FI62961C - FOER FARING FOR FRAMSTARING AV KATJONUTBYTESMATERIALIER BETAOENDE AV ETT SYNTETISKT AMORF ALKALIMETALLALUMINIUMSILI KA - Google Patents

Abstract

The alumosilicates of the formula M2O.Al2O3.2.0 to 3.8 SiO2.XH2O, where M and X have the meanings specified in Claim 1, have an oil absorption of at least 75 ml/100 g, a BET area of at least 50 m<2>/g, a settling volume of more than 160.0 kg/m<3>, a void volume as determined by penetration with mercury of more than 2.0 ml/g, a base exchange capacity of at least 200 mg CaCO3/g and an initial water softening rate of 38.6 mg per litre per minute. Their primary particles are spherical and have a size of from 400 to 500 ANGSTROM . In order to prepare the alumosilicates (a) an at most 4-molar aqueous solution of an alkali metal silicate with an SiO2/M2O molar ratio of from 2.2 to 2.8 is prepared, (b) this solution is stirred vigorously in order to expose it to high shearing stress and turbulence, the solution reaching a linear velocity of from 91 to 122 m/min in the process, and at from 15 to 70 DEG C an at most 2-molar solution of an alkali metal aluminate having an M2O/Al2O3 molar ratio of from 1.2 to 2.8 is introduced slowly, (c) the reaction mixture thus formed is stirred further at a precipitation pH of at least 10.5 and (d) the precipitated finely disperse amorphous alkali metal alumosilicate is isolated. The alumosilicates are water softeners which can be used in detergents and cleaning agents.

Description

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Patent · och regiSterctyralMn '7 Anattkin utl »* d och utLskrMtwi pubUcurad 31.12. 82 (32) (33) (31) Pry4 «tty« tuolkuui —BufiH prlorltut 08.11.71 10.10.75 USA (US) 522375, 62131¾ (71) J.M. Huber Corporation, Thornall Street, Locust, Nev Jersey, USA (72) Lloyd Eugene Williams, Bel Air, Maryland, Robert Kenneth Mays,

Havre de Grace, Maryland, USA (US) (7¾) Oy Kolster Ab (5¾) Process for the preparation of cation exchange materials consisting of synthetic, amorphous alkali metal aluminosilicate aluminosilicates and the preparation of amorphous alkali metal aluminosilicates with highly enhanced cation exchange properties.

Cation exchange materials and their use in e.g. water softening are well known in the art. Although many products are known to have such properties, a particularly suitable class of ion exchangers is the so-called zeolites, which occur in nature per se or can be prepared synthetically. The structure of zeolites in crystalline aluminosilicate is based on the open three-dimensional backbone of SiO 2 and AlO 4 tetrahedra. Specific examples of synthetic zeolites, methods for their preparation as well as their use as ion exchangers, absorbents, and the like are described in U.S. Patent Nos. 2,882,243, 3,008,803, 2,962,355, 2,995,358, 3,010,789, 3,012,853, and 3,130,007.

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Other known cation exchange materials are cation exchange gels, which are granular products prepared by the reaction of sodium silicate and aluminum compounds. These products have been used to some extent in large-scale water softening to remove calcium and magnesium from water and can be regenerated by passing a NaCl solution through a filter layer of hard granules. See in this regard U.S. Patent Nos. 1,586,764, 1,717,777, 1,848,127 and GB 177,746.

In recent years, a large number of synthetic, amorphous, precipitated sodium aluminosilicate pigments have been manufactured and sold under the trademark "Zeolex". Examples of these products and methods of making them are disclosed in U.S. Patent Nos. 2,739,073 and 2,848,346. Such pigments have been found to be useful in a wide range of applications, such as fillers and reinforcing pigments for rubber compounds, plastics, paper and paper coating compositions, paints and adhesives, etc. Although such amorphous sodium aluminosilicate pigments have been found to be useful in such applications, the use of pigments as a cation exchange agent has hitherto been considered impractical due to their low exchange capacities.

Briefly, this invention relates to the preparation of synthetic, amorphous alkali metal aluminosilicates having elevated cation exchange properties and characteristics. As briefly stated above, while known amorphous aluminosilicate ion pigments are known to have ion exchange capacity, the products of this invention are superior in that they have about a two-fold increase in ion exchange capacity over known amorphous pigments and are equivalent or better than crystalline materials. such as the zeolites discussed above.

In its broadest sense, the high ion exchange capacity products of the invention are prepared by mixing and precipitating, under certain controlled conditions, dilute aqueous solutions of an alkali metal silicate such as sodium silicate and an alkali metal aluminate such as sodium aluminate. As used herein, the term alkali metal refers to Group Ia metals including sodium, potassium, lithium, cesium and rubidium. For convenience, sodium is hereinafter referred to.

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The process according to the invention contains carefully controlled precipitation conditions and as such is in stark contrast to the known crystallization, extraction and / or gelation technique. Critical precipitation conditions include the chemical composition and concentration of the reactants, the precipitation temperature and pH, the order and rate of addition of the reactants, and the intensity of agitation during precipitation. As for the composition of the reactants, the molar ratio of alkali metal to SiO 2 / O 2 should be 1-4 (M is an alkali metal). As discussed in more detail below, the composition and concentration of aluminate must be controlled to maintain maximum solubility and stability. The precipitation temperature is of the order of about 15-70 ° C and preferably 20-40 ° C. The pH of the precipitated mass must be kept above about 10.5. In carrying out the invention, the order of addition is critical to the extent that the reactants cannot simply be mixed as in known crystallization, gelling methods, but must be mixed together in such a way that the ratio of individual reactive ion species in the reaction zone or zone varies.

As mentioned, the products of the invention have a high and elevated ion exchange capacity. As such, they are particularly suitable for use in water softeners and detergents. In this respect, the additional advantages of the new products according to the invention are higher volume (lighter product), prevention of caking of the final product, lower adhesion of these products to the fabric, higher absorbency to non-ionic surfactants and better suspension in effluents (less settling).

It is a general object of the invention to provide a novel amorphous sodium aluminosilicate pigment having increased cation exchange capacity by precipitation by the reaction of alkali metal silicates and alkali metal aluminates under certain controlled process conditions.

Yet another object is to provide an amorphous aluminosilicate pigment for use in water softening, which is still particularly useful for use in detergents.

The manner in which the above and following objects of the invention are achieved will be better understood by reference to the following detailed description and drawings which form part of this specification of the invention and in which: Figures 4, 62 and 3 are micrographs of aluminosilicate ion exchangers in zeolite.

Figures 4, 5 and 6 are photomicrographs of amorphous precipitated sodium aluminosilicates prepared in accordance with the present invention.

As mentioned above, this invention relates to the preparation of amorphous sodium aluminosilicate pigments having enhanced cation exchange characteristics. In carrying out the invention, an amorphous product having a high ion exchange capacity is obtained by preparing an aqueous solution of alkali metal silicate and first passing this solution to a reactor or vessel equipped with stirring means. Heating means such as a steam jacket are also installed. The silicate should be such that its molar ratio SiO 2 / f 2 O is 2.2 to 2.8 (M is an alkali metal). The alkali silicate solution thus used should be about 4 molar or lower in concentration.

A dilute solution of an alkali metal aluminate such as sodium aluminate (if sodium silicate is used) is then slowly added to the silicate solution. Prior to the addition, the silicate solution is heated to a temperature between about 15 and 70 ° C. This temperature is maintained during precipitation. The concentration of the aluminate solution should be 2 molar or lower and preferably about 1 molar. The molar ratio of aluminate M 2 O / Al 2 O 2 (M is an alkali metal) should be about 1.2 to 2.8. In any case, the pH of the reaction mass must be kept above about 10.5 during the precipitation and preferably in the range of about 11-13.5. Vigorous stirring must be maintained throughout the reaction cycle, and this is especially important during the addition of dilute aluminate solution.

When the reaction procedure is completed, the precipitated pigment is usually separated from the reaction mixture by filtration, but other separation methods such as centrifugation can be used as well. In general, it is desirable to wash the freshly separated pigment with water to remove water-soluble salts and the like, after which the pigment can be dried to obtain a crumbly mass which is decomposed into a fine powder. The drying temperature of the precipitated pigment is important because excessive drying of the pigment lowers its exchange capacity.

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As mentioned, water-soluble sodium silicates and potassium silicates can be used in accordance with this invention, but much cheaper sodium silicates are naturally preferred. It is preferred to use a silicate having a SiO 2 / Na 2 O molar ratio of 2.2-2.8. Aluminates that can be used are commercially available and are well known in the art and are described, e.g., in U.S. Patent No. 2,882,243, or can be prepared by the reaction of an alkali metal oxide with reactive aluminas or aluminum hydroxides.

The products prepared according to the invention can be characterized as having a typical chemical composition of Na 2 O, N 2 O 2 .2. The primary particles of the newly invented amorphous product are spherical and generally in the range of 400-500 A. The primary particles associate into irregularly shaped and sized aggregates. These aggregates can be described as having a shape similar to "bunches of clusters." Aggregates tend to form loosely formed agglomerations that can be easily disintegrated by mechanical forces.

As mentioned above, the process for producing these products can be described as carefully controlled precipitations as opposed to the crystallization or extraction process associated with the preparation of crystalline products.

The essential differences in the physical properties of the known and manufactured products according to the invention are shown in Table I and the similarities in performance are easily apparent from the values in Table II.

The usefulness of these products as water softeners, where their cation exchange properties are obvious, can be evaluated by well-known methods used to determine calcium exchange capacity and exchange rates. For commercial use, the products should be able to exchange at least 250 mg CaCO 2 / g under test conditions and should be able to soften 80 mg / l (calcium hardness) hard water to 34 mg / l in one minute and 17 mg / l in 10 minutes. In this latter test, the cation exchanger is added at a concentration of 0,06% to hard water containing both calcium and magnesium with a hardness of 120 mg / l. The results in Table II show that the amorphous and semi-crystalline products are preferably comparable in performance to the crystalline product.

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Table III shows that excessive drying of the pigments of Examples I and II reduces the water hardness removal of this material and its ion exchange capacity.

The properties of the products of Examples III and IV are shown in Table IV. The effect of drying the pigment in light of its exchangeability is described using the product of Example IV in the form of a wet lump.

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Table II Performance values

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requirement Zeolite A product_ product_

Ca exchange capacity 250 261 282 280 (mg CaCo3 / g)

Ca removal rate Residual Ca hardness (mg / l) in 1 minute 34 7 12 15 in 10 minutes 17 1.7 3.8 3.4

Table III Product of Example I% Η301 CaCO 2 exchange capacity Ca removal rates _ mg / g pigment Residual Ca hardness (mg / l) 1 min. 10 min.

19.2 271 10.6 2.2 8.0 193 21 13 1.4 141 41 26

The product of Example II 19.1 293 17 2.6 8.4 200 24 15 1.4 133 63 51 contains bound water and other moisture in the pigment 9

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(ΛοΡΟΟϊΟΦυυυ dOdföPöO> 1 CO * 10 62961 Additional advantages of these products are higher volume, prevention of caking of the final product, lower adhesion of these products to the fabric, higher absorption capacity for non-ionic surfactants and better suspension in the effluent (less settling).

As briefly noted above, the uniquely high ion exchange capacity amorphous silicates of the invention are particularly useful for use in liquid or dry detergent compositions or detergent compounds.

In this regard, the silicates of the invention can be used with any conventional class of detergents, e.g. synthetic soap-free anionic, nonionic and / or amphoteric surfactants suitable as detergents.

The amount of ion exchange silicate required for use with the surfactant (active ingredient) may vary depending on the end use, the type of active ingredient used, pH conditions and the like. The optimum ratio of active substance / ion exchanger depends on the particular active substance used and the end use for which the detergent mixture is intended, but more usually the weight ratio of active substance / silicate ion exchanger is in the range of about 3: 1 to 1: 6.

The following examples further help to illustrate the invention.

Example I

An 83.6-liter reactor with reversible partitions and a turbine-type stirrer with 15.3 cm diameter vanes rotatable at 250 rpm. A dilute alkali silicate solution was prepared by dissolving 2.01 kg of sodium silicate (Na 2 O. 2.5 SiO 2) in 21 liters of water, and a dilute solution of sodium aluminate 1,6 Na 2 O / Al 2 O 2 was prepared by dissolving this in 4.76 kg of 16.9 liters of water. Silicate solution was charged to the reactor and the stirrer was started. The aluminate solution was then fed in a thin stream so that it hit the surface of the vigorously stirred liquid near the reactor wall. The addition of sodium aluminate solution was continued for 30 minutes. A total of 16.9 liters of solution was used. The temperature during the reaction was 50 ° C.

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Stirring of the reactive material was continued for 5 minutes and then the precipitate was filtered off and washed thoroughly with water. The resulting filter cake was dried at 110 ° C to obtain a crumbly cake which easily decomposed into a powder when pressed. This cake was passed once through a sieve mill from which the sieve had been removed in order to completely convert the agglomerated mass into a fine powder. The yield was 3.51 kg. The properties of the product are shown in Tables I and II.

Example II

The same procedure as in Example I was repeated except that stirring of the precipitated pigment was continued for 30 minutes before the pigment was separated by filtration and washing. The properties of this product are described in Tables I and II.

Example III

This example was carried out using the same equipment and procedure as described in Example I. The reactor was charged with a silicate solution prepared by dissolving 3.06 kg of sodium silicate having a composition of Na 2 O.2.4 SiO 2 in 31.4 liters of water, and an aluminate solution was prepared by dissolving 9.12 kg of sodium aluminate 2.6 Na 2 O / Al 2 O 61.2 liter of water. The resulting precipitate was then filtered off, dried and pulverized as described in Example I. The properties of this product are shown in Table IV.

Example IV

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

As used herein, the term "pigments" is not intended to be limited to dyes that impart color to other substances or mixtures, but is intended to refer to the fine, amorphous nature of the materials.

The magnifications of Figures 1-6 are 4,400X, 11,000X, 20,500X, 4,400x, 11,000X and 20,500X, respectively.

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All test values were obtained using well-known, standard and industry-accepted test methods. For example, oil absorption values were obtained according to ASTN-D281-31 (1966), introduced in 1931, re-approved in 1966, pH by ASTN-E70-68 (1973), surface area method by Bruner, Emmett, Teller, Jour. of Am.Chem. Soc., 60, 309-16 (1938), mercury intrusion by the method of 1958 ASTM Proc. Manual ASTM Bull. (1959) TP-49-54, density by compact method ASTM C493, 17, C373, 17, and cation exchange capacity and water softening rate according to DE application publication 2,412,837 (October 31, 1974).

Claims (1)

13 62961 Patent Method for preparing a finely divided, amorphous alkali metal aluminum silicate product having the following chemical composition: M2O.Al2O3.2.0-3.8 Sio2.XH2O, wherein M is an alkali metal, preferably sodium, and X has a value of 2 , 5-6.0, the product of which has an oil absorption of at least 75 cm / 100 g, a bulk density of more than 0.160 kg / dm, a BET surface area of at least 50 m / g, a mercury intrusion void of more than 3 2.0 cm / g and a cation exchange rate of at least 200 mg CaCO 2 / g, characterized by a combination of the following steps: a) preparing a 4 molar or more dilute aqueous solution of an alkali metal silicate with a molar ratio of SiO 2 / M 2 O of 2.2-2.8 and 2 molar, or a more dilute aqueous solution of alkali metal aluminate having a molar ratio of M 2 O / Al 2 O 3 of 1.2-2.8; b) the aqueous silicate solution is stirred vigorously to produce a high shear force and turbulence in the reaction mass and a linear velocity of 1.5-2.0 m / s; and an alkali metal aluminate solution is slowly introduced into this aqueous solution at a temperature of about 15 to 70 ° C, preferably 20 to 40 ° C. c) vigorously stirring the obtained reaction mass is continued by maintaining the pH of the reaction mass during precipitation at a value of at least more than 10.5, adding alkali if necessary to precipitate finely divided, amorphous alkali metal aluminum silicate; and d) recovering the alkali metal aluminosilicate precipitate by filtration and washing.