EP1007613A1

EP1007613A1 - Method for producing water- and dust-free anion tenside granules

Info

Publication number: EP1007613A1
Application number: EP98943891A
Authority: EP
Inventors: Hans-Christian Raths; Werner Seipel; Bernd Fabry; Hermann Hensen
Original assignee: Cognis Deutschland GmbH and Co KG
Current assignee: BASF Personal Care and Nutrition GmbH
Priority date: 1997-08-25
Filing date: 1998-08-17
Publication date: 2000-06-14
Also published as: WO1999010459A1

Abstract

The invention relates to a method for producing water- and dust-free anion tenside granules with a high bulk density. According to said method, aqueous pastes of fatty acid polyglycol ester sulphates with a solids content of at least 20 weight per cent are dried to a residual water content of less than 2 weight per cent in a horizontally positioned film evaporator with rotating internals. At the same time, the pastes are made to form lumps. This is achieved by means of a decreasing temperature gradient applied to the film evaporator from product entry to product exit, and by gassing the pastes with air in the counter-current. The pastes are also dried exclusively by the heated walls. The inventive granules are particularly suitable for producing hard soap.

Description

Process for the preparation of water and dust-free anionic surfactant granules

Field of the Invention

The invention relates to a process for the simultaneous drying and granulation of aqueous fatty acid polyglycol ester sulfate pastes using a thin film evaporator.

State of the art

Fatty acid polyglycol ester sulfates are characterized by excellent detergent properties and high ecotoxicological compatibility. For this reason, these anionic surfactants are becoming increasingly important. In addition to use in liquid formulations, such as dishwashing detergents or hair shampoos, there is now also a market need for solid, water-free forms of supply which can also be incorporated, for example, in powder detergents, toothpastes or syndet soaps.

On an industrial scale, liquid surfactant preparations are generally dried by conventional spray drying, in which the aqueous surfactant paste is sprayed at the top of a tower in the form of fine droplets, to which hot drying gases are directed. However, the drastic conditions often lead to hydrolysis, undesirable discoloration of the products, caking on the walls of the spray towers and, as a result, contamination of the dry material by charred residues. The repeated cleaning of the towers also leads to downtimes, which can make the process costly. A further problem is that prior art methods do not lead to the particularly preferred heavy powders with a bulk density above 500 g / l with a simultaneously greatly reduced dust content. However, these two parameters are of particular importance for economic, application-related and safety-related reasons.

From the German published patent application DE-A1 4209339 (Henkel) a process for the production of free-flowing detergent and cleaning agent granules is known, in which the dewatering in turbine dry, ie in cylindrical drying apparatus in a horizontal design with rotating internals. Anionic surfactants with sulfate-containing detergent pastes can also be dried.

Accordingly, the complex object of the present invention was to convert aqueous fatty acid polyglycol ester sulfate pastes into practically water- and dust-free granules with as little technical effort as possible without the use of inorganic or organic carriers, which at the same time had an acceptable color quality, a high bulk density, and good Flowability, satisfactory storage stability and, in comparison to the products of the prior art, are characterized by at least comparable application properties.

Description of the invention

The invention relates to a process for the preparation of water- and dust-free anionic side granules with a high bulk density, in which aqueous pastes of fatty acid polyglycol ester sulfates with a solids content of at least 20 and preferably in the range from 25 to 75% by weight in a horizontal Arranged thin-film evaporator with rotating internals dries down to a residual water content of less than 2, preferably less than 1, 5 and in particular less than 1% by weight and brings it into pieces, whereby a negative temperature gradient is applied to the thin-film evaporator from the product inlet to the product discharge, im Counter-current gassed with air and drying takes place exclusively via the heated wall.

Surprisingly, it was found that a horizontally arranged thin-film evaporator is ideally suitable for converting aqueous fatty acid polyglycol ester sulfate pastes into dry, light-colored, free-flowing and non-sticky granules without product discoloration and caking on the walls. The products have a high bulk density in the range of 550 to 650 g / l and an average grain diameter of 2.0 to 2.8 mm, which leads to a reduction in unwanted water absorption and caking of the particles. This also ensures high storage stability. At the same time, they are dust-free, ie the proportion of particles with a diameter below 200 μm is below 5% by weight. This finding is all the more surprising since components of the type mentioned are known in principle for drying valuable materials, but the resulting powders do not meet the requirements mentioned with regard to the bulk density or the dust and residual water content. In a particular embodiment of the invention, mixtures of fatty acid polyglycol ester sulfates with alkyl and / or alkenyl oligoglycosides, fatty acid N-alkyl polyhydroxyalkylamides, monoglyceride (ether) sulfates or betaines are used. Fatty acid polyglycol ester sulfates

Fatty acid polyglycol ester sulfates, which preferably follow the formula (I),

in which R ¹ CO is a linear or branched, saturated or unsaturated acyl radical having 6 to 22 carbon atoms, x is an average of 1 to 3 and AO is a CH2CH2O-, CH ₂ CH (CH ₃ ) 0- and / or CH ( CH ₃ ) CH ₂ 0 radical and X represents an alkali and / or alkaline earth metal, ammonium, alkylammonium, alkanolammonium or glucammonium, are known anionic surfactants and are prepared by sulfation of the corresponding fatty acid polyglycol ester. These in turn can be obtained using the relevant preparative processes in organic chemistry. For this purpose, ethylene oxide, propylene oxide or a mixture thereof - in random or block distribution - is added to the corresponding fatty acids, this reaction being acid-catalyzed, but preferably in the presence of bases, such as, for example, sodium methylate or calcined hydrotalcite. If a degree of alkoxylation of 1 is desired, the intermediates can also be prepared by esterifying the fatty acids with an appropriate alkylene glycol. The sulfation of the fatty acid polyglycol esters can be carried out in a manner known per se with chlorosulfonic acid or preferably gaseous sulfur trioxide, the molar ratio between fatty acid polyglycol ester and sulfating agent being in the range from 1: 0.95 to 1: 1, 2, preferably 1: 1 to 1: 1 , 1 and the reaction temperature can be 30 to 80 and preferably 50 to 60 ° C. It is also possible to undersulfate the fatty acid polyglycol esters, ie to use significantly fewer sulfating agents than would be stoichiometrically required for complete conversion. For example, if molar amounts of fatty acid polyglycol ester to sulfating agent of 1: 0.5 to 1: 0.95 are selected, mixtures of fatty acid polyglycol ester sulfates and fatty acid polyglycol esters are obtained, which are also advantageous for a whole range of applications. In order to avoid hydrolysis, it is very important to carry out the neutralization at a pH in the range from 5 to 9, preferably 7 to 8. Typical examples of suitable starting materials are the addition products of 1 to 3 moles of ethylene oxide and / or propylene oxide, but preferably the adducts with 1 mole of ethylene oxide or 1 mole of propylene oxide with caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, Palmoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, elaeostearic acid, arachidic acid, gadoleic acid, behenic acid and erucic acid and their technical mixtures, which are then sulfated and neutralized as described above. Fatty acid polyglycol ester sulfates of the formula (I) are preferably used in which R ¹ CO stands for an acyl radical having 12 to 18 carbon atoms, x for an average of 1 or 2, AO for a CHaCH∑O group and X for sodium or ammonium, such as, for example, lauric acid + 1EO sulfate sodium salt, lauric acid + 1 EO sulfate ammonium salt, coconut fatty acid + 1 EO sulfate sodium salt, coconut fatty acid + 1 EO sulfate ammonium salt, tallow fatty acid + 1EO sulfate sodium salt, tallow fatty acid + 1EO sulfate ammonium salt and mixtures thereof.

Alkyl and / or alkenyl olefin glycosides

Alkyl and alkenyl oligoglycosides, which can be dried as optional surfactants, are known nonionic surfactants which follow the formula (II),

R ² 0- [G] _p (II)

in which R represents an alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G represents a sugar radical having 5 or 6 carbon atoms and p represents numbers from 1 to 10. They can be obtained according to the relevant procedures in preparative organic chemistry. As representative of the extensive literature, reference is made here to the documents EP-A1 0301298 and WO 90/03977. The alkyl and / or alkenyl oligoglycosides can be derived from aldoses or ketoses with 5 or 6 carbon atoms, preferably glucose. The preferred alkyl and / or alkenyl oligoglycosides are thus alkyl and / or alkenyl oligoglucos.de. The index number p in the general formula (II) indicates the degree of oligomerization (DP), ie the distribution of mono- and oligoglycosides, and stands for a number between 1 and 10. While p in a given compound must always be an integer, and especially here can assume the values p = 1 to 6, the value p for a certain alkyl oligoglycoside is an analytically determined arithmetic parameter, which usually represents a fractional number. Alkyl and / or alkenyl oligoglycosides with an average degree of oligomerization p of 1.1 to 3.0 are preferably used. From an application point of view, those alkyl and / or alkenyl oligoglycosides are preferred whose degree of oligomerization is less than 1.7 and is in particular between 1.2 and 1.4. The alkyl or alkenyl radical R ² can be derived from primary alcohols having 4 to 11, preferably 8 to 10, carbon atoms. Typical examples are butanol, capro alcohol, caprylic alcohol, capric alcohol and undecyl alcohol and their technical mixtures, such as are obtained, for example, in the hydrogenation of technical fatty acid methyl esters or in the course of the hydrogenation of aldehydes from Roelen's oxosynthesis. Alkyl oligoglucosides of chain length Cβ-Cio (DP = 1 to 3) are preferred, which are obtained as a preliminary step in the separation of technical C _δ- Ciβ-coconut fatty alcohol by distillation and contaminated with a proportion of less than 6% by weight of Ci2-alcohol can be as well as alkyl oligoglucosides based on technical Cθ / n-oxo alcohols (DP = 1 to 3). The alkyl or alkenyl radical R ² can also be derived from primary alcohols having 12 to 22, preferably 12 to 14, carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol, cetyl alcohol, palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol, brassidyl alcohol and their technical mixtures, as described above, which can be obtained as described above. Alkyl oligoglucosides based on hardened Ci2 / are preferred. -Coconut alcohol with a DP of 1 to 3. Fatty acid N-alkyl polyhydroxyalkvamide

Fatty acid N-alkylpolyhydroxyalkylamides, which can also be mini-dried as optional surfactants, are nonionic surfactants which follow the formula (III)

Rt

in the R ³ CO for an aliphatic acyl radical with 6 to 22 carbon atoms, R ⁴ for an alkyl or hydroxyalkyl radical with 1 to 4 carbon atoms and [Z] for a linear or branched polyhydroxyalkyl radical with 3 to 12 carbon atoms and 3 to 10 hydroxyl groups stands. The fatty acid N-alkylpolyhydroxyalkylamides are known substances which are usually obtained by reductive amination of a reducing sugar with ammonia, an alkylamine or an alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride can. With regard to the processes for their production, reference is made to US Pat. Nos. 1,985,424, 2,016,962 and 2,703,798 and international patent application WO 92/06984. An overview of this topic by H.Kelkenberg can be found in Tens.Surf.Deterg. 25, 8 (1988). The fatty acid N-alkylpolyhydroxyalkylamides are preferably derived from reducing sugars having 5 or 6 carbon atoms, in particular from glucose. The preferred fatty acid N-alkyl polyhydroxyalkylamides are therefore fatty acid N-alkylglucamides, as represented by the formula (IV):

R ⁴ OH OH OH

I I I I

R3CO-N-CH ₂ .CH-CH-CH-CH-CH ₂ OH (IV)

I OH

The fatty acid N-alkylpolyhydroxyalkylamides used are preferably glucamides of the formula (IV) in which R ^{4 is} methyl and R ³ CO is the acyl radical of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmoleic acid, stearic acid, isostearic acid, oleic acid , Elaidic acid, petroselinic acid, linoleic acid, linolenic acid, arachic acid, gadoleic acid, behenic acid or erucic acid or their technical mixtures. Fatty acid N-alkylglucamides of the formula (IV) which are obtained by reductive amination of glucose with methylamine and subsequent acylation with lauric acid or Ci2 / i4 coconut fatty acid or a corresponding derivative are particularly preferred. Furthermore, the polyhydroxyalkylamides can also be derived from maltose and palatinose. Mono glyceride, ether) sulfates

Monoglyceride sulfates and monoglyceride ether sulfates, which can also be dried as further anionic surfactants, are known substances which can be obtained by the relevant methods of preparative organic chemistry. The usual starting point for their preparation is triglycerides, which, if appropriate, are transesterified to the monoglycerides after ethoxylation and subsequently sulfated and neutralized. It is also possible to react the partial glycerides with suitable sulfating agents, preferably gaseous sulfur trioxide or chlorosulfonic acid [cf. EP-B1 0561825, EP-B1 0561999 (Henkel)]. If desired, the neutralized substances can be subjected to ultrafiltration in order to reduce the electrolyte content to a desired level [DE-A1 4204700 (Henkel)]. Overviews of the chemistry of the monoglyceride sulfates are, for example, by A.K.Biswas et al. in J.Am.Oil.Chem.Soc. 37, 171 (1960) and F.U. Ahmed J.Am. Oil.Chem. Soc. 67, 8 (1990). The monoglyceride (ether) sulfates to be used in accordance with the invention preferably follow the formula (V),

in which R ⁵ CO stands for a linear or branched acyl radical with 6 to 22 carbon atoms, x, y and z in total for 0 or for numbers from 1 to 30, preferably 2 to 10, and X stands for an alkali or alkaline earth metal. Typical examples of monoglyceride (ether) sulfates which are suitable for the purposes of the invention are the reaction products of lauric acid monoglyceride, coconut fatty acid monoglyceride, palmitic acid monoglyceride, stearic acid monogiyceride, oleic acid monoglyceride and tallow fatty acid monoglyceride and their ethylene oxide adducts or their form of sulfuric acid with sulfuric acid trioxide. Monoglyceride sulfates of the formula (V) are preferably used in which R ⁵ CO represents a linear acyl radical having 8 to 18 carbon atoms. The monoglyceride (ether) sulfates are preferably used as dried granules or powders, which can be obtained, for example, by drying aqueous pastes in a flash dryer.

Betaine

Betaines, which can also be dried as representatives of the amphoteric or zwitterionic surfactants, are known substances which are predominantly prepared by carboxyalkylation, preferably carboxymethylation, of aminic compounds. The starting materials are preferably mixed with halocarboxylic acids or their salts, in particular with sodium chloroacetate condenses, forming one mole of salt per mole of betaine. The addition of unsaturated carboxylic acids, such as acrylic acid, is also possible. Regarding the nomenclature and in particular the distinction between betaines and "real" amphoteric surfactants, reference is made to the contribution by U.PIoog in Seifen-Öle-Fette-Wwachs, 198, 373 (1982). Further overviews on this topic can be found for example by A. O'Lennick et al. in HAPPI, Nov. 70 (1986), S. Holzman et al. in tens. Surf.Det. 23, 309 (1986), R.Bilbo et al. in Soap Cosm. Chem. Spec, Apr. 46 (1990) and P.EIIis et al. in Euro Cosm. 1, 14 (1994). Examples of suitable betaines are the carboxyalkylation products of secondary and in particular tertiary amines which follow the formula (VI)

R ⁷

IR ⁶ -N- (CH ₂ ) _n COOX (VI)

in which R ⁶ for alkyl and / or alkenyl radicals with 6 to 22 carbon atoms, R ⁷ for hydrogen or alkyl radicals with 1 to 4 carbon atoms, R ⁸ for alkyl radicals with 1 to 4 carbon atoms, n for numbers from 1 to 6 and X for a Alkali and / or alkaline earth metal or ammonium. Typical examples are the carboxymethylation products of hexylmethylamine, hexyldimethylamine, octyldimethylamine, Removal cyldimethylamin, dodecylmethylamine, Dodecyldimethyiamin, Dodecylethylmethylamin, CiΣm-Kokosal- kyidimethyiamin, Myristyidimethylamin, cetyldimethylamine, stearyldimethylamine, Stearylethylmethyl- amine, oleyl dimethyl amine, tallow alkyl dimethyl amine Ciθ and technical mixtures thereof. Carboxyalkylation products of amidoamines which follow the formula (VII) are also suitable,

R ⁷

IR ^Q CO-NH- (CH ₂ ) mN- (CH ₂ ) _n COOX (VII)

I.

R ⁸

in which R ⁹ CO represents an aliphatic acyl radical having 6 to 22 carbon atoms and 0 or 1 to 3 double bonds, m represents numbers from 1 to 3 and R ⁷ , R ⁸ , n and X have the meanings given above. Typical examples are reaction products of fatty acids with 6 to 22 carbon atoms, namely caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, elaeostearic acid, gynacholeic acid, arachene acid and erucic acid and their technical mixtures, with N, N-dimethylaminoethylamine, N, N-dimethylaminopropylamine, N, N-diethylaminoethylamine and N, N-diethylaminopropylamine, which are condensed with sodium chloroacetate. Preference is given to using a condensation product of Cs / iβ-coconut fatty acid-NN-dimethylaminopropylamide with sodium chloroacetate. Drying and granulating in the flash dryer

The simultaneous drying and granulation takes place in a horizontally arranged thin-film evaporator with rotating internals, such as that sold by the VRV company under the name "Flashdryer". In simplified terms, this is a tube that has different temperatures across several zones The paste-like feed material, which is metered in via a pump, is thrown against the heated wall by means of one or more shafts, which are provided with blades or shares of flies as rotating internals, on which the drying takes place in a thin layer of typically 1 to For the purposes of the invention, it has proven to be advantageous to apply a temperature gradient from 170 (product inlet) to 20 ° C. (product discharge) to the thin-film evaporator, for example by heating the first two zones of the evaporator to 160 ° C. and the last can be cooled to 20 ° C. Higher drying temperature Temperatures have not proven to be advantageous with regard to the thermal lability when sugar surfactants are also used as additional feedstocks. The thin film evaporator is operated at atmospheric pressure and gassed in countercurrent with air (throughput 50 to 150 m ³ / h). The gas inlet temperature is usually 20 to 30 ° C, the outlet temperature 90 to 110 ° C. The aqueous fatty acid polyglycol ester sulfate pastes which are suitable as starting materials can have a solids content in the range above 20, preferably from 25 to 75% by weight; typically it is 30 to 50% by weight. The throughput is of course dependent on the size of the dryer, but is typically 5 to 15 kg / h. It is advisable to temper the pastes at 40 to 60 ° C during the feed. After drying, it has also proven to be very advantageous to place the granules, which are still approximately 50 to 70 ° C., on a conveyor belt, preferably a vibratory zone, and there, ie within a dwell time of 20 to 60 s, with ambient air at temperatures of cool about 30 to 40 ° C. To further improve the resistance to undesired water absorption, the granules can also be subsequently depleted by adding 0.5 to 2% by weight of silica.

Industrial applicability

The granules obtainable by the process according to the invention can then be mixed with other ingredients of powdered surface-active agents, such as tower powders for detergents. It is also possible without problems to incorporate the powders into aqueous preparations. In fact, no differences in the application properties are observed when using the powders compared to the aqueous starting pastes. Even in bar soaps of the combibar or syndet type, the granules can be easily incorporated, for example together with fatty acids, fatty acid salts, fatty alcohols, starch, polyglycols and the like. Examples

Example 1. The granules were produced in a flash dryer from VRV SpA, Milan / IT. It was a horizontally arranged thin film evaporator (length 1100 mm, inside diameter: 155 mm) with 4 shafts and 22 blades, the distance to the wall of which was 2 mm. The dryer had three separate heating or cooling zones and a total heat exchanger area of 0.44 m ² . The operation was carried out at normal pressure. An aqueous paste of a lauric acid + 1 EO sulfate sodium salt (solids content approx. 50% by weight) with a throughput of 11.5 kg / h was pumped into the thin-film evaporator, its heating zones 1 and 2 had been set to 160 ° C and its cooling zone 3 to 20 ° C. The speed of the rotors was 24 m / s. The flash dryer was gassed with air (approx. 110 m ³ / h); the gas outlet temperature was approx. 65 ° C. The pre-dried, still about 60 ° C hot granules were placed on a vibrating trough (length 1 m), gassed with room air and cooled to about 40 ° C within 30 s. It was then powdered with about 1% by weight of silica (Sipemat® 50 S). A dry, pure-white granulate which was free-flowing and non-clumping even after prolonged storage in the air was obtained, which after incorporation into shampoo formulations showed no differences from a pasty comparative product. The characteristics of the granulate are shown in Table 1.

Table 1:

Characteristics of the Flashdryer granulate

Example 2. Example 1 was repeated with a mixture of 60% by weight lauric acid + 1E0-suifat sodium salt and 40% by weight coconut alkyl oligoglucoside (Plantacare® APG 1200). The temperature in the two heating zones of the flash dryer was raised to 170 ° C. A pure white, free-flowing and non-clumping granulate was also obtained, which had a bulk density of 600 g / l and a residual water content of 0.8% by weight.

Example 3. Example 1 was repeated with a mixture of 60% by weight coconut fatty acid + 1PO sulfate sodium salt and 40% by weight coconut fatty alcohol (Lanette® O, Henkel KGaA). The temperature in the two heating zones of the flash dryer was raised to 170 ° C. A pure white, free-flowing and non-clumping granulate was also obtained, which had a bulk density of 600 g / l and a residual water content of 0.8% by weight.

Example 4. Example 1 was repeated with a mixture of 30% by weight lauric acid + 1EO sulfate sodium salt, 30% by weight coconut fatty acid monoglyceride sulfate and 40% by weight palm kernel fatty acid (Edenor PK®, Henkel KGaA). The temperature in the two heating zones of the flash dryer was raised to 170 ° C. A pure white, free-flowing and non-clumping granulate was also obtained, which had a bulk density of 590 g / l and a residual water content of 0.8% by weight.

Example 5. Example 1 was carried out with a mixture of 30% by weight lauric acid + 1 EO sulfate sodium salt, 30% by weight coconut fatty acid amidopropyibetaine (Dehyton® PK, Henkel KGaA) and 40% by weight palm kernel fatty acid (Edenor PK®, Henkel) KGaA) repeated. The temperature in the two heating zones of the flash dryer was raised to 170 ° C. A pure white, free-flowing and non-clumping granulate was also obtained, which had a bulk density of 600 g / l and a residual water content of 0.8% by weight.

Claims

claims

1. A process for the preparation of water- and dust-free anionic surfactant granules with a high bulk density, in which aqueous pastes of fatty acid polyglycol ester sulfates with a solids content of at least 20% by weight in a horizontally arranged thin-film evaporator with rotating internals except for a residual water content below 2% by weight. % dries at the same time and brings them into lumpy form, whereby a decreasing temperature gradient is applied to the thin-film evaporator from the product inlet to the product outlet, gassed with air in countercurrent and drying takes place exclusively via the heated wall.

2. The method according to claim 1, characterized in that fatty acid polyglycol ester sulfates of the formula (I) are used,

R ¹ COO (AO) _x S0 ₃ X (I)

in the R ¹ CO for a linear or branched, saturated or unsaturated acyl radical having 6 to 22 carbon atoms, x for numbers from 1 to 3 on average and AO for a CH ₂ CH ₂ 0-, CH ₂ CH (CH ₃ ) 0- and / or CH (CH ₃ ) CH ₂ 0 radical and X represents an alkali and / or alkaline earth metal, ammonium, alkylammonium, alkanolammonium or glucammonium.

3. Process according to claims 1 and 2, characterized in that further surfactants are used together with the fatty acid polyglycol ester sulfates, which are selected from the group consisting of alkyl and / or alkenyl oligoglycosides, fatty acid N-alkyl polyhydroxyalkyl amides, monoglyceride (ether) sulfates and betaines and their mixtures.

4. The method according to claim 3, characterized in that alkyl and / or alkenyl oligoglycosides of the formula (II) are used,

R ² 0- [G] _p (II)

in which R ^{2 is} an alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G is a sugar radical having 5 or 6 carbon atoms and p is a number from 1 to 10.

5. The method according to claim 3, characterized in that fatty acid-N-alkylpolyhydroxy alkylamides of the formula (III) are used.

R ⁴

I R3CO-N- [Z] (III)

in which R ³ CO stands for an aliphatic acyl radical with 6 to 22 carbon atoms, R ⁴ for an alkyl or hydroxyalkyl radical with 1 to 4 carbon atoms and [Z] for a linear or branched polyhydroxyalkyl radical with 3 to 12 carbon atoms and 3 to 10 hydroxyl groups.

6. The method according to claim 3, characterized in that one uses monoglyceride (ether) sulfates which follow the formula (V),

CH ₂ 0 (CH ₂ CH ₂ 0) _x -COR ⁵

I CH-0 (CH ₂ CH ₂ 0) _y H (V)

I CH ₂ 0 (CH ₂ CH ₂ 0) _z -S0 ₃ X

in which R ⁵ CO stands for a linear or branched acyl radical with 6 to 22 carbon atoms, x, y and z in total for 0 or for numbers from 1 to 30, preferably 2 to 10, and X stands for an alkali or alkaline earth metal.

7. The method according to claim 3, characterized in that alkyl betaines of the formula (VI) are used,

R ⁷

in which R ⁶ for alkyl and / or alkenyl radicals with 6 to 22 carbon atoms, R ⁷ for hydrogen or alkyl radicals with 1 to 4 carbon atoms, R ⁸ for alkyl radicals with 1 to 4 carbon atoms, n for numbers from 1 to 6 and X for a Alkali and / or alkaline earth metal or ammonium.

8. The method according to claim 3, characterized in that alkylamidobetaines of the formula (VII) are used,

R ⁷

I R9C0-NH- (CH ₂ ) mN- (CH ₂ ) _n C00X (VII)

IR ⁸

in which R ⁹ C0 represents an aliphatic acyl radical having 6 to 22 carbon atoms and 0 or 1 to 3 double bonds, m represents numbers from 1 to 3 and R ⁷ , R ⁸ , n and X have the meanings given above.

9. The method according to claims 1 to 8, characterized in that a temperature gradient of 170 to 20 ° C is applied from the product entry to the discharge.

10. The method according to claims 1 to 6, characterized in that the granules are powdered after cooling with silica.