CH620659A5 - Process for preparing finely disperse, amorphous, pigment-like alkali metal alumosilicates - Google Patents

Description

The present invention relates to a method for producing finely divided amorphous pigment-shaped alkali metal aluminosilicates, in particular sodium aluminosilicates, which are defined in claim 1.

Materials with interchangeable cations and their use e.g. B. in softening water are well known to those skilled in the art. Although it is known that many products have such properties, the so-called zeolites, which occur naturally or can be produced synthetically, generally represent a particularly suitable class of ion exchangers. Structurally, aluminosilicate zeolites basically consist of an open, three-dimensional network of Si04- and A104 tetrahedra. Specific examples of synthetic zeolites, processes for their preparation and their use as ion exchangers, adsorbents and the like. The like are described in U.S. Patent Nos. 2,882,243, 3,008,803, 2,962,355, 2,996,358, 3,010,789, 3,012,853 and 3,130,007. Other known base exchange materials are base exchange gels, which are granular products made by the reaction of sodium silicate with aluminum compounds. These products have been used to some extent to soften water on a large scale by removing calcium and magnesium from water and can be regenerated by passing a sodium chloride solution through a filter bed from the hard grains. In this regard, reference is made to U.S. Patent Nos. 1,586,764, 1,717,777 and 1,148,127, and British Patent No. 177,746.

In recent years, a number of synthetic, amorphous, precipitated sodium aluminosilicate pigments have been produced, which are marketed under the brand name “Zeolex”. The term “pigments” is not used here and in the following to refer to coloring materials that give color to other substances or mixtures, but refers to the finely divided, amorphous nature of the materials. Examples of such synthetic, amorphous, precipitated sodium aluminosilicate pigments and processes for their preparation are described in US Pat. Nos. 2,739,073 and 2,848,346. Such pigments have been found to be useful for a wide range of applications, e.g. B. as fillers and reinforcing pigments for rubber mixtures, plastics, paper and paper coating compositions, paints, adhesives etc. While such amorphous sodium aluminosilicate pigments have proven to be useful for such purposes, their use as base or ion exchange products has hitherto been considered impractical because of their low exchange capacity .

DE-OS No. 1 717 158 and the corresponding FR-PS No. 1 572 147 describe the production of finely divided, predominantly amorphous sodium aluminum silicates, the specific surface area and bulk density of which is similar to that of the present aluminosilicates. The reactants are added in the same order as in the process according to the invention, but neither the concentrations used according to the invention, the molar ratios Si02: M20 or M20: A1203 and stirring speeds are used, nor was it recognized that the products are suitable for softening water and are useful in detergents and cleaning agents.

GB-PS No. 1 232 429 (and the corresponding DE-AS No. 1 667 620) also describe the preparation of sodium aluminum silicates, but with an aqueous sodium silicate solution being added to a vigorously stirred sodium aluminate solution.

BE-PS No. 813 561 describes water hardness formers binding, optionally bound water-containing compounds of the formula

(Cat2 / nO) x, Me203. (Si02) y in which Cat means an n-valent cation that can be exchanged for calcium. Me is boron or aluminum, x stands for 0.7 to 1.5 and y stands for 0.8 to 6.

The present invention relates to the production of synthetic amorphous alkali metal aluminosilicates, in particular sodium aluminosilicates, which have improved ion or base exchange properties. As already briefly mentioned above, it is known that amorphous aluminosilicate pigments according to the prior art (as described in US Pat. No. 2,739,073) have ion exchange capacity, but the products according to the invention are the products according to the prior art superior in that their ion exchange capacity is increased two to five times that of known amorphous pigments and is equal to or better than that of known crystalline materials such as the zeolites discussed above.

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The amorphous products according to the invention with a high ion exchange capacity are generally produced by mixing and precipitating dilute aqueous solutions of an alkali metal silicate, such as sodium silicate, and an alkali metal aluminate, such as sodium aluminate, under the conditions specified in claim 1. The term “alkali metal” in this description refers to metals from group la and includes sodium, potassium, lithium, cesium and rubidium. For the sake of simplicity, only sodium is referred to below.

The process according to the invention comprises carefully controlled precipitation conditions and is therefore in direct contrast to known crystallization, digesting and / or gelling methods. Critical precipitation conditions include the chemical composition and concentration of the reactants, the precipitation temperature and pH, the order (and preferably also the rate of addition) of the reactants and the intensity of mixing during the precipitation. As for the composition of the reactants, the alkali metal silicate has a Si02: M20 molar ratio of 2.2 to 2.8. The composition and concentration of the aluminum, as will be discussed in more detail below, must be controlled in order to maintain maximum solubility and stability. The precipitation temperature is of the order of 15 to 70 ° C., preferably 20 to 40 ° C. The pH of the precipitation mass must be kept at least 10.5. In the practical implementation of the invention, it is advantageous that the reactants are not simply mixed as in known crystallization, digesting and gelling processes, but are mixed in such a way that the amount of the individual reactive ion species in the reaction zone is within a predetermined concentration range lie.

As already stated, the products according to the invention have a high and improved ion or base exchange capacity. As such, they are particularly suitable for use in softening water and in detergents. In this regard, there are additional advantages of the new products in the greater "bloating" (lighter product), the improvement of the finished product by preventing caking, the lower deposition or storage of these products in textile fabrics, the higher absorption capacity for nonionic surfactants and the better suspendability in water used for draining (less settling).

The main aim of the invention is to provide a novel amorphous alkali metal aluminosilicate pigment, in particular sodium aluminosilicate pigment, with improved ion or base exchange properties, and a method for the precipitation of amorphous aluminosilicates with high ion or base exchange capacity by reacting alkali metal silicates with alkali metal aluminates controlled by alkali metals To provide process conditions, wherein the amorphous alkali metal aluminosilicate pigment, in particular sodium aluminosilicate pigment, is suitable for use in softening water and can be used in particular in washing and cleaning agents.

The invention will now be explained with reference to the drawing; in the drawing are:

1, 2 and 5 are micrographs of known crystalline zeolitic aluminosilicate exchangers made in accordance with the teachings of U.S. Patent No. 2,882,243;

3, 4 and 6 microphotographs of the amorphous precipitated sodium aluminosilicates produced according to the invention.

As already stated above, the present invention relates to the production of amorphous alkali metal

mosilicate pigments, especially sodium aluminosilicate pigments. with improved base and ion exchange properties. According to a preferred embodiment of the invention, the amorphous product with high ion exchange capacity is produced by preparing an aqueous solution of an alkali metal silicate and first introducing this solution into a reaction vessel which is provided with a stirring device and a heating device such as a steam jacket. The silicate must have a molar ratio of Si02: M20 of 2.2 to 2.8. The concentration of the alkali metal silicate solution used in this way must be 4 molar or less. Thereafter, a dilute solution of an alkali metal aluminate, such as sodium aluminate (when using sodium silicate), is slowly introduced into the silicate solution, which has previously been heated to a temperature between 15 and 70 ° C. This temperature is maintained during the precipitation. The concentration of the aluminate solution must be 2 molar or less, preferably about 1 molar. The aluminate must have a molar ratio of M20: A1203 from 1.2 to 2.8. In any case, the pH of the reaction mass must be kept at least 10.5, preferably in the order of 11 to 13.5, during the precipitation. A high mixing intensity must be maintained throughout the reaction time, which is particularly important during the addition of the dilute aluminate solution.

After completion of the reaction, the precipitated pigment is usually separated from the reaction liquid by filtration, but other separation methods such as centrifugation can also be used. In general, it is desirable to wash the freshly separated pigment with water to remove water-soluble salts and the like. Remove the like, after which it can be dried to give a crumbly mass which easily disintegrates into a fine powder. The temperature used to dry the precipitated pigment is important because excessive drying of the pigment reduces its exchange capacity.

As already mentioned, water-soluble sodium silicates and potassium silicates can be used according to the invention,

but the much less expensive sodium silicates are of course preferred. The aluminates that can be used are commercially available and known to the person skilled in the art, e.g. From U.S. Patent No. 2,882,243, or they can be made by reacting the alkali metal oxide with reactive aluminum oxides or aluminum hydroxides.

The products according to the invention are characterized by their typical chemical composition, that for M = Na of the empirical formula:

Na20 • A1203 • 2.0 to 3.8 Si02 • X H20

corresponds, in which X can assume values from 2.5 to 6. The primary particles of the newly developed amorphous product are spherical and have dimensions in the range of 400 to 500 angstrom units. The primary particles combine to form permanent aggregates with irregular shapes and sizes. The aggregates have a shape similar to "grapes" and their size is in the range of 2000 to 5000 angstrom units. The aggregates have a tendency to form agglomerates with a loose structure that can be easily dismantled by mechanical forces.

As previously stated, the process for making these products, as opposed to the crystallization or digesting process used in the manufacture of crystalline products, can be called a carefully controlled precipitation.

Significant differences in the physical properties of different products are summarized in Table 1, while similarities in behavior

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are readily apparent from the data presented in Table II.

The usefulness of these products as a means of softening water due to their obvious base exchange properties can be assessed according to known methods for determining the calcium exchange capacity and the calcium exchange rate. For technical purposes, the products should be able to exchange at least 250 mg calcium carbonate per gram under the test conditions and hard water with a calcium hardness of 67.2 mg / liter (4.7 gr./gal.) To 28.6 mg / gal in 1 minute. Liter (2.0 gr./gal.) And can be reduced to 14.3 mg / liter (1.0 gr./gal.) In 10 minutes. In this last-mentioned test, the base exchanger is added to hard water with a mixed calcium / magnesium hardness of 100.1 mg / liter (7.0 gr./gal.) In an amount of 0.06%. The results in Table II show that the amorphous and semicrystalline products perform favorably in comparison with the crystalline product with regard to the use behavior.

5 Table III shows that excessive drying of the pigments from Examples 1 and 2 reduces the depletion capacity and the exchange capacity of the material. The loss on ignition comprises bound water plus any moisture that may be present in the pigment.

The properties of the products of Examples 3 and 4 are summarized in Table IV. The effect of drying the pigment on its exchange capacity is shown by comparison with the use of the product of Example 4 in the form of a wet cake.

Table I

properties

Zeolite A (USP 2,882,423)

Product of Example 1

Product of Example 2

% crystalline form A according to X-ray diffraction BET surface area (m2 / g)

Oil absorption (ml / 100 g)

Bulk density (pour density)

kg / m3 (lbs / ft3)

Ramming volume (pack density)

kg / m3 (lbs / ft3)

Hg penetration (ml / g)

pH (1%)

% Alkalinity (% Na20)

Particle size *:

10% by weight less than 20% by weight less than 30% by weight less than 40% by weight less than 50% by weight less than 60% by weight less than 70% by weight less than 80% by weight less than 90% by weight .% less than

100 3 25

312.0 (19.5)

555.2 (34.7)

1.03 11.0

1.2

3.5 a 5.0 fi

6.4 fi

7.3 fi 1.9 fi 8.4, «

9.0 fi

10.4 fi 22.0 fi

Amorphous 96 149

147.2 (9.2)

294.4 (18.4) 2.83 10.6 0.2

1.4 fi 2.6 fi

3.5 fi 5.0 u 6.4 fi 8.0, «

9.8 fi

VI fi fi 15.5, il

Amorphous 90 145

144.0 (9.0)

284.8 (17.8) 2.89 10.7 0.2

1.3 «

2.4 fi 3.4 fi 4.7 //

6.0 fi 73 fi 9.0 u

11.0 M 13.5 «

Chemical composition:

çf h2o

% Na20% A1203% Si02

Sum Si02 / Al203

20.9 17.7

26.7

35.8

101.1 2.28

19.2 14.2 25.4 40.9

99.7 2.74

19.1 14.5

26.4

39.5

99.5 2.54

* Determined with devices from Mine Safety Appliance (USA).

Table II Use behavior

Properties minimum zeolite A product of product of requirements Example 1 Example 2

Ca exchange capacity (mg CaC03 / g) 250 261 282 280

Ca depletion rate,

remaining Ca hardness, mg / liter (gr./gal.)

after 1 minute <28.6 (<2.0) 5.86 (0.41) 10.44 (0.73) 12.87 (0.90)

after 10 minutes <14.3 (<1.0) 1.43 (0.1) 3.15 (0.22) 2.86 (0.20)

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Table III

c <r loss on ignition (pi LOI)

CaC03 exchange capacity (mg / g «pigment»)

Ca depletion rate, remaining Ca hardness, mg / liter (gr./gal.) After 1 min. After 10 min.

19.2 8.0 1.4

19.1

Product of Example 1 271 8.87 (0.62)

193 17.2 (1.2)

141 34.3 (2.4)

Product of Example 2 293 14.3 (1.0)

1.86 (0.13) 10.58 (0.74) 22.9 (1.6)

2.29 (0.16)

8.4 200

20.0 (1.4)

12.58 (0.88)

1.4 133

52.9 (3.7)

42.9 (3.0)

Table IV

properties

Product of

Product of

Product of

Example 3

Example 4

Example 4

(as wet

Cake, un

dried)

% crystalline form A

according to x-ray

diffraction

Amorphous

Amorphous

Amorphous

BET surface

(m2 / g)

102

105

oil absorption

(ml / 100 g)

145

148

Penetration from Hg

2.70

2.49

Ca exchange

capacity

(mg CaCCVg)

202

234

350 ^ 00

Ca depletion

speed,

remaining Ca hardness,

mg / liter (gr./gal.)

after 1 minute

37.2 (2.6)

12.16 (0.85)

after 10 minutes

3.86 (0.27) 1.57 (0.11)

% Loss on ignition

(% H20)

20.5

19.21

83.9

% Na20

18.05

% ai2o3

25.30

% Si02

36.13

total

98.69

Si02 / AM),

2.43

As already briefly noted above, the amorphous silicates according to the invention are particularly suitable for use in liquid or dry detergents or cleaning agents because of their uniquely high ion exchange capacity. For this purpose, the silicates according to the invention can be used in combination with detergents from any of the conventional classes, i.e. H. with synthetic anionic, nonionic and / or amphoteric surface active compounds that are not soaps and are suitable cleaning agents. Anion-active surface-active compounds can be generally defined as compounds which contain hydrophilic or lyophilic groups in the molecule and are ionized in an aqueous medium, the anions containing the lyophilic group being formed. These compounds include sulfated or sulfonated aliphatic, aromatic and alkyl aromatic Koh10

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hydrogen and their alkali metal salts, for. B. the sodium salts of long-chain alkyl sulfuric acids, the sodium salts of alkylnaphthalenesulfonic acids, the sodium salts of sulfonated abietins, the sodium salts of alkylbenzenesulfonic acids, especially those whose alkyl group contains 8 to 24 carbon atoms, the sodium salts of sulfonated mineral oils and the sodium salts of sulfosuccinic acid, such as sodium dioctyl sulfosuccinate.

Advantageous anionic surfactants are the higher alkyl aryl sulphonic acids and alkali metal and alkaline earth metal salts such as Natriumdodecylben-zolsulfonat, Natriumtridecylbenzolsulfonat, Magnesiumdode-cylbenzolsulfonat, Kaliumtetradecylbenzolsulfonat, Ammo-niumdodecyltoluolsulfonat, Lithiumpentadecylbenzolsulfonat, Natriumdioctylbenzolsulfonat, Dinatriumdodecylbenzoldi-sulfonate, Dinatriumdiisopropylnaphthalindisulfonat u. Like., And the alkali metal salts of fatty alcohol esters of sulfuric and sulfonic acids, the alkali metal salts of alkylarylsulfothiocarboxylic acid esters and alkylthiosulfuric acids, etc.

Noniogenic surfactants can be broadly defined as compounds that are not ionized, but usually assume hydrophilic properties due to an oxygen-containing side chain, such as a polyoxyethylene chain, while the lyophilic portion of the molecule can be derived from fatty acids, phenols, alcohols, amides or amines. Examples of nonionic surfactants are condensation products of one or more alkylene oxides with 2 to 4 carbon atoms, such as ethylene oxide or propylene oxide, preferably ethylene oxide alone or in a mixture with other alkylene oxides, and a relatively hydrophobic compound, such as a fatty alcohol, a fatty acid, a sterol, one Fatty acid glyceride, a fatty amine, an arylamine, a fatty mercaptan, tall oil, etc. The nonionic surface-active agents also include condensation products from one or more alkanolamines with a relatively low alkyl radical, such as methanolamine, ethanolamine, propanolamine etc., and a fatty acid such as lauric acid, cetyl acid, Tall oil fatty acid, abietic acid, etc., d. H. the corresponding amides.

Particularly advantageous nonionic surface active agents are condensation products of a hydrophobic compound with at least one active hydrogen atom and a lower alkylene oxide, e.g. B. the condensation product of an aliphatic alcohol with about 8 to 18 carbon atoms and about 3 to 30 moles of ethylene oxide per mole of the alcohol or the condensation product of an alkyl phenol with about 8 to 18 carbon atoms in the alkyl group and about 3 to 30 moles of ethylene oxide per Moles of alkyl phenol. Other nonionic detergents are condensation products of ethylene oxide with a hydrophobic compound formed by the condensation of propylene oxide with propylene glycol.

Amphoteric surface-active compounds can be generally defined as compounds which contain both anionic and cationic groups in the same molecule. Such compounds can be categorized depending on the type of the anion-forming group, which is usually carboxyl, sulfo or sulfato. Examples of such compounds are sodium N-coconut / i-aminopropionate, sodium trium-N-tallow / 3-aminodipropionate, sodium N-lauryl-y3-imino-dipropionate and the like. the like

Other typical examples from these categories of anionic, nonionic and / or amphoteric surfactants are found in "Surface Active Agents" by Schwartz and Perry, Interscience Publishers, New York (1949) and Journal of American Oil Chemists Society, Vol. 34, No. 4, pp. 170 to 216 (April 1957).

The amount of exchange silicates in combination

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to be used with the surfactant depends on the intended use, the type of surfactant used, the pH conditions and the like. Like. The optimal ratio of surface-active compound to ion exchanger depends on the specific surface-active compound used and the intended use for which the washing or. Detergent is determined, but the weight ratio of surface-active compound to silicate exchanger is generally in the range of about 3: 1 to 1: 6.

The following examples illustrate the invention.

example 1

A 113.6 liter reaction vessel (30 gallon reaction vessel) provided with baffle plates was equipped with a turbine stirrer, the blades of which had a diameter of 152.4 mm (6 inches) and which was rotating at 250 revolutions per minute was able to. A 0.454 molar alkali metal silicate solution was prepared by using 2.018 kg (4.45 lbs.) Sodium silicate of the formula:

Na20-2.5 Si02

dissolved in 20.971 liters (5.54 gals.) of water, while a limolar solution of sodium aluminate of the formula:

1.6 Na20 / Al203

was prepared by dissolving 4.7.5 kg (10.5 lbs.) of sodium aluminate in 16.883 liters (4.46 g.) of water. The reaction vessel was charged with the silicate solution and the stirrer started up. The aluminate solution was then added in a thin stream so that it struck the surface of the vigorously stirred liquid near the wall of the reaction vessel. The addition of the sodium aluminate solution was continued for 30 minutes. A total of 16.883 liters (4.46 gals.) Of the solution was used. During the reaction the temperature was 50 ° C. The reaction mixture was stirred for a further 5 minutes, after which the precipitate was separated by filtration and washed thoroughly with water. The resulting filter cake was dried at 110 ° C to obtain a crumbly cake that easily disintegrated into a powder when compressed. This cake was passed through a sieve hammer mill with the sieve removed to completely convert the agglomerated mass into a fine powder. The yield was 3.515 kg (7.75 lbs.). The properties of the product are given in Tables I and II.

Example 2

The procedure of Example 1 was repeated, but stirring continued for 30 minutes after the pigment was precipitated before the pigment was separated by filtration and washed. The properties of this product are given in Tables I and II.

Example 3

This example was carried out using the same device and procedure as in Example 1. The reaction vessel was charged with a 0.123 molar silicate solution which was prepared by dissolving 3.062 kg (6.75 lbs.) Of sodium silicate having the composition Na20-2.4 Si02 in 31.419 liters (8.3 gallons) of water while preparing a 0.585 molar aluminate solution by dissolving 9.435 kg (20.8 lbs.) of sodium aluminate having the composition 2.6 Na20 / Al203 in 61.324 liters (16.2 gallons) of water. The precipitate formed was filtered off as described in Example 1, dried and pulverized. The properties of this product are given in Table IV.

Example 4

The procedure of Example 3 was repeated. The only difference was that the reaction temperature was lowered to 25 ° C.

Example 5

The general procedures of Examples 1 and 2 were repeated, but using silicates with molar ratios of SiO2: Na20 from 2.2 to 2.8 and aluminates with molar ratios of Na20: A1203 from 1.2 to 2.8 instead of those in Examples 1 and 2 raw materials used were used. It was found that by changing the molar ratios of the oxides, products with an oil absorption of at least 75 ml / 100 g and BET surface areas of at least 50 m2 / g could be produced. The voids found by the penetration of mercury were more than 2.0 ml / g. The base exchange capacities were at least 200 mg CaC03 / g. The water softening rates were on the order of 38.6 mg per liter (2.7 grains per gallon) per minute.

As already mentioned, the term “pigments” is not intended to denote coloring materials that give color to other substances or mixtures, but refers to the finely divided, amorphous nature of the materials. The enlargements of FIGS. 1 to 6 are 4400 times, 11 times, 4400 times, 11 times, 20 500 times and 20 500 times, respectively.

All test data were determined according to known, standardized test methods used in industry. For example, the oil absorption values were adopted according to ASTM-D281-31 (1966), adopted in 1931, Reapproved in 1966, the pH values according to ASTM-E70-68 (1973), the BET surface area according to the method of Brunauer, Emmett and Teller , Jour. At the. Chem. Soc. 60, 309 to 316 (1938), the penetration of mercury (mercury intrusion) according to the method of 1958 ASTM Proc. Manual ASTM Bull. (1959) TP-49-54, the tamped volume (pack density) according to ASTM C493, 17, C373, 17 and the base exchange capacity and the rate of water softening according to German Offenlegungsschrift No. 2 412 837 (October 31, 1974) .

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Claims (4)

620 659 1. Process for the preparation of finely divided amorphous pigment-shaped alkali metal aluminosilicates suitable for softening water and usable in detergents and cleaning agents, of the formula M20 • A1203 • 2.0 to 3.8 Si02 - X H20, in which M denotes an alkali metal and X has a value of 2.5 to 6, which has an oil absorption of at least 75 ml / 100 g, a BET surface area of at least 50 m2 / g, a tamped volume of more than 160.0 kg / m3, a value determined by the penetration of mercury Have void volumes greater than 2.0 ml / g, a base exchange capacity of at least 200 mg CaC03 / g, and an initial water softening rate of 38.6 mg per liter per minute and whose primary particles are spherical and have a size in the range of 400 to 500 Angstrom units have characterized in that a) an aqueous solution of an alkali metal silicate with a molar ratio of SiO 2 to M 20 of 2.2 to 2.8 is produced, the concentration of which is 4 molar or less t, b) the aqueous solution is stirred vigorously, subjecting it to high shear stress and turbulence and giving it a linear velocity of 91 to 122 m per minute, and slowly adding a solution of an alkali metal solution to the alkali metal silicate solution at a temperature of 15 to 70 ° C. introduces aluminates with a molar ratio of M20 to A1203 from 1.2 to 2.8, the concentration of which is 2 molar or less, c) stirring the reaction mass formed by adding the alkali metal aluminate solution to the alkali metal silicate solution while maintaining the pH of the reaction mass at a value of at least 10.5 during the precipitation to thereby precipitate the finely divided amorphous alkali metal aluminosilicate, and d) the alkali metal aluminosilicate wins. 2. The method according to claim 1, characterized in that M is sodium. 2nd claims 3. The method according to claim 2, characterized in that slowly adding the aqueous sodium aluminate solution at a temperature of 20 to 40 ° C to the aqueous sodium silicate solution. 4. A detergent containing synthetic detergent, characterized in that it contains an alkali metal aluminosilicate produced by the process according to claim 2 as ion or base exchanger and water softening agent.