JPS6034496B2 - Manufacturing method of alumina sol - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing alumina sol.

More specifically, the present invention relates to a method for producing an alumina sol that has excellent stability over time and a desired viscosity, or a method for producing an alumina sol that provides alumina powder having these properties and excellent redispersibility.

Currently, various alumina sols and the sols are made into dry powder,
There are commercially available dispersible alumina powders that are intended to be used after redispersing this material, but when these products become sol with an AI203 concentration of about 1% by weight or more, their stability over time is significantly poor, and it can last for several days. It will gel within a short time.

Furthermore, in the case of a sol with a low N203 concentration, there are disadvantages in that a large amount of medium must be transported or a large amount of medium must be evaporated during use. Furthermore, it is difficult to obtain a product with a desired viscosity with existing commercially available products, which may lead to the problem that the viscosity must be adjusted by adding an appropriate agent during use. Alumina sol is usually produced by dissolving a dispersion of alumina gel with an inorganic or organic acid.

Conventional methods for producing alumina sol: ■ A sodium aluminate aqueous solution and a water-soluble aluminum salt solution are brought to a pH of 9 to 10 and reacted in a short period of time to form an alumina gel. Or organic acid as acid group/N (molar ratio)
0.15 or more to produce a uniform sol (Special Publication No. 40-840) Acid ray/mountain (molar ratio) of mitolumina slurry
A method of dispersing alumina gel in a strong monovalent inorganic acid of 0.05 to 0.2 (British Patent No. 440194) A method of producing an alumina sol in the form of fibers having a boehmite crystal lattice by subjecting it to hydrothermal treatment in the presence of boehmite (Japanese Patent Publication No. 40-14292) has been proposed.

However, the powder for alumina sol obtained by the method (2) has poor redispersibility, it is difficult to prepare an alumina sol with an AI203 concentration of 10% by weight or less, and it has the disadvantages of poor stability over time.

Furthermore, according to Japanese Patent Publication No. 40-8409, water is added to the alumina gel produced by this method if the amount of acid added is less than 0.15 (acid group/N (mole ratio)) during the loosening operation. However, it is stated that the dispersion of alumina gel powder is merely provided without converting it into a sol form. In method (2), alumina gel obtained by a specific combination of sodium aluminate and carbon dioxide gas is solified with a strong inorganic acid, but the resulting sol is stable for only a few days if the Yama 203 concentration exceeds about 10% by weight. This has the disadvantage of

The British patent specification also states that the agglomerated boehmite alumina grains obtained by the patented method cannot be solified by monovalent weak acids such as acetic acid, formic acid, and hydrofluoric acid, and by polyhydric acids such as sulfuric acid and yakic acid. ing.

Furthermore, in the method (■), regarding the relationship between the hydrothermal treatment temperature during solization and the alumina concentration, if an AI203 concentration of about 15% by weight or more is used at a temperature of about 2500° or less, the product will be extremely poor and irreversible. This seems to be because the dispersible alumina powder obtained by this method is in the form of fibers when dispersing the dispersible alumina powder in water to prepare a liquid sol.
Even when the 03 concentration is as low as about 1% by weight or less, there is a problem that the dispersibility is poor and a sol cannot be efficiently obtained. The molar ratio of the acid radical to the alumina concentration of the strong basic acid with a dissociation constant of 0.1 or more used during hydrothermal treatment is also 0.
．． 25 or more, that is, the acid radical/AI molar ratio is 0.125 or more, but in reality, a relatively high acid concentration ratio is used.

Furthermore, when using acetic acid or formic acid, the acid line molar concentration is A.
It is possible that the I203 concentration ratio could be 4 or higher. As mentioned above, depending on conventionally known methods, high N20
There is no known method for producing an alumina sol that provides an alumina sol with excellent stability over time at three concentrations or an alumina powder with excellent redispersibility.

Furthermore, the viscosity of alumina sol produced by these conventional methods is unique to each production method, and there is no known method for producing alumina sol having a desired viscosity. Under such circumstances, the present inventors conducted intensive research in order to discover and develop a method for producing alumina sol that has excellent stability over time and alumina sol that provides alumina powder with excellent redispersibility.As a result, the present invention has been developed. I have completed the method.

That is, in the present invention, at least one of an acidic water-soluble aluminum normal salt or a soluble basic aluminum salt of a monovalent organic acid coexisting during subsequent hydrothermal treatment is treated with an alkali metal,
alkali metal or ammonia hydroxides, carbonates,
A monovalent organic acid in an amount such that the molar ratio of acid roots/mountain is 0.001 to 0.12 to the alumina gel obtained by neutralizing the alumina gel with at least one alkaline substance of bicarbonate, sulfite, and borate. Alternatively, the present invention provides a method for producing an alumina sol which, by hydrothermal treatment in the presence of a water-soluble aluminum salt of these acids, provides an alumina sol with excellent stability over time and a desired viscosity, and an alumina powder with excellent redispersibility. It is.

The present invention will be explained in detail below.

In the present invention, the acid radical of the monovalent organic acid that coexists during the hydrothermal treatment of alumina gel means that there is an acid ray that can be neutralized and titrated with an alkaline substance. For example, aluminum acetate is neutralized with caustic soda. The acetate ion produced as sodium acetate does not correspond to the acid radical in the present invention.

However, due to the use of less than the equivalent amount of caustic soda in the neutralization reaction of caustic soda, the acetate radicals remaining as partially neutralized basic aluminum acetate do not function effectively as acid radicals in the present invention. The aluminum salt used as the acidic component in carrying out the method of the present invention is a water-removalable normal aluminum salt or a soluble basic aluminum salt of a monovalent organic acid coexisting during the subsequent hydrothermal treatment. Specific examples include aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum acetate, aluminum bromide, aluminum iodide, sodium alum, potassium alum, ammonia alum, and basic ammonium acetate. Generally, it is appropriate to use readily available aluminum chloride, aluminum nitrate, aluminum acetate, etc.

On the other hand, hydroxides, carbonates, bicarbonates, sulfites, and borates of alkali metals, alkali metals, or ammonia are used as alkali-IJ substances, but generally sodium carbonate, potassium carbonate, ammonium carbonate, etc. Alkali metal or ammonia carbonates are preferred.

Incidentally, cases where insoluble salts other than alumina are produced and precipitated simultaneously with alumina in the neutralization reaction are naturally excluded.

If the reaction for producing alumina gel by neutralization reaction is carried out at a temperature higher than 10,000 ℃, the resulting gel will crystallize and become difficult to disintegrate. Implemented. The alumina gel thus produced is aged if necessary and then washed to remove impurities attached as by-products. The alumina gel after washing can be made into a dispersion liquid or a cake shape with any AI203 content by oven filtration and drying according to a conventional method.The form can be appropriately selected depending on the purpose of use, but the method of the present invention can be used. In order to carry out the process more effectively, drying the cake after the furnace solution by an appropriate means will significantly improve the scalability during the subsequent hydrothermal treatment. For this reason, alumina gel cake generally has an AI203 content of about 15 to 90.
% by weight, preferably about 55-8% by weight, and is subjected to a subsequent hydrothermal treatment. When carrying out the method of the present invention, the alumina gel obtained as described above is treated in the presence of a monovalent organic acid or a water-soluble aluminum salt of these acids in an amount such that the molar ratio of acid group/AI is 0.001 to 0.12. It is hydrothermally treated and turned into a sol. The monovalent organic acids coexisting during the hydrothermal treatment of the method of the present invention include acetic acid,
Examples include formic acid, but acetic acid is generally suitable.

Examples of the water-soluble aluminum salt of the organic acid include aluminum acetate.

The amount of acid radicals to coexist is such that the molar ratio of organic acid acid radicals/AI to AI203 in alumina gel is 0.001 to 0.1.
2, preferably in the range 0.002 to 0.10, depending on the form of the alumina sol obtained, e.g.
When producing an alumina sol with an I203 concentration and excellent stability over time, the molar ratio of acid radicals/mountains is approximately 0.
002 to 0.02, and in order to obtain a sol that has excellent disintegration properties during hydrothermal treatment and exhibits some degree of viscosity increase over time in a state where the resulting alumina sol has a high AI203 concentration, the acid The line/mountain molar ratio is about 0.02-0.
It is appropriate to control within a range of 10. If the molar ratio of acid radicals/N is about 0.0, the ratio of alumina gel to about 10
0% is dissociated, the resulting sol is clear, and there is no need for separate furnace operations for the remaining product. By appropriately selecting the acid radical/AI molar ratio within the above range, the alumina sol obtained after hydrothermal treatment will have a different viscosity even at the same mountain 203 concentration, and in general, the higher the acid radical/AI molar ratio, the higher the viscosity of the alumina sol. do. As mentioned above, monovalent organic acids, acid radicals/A
By hydrothermal treatment using the molar ratio of I, the conventional product
It is possible to obtain an alumina sol with a high AI203 concentration and any desired viscosity with excellent stability over time. However, if the acid radical/AI molar ratio is less than 0.001, it becomes extremely difficult to defrost the pig, and water Separation of the residue and sol after heat treatment is difficult, resulting in low productivity and low conversion to sol.

Furthermore, if the molar ratio of acid roots/mountains exceeds 0.12, it is thought that fibrous alumina will be formed, and even if it is decomposed during hydrothermal treatment, it will immediately gel, or even if a sol is obtained. Stability over time is significantly poor. Monovalent organic acids or water-soluble aluminum salts of these acids to be coexisting during the hydrothermal treatment of the alumina gel slurry may be added in the required amount when preparing the alumina gel slurry before the hydrothermal treatment.
In addition, in the process of obtaining raw material alumina, that is, aluminum salts of monovalent organic acids used during water treatment, such as aluminum acetate, are neutralized with less than an equivalent amount of alkaline substances to form an alumina gel in which an appropriate amount of monovalent acid groups are bonded. to generate
If this alumina gel contains a predetermined amount of residual acid radicals during the subsequent hydrothermal treatment, it can be hydrothermally treated as is or by newly adding the missing amount.

Alumina gel obtained by leaving a monovalent organic acid in it has excellent disintegration properties, and such an embodiment is preferable. The hydrothermal treatment in the method of the present invention is approximately 1200C to 300o.
o, preferably at a temperature of about 14,000 to 20,000 °C,
It is carried out for about 15 minutes to 7 hours, preferably about 3 minutes to 4 hours.

If the processing temperature is lower than about 120° C., it will take a long time to slaughter the pig, and if the processing temperature is higher than about 30,000° C., quenching equipment, high-pressure containers, etc. will be required, which is not desirable. When hydrothermal treatment is carried out under the above conditions, the alumina gel slurry gradually dissolves and changes from opalescent to opalescent and translucent, producing an alumina sol with any alumina concentration up to about 30% by weight and any viscosity. can do. The viscosity of the alumina sol obtained as described above is, for example, when the concentration of AI203 is 25
In the case of a weight% sol, the ratio is about 5 at 20oo. p (centipoise) to several 100 c. p to high viscosity ones, and AI
In the case of a sol with a 203 concentration of 10% by weight, several c. Approximately 10 ratio from extremely low viscosity called p. It is possible to produce alumina sols having any desired viscosity up to the relatively high viscosity of p, and these sols are very stable without gelation even after being left for more than three months.

As a result of X-ray diffraction and electron microscopic observation, the obtained alumina sol has a boehmite crystal lattice of approximately 0.1 to 0.0.
02 Buddha-sized plate-like objects were in a dispersed or aggregated state and were not in a fibrous state.

The alumina sol produced in this way can be used as it is as a dispersion, or it can be dried and powdered by means such as mist drying or evaporation, and then redispersed in water to form a sol. It can also be converted or used as a powder. As described in detail above, the method of the present invention can produce alumina sol that has a very low viscosity to a highly viscous sol compared to known methods, has a high AI203 concentration and has excellent stability over time, and has excellent redispersibility. It is possible to produce an alumina sol that gives the alumina powder. The alumina sol produced by the method of the present invention can be used as a heat-resistant binder in the electrical and electronic industries, ceramics, and foundry industries, as a compounding base for ointments in cosmetics and pharmaceuticals, and as a base for ointments in cosmetics and pharmaceuticals.
Aerosol products, texture improvement in the textile industry, anti-pilling, antistatic properties, emulsifiers for paints, pigments, printing inks, stabilizers, adhesion improvers, resins, surface coating agents for paper, sizing agents, catalysts in the petroleum industry It is particularly useful as a carrier.

The method of the present invention will be explained in more detail with reference to Examples below, but the method of the present invention is not limited thereto.

Example 1 AI203 10.21% by weight, acetic acid radical/AI (equivalent ratio)
The required amount of sodium carbonate is 7.9% by weight so that an amount of unreacted acetic acid radicals having the acid radical/AI (mole ratio) shown in Table 1 remains in each 100 parts by weight of the 1.0 aqueous aluminum acetate solution. The resulting alumina gel was aged for about 1 hour, washed and filtered, and the resulting cake was dried in an air bath at 100 q0 to obtain a dry gel.

The AI203 content of the dried gel obtained is shown in Table 1.

Table 1 The dried gel subsequently obtained was prepared with water into an alumina gel slurry IJ- having the AI203 concentration shown in Table 2.

Each of these alumina gel slurries was transferred into an autoclave and subjected to hydrothermal treatment at a temperature of 150 to 16,000 for 2 hours. The properties of the alumina sol obtained as a result are
Shown in the table. Table 2 *Electron microscope observation.

Example 2 AI2034.36% by weight, acetic acid radical/AI (equivalent ratio) 1
．． Add the required amount of the alkaline substance shown in Table 3 so that an amount of unreacted acetic acid radical corresponding to the acid plate/AI (molar ratio) shown in Table 3 remains in each 10 parts by weight of the aluminum acetate aqueous solution of No. 04. The resulting alumina gel was aged for about 1 hour, washed and filtered, and the resulting cake was dried in an air bath at 11,000 to obtain a dry gel.

The AI203 content of the resulting dry gel is shown in Table 3.

Table 3 The dried gel subsequently obtained was prepared with water to give an alumina gel slurry having the AI203 concentration shown in Table 4.

Each of these slurries was transferred into a glass autoclave and subjected to hydrothermal treatment at a temperature of 150 to 16,000°C. Table 4 shows the properties of the alumina sol obtained.

Table 4 Example 3 AI2034.27% by weight, CI/mountain (equivalent ratio) 1.0
19.92 parts by weight of aluminum chloride aqueous solution of 2
Approximately 300 parts by weight of 113.5 parts by weight of sodium bicarbonate
The resulting alumina gel was aged for about 1 hour, washed until no chlorine radicals were observed to flow out, and the resulting cake was heated in a furnace at 110 °C. Dry in an air bath at ℃N20372.4
% dry gel was obtained.

This dried gel was divided and dispersed in an aluminum acetate aqueous solution so as to have the mountain 203 concentration and acid-like/river (molar ratio) shown in Table 5 to prepare an alumina gel slurry. These alumina gel slurries were then transferred into a glass autoclave and subjected to hydrothermal treatment at a temperature of 150 to 16,000 for 3 hours. Table 5 shows the properties of the alumina sol obtained.

Table 5 Example 4 AI2034.07% by weight, S04/N (equivalent ratio) 1.
Add 4.26% by weight of ammonium carbonate aqueous solution as NH3 to 100 parts by weight of aluminum sulfate aqueous solution of 103.03.
5 parts by weight were gradually added to react at about 4,000 ℃, and the resulting alumina gel was aged for about 1 hour. After the sulfuric acid radicals were observed to flow out, the cake was washed until no more sulfuric acid radicals came out, and the resulting cake was then filtered in a furnace. Drying in the bus and mountain 20367.8
% dry gel was obtained.

This dried gel was divided and dispersed in a dilute acetic acid aqueous solution so that the mountain 203 concentration and acid radical/AI (molar ratio) shown in Table 6 were obtained to prepare an alumina gel slurry. Next, these alumina gel slurries were transferred into a glass autoclave and subjected to hydrothermal treatment at a temperature of 150 to 16,000 for 3 hours. The properties of the alumina sol obtained as a result are shown in the sixth column.
Shown in the table.

Table 6 Example 5 AI2034.25%, N03/AI (equivalence ratio) 1.0
Aqueous ammonium hydroxide solution containing 3.99% by weight as NH3 was added to 100 parts by weight of aluminum nitrate aqueous solution of 113.
1 part by weight was gradually added and reacted at about 3000°C, and the resulting alumina gel was aged for about 1 hour, washed until no nitrate radicals were found to flow out, and then heated in a furnace.
Dry in 2000 air bath to obtain AI20377.3
% dry gel was obtained.

This dry gel was divided to give an acid group/N (molar ratio) of 0.02.
An alumina gel slurry was prepared by adding it to an aluminum acetate solution so that the N203 concentration was as shown in Table 7. These alumina gel slurries were then transferred into a glass autoclave and heated to 150-160 CO
At a temperature of 2. Hydrothermal treatment was carried out for insect time. Table 7 shows the properties of the alumina sol obtained. Table 7 Example 6 Mountain 2034.42% by weight, acetic acid radical/AI (equivalent ratio) 1.
Approximately 30q of 121 parts by weight of a 11.9% by weight sodium carbonate aqueous solution was added to 10 parts by weight of a 0% aluminum acetate aqueous solution.
The resulting alumina gel was aged for about 1 hour, washed until no acetic acid radicals were observed to flow out, and the resulting cake was heated in a furnace and heated to 110 qo. Dry in an air bath and use N20376. A round weight percent dry gel was obtained.

This dry gel was divided and dispersed in each monovalent organic acid shown in Table 8 or an aluminum salt solution of these acids, and the N203 concentration was 10% by weight and the acid group/N (molar ratio) was 0.0.
Alumina gel slurry No. 3 was prepared. These alumina gel slurries were then transferred into a glass autoclave and subjected to hydrothermal treatment at a temperature of 150 to 160 o for 2 hours.
Table 8 shows the properties of the alumina sol obtained.

Table 8 Example 7 AI2034.36% by weight, acetic acid radical/AI (equivalent ratio) 1
．． 5.4 parts by weight of aluminum acetate aqueous solution of 04
118 parts by weight of 7% by weight potassium carbonate aqueous solution at about 40o
The alumina gel produced by gradual addition reaction at
After aging for a few hours, acetic acid ions were observed to flow out, and the cake was washed until it no longer came out.
The gel was dried in an air bath to obtain 6.3 parts by weight of a dry gel containing 9.2% by weight of AI2036.

6.3 parts by weight of this dry gel was added to 37% by weight of a 0.53% by weight formic acid solution. Add to $ parts by weight AI20310. weight%,
An alumina gel slurry having an acid radical/AI (molar ratio) of 0.05 was prepared. Next, this alumina gel slurry was transferred into a glass autoclave and subjected to hydrothermal treatment at a temperature of 150 to 1600C for 1 hour. Table 9 shows the properties of the alumina sol obtained. Table 9 Example 8 No. of Example 2 The alumina sol obtained in step 5 was mist-dried at an inlet gas temperature of 13,000 and an outlet gas temperature of 5,500 to produce alumina powder.

The properties of the alumina powder obtained as a result were as follows. Al203 content: 67. Weight % Shape: Spherical Average particle size: 20 flea These alumina powders were added to lyo water to give an AI203 concentration of 15% by weight and redispersed for 5 minutes.

As a result, the properties of the obtained alumina sol and the results obtained by redispersing commercially available dispersible alumina powder to form an alumina sol in the same manner as above are also shown in Table 1 for comparison. From Table 10, Table 1, it is clear that the product of the present invention has an excellent dispersion rate even when compared with commercially available products, and also has significantly superior sol stability over time.

Claims (1)

[Scope of Claims] 1. At least one acidic water-soluble aluminum positive salt or a soluble basic aluminum salt of a monovalent organic acid coexisting during the subsequent hydrothermal treatment is hydroxylated with an alkali metal, alkaline earth metal, or ammonia. An amount such that the molar ratio of acid radicals/Al is 0.001 to 0.12 for the alumina gel obtained by neutralizing the alumina gel with at least one alkaline substance selected from carbonates, bicarbonates, sulfites, and borates. A method for producing an alumina sol, which comprises hydrothermal treatment in the presence of a monovalent organic acid or a water-soluble aluminum salt of these acids. 2. The method according to claim 1, wherein the acidic water-soluble aluminum normal salt is aluminum chloride, aluminum nitrate, or aluminum acetate. 3. The method according to claim 1, wherein the alkaline substance is an alkali metal or an ammonia carbonate. 4 Al_2 alumina gel obtained by neutralization reaction
The method according to any one of claims 1 to 3, wherein the method is once dried and hydrothermally treated so that the O_3 content becomes about 15 to 90% by weight. 5 Alumina gel with Al_2O_3 content of about 55-80
5. The method according to claim 4, wherein the drying method is performed in such a manner that the drying method is carried out in such a manner as to increase the weight percentage. 6 The acid radical/Al molar ratio during hydrothermal treatment is 0.002~
0.10. The method according to any one of claims 1 to 5, wherein 7. A method according to any one of claims 1 to 6, wherein the hydrothermal treatment is carried out at a temperature of about 120 to 300C. 8 Claims 1 to 7 in which the monovalent organic acid is acetic acid
The method described in any one of paragraphs. 9. The method according to any one of claims 1 to 7, wherein the aluminum salt of a monovalent organic acid is aluminum acetate. 10 Neutralize aluminum acetate with an equivalent amount of an alkaline substance to obtain an alumina gel in which acetic acid radicals remain in an amount required or less than that required for subsequent hydrothermal treatment, and prepare a monovalent organic acid or an aqueous solution of these acids. 2. The method according to claim 1, wherein the hydrothermal treatment is carried out without adding or supplementing the necessary amount of aluminum salt.