EP0368137B1 - Method for the preparation of high-density zeolite granules - Google Patents

Description

The present invention relates to a new production process for zeolite-containing granules with a pronounced adsorption capacity for liquid to waxy active substances. The granules are characterized by a high density, i. H. a bulk density between 750 and 1,000 g / l (grams per liter) and are suitable for use in detergents and cleaning agents.

From EP-A-243 908 granules are known which are used as water softening agents and which contain finely crystalline zeolite, sodium salts of polymeric or copolymeric carboxylic acids as well as sodium citrate and sodium carbonate. The granules were obtained by spraying an aqueous solution of the (co) polymeric salt onto a homogenized mixture of zeolite, citrate and carbonate. DE-A-33 16 513 discloses granules containing fine powdered zeolites and salts of (co) polymeric carboxylic acids which are produced by spray drying aqueous slurries. They have a bulk density of only 560 - 610 g / l. A teaching of the content that such granules can be used as carrier material for liquid to waxy detergent components is not to be found in this document. Granules which contain zeolites, salts of (co) polymeric carboxylic acids and additionally small amounts of alkali metal silicates and which serve as carrier material for liquid detergent components, in particular nonionics, are described in DE-A-34 44 960. The bulk density of these granules produced by spray drying is a maximum of 700 g / l and is preferably between 500 and 650 g / l. Document EP-A-149 264 teaches that commercially available spray-dried zeolites or mixtures thereof are used for the same purpose with inorganic salts such as sodium sulfate. The bulk density of these spray products is in the range of 400 - 600 g / l. From EP-A-21 267 agglomerates containing zeolites and alkali silicates are known which have a bulk density of 300-700 g / l. For their preparation, a dry premix of zeolite and alkali metal silicate (mixing ratio 1: 1 to 1: 8) is sprayed with water in a granulator and agglomerated, whereupon the excess water is removed to a residual proportion of less than 5% by weight by drying . The granules are also suitable for adsorbing liquid detergent components, in particular from Nonionics. The main disadvantage is their high content of strongly alkaline-reacting alkali silicates, which severely limits their use in neutral to weakly alkaline-reacting detergents suitable for sensitive textiles and furthermore reduces the proportion of zeolite which is capable of ion exchange. In addition, according to the teachings of this document, bulk densities of over 700 g / l cannot be achieved.

The present disadvantages are eliminated by the present invention and the production of granules with a high bulk density and a high proportion of ion-exchanging components is made possible.

The invention relates to a process for the production of granules containing fine crystalline zeolite, sodium or potassium salts of polymeric or copolymeric carboxylic acids and water, characterized in that (a) in a first mixing stage a homogeneous, powdery mixture of zeolite and the Salt of the (co) polymeric carboxylic acid, this mixture (b) agglomerated in a second mixing and granulation stage and (c) the agglomerate obtained until a good is reached free-flowing granules with a bulk density of 750-1000 g / l after-drying.

The granules which are produced by the process according to the invention generally contain (based on anhydrous substance) 60-80% by weight of zeolite, 2-15% by weight of a sodium salt of (co) polymeric carboxylic acids and 15-25% by weight. % Water, including water bound to the zeolite. In this case, an anhydrous zeolite is understood to be a sodium zeolite dewatered at the annealing temperature. Granules with a content of 62-75% by weight, in particular 65-70% by weight, of zeolite (calculated as anhydrous) and 4-12% by weight, in particular 5-10% by weight of Na salt (co- ) polymeric carboxylic acids (water content: difference up to 100% by weight) are preferred.

For the production of the granules, it is expedient to start with spray-dried, finely powdered zeolite, which generally has a water content of 17-25% by weight, preferably 19-22% by weight. This water includes constitutional water and adhering moisture. 70-95 parts by weight, preferably 75-93 parts by weight and in particular 80-90 parts by weight of this water-containing zeolite are mixed with 2-12 parts by weight, preferably 4-10 parts by weight and in particular 5-8 parts by weight of the sodium salt of the polymeric or copolymeric carboxylic acid combined to form a homogeneous powder mixture. For agglomeration, 15-25 parts by weight, preferably 18-23 parts by weight of water are mixed in with constant further mixing. The water is preferably sprayed onto the powder mixture kept in motion by means of nozzles, and this is further processed mechanically until granular agglomerates are formed.

The still moist but free-flowing agglomerate is then dried, for example with hot flowing air or with hot combustion gases, the drying being carried out until the water added in the granulation stage to a proportion of less than 5 parts by weight, preferably less than 3 parts by weight is removed. In addition, further water components that were originally introduced with the zeolite or a (co) polymeric salt which is not used anhydrous can be removed during drying. Such "over-dried" granules can have application advantages, for example when added to detergents that contain moisture-sensitive active ingredients. However, the dewatering of the zeolite should preferably not be driven below a water content of 18% by weight in order to avoid a reduction in activity. The water content of the granules is expediently in a range in which the water-binding capacity of the zeolite is largely saturated, i.e. H. in which the zeolite has a total water content of 19-22% by weight (including constitutional water).

Suitable zeolites are those of the zeolite A type. Mixtures of zeolite NaA and NaX can also be used, the proportion of the zeolite NaX in such mixtures advantageously being less than 30%, in particular less than 20%. Suitable zeolites have no particles larger than 30 µm and consist of at least 80% particles smaller than 10 µm. Their average particle size (volume distribution, measurement method: Coulter Counter) is 1 to 10 µm. Their calcium binding capacity, which is determined according to the information in DE-A-24 12 837 and is based on anhydrous substance, is in the range from 100 to 200 mg CaO / g.

Examples of the homopolymeric and / or copolymeric carboxylic acids contained in the granules, in the present case as water-soluble salts, of which the sodium salts are preferred, are also polyacrylic acid, polymethacrylic acid and polymaleic acid, copolymers of acrylic acid with methacrylic acid or maleic acid with vinyl ethers, such as vinyl methyl ether or vinyl ethyl ether with vinyl esters, such as vinyl acetate or vinyl propionate, acrylamide, methacrylamide and with ethylene, propylene or styrene. In those copolymeric acids in which one of the components has no acid function, the proportion thereof in the interest of sufficient water solubility is not more than 50 mole percent, preferably less than 30 mole percent. Copolymers of acrylic acid or methacrylic acid with maleic acid, as described in more detail in EP 25 551 B1, have proven to be particularly suitable. These are copolymers which contain 50 to 90% by weight of acrylic acid or methacrylic acid and 50 to 10% by weight of maleic acid. Copolymers in which 45 to 85% by weight of acrylic acid and 55 to 15% by weight of maleic acid are present are particularly preferred. The molecular weight of the homo- or copolymeric polycarboxylates is generally 2,000 to 150,000, preferably 5,000 to 100,000.

Commercially available salts of (co) polymeric carboxylic acids in powder form often contain 5 to 15% by weight of moisture. This proportion of water is included in the calculation of the water balance, or the amount of water introduced into the pelletizing stage can be reduced by this proportion. In mathematical terms, the proportion of salts in the preparation of the compositions or in the composition of the finished granules is based on anhydrous salt.

The granulation can be carried out batchwise or continuously in conventional mixing and granulating devices. Are suitable for. B. pelletizers, which consist of a horizontally arranged or inclined to the horizontal, cylindrical containers, in the longitudinal axis of which is equipped with a mixing tools and conveyor blades rotating shaft. The water can be supplied by spray nozzles mounted in the wall or on the hollow shaft. If work is carried out continuously, two consecutive mixers can be used, the dry premix being produced in the first mixer and the pelletizing taking place in the second mixer with the addition of water. Continuous work is also possible in a mixer, the powder streams being combined and homogenized in a first mixing section and the mixture being treated with water and agglomerating in a subsequent mixing section in a subsequent mixing section. The drying can be carried out by introducing hot gases in a third mixing section z. B. a fluidized bed, or after the granules have been discharged from the mixer, for example in a vibrating section, a free-fall dryer or in a thin layer on a conveyor belt. Finally coarse and fine particles are sieved. The coarse fractions are ground and mixed into the product, fine fractions or dust are returned to the granulation.

The granules have a bulk density of 750-1000 g / l, usually that of 800-950 g / l. Due to their tight packing and their small pore volume, their absorption capacity for liquid or pasty detergent components, especially nonionics, is somewhat reduced compared to specifically lighter carrier grains, but is still 15 to a maximum of 20% by weight without any appreciable impairment of the free-flowing properties. This In view of the high packing density, the surprisingly high adsorption capacity is completely sufficient for the usual fields of application, in particular for use as a mixture component in detergents and cleaning agents.

It is also surprising that, regardless of their high packing density and their high content of water-insoluble constituents, the granules disintegrate quickly and completely in cold water and do not leave any residues in the induction devices of washing machines, i. H. they have a very good induction ability. This advantageous property is also noticeable after impregnation with Nonionics and in a mixture with other powder detergent components.

The granules can be impregnated with any liquid or paste-like or fat-like detergent constituents which cannot be incorporated into conventional powdered or granular detergents or cleaning agents in other ways or only with a loss of activity. These include foam inhibitors, in particular paraffin hydrocarbons, silicones, silicone resins and bis-acylalkylenediamines derived from long-chain fatty acids, and mixtures thereof. Further adsorbable active ingredients are fatty acid alkylolamides and cationic plasticizers, such as quaternary ammonium salts containing long-chain fatty residues, and also fat-dissolving solvents, such as terpenes. The granules are preferably used as carrier grains for nonionic surfactants. This is another aspect of the invention.

Suitable nonionic surfactants are alkoxylation products with 10 to 20 carbon atoms in the hydrophobic radical and 3 to 20 glycol ether groups. These include ethoxylation products of alcohols, vicinal diols, amines, thio alcohols, fatty acid amides and fatty acids. Alkylphenol polyglycol ethers with 5 to 12 carbon atoms in the alkyl radical and 3 to 10 ethylene glycol ether groups are also useful. Block polymers of ethylene oxide and propylene oxide, which are commercially available under the name Pluronics, are also suitable. Alkyl glycosides or alkyl polyglycosides and mixtures thereof with the ethoxylation products mentioned can also be used.

Preferred nonionics, which can be adsorbed on the granulate and together with it as a free-flowing mixture, are derived from alcohols with 12 to 18 carbon atoms which are saturated or olefinically unsaturated, linear or methyl-branched in the 2-position (oxo radical) could be. Their reaction products with ethylene oxide (EO) or propylene oxide (PO) are water-soluble or water-dispersible mixtures of compounds with different degrees of alkoxylation, the number of EO or PO groups given below corresponding to a statistical mean.

Examples of preferred ethoxylated fatty alcohols are C₁₂₋₁₈ coconut alcohols with 3 to 12 EO, C₁₆₋₁₈ tallow alcohol with 4 to 16 EO, oleyl alcohol with 4 to 12 EO and ethoxylation products of corresponding chain and EO distribution available from other native fatty alcohol mixtures. From the series of ethoxylated oxo alcohols, for example, those of the composition C₁₂₋₁₅ + 5 to 10 EO and C₁₄₋C₁₅ + 6 to 12 EO are suitable. Mixtures of low and highly ethoxylated alcohols are distinguished by an increased detergency against both greasy and mineral stains, for example those from tallow alcohol + 3 to 6 EO and tallow alcohol + 12 to 16 EO or C₁₃₋₁₅-oxo alcohol + 5 EO and C₁₂₋₁₄ oxo alcohol + 8 to 12 EO. Furthermore, ethoxylates are also suitable which contain EO groups and PO groups, e.g. B. C₁₂₋₁₈ alcohols of the formula R- (PO) _a - (EO) _b or R- (EO) _b - (PO) _c , wherein a numbers from 1 to 3, b such from 5 to 20 and c mean those from 1 to 10 (b greater than c).

The liquid, optionally heated, additives, in particular nonionics, can be applied to the granules by mixing, preferably spraying, the carrier material advantageously being kept in motion by suitable mixing devices. Further treatment of the granular adsorbate is not necessary. However, leaving the product to rest for several hours at high contents of applied liquid material can be expedient, since its diffusion into the interior of the grain takes some time. The treatment of the granules with the liquid additives leads to a further increase in the bulk density, which can rise to values of over 1,000 g / l.

After the liquid additive has been applied, the grains can optionally be dusted with finely divided powders or coated on the surface. As a result, the free-flowing properties can be improved and the bulk weight increased slightly, if the nonionics content exceeds 15%. Suitable powdering agents have a grain size of 0.001 to at most 0.1 mm, preferably less than 0.05 mm and can be present in proportions of 0.03 to 3, preferably 0.05 mm to 2% by weight, based on the Additive-laden adsorbents can be used. For example, finely powdered zeolites, silica airgel (Aerosil ^(R) ), colorless or colored pigments such as titanium dioxide are suitable. in the in general, however, such an aftertreatment is superfluous, especially since it does not improve the solution properties.

The detergent additives can be combined and mixed in a known manner with the granular or pulverulent detergent, for example a tower spray powder and its mixtures with other powder components, such as persalts, enzyme granules, bleach activators or defoamers. The high bulk density and the favorable flushing behavior of the additives according to the invention are transferred to these complex mixtures. In practice, the detergents mixed together generally contain 10 to 40% by weight of the additive according to the invention.

The granules according to the invention have a different grain structure than those which are produced by conventional granulation processes. This can also be demonstrated by electron micrographs. If, as is customary in conventional granulation processes, the powdery zeolite is placed in the mixer and a solution of the (co) polymeric salt is sprayed on, granules are formed which do not differ externally from the products according to the invention, except that their bulk density is significantly reduced. The images obtained with the scanning electron microscope show sections through two different granules on a magnification scale of 1: 2 500 (Figs. 1 and 2) and 1: 5 000 (Figs. 3 and 4). Both grains have the same qualitative and quantitative composition as in Example 1. Figures 1 and 3 show a grain, in the production of which the spray-dried zeolite was sprayed in a mixer with a 25% strength by weight aqueous solution of the copolymeric salt, granulated and then dried. Figures 2 and 4 show the grain structure of the according to the information from Example 1 manufactured product. The arrangement of the cubic zeolite particles in Figures 1 and 3 is completely random. Large pores change with strongly glued, irregularly structured aggregates. In Figures 2 and 4, the zeolite cubes are packed much denser and more uniformly. Individual parts are reminiscent of a structure comparable to a pavement or a brickwork. The pore size is also significantly reduced.

example 1

The granulation was carried out in a mixing granulator, consisting of a horizontally arranged cylindrical mixer with a rotating shaft (Lödige type) rotating in the central axis, equipped with mixing elements, with a capacity of 130 liters and a knife mill connected to it, operated at a speed of 1200 to 1500 rpm . In the mixing granulator, 69.5 parts by weight of a synthetic, finely crystalline, spray-dried zeolite of the NaA type, containing 20% by weight of bound water, were mixed with 8.8 parts by weight of the powdered sodium salt of an acrylic acid-maleic acid copolymer (moisture content 8 % By weight) to a homogeneous powder mixture. The copolymer (Sokalan ^(R) CP5 from BASF, Ludwigshafen) had a molecular weight of approximately 70,000. After the mixing, which took about 20 seconds, 21.7 parts by weight of water were sprayed in over 90 seconds by means of nozzles and the mixture was granulated for a further 3 minutes with constant mixing. The granules leaving the mixer were dried in a fluidized bed with hot, flowing dry gases. The final product had the following composition:
72.9% by weight of zeolite (calculated as anhydrous)
9.3% by weight polymer salt (calculated anhydrous)
17.8 wt% water
The water was practically completely bound to the zeolite, from which a water content of the zeolite of 19.7% by weight is calculated. After screening about 15% coarse grain, a sieve analysis showed the following grain distribution (the amount in% by weight remaining on the sieves is given): m 1.6 0.8 0.4 0.2 0.1 less than 0.1 % By weight 20th 29 23 14 8th 6

The bulk density of the granules was 900 g / l.

The granules were sprayed in a spray mixer with a liquid, nonionic surfactant heated to 40 ° C., consisting of a mixture of coconut and tallow alcohol reacted with 5 mol EO in a ratio of 1: 4. After a standing time of 1 hour, the adsorbates showed the following bulk weights: example % By weight nonionic g / l bulk density 1a 2nd 960 1b 6.5 995 1c 12.3 1,060

The granules treated with the nonionic surfactant were free-flowing and had a perfect wash-in capacity, both as unblended powder and mixed with a powdery household detergent in a ratio of 1: 4.

Claims (7)

1. A process for the production of granules containing finely crystalline zeolite, sodium or potassium salts of polymeric or copolymeric carboxylic acids and water, characterized in that (a) a homogeneous, powder-form mixture of zeolite and the salt of the (co)polymeric carboxylic acid is prepared in a first mixing step, (b) the mixture thus prepared is agglomerated in a second mixing and granulation step and (c) the agglomerate obtained is dried until free-flowing granules having an apparent density of 750 to 1,000 g/l are obtained.
2. A process as claimed in claim 1, characterized in that the granules produced contain (based on anhydrous substance) 60 to 80% by weight zeolite, 2 to 15% by weight of the sodium salt of the (co)polymeric carboxylic acid and 14 to 25% by weight water, including the water bound to zeolite.
3. A process as claimed in claim 1, characterized in that the granules produced contain (based on anhydrous substance) 62 to 75% by weight and more especially 65 to 70% by weight zeolite and 4 to 12% by weight and more especially 5 to 10% by weight sodium salt of (co)polymeric carboxylic acids.
4. A process as claimed in claim 1 and claim 2 or 3, characterized in that 70 to 95 parts by weight of a spray-dried, finely powdered zeolite containing 15 to 25% by weight and preferably 18 to 22% by weight bound water, including water of constitution, and 3 to 12 parts by weight of a sodium salt of (co)polymeric acids are homogeneously mixed, the resulting mixture is agglomerated in the presence of 15 to 25 parts by weight water and the water introduced in the granulation step (b) is removed by subsequent drying to a residual content of less than 5 parts by weight and preferably less than 3 parts by weight.
5. Granules obtainable by the process claimed in one or more of claims 1 to 4 impregnated with up to 20% by weight (based on adsorbate) of at least one liquid, paste-form or fatty detergent ingredient.
6. Granules as claimed in claim 5, characterized in that the impregnating agent consists of nonionic surfactants.
7. The use of the granules obtainable by the process claimed in one or more of claims 1 to 4 or the granules claimed in claim 5 or 6 as a powder component in detergents and cleaning preparations.

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