JPH0696451B2 - Method for producing antimony pentoxide sol - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an antimony pentoxide sol. More specifically, sodium antimonate and an inorganic acid are reacted to form an antimony pentoxide gel, and the gel is then separated, washed, and peptized to obtain an antimony pentoxide sol. After washing with an aqueous solution of inorganic acid, and further with a mixed solution of hydrophilic organic solvent such as alcohol and water, disperse the obtained antimony pentoxide wet cake in water and add an organic base or phosphoric acid to peptize. And a method for producing an antimony pentoxide sol having a low sodium content.

Antimony pentoxide sol is used as a flame retardant aid for plastics, fibers, microfillers for surface treatment agents for plastics and glass, or inorganic ion exchangers for the purpose of removing metal ions, raw materials for catalysts and pigments, etc. However, in recent years, applications other than flame-retardant applications have been increasing along with the progress of technology using inorganic colloids.

(Prior Art) As a method for producing this antimony pentoxide sol, there are the following methods.

(1) Method of deionizing alkali salt of antimonic acid with an ion-exchange resin (Japanese Patent Publication No. 57-11848, US Pat. No. 4)
No. 110247).

(2) A method of oxidizing antimony trioxide with hydrogen peroxide at high temperature (Japanese Patent Publication No. 53-20479, Japanese Patent Publication No. 52-21298).
The antimony pentoxide sol having a pH of 1 to 4 obtained by JP-A-52-123997) is stabilized with an organic base.

(3) A method of reacting an alkali antimonate with an inorganic acid and then peptizing with an organic base or phosphoric acid (Japanese Patent Application Laid-Open No. 60-41536, Japanese Patent Application No. 60-70719), etc., filed by the present inventors. To be

(Problems to be Solved by the Invention) Even if a large amount of sodium ion is present in the antimony pentoxide colloid, it does not inhibit flame retardancy when used as a flame retardant aid, but the presence of sodium ion Since it reduces the ion exchange capacity, it is not suitable for use as an additive (metal passivator) to prevent the activity deterioration of the fluid catalytic cracking catalyst for heavy petroleum fractions, so the content of alkali ions is low. A highly stable antimony pentoxide sol has been desired.

Since the antimony pentoxide sol obtained by the method of deionizing the alkali salt of antimonic acid, which is the above-mentioned method (1) of the prior art, has a shape close to a sphere, it has good dispersibility. Although it has the characteristic that the concentration can be increased, this method reduces the concentration of antimony pentoxide to 10%.
As described above, there are drawbacks such that it is difficult to perform ion exchange, and the operation is complicated because of the separation and regeneration operations of the ion exchange resin. Furthermore, this method cannot reduce the alkali content in the colloid. According to the method (2) of oxidizing antimony trioxide with hydrogen peroxide at high temperature, a sol of 30% or more can be directly obtained as antimony pentoxide, but if it is 30% or more, the viscosity becomes high. Although the colloidal particles obtained by this method do not contain alkali ions, they have the drawback that they have a poor particle shape and poor dispersibility, so that they settle and separate upon standing.

After reacting the sodium antimonate of (3) with an inorganic acid,
The obtained antimony pentoxide gel is washed with water, and then the gel is dispersed in water and peptized with an organic base or phosphoric acid. The method is to directly obtain a high-concentration sol with good particle shape and good dispersibility and stability. However, with this method, the sodium ion content cannot be Na ₂ O and the molar ratio of Na ₂ O / Sb ₂ O ₅ cannot be 0.2 or less. The antimony pentoxide gel obtained by the reaction of sodium antimonate and an inorganic acid contains a large amount of sodium ions in its structure, and the content of the sodium ions is, in general, a molar ratio of Na ₂ O / Sb ₂ O ₅ is 0.2 ~
It is 0.6.

The fact that sodium ions in the antimony pentoxide gel can be reduced by acid washing is described in JP-A-56-59851 regarding a flame retardant composition comprising a mixture of antimony pentoxide and sodium antimonate. However, after the acid washing, if the remaining acid is removed by washing with water, not only the washing becomes extremely difficult because a part of the antimony pentoxide gel is peptized into a sol during washing, The loss due to gel washout during washing also increases. Furthermore, this gel is less likely to be deflocculated, and the obtained sol has a bad particle shape, a large particle size distribution, and poor sol stability.

It is an object of the present invention to provide a method for producing an antimony pentoxide sol, which improves the above-mentioned conventional drawbacks, has a low sodium ion content, has a good particle shape, and is excellent in stability.

(Means for Solving Problems) The inventors of the present invention have conducted extensive studies on a method for producing an antimony pentoxide sol that meets the above-mentioned object, and as a result, have found that antimony pentoxide gel produced by the reaction of sodium antimonate and an inorganic acid is produced. The above problems are solved by separating and washing with an aqueous solution of an inorganic acid to reduce sodium ions, washing with a mixed solution of a hydrophilic organic solvent such as alcohol and acetone, and then peptizing. The present invention has been completed by finding out that it is possible.

That is, the present invention uses sodium antimonate at a stoichiometric ratio of 0.5
~ 5-fold amount of monovalent or divalent inorganic acid is reacted to form an antimony pentoxide gel, the gel is separated, washed with an aqueous solution of monovalent or divalent inorganic acid, and further hydrophilic organic solvent After washing with water, the organic base is added thereto in a stoichiometric ratio of 0.01 to 1 with respect to Sb ₂ O ₅ , or phosphoric acid is added to P ₂ O ₅ / Sb ₂ O ₅ Of the antimony pentoxide sol having a sodium content of 0.001 to 0.2 in terms of a Na ₂ O / Sb ₂ O ₅ molar ratio, which is characterized in that the peptization is performed by adding so that the weight% thereof is 0.2 to 5%.

The starting material of the present invention, sodium antimonate, has the general formula
Na ₂ O.Sb ₂ O ₅ .xH ₂ O (x = 0 to 6), especially sodium antimonate hydrate Na ₂ O.Sb ₂ O _{5
· 6H 2 O (Sb 2 O} 5 64% ~65 wt%, Na ₂ O12~13 wt%, H ₂ O
23 to 24% by weight) is preferred.

The acid that can be used in the process for producing an antimony pentoxide gel by the reaction of sodium antimonate and an inorganic acid of the present invention is a monovalent or divalent inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid or sulfamic acid. With phosphoric acid, antimony pentoxide gel cannot be obtained because it becomes an aqueous solution of sodium antimonate phosphate. In addition, organic acids such as formic acid and oxalic acid cannot form the desired antimony pentoxide gel.

In the reaction of the sodium antimonate of the present invention with the above acid, the concentration of sodium antimonate can be 2 to 40% by weight as anhydrous antimony pentoxide (Sb ₂ O ₅ ) in the reaction solution. When it is 2% by weight or less, it is not economical because the amount of antimony pentoxide gel produced becomes small, and when it is 40% by weight or more, the solid content in the reaction solution becomes 60% or more, which is not preferable because the reaction becomes nonuniform. Preferably, anhydrous antimony pentoxide (Sb
It is 6 to 35% by weight as ₂ O ₅ ).

In the reaction between the sodium antimonate of the present invention and the above-mentioned acid, the concentration of the acid is the stoichiometric ratio of acid / sodium antimonate.
It is in the range of 0.5 to 5, preferably 1 to 3. If the stoichiometric ratio is 0.5 or less, the desired antimony pentoxide gel cannot be obtained even if the reaction temperature or the concentration of sodium antimonate is increased. On the other hand, if the stoichiometric ratio is 5 or more, the produced antimony pentoxide gel is partially decomposed when washed and the sol easily flows out into the filtrate, resulting in poor productivity. Here, the stoichiometric ratio is [HX] / 2 [Na ₂ O ・ Sb in the case of monovalent acid.
₂ O ₅ · xH ₂ O] ratio (the number in [] is the number of moles), and in the case of a divalent acid, it is the [HX ′] / [M ₂ O · Sb ₂ O ₅ · xH ₂ O] ratio.

The reaction temperature of the sodium antimonate of the present invention and the above acid is from room temperature to 100 ° C, and the reaction time can be 0.5 hours or more. In order to obtain an antimony pentoxide sol having a good particle size, the reaction temperature is preferably 50 ° C. or less and the reaction time is preferably 10 hours or less. The antimony pentoxide gel slurry obtained by the reaction can be easily separated by various methods such as pressure filtration, suction filtration and centrifugal filtration.

The X-ray diffraction pattern of the antimony pentoxide gel obtained by the reaction is the same as that of hydrated antimony pentoxide (Sb ₂ O ₅ .4H ₂ O). Remaining ions are observed.
The amount is generally 0.2 to 0.6 of Na ₂ O / Sb ₂ O ₅ in molar ratio. This antimony pentoxide hydrate is an ion exchanger, and can release or take in sodium ions without causing structural changes. Therefore, the sodium ion in antimony pentoxide cannot be reduced only by washing the antimony pentoxide gel obtained by the reaction with water, but the sodium ion can be reduced by washing with an acid.

Acids that can be used for washing are monovalent or divalent inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid and sulfamic acid, and hydrochloric acid is particularly preferable. The acid concentration in washing can be 1% or more. 1
If it is less than%, the sodium ion cannot be reduced sufficiently. During this acid washing, the antimony pentoxide gel does not peptize and the washing is easy.

After acid cleaning, it is necessary to remove the acid remaining in the antimony pentoxide wet cake, but as described at the beginning, if the washing is performed only with water, the antimony pentoxide gel will partially disappear as the acid ions decrease during the washing. Peptization causes clogging of the filter paper or filter cloth, making filtration impossible.

It is a feature of the present invention that, by using an aqueous solution of a hydrophilic organic solvent at the time of this washing, partial decomposition glue of the antimony pentoxide gel at the time of washing can be suppressed and the washing can be easily performed. Of course, it is possible to use only a hydrophilic organic solvent, but an aqueous solution is preferable in terms of cost and safety. Examples of the hydrophilic organic solvent include alcohols such as methanol, ethanol, isopropanol, n-propanol and t-butanol, ketones such as acetone and methyl ethyl ketone,
Ether solvents such as dioxane and tetrahydrofuran, dimethylformamide and the like can be used, but those having a lower boiling point than water are preferable.

The hydrophilic organic solvent used for washing remains in the wet cake, but the solvent with a low boiling point evaporates during peptization,
In the obtained sol, a small amount remains in the sol or hardly remains.

The concentration of the hydrophilic organic solvent is preferably 5% to 50%. If it is less than 5%, the effect of suppressing peptization is small and washing becomes impossible. By acid washing and washing with an aqueous solution of a hydrophilic organic solvent, the amount of sodium ions in antimony pentoxide gel was changed to Na ₂ O and Sb ₂ O was added.
_The stoichiometric ratio of ₅ can be 0.2 or less and 0.001 or less.

This antimony pentoxide gel wet cake was dispersed in water and then deflocculated under the conditions described below to give a sodium content of Na ₂ O of 0.2 in a stoichiometric ratio to Sb ₂ O ₅ .
~ 0.001 antimony pentoxide sol can be obtained.

Incidentally, this antimony pentoxide gel cannot be deflocculated under the conditions described below when it is made into a dry gel.

Examples of bases that can be used for peptization of the antimony pentoxide gel of the present invention include monoethanolamine, diethanolamine, triethanolamine, n-propylamine, N
-Aminoethylethanolamine and other amines, monomethyltriethanolammonium hydroxide, tetraethanolammonium hydroxide and the like
Examples thereof include organic bases such as quaternary ammonium hydroxide and guanidine hydroxide. Further, usable phosphoric acid is orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, triphosphoric acid, tetraphosphoric acid and the like, which are easily available as commercial industrial products. Of the phosphoric acids, orthophosphoric acid is most preferred.

In the present invention, the peptization concentration is from room temperature to 15 in the case of an organic base.
0 ℃, 60-160 ℃ in the case of phosphoric acid, and deflocculation by autoclave is not economical.
100 ° C is preferred. The time for peptization varies depending on the types of organic base and phosphoric acid, the amount used, and the peptization temperature, but it is 0.5-1
It's 0 hours.

In the present invention, the amount of organic base required for peptization is 0.01 to 1 in terms of stoichiometric ratio of organic base / Sb ₂ O ₅ , and preferably 0.04.
~ 0.5. Here, the stoichiometric ratio means [organic base] / 2 [Sb ₂ O ₅ ] (in [] is the number of moles) in the case of a monovalent organic base, and [organic base in the case of a divalent organic base. Base] / [Sb ₂ O
₅ ] Ratio.

When the stoichiometric ratio is 0.01 or less, the peptization is not sufficiently performed even if the peptization temperature is increased. On the other hand, if the stoichiometric ratio is 1 or more, the amount of ions in the sol will be too large and the stability of the sol will be reduced, such being undesirable.

When the peptizer is phosphoric acid, P ₂ O _{5 is used} as P ₂ O ₅ / Sb ₂ O ₅
Is 0.2 to 5%, preferably 0.5 to 2%. When it is 5 wt% or more, the peptization occurs, but the particle size of the antimony pentoxide colloid is small and the amount of phosphoric acid is large, so the viscosity of the sol is high and the compatibility with resin emulsions, water-soluble polymer compounds, acids, alkalis, etc. It becomes bad and is not preferable. If it is less than 0.2%, the deflocculation is not sufficiently performed even if the deflocculation temperature is increased.

The peptization concentration in the present invention can be _{2 to} 55% by weight as anhydrous antimony pentoxide (Sb ₂ O ₅ ) in the case of organic base peptization, and in the case of low peptization concentration, peptization sol The concentration can be easily increased by an evaporation method, an ultrafiltration method, a reverse osmosis method, or the like. In the case of peptization with phosphoric acid, the peptization concentration is 2 to 30.
Weight percent is possible. Also in this case, it is possible to concentrate by an evaporation method, an ultrafiltration method, a reverse osmosis method or the like.

The pH of the antimony pentoxide sol obtained by deflocculating phosphoric acid is 1 to 4
However, by adding a base such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, triethanolamine, monoethanolamine, and quaternary ammonium hydroxide to this sol, the pH is adjusted to 4-11. Then, this can be concentrated to obtain a sol of 30-60 wt% as anhydrous antimony pentoxide (Sb ₂ O ₅ ).

The particle size of the antimony pentoxide colloid obtained by the method of the present invention is 5 to 50 mμ as observed by an electron microscope, the particle shape is almost spherical, the particle size distribution is small, and the sodium ion content in the antimony pentoxide sol is very small. There is a feature that can be reduced.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples. In the following examples and comparative examples,% is% by weight, and sodium antimonate used was Sb.
_{2 O 5 64%, Na 2} O12.5%, those of H ₂ O23.5% of the composition.

Example 1 263 g of sodium antimonate was dispersed in 1200 g of water, and 257 g of 35% hydrochloric acid was added to this while stirring, and the mixture was heated to 40 ° C. and reacted for 3 hours. The concentration of antimony pentoxide in the reaction solution was 9.9% as Sb ₂ O ₅ , and the stoichiometric ratio of hydrochloric acid / sodium antimonate was 2.33. Next, the antimony pentoxide gel slurry produced by the reaction was suction-filtered and poured with 1500 g of a 3.5% aqueous hydrochloric acid solution to remove sodium ions in the antimony pentoxide. Then, a mixed solution of 3600 g of water and 1800 g of methanol was poured and washed. The obtained antimony pentoxide gel wet cake 288 g was Sb ₂ O ₅ 58.4%, Na ₂ O0.25
%, And the Na ₂ O / Sb ₂ O ₅ molar ratio was 0.02. The filterability during washing was good.

The above antimony pentoxide gel wet cake was dispersed in 1025 g of water, and after adding 1.5 g of 85% phosphoric acid thereto, the mixture was heated to 80 ° C. and deflocculated for 2 hours. The peptization rate was 99%. The obtained sol has a specific gravity of 1.132, pH of 2.20, a viscosity of 2.3 cp, and Sb ₂ O ₅ 1
_{2.8%, P 2 O 5 0.07} %, Na 2 O0.055%, Cl160ppm, particle size 20
-40 mμ, phosphoric acid / Sb ₂ O ₅ stoichiometric ratio was 0.019, and methanol content was very low. The particle shape was almost spherical.

Example 2 530 g of sodium antimonate was dispersed in 648 g of water, and then 515 g of 35% hydrochloric acid was added with stirring, and the mixture was heated to 35 ° C. and reacted for 5 hours. The concentration of antimony pentoxide in the reaction solution is 20% as Sb ₂ O ₅ , and the stoichiometric ratio of hydrochloric acid / sodium antimonate is 2.32. Next, the antimony pentoxide gel slurry produced by the reaction was suction filtered, and 3600 g of a 3.5% hydrochloric acid aqueous solution was dividedly injected to remove sodium ions in the antimony pentoxide. Then 6000 g of water and 1200 g of ethanol
The mixed solution of (1) was poured separately and washed. The cleanability was good.

The obtained antimony pentoxide gel wet cake 545 g,
_{Sb 2 O 5 62.2%, Na} 2 O0.14%, was Na ₂ O / Sb ₂ O ₅ molar ratio 0.01.

The above antimony pentoxide gel wet cake was dispersed in 1125 g of water, 27 g of triethanolamine was added thereto, and the mixture was heated to 75 ° C. and deflocculated for 3 hours. The presence of unpeptized material was not recognized. The obtained sol has a specific gravity of 1.224, p
H5.25, viscosity _{2.2cp, Sb 2 O 5 20.6%} , Na 2 O0.044%, amine 1.59%, amine / Sb ₂ O ₅ stoichiometric ratio was 0.086.
The particle size was 10 to 30 mμ, and the particle shape was almost spherical. The stability of the sol was also good, and even if it was stored at 50 ° C for 1 month, the above was not observed.

The obtained sol was diluted to a Sb ₂ O ₅ concentration of 14% and passed through a column packed with a cation exchange resin (Amberlite 120B) to remove triethanolamine. The obtained sol has a specific gravity of 1.140, pH 2.25, viscosity of 2.6 cp, Sb ₂ O ₅ 14.0%, Cl ₂
It was 00 ppm.

By spray-drying this sol, antimony pentoxide powder having an average diameter of 2 μ was obtained. Since this antimony pentoxide powder contains almost no sodium and has high reactivity, it is effective as a raw material for pigments and the like.

Example 3 800 g of sodium antimonate was dispersed in 550 g of water, and 400 g of 35% hydrochloric acid was added to this while stirring, and the mixture was heated to 30 ° C. and reacted for 4 hours. The concentration of antimony pentoxide in the reaction solution was 29.3% as Sb ₂ O ₅ , and the stoichiometric ratio of hydrochloric acid / sodium antimonate was 1.19. Then, the antimony pentoxide gel slurry produced by the reaction was suction-filtered, and divided injection was performed with 4000 g of a 7.0% hydrochloric acid aqueous solution to remove sodium ions in the antimony pentoxide. Then 6400 g of water and 1600 g of acetone
The mixed solution of (1) was poured separately and washed. The cleanability was good.

800 g of the obtained antimony pentoxide gel wet cake,
_{Sb 2 O 5 64%, Na} 2 O0.61%, was Na ₂ O / Sb ₂ O ₅ molar ratio of 0.05.

The above antimony pentoxide gel wet cake was dispersed in 930 g of water, and 26 g of triethanolamine was added thereto, and then 8
The mixture was heated to 5 ° C and peptized for 5 hours. No peptized material was observed.

The obtained sol has a specific gravity of 1.380, pH 4.96, viscosity of 3.5 cp, and Sb.
_{2 O 5 29.4%, Na 2} O0.28%, triethanolamine 1.48
%, Cl 260 ppm, particle size 10-40 mμ, triethanolamine / Sb ₂ O ₅ stoichiometry was 0.055. The particle shape was almost spherical. Almost no acetone was contained in the sol.

Example 4 800 g of sodium antimonate was dispersed in 584 g of water, and then 680 g of 60% nitric acid was added thereto with stirring, and the mixture was heated to 35 ° C. and reacted for 6 hours. The concentration of antimony pentoxide in the reaction solution was 25.0% as Sb ₂ O ₅ , and the stoichiometric ratio of nitric acid / sodium antimonate was 2.03. Next, the antimony pentoxide gel slurry produced by the reaction was suction-filtered, and divided injection was performed with 5000 g of a 10% nitric acid aqueous solution to remove sodium ions in the antimony pentoxide. Then, a mixed solution of 8000 g of water and 800 g of acetone was separately poured and washed. The cleanability was good. The obtained antimony pentoxide gel wet cake 81
0g _{is, Sb 2 O 5 63.7%,} Na 2 O0.82%, Na 2 O / Sb 2 O 5 molar ratio of 0.
It was 067.

The above antimony pentoxide gel wet cake was dispersed in 1760 g of water, 10 g of 85% phosphoric acid was added thereto, and the mixture was heated to 85 ° C. and deflocculated for 3 hours. The peptization rate was 98%. The obtained sol has a specific gravity of 1.220, pH 2.24, viscosity of 2.4 cp, and Sb ₂ O ₅ 2
_{0.0%, P 2 O 5 0.24} %, Na 2 O0.026%, HNO 3 210ppm, phosphate /
The Sb ₂ O ₅ stoichiometry was 0.042.

Comparative Example 1 Sodium antimonate (530 g) was dispersed in water (1200 g), and then 35% hydrochloric acid (514 g) was added with stirring, and the mixture was heated to 40 ° C. and reacted for 3 hours. The concentration of antimony pentoxide in the reaction solution is 15.3% as Sb ₂ O ₅ , and the stoichiometric ratio of hydrochloric acid / sodium antimonate is 2.33. Then, the antimony pentoxide gel chiller produced by the reaction was suction-filtered, 3500 g of 3.5% hydrochloric acid aqueous solution was injected, the sodium ion in antimony pentoxide was removed, and further 4000 g of water was added for washing.
The washing time was very long due to the partial deflocculation of the antimony pentoxide gel during washing.

524 g of the obtained antimony pentoxide gel wet cake,
_{Sb 2 O 5 64.7%, Na} 2 O0.52%, Na 2 O / Sb 2 O 5 molar ratio 0.04, Cl
It was 2400 ppm.

The above antimony pentoxide gel wet cake was dispersed in 1150 g of water, 34 g of triethanolamine was added thereto, and the mixture was heated to 80 ° C. and deflocculated for 3 hours. Peptization rate is 62%
A large amount of unpeptized matter remained. Also, the deflocculated product had a remarkably distorted particle shape and had a very large particle size distribution. Comparative Example 2 The antimony pentoxide gel chiller obtained by the same method as in Comparative Example 1 was suction filtered, and then 3.5% hydrochloric acid aqueous solution. 3500 g was poured, the sodium ion in antimony pentoxide was removed, and then water washing was performed with 6000 g of water. It was possible to inject water up to about 4000 g, but if more water was injected, the partially decomposed glue of the antimony pentoxide gel proceeded and filtration became impossible.

Claims (1)

[Claims] 1. A method of reacting sodium antimonate with an inorganic acid to produce an antimony pentoxide gel, and then separating, washing and peptizing the gel to obtain an antimony pentoxide sol, comprising the steps of: a) chemically synthesizing sodium antimonate An antimony pentoxide gel is formed by reacting with a stoichiometric ratio of 0.5 to 5 times the amount of a monovalent or divalent inorganic acid, and b) separating the gel and washing with an aqueous solution of a monovalent or divalent inorganic acid. And further washed with an aqueous solution of a hydrophilic organic solvent and dispersed in water. C) An organic base is added to the dispersed aqueous solution in a stoichiometric ratio of 0.01 to 1 with respect to Sb ₂ O ₅ , or Phosphoric acid P ₂ O ₅ /
Sb ₂ O ₅ is added so that the weight% of Sb ₂ O ₅ is 0.2 to 5%, and peptized.
A method for producing an antimony pentoxide sol having a Na ₂ O / Sb ₂ O ₅ molar ratio of 0.001 to 0.2.