

Sintered alumina (A120399%) 1 Seawater MgO clinker (Mg095%), Calcined alumina (A120399
%, average grain 15 μm), alumina ultrafine powder (A1203
99%, average particle size 0.5μmL Silica flour (humid silica, 5i (h95%, average particle size 0.1μm)
.

Acrylic sulfonic acid dispersant (Dispersant AL Sodium phosphate dispersant (Dispersant BL Calcined MgO (Mg098%, 7
4 μm or less), basic aluminum lactate (Taxeram M160P, AIZO: 134.5%, lactic acid 49.5%
), NTA-2Na (chelating agent A), E
Casting monolithic refractories of Examples 1 to 3 and Comparative Examples 1 to 3 shown in Table 2 were prepared using DTA-2Na (chelating agent B), polyethylene glycol (degree of polymerization 6000), or salicylic acid.

For the Examples and Comparative Examples, usable time, linear change rate, bending strength, explosion temperature, thermal shock resistance, and corrosion resistance were measured. The results are shown in Table 3.

Incidentally, line change rate: according to JIS R2554. However, only curing is based on the formwork.

Bending strength: According to JIS R2553.

Explosion temperature: Cast into a size of 6 x 6 x 6 cm, temperature 20
A specimen cured for 24 hours at a temperature of 90% or higher is inserted into an electric furnace maintained at a predetermined temperature, and the lowest temperature at which an explosion phenomenon occurs is determined.

Thermal shock resistance: 1ooo℃ according to JIS R2553
Create a fired specimen. Alumina material is heated to 1400℃ - water cooling method, magnesia material is heated to 1400℃ - air cooling method. Find the number of times until breakage.

Corrosion resistance: By crucible method. Evaluate relatively based on the condition of the cut surface. The corrosive agent is steel and slag (CaO/5iOz□4.4). Maintain temperature at 1600℃ for 3 hours.

〔Effect of the invention〕

Comparative Example 1.2 using only basic aluminum lactate showed large shrinkage during curing, with intermediate temperature ranges of 600°C and 1ooo°C.
There is a significant decrease in strength. Further, in Comparative Example 3, the curing shrinkage was greatly improved by adding polyethylene glycol and salicylic acid, but an extreme decrease in curing strength and 110° C. strength was observed.

On the other hand, in all of the Examples in which a chelating agent was used, the curing shrinkage was small, and no decrease in strength was observed in the intermediate temperature range. Moreover, it is found that there is no adverse effect on explosion resistance, thermal shock resistance and corrosion resistance.

Example 3 is an example of the use of the developer's disclosed technology, in which salicylic acid was used in combination. Salicylic acid shows the effect of reducing curing shrinkage. This is presumed to be due to the entrainment of air bubbles.

Therefore, some decrease in strength is observed. However, as in Comparative Example 3, the results are not extreme. Of course, there is no decrease in strength in the intermediate temperature range. Although no dispersant was used in Example 3, the amount of water added was
It can be seen that the chelating agent has a dispersing effect, as is the case with Example 1.2.

That is, explosion resistance using basic aluminum lactate as a binder,
By using a chelating agent in combination with a fireproof composition that has excellent thermal shock resistance and corrosion resistance, it is possible to impart excellent volume stability and stable strength in each temperature range.

This has made it possible to create a fire-resistant composition with even higher performance.

Patent applicant: Japan Tokushu Furozai Co., Ltd. Representative opinion, Minoru Mizoguchi *(Kgf/csA)

Claims (1)

[Claims] A fireproof composition comprising basic aluminum lactate and a chelating agent as essential components.