EP0179264B1 - Process for the production of a granular free-flowing washing compound - Google Patents

Abstract

A process for the production of a granular, free-flowing detergent composition which is rapidly soluble in water, and the product thereof which has a bulk density of at least 600 g/l and a particle size of 0.1-2 mm, wherein an aqueous slurry of the composition ingredients is continuously homogenized to yield a viscosity of 4,000 to 20,000 mPa.s and heated to a temperature of 85 DEG -105 DEG C. The homogenized heated slurry is then sprayed in a drying tower through nozzles having a bore diameter of 2.5-5 mm under a pressure of 20-45 bar. The slurry and resulting product contain 10-28% alkoxylated nonionic surfactant, 40-80% inorganic carrier and 0.5-10% organic washing auxiliary.

Description

Detergents with a comparatively high bulk density of more than 600 g / I have recently attracted increased interest because they require less packaging volume with the same active ingredient content and thus enable savings in packaging raw materials. In principle, washing powders with a high bulk density have been known for a long time. These include e.g. Agents with a high soda or silicate content, such as used to be were obtained simply by mixing the individual components together or by drying aqueous mixtures on trays or heated rolls, extruding or spray crystallization. These specifically heavy powders tend to cake, usually have poor solution properties and cannot be used in modern washing machines with pre-programmed cycle times. These agents have meanwhile been replaced by specifically light powders with a porous grain structure, which are produced by means of hot spray drying and which, as a rule, are rapidly soluble, but on the other hand require a relatively large volume of packaging and transportation.

It is also known that the bulk density of such spray powders can be increased if they are subsequently sprayed with liquid or molten nonionic surfactants. At the same time, this increases the washing power of the detergents because of the favorable washing properties of the nonionic surfactants and avoids the problem of smoke formation in the exhaust air from the spray towers which arises during hot spray drying and is caused by the nonionic material carried along. If you go e.g. However, according to the method in which the nonionic surfactant is applied to spray-dried polyphosphate, only bulk densities of less than 550 g / l are obtained. A similar process is known from US Pat. Nos. 3,838,072, 3,849,327 and 3,886,098, with which a granular porous carrier material is produced by spray drying a slurry of inorganic salts such as sodium silicate, sodium sulfate and sodium triphosphate as well as sulfonate surfactants and soaps then sprayed in a mixer with a nonionic surfactant. In this way, up to 20% by weight of nonionic surfactants can be applied subsequently to the spray-dried carrier material. To improve the pourability, a powder addition of e.g. Talc, finely divided silica or calcined clay is recommended. Also a graying inhibitor in powder form, e.g. Carboxymethyl cellulose, can be mixed in afterwards. The powders thus obtained, loaded with nonionic surfactants, can have a bulk density of more than 500 g / l, for example 700 g / l and a flowability of e.g. have up to 76% of that of dry sand. The size of these powder particles is between 3.3 mm to 0.075 mm, in particular between 0.83 and 0.15 mm.

Granular detergents with a bulk density of at least 500 g / l, which consist of essentially spherical particles of a certain grain size and have a fluidity of 70%, based on dry sand, are known from German Offenlegungsschrift 27 42 683. These agents filled in a plastic bottle have a content of 30 to 80% of builders, 2 to 40% of surfactants, which are essentially non-ionic, 0 to 20% of other additives, 0 to 50% of fillers and 3 to 15% Moisture. It is true that the manufacture of the products described in this way is called arbitrary, for example also by spray drying or granulation. However, the only specifically specified and thus usable way is via a two-stage and therefore complex manufacturing process, in which so-called “base beads” with a porous outer surface and a more or less absorbent inner frame are first produced by spray drying an aqueous slurry, which is then also used the liquid or melted nonionic surfactant is sprayed or soaked. In addition to the complexity of the production process, it is difficult to produce tack-free grains with a content of more than 20% by weight of liquid or low-melting nonionic surfactants. In addition, the products have comparatively unfavorable solution properties in cold tap water, so that undissolved components can remain in the induction boxes or in the tub of drum washing machines.

DE-AS 17 92 434 is finally a process for the production of granular detergents with a content of 2 to 15 wt .-% of anionic and 5 to 20 wt .-% of nonionic surfactants and 25 to 60 wt .-% tripolyphosphate known by spray drying a slurry. The tripolyphosphate used to prepare the slurry must be partially pre-hydrated. This partial prehydration is necessary in order to produce free-flowing powders. The process provides loose powder with a bulk density of less than 550 g / l and - if the proportion of nonionic surfactant significantly exceeds 15% by weight - only very moderate pouring properties. So it turns out to be impossible to transfer the powder in a defined amount from a package or bottle into a measuring cup, because it does not trickle evenly. Rather, the pack inclined to pour out does not evenly flow out even when carefully shaken, but the powder builds up or shoots out of the opening in an uncontrollable manner, which often leads to overflowing of the measuring cup or spilling of large amounts of powder.

• a) ein hohes Schüttgewicht aufweist, so dass das Verpackungsvolumen wesentlich, d.h. ca. auf die Hälfte eines üblichen sprühgetrockneten Mittels erniedrigt werden kann,
• b) einen wesentlich, ca. auf das Doppelte erhöhten Gehalt an waschaktiver Substanz aufweist, so dass der Verbraucher bei trotz geringer, beispielsweise auf die Hälfte erniedrigter Dosierung die gleiche Waschkraft einsetzt wie bei einem herkömmlichen Sprühpulver.
• c) trotz des sich daraus ergebenden hohen Gehaltes an nichtionischen Tensiden, die bekanntlich die Neigung eines Pulvers zum Kleben erhöhen, so gut rieselfähig ist, dass es sich wie eine Flüssigkeit ausschütten und durch einfaches Vor-und Zurückneigen der Vorratspackung exakt in einen Massbecher dosieren lässt,
• d) möglichst in einstufiger Verfahrensweise hergestellt werden kann, ohne dass sich dabei besondere verfahrenstechnische Probleme ergeben.

It was therefore the task of avoiding the known disadvantages to produce a granular detergent component and a detergent therefrom that

• a) has a high bulk density, so that the packaging volume can be reduced significantly, that is to say about half, of a conventional spray-dried agent,
• b) has a substantially, approximately double the content of wash-active substance, so that the consumer uses the same washing power as in the case of a conventional spray powder, despite a low, for example half, reduced dosage.
• c) despite the resulting high content of nonionic surfactants, which is known to increase the tendency of a powder to stick, it is so free-flowing that it can be poured out like a liquid and can be dosed exactly into a measuring cup by simply tilting the supply pack back and forth ,
• d) can be produced in a one-step procedure, if possible, without any particular procedural problems arising.

In this case, the expert was faced with the following problems:

On under normal conditions, i.e. Spray drying process carried out by means of pressure atomization of aqueous slurries appeared to be not very promising for the solution of this task, since this method of operation usually leads to swelling, i.e. porous grains with correspondingly low bulk densities. In the event of subsequent admixing or impregnation with liquefied nonionic surfactants, the pores of the grains could have been filled to a greater or lesser extent and the bulk density could have been increased accordingly, but the two-stage procedure required because of the need to meter, mix or granulate large amounts of powder and then separating the coarser aggregates, a considerable expenditure of equipment and time. Such a procedure also requires the production to be relatively stronger, i.e. grains resistant to abrasion. Such grains, which usually contain higher proportions of sodium silicate as strength enhancers, usually have only moderate solubility properties, especially in cold water, and in many cases have only a limited absorption capacity for liquid or sticky nonionic surfactants.

Methods of directly producing such heavy powder with a high content of nonionic surfactants by spray drying are not known. On the one hand, there were great concerns about the spray drying of powders with a high surfactant content, in particular with a high proportion of nonionic surfactants, because of the risk of dust explosions or because of the expected considerable smoke formation in the exhaust air from the spraying systems. Therefore, the relevant technical and patent literature warns against processing such high-surfactant mixtures in hot spray towers and instead proposes to mix higher proportions of nonionic surfactant with the prefabricated carrier granules by spray granulation. On the other hand, the conventional techniques for preparing and processing the aqueous concentrates (slurries) and the subsequent hot spray drying were developed in such a way that porous, loose powders with a low bulk density were created. These techniques therefore appeared to be unsuitable for producing compact, low-dust powders with a bulk density of about twice as high.

There are essentially two methods for preparing and further processing the slurry. In the case of semi-continuous operation, at least two batch tanks operated in alternating cycles are used. This necessarily results in longer service lives during which there is hydration of the tripolyphosphate and an increase in viscosity. The spraying of such viscous slurries at pressures of 30 to 70 bar by means of nozzles, the bore of which usually has a diameter of 2.5 to 4 mm, results exclusively in loose powders, the bulk density of which is below 0.4 to 0.45 g / ml. Another method known from "Soap & Cosmetical Specialties", August 1972, pages 27-30, 44 and 46 uses continuously operating dosing, mixing and conveying devices. The individual substances are continuously weighed or measured volumetrically, premixed and transferred to a homogenization device. After passing through a filter in which coarse agglomerates are removed or crushed, the slurry reaches the high-pressure pump via a second homogenization device and from there to the spray tower at a pressure of 30 to 70 bar. This continuous working method avoids longer lifetimes and strong viscosity increases of the slurries, but also leads to powders whose bulk density is 0.1 to a maximum of 0.45 g / ml. Low levels of detergent substance, which is synonymous with a high level of builder salts, and high pressures during spraying favor a higher bulk density, but the upper limit, as stated, is 0.4 to 0.45 g / ml. To produce more compact heavy powders, the spray material must therefore be further processed and mixed with specifically heavy powders in devices specially developed for this purpose. This means a higher investment and work effort.

The invention, by means of which the problems outlined are solved, is a process for the production of a granular, free-flowing, water-soluble detergent component consisting of essentially round particles with a bulk density of at least 600 g / l and a grain size of 0.1 up to 2 mm with a content of (a) alkoxylated nonionic surfactants, (b) inorganic carrier substances, (c) other organic washing aids and (d) adsorptively or water bound as hydrate, characterized in that for the preparation of the detergent component containing 10 up to 28% by weight of component (a), 40 to 80% by weight of component (b), 0.5 to 10% by weight of component (c), 8 to 20 wt .-% of component (d) and less than 0.5 wt .-% of anionic surfactants, an aqueous formulation of the ingredients, which has a viscosity of 4000 to 20,000 mPa _' s and a temperature of 85 to 105 ° C, continuously homogenized and sprayed into a drying tower by means of nozzles at a pressure of 20 to 45 bar with a diameter of the nozzle outlet opening of 2.5 to 5 mm, the ratio of pressure at the nozzle inlet to the diameter of the nozzle outlet opening being 4 to 18 bar / mm.

Alkoxylated nonionic surfactants suitable for the preparation of the compositions are ethoxylated alcohols having 12 to 24, preferably 14 to 18 carbon atoms and an average of 3 to 20, preferably 4 to 16, glycol ether groups. The hydrocarbon residues can be saturated or monounsaturated, linear or also methyl-branched in the 2-position (oxo residue) and can be derived, for example, from naturally occurring or hydrogenated fat residues and / or synthetic residues. Ethoxylates derived from cetyl, stearyl and oleyl alcohol and mixtures thereof have proven to be particularly suitable. Examples of these are tallow fatty alcohols with an average of 4 to 8 ethylene oxide groups (EO), tallow fatty alcohol with an average of 10 to 18 EO and oleyl alcohol with an average of 6 to 12 EO as well as their mixtures. Such mixtures of two and more surfactants with different EO content, in which the proportion of higher ethoxylated alcohols predominates, have proven to be particularly advantageous, since the tendency to smoke formation in the exhaust air (so-called pluming) is particularly low and the washing action against mineral ones and fatty soiling is particularly pronounced.

• (a1) Talgalkohol mit 4-6 EO,
• (a2) Talgalkohol mit 12-16 EO,
• (a3) technischer Oleylalkohol (d.h. Gemische aus Oleyl- und Stearylalkohol) mit 6 bis 12 EO,

beispielsweise im Verhältnis (a1):(a2) = 2:1 bis 1:4 bzw. (a1 ):(a2):(a3) wie 2:1:1 bis 2:1:4 bzw. 1:1:1 bis 1:4:1.Examples of this are mixtures of

• (a1) tallow alcohol with 4-6 EO,
• (a2) tallow alcohol with 12-16 EO,
• (a3) technical oleyl alcohol (ie mixtures of oleyl and stearyl alcohol) with 6 to 12 EO,

for example in the ratio (a1) :( a2) = 2: 1 to 1: 4 or (a1) :( a2) :( a3) such as 2: 1: 1 to 2: 1: 4 or 1: 1: 1 to 1: 4: 1.

Alkoxylated alcohols have also proven to be advantageous in the sense of a low tendency to "pluming", in the production of which 1 to 3 mol of propylene oxide and then 4 to 20, preferably 4 to 7, mol of ethylene oxide were added to the alcohol. You can replace components (a1) and (a2) in whole or in part in the aforementioned mixtures.

Ethoxylated alkylphenols with 8 to 12 carbon atoms in the alkyl chain and 4 to 14 EO have also proven to be useful. Mixtures of ethoxylated nonylphenols with (a4) 5 to 7 EO and (a5) 9 to 12 EO in a ratio of 2: 1 to 1: 4 are particularly suitable.

Further suitable nonionic surfactants are those which have a similar distribution of the ethylene glycol or propylene glycol ether groups and are derived from vicinal diols, fatty amines, fatty acid amides and fatty acids. The ethoxylated fatty acid amides also include the fatty acid mono- or diethanolamides or the corresponding fatty acid propanolamides. The water-soluble polyethylene oxide adducts containing 20 to 250 ethylene glycol ether groups and 10 to 100 propylene glycol ether groups on polypropylene glycol, ethylenediaminopolypropylene glycol and alkylpolypropylene glycol with 1 to 10 carbon atoms in the alkyl chain can also be used. The compounds mentioned usually contain 1 to 5 ethylene glycol units per propylene glycol unit.

The detergent component according to the invention contains 10 to 28% by weight, preferably 12 to 25% by weight and in particular 15 to 23% by weight, of ethoxylated nonionic surfactants.

The content of anionic surfactants in the detergent component, i.e. those of the sulfonate or sulfate type, and soap, should be less than 0.5%, preferably 0%. It has been shown that even small amounts of such additives, in particular the smallest additives of soap, cause the grains to swell during spray drying and thus to a decrease in the desired high bulk density and the free-flowing properties.

As inorganic carrier substances there are primarily builders which can also bind or precipitate the hardness constituents of the water. These include the polymer phosphates, especially sodium tripolyphosphate as well as more condensed polymer phosphates, e.g. Sodium tetraphosphate. The polymer phosphates can be mixed with their hydrolysis products, i.e. Orthophosphate and pyrophosphate are present, however, due to the higher washing and calcium binding capacity of the polyphosphates, the lowest possible hydrolysis of the polyphosphate when preparing the slurry and during spray drying should be aimed at by suitable measures. The sodium tripolyphosphate is preferably used in anhydrous form or as a partially hydrated salt with a crystal water content of up to 2% by weight.

Suitable carrier substances are in particular also the synthetic bound water-containing sodium aluminosilicates of the zeolite A type. You can replace the polymer phosphates in whole or in part, i.e. their use also enables the production of phosphate-free agents.

The zeolites are used in the usual hydrated, finely crystalline form, i.e. they have practically no particles larger than 30 11 m and preferably consist of at least 80% of particles smaller than 10 11 m. Your calcium binding capacity, which is determined according to the information in DE 24 12 837, is in the range of 100-200 mg CaO / g. The zeolite NaA can be used in particular, also the zeolite NaX and mixtures of NaA and NaX.

A common constituent of the carrier substance is alkali metal silicates, in particular sodium silicate Likate of the composition Na ₂ 0: Si0 ₂ = 1: 1.5 to 3.5, preferably 1: 2 to 1: 2.5. Mixtures of silicates with different alkali contents can also be used, for example a mixture of Na ₂ O: Si.0 ₂ = 1: 2 and Na ₂ 0: SiO _z = 1: 2.5-3.3, but in the interest of one high bulk density, the proportion of silicates with a higher Na ₂ O content should expediently predominate.

Further useful carrier substances which can be present in a mixture with the compounds mentioned above are sodium carbonate, sodium sulfate and magnesium silicate. Compounds with a high adsorption capacity, such as finely divided silica, clays or bentonites, may also be present.

The proportion of the inorganic carrier substance is a total of 40 to 80% by weight, based on anhydrous or non-hydrated substance, preferably 45 to 70% by weight. The proportion of sodium tripolyphosphate (including the hydrolysis products) is 0 to 60% by weight, preferably 10 to 50% by weight and in particular 20 to 40% by weight. The proportion of the alkali metal silicates is 5 to 20% by weight, preferably 6 to 15% by weight and in particular 6.5 to 12% by weight. The sodium aluminosilicate is present in proportions of 0 to 40% by weight, preferably 3 to 30% by weight and in particular 5 to 25% by weight. The proportion of sodium silicate in such carrier salt mixtures, which essentially consist of sodium tripolyphosphate or zeolite and their mixtures, can also be increased beyond the stated maximum content of 20% by weight, without resulting in major disadvantages for the dissolution behavior of the particles . The same applies in cases in which the proportion of sodium aluminosilicate is increased beyond the stated amount of 40% by weight. In these cases, the proportion of zeolites can be up to 65% by weight.

Although the percentage content of polyphosphate in the detergents can be in the range of conventional heavy-duty detergents, the tendency to reduce phosphate is fully taken into account in the invention. On the one hand, the agents according to the present invention are compared to conventional, i.e. specifically light washing powders are used in a much lower dosage; on the other hand, the proportion of phosphate in favor of the proportion of aluminosilicate can be considerable, i.e. can be reduced to, for example, 10% by weight or even eliminated entirely.

The process product can also contain so-called co-builders as other organic washing aids, which are able to increase the effect of the polyphosphates and sodium aluminosilicates considerably even in small amounts. Polyphosphonic acids or their alkali metal salts are particularly suitable as co-builders. Suitable polyphosphonic acids are 1-hydroxyethane-1,1-diphosphonic acid, aminotri- (methylenephosphonic acid), ethylenediamine tetra- (methylenephosphonic acid) and their higher homologs, e.g. Diethylenetriaminepenta- (methylenephosphonic acid). Other co-builders are complexing aminopolycarboxylic acids. These include in particular alkali salts of nitrilotriacetic acid and ethylenediaminotetraacetic acid. The salts of diethylenetriamineopentaacetic acid and the higher homologues of the aminopolycarboxylic acid mentioned are also suitable. The polyacids mentioned are preferably used as sodium salts.

Also suitable as co-builders are the polymeric carboxylic acids or their salts with a molecular weight of at least 350 in the form of the water-soluble sodium or potassium salts, such as polyacrylic acid, polymethacrylic acid, poly-a-hydroxyacrylic acid, polymaleic acid, polyitaconic acid, polymesaconic acid, polybutene tricarboxylic acid and the copolymers the corresponding monomeric carboxylic acids with one another or with ethylenically unsaturated compounds, such as ethylene, propylene, isobutylene, vinyl methyl ether or furan. The copolymer of maleic acid and acrylic acid in a ratio of 5: 1 to 1: 5 may be mentioned as an example. Small amounts of these co-builders are understood to mean proportions of 0.5 to 10, preferably 1 to 5,% by weight, based on the total amount of the detergent component.

Other organic detergent components that may be present in the spray-dried powder component are graying inhibitors, optical brighteners and additives which regulate the viscosity behavior of the slurries, for example alkali metal salts or toluene, cumene or xylene sulfonic acid and optionally polymers which act as thickeners (for example of the Carbopol type ).

Suitable graying inhibitors are, in particular, carboxymethyl cellulose, methyl cellulose, furthermore water-soluble polyesters and polyamides from polyvalent carboxylic acids and glycols or diamines, which have free carboxyl groups, betain groups or sulfobetaine groups capable of salt formation, and polymers or copolymers of vinyl alcohol, vinyl amide and acrylamide, colloidally soluble in water, acrylamides and acrylamides . These organic washing aid additives can be present in proportions of 0.5 to 10% by weight.

Suitable optical brighteners are the alkali salts of 4,4-bis (-2 "-anilino-4" -morpholino-1,3,5-triazinyl-6 "-amino) -stilbene-2,2-disulfonic acid or similar compounds, which carry a diethanolamino group, a methylamino group or a .beta.-methoxyethylamino group instead of the morpholino group. Brighteners of the substituted diphenylstyrene type, for example the alkali metal salts of 4,4-bis (2-sulfostyryl) diphenyl, 4,4-bis, are also suitable (4-chloro-3-sulfostyryl) diphenyl and 4- (4-chlorostyryl) -4- (2-sulfostyryl) diphenyl.

The agents usually have a water content of 8 to 20 wt .-%, preferably from 12 to 18 wt .-%, including both the adsorb tiv bound water as well as the water of hydration is to be understood.

The proportion of water bound in the hydrated sodium aluminosilicate is about 20% by weight, based on the total amount of the hydrated sodium aluminosilicate; i.e. it is the degree of hydration that is in equilibrium with the environment. This proportion must be taken into account when calculating the amount of water. Basically, the water content should be measured so that there are perfectly free-flowing products. It is preferably 12 to 18% by weight.

The preparation and processing of the aqueous active ingredient concentrate (slurry) intended for spray drying is carried out continuously and with the shortest possible residence times. Suitable devices which are suitable for the continuous processing of slurries are known and are described, for example, in the magazine "Soap, Cosmetics, Chemical Specialties", August 1972, pages 27 to 30, 44 and 46, in particular 28-30, under the name " Dosex slurry system »described in more detail. They consist of automatic weighing and dosing devices for the solid and liquid or pasty raw materials as well as continuously working mixers, pumps and filters for the separation of coarse parts. The inflow of raw materials to the mixing device and the outflow of the homogenized slurry to the high-pressure pump and from there to the spraying device is controlled automatically. This allows short dwell times to be achieved and at the same time counteracts the tendency towards inhomogeneities and segregation phenomena in the slurry.

In a preferred mode of operation, the weighed or metered liquid to pasty raw materials are mixed and homogenized in a mixer, in particular in two or three mixers connected in series.

The liquid constituents, especially the added water, are expediently preheated, i.e. used with a temperature of at least 60 ° C. These include, in particular, the melted nonionic surfactants, the aluminosilicate present as a filter-moist paste and the aqueous solution of sodium silicate (water glass solution). It is also advisable to submit these liquid constituents and, if appropriate, the additional water, and to add the anhydrous constituents, in particular the anhydrous or optionally partially hydrated tripolyphosphate, with vigorous stirring.

In order to ensure sufficient flowability of the slurry and spray products with favorable powder properties, the viscosity of the slurry is adjusted to a range from 4000 to a maximum of 20,000 m ^p as, preferably 5,000 to 15,000 mPa _' s and temperatures from 85 ° C to 105 ° C, for example set to 90 ° C to 102 ° C. The heating is expediently carried out by preheating the liquid raw materials and / or introducing water vapor, in particular superheated water vapor. At the stated temperatures, the hydration of the tripolyphosphate in the slurry is largely prevented or delayed to such an extent that there is no undesirable increase in viscosity within the processing time. This targeted temperature control enables both quick and only moderately hydrating tripolyphosphate qualities to be used. The keeping of liquids and the homogenization of the slurries is supported by the application of strong shear forces with intensive mixing by means of a high-speed stirring device. Turbine stirrers, for example, which run at a number of revolutions of 300 to 600 revolutions per minute are suitable. The use of strong shear forces also prevents the formation of structural viscosities. In the case of such slurry batches which do not contain sodium tripolyphosphate, the use of viscosity-regulating agents additionally ensures that the preferred viscosity ranges are observed.

The aqueous batch normally contains a total of 50 to 35% by weight, preferably 45 to 38% by weight, of water, which also contains the water bound by adsorption or hydrate. Higher water contents are inappropriate because they increase the degree of hydrolysis of the tripolyphosphate, increase energy consumption and lead to a lower bulk density. Lower contents can lead to an excessive increase in the viscosity of the slurry and therefore make special measures such as increasing the mixing and conveying capacity or the addition of viscosity-reducing agents such as toluene, xylene or cumene sulfonate necessary.

After leaving the mixing device, which consists of a single mixer or a cascade of two or more mixers connected in series, the homogenized slurry is pumped to a filter. A dynamic filter is expediently used, by means of which soft agglomerates can be crushed. The slurry then passes through another homogenization device, for example a homogenization pump, and from there it reaches the high-pressure pump, from which it is conveyed to the spray nozzles.

The average dwell time of the slurry after the mixture components have been brought together until the transition to the high-pressure part should be kept as short as possible and not be more than 15 minutes, preferably not more than 10 minutes and in particular not more than 5 minutes.

In a further preferred embodiment, the nonionic surfactants are wholly or partially, in particular 50 to 90%, fed into the delivery line leading to the high-pressure pump and homogeneously distributed in the slurry by means of the homogenization pump mentioned. As a result, the residence time of the nonionic surfactants can be up to 3, in particular less than Shortened 1 minute and an undesirable increase in viscosity can be countered.

Conventional systems can be used to carry out the spray drying process, as are already used for the production of conventional sprayed detergents. Such systems usually consist of towers of round cross-section, which are equipped with ring-shaped spray nozzles in the upper part. They also have supply devices for the dry gases and dedusting systems for the exhaust air. In the generally preferred countercurrent drying, the drying gas is introduced into the lower part of the tower and directed towards the product stream, while in the case of direct current drying, the drying gases are supplied in the top of the drying tower.

The pressure at the nozzle inlet is 20 to 45 bar, preferably 30 to 40 bar, the diameter of the nozzle outlet opening 2.5 to 5 mm, preferably 3.0 to 4.0 mm and the ratio of pressure to diameter of the nozzle outlet opening 4-18 bar / mm and preferably 7.5-13.5 bar / mm. Compliance with these parameters is decisive for the grain properties of the process products. Significantly exceeding these limits in both directions leads to the formation of more or less irregularly formed agglomerates with an undesirable structure, particularly when the pressure is increased or the nozzle is narrowed, resulting in a lower bulk density and poorer pouring properties. Too much lowering of the pressure can lead to poor atomization performance and crusting in the area of the nozzle outlet opening and in the tower. Less favorable powder properties are also achieved with nozzles with too large, i.e. receive a diameter of 5 mm substantially exceeding outlet openings. For example, working with a pressure of approx. 35 bar with a nozzle opening of approx. 3 mm has been proven. It is expedient to use nozzles which have a swirl effect on the material to be sprayed.

The spray drying system is operated with hot air or hot combustion gases, which are preferably conducted in countercurrent to the spray material. The drying gas is expediently introduced tangentially into the tower, which results in a certain swirl effect. The inlet temperature of the dry gas should normally not exceed 250 ° C and should preferably be 180 ° C to 240 ° C, in particular 200 ° C to 240 ° C.

Operation with hotter dry gases requires the use of predominantly highly ethoxylated or mixed alkoxylated surfactants in order to prevent smoke formation in the exhaust air. If the surfactant mixtures of low and highly ethoxylated compounds disclosed as preferred above are used, there are no disturbances due to smoke formation if the temperature range from 200 ° C. to 240 ° C. is maintained.

With regard to the inlet temperature of the dry gas in the spray drying system from 180 ° C. to 240 ° C., preferably from 200 ° C. to 240 ° C., it should be noted that these are temperatures of the gas in the so-called ring channel of the spray tower. The temperature of the dry gas coming into contact with the powder in the lower tower area is usually 10 ° C to 30 ° C lower.

The temperature of the drying gases when leaving the drying tower are generally 80 ° C to 95 ° C. The upper value can be subject to certain fluctuations, which include depends on the outside temperature. It should be selected so that the dew point in the downstream dedusting systems is not exceeded.

The product leaving the spray tower generally has a temperature of 65 ° C to 80 ° C. It has proven to be advantageous if the product is left immediately after leaving the spray tower, i.e. cools within less than 5 minutes, preferably within 2 minutes, to temperatures below 35 ° C., for example to 20 ° C. to 30 ° C. This can be done, for example, in a pneumatic conveyor system that is sufficiently cold, i.e. air at a temperature of less than 30 ° C is operated. Rapid cooling largely prevents diffusion of the nonionic surfactant onto the surface of the sprayed grains. Non-ionic surfactant diffused onto the surface of the particles can reduce their flowability and bulk density. If the temperature of the cooling air is not sufficient to cool the product sufficiently quickly in the hot season, subsequent powdering is recommended.

Finely divided, water-soluble or dispersible solids or fluidizing agents in an amount of 0.01 to 3% by weight, based on the spray product, are suitable for powdering. As a result, the flowability can be further improved or weather-related adverse influences on the powder properties can be avoided. The finely divided synthetic zeolites of the NaA or NaX type have proven particularly useful as coating agents. The positive effect of these zeolites is not only limited to the improved flowability, but also increases the proportion of builders and thus the washing power of the product. Also suitable is finely divided silica with a large specific surface area, in particular pyrogenic silica (Aerosil ^o ), as a fluidizing agent. The proportion of the fluidizing agent is preferably 0.1 to 2% by weight in the case of the zeolite, and preferably 0.05 to 0.5% by weight in the case of the finely divided silica, based on the granular spray product.

Other known powder materials already proposed for powdering sticky detergent granules, such as finely divided sodium tripolyphosphate, sodium sulfate, magnesium silicate, talc, Ben Tonite and organic polymers such as carboxymethyl cellulose and urea resins can also be used if they have a grain size of less than 0.1 mm, for example from 0.001 to 0.08 mm. Coarse-particle powder provenances, as are usually used in detergents and cleaning agents, must first be comminuted accordingly. Coating agents of this type are preferably used in proportions of 1 to 3% by weight.

The spray-dried grains can be coated or powdered before, after or expediently at the same time as the addition of further powder components. These powder components include per-compounds, bleach activators (so-called peracid precursors), enzyme granules, foam inhibitors or foam activators and so-called compounds, i.e. Carrier substances and surfactants, in particular anionic surfactants, or powder products consisting of carrier substances and fabric softeners. An additional mixing process can be saved if the finely divided coating and further powder components are introduced at the same time.

Water-insoluble coating agents such as zeolite and silica aerogels can also be used before spray drying is complete, i.e. by blowing into the lower part of the drying tower on the detergent granules already formed. The coating agent can be introduced into the tower by metering it into the dry air.

The powdering of the spray-dried grains leads, among other things, to a partial smoothing of the grain surface, so that the flow behavior of such grains, which already have very good pourability and flowability, is further improved. The bulk density of the powders can also be increased slightly as a result, since the coating material apparently enables the grains to be packed more densely.

The grain spectrum of the spray products determined by sieve analysis is comparatively narrow, i.e. more than 80 wt .-%, usually even more than 85 wt .-% of the grains are within a range between 0.2 and 0.8 mm mesh size. In the case of a conventional spray powder with a low bulk density, this grain size range generally does not account for more than 50 to 70% by weight. The dust content of the powder component according to the invention and the proportion of oversize particles are correspondingly low, so that subsequent sieving of the tower powder or subsequent addition of dust-binding agents is unnecessary.

The detergent component according to the invention is free-flowing and, in terms of its flowability, exceeds the known, specifically light, sprayed hollow-sphere powder. Their pourability can be compared with that of dry sand, namely the pourability which can be carried out according to a test given in the examples is in the order of more than 60%, preferably from 75 to 95%, of that of dry sand with a specific grain specification .

It is surprising that despite the high content of nonionic surfactants that tend to stick and the lack of fine-pored cavities that are capable of receiving these surfactants, the particles do not tend to stick or release these adhesive components. In contrast to such powders with the same high content of non-ionic surfactant, in which the latter was applied to previously prepared absorbent spray granules, the non-ionic surfactant cannot be partially removed again by pressing between filter paper. The particles according to the invention therefore do not lead to the greasing or "penetration" of conventional, uncoated cardboard packaging.

Another aspect when evaluating a washing powder is the compactibility of the powder. It is inevitable that when a washing powder is automatically filled, it initially takes up a slightly larger bulk volume, which is only slightly reduced even with a brief shaking process. As the packs are transported further to the consumer, compression gradually occurs. The consumer notices this loss of volume when opening the package and often concludes that he has received an incompletely filled package. In the case of conventional, specifically light, hollow spherical powders, this volume loss is 10 to 15%. Granules with predominantly spherical dimensions, e.g. obtained by applying nonionic surfactant to pre-sprayed carrier grains have a volume loss of about 10%. For dry sand, this value is around 8%. The agents according to the invention even exceed these values, i.e. here the volume decreases are usually below 10% and in favorable cases reach a value of 5%. The high volume consistency, combined with the excellent pourability, facilitates in particular precise and reproducible dosing during filling and in use.

In addition, all equipment and procedural aids can be used, which are common in modern spray drying technology.

The process product can be mixed with additional powder products which have been produced by customary methods and have a different powder spectrum. These include, for example, the granular bleaches, the bleach activators, enzymes and foam-influencing agents, which are usually in granular form. However, these powder products also include detergent precursors, so-called compounds, which are composed of anionic sulfonate and / or sulfate surfactants and, if appropriate, soaps together with carriers such as sodium triphosphate, zeolite A and water glass, and by conventional spray drying or mixed granules lation be produced. Textile-softening granules which contain quaternary ammonium compounds as active ingredients together with soluble or insoluble carriers and dispersion inhibitors or which are based on sheet silicates and long-chain tertiary amines are also suitable as additives. These additional powder products are made up of differently designed, known particle shapes, for example more or less spherical beads, prills or granules.

They should be designed or used in such an amount that they do not significantly reduce the bulk density or the pouring properties of the agents. This bulk density is 650 to 850 g / l, preferably 700 to 800 g / l.

Other powder components that can be added to the spray-dried detergents include substances that are unstable under the spray-drying conditions or that lose some or all of their specific effect or that would adversely change the properties of the spray-drying product. Examples of this are enzymes from the class of proteases, lipases and amylases or their mixtures. Enzymes obtained from bacterial strains or fungi, such as Bacillus subtillis, Bacillus licheniformis and Streptomyces griseus, are particularly suitable. Fragrances and foam suppressants, such as silicones or paraffin hydrocarbons, are also generally added to the spray-dried powder component to avoid loss of effectiveness.

Suitable bleaching components for admixing are the perhydrates and per-compounds commonly used in washing and bleaching agents. The perhydrates preferably include sodium perborate, which can be present as a tetrahydrate or as a monohydrate, furthermore the perhydrates of sodium carbonate (sodium percarbonate), sodium pyrophosphate (perpyrophosphate), sodium silicate (persilicate) and urea.

These perhydrates can be used together with bleach activators.

Sodium perborate tetrahydrate in combination with bleach activators is preferred as the bleaching component. The bleach activators include in particular N-acyl compounds. Examples of suitable N-acyl compounds are polyacylated alkylenediamines, such as tetraacetylmethylene diamine, tetraacetylethylenediamine, and acylated glycolurils, such as tetraacetylglycoluril. Further examples are N-alkyl-N-sulfonylcarbonamides, N-acylhydantoins, N-acylated cyclic triazoles, urazoles, diketopiperazines, sulfurylamides, cyanurates and imidazolines. In addition to carboxylic anhydrides, acylated sugars such as glucose pentaacetate are particularly suitable as O-acyl compounds. Preferred bleach activators are tetraacetylethylene diamine and glucose pentaacetate.

The enzymes, foam-influencing agents and bleach activators can be granulated in a known manner and / or coated with water-soluble or water-dispersible coating substances in order to avoid interactions with the other detergent components during storage of the powdery mixtures. Salts which are customary to absorb water of hydration can serve as granulating agents. Suitable coating substances are water-soluble polymers, such as polyethylene glycol, cellulose ethers, cellulose esters, water-soluble starch ethers and starch esters, and nonionic surfactants of the alkoxylated alcohol, alkylphenol, fatty acid and fatty acid amide type.

The detergent component produced according to the invention is only slightly foam-active and can be used in washing machines without problems. In cases where a strong foaming of the detergent is desired during use, especially when washing sensitive fabrics or when washing at low temperatures, which is often carried out by hand, the spray-dried powder product is subsequently expanded with foam-active surfactants and surfactant mixtures, preferably in a compound -Form, added. These include known anionic surfactants of the sulfonate and sulfate type as well as zwitterionic surfactants. Such an addition can also lead to a further increase in washing power. Their addition can be up to 10% by weight, based on the finished mixture, preferably 0.2 to 8% by weight. Suitable anionic surfactants for this are e.g. Alkylbenzenesulfonates, for example n-dodecylbenzenesulfate, olefin sulfonates, alkanesulfonates, primary or secondary alkyl sulfates, sulfofatty acid esters and sulfates of ethoxylated or propoxylated higher molecular weight alcohols, monoalkylated or dialkylated sulfosuccinates, sulfuric acid esters of fatty acid partial ester sulfonates and fatty acid partial ester glycerides and fatty acid partial esters. Suitable zwitterionic surfactants are alkyl betaines and especially alkyl sulfone betaines, e.g. the 3- (N, N-dimethyl-N-alkylammonium) propane-1-sulfonate and 2-hydroxypropane-1-sulfonate.

Of the surfactants mentioned, the alkylbenzenesulfonates, olefin sulfonates, alkanesulfonates, fatty alcohol sulfates, a-sulfofatty acid esters are to be regarded as preferred because of their foam-raising and washing-enhancing action. If emphasis is primarily placed on foam activation, the use of sulfates of ethoxylated fatty alcohols, in particular 1 to 3 glycol ether groups, and alkylsulfobetaines is recommended.

The anionic surfactants or mixtures thereof are preferably in the form of the sodium or potassium salts and as salts of organic bases, such as mono-, di- or triethanolamine. If the anionic and zwitterionic compounds mentioned have an aliphatic hydrocarbon radical, this should preferably be straight-chain and have 8 to 20, in particular 12 to 18, carbon atoms. In the connection Gen with an araliphatic hydrocarbon radical, the preferably unbranched alkyl chains contain an average of 6 to 16, in particular 8 to 14 carbon atoms.

The additional optional anionic and zwitterionic surfactants are also expediently used in granular form. The usual inorganic salts, such as sodium sulfate, sodium carbonate, phosphates and zeolites, and mixtures thereof are used as granulation aids or carrier substances.

Fabric softening additives generally consist of granules containing a softening quaternary ammonium compound (QAV), e.g. Distearyldimethylammonium chloride, a carrier and an additive which delays dispersion in the wash liquor. A typical such granulate is e.g. polydimethylsiloxane activated from 86% by weight of QAV, 10% by weight of pyrogenic silica and 4% by weight of silicone oil (with pyrogenic silica); another granulate has the composition 30% by weight QAV, 20% by weight sodium triphosphate, 20% by weight zeolite NaA, 15% by weight water glass, 2% by weight silicone oil and the rest water.

When selecting the grain specification or when granulating and coating the additives, the aim should be that the bulk density and the average grain size of the particles do not differ significantly from the corresponding parameters of the spray drying products according to the invention, or that the particles do not have a surface that is too rough or too irregular exhibit. However, since the additional powder constituents generally do not exceed a proportion of 10 to 40% by weight, preferably up to 30% by weight (based on the finished mixture), the influence of the additives on the powder properties generally remains small.

example

The device used to prepare the slurries consisted of a cascade of 3 consecutive mixing containers, each with a capacity of 1.5 m ³ . Tanks 1 and 2 were equipped with turbine stirrers (speed 480 rpm). The third tank served as a surge tank for continuous operation. The agitator installed in it rotated at 280 rpm. In order to prevent the slurries from segregating, a maximum fill level of 0.5 m ^{3 was} set in the third container. The average residence time in the 3-stage mixer was less than 5 minutes.

Slurry batches were premixed in the first mixing container every 30 seconds, each batch weighing 123.2 kg. In each case, the liquid constituents heated to a temperature of 70 ° C. were initially introduced. These consisted of melted nonionic surfactants, the aqueous, pumpable aluminosilicate filter cake and a number of aqueous active ingredient solutions. The solids were added at short intervals, the order in which the solids are listed in Table I corresponds. The liquid mixture was heated to 95 ° C. by introducing water vapor (6 bar). The batch was transferred to the second mixing tank via an overflow line, in which the slurry was homogenized while further introducing water vapor. The respective amounts used are listed in Table 1.

• EO = Ethylenoxidgruppen;
• Celluloseether = Gemisch aus 2 Teilen Natriumcarboxymethylcellulose und 1 Teil Methylcellulose;
• EDTMP = Ethylendiaminotetramethylenphosphonat.

It means:

• EO = ethylene oxide groups;
• Cellulose ether = mixture of 2 parts of sodium carboxymethyl cellulose and 1 part of methyl cellulose;
• EDTMP = ethylenediaminotetramethylene phosphonate.

The ratio of sodium silicate and sodium hydroxide solution corresponded to a ratio of Na ₂ 0: SiO _z = 1: 2. The tripolyphosphate was prehydrated (1% water). After complete homogenization, the respective batch contained 96.5 kg of anhydrous solids and 56.7 kg of water (water content 41.0% by weight).

The slurry fed to the 3rd mixing tank and continuously removed from it had a viscosity of 11,500 mPa _' s at 95 ° C. It was passed over a dynamic sieve (Ballestra sieve @) in order to destroy any soft agglomerates that might be present. The slurry was then pumped to a continuously operating homogenizer and, after passing through a high-pressure pump under a pressure of 35 bar, fed to the atomizing nozzles of a spray tower via a riser. The single-substance nozzles designed as swirl nozzles had an opening diameter of 3 mm. The ratio of pressure to nozzle opening was 11.3 bar / mm. The throughput was 12 t / hour, based on spray-dried powder.

The dry gas (throughput of 60,000 m ³ / hour) introduced from below into the spray tower under swirl and heated by burning natural gas had an inlet temperature of 220 ° C measured in the ring channel and an outlet temperature in the filter of 90 ° C. The dust explosion limit was not reached with a powder concentration between 30 and 200 g / m ³ , ie the product is classified in dust explosion class 0. The smoke meter at the outlet of the exhaust air filter shows a deflection between 0.02 and 0.08 divisions.

The spray product was slightly sticky after leaving the spray tower and had a temperature of 70 ° C. It was cooled to a temperature of 26 ° C in less than 1 minute in a pneumatic conveyor. It consisted of non-sticky, free-flowing, essentially round particles with a smooth surface and homogeneous cross-section. The content of coarse fractions (1.6 mm-3 mm) and of dust ^lay below 0.1% by weight. The bulk density of the grains was 750 g / l and the proportion of water which could be removed at 130 ° C. (drying temperature) was 13.1% by weight. A sieve analysis showed the following grain distribution (% by weight):> 1.6 mm = 0%, 1.6-0.8 mm = 3%, 0.8-0.4 mm = 48%, 0.4-0, 2 mm = 48%, 0.2-0.1 mm = 1%, <0.1 mm = 0%.

To determine the flow behavior, 1 liter of the powder was filled in a funnel closed at its outlet opening with the following dimensions.

Dry sea sand with the following grain spectrum was chosen as the reference substance.

The run-off time of the dry sand after opening the outflow opening was set at 100%. The following comparison values were obtained (mean values from 5 experiments):

For the purpose of packaging, 87.0 parts by weight of the test product were mixed with 10 parts by weight of powdered sodium perborate tetrahydrate, which had been sprayed with 0.2 part by weight of perfume oil, 0.5 part by weight of an enzyme granulate, prepared by prilling an enzyme melt, and 2.3 Parts by weight of granulated tetraacetylethylenediamine are mixed, the grain size of the admixed components being in the range between 0.1 and 1 mm. This increases the bulk weight to 760 g / l. The flowability did not change within the error limits.

The mixture proved to be a high-quality detergent that can be used in the temperature range between 30 ° and 100 ° C. With regard to the flushability and the formation of residues in the input devices of fully automatic washing machines, no differences between a loose spray powder and the test product were recognizable. In contrast, the solution properties of the comparison product listed under (d) were poorer, which led to the formation of residues in the induction device and on the textiles.

Example 2

The apparatus described in Example 1, consisting of 3 mixing containers connected in series, was used for the continuous production of the slurry. Via an additional feed provided with a continuously operating metering device, further liquid constituents, in particular liquid or melted nonionic surfactants, could be fed into the line system leading to the high pressure pump between the dynamic sieve and the homogenizer.

A mixture of nonylphenol + 6 EO and nonylphenol + 10 EO in a weight ratio of 1: 2 served as nonionic surfactant component (a). Of this, 33% was introduced into the last mixing tank and 67% into the line system leading to the high pressure pump. The recipe corresponded to that in Table 1 with the modification that the proportion of nonionic surfactant was 12.3 kg and the difference up to 123.2 kg consisted of an aqueous sodium sulfate solution (water content 50% by weight). The average residence time of the total batch was less than 5 minutes, that of the nonionic surfactant less than 1 minute. The viscosity of the mixture was 10,800 mPa.s at the outlet of the third mixing container.

Spray drying was carried out under the conditions given in Example 1 to a water content of 13.5% by weight which can be removed at 130 ° C. The spray product had a bulk weight of 630 g / l. After dusting (powdering) with 2.5% by weight of finely divided, crystalline zeolite NaA, the bulk density increased to 680 g / l. 96.5% by weight of the product had a grain size of 0.2 to 0.8 mm. The proportion of coarse grain (over 1.6 mm) and dust (under 0.1 mm) was less than 0.5% by weight. The pourability based on dry sand was 87%.

Claims (10)

1. A process for the production of a granular, free-flowing detergent component which dissolves rapidly in water and consists of substantially spherical particles having a powder density of at least 600 g/I for a particle size of 0.1 to 2 mm and containing (a) alkoxylated nonionic surfactants, (b) inorganic carriers, (c) other organic washing auxiliaries and (d) water bound by adsorption and water of hydration, characterized in that, to produce the detergent component containing form 10 to 28% by weight of constituent (a), from 40 to 80% by weight of constituent (b), from 0.5 to 10% by weight of constituent (c), from 8 to 20% by weight of constituent (d) and less than 0.5% by weight of anionic surfactants, an aqueous slurry of the ingredients having a viscosity of from 4000 to 20 000 mPa - s and a temperature of from 85 to 105 °C is continuously homogenized and sprayed through nozzles into a drying tower under a pressure of from 20 to 45 bar for a nozzle orifice diameter of from 2.5 to 5 mm, the ratio of the pressure at the nozzle entrance to the nozzle orifice diameter being from 4 to 18 bar/mm.

2. A process as claimed in Claim 1, characterized in that the detergent component contains from 12 to 25% and more especially from 15 to 23% by weight of constituent (a), from 45 to 70% by weight of constituent (b), 0% of anionic surfactants and from 12 to 18% by weight of water bound by adsorption and water of hydration.

3. A process as claimed in Claims 1 and 2, characterized in that the detergent component contains from 45 to 70% by weight of inorganic carriers, of which from 0 to 60% by weight and preferably from 10 to 50% by weight consists of sodium tripolyphosphate, from 5 to 20% by weight and preferably from 6 to 15% by weight of sodium silicate (composition Na₂0:SiO₂ = 1:1.5 to 1:3.5, preferably 1:2 to 1:2,5) and from 0 to 40% by weight and preferably from 3 to 30% by weight of aqueous sodium alumosilicate of the zeolite A type.

4. A process as claimed in Claims 1 to 3, characterized in that the aqueous slurry is adjusted to a viscosity of from 500 to 15 000 m Pa - s at a temperature of from 90 to 102 °C.

5. A process as claimed in Claim 1 to 4, characterized in that the aqueous slurry is adjusted to a water content of from 50 to 35% by weight and preferably from 45 to 38% by weight.

6. A process as claimed in Claims 1 to 5, characterized in that preparation and homogenization of the aqueous slurry are carried out in a cascade of 2 or more successive mixers in which the average residence time of the slurry is no more 10 minutes and, more especially, no more than 5 minutes.

7. A process as claimed in Claims 1 to 6, characterized in that the spraying of the aqueous slurry is carried out at a pressure from 30 to 40 bar with spraying nozzles having an orifice form 3 to 4 mm, the ratio of the pressure at the nozzle entrance to the nozzle orifice diameter being from 7.5 to 13.5 bar/mm.

8. A process as claimed in Claims 1 to 7, characterized in that the entry temperature of the drying gases in the spraying tower is adjusted from 200 to 240 °C and the drying gases flow in countercurrent to the material being sprayed.

9. A process as claimed in Claims 1 to 8, characterized in that the spray dried product is cooled to a temperature below 35 °C within 2 minutes.

10. A process as claimed in claim 1 to 9, characterized in that the product is powdered with finely divided coating orfluidizing agents.