CS239831B1 - A method for preparing a silica-based dispersion material - Google Patents

Abstract

The invention relates to a method of preparing material based on silicon hydroxide. The essence of the preparation is that, in the first stage, a solution of the acid salt of silicic acid is prepared by mixing a solution of sodium or potassium silicate with a solution of an inorganic) or organic acid. In the second stage, this acid salt is mixed with a solution of sodium or potassium silicate, heated to a temperature of 50 to 99 °C, so that 30 to 50% of the volume of the acid salt is added during the first 10 to 20% of the total reaction time, then the mixture is allowed to ripen for 30 to 60% of the total reaction time, the rest of the acid salt is added and allowed to ripen for up to 90% of the total reaction time, after which the mixture is neutralized with acid to pH 5 to 4. The total reaction time is 60 to 120 min. The resulting suspension is separated from the mother solution, the filter cake is washed, dried, crushed and sorted by size. The invention is used as an active thickener in the rubber industry, the plastics industry, the pharmaceutical industry, and the paper industry.

Description

(54) A method of preparing a dispersion or silica hydrooxide-based material

The present invention relates to a process for the preparation of a silica hydrooxide material. The essence of the preparation consists in that in the first step a solution of an acidic silica sol is prepared by mixing a solution of sodium or potassium silicate with a solution of inorganic) or an organic acid. This acid sol is mixed in a second step to a solution of sodium or potassium silicate heated to 50 to 99 ° C by adding 30 to 50% of the volume of the acid sol during the first 10 to 20% of the total reaction time, then leaving the mixture maturate to 30-60% of the total reaction time, add the remaining acid sol and allow to mature to 90% of the total reaction time, then neutralize the mixture to pH 5 to 4. The total reaction time is 60 to 120 min. The resulting suspension is separated from the mother liquor, the filter cake is washed, dried, crushed and sized vigorously.

The invention has use as an actively thickening agent in the rubber, plastics, pharmaceutical, paper and paper industries.

2398 31

The invention relates to a process for the preparation of a silica hydrooxide dispersion material.

Most of the known processes for the preparation of precipitated hydrated silica are based on aqueous solutions of alkali silicates, e.g. j. water glass, from which silica hydrooxide is precipitated by inorganic acids (British Patent No. 1 1312 831; British Patent No. 1105 658). According to British patent no. 710 015, the silicate solution is precipitated by acids in the presence of sodium chloride. In another method, dilute silicate and acid solutions are introduced into the silicate solution, but separately, at the same time (British Patent No. 1,043,282).

U.S. Pat. No. 2,601,235, silica hydride is prepared by simultaneously adding dilute waterglass and sulfuric acid to an alkali silica sol) under defined concentration, time and temperature conditions.

Other approaches use acid-reacting gases, such as sulfur dioxide or carbon dioxide, to precipitate silica hydrooxide from silicate solutions (British Patent No. 945,123; British Patent No. 1,122,588; British Patent No. 1122,589).

A more advantageous method has now been found, the essence of the present invention being the preparation of silica hydrooxide carried out in two stages:

In the first step, an acidic silica sol is prepared by mixing an acid selected from the group of inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, or organic acids such as e.g. formic acid or acetic acid, with a corresponding acid concentration between 5 to 35%, preferably 10 to 30%, with an alkali metal silicate solution, preferably sodium or potassium silicate, with a concentration of 30 to 300 g of silica in 1 liter of silicate solution.

The acid sol thus prepared is admixed in a second step to a solution of sodium or potassium silicate heated to 50 to 99 ° C, preferably above 90 ° C, having an initial concentration of 30 to 250 g of silica in 1 liter of the silicate solution, preferably 40 to 120 g of silica in 1 liter of silicate solution.

The mixing of the acid sol solution is done with stirring by adding 30 to 50% of the volume of the acid sol to the silicate solution during the first 10 to 20% of the total reaction time, then allowing the reaction mixture to mature to 30 to 60% of the total The reaction mixture is allowed to mature to 90% of the total reaction time, and the reaction mixture is neutralized and diluted to 5 to 20% of the total reaction time. 25% acid, preferably of the same kind as used in the preparation of the acid sol, so that at the end of the reaction the mixture has a pH equal to or lower than

5th

The amount of acid used to form the acid sol represents 50 to 80% of the total amount of acid required to completely react and neutralize the alkalinity of the entire silicate batch, i. j. the silicate used to prepare the acid sol in the first stage together with the silicate from the reaction batch in the second stage, to a pH equal to or less than 5.

The amount of silicate used to prepare the acid sol in the first step represents 30 to 50% of the total amount of silicate used in the reaction process in both steps. The total reaction time is understood to be the time from the start of the addition of the acid sol to the silicate feed in the second stage until the pH is reached = 5 at neutralization. Usually, this time is in the range of 60 to 120 minutes.

The suspension obtained is then separated from the mother liquor by filtration or centrifugation, the filter cake is washed with water to get rid of the mother liquor residue and dried. A drying temperature of 60 to 300 ° C is recommended. Desserts shall be ground or crushed and sized if necessary.

An advantage of the invention is to obtain a product with higher technical parameters.

Example ¹

120 l of water and 20 l of 65% by weight nitric acid are introduced into the enamelled boiler with stirrer. After 1 min at 5Ό ¹ is mixed 220 1 potassium silicate solution with a concentration of 48 g silica in 1 liter of a solution of silicate.

After all the silicate has been admixed, the acid sol is heated to 50 ° C and immediately added to the reactor equipped with a stirrer and a heating coil. 100 l of a potassium silicate solution having a concentration of 110 g of silica per liter of solution preheated to a temperature of 55 DEG C. is provided. The addition of the acid sol is carried out continuously and with stirring at a rate such that 160 l of the acid sol solution is admitted over 15 minutes. About 5 minutes from the start of the purging, turbidity begins to build up, the intensity gradually increasing while increasing the viscosity of the reaction mixture.

During the addition, the reaction mixture is heated vigorously in the reactor so that the temperature at the end of the addition after 15 min reaches at least 70 ° C. After adding the above 160 L acid sol solution, the mixture is only stirred for 20 minutes while maintaining the temperature above 70 degrees C. During this maturation period, the maximum viscosity increases and the viscosity gradually decreases. After this maturation period, the addition of the remaining (200 L) of the acid sol, which is continuously and continuously continued, is again added while stirring and maintaining the temperature above 70 ° C to allow the reaction mixture to be introduced for 20-25 minutes.

The reaction mixture is aged for 20 min. Dilute 10% by weight nitric acid is then added thereto to neutralize the remaining alkalinity for 10 min and the suspension reaches pH '= 5. The suspension is discharged from the reactor through a filter device, where the mother liquor is removed, after which the filter the cake is dried at 150 ^° C.

More than 23 kg of silica hydrooxide material is obtained in the form of lumps which, after grinding to a grain size below 50 µm, can be used as a filler. Potassium nitrate can be crystallized from the mother liquor after concentration.

Example 2

In a reaction vessel, a feed of 36 kg of 93 percent by weight of sulfuric acid in 200 L of water is charged with stirring with 200 L of sodium silicate solution, 175 g of silica in 1 L of silicate solution. The acid sol obtained is then heated to 90 DEG C. and immediately admitted to a reactor equipped with a stirrer and a heating system in which 1000 l of water are heated to 93 ^DEG C. together with 200 l of sodium silicate containing 305 g of silica. in 1 liter.

The acid sol is stirred pripúšfa rýchlosfou 15 1 min ^-1 for 12 min, then is quenched and the mating mixture in the reactor while maintaining the temperature 93 to 9® ° C for 40 minutes only stirred. After this time, the addition of the acidic sol is started again until all of the soles are admitted to the reactor (16 min) while maintaining the temperature at 95 + 2 ° C. Up to 90 min from the start of the reaction, i. from the start of adding the first portion of the acid sol to the reactor, the mixture is allowed to mature, and then the addition of diluted 15% by weight of sulfuric acid to the reactor is started to neutralize the reaction mixture for 10 min to reach pH 5 .

The reaction slurry was passed through filter presses, washed, and the filter cake was dried at temperatures of 120-150 ° C. The resulting pellets are ground. It gets around. 100 kg of finely powdered silica hydrooxide. Crystalline sodium sulfate can be obtained from the mother liquor after concentration.

Example> 1 and d 3

To 100 l of 37% by weight of hydrochloric acid diluted with 100 l of water, a total of 200 l of sodium silicate at a concentration of 136 g of silica in 1 liter of silica solution was slowly added with vigorous stirring.

sodium citrate. The resulting acid sol was added to a 450 L solution of 85 g of silicon dioxide sodium per liter of silicate solution present in the reactor and heated to 92 ° C by adding 180 L of acid sol during the first 15 min. the mixture is aged for 40 min with stirring, then the remaining 220 liters of the acid sol solution are added over a further 20 min. ^;

After addition of all the sol, the reaction mixture is allowed to mature with stirring, then a 5% by weight solution of hydrochloric acid is added over 10 minutes until the pH of the reaction mixture reaches 5 to 4. The suspension is transferred to a filter, washed from the mother liquor and dried. . The pellets are ground to a particle size below 40 μπι.

Example 4

The boilers were charged with 10 L of 99% formic acid together with 90 L of water. To this solution is added at a rate of 5-7 l min ¹ solution, prepared by mixing 50 l of sodium silicate at a concentration of 305 g silica in 1 liter of solution, with 20 l of water. The resulting acidic silica sol j is admixed to a batch formed by mixing 90 L of 1.37 g cm ^-3 sodium water glass and 800 L of water heated to 93 ° C such that 80 L of water is allowed in the first 10 min. the acid sol, whereby the reaction mixture is aged for 30 minutes while maintaining the temperature at 95 ° C and stirring.

After this time, oipaf will begin to add the acid sol at a rate of 5 to 6 1 min ¹ . After all the sol was added, the reaction mixture was aged again for 30 minutes, after which the whole mixture was neutralized and adjusted to pH 5 by the addition of dilute 10-15% by weight of formic acid.

The suspension is freed from the mother liquor, washed and dried at 120 to 200 ° C. The pellets are comminuted to a size below 50 μΐη.

Example 1 and d 5

The boilers are charged with 120 L of 95% acetic acid and 1000 L of water and 1000 L of sodium silicate solution containing 105 g of silica in 1 L of solution is added with stirring. The acid sol thus prepared is after being heated to 80 degrees G and is vigorously stirred for 5 minutes at a rate of 1.8 to 2 liters with ¹ to 3,000 liters at 95 DEG C. of 2 DEG C. of a preheated 31 g silica solution of sodium silicate. per 1 liter of solution, maintaining the temperature at 92 + 2 ° C.

After this time, the solubilization is stopped and the heated solution of sodium silicate at a concentration of 38 g of silicon dioxide in 1 liter of solution, at a rate of 10-12 ls ^-1 , a total of 2,800 l, is immediately started.

After the addition of the silicate solution, it is mixed for 10 minutes and then the addition of the acid sol residue is started at a rate of 1 to 2 l s ^-1 .

After all the sol has been admixed, 10 to 20% by weight of acetic acid is added to the slurry with stirring until the pH of the slurry is adjusted to 5.5 to 6. The slurry is freed from the mother liquor, washed, dried and ground to give a granular material. under 60 «m.

Example 6

In a stirred vessel, 30 L of 93% by weight sulfuric acid is mixed with 300 L of water, and a solution of 370 L of sodium silicate of 145 g silica in 1 L of silicate solution is allowed to stir. The resulting acid salt is heated to 90 DEG C. and at 35 to 37 1 ^min-1 was blended in batch, consisting of 300 1 of water glass solution with a density of 1.37 g cm ^3, and 1800 liters of water, heated to 95 ° C .

After 10 min, the addition of the acid sol is stopped, the reaction mixture is aged for 12 min before starting to add the acid sol at the same rate as before, stirring and maintaining the temperature between 90-95 ° C.

After all the acid sol has been introduced, the reaction mixture is aged for 30 min, after which 10% by weight of sulfuric acid is allowed to neutralize and adjust the pH of the suspension to 5 to 4. After filtering and washing, the filter cake is dried and crushed. that the grain size of the material is below 60 μία.

Example 7

A total of 250 liters of sodium silicate solution with a concentration of 143 g of silica in 1 liter of solution was added to the feed of 20 L of 93% sulfuric acid in 220 L of water at a rate of 25-30 L min ^-1 with vigorous stirring. This acid sol after heating at 90 DEG C. at 25 1 min ^"1 for 10 minutes blended in a reactor containing 1 400 1 sodium silicate solution at 43 g silica in 1 liter of solution, heating to 95 ± 3 ° C.

After the addition of 250 L of the acid sol solution, the reaction mixture is aged for 12 min while stirring and maintaining the temperature at 95 ° C, after which the remaining portion (250 L) of the acid sol is added over 12 min. The mixture is aged at 95 + 3 ° C for a further 60 min.

Finally, 10 percent by weight sulfuric acid is added to the reaction mixture so that the reaction mixture reaches a pH of 5 to 4 within 10 min. After separating the suspension from the mother liquor and washing, the filter ball is dried at 120-150 ° C, dried. grind or crush talk to max. the particle size was below 40 µm. Example 8

The first portion, 300 l hot, to 90 ° C of heated solution, is allowed to stir for 2 min into a 17Ό0 L batch containing a solution of sodium silicate of 35 g silica per liter of solution heated to 96 ° C over 2 min. an acid sol prepared by mixing a total of 400 L of a 153 g silica glass water solution per liter solution, with 45 kg of 93% sulfuric acid in 190 L water.

After stirring for 5 min, the addition of the second portion of the acid sol was started at a rate of 15 l min ^-1 while stirring and heating the reaction mixture to above 90 ° C. After all the acid sol was added, the mixture was aged with stirring for 50 min, after which 8% by weight sulfuric acid was added until the reaction mixture was adjusted to a pH of 4-5.

After filtering and washing with water, the filter cake is dried at 220 ° C and crushed to a particle size below 40 μΐη.

The invention can find widespread use as a filler in the rubber, pharmaceutical, paint and varnish industries and in the paper industry.

Claims (1)

After addition of the silicate solution, the mixture is still stirred for 10 minutes and then the residue of the acidic sol is started, at a rate of 1-2 liters. After all of the sol has been added, dilute 10-20% by weight of ootic acid is added to the suspension with stirring until the pH of the suspension is adjusted to 5.5 to 6. The suspension is freed from the mother liquor, washed, dried and ground to give. to have a particle size of less than 60 microns. EXAMPLE 6 30 l of 93% by weight sulfuric acid with 300 l of water are mixed in a stirrer with stirring, a solution of 370 l of sodium silicate at a concentration of 145 g of silica in 1 l of silicate solution is allowed to stir. . The resulting acid sol is heated to 90 ° C and stirred at 35-37 1 min-1 to a batch of 300 liters of 1.37 g cm -1 of water and 1000 liters of water heated to 95 ° C. C. After 10 min, the acid solute suspension is allowed to settle, the reaction mixture is aged for 12 min, and again the acid sol is allowed to adhere equally at a rate of 90 to 95 ° C with stirring. After all the acidic sol has been introduced, the reaction mixture is left to stir for 30 min, then 10% by weight of acidic acid is allowed to neutralize and the pH of the suspension is adjusted to 5 to 4. After filtration and washing, the filter cake is dried and dried in a drying tray. EXAMPLE 7 A total of 250 liters of sodium silicate solution with a concentration of 143 g of silicon dioxide is added to a 20 liters of 93% by weight of acidic acid in 220 liters of water. in a 1 liter solution at a rate of 25 to 30 1 min -1 with intensive stirring. This acidic sol is heated to 90 ° C at 25 1min -1 for 10 min and stirred into a reactor 8 which contains 1400 L of silicon dioxide solution at a concentration of 43 g of silica in a 1 liter solution heated to 95 ° C. + 3 ° C. After the addition of 250 L of the acidic sol solution, the reaction mixture is allowed to agitate for 12 min by stirring and maintaining the temperature at 95 ° C, allowing the other portion (250 L) of the acidic sol to adhere for 12 min. aging at 95 ± 3 ° C. 10% by weight sulfuric acid is added to the reaction mixture until the pH of the reaction mixture reaches pH 5 to 4 within 10 minutes. After separation of the solution solution suspension and washing, the filter cake is dried at 120 to 150 ° C C. Drying or drying to a maximum particle size below 40 .mu.m Example 8 To 1700 L of feed containing 35 g of sodium silicate solution. of silica per 1 liter of solution, heated to 96 ° C, is stirred for 2 minutes with vigorous stirring of the first portion, 300 L of hot, at 90 ° C of heated acid sol solution prepared by mixing a total of 400 L of solution. water glass by concentrating 153 g of silica per liter of solution, with 45 kg of 93% by weight sulfuric acid in 190 liters of water. After stirring for 5 min, the addition of a second portion of the acidic sol is initiated at a rate of 15 1 min -1 with stirring and heating of the reaction mixture to a temperature above 90 ° C. 50 min, then 8% by weight sulfuric acid is added until the reaction mixture is adjusted to pH 4 to 5. After filtering and washing with water, the filter cake is dried at 220 ° C and dried to a particle size below 40 µm. widespread use in rubber industry, pharmacy, paint and varnish industry and paper industry PRED Μ ET A method for the preparation of a dispersion material of silica base based on alkali metal silicate solutions and inorganic and organic acids, characterized in that an acid solution of silicic acid sol is prepared in the first stage mixing the acid selected from the group consisting of sulfuric acid , nitric, hydrochloric, acetic, formic, at a concentration of 5 to 35% by weight, preferably at a concentration of 10 to 30% by weight, with a solution of siliceous sodium or potassium at a concentration of 30 to 300 g of silica per liter of silicate solution, in the second step of the invention, this acidic sol is allowed to react by successively admixing it to a solution of silicate sodium or potassium at a temperature of 50 to 99 ° C, preferably above 90 ° C, wherein the concentration of the sodium or potassium silicate solution to which the acidic sol is stirred is 30 to 250 g of silicon dioxide per liter of solution, preferably having a concentration of between 40 and 120 g of silicon dioxide per liter of silicate, wherein the addition of the acidic sol is preferably carried out such that 30 to 50% The volume of the acid sol is added to the silicate solution after the time of the first 10 to 20% of the total time of re-action, then the reaction mixture is left to dry. The aging and maintaining temperature ranges from 30% to 60% of the total reaction time, and then, with agitation, during the period of 1% to 20% of the total reaction time, increases from 50% to 70% by volume of the acid sol solution, allowing up to 90% of the total reaction time to mature. during the remaining 10% of the total reaction time, the reaction mixture is neutralized and treated with a solution of the acid such that at the final reaction time the reaction mixture has a pH of from 5 to 4, with the same acid being advantageously used as the preparation for the acidic sol. wherein the amount of silicate used to prepare the acidic sol in the first stage is from 30 to 50% of the total amount of silicate used in the two steps, the amount of acid used to form the acidic sol in the first stage is from 50 to 80% of the total amount - the amount of acid needed to realize the total amount of silicates used in both stages h to react to 5 to 4, the cellular reaction time is in the range of 60 to 120 min, wherein the total time -reaction is understood to be the time from the addition of the acidic sol to the silicate solution to the second stage up to a pH of 5 to 4 for neutralization the suspension is separated from the parent solution, preferably by filtration or centrifugation, washed to remove residual mother liquor with water, the wet material is dried, the desserts are ground or crushed, optionally sized. 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