JPH0617233B2 - 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, in a method of obtaining an antimony pentoxide gel from an alkali antimonate and an inorganic acid and peptizing the gel, by adding phosphoric acid at the time of reaction and / or peptization, a pH of 1 to 4 can be obtained. It relates to a method for producing an antimony pentoxide sol for obtaining an antimony oxide sol.

(Prior Art) Antimony pentoxide sol is used as a flame retardant aid for plastics and fibers, plastics, microfillers for surface treatment of glass, inorganic ion exchangers, etc.
Generally, a high-concentration sol (Sb ₂ O ₅ 3
0-50%, pH 4-8) is used.

As a method for producing the antimony pentoxide sol, a method of deionizing an alkali salt of antimonic acid with an ion exchange resin (Japanese Patent Publication No. 57-11848, U.S. Pat. No. 41102).
47), a method of oxidizing antimony trioxide with hydrogen peroxide at high temperature (Japanese Patent Publication No. 53-20479, Japanese Patent Laid-Open No. 5-20479).
No. 2,212,98, JP-A No. 52-123997) and the like, the antimony pentoxide sol having a pH of 1 to 4 is stabilized with an organic base. Alternatively, a method of reacting an alkali antimonate with an inorganic acid and then deflocculating it (JP-A-60-4)
No. 1536) is known.

(Problems to be Solved by the Invention) The above-mentioned organic bases often reduce the strength of plastics and fibers, or deteriorate the thermal stability. Therefore,
There is a need for an antimony pentoxide sol containing no organic base and having a pH of 1 to 4, or an antimony pentoxide powder prepared from the sol. The antimony pentoxide sol having a pH of 1 to 4 is expected as a raw material for an organoantimony pentoxide sol using ethanol, isopropanol, butanol, ethyl cellosolve, DMF, toluene, xylene, solvent naphtha, etc. as a dispersion medium. .

As a conventional method for producing an antimony pentoxide sol having a pH of 1 to 4, there is the method described above. However, these methods have the following drawbacks.

The antimony pentoxide sol having a pH of 1 to 4 by the ion exchange method has colloidal particles having a shape close to a sphere, and has good dispersibility and stability, but in this method, antimony pentoxide (Sb ₂ It is difficult to manufacture with an O ₅ ) concentration of 10% by weight or more, and the process is complicated due to the separation and regeneration operations of the ion exchange resin, and a large amount of water is required for washing. have.

On the other hand, the hydrogen peroxide method directly uses antimony pentoxide (Sb
_Although a high concentration antimony pentoxide sol having a concentration of ₂ O ₅ ) of about 30% by weight and having a pH of 1 to 4 can be obtained, this sol has poor colloidal particle shape and thus has poor dispersibility and easily aggregates and precipitates upon storage. Since it has a large surface activity, it has a drawback of poor compatibility with acids, alkalis, inorganic salts, resin emulsions and the like. As a method for improving the stability of the antimony pentoxide sol obtained by the hydrogen peroxide method, 0.01 mol or more of an acid containing pentavalent phosphorus or arsenic is added to 1 mol of Sb at the time of producing the antimony pentoxide sol. A method has been proposed (West German Published Patent No. 2931523). In this reaction, the polymerization of antimonic acid is significantly suppressed by phosphoric acid, and polyantimonic acid ions or minute antimony pentoxide colloids of 5 mμ or less are generated, so the viscosity of the obtained sol is very high, and the viscosity increases remarkably upon storage. have.

The inventors of the present invention reacted an alkali antimonate with an inorganic acid, separated the obtained antimony pentoxide gel, washed it with water, and then peptized it with an organic base to obtain an antimony pentoxide sol (pH 4 to 4).
10.5) is passed through a column packed with a cation exchange resin to obtain a sol having a pH of 1.5 to 4 (JP-A-60-41536). The sol produced by this method has excellent stability, and the concentration of antimony pentoxide (Sb ₂ O ₅ ) at the time of ion exchange is limited to 15% by weight, and it is necessary to regenerate, wash and treat the waste liquid of the ion exchange resin. Therefore, there is a drawback that the manufacturing cost becomes high.

The object of the present invention is an industrial process for producing an antimony pentoxide sol, excluding the drawbacks of the conventional process for producing an antimony pentoxide sol having a pH of 1 to 4 described above.

(Means for Solving the Problems) The inventors of the present invention have conducted extensive studies as to a method for producing an antimony pentoxide sol which meets the above-mentioned object, and as a result, antimony pentoxide obtained by acid treatment of alkali antimonate was treated with phosphoric acid. It was found that by deflocculating, a target antimony pentoxide sol having a pH of 1 to 4 can be obtained.

That is, the present invention is a method of reacting an alkali antimonate with an inorganic acid to produce an antimony pentoxide gel, and then separating the gel, washing with water, and then peptizing to obtain an antimony pentoxide sol. The reaction is performed with a stoichiometric ratio of 0.5 to 5 times the amount of a monovalent or divalent inorganic acid, the temperature during peptization is set to 50 to 150 ° C., and phosphoric acid is added to P ₂ O ₅ during reaction and / or peptization. / Sb ₂ O ₅ wt% is 0.2 to 5.0
% So that the pH of the antimony pentoxide sol is adjusted to 1 to 4 with respect to the antimony pentoxide sol.

Antimonate alkali as a starting material of the present invention is illustrated as those in the general formula _{M 2 O · Sb 2 O 5} · xH 2 O (x = 0~6), M represents Na, an alkali metal K. Sodium is preferred as the alkali metal, and especially sodium antimonate hydrate Na ₂ O.Sb ₂ O ₅ .6H ₂ O (Sb ₂ O ₅ 6
4-65 wt%, Na ₂ O12~13 wt%, H ₂ O23
˜24% by weight) is preferred.

The acid that can be used in the process for producing the antimony pentoxide gel in which the alkali antimonate is reacted with the acid of the present invention is a monovalent or divalent inorganic acid such as hydrochloric acid, nitric acid, sulfuric acid, or sulfamic acid. Since phosphoric acid is a pentavalent acid like antimonic acid, antimony pentoxide gel cannot be obtained,
It becomes an aqueous solution of alkali antimonate phosphate. If the acid strength is weak, for example, the target antimony pentoxide gel cannot be formed with formic acid, oxalic acid, or the like.

In the reaction of the alkali antimonate of the present invention with the above acid, the concentration of the alkali antimonate can be 2 to 40% by weight as anhydrous antimony pentoxide (Sb ₂ O ₅ ) in the reaction solution. If it is less than 2% by weight, the production amount of antimony pentoxide gel is small, which is not economical. When it is 40% by weight or more, the solid content in the reaction solution becomes 60% or more, and the reaction becomes nonuniform, which is not preferable. It is preferably 6 to 25% by weight as anhydrous antimony pentoxide (Sb ₂ O ₅ ).

In the reaction between the alkali antimonate of the present invention and the above acid, the acid concentration is in the stoichiometric ratio of acid / alkali antimonate in the range of 0.5 to 5, preferably 1 to 3. Here, when the stoichiometric ratio is monovalent, [HX] / 2 [M ₂ O
・ Sb ₂ O ₅ · xH ₂ O] ratio ([] is the number of moles) [H ₂ X] / [M ₂ O · Sb ₂ O ₅ · xH ₂ O] in the case of divalent acid
Is a ratio. If the stoichiometric ratio is 0.5 or less, the desired antimony pentoxide gel cannot be obtained even if the reaction temperature and the alkali antimonate concentration are increased. Also, the stoichiometric ratio is 5
In the above case, the produced antimony pentoxide gel partially decomposes during washing and the sol is easily washed away in the filtrate, resulting in poor productivity.

In the reaction of the alkali antimonate of the present invention with the above acid, the reaction temperature is from room temperature to 100 ° C., and the reaction time is 0.5.
The reaction temperature is preferably 50 ° C. or less and the reaction time is preferably 10 hours or less in order to obtain an antimony pentoxide sol having a good particle shape, which can be longer than or equal to a time.

In the antimony pentoxide sol of the present invention, the antimony pentoxide colloid having a particle size of about 5 mμ to 20 mμ generated by the reaction is remarkably aggregated due to the acid and alkali metal salt in the system,
It is aggregated particles of about 3 μm or more and settled in the reaction solution. Therefore, this gel slurry can be separated very easily by a method such as pressure filtration, suction filtration, centrifugal filtration and the like. After filtration, washing is necessary to remove coexisting acid and alkali metal salt. In washing, the antimony pentoxide gel is partially deflocculated by contact with a large amount of water. Therefore, in any case of pressure filtration, suction filtration or centrifugal filtration, 0.5 to 4 times the reaction liquid volume is used. Immersion cleaning with pure water or distilled water must be done promptly.
The antimony pentoxide which is washed away by the method of the present invention by filtration and washing is 3% by weight or less.

The antimony pentoxide gel wet cake obtained by the above filtration and washing has a water content of 30 to 40%, and about half thereof is water of crystallization. The X-ray diffraction pattern of this antimony pentoxide gel is antimony pentoxide hydrate (Sb ₂ O ₅ · 4H ₂ O).
As with the above, the X-ray diffraction pattern of the raw material alkali antimonate is not recognized. In this antimony pentoxide gel, residual alkali metal was observed, and the M ₂ O / Sb ₂ O ₅ molar ratio was 0.1 to 0.6.

The antimony pentoxide sol having a pH of 1 to 4 can be obtained by dispersing the wet cake of antimony pentoxide gel in water, adding phosphoric acid, heating at 50 ° C. or higher and peptizing.

It is surprising that the antimony pentoxide gel hardly peptizes without the addition of phosphoric acid, and the addition of a small amount of phosphoric acid almost completely peptizes the gel.

The phosphoric acid of the present invention is orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, triphosphoric acid, tetraphosphoric acid and the like, which are easily available as commercial industrial products. Among phosphoric acids, orthophosphoric acid is most preferable.

Phosphate ion is strongly adsorbed on the surface of antimony pentoxide colloid (5mμ to 20mμ) of antimony pentoxide gel when phosphoric acid is added to antimony pentoxide gel containing alkali ion to bind with alkali metal ion. . If phosphoric acid is not added, the antimony pentoxide colloids will strongly bind to each other due to dehydration condensation due to heating, and will not be deflocculated, whereas antimony pentoxide colloids adsorbing phosphate ions will significantly suppress dehydration condensation even with heating. The alkali antimonate phosphate formed on the surface layer of the colloid upon heating is soluble in water, and therefore is peptized by heating.

In the present invention, phosphoric acid is strongly adsorbed to the antimony pentoxide gel and is not removed even by washing. Therefore, even if a small amount of phosphoric acid is added during the reaction between alkali antimonate and another inorganic acid, it is exactly the same as when added during peptization. Show the effect.
Similarly, phosphoric acid can be added both at the time of reaction and at the time of peptization.

By adding phosphoric acid during the reaction between alkali antimonate and an inorganic acid, the amount of alkali remaining in the produced antimony pentoxide gel is reduced as compared with the case where phosphoric acid is not added (M ₂
Reduce the O / Sb ₂ O ₅ molar ratio. ). This is because the adsorption of phosphoric acid on the surface of the gel prevents the ion exchanger antimony pentoxide from incorporating alkali ions in the solution into the structure.

In the present invention, phosphoric acid may be added alone or in a total amount of P ₂ O ₅ / Sb in any of the cases of adding during peptization, during reaction, and both of them.
₅ % by weight of ₂ O is 0.2 to 5.0%, preferably 0.
5 to 2.0%. When the amount added is 0.2% by weight or less, the peptization rate is remarkably reduced and the aggregated sediment is increased. Again 5
When the content is more than 10% by weight, deflocculation occurs, but the particle size of the antimony pentoxide colloid is small and the phosphoric acid in the liquid increases, so the viscosity of the sol increases and the resin emulsion, water-soluble polymer,
It is not preferable because the compatibility with acid, alkali, etc. deteriorates.

In the present invention, the peptization temperature is 50 ° C to 150 ° C,
Although peptization by an autoclave is possible, it is not economical and 60 to 100 ° C is preferable. The time for peptization depends on the peptization temperature and the peptization concentration, but is 0.5 to 10 hours.

The peptizing concentration in the present invention is anhydrous antimony pentoxide (Sb
₂ O ₅ ) can be from 2 to 30% by weight. When the deflocculating concentration is low, the deflocculating sol can be concentrated by a method such as an evaporation method, an ultrafiltration method or a reverse osmosis method. If the concentration is 2% or less, the concentration cost is high, which is not economical, and if it is 30% or more, the deflocculated antimony pentoxide colloid tends to reaggregate and settle, which is not preferable.

The antimony pentoxide sol obtained in the present invention has a pH of 1 to 4, and this sol contains lithium hydroxide, sodium hydroxide,
Potassium hydroxide, ammonia, triethanolamine,
The pH can be adjusted to 4 to 10.5 by adding a base such as monoethanolamine, quaternary ammonium hydroxide, guanidine hydroxide, and the like, which is concentrated to give antimony pentoxide (Sb ₂ O ₅ ). As a result, a sol of 30 to 50% by weight can be obtained.

The particle size of the antimony pentoxide colloid obtained in the present invention is 5 to 40 mμ as observed by an electron microscope, the particle shape is almost spherical, and the particle size distribution is also very small.

The antimony pentoxide sol obtained in the present invention can be made into a powder by being dried as it is with a spray drier, and is effective as a flame retardant aid such as vinyl chloride and polyester resin. The antimony pentoxide sol of the present invention has good compatibility with alcohols and the like, and when added to an alkoxysilicone surface treatment agent or the like, the transparency of the film is improved.

Next, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to these examples. In the examples,% is% by weight, and sodium antimonate used was Sb ₂ O ₅ 64% and Na ₂ O.
It has a composition of 12.5% and H ₂ O 23.5%.

Example 1 800 g of sodium antimonate was dispersed in 830 g of pure water, 420 g of 35% hydrochloric acid was added with stirring, and the mixture was heated to 30 ° C. and reacted for 4 hours. The concentration of antimony pentoxide in the reaction solution was 25.0% as Sb ₂ O ₅ , and the stoichiometric ratio of hydrochloric acid / sodium antimonate was 1.27.
Next, the antimony pentoxide gel slurry produced by the reaction was suction-filtered, 1800 g of pure water was poured, and washing was performed. The obtained antimony pentoxide gel wet cake 83
_{0g (Sb 2 O 5 61.7%} , Na 2 O3.7%, H 2 O3
4.8%, Na ₂ O / Sb ₂ O ₅ molar ratio of 0.313) was dispersed in 2490 g of pure water, 8.5 g of 85% orthophosphoric acid was added to this with stirring, and the mixture was heated to 80 ° C. and Time deflated. The amount of phosphoric acid added was 1.02% by weight of P ₂ O ₅ / Sb ₂ O ₅ and the peptization rate was 98.5%.

The obtained sol had a specific gravity of 1.162, pH of 2.20, viscosity of 1.8 cp, Sb ₂ O _{5 of} 15.4%, and Na ₂ O of 0.92.
%, P ₂ O ₅ 0.16%, Cl 200 ppm, particle size 20
.About.25 mμ, the particles were almost spherical. Further, this sol was stable even after being stored at 50 ° C. for 1 month, with no increase in viscosity and no formation of sediment.

Example 2 415 g of antimony pentoxide gel wet cake (Sb ₂ O ₅ 61.0%) obtained under the same reaction conditions as in Example 1 was added to water 61
Dispersed in 5 g and stirred with 85% orthophosphoric acid 9.0
g was added, and the mixture was heated to 75 ° C. and deflocculated for 3 hours. P ₂
The O ₅ / Sb ₂ O ₅ weight% was 2.19% and the peptization rate was 99%.

The obtained sol has a specific gravity of 1.242, a pH of 2.10 and a viscosity of 3.
_{0cp, Sb 2 O 5 24.4%} , Na 2 O1.51%, P 2
O ₅ 0.53%, Cl325ppm, particle size 10 to 20
It was mμ. This sol was stable even after storage at 50 ° C. for 1 month (no increase in viscosity, no precipitate formation was observed).

Example 3 1000 g of sodium antimonate was dispersed in 870 g of pure water, 270 g of 35% hydrochloric acid and 5.4 g of 85% orthophosphoric acid were added with stirring, and the mixture was heated to 40 ° C. and reacted for 6 hours. The concentration of antimony pentoxide in the reaction solution was 29.8% as Sb ₂ O ₅ , the stoichiometric ratio of hydrochloric acid / sodium antimonate was 0.65, and the weight ratio of P ₂ O ₅ / Sb ₂ O ₅ was 0.52%. Is.

Then, the antimony pentoxide gel slurry produced by the reaction was suction-filtered, and 3200 g of pure water was poured to wash. The obtained antimony pentoxide gel wet cake 10
_{50g (Sb 2 O 5 61.0%} , Na 2 O5.6%, H 2 O
33.4%, Na ₂ O / Sb ₂ O ₅ molar ratio 0.48) was dispersed in 4250 g of pure water, heated to 90 ° C., and peptized for 5 hours. The peptization rate was 97%.

The obtained sol has a specific gravity of 1.125, a pH of 3.15, a viscosity of 1.5 cp, Sb ₂ O ₅ 12.1% and Na ₂ O 1.11.
%, P ₂ O ₅ 0.063%, Cl ₃ 180 ppm, and a particle size of 25 to 30 mμ. This sol was stable even after being stored at 50 ° C. for 1 month without any increase in viscosity or formation of precipitate.

To 300 g of this sol, 60 g of triethanolamine was added to adjust the pH to 6.5, and then anhydrous antimony pentoxide (Sb ₂ O ₅ ) was added at a liquid temperature of 70 ° C. with a rotary evaporator.
It was concentrated to a concentration of 50%.

The obtained sol had a specific gravity of 1.910, a pH of 6.5 and a viscosity of 9.
It was ₅ cp and Sb ₂ O _{5 was} 49.5%.

Example 4 600 g of sodium antimonate was dispersed in 1790 g of pure water, 350 g of 35% hydrochloric acid and 3.0 g of 85% orthophosphoric acid were added with stirring, and the mixture was heated to 25 ° C. and reacted for 4 hours. Sb ₂ O ₅ concentration in the reaction solution was 14.0%, hydrochloric acid /
The stoichiometric ratio of sodium antimonate is 1.41, P ₂ O ₅ /
The Sb ₂ O ₅ weight% is 0.48%. Then, the antimony pentoxide gel slurry produced by the reaction is suction-filtered,
Purified water (4200 g) was poured and washed. 650 g of the obtained antimony pentoxide gel wet cake (Sb ₂ O ₅ 5
9.1%, Na ₂ O 2.8%, Na ₂ O / Sb ₂ O ₅ molar ratio 0.247) were dispersed in 3300 g of pure water, and while stirring, 3.5 g of 85% orthophosphoric acid was added, and the mixture was heated to 80 ° C. Peptization was performed for 2 hours. The peptization rate was 98%.

The obtained sol had a specific gravity of 1.105, pH of 1.98, viscosity of 1.4 cp, Sb ₂ O _{5 of} 9.71%, P ₂ O ₅ / Sb ₂ O ₅ weight% of 1.04%, and a particle diameter of 25 to 35 mμ. there were. The particle shape was almost spherical. This sol was concentrated by an evaporator at 90 ° C. to an antimony pentoxide (Sb ₂ O ₅ ) concentration of 20%. The obtained sol has a specific gravity of 1.222 and a pH of 1.
The viscosity was 95 and the viscosity was 25 cp. This sol was stable although it exhibited thixotropy upon storage.

Example 5 480 g of sodium antimonate was dispersed in 2420 g of pure water, 380 g of 40% sulfuric acid was added with stirring, and the mixture was heated to 45 ° C. and reacted for 5 hours. S in the reaction solution
The b ₂ O ₅ concentration is 9.36%, and the sulfuric acid / sodium antimonate stoichiometry is 1.63. Then, the antimony pentoxide gel slurry produced by the reaction is suction-filtered to obtain pure water 3
It was washed by pouring 500 g of water. 510 g of the obtained antimony pentoxide gel wet cake (Sb ₂ O ₅ 60.2
%) Is dispersed in 1970 g of pure water and 10% while stirring
50 g of a pyrophosphoric acid aqueous solution was added, and peptization was performed at 100 ° C. for 1 hour. Kainikawaritsu was 99% with _{P 2 O 5 / Sb 2 O} 5 weight percent 1.30%.

The obtained sol has a specific gravity of 1. 128, pH 2.50, viscosity 1.6 cp, Sb ₂ O ₅ 12.1%, Na ₂ O 0.81
%, Na ₂ O / Sb ₂ O ₅ molar ratio 0.349, particle size 20
.About.25 mμ, and the particle size was almost spherical. This sol was stable without storage for 1 month at 50 ° C. and no thickening or precipitation was observed.

Comparative Example 1 800 g of sodium antimonate was dispersed in 1680 g of pure water, 510 g of 35% hydrochloric acid was added with stirring, and the mixture was heated to 30 ° C. and reacted for 4 hours. The concentration of antimony pentoxide in the reaction solution was 17.1% as Sb ₂ O ₅ , and the stoichiometric ratio of hydrochloric acid / sodium antimonate was 1.54.
Then, the antimony pentoxide gel slurry produced by the reaction was suction-filtered, and 2500 g of pure water was poured to wash. The obtained antimony pentoxide gel wet cake 84
_{0g (Sb 2 O 5 61.0%} , Na 2 O3.4%, Na 2 O
/ Sb ₂ O ₅ molar ratio 0.291) was dispersed in 4100 g of pure water, 4.0 g of 10% orthophosphoric acid was added thereto with stirring, and the mixture was heated to 80 ° C. and deflocculated for 5 hours. At the time of peptization, the concentration of antimony pentoxide was 10.4% of Sb ₂ O ₅ , the addition amount of phosphoric acid was P ₂ O ₅ / Sb ₂ O ₅ % by weight of 0.057%, and the peptization rate was 10%.

Comparative Example 2 840 g of an antimony pentoxide gel wet cake obtained under the same reaction conditions as in Comparative Example 1 was dispersed in 3350 g of pure water, then 45 g of 85% orthophosphoric acid was added, and peptization was carried out at 85 ° C. for 3 hours. At the time of deflocculation, the Sb ₂ O ₅ concentration was 12.1%, the addition amount of phosphoric acid was 5.41% at P ₂ O ₅ / Sb ₂ O ₅ % by weight, and the deflocculation rate was 99%. However, the viscosity of the obtained antimony pentoxide sol was 110 cp, and showed a remarkable tendency of thickening upon storage at 50 ° C.

Comparative Example 3 420 g of antimony pentoxide gel wet cake (Sb ₂ O ₅ 61.0%) obtained under the same reaction conditions as in Comparative Example 1 was added to pure water 1
Dispersed in 460 g, then 85% orthophosphoric acid 4.0 g
Was added and deflocculation was performed at 40 ° C. for 10 hours. However, no peptization was observed. Sb ₂ O ₅ concentration at peptization 13.6
%, The addition amount of phosphoric acid is 0.96 in P ₂ O ₅ / Sb ₂ O ₅ weight%.
%.

Claims (1)

[Claims] 1. A method of reacting an alkali antimonate with an inorganic acid to produce an antimony pentoxide gel, separating the gel, washing with water, and then peptizing to obtain an antimony pentoxide sol. The stoichiometric ratio is 0.
5-5 is reacted with volumes of monovalent or divalent inorganic acid, a temperature of 50 to 150 ° C. during _{peptization, P 2 O 5 / Sb 2} O 5 weight phosphoric acid on reaction time and / or peptization % So that the pH of the antimony pentoxide sol is 1 to 0.2% to 5.0%.
4. A method for producing an antimony pentoxide sol, characterized in that