CA2147207A1 - A process for the simplified purification of useful materials and mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products and associateduseful materials - Google Patents

Abstract

The invention relates to a process for improving the purity and, in particular, the color and odor quality of useful materials and mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products. The process is characterized in that a starting material containing impurities and, in particular, steam-volatile impurities is treated with the superheated steam in finely divided form at normal pressure, bleaching agents optionally being used to produce improvements in color.
In one particular embodiment, the invention relates to the use of the process for drying aqueous preparations of useful materials and/or mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products in a spray drying zone and/or fluidized bed using superheated steam as the drying gas for the simultaneous purification of a starting material containing in particular steam-vola-tile impurities. This purification treatment may be combined with oxidative or reducing bleaching simul-taneously initiated in the treated material to produce light-colored useful materials or mixtures of such useful materials. If desired, ozone may be added in traces to the superheated steam.

Description

H 0517 PCT 2 1 4 7 2 ~ ~
13.7.1993 A process for the simplified purification of useful materials an~ mixturQs of useful materials from the field of wetting agents, detergents ~nd/or clqaning products and associated useful materi~ls Field of the Invention This invention relates to a simplified process for improving the purity and, in particular, the color and odor quality of useful materials and mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products and to associated useful materials, for example from the textile treatment field. The invention seeks in particular to provide a simplified method of substantially improving the odor and/or color of the useful materials or mixtures of useful materials in question without having to resort to the expensive purification processes hitherto applied.
However, the concept of purification in accordance with the invention is not confined to such sensorially perceivable impurities, instead other unwanted impuri-ties from the production and/or processing of usefulmaterials or mixtures of useful materials of the type mentioned can be taken up by the purification process according to the invention and separated from the material to be ultimately obtained.
Prior Art The problems addressed by the present invention are discussed in the following with reference to useful materials from the field of laundry detergents, but is 2147~ l by no means limited to this field.
It is general knowledge that laundry detergents or components used in laundry detergents have to meet relatively stringent purity requirements. Particular significance is attributed in this regard to the odor;
and color requirements which the detergent or detergent mixture is expected to satisfy, as sensorially perceived by the end user. The detergent marketed, for example, as a free-flowing solid material should be light and best pure white in color. A brown or grey product creates the impression of inferior quality and dirti-ness. The odor of the useful material or mixture of useful materials is almost more important. A musty, tallow-like odor results in instinctive rejection. This aspect of product production is complicated by the fact that auxiliaries of the type in question here often have to be stored for long periods in tightly sealed con-tainers under variable external conditions and, when the pack is opened by the consumer, the odor of its contents ZO is perceived very sensitively by the consumer. Musty, tallow-like, rancid or other strong odor impressions result in instinctive rejection although it is only in rare cases that any deterioration in the product proper-ties can be objectively determined.
In addition, experts concerned with the produc-tion of useful materials or mixtures of useful materials of the type targeted by the invention are confronted by further problems of purity which, in the same way as the factors mentioned above, involve considerable expense for the purification of the useful materials or mixtures thereof. The problems involved in the complete removal of alkylene oxide residues (EO and/or PO) and dioxane from the useful materials obtained by alkoxylation, for example nonionic or anionic useful materials, are discussed purely by way of example in the following.

H 517 PCT ~147 2 ~ 7 A complicating factor in this regard is that key useful materials from the field with which the invention is concerned are either based on natural materials or are obtained by synthesis from petroleum-based raw materials. Surfactants are produced by multistage;
processes which, although providing optimal results in regard to the desired component in the particular process stage, also lead to the formation of unwanted impurities, optionally in trace amounts. This is illustrated by way of example in the following with reference to certain anionic surfactant components and certain nonionic surfactant components:
Components based on natural materials of the type in question here generally contain fatty alcohols or fatty alcohol mixtures of natural origin as an oleo-philic component. These fatty alcohols are in turn obtained by reduction of the carboxylic acids obtained from natural oils and fats. These intermediate fatty alcohols are then provided with hydrophilic functional elements. In the case of anionic surfactants for example, a sulfonation and/or sulfation reaction is carried out, generally using S03 or chlorosulfonic acid.
To produce nonionic surfactant components based on fatty alcohols, water-soluble residues are introduced by alkoxylation or by reaction with water-soluble glycose residues. All the reactions take place under demanding process conditions, particularly elevated temperatures.
In general, the starting materials of natural origin are not individual compounds, but rather mixtures such as are provided by nature and such as can be obtained from such mixtures by simple separation processes.
It is known that stringent requirements in regard to the purity of the starting materials, the inter-mediate reaction products and the required end products arise out of these preconditions. The cost of useful H 5~ a ~ 4 materials of the type in question and mixtures thereof is determined to a large extent by the technical effort involved in the particular purification stage.
Useful materials and mixtures of useful materials for use in wetting agents, detergents and/or cleaning;
products may be present either as liquid components or in the form of pourable granules. They are generally obtained by drying intermediately obtained aqueous preparations of this class of compounds. For decades, preparations such as these have been universally spray-dried on an industrial scale. Hot air or mixtures of air and hot combustion gases are used as the drying gas stream.
Applicants have worked extensively on the pos-sibility of applying the principle of drying with superheated steam to useful materials and mixtures thereof for use in wetting agents, detergents and/or cleaning products. It has surprisingly been found that the advantages of drying with superheated steam, partic-ularly in regard to ecology and energy, may also be used for the present basically very sensitive field of application or product field. Thus, DE-A 40 30 688 describes a process for recovering fine-particle, solid or free-flowing useful materials or mixtures thereof for wetting agents, detergents and/or cleaning products from water-containing preparations thereof using superheated steam as the drying hot gas stream. In this process, drying of the particulate material is terminated before it is endangered by heat.
Particular emho~;ments of and improvements in such drying processes using superheated steam as the hot gas stream and their application to useful materials and mixtures thereof for wetting agents, detergents and/or cleaning products are disclosed in a number of other earlier applications in applicants' name, cf. in par-ticular earlier German patent applications DE-P 42 04 035.3, DE-P 42 04 090.6, DE-P 42 06 050.8, DE-P 42 06 521.6, DE-P 42 06 495.3, DE-P 42 08 773.2 and DE-P 42 09 432.1.
A particularly important further development is;
concerned with the unexpected advantageous product properties exhibited by a solid pourable and free-flowing starting material obtained by drying with superheated steam. A description is given as to how a microporous structure can be developed and fixed in a starting material initially obtained by drying with superheated steam and - building on this - as to how mixtures of useful materials from the field in question can be formulated in a hitherto unknown manner, cf.
applicants' earlier German patent application P 42 34 376.3.
The teaching according to the invention described hereinafter for the production of useful materials of the type mentioned above and mixtures thereof with greater purity for distinctly less effort builds on the experience and working principles according to the above-cited DE-A 40 30 688 and the earlier applications mentioned. Accordingly, the disclosure of that document and the earlier applications in question are hereby specifically included as part of the disclosure of the present invention which is to be understood in combina-tion with the further observations and working prin-ciples described in the following.
The teaching according to the invention is based on the surprising observation that the treatment of a starting material as disclosed in the description of the present invention not only leads to drying under the conditions of the treatment with superheated steam, the method used for this treatment may also be used with particular advantage for removing unwanted constituents 21~7~

from the useful materials and mixtures thereof. Thus, it is possible to remove relatively small or even relatively large quantities of foreign substances from the starting material to be purified by a comparatively S brief treatment in accordance with the invention. ~ot~
only can olfactorily troublesome components, for ex-ample, be removed from the starting material, the teaching according to the invention also includes -where necessary - a simultaneous bleaching treatment of the starting mixture in its technical actions. These possibilities provide for a simplified purification process for the production of high-quality useful materials and mixtures thereof by which the purity requirements can be satisfied more easily and, hence, less expensively.

Doscription of tho Invention In a first embodiment, therefore, the present invention relates to a process for improving the purity and, in particular, the color and odor quality of useful materials and mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products or related useful materials (hereinafter refer-red to as the "starting material"), characterized inthat an impurity-containing starting material is treated with superheated steam under the conditions described in detail hereinafter. According to the invention, bleach-ing agents are used in the starting material to obtain improvements in color. In one important embodiment of the process according to the invention, the impurity-containing starting material is e~c~^~ to the treatment with superheated steam in fine-particle form and, in particular, under normal pressure. Preferably, water-containing mixtures of the starting material to be 2147~07 purified are subjected to the treatment with superheatedsteam. At the same time, drying may be carried out in the superheated steam atmosphere.
In one embodiment, therefore, the teaching according to the invention relates to the use of the;
process for the drying of water-containing preparations of useful materials and/or mixtures of useful materials from the field defined in accordance with the invention in a spray drying zone and/or in a fluidized bed using superheated steam as the drying gas for the simultaneous purification of a starting material containing in particular steam-volatile impurities.
In important embodiments, the invention thus makes use of the fact that a large number of unwanted impurities such as are encountered in the field in question show comparatively high volatility, particular-ly in a steam-filled atmosphere, by comparison with the final components to be ultimately obtained in the useful material or mixture of useful materials. This not only applies to low molecular weight, but difficult-to-remove residues, such as ethylene oxide and/or propylene oxide and also dioxane, from corresponding reaction mixtures, unwanted impurities of relatively high molecular weight, such as unreacted fatty alcohols or fatty alcohol mix-tures or partial oxidation products derived therefrom,more particularly lower carbonyl cu~ounds, such as fatty aldehydes, can also be effectively removed in an inert steam atmosphere from mixtures with the desired pure materials or pure mixtures of the starting materi-al.
Purification stages in the production of usefulmaterials of the type in question and mixtures thereof using steam are known per se. The support provided by the use of steam in the removal of troublesome impuri-ties in relatively large or relatively small quantities 2 1 4~ 7 is also known. For example, the removal of unreactedfatty alcohol in the production of nonionic surfactant components from the class of alkyl polyglycosides (APG) is described in EP-B 0 092 876 (Procter & Gamble). In general terms, however, the purification of useful;
materials or mixtures thereof based on natural substan-ces by so-called steaming is another known method of removing above all troublesome trace substances from the material to be purified (cf. EP-B 0 283 862, Henkel).
The invention goes beyond these known proposals.
The starting material to be purified is treated under the effect of superheated steam which was described for the first time in DE-A 40 30 688 as a drying gas for useful materials and mixtures of useful materials of the type in question. The drying process disclosed in DE-A
40 30 688 may be used in the context of the teaching according to the invention, although the teaching according to the invention goes beyond this. The invention now makes it possible for the first time to subject an impurity-containing starting material to such a drying process and, at the same time, to obtain the highly purified end products required. It is clear that the multistage production of useful materials of the type targeted by the invention can be considerably simplified in this way. Depending on the particular circumstances, substantial savings can be made in the intermediate purification of precursors or end products before they are finally dried to form the desired end product. Accordingly, compared with conventional spray drying and/or fluidized bed drying with a hot gas phase based on air and combustible gases, the invention provides new ways of obtaining high-quality useful materials and useful material mixtures of the type in question.
The teaching according to the invention is of particular importance in connection with the production of useful materials which are free from unwanted odor emissions. Irrespective of this or at the same time, however, the teaching according to the invention also enables the color of the end products to be improved to;
the extent that they are either light of white in color.
The removal of the olfactorily troublesome foreign components is the immediate result of the treat-ment of the material in the superheated steam phase. In the preferred embodiment of the invention, water-con-taining mixtures of starting materials are introduced in finely divided form into a zone through which super-heated steam is passed. The following reaction sequence then occurs: the drop of water-containing liquid gener-ally introduced at temperatures below the evaporationtemperature of the water under the working conditions results in the immediate condensation of more water on the drop of liquid. At the same time, the heat of condensation passes over to the droplet-like material.
This dilution process continues until the temperature of the material introduced corresponds to the evaporation temperature of the water under the working conditions.
In general, therefore, this temperature is of the order of lOO C. When the evaporation temperature is reached in the drop, the drop as a whole is dried in the one-component water/steam system without the formation of the rigid outer shell formed in the conventional drying process. This drying process is described in detail in earlier German patent application P 42 34 376.3, to which reference is again expressly made. The outcome of this drying process in superheated steam is the highly porous inner structure - described in the earlier application - of the dry material which is solid at the drying temperature. This highly porous structure is utilized in the teaching according to the invention.

~14.?~7 The basically volatile and, in particular, steam-volatile impurities are not trapped in the drop and prevented from evaporating, instead they are capable of passing into the gas phase during the drying process or even thereafter under the effect of the superhea~ed;
steam and are discharged with the superheated steam.
The purified material remains behind. A corresponding simplification of the removal of foreign components is guaranteed in the treatment of liquid components in the superheated steam phase.
The possibility of removing foreign components discussed herein mainly affects the removal of unwanted odor-emitting components and the removal of comparative-ly light volatile or steam-volatile components of neutral odor. The teaching of the invention goes beyond this insofar as colored impurities from a corresponding-ly contaminated starting material can be removed at the same time. To this end, the teaching according to the invention is characterized by the use of bleaches in the starting material. Suitable bleaches are both oxidative and reducing bleaches known per se. Typical examples of oxidative bleaches are hydrogen peroxide, persalts, such as percarbonates, perborates, persulfates, hypochlorite salts, more particularly alkali metal hypochlorite, and the like. So-called bleach activators known from the field of washing and textile auxiliaries and described in detail hereinafter may be used together with the oxidative bleaching agents, as known per se.
Examples of reducing bleaching components are, in particular, compounds of this class which do not lead to unwanted secondary reactions in the presence of the superheated steam. Examples of such compounds are phosphorus compounds, more particularly hypophosphorous acid and its salts, more particularly alkali metal and/or alkaline earth metal salts.

21~7207 Bleaches may be added to the starting mixtures to be purified in the particular quantity required.
Normally, quantities of up to about 10% by weight are sufficient, even for comparatively serious contamina-tion, quantities of from about 0.5 to 5% by weight;preferably being added to the starting material to be bleached (percentages by weight based on the particular component to be bleached or rather the corresponding multicomponent mixture).
The need for bleaching and/or the need for additional lightening will make corresponding measures of the teaching according to the invention desirable when individual components are more or less heavily discolored - normally above all to brown from individual synthesis steps - and/or when the multicomponent mixture as a whole, for example a laundry detergent or a corre-sponding tower powder for the production of laundry detergents, is to be additionally lightened in color.
Corresponding discolorations of individual components are known problem factors in the sulfonation and/or sulfation of oleophilic components in the production of surface-active compounds of the anionic surfactant type.
Comparatively speaking, however, corresponding color problems can also arise in the production of surface-active components containing quaternary ammonium groupsas used, for example, in fabric softeners for the treat-ment of laundry after washing. Another known example of the occurrence of unwanted brown discoloration is to be found in the class of APG compounds used as nonionic surfactants. The glucose content in particular of this class of compounds leads to unacceptable brown dis-coloration on account of its temperature sensitivity.
The teaching according to the invention is particularly helpful here in enabling color to be lightened. The critical temperature range beyond which browning norm-4~ r~

ally occurs in the APG-containing material can be reliably avoided by correspondingly controlling the temperature of the superheated steam phase. At the same time, the preferred form of working up according to the invention via a fine-particle starting material in the;
gas phase of the superheated steam ensures that no caking and hence no local overheating in the APG-con-taining material can occur on metal surfaces. Another known example of problematical discoloration in surfac-tan's is to be found in anionic surfactants based on ~-s-~ ~ituted ester sulfonates, more particularly the corresponding methyl ester sulfonate salts (MES), and the disalts of the alpha-sulfofatty acids derived therefrom by ester saponification.
In one particular embodiment of the invention, the starting material to be purified is treated with a superheated steam phase to which traces of ozone have been added. This addition of ozone can be important in particular in connection with improvement of the olfac-tory property spectrum of the starting material to be treated. Even very small amounts of ozone in the superheated steam can lead to a perceptible improvement in the odor of the material. According to the inven-tion, the ozone is preferably added in quantities in the lower ppm range, based on the particular quantity of vapor removed from the drying circuit of the superheated steam which corresponds to the water evaporated during the process and introduced with the starting material to be purified. The quantity of ozone added preferably amounts to no more than about 1 ppm and, in particular, is less than 0.5 ppm. In a particularly preferred embodiment, the ozone is added in a quantity of from about 0.05 to 0.2 ppm. The basis for these ppm figures is the same as mentioned above. The ozone may be added to the circulating steam, preferably immediately before the superheated steam is returned to the drying zone, and/or directly to the drying zone.
In one preferred embodiment, the treatment according to the invention is applied to an impurity-containing starting material which is capable of with-;
standing an at least brief increase in temperature to the evaporation temperature of the water under the process conditions, more particularly to temperatures in the range from about 90 to llO C, with virtually no damage. Although liquid and/or solid starting materials are equally suitable for this purpose, particularly good results can often be obtained with materials which, in their dried state, are present as solids at temperatures of 90 to llO-C and which, as the starting material to be purified, are unsatisfactory above all in odor and/or color.
In another preferred embodiment, flowable and sprayable aqueous solutions, emulsions and/or suspen-sions of the impure starting material are subjected to the treatment with the superheated steam. In this embodiment, at least partial drying of the water-con-taining flowable materials can be combined with the treatment according to the invention in the spray drying zone and/or in the fluidized bed.
In other respects, the parameters for the treat-ment of the starting material with superheated steam correspond to the disclosure of DE-A 40 30 688 and applicants' earlier applications cited in this connec-tion. Particulars of the composition of suitable useful materials and mixtures of useful materials for wetting agents, detergents and/or cleaning products can be found in particular in earlier German patent application P 42 34 376.3. This document describes useful materials or mixtures of useful materials of the type in question which are solid at temperatures in the range from 100 to llO-C and preferably at temperatures in the range up to about 120-C and of which the plasticity and surface tackiness are limited to such an extent that there is no significant adhesion of the particles to one another and/or within their open-pored inner structure, even;
under the conditions of exposure to the superheated steam. In important embodiments, the teaching according to the invention makes use of these elements of the teaching of the earlier application. Both individual useful materials and also carrier beads of mixtures of useful materials as defined in the earlier application and, finally, the useful materials used to impregnate these carrier beads may be, or may already have been, subjected to purification in accordance with the teach-ing of the invention.
The purification process according to the inven-tion is carried out at normal pressure or at only slightly increased or only slightly reduced pressures.
Thus, preferred deviations from normal pressure in either direction are pressure deviations of up to about 0.15 ~ar, preferably no more than about 0.1 bar and, more preferably, no more than 0.01 to 0.05 bar. The application of slightly increased internal pressures of the system rules out any unwanted penetration of oxygen-containing ambient air and, hence, unwanted secondary reactions with the useful material to be treated, even where damaged areas are present. The superheated steam is normally used at temperatures in the range from 100 to 450 C and preferably at temperatures in the range from about 115 to 350 C. Further particulars in this regard can be $ound in applicants' above-cited patents and patent applications relating to the field in ques-tion. The closed circuits required for the use of superheated steam afford a significant advantage so far as the treatment according to the invention is con-2 1 4 7 2 0 ~

cerned. The stream or partial stream of superheated steam laden with the impurities discharged is not let off into the atmosphere as such, but instead is sub-jected to condensation. Most of the impurities dis-charged pass into the liquid and/or solid phase during this condensation step. Residues remaining in the gas phase may be suitably worked up, for example by burning, together with the gas phase separated from this subse-quent condensation step. Depending on their quality, the discharged quantities of former starting materials of the material to be purified, which accumulate during the condensation of the vapor stream removed from the circuit, may be destroyed without causing any damage or returned to suitable preliminary stages of the produc-tion of the particular useful materials. It is possible in this way to purify the particular starting materials completely safely, without any environmental damage and with optimum economy, even when hitherto typical costly steps, particularly in the form of distillation-based purification and the like, have not been carried out with the hitherto usual intensity, if at all, in the production of the material to be purified.
Without any claim to completeness, further observations on useful materials and auxiliaries from the specialist field in question are presented in the following, again with specific reference to the general knowledge of the expert.

al) Suitable anionic surfactants of sulfate or sulfonate structure are, for example, alkyl benzenesulfonates, alkane sulfonates, olefin sulfonates, alkyl ether sulfonates, glycerol ether sulfonates, ~-methyl ester sulfonates, sulfofatty acids, alkyl sulfates, fatty alcohol ether sulfates, glycerol ether sulfates, hydroxy 2147~7 mixed ether sulfates, monoglyceride (ether)sul-fates, fatty acid amide (ether)sulfates, sulfo-succinates, sulfosuccinamates, sulfotriglycer-ides, isethionates, taurides and alkyl oligo-glucoside sulfates. If the anionic surfactants;
contain polyglycol ether chains, they may have a conventional homolog distribution, although they preferably have a narrow-range homolog distribu-tion.
a2) Suitable anionic surfactants of carboxylate structure are, for example, soaps of natural or synthetic, preferably saturated fatty acids.
Soap mixtures derived from natural fatty acids, for example coconut oil fatty acid, palm kernel oil fatty acid or tallow fatty acid, are particu-larly suitable. Soap mixtures of which 50 to 100% consist of saturated C121g fatty acid soaps and 0 to 50% of oleic acid soaps are preferred.
Amide soaps, ether carboxylic acid salts and sarcosinates are also suitable.

a3) In the context of the present invention, "anionic surfactants of sulfate, sulfonate and/or carboxy-late structure" are also understood to include amphoteric or zwitterionic surfactants which contain at least one of these groups in the molecule. Typical examples are alkyl betaines, alkyl amidobetaines, aminopropionates, aminogly-cinates, imidazolinium betaines and sulfobeta-nes .
The anionic surfactants may be present in the form of their sodium, potassium and ammonium salts and also in the form of soluble salts of organic bases, such as mono-, di- or triethanol-2147~07 amine. The substances mentioned are all known compounds. Particulars of their structure and production can be found in relevant synoptic works, cf. for example J. Falbe (ed.), "Surfac-tants in Consumer Productsn, Springer Verlag,;
Berlin, 1987, pages 54 to 124 or J. Falbe (ed.), "Ratalysatoren, Tenside und Mineraloladditive", Thieme Verlag, Stuttgart, 1978, pages 123 to 217.

10 b) Nonionic surfactant compounds in the context of the teaching according to the invention may perform various functions as useful materials.
on the one hand, they are washing-active com-ponents which cooperate synergistically with the anionic surfactants in the usual way. On the other hand, however, greater significance can also be attributed to the class of nonionic surfactants, for example in the form of disper-sants, structure breakers and the like.
Nonionic surfactant compounds may be liquid or solid at room temperature, as known per se.
With reference to general specialist knowledge, the following nonionic surfactant compounds are mentioned by way of example:
bl) The liquid alcohol ethoxylates used as nonionic surfactants are derived, for example, from primary alcohols preferably containing 9 to 18 carbon atoms and, on average, 1 to 12 mol ethy-lene oxide in which the alcohol radical may be linear or branched, more particularly methyl-branched in the 2-position, or may contain mix-tures of linear and methyl-branched radicals such as are typically present in oxoalcohol radicals.
However, linear radicals of alcohols of native ?, ~. 4~

origin containing 12 to 18 carbon atoms, for example of coconut oil fatty alcohol, tallow fatty alcohol or oleyl alcohol, are particularly preferred.
Cl2~ alcohols containing 3 EO or 4 EO, ~
alcohols containing 7 EO, Cl3l5 alcohols con-taining 3 EO, 5 EO, 7 EO or 8 EO, Cl2l8 alcohols containing 3 EO, 5 EO or 7 EO and mixtures thereof, such as mixtures of Cl2l4 alcohol con-taining 3 EO and Cl2l8 alcohol containing 5 EO, can be particularly preferred.
The degrees of ethoxylation mentioned are statistical mean values which, for a special product, may be a whole number or a broken number. Preferred alcohol ethoxylates have a narrow-range homolog distribution (narrow-range ethoxylates, NRE). Alcohol ethoxylates contain-ing on average 2 to 8 ethylene oxide groups are particularly preferred.
b2) Other suitable nonionic surfactants are alkyl oligoglycosides corresponding to general formula (I):

Rl-O-[G~

in which Rl is a primary linear or 2-methyl-branched aliphatic radical containing 8 to 22 and preferably 12 to 18 carbon atoms and G stands for a glycose unit containing 5 or 6 carbon atoms, preferably glucose. The degree of oligomeriza-tion x, which indicates the distribution of mono-glycosides and oligoglycosides, is a number of 1 to 10 and, for example, lies in the range from about 1.2 to 4 and, more particularly, 1.2 to 2.

b3) Nonionic surfactants of the amine oxide type, for example N-coconut oil alkyl-N,N-dimethyl amine oxide and N-tallow alkyl-N,N-dihydroxyethyl amine oxide, and of the fatty acid alkanolamide type may also be suitable. The quantity in which;
these nonionic surfactants are present is prefer-ably no more than that of the ethoxylated fatty alcohols and, in particular, no more than half that quantity.
b4) Other suitable surfactants are polyhydroxyfatty acid amides corresponding to formula (II):

R2CO-N-(Z) (II) in which R2CO is an aliphatic acyl radical containing 6 to 22 carbon atoms, R3 is hydrogen, an alkyl or hydroxyalkyl radical containing 1 to 4 carbon atoms and (Z) is a linear or branched polyhydroxyalkyl radical containing 3 to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid amides are known substances which may normally be obtained by reductive amination of a reducing sugar with ammonia, an alkyl amine or an alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride. Processes for their production are described in US 1,985,424, 2,016,962 and 2,703,798 and in International patent application WO 92/06984 (Procter &
Gamble). The polyhydroxyfatty acid amides are preferably derived from reducing sugars contain-ing 5 or 6 carbon atoms, more particularly from 4~2Ql H 5~7 PCT 20 glucose. Accordingly, the preferred polyhydroxy-fatty acid amides are fatty acid-N-alkyl gluca-mides corresponding to formula (III):

l l R2CO-N-CH2-CH-CH-CH-CH-CH2OH (III) I

OH
Preferred polyhydroxyfatty acid amides are fatty acid-N-alkyl glucamides corresponding to formula (III), in which R3 is hydrogen or an amine group and R2CO is the acyl radical of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselic acid, linoleic acid, linolenic acid, arachic acid, gadoleic acid, behenic acid or erucic acid or technical mixtures thereof. Fatty acid-N-alkyl glucamides (III) obtained by reduc-tive amination of glucose with methyl amine and subsequent acylation with lauric acid or C~
coconut oil fatty acid or a corresponding deriva-2S tive are particularly preferred.

c) Suitable organic and inorganic builders which may be used in mixtures of useful materials to be purified in accordance with the invention are soluble and/or insoluble components showing a mildly acid, neutral or alkaline reaction which are capable of precipitating or complexing calcium ions.

35 cl) Suitable and, in particular, ecologically safe builders, such as finely crystalline synthetic water-containing zeolites of the NaA type, which have a calcium binding power of 100 to 200 mg CaO/g (as determined in accordance with DE-A 24 12 837), are preferably used. Their average;
particle size is normally in the range from 1 to 10 ~m (as measured with a Coulter Counter, volume distribution). Suitable substitutes or partial substitutes for phosphates and zeolites are crystalline, layer-form sodium silicates corre-sponding to general formula (IV):

NaMSi~O2~1 Y H2O (IV) in which M is sodium or hydrogen, x is a number of 1.9 to 4 and y is a number of 0 to 20, prefer-red values for x being 2, 3 or 4. Crystalline layer silicates such as these are described, for example, in European patent application EP-A 0 164 514. Preferred crystalline layer silicates (IV) are those in which M is sodium and x has a value of 2 or 3. Beta- and delta-sodium disili-cates corresponding to formula (V):

Na2Si2O5 Y H2O (V) are particularly preferred, beta-sodium disili-cate being obtainable, for example, by the process described in German patent application DE-A 39 39 919.

c2) Other suitable builder components, which may be used in particular together with the zeolites, are layer compounds of the hydrotalcite type and (co)polymeric polycarboxylates, such as polyacry-21~1Z~7 lates, polymethacrylates and, in particular, copolymers of acrylic acid with maleic acid, preferably those of 50% to 10% maleic acid. The relative molecular weight of the homopolymers is generally in the range from 1,000 to 100,~00 while the relative molecular weight of the copolymers is generally in the range from 2,000 to 200,000 and preferably in the range from 50,000 to 120,000, based on free acid. A par-ticularly preferred acrylic acid/maleic acid copolymer has a relative molecular weight of 50,000 to 100,000. Suitable, but less preferred compounds of this class are copolymers of acrylic acid or methacrylic acid with vinyl ethers, such lS as vinyl methyl ethers, in which the acid makes up at least 50%. Other suitable compounds of this class are polyacetal carboxylic acids, for example of the type described in US 4,144,226 and US 4,146,495, and also polymeric acids which are obtained by polymerization of acrolein and subse-quent disproportionation with alkalis and which are made up of acrylic acid units and vinyl alcohol units or acrolein units.

25 c3) Other suitable organic builders are the polycar-boxylic acids preferably used in the form of their sodium salts, such as citric acid, ethylene diamine tetraacetic acid (EDTA) and nitrilotri-acetic acid (NTA), providing their use is not ecologically objectionable.

c4) Other suitable ingredients of the wetting agents, detergents and/or cleaning products are water-soluble inorganic alkalizing agents, such as bicarbonates, carbonates or silicates; alkali 21~72~7 metal carbonate and alkali metal silicate, above all sodium silicate with a molar ratio of Na20 to SiO2 of 1:1 to 1:4.0, are particularly suitable.

5 d) The other detergent ingredients include redeposi-;
tion inhibitors (soil suspending agents), foam regulators, bleach activators, optical brighten-ers, fabric softeners, dyes and fragrances and also neutral salts. Other important detergent ingredients are, for example, bleaches and enzymes. The extent to which these components need the purification treatment according to the invention will have to be determined from case to case. In the formulation of useful materials or mixtures of useful materials for the field of application according to the invention, these components are added last - usually separately -to the mixtures of useful materials used. An exception may be the bleach activators which, as mentioned above, may also be used in the mixtures of useful materials as auxiliaries for improved bleaching under the conditions according to the invention during the actual treatment with superheated steam. Nevertheless, the subsequent introduction of additional quantities of bleach activators may also be advisable in such a case for a mixture of useful materials, for example in the form of a laundry detergent.

30 dl) Examples of bleach activators, which are intended to lead to an improved bleaching effect at washing temperatures of 60 C and lower, are N-acyl or O-acyl compounds which form organic peracids with H202, preferably N,N'-tetraacylated diamines, such as N,N,N',N'-tetraacetyl ethylene 214~ 20rl diamine, and also carboxylic anhydrides and esters of polyols, such as glucose pentaacetate.

d2) The function of redeposition inhibitors is to keep the soil detached from the fibers suspended;
in the liquor and thus to prevent discoloration.
Suitable redeposition inhibitors are water-soluble, generally organic colloids, such as for example the water-soluble salts of polymeric carboxylic acids, glue, gelatine, salts of ether carboxylic acids or ether sulfonic acids of starch or cellulose or salts of acidic sulfuric acid esters of cellulose or starch. Water-soluble polyamides containing acidic groups are also suitable for this purpose. Soluble starch preparations and other starch products than those mentioned above, for example degraded starch, aldehyde starches etc., may also be used. The same applies to polyvinyl pyrrolidone (PVP).
d3) Suitable foam regulators are combinations of suitable surfactants. A reduction can also be obtained by additions of non-surface-active organic compounds. In many cases, reduced foaming, which is desirable for washing machines, is achieved by combining various types of surfac-tants, for example sulfates and/or sulfonates with nonionic surfactants and/or with soaps. In the case of soaps, the foam-inhibiting effect increases with the degree of saturation and the carbon chain length of the fatty acid component.
Accordingly, suitable foam-inhibiting soaps are soaps of natural and synthetic origin which have a high percentage content of Cl82~ fatty acids.
3S Suitable non-surface-active foam inhibitors are 2I ~ 72~ ~

organopolysiloxanes and mixtures thereof with microfine, optionally silanized silica, paraf-fins, waxes, microcrystalline waxes and mixtures thereof with silanized silica. Bisacylamides derived from C12-20 alkyl amines and C2-6 dicar-;
boxylic acids may also be used. Mixtures of various foam regulators, for example mixtures of silicones and paraffins or waxes, may also be used with advantage. The foam regulators or inhibitors are preferably adsorbed to a granular carrier substance soluble or dispersible in water.

d4) Suitable optical brighteners are derivatives of diaminostilbene disulfonic acid or alkali metal salts thereof, for example salts of 4,4'-bis-(2-anilino-4-morpholino-1,3,5-triazin-6-ylamino)-stilbene-2,2'-disulfonic acid or compounds of similar structure in which the morpholino group is replaced by a diethanolamino group, a methyl-amino group, an anilino group or a 2-methoxy-ethylamino group. Brighteners of the substituted 4,4'-distyryl diphenyl type, for example the com-pound 4,4'-bis-(4-chloro-3-sulfostyryl)-diphenyl, may also be present. Mixtures of the brighteners mentioned above may also be used.

d5) Further improvements in whiteness can be obtained in known manner if, in addition to the usual optical brighteners, the detergents also contain small quantities of a blue dye. A particularly preferred dye is Tinolux (a product of Ciba-Geigy).

35 e) In order to improve the rapid dissolution of ~4~lQ~l basically poorly soluble components, for example corresponding anionic surfactants, such as FAS, even at room temperature or only moderately elevated temperatures, it can be important to use so-called structure breakers which, in many;
cases, are extremely effective in only very small quantities, based on anionic surfactant. Even the purification of such structure breakers as these by the process according to the invention can lead to important improvements.

el) Suitable structure breakers may be selected from a number of both solid and liquid substances which are hydrophilic, soluble in water or dis-persible in water. Suitable structure breakers are, for example, lower polyalkylene glycols which are derived from linear or branched glycols containing 2 to 6 carbon atoms, preferably polyethylene glycol or polypropylene glycol, and which have a relative molecular weight of 200 to 12,000. Particularly preferred structure break-ers are polyethylene glycols having a relative molecular weight of 200 to 4,000, liquid poly-ethylene glycols having a relative molecular weight of up to 2,000 and, more particularly, in the range from 200 to 600 showing particularly advantageous properties.

e2) The sulfates and, in particular, disulfates of lower polyalkylene glycols, more particularly polyethylene glycol and 1,2-propylene glycol, are also suitable. Sulfates and/or disulfates de-rived from polyethylene glycols and polypropylene glycols having a relative molecular weight of 600 to 6,000 and, more particularly, in the range 214 7~ 0 7 from 1,000 to 4,000 are particularly preferred.
The disulfates generally originate from polygly-col ethers which can be formed in the alkoxyla-tion of alcoholic components through the presence of traces of water.

e3) Another group of suitable structure breakers consists of the water-soluble salts of monosuc-cinates and/or disulfosuccinates of lower poly-alkylene glycols. Of particular significance in this regard are the corresponding polyethylene glycol and polypropylene glycol compounds, sulfosuccinates and disulfosuccinates of polygly-col ethers having a relative molecular weight in the range from 600 to 6,000 and, more particular-ly, in the range from 1,000 to 4,000 being particularly preferred.
Salts and preferably alkali metal salts, more particularly sodium and potassium salts, and also ammonium salts and/or salts of organic amines, for example triethanolamine, are suitable for the use of the anionically modified polyalky-lene glycols as structure breakers. The most important salts for practical application are the sodium salts of the sulfates, disulfates, sulfo-succinates and disulfosuccinates of polyethylene glycol and polypropylene glycol.
Mixtures of the polyalkylene glycols and their anionically modified derivatives in any ratio are also preferably used. A mixture of polyalkylene glycol and the sulfosuccinates and/or disulfosuccinates of the polyalkylene glycols is particularly preferred. However, a mixture of polyalkylene glycol and the corre-sponding sulfates and/or disulfates and a mixture O~

of polyalkylene glycol and the corresponding sulfates and/or disulfates and also the corre-sponding sulfosuccinates and/or sulfodisuccinates are also suitable.

e4) Other suitable structure breakers preferably used in accordance with the invention are the adducts of approx. 20 to approx. 80 mol ethylene oxide with 1 mol of an aliphatic alcohol essentially containing 8 to 20 carbon atoms which are well known ingredients of detergents and cleaning products. Of particular importance are the adducts of 20 to 60 mol and, more particularly, 25 to 45 mol ethylene oxide with primary alco-hols, such as for example coconut oil fatty alcohol or tallow fatty alcohol, with oleyl alcohol, with oxoalcohols or with secondary alcohols containing 8 to 18 and preferably 12 to 18 carbon atoms. Examples of particularly preferred structure breakers from the group of highly ethoxylated alcohols are tallow fatty alcohol containing 30 EO and tallow fatty alcohol containing 40 EO. It is also preferred to use mixtures containing highly ethoxylated alcohols, for example mixtures of tallow fatty alcohol containing 40 EO and water or mixtures of tallow fatty alcohol containing 40 EO and polyethylene glycol having a relative molecular weight of 200 to 2,000.
e5) Other suitable structure breakers are ethoxy-lated, vicinal internal alkanediols or 1,2-alkanediols with a carbon chain containing 8 to 18 carbon atoms and 4 to 15 mol ethylene oxide per mol diol. Only one of the two OH groups or 21472~

both OH groups of the alkanediol can be ethoxy-lated.

e6) Other suitable structure breakers are modified nonionic surfactants terminated by an acid group.
The nonionic surfactants in question are nonionic surfactants, more particularly fatty alcohols, in which one OH group has been converted into a group containing a carboxyl group. Accordingly, nonionic surfactants terminated by an acid group include esters or partial esters of a nonionic surfactant with a polycarboxylic acid or a polycarboxylic anhydride. Examples of acid-terminated nonionic surfactants are the known polyether carboxylic acids and esters or semi-esters of C~l~ alcohols with succinic anhydride, maleic anhydride, maleic acid or citric acid.

e7) Another group of suitable structure breakers consists of alkylene glycol monoalkyl ethers corresponding to general formula (VI):

R40(CH2CH2o)nH (VI) in which R4 is a radical containing 2 to 6 carbon atoms and n is a number of 1 to 8. Examples of this group of additives are ethylene glycol monoethyl ether and diethylene glycol monobutyl ether.
f) Important components for the starting mixtures or rather useful materials according to the inven-tion are so-called cationic active substances from the field of wetting agents, detergents and cleaning products or the associated auxiliaries.

2~47~7 Of particular importance in this regard are the quaternary ammonium compounds which are widely used, for example, as fabric-softening components and which contain at least one and preferably two relatively long-chain alkyl radicals at a quater--nary nitrogen atom.
So-called esterquats which show relatively high ecological compatibility and which - start-ing from a trialkanolamine, typically triethanol-amine - contain relatively long-chain fatty acid components bound in ester form are now of par-ticular importance in this regard. Mixtures of mono-, di- and triesters are normally present, the monoester content being, for example, from 15 to 25 mol-%, the diester content from 40 to 50%
and the triester content making up the remainder (for relevant literature, see for example EP-A
239 910 or DE-A 19 35 493). Esterquats according to these and other literature references (for example EP-A 0 293 953 and EP-A 0 309 052) are reaction products of triethanolamine or ethoxy-lated monoethanolamine with mixtures of saturated and unsaturated C6z8 fatty acids. The reaction product initially formed is subsequently quater-nized with dimethyl sulfate. Further particulars of the class of compounds in question can be found in DE-A 37 10 064 (EP-A 0 284 036) and in EP-A 0 295 385.

The following Examples are intended to illustrate the invention without limiting it in any way.

2 1 ~ 7 h 0 7 ~r~ples ~mple 1 In an experimental pilot-plant spray drying tower of the "minor production" type manufactured by Niro-;
Atomizer, a slurry of the sodium salt of a Cl6/l8 fatty alcohol sulfate was converted by addition of sodium carbonate into a free-flowing surfactant powder. The mixing ratio between the anionic surfactant and sodium carbonate was 4:1, based on dry matter.
The aqueous slurry of the fatty alcohol sulfate used is a white to pale yellow firm paste having the following characteristic data:

Washing-active substance (Epton): 54 - 58%
Fatty alcohol sulfate: 53 - 55%
Unsulfonated: 1 - 3%
NaCl content: 1%
Na2S0, content: 2%
pH value (3% aqueous preparation): 10 - 11.5 After the aqueous soda solution had been added, the slurry had a dry matter content of 47.7% by weight.
The slurry is sprayed through a two-component nozzle (propellent gas nitrogen) and dried in countercurrent with superheated steam. The following operating para-meters were established for drying with superheated steam:

Steam entry temperature: 250 C
Steam exit temperature: 175 - 180-C
Reduced pressure in tower: 16 mbar Feed pump pressure: 5.5 bar Feed temperature: 80 C
Feed input: 12 kg/h 2~

Steam input: 350 m3/h Propellent gas for the two-component nozzle quantity: 3.3 m3/h pressure: 0.2 bar The product obtained had a dry matter content of 99.2% by weight and an apparent density of 293 g/l. 90%
solubility in water at 20-C was achieved after 40 seconds. The whiteness of the dried product reaches a value of 77.6 at a wavelength of 460 nm. A bleaching agent was then added to the slurry described above. The operating parameters for drying with superheated steam are identical with those mentioned above. The following product qualities were obtained by addition of various quantities of sodium hypochlorite as bleaching agent:

Composition NaOCl Apparent Solubil- White-based density ity (90%) ness on DM (460 nm (%) (g/l) mins./s without W) 80% Sulfopon T55 0 293 -/40 77.6 20% Soda 80% Sulfopon T55 0.5 226 -/41 80.1 20% Soda 80% Sulfopon T55 1 230 -/37 80.3 20% Soda "Sulfopon T55" is a commercial name used by applicants for an anionic surfactant based on fatty alcohol sulfate.
For comparison, a commercial laundry detergent (applicants' nPersil TASn) has a whiteness of 79.7 at a wavelength of 460 nm. Covering the entire wavelength range by support with W light is irrelevant in the case of the anionic surfactant powders mentioned above because no optical brighteners are used.

Ex~mple 2 The procedure was as described in Example 1. A
slurry containing 24.1% solids was dried in the super-heated steam phase. The solid components of the start-ing mixture were the sodium salt of a Cl6~l8 fatty alcohol sulfate ("Sulfopon T55") mentioned in Example 1, the disodium salt of a Cl6~l8 alpha-sulfofatty acid and sodium carbonate in a mixing ratio of 4:1:1. The dried powder had an apparent density of 220 g/l and a solubility (90%) of 20 seconds.
The disodium salt of the C16l1B alpha-sulfofatty acid is a pale brownish paste having the following characteristic data:

Washing-active substances (Epton): 26.3 %
Unsulfonated fatty acid: 2.09%
Degree of sulfonation: 89.6%
NaCl content: 2.2%
Na2S0~ content: 3.1 %
The following Table shows the product properties of the superheated-steam-dried powders with different additions of bleach to the starting slurry:

2l4~Q~

T~bls 2: Test results Composition NaOCl Apparent Solubil- White-based density ity (90%) ness on DM (460 nm;;
(%) (g/l) mins./s without UV) Sulfopon T55 0 220 -/20 48.6 + soda + disalt (4:1:1) Sulfopon T55 1 249 -/35 64.9 + soda + disalt (4:1:1) Sulfopon T55 2 248 -/32 67.1 + soda + disalt (4:1:1) Sulfopon T55 4 253 -/16 76.0 + soda + disalt (4:1:1) EY~mple 3 The slurry of the anionic surfactant based on fatty alcohol sulfate with added soda mentioned in Example 1 has a tallow-like musty odor which is regarded as unpleasant. Emission of the odor intensifies, particularly when the paste is heated. After drying with superheated steam as described in Example 1, the powder-form product is odorless. After the fine par-ticles have been fixed by any form of granulation, there is no irritation of the mucous membrane.

2I~72~7 EY~mple 4 In its paste-like initial state, the surfactant mixture of Example 2 (sodium salt of a Cl6~l8 fatty alcohol sulfate and disodium salt of a Cl6/l~ alpha-sulfofatty acid) has a tallow-like musty odor which is;
regarded as being highly obtrusive and unpleasant, above all in the relatively warm state (T -40 C) and in the event of prolonged storage. The product dried with superheated steam is a storable powder of neutral odor which is accepted without reservation.

Claims (14)

1. A process for improving the purity and, in particular, the color and odor quality of useful materi-als and mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products (starting material), which may even be present in the form of aqueous preparations, by treatment thereof with superheated steam, optionally accompanied by drying of a water-containing starting material with superheated steam, characterized in that an impurity-containing starting material is treated with the superheated steam in finely divided form at normal pressure, bleaching agents being used to produce improvements in color.

2. A process as claimed in claim 1, characterized in that the impurity-containing starting material is treated in a spray drying zone and/or in a fluidized bed, a water-containing starting material simultaneously being freed from at least the predominant part of its water content by drying with superheated steam as the drying gas.

3. A process as claimed in claims 1 and 2, charac-terized in that an impurity-containing starting material which is capable of withstanding an at least brief increase in temperature to the evaporation temperature of the water under process conditions, particularly to temperatures in the range from about 19 to 110 C, at least largely without damage is subjected to the treat-ment.

4. A process as claimed in claims 1 to 3, charac-terized in that a starting material which is unsatisfac-tory in particular in odor and/or color and which - as an anhydrous material - is liquid and/or preferably solid at temperatures of 90 to 110° C is subjected to the process.

5. A process as claimed in claims 1 to 4, charac-terized in that a starting material containing surface-active components and/or related compounds, such as fabric softeners, is subjected to the process.

6. A process as claimed in claims 1 to 5, charac-terized in that a starting material containing anionic surfactants, nonionic surfactants, zwitterionic surfac-tant compounds and/or cationic compounds, such as fabric softeners, contaminated in particular with odoriferous components, brown-colored and/or other impurities is treated with superheated steam.

7. A process as claimed in claims 1 to 6, charac-terized in that oxidative or reducing bleaching agents, such as hydrogen peroxide, persalts, hypochlorite, or reducing agents, such as hypophosphorous acid or salts thereof, particularly alkali metal and/or alkaline earth metal salts, are added to the starting material for color correction.

8. A process as claimed in claims 1 to 7, charac-terized in that the purification treatment is carried out in conjunction with and preferably at the same time as the recovery of at least substantially dried, more particularly pourable and free-flowing useful materials and mixtures of useful materials from water-containing preparations thereof.

9. A process as claimed in claims 1 to 8, charac-terized in that the superheated steam is used at temper-atures in the range from about 100 to 450° C and prefer-ably at temperatures in the range from about 115 to 350°C under normal pressure or under only slightly increased or reduced pressures.

10. A process as claimed in claims 1 to 9, charac-terized in that flowable and sprayable aqueous solu-tions, emulsions and/or suspensions of the impurity-containing starting material are subjected to the treatment with superheated steam in finely divided form and are at least partly dried.

11. A process as claimed in claims 1 to 10, charac-terized in that bleaches are added to the starting material to be bleached in quantities of up to about 10%
by weight and preferably in quantities of from about 0.5 to 5% by weight.

12. A process as claimed in claims 1 to 11, charac-terized in that it is carried out with a superheated steam phase to which ozone has been added in very small quantities of not more than about 1 ppm, preferably below 0.5 ppm and, more particularly, in the range from about 0.05 to 0.2 ppm, based on the quantity of vapors removed from the superheated steam circuit.

13. The use of the process for drying aqueous prepa-rations of useful materials and/or mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products in a spray drying zone and/or fluidized bed using superheated steam as the drying gas for the simultaneous purification of a starting material containing in particular steam-volatile impurities.

14. The use claimed in claim 13, characterized in that the purification treatment is combined with oxida-tive or reducing bleaching simultaneously initiated in the treated material to produce light-colored useful materials or mixtures of such useful materials.