WO1996003488A1 - Process for preparing surfactant granulates - Google Patents

Abstract

The invention concerns low dust content surfactant granulates which have increased bulk density but nevertheless dissolve well in water. These granulates can be prepared by a process in which an anionic surfactant or a plurality of anionic surfactants in its/their acid form and a highly-concentrated aqueous alkaline component are acted upon separately by a gaseous medium, are combined, neutralized in a multi-substance nozzle and, under high propellant pressure, are sprayed in a drying tower. The acid and alkaline components are combined in almost stoechiometric amounts and the resultant solid, finely particulate products are conveyed to a mechanical mixer in which the fine particles are agglomerated to form granulates having a bulk density of at least 400 g/l.

Description

 "Process for the Production of Surfactant Granules"

The invention relates to a process for the production of detergent granules with high bulk density and good dissolving behavior in water, the granulate size being controllable at least in such a way that dust-free or at least low-dust granules are produced.

Surfactant granules can be produced, for example, by conventional drying techniques for surfactant-containing solutions and pastes, especially in the spray tower. For example, European patent application EP-A-0 319819 discloses a process for the preparation of surfactant granules by spray drying, an anionic surfactant in its acid form and a highly concentrated aqueous alkaline component being acted upon separately with a gaseous medium, then combined in stoichiometric amounts, in neutralized with a multi-component nozzle and sprayed at a high propellant pressure in the drying tower. The products obtained are solid or pasty, solid products mostly being relatively dusty, having a relatively high water content and a low bulk density.

Granulation is an alternative to spray drying of surfactant pastes. For example, European patent application EP-A-0430 148 describes a process for producing fatty alcohol sulfate granules which are dispersible in cold water. In this case, a highly concentrated aqueous paste holsulfat fatty alcohols containing less than 14 wt .-% of water and less than 20 wt .-% is further additives, at temperatures between 10 and 45 C ^β so long me¬ mechanically processed until granules are formed . In this way, fatty alcohol sulfate granules are obtained which are already dispersed at washing temperatures between 4 and 30 ° C .; however, the process temperature to be observed and the relatively low maximum water content of the surfactant paste are critical process parameters. In addition, it is not disclosed what bulk weights the granules produced by this process have. From the European patent application EP-A-0402 112 a process for the preparation of fatty alcohol sulfate and / or alkylbenzenesulfonate granules is known, the neutralization of the anionic surfactants in acid form to a paste with a maximum of 12% by weight water with the addition of auxiliaries such as poly ethylene glycols, ethoxylated alcohols or alkylphenols, which have a melting point above 48 ° C, and the granulation is carried out in a high-speed mixer. Again, the amount of water to be maintained represents a critical process parameter. In addition, it is not disclosed what bulk densities the surfactant granules obtained by this process have.

From the European patent application EP-A-0402 111 a process for the production of detergent-active and granular surfactants with a bulk density between 500 and 1200 g / 1 is known, a surfactant preparation containing water as a liquid component and additionally organic polymer and Bu lder substances can contain, mixed with a finely divided solid and granulated in a high-speed mixer. The water content of the surfactant paste also represents a critical process parameter here. If the water content of the surfactant paste is too high, the solid is dispersed so that it can no longer act as a deagglomeration agent. On the other hand, if the solids content exceeds a certain value, the mass will not have the consistency required for granulation.

The object of the invention was to develop a method which does not have the disadvantages of the above-mentioned methods. In particular, low-dust granules with increased bulk density should be produced, which nevertheless have good dissolving behavior in water.

The invention accordingly relates to a process for the preparation of surfactant granules by spray drying, an anionic surfactant or more anionic surfactants in its / its acid form and a highly concentrated aqueous alkaline component being separately charged with a gaseous medium, combined, neutralized in a multi-component nozzle and at a high rate Propellant gas pressure are sprayed in the drying tower, the combination of the acidic and alkaline components in almost stoichiometric amounts and the solid, one-piece products obtained in a mechanisc working mixer are transferred in which the fine particles are agglomerated into granules having a bulk density of at least 400 g / l.

The first process step, spray neutralization, can be carried out, for example, according to the teaching of European patent application EP-A-0319819. At this point, reference is expressly made to the disclosure in European patent application EP-A-0319819.

A preferred embodiment of the present invention provides that the acidic and alkaline reactant streams separately charged with a gaseous medium are brought together via a single multi-component nozzle, for example via a 2-component nozzle or a 3-component nozzle, and dry ¬ nungsraum be sprayed. It is also possible to bring the gas-charged reactant streams together before the nozzle. It should be noted, however, that the distance between the location of the junction from the spraying device depends on the process conditions and the material systems used, but is preferably kept as small as possible in order to avoid clogging of the nozzle due to premature neutralization reactions. Therefore, the first-mentioned variant of combining the reactant streams in the nozzle is to be preferred, since in this case the neutralization takes place essentially in the nozzle or directly when it emerges from the nozzle. Of course, it is also possible for the combined acidic and alkaline reactant streams to be sprayed into the drying chamber via a plurality of multi-component nozzles. This is particularly preferred when products are to be produced from different types of anionic surfactants and thus different, combined acidic and alkaline reactant streams are to be sprayed.

In the practical implementation of the method of the invention, the starting materials are introduced, for example using piston pumps, in almost stoichiometric metered amounts into one or two non-modified commercial nozzle (s) or one or two spray tube (s). The gaseous medium (propellant) is mixed in directly in front of the nozzle. This means that the gaseous medium is mixed into the reactant streams before they meet in front of or in the nozzle. Further technical details on the implementation of the method, for example with regard to the Control of the reaction temperatures, the flow rate of the reactant streams or the pressure at which the reaction mixture is sprayed into the drying room can be found in European patent application EP-A-0319819. In the context of this invention, “almost stoichiometric amounts” mean that the ratio of the number of acidic groups to alkaline groups is preferably in the range from 1.1: 1 to 0.8: 1 and in particular from 1: 1 to 0.9 : 1 lies.

The anionic surfactants in their acid form can be carboxylic acids, sulfuric acid semesters and sulfonic acids, preferably fatty acids, alkylarylsulfonic acids, α-sulfofatty acid esters and the sulfuric acid semiesters of optionally alkoxylated, especially ethoxylated alcohols and fatty alcohols and / or sulfosuccinic acid. In the broadest sense, fatty acid esters, in particular fatty acid methyl esters, can also be used, in which case the ester group is not saponified, but instead is saponified.

Suitable anionic surfactants in their acid form are therefore in particular either an anionic surfactant in its acid form or a mixture of the group of anionic surfactants in their acid form, optionally in combination with nonionic, amphoteric and / or cationic surfactants. Preferred anionic surfactants in their acid form are Cβ-C ^ alkylsulfonic acids, Cg-Ci3-alkylbenzenesulfonic acid, usually called dodecylbenzenesulfonic acid, and α-sulfofatty acid methyl ester in its acid form. Particularly preferred alkylsulfonic acids are the sulfuric acid monoesters from primary alcohols of natural and synthetic origin, in particular from fatty alcohols, e.g. B. Ko¬ fatty alcohols, tallow alcohols, oleyl alcohols, lauryl, myristyl, palmityl or stearyl alcohol, or the Cιo-C2θ-oxo alcohols, and those secondary alcohols of this chain length. The sulfuric acid monoesters of the alcohols ethoxylated with 1 to 6 mol of ethylene oxide, such as 2-methyl-branched Cg-Cu alcohols with an average of 3.5 mol of ethylene oxide, are also suitable. In particular, esters of α-sulfofatty acids (ester sulfonic acids) which, by sulfonation of the methyl esters of fatty acids of vegetable and / or animal origin with 10 to 20 C atoms in the fatty acid molecule, for example the α-sulfonated methyl esters of the hydrogenated coconut oil, , Palm kernel or tallow fatty acids, as well as those caused by the ester cleavage available α-sulfo fatty acids (diacids) used. The use of mixtures of monoacids and diacids with other anionic surfactants in their acid form, for example with alkylbenzenesulfonic acids and / or fatty alkylsulfonic acids, is also preferred.

Also suitable are alkanesulfonic acids, which are obtainable from Ci2-Ci8-alkanes by sulfochlorination or sulfoxidation.

Even in the spray neutralization step, further ingredients can be used, which are preferably derived from the group of ingredients that are usually used in spray-dried washing or cleaning agents. In particular, nonionic surfactants, but also builder substances such as phosphates and zeolites or polycarboxylic acids or their salts and polymeric polycarboxylates, and also inorganic salts such as carbonates, bicarbonates, silicates, sulfates and bisulfates are suitable. Solid substances can be blown into the spray drying room, for example, while liquid components can additionally be introduced into the spray drying room in combination with one of the reactant streams. Another possibility is also to introduce additional anionic surfactant and / or nonionic, surfactant pastes into the spray drying room in addition to the reactant streams. In a preferred embodiment of the invention, therefore, an anionic surfactant in its acid form or a mixture of anionic surfactants in its acidic form is used in combination with anionic, nonionic, amphoteric and / or cationic surfactants.

Suitable anionic surfactants, which can be introduced into the process in paste form in particular, are all salts which are concordant with the acid forms mentioned above.

Nonionic surfactants preferably used in combination with these anionic surfactants in acid form are derived from liquid alkoxylated, advantageously ethoxylated, in particular primary alcohols with preferably 9 to 18 carbon atoms and an average of 1 to 40 moles of ethylene oxide per mole of alcohol, in which the alcohol residue may be linear or methyl-branched in the 2-position, or may contain linear and methyl-branched residues in the mixture, as is usually present in oxo alcohol residues. In particular are however, linear residues from alcohols of native origin with 12 to 18 carbon atoms are preferred, such as from coconut, tallow or oleyl alcohol. The degrees of ethoxylation given represent statistical mean values, which can be an integer or a fractional number for a special product. Alcohol ethoxylates with a narrow homolog distribution (narrow range ethoxylates, nre) are also suitable. In particular, alcohol ethoxylates are preferred which have an average of 2 to 8 ethylene oxide groups. The preferred ethoxylated alcohols include, for example, Cg-Cn-oxo alcohol with 7 EO, Ci3 ~ Ci5-0xoalcohol with 3 EO, 5 EO or 7 EO and in particular Ci2-C _j 4-alcohol with 3 EO or 4 EO, Ci2- Ci8 alcohols with 3 EO, 5 EO or 7 EO and mixtures thereof, such as mixtures of Ci2-Ci4 alcohol with 3 EO and Cχ2-Ci8 alcohol with 5 EO. In addition, alcohols are preferred which have more than 10 EO per molecule of alcohol, for example 11 EO, 14 EO, 20 EO, 25 EO, 30 EO or also 40 E0 such as tallow fatty alcohol with 40 E0. Furthermore, nonionic surfactants which can be used are alkylglycosides of the general formula R- 0- (G) _x , in which R is a primary straight-chain or aliphatic radical which is methyl-branched in the 2-position and has 8 to 22, preferably 12 to 18, atoms, G is a symbol , which stands for a glycose unit with 5 or 6 carbon atoms, and the degree of oligo erization x is between 1 and 10, preferably between 1 and 2 and in particular is significantly less than 1.4.

The neutralization or saponification reaction is preferably carried out with concentrated aqueous alkaline solutions, for example solutions of hydroxides, carbonates or hypochlorites of sodium or potassium, in particular with a concentrated aqueous sodium hydroxide solution and / or potassium hydroxide solution, concentrations around 45 to 55% by weight are particularly preferred. A further dilution of the reactant streams with water is not necessary.

Suitable gaseous medium (propellant gas) are, in particular, gases such as air or nitrogen which are inert to the starting and end materials. In principle, water vapor is also suitable here, in particular if one of the reactant streams or the reactant streams is to be heated before the merging.

Within the scope of this invention, only solid products are to be produced in this first process stage. These are relatively dusty, and show relatively poor flow properties and in particular a high time consolidation and thus a low storage stability and have a relatively high water content of, for example, above 5 to 15% by weight and a low bulk density of, for example, 200 to 350 g / l.

These solid products can now be transferred to any of the known mechanically operating mixers or granulators, with the aid of which the powders are granulated and at the same time recompacted to bulk densities of at least 400 g / 1, preferably of about 420 to 650 g / 1 can. Such mixers are, for example, ploughshare mixers or annular layer mixers, such as those sold by the companies Lödige, Imcatec or Drais, but also mixer types from Schugi (Flexomiχ (R)) or Niro (ZigZag mixer ( ^R ) or HEC granulator ( ^R )). Both batch and continuous mixer types can be used, with the continuously operating mixer types being preferred.

If the chemical composition and the water content of the end product are specified, this granulation is carried out at a temperature at which the solid product softens and can thus be shaped. In the lower temperature range, granules with an only slightly increased bulk density are formed; however, this increases at higher temperatures. If the temperatures are too high, however, the mixture to be granulated is softened to a great extent and the mixer becomes blocked by pasty caking on walls and tools. With a given chemical composition, the preferred temperature range also shifts downward with increasing water content.

Depending on the optimal granulation conditions, drying or moistening, cooling or heating the spray-neutralized product before or during the granulation can be advantageous.

In a preferred embodiment of the invention, the spray-neutralized powders are subjected to a treatment in a fluidized bed before the granulation, and the powders can be dried and / or cooled. Advantageously, cooling or initially drying and then cooling of the products is carried out, preferably such Product temperatures are set which have proven to be advantageous in the granulation, so that direct further processing of the product is made possible.

In a further preferred embodiment of the invention, the powdery products produced in the spray chamber are even further processed directly, that is to say without intermediate storage and without treatment in the fluidized bed, in the mechanically working mixer.

It has proven to be particularly advantageous if the granulation in the mixer is carried out at product temperatures between 30 and 80 ° C., preferably between 40 and 70 ° C. Although it is possible to incorporate solid and / or liquid additional components in this process stage, it is not necessary. It was particularly surprising that the granulation of the dusty products succeeded without the addition of liquid components, which usually had to be added as a granulating liquid. On the contrary, without the addition of liquid components, advantageous low-dust granules with controllable particle size and high bulk density are obtained, which also show very good flow behavior, so that granulation of the spray-dried powder without the addition of liquid components is a preferred embodiment.

Without wishing to be bound by this theory, the applicant assumes that the relatively high water content of the sprayed and dusty products from the first process stage serves as a "liquid reserve", which enables granulation. It is precisely the parameter that leads to the manifold disadvantages of the powdery products in the first process stage that results in particularly advantageous products after the second process stage.

If desired, further additives can of course be added at this point, as is customary in conventional granulation, even at these temperatures liquid to pasty additives such as nonionic surfactants (see above), but also anionic surfactant pastes (see above). In order to prevent the time hardening of the granular end products from deteriorating, it is advantageous in many cases, in particular if liquid components are added during the granulation and the proportion of the added liquid components exceeds 5% by weight, to further solids Add usual ingredients of washing or cleaning agents. The builder substances and inorganic salts mentioned above come primarily into consideration here. However, particularly preferred additives are also peroxy bleaching agents, such as perborate and percarbonate, but also conventional graying inhibitors and substances which prevent the fabric from being soiled again. Enzymes can also be granulated at this stage; however, it is preferred to add these to the end product in granular form. At this point, water and aqueous solutions are less preferred: on the one hand, the water - as stated above - is not required as a granulating liquid and, on the other hand, a subsequent drying would have to be connected in most cases, but this is not preferred. Such drying of the granules and thus a concentration of the granules following the second process stage can, in principle, be carried out, for example, in a so-called long-term dryer, for example in a fluidized bed or a vacuum dryer. Just like drying, cooling the granules, as is known from the prior art, is also possible. Furthermore, customary processing steps such as sieving and, if appropriate, recycling fine and coarse-grained fractions into the mixer can follow.

In particular finely divided solids, for example zeolites, in particular zeolite A and / or zeolite P, silicates, silicas, sulfates, calcium stearates and mixtures thereof, are advantageously added at the end of the granulation step in order to improve the storage stability of the granules.

In a preferred embodiment of the invention, soaps, alkyl sulfates and / or fatty acid isethionates are also added as solid additional components in the granulation stage. It has been shown that the dissolution behavior of the granular end products produced according to the invention in water, which in themselves have good values, by adding these solids, for example in amounts of 0.5 to 15% by weight, preferably in amounts of 1 to 10 wt .-%, can still be increased. The products obtained according to the invention, which are quickly soluble in water, are low-dust granules. The grain sizes or certain grain size ranges can be controlled via the process parameters of the mechanically operating mixers or granulators used. Bulk weights between 400 and 600 g / l and particle size ranges are preferably set, less than 5% by weight having a particle diameter below 0.1 mm and at least 85% by weight having a maximum particle diameter of 1.6 mm.

In a particularly preferred embodiment of the invention, surfactant granules having the following composition are produced which contain more than 40% by weight, preferably 50 to 95% by weight and in particular 80 to 90% by weight, of anionic surfactants, preferably C8-C22- Have alkyl sulfates, in particular C12-Ciβ-alkyl sulfates, Cjs-Cis-alkyl sulfates or cuts with higher proportions of C12 ^and d j4.

B e i s p i e l e

In Examples 1 to 6, analogously to the disclosure of EP-A-0 319 819, half-sulfuric acid (FAS1 and FAS2) were spray-neutralized with 50% by weight sodium hydroxide solution via a multi-component nozzle. The spray-neutralized products FAS1 and FAS2 obtained had the composition given below (Table 1). In Examples 2 to 6, the spray-neutralized, relatively dusty products were transferred directly, ie without intermediate storage, to the mixers specified below. In all examples 2 to 6, granules with a bulk density of at least 400 g / l were produced which had good dissolving behavior in water.

Table 1: Composition of the spray-neutral products:

Examples 1, 2, 3 Examples 4, 5, 6

Remaining fatty alkyl sulfates FAS 1 Remaining fatty alkyl sulfates FAS 2

(C chain cut: (C chain cut:

2 wt% C12, C1 24 wt% C12, C14

29% by weight Ci6 23% by weight Ci6

69% by weight Ciβ) 54% by weight Ciβ)

2.0% by weight sodium sulfate 2.0% by weight sodium sulfate

1.5% by weight sodium hydroxide 1.5% by weight sodium hydroxide

5.0% by weight of unsulfated fatty alcohol 4.0% by weight of unsulfated fatty alcohol

Water like in water like in

Table 2 indicated Table 2 indicated

Table 2: Properties of products 2 to 6 compared to 1

Examples

1 2 3 4 5 6 sprühneutra¬ granular end product lized ex ploughshare mixer ex Ring¬

Powder layer mixer

FAS type FAS1 FAS1 FAS1 FAS2 FAS2 FAS2

Schüttge¬ 310 480 520 402 475 405 weight in

9/1

Grain size distribution: to 1.6 mm 4.2 9.2 4.3 7.3 0.5

0.8 mm 8.1 13.7 8.5 9.3 8.9

0.4 mm 29.1 33.7 33.1 30.2 33.4

0.2 mm 8 37.6 32.8 35.9 36.8 33.6

0.1 mm 41.3 18.5 10.0 16.2 14.0 22.7 of which 50.7 2.5 0.6 2.0 2.4 0.9

Granulation parameter:

Kpnti K K K

Baten B B mean 1 2 1.5 1.5 <0.5

Dwell time in

Minutes

Tempera¬ 60 60 35 46 32 tur in ° C

Wasserge¬ 6 5 5 4.5 4.5 5.5 stop in

% By weight

Outlet 3.1 0.4 diameter in m *

Spout diameter of radially symmetrical stainless steel bunkers after 24-hour storage according to the Jenike shear test (AW Jenike, Gravity Flow of Bulk Solids, Bulletin of the University of Utah No. 108, Vol. 52 (No.29), October 1961 and AW Jenike, Storage and Flow of Solids, Bulletin of the University of Utah No. 123, Vol. 53 (No.26), November 1964) Example 1 was repeated with the FAS 2 type. The composition, bulk density and grain size distribution were in the same size range as for FAS 1.

Examples 2 and 3 (Table 2) show the effects of the residence time on the particle size distribution and the bulk density.

Examples 4 and 5 show the effects of the granulation temperature on the bulk density.

The improved flow properties of the products 2 to 6 produced according to the invention can be read off from the value of the required outlet diameter of a bunker: for a further processing of a relatively dusty, only spray-neutralized product according to Example 1 after storage in a bunker, this would have to have an outlet diameter of 3 , 1 m, while for products according to one of the examples 2 to 6 outlet diameters of less than 1 m are sufficient.

Claims

Patent claims 1. Process for the production of surfactant granules by spray drying, in which one anionic surfactant or more anionic surfactants in its / their Säu¬ reform and a highly concentrated aqueous alkaline component ge separately acted upon with a gaseous medium, combined, neutralized in a multi-component nozzle and at a high propellant pressure in the Drying tower are sprayed, characterized in that the combination of the acidic and alkaline components takes place in almost stoichiometric amounts and the solid, finely divided products obtained are transferred to a mechanical mixer in which the fine particles are granulated with a Bulk weight of at least 400 g / 1 agglomerated. 2. The method according to claim 1, characterized in that the spray-neutralized powder is subjected to a treatment in a fluidized bed before granulation, the powders being able to be dried and / or cooled, preferably cooled or first dried and then cooled. 3. The method according to claim 1 or 2, characterized in that the powdery products produced in the spraying room are further processed without intermediate storage in the mechanically operating mixer. 4. The method according to any one of claims 1 to 3, characterized in that the granulation in the mixer is carried out at product temperatures between 30 and 80 ° C, preferably between 40 and 70 ° C. 5. The method according to any one of claims 1 to 4, characterized in that the granulation of the spray-dried powder takes place without the addition of liquid components. 6. The method according to any one of claims 1 to 5, characterized in that the granulation of the spray-dried powder is carried out with solid additive components. 7. The method according to claim 6, characterized in that soaps, alkyl sulfates and / or fatty acid isethionates are used as solid additive components in the granulation stage. 8. The method according to any one of claims 1 to 7, characterized in that as anionic surfactants in their acid form fatty acids, alkylarylsulfonic acids such as Cg-C ^ alkylbenzenesulfonic acid, α-sulfofatty acid esters and the sulfuric acid semiesters of optionally alkoxylated, especially ethoxylated alcohols and fatty alcohols and / or the sulfosuccinic acid can be used. 9. The method according to any one of claims 1 to 8, characterized in that an anionic surfactant is used in its acid form or a mixture of the group of anionic surfactants in their acid form in combination with anionic, nonionic, amphoteric and / or cationic surfactants. 10. The method according to any one of claims 1 to 9, characterized in that in the spray neutralization, the ratio of the number of acidic groups to the alkaline groups in the range from 1.1: 1 to 0.8: 1, preferably from 1: 1 to 0.9: 1 lies. 11. The method according to any one of claims 1 to 10, characterized in that bulk densities of 400 to 600 g / 1 and grain size ranges are set, less than 5% by weight having a particle diameter below 0.1 mm and at least 85% by weight. -% have a maximum particle diameter of 1.6 mm. 12. The method according to any one of claims 1 to 11, characterized in that surfactant granules, which more than 40 wt .-%, preferably 50 to 95 wt .-% and in particular 80 to 90 wt .-% anionic surfactants, preferably C8 -C22-alkyl sulfates, in particular Ci2-Ci8-alkyl sulfates, Cis-Ciβ-alkyl sulfates or cuts with higher proportions of C12 and C14 can be produced.