SU1664745A1 - Method of producing stable alkaline reversible silica sols - Google Patents

Abstract

The invention relates to methods for producing stable, alkaline, reversible silica salts used in the manufacture of polishing compositions for the precision polishing of various electronic materials in the production of catalysts, inorganic fibers and produces a product with a diameter of 7-20 nm. The deionized silica sol is treated first with an alkali metal aluminate solution, taken in an amount in terms of AL ₂ O ₃ / 5-7 ^. 10 ^-7 mol per 1 m ² surface of silicazole, and then with a solution of the modifier — triethanolamine or a low molecular weight quaternary ammonium base in an amount that provides (6 - 10) ^. 10 ^-4 g of modifier per 1 m ² surface silica sol.

Description

The invention relates to methods for producing stable, alkaline, reversible silica salts used in the manufacture of polishing compositions for precision polishing of various materials of electronic engineering, in the production of catalysts, inorganic fibers.

The purpose of the invention is to provide the possibility of obtaining a product with particles with a diameter of 7-20 nm.

Example 1. Silica sol with a SIO2 concentration of 250 g / l, oH 9.3, particle diameter 7 nm, 5UD 390 tr / rt, stabilized with caustic soda, an aqueous solution of sodium aluminate with a concentration of ADOz - 100 g / l 30% solution of tetramethylammonium hydroxide (TMA).

Aluminization of silica sil is carried out as follows.

With vigorous stirring at a rate of 100 ml / h, 500 ml of sodium alumina solution (in terms of AlaOa 7 mol / m SiOa) is added to 500 ml of silicazol with vigorous stirring at the blade of the m stir bar.

Next, the resulting solution is passed through cation and anion exchange resins to remove excess electrolytes. The silica sol obtained in this way has a pH value of 3.3.

Then, 97 ml of TMA solution, which is 6-10 g / m SI02, are added to the purified silica sol with vigorous stirring. The silica sol obtained has a pH value of 11.9 and is distinguished by a rather high stability — resistance to changes.

ABOUT

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its main parameters of dispersed composition and pH in time (at least for 3 months).

The product has a 100% reversibility: after drying to a powder and re-dispersing in water, it forms a colloidal solution with the original parameters,

Example 2. Silicon dioxide hydrosol with a S102 concentration of 360 g / l, a pH of 9.1, a particle diameter of 12 nm, 5 yd 13.6 m2 / g, stabilized with caustic soda, an aqueous solution of sodium aluminate with a concentration of - 100 g / l, 30% solution of TMA.

The surface alumina of silica-silica particles is carried out as in Example 1, however, 24.8 ml of sodium aluminate solution (based on AlaOa 6 mol / m2 SiCte) are added to 500 ml of silica-gel.

After treatment with ion exchange resins, 98 ml of TMA solution is added to the resulting solution with stirring, which amounts to 7,104 g / m2 SI02.

The resulting product has a pH of 11.8 and is resistant to changes in the basic parameters for at least 3 months. The degree of reversibility is 100%.

Example 3. Silicon dioxide hydrosol with a concentration of SiO2 of 350 g / l, pH 9.1, particle diameter of 20 nm, 5 yd 136 m2 / g, stabilized with caustic soda, an aqueous solution of sodium aluminate with a concentration of A1203 is used as initial solutions. g / l, 30% solution of TMA,

The silica surface of the silica-alumina surface is carried out as in Example 1, however, in this case, to 500 ml of silica-salt is added

12.6 ml of sodium aluminate solution (in terms of 5 mol / m2 Si02).

After treatment with ion exchange resins, 67 ml of TMA solution is added to the resulting solution with stirring, which amounts to 8 g / m2 SI02.

The resulting product has a pH value

11.7 and resistant to changes in the basic parameters, at least for 3 months. The degree of reversibility is 100%.

Example 4. Silicon dioxide hydrosol with a concentration of 400 g / l SI02, pH 9.0, particle diameter 15 nm, stabilized with a solution of sodium hydroxide, an aqueous solution of sodium aluminate with

concentration of ABOZ 100 g / l, a solution of triethanolamine,

Silica-silica particle surface alumina. The procedure was carried out as in Example 1, however

in so doing, 21.6 ml of sodium aluminate solution (in terms of 6 mol / m2 Sfcte) are added to 500 ml of silica sols.

After treatment with ion exchange resins, 40 ml of a solution of triethanolamine, which is 10 g / m <25> <2>, are added with stirring to the resulting solution.

The resulting product has a pH of 11.1 and is resistant to changes in basic

parameters for at least 3 months. The degree of reversibility is 100%.

The prototype receive a stable reversible product with a particle size of at least 15 nm.

Thus, the use of the invention makes it possible to obtain stable in / time with respect to the main parameters (pH, dispersed composition, average particle diameter) alkaline reversible

silica sols with a small diameter of particles that can be used, first of all, as effective agents for precision polishing of various materials of electronics materials. Product can

also be used as a binder, filler in the manufacture of sorbents, catalysts, etc.

Claims (1)

Invention Formula A process for the preparation of stable alkaline reversible silicosols, comprising mixing deionized silica sol with a solution of triethanolamine or a low molecular weight quaternary ammonium base, characterized in that, in order to ensure the possibility of using the product in precision polishing by obtaining it with particles with a diameter of 7-20 nm, before the mixing step preliminarily treating the silica sol with an alkali metal aluminta solution, taken in an amount in terms of alumina (5-7) mol per 1 m of the surface; the silica sil is mixed in amounts that provide (6-10) g of nitrogen-containing organic matter per 1 m surface silica sol.