Process for the production of light-colored, low-viscosity surfactant concentrates

Light-colored, low-viscosity surfactant concentrates, are made by mixing: mixing: (a) a sugar surfactant selected from the group consisting of an alkyl and/or alkenyl oligoglycoside, a fatty acid-N-alkyl polyhydroxyalkylamide and a combination thereof and, (b) a betaine in a ratio by weight of (a) to (b) of from about 90:10 to about 10:90, with the proviso that components (a) and (b)are present in the gel phase.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a process for the production of light-colored, 
low-viscosity surfactant concentrates by mixing sugar surfactants and 
betaines in the gel phase. 
2. Description of the Related Art 
Alkyl oligoglycosides, more particularly alkyl oligoglucosides, are 
nonionic surfactants which are acquiring increasing significance by virtue 
of their excellent detergent properties and their high ecotoxicological 
compatibility. The production and use of these substances have been 
described just recently in a number of synoptic articles of which those by 
H. Hensen in Skin Care Forum, (October 1992), D. Balzer and N. Ripke in 
Seifen-Ole-Fette-Wachse 118, 894 (1992) and B. Brancq in 
Seifen-Ole-Fette-Wachse 118, 905 (1992) are cited as representative. 
Equally favorable properties are known to be exhibited by a second group 
of sugar surfactants, namely fatty acid-N-alkyl polyhydroxyalkylamides, 
more particularly fatty acid-N-alkyl glucamides. 
In some respects, however, the use of sugar surfactants is attended by 
problems. For example, it is not possible to produce pumpable aqueous 
concentrates with a solids content above 40% by weight without the sugar 
component undergoing partial decomposition in the course of the 
concentration process. In addition, the glycosides and glucamides share 
this property with most anionic surfactants which form a viscous gel phase 
above an active substance content of around 35% by weight. In addition, 
sugar surfactants have a tendency to crystallize during storage at low 
temperatures which is a significant obstacle to their subsequent use. 
The use of sugar surfactants of the types mentioned above together with 
amphoteric or zwitterionic surfactants of the betaine type in 
surface-active formulations is known in principle from the prior art. 
Mixtures of--albeit short-chain--alkyl glucosides and alkyl amidobetaines 
or imidazolinium betaines were disclosed for the first time in an article 
by G. Proserpio et al in Rivista Italiana 56, 567 (1974). EP-A 0 075 994 
(Procter & Gamble) describes combinations of alkyl glucosides with amine 
oxides, unsaturated soaps, water-soluble builders and selected anionic 
surfactants. In addition, the mixtures may contain amphoteric surfactants, 
for example betaines of the 
6-(N-dodecylbenzyl-N,N-dimethylammonium)-hexanoate type. U.S. Pat. No. 
4,668,422 (Henkel Corp.) discloses liquid soaps and foam baths containing 
alkyl glucosides, betaines and amine oxides. EP-A-0 250 181 (Helene 
Curtis) relates to liquid detergents containing alkyl glucosides, anionic 
surfactants and selected amphoteric surfactants of betaine structure. 
Surfactant combinations containing alkyl glucosides, alkyl sulfates, 
betaines and/or amine oxides and optionally alkanolamides are disclosed in 
EP-A 0 341 071 (Unilever). Manual dishwashing detergents containing alkyl 
glucosides, fatty alcohol sulfates, fatty alcohol ether sulfates and 
betaines are known from EP-A 0 513 138, DE-A1 42 34 487 and DE-A1 43 11 
114 (all Henkel). Mild shampoos based on alkyl glucosides, anionic 
surfactants and betaines are described in EP-A 0 453 238 (Unilever). 
Finally, EP-A 0 508 507 (Berol Nobel) relates to liquid detergents 
containing alkyl glucosides, anionic surfactants and selected amphoteric 
surfactants of betaine structure. However, all these publications are 
concerned with dilute water-containing surfactant mixtures or formulations 
and not with concentrates. 
The use of fatty acid-N-alkyl polyhydroxyalkylamides is also the subject of 
a number of publications. For example, their use as thickeners is known 
from European patent application EP-A1 0 285 768 (Huls). FR-A 1 580 491 
(Henkel) describes water-containing detergent mixtures based on sulfates 
and/or sulfonates, nonionic surfactants and optionally soaps which contain 
fatty acid-N-alkyl glucamides as foam regulators. Mixtures of short-chain 
and relatively long-chain glucamides are described in DE-C1 44 00 632 
(Henkel). In addition, DE-A1 42 36 958 and DE-A1 43 09 567 (Henkel) report 
on the use of glucamides containing relatively long alkyl chains as 
pseudoceramides in skin-care formulations and on combinations of 
glucamides with protein hydrolyzates and cationic surfactants in hair-care 
products. 
International patent application WO 92/06153; WO 92/06156; WO 92/06157; WO 
92/06158; WO 92/06159 and WO 92/06160 (Procter & Gamble) relate to 
mixtures of fatty acid-N-alkyl glucamides with anionic surfactants, 
sulfate and/or sulfonate surfactants, ether carboxylic acids, ether 
sulfates, methyl ester sulfonates and nonionic surfactants. The use of 
these substances in various laundry detergents, dishwashing detergents and 
cleaning formulations is described in international patent applications, 
WO 92/06152; WO 92/06154; WO 92/06155; WO 92/06161; WO 92/06162, WO 
92/06164, WO 92/06170, WO 92/06171 and WO 92/06172 (Procter & Gamble). 
There is a need on the market for concentrated surfactant mixtures based on 
alkyl and/or alkenyl oligoglucosides which are flowable and pumpable 
despite a solids content of more than 30% by weight and preferably of the 
order of 50 to 60% by weight and which have a significantly reduced 
tendency to crystallize, i.e. improved stability in storage. Since 
surfactant compounds of the type in question are mainly used in manual 
dishwashing detergents and hair shampoos, skin-cosmetic or rather 
dermatological compatibility is also extremely important. 
Surfactant concentrates are a particularly favorable commercial formulation 
for manufacturers and users because they have been minimized in terms of 
their water content and hence incur lower transport and storage costs. 
Nevertheless, it is desirable that the surfactant concentrates should have 
a sufficiently high viscosity in the final formulations, which are of 
course heavily diluted and have a solids content of 20 to 30% by weight, 
and should readily lend themselves to thickening using known additives. 
Accordingly, the complex problem addressed by the present invention was to 
provide light-colored, pumpable water-containing surfactant concentrates 
with high dermatological compatibility based on alkyl glycosides or fatty 
acid glucamides and betaines which would be distinguished by high 
stability in storage and which would have a Brookfield viscosity of at 
most 10,000 mPa.multidot.s and a solids content of 40 to 60% by weight. 
DESCRIPTION OF THE INVENTION 
The present invention relates to a process for the production of 
light-colored, low-viscosity surfactant concentrates in which 
(a1) alkyl and/or alkenyl oligoglycosides and/or 
(a2) fatty acid-N-alkyl polyhydroxyalkylamides and 
(b) betaine surfactants 
are mixed in a ratio by weight of (a) to (b) of 90:10 to 10:90, with the 
proviso that the starting materials are present in the gel phase. 
It has surprisingly been found that it is not necessary for the production 
of the required concentrates to start out from low-viscosity, i.e. dilute, 
water-containing starting materials and to concentrate them in a 
subsequent step. On the contrary, it has been found that the mixing of 
concentrated starting materials which are present in the gel phase and 
which, therefore, are not themselves low in viscosity results in the 
formation of products which are low in viscosity, light-colored and stable 
in storage. 
Alkyl and/or alkenyl oligoglycosides 
Alkyl and alkenyl oligoglycosides are known nonionic surfactants 
corresponding to formula (I): 
EQU R.sup.1 O-G!.sub.p (I) 
in which R.sup.1 is an alkyl and/or alkenyl radical containing 4 to 22 
carbon atoms, G is a sugar unit containing 5 or 6 carbon atoms and p is a 
number of 1 to 10. They may be obtained by the relevant methods of 
preparative organic chemistry. EP-A1 0 301 298 and WO 90/03977 are cited 
as representative of the extensive literature available on the subject. 
The alkyl and/or alkenyl oligoglycosides may be derived from aldoses or 
ketoses containing 5 or 6 carbon atoms, preferably glucose. Accordingly, 
the preferred alkyl and/or alkenyl oligoglycosides are alkyl and/or 
alkenyl oligoglucosides. 
The index p in general formula (I) indicates the degree of oligomerization 
(DP degree), i.e. the distribution of mono- and oligoglycosides, and is a 
number of 1 to 10. Whereas p in a given compound must always be an integer 
and, above all, may assume a value of 1 to 6, the value p for a certain 
alkyl oligoglycoside is an analytically determined calculated quantity 
which is generally a broken number. Alkyl and/or alkenyl oligoglycosides 
having an average degree of oligomerization p of 1.1 to 3.0 are preferably 
used. Alkyl and/or alkenyl oligoglycosides having a degree of 
oligomerization of less than 1.7 and, more particularly, between 1.2 and 
1.4 are preferred from the applicational point of view. 
The alkyl or alkenyl radical R.sup.1 may be derived from primary alcohols 
containing 4 to 11 and preferably 8 to 10 carbon atoms. Typical examples 
are butanol, caproic alcohol, caprylic alcohol, capric alcohol and undecyl 
alcohol and the technical mixtures thereof obtained, for example, in the 
hydrogenation of technical fatty acid methyl esters or in the 
hydrogenation of aldehydes from Roelen's oxosynthesis. Alkyl 
oligoglucosides having a chain length of C.sub.8 to C.sub.10 (DP=1 to 3), 
which are obtained as first runnings in the separation of technical 
C.sub.8-18 coconut oil fatty alcohol by distillation and which may contain 
less than 6% by weight of C.sub.12 alcohol as an impurity, and also alkyl 
oligoglucosides based on technical C.sub.9/11 oxoalcohols (DP=1 to 3) are 
preferred. In addition, the alkyl or alkenyl radical R.sup.1 may also be 
derived from primary alcohols containing 12 to 22 and preferably 12 to 14 
carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol, cetyl 
alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl 
alcohol, elaidyl alcohol, petroselinyl alcohol, arachyl alcohol, gadoleyl 
alcohol, behenyl alcohol, erucyl alcohol, brassidyl alcohol and technical 
mixtures thereof which may be obtained as described above. Alkyl 
oligoglucosides based on hydrogenated C.sub.12/14 coconut oil fatty 
alcohol having a DP of 1 to 3 are preferred. 
Fatty acid-N-alkyl polyhydroxyalkylamides 
Fatty acid-N-alkyl polyhydroxyalkylamides are nonionic surfactants which 
correspond to formula (II): 
##STR1## 
in which R.sup.2 CO is an aliphatic acyl radical containing 6 to 22 carbon 
atoms, R.sup.3 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 12 carbon atoms and 3 to 10 hydroxyl groups. 
Fatty acid-N-alkyl polyhydroxyalkylamides are known compounds which may 
normally be 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. Processes 
for their production are described in U.S. Pat. No. 1,985,424, in U.S. 
Pat. No. 2,016,962 and in U.S. Pat. No. 2,703,798 and in international 
patent application WO 92/06984. An overview of this subject by H. 
Kelkenberg can be found in Tens. Surf. Det. 25, 8 (1988). 
The fatty acid-N-alkyl polyhydroxyalkylamides are preferably derived from 
reducing sugars containing 5 or 6 carbon atoms, more particularly from 
glucose. Accordingly, the preferred fatty acid-N-alkyl 
polyhydroxyalkylamides are fatty acid-N-alkyl glucamides which correspond 
to formula (III): 
##STR2## 
Preferred fatty acid-N-alkyl polyhydroxyalkylamides are glucamides 
corresponding to formula (III) in which R.sup.3 is hydrogen or an alkyl 
group and R.sup.2 CO represents the acyl component 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 reductive amination of glucose 
with methylamine and subsequent acylation with lauric acid or C.sub.12/14 
coconut oil fatty acid or a corresponding derivative are particularly 
preferred. In addition, the polyhydroxyalkylamides may also be derived 
from maltose and palatinose. 
Betaine surfactants 
Betaines are known surfactants which are largely produced by 
carboxyalkylation, preferably carboxymethylation, of aminic compounds. The 
starting materials are preferably condensed with halocarboxylic acids or 
salts thereof, more particularly sodium chloroacetate, 1 mole of salt 
being formed per mole of betaine. The addition of unsaturated carboxylic 
acids, such as acrylic acid for example, is also possible. Information on 
nomenclature and, in particular, on the difference between betaines and 
"true" amphoteric surfactants can be found in the article by U. Ploog in 
Seifen-Ole-Fette-Wachse, 198, (1982) 373. Further overviews on this 
subject have been published, for example, by A. O'Lennick et al. in HAPPI, 
November (1986) 70, by S. Holzman et al. in Tens. Det. 23, (1986) 309, by 
R. Bilbo et al. in Soap Cosm. Chem. Spec. April (1990) 46 and by P. Ellis 
et al. in Euro Cosm. 1, (1994) 14. 
Examples of suitable betaines are the carboxyalkylation products of 
secondary and, in particular, tertiary amines corresponding to formula 
(IV): 
##STR3## 
in which R.sup.4 represents alkyl and/or alkenyl radicals containing 6 to 
22 carbon atoms, R.sup.5 represents hydrogen or alkyl radicals containing 
1 to 4 carbon atoms, R.sup.6 represents alkyl radicals containing 1 to 4 
carbon atoms, n is a number of 1 to 6 and X is an alkali metal and/or 
alkaline earth metal or ammonium. 
Typical examples are the carboxymethylation products of hexyl methylamine, 
hexyl dimethylamine, octyl dimethylamine, decyl dimethylamine, dodecyl 
methylamine, dodecyl dimethylamine, dodecyl ethyl methylamine, C.sub.12/14 
cocoalkyl dimethylamine, myristyl dimethylamine, cetyl dimethylamine, 
stearyl dimethylamine, stearyl ethyl methylamine, oleyl dimethylamine, 
C.sub.16/18 tallow alkyl dimethylamine and technical mixtures thereof. 
Carboxyalkylation products of amidoamines corresponding to formula (V): 
##STR4## 
in which R.sup.7 CO is an aliphatic acyl radical containing 6 to 22 carbon 
atoms and 0 or 1 to 3 double bonds, m is a number of 1 to 3 and R.sup.5, 
R.sup.6, n and X are as defined above, may also be used. 
Typical examples are reaction products of fatty acids containing 6 to 22 
carbon atoms, namely 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, elaeostearic acid, arachic acid, gadoleic acid, behenic 
acid and erucic acid and technical mixtures thereof, with 
N,N-dimethylaminoethylamine, N,N-dimethylaminopropylamine, 
N,N-diethylaminoethylamine and N,N-diethylaminopropylamine which are 
condensed with sodium chloroacetate. It is preferred to use a condensation 
product of C.sub.8/18 coconut oil fatty acid N,N-dimethylaminopropylamide 
with sodium chloroacetate. 
Other suitable starting materials for the betaines to be used in accordance 
with the invention are imidazolines corresponding to formula (VI): 
##STR5## 
in which R.sup.8 is an alkyl radical containing 5 to 21 carbon atoms, 
R.sup.9 is a hydroxyl group, an OCOR.sup.8 or NHCOR.sup.8 group and m=2 or 
3. These compounds are also known compounds which may be obtained, for 
example, by cyclizing condensation of 1 or 2 moles of fatty acid with 
polyfunctional amines, such as for example aminoethyl ethanolamine (AEEA) 
or diethylenetriamine. The corresponding carboxyalkylation products are 
mixtures of different open-chain betaines. 
Typical examples are condensation products of the above-mentioned fatty 
acids with AEEA, preferably imidazolines based on lauric acid 
or--again--C.sub.12/14 coconut oil fatty acid, which are subsequently 
betainized with sodium chloroacetate. 
Surfactant concentrates 
The surfactant concentrates are produced from highly concentrated 
water-containing starting materials present in gel form. This means that 
the alkyl and/or alkenyl oligoglycosides and/or the fatty acid-N-alkyl 
polyhydroxyalkylamides are used in the form of aqueous gels with a sugar 
surfactant content of 45 to 60% by weight and preferably 45 to 55% by 
weight. The betaine surfactants are generally used with a non-aqueous 
component of 45 to 60% by weight and preferably 48 to 54% by weight and 
with a betaine component of 25 to 40% by weight and preferably 28 to 35% 
by weight. The surfactant concentrates are produced purely mechanically by 
mixing the gel-form starting materials, optionally at elevated 
temperatures and with intensive shearing. 
In one preferred embodiment of the invention, the betaines are reacted in 
known manner, for example by reaction of suitable tertiary amines with 
aqueous sodium chloroacetate solution at around 90.degree. C., and the 
water-containing glucoside or glucamide pastes are added to the crude 
betaines without cooling. The betainization is carried out with just that 
quantity of water as solvent which ensures the required solids content in 
the mixed product containing the sugar surfactants. In overall terms, this 
means that the betainization may be carried out with an unusually small 
quantity of solvent. 
Flow promoters 
Polyols may be added to the concentrates in small quantities to improve 
their flowability. Examples of suitable polyols are: 
glycerol; 
alkylene glycols, for example ethylene glycol, diethylene glycol, propylene 
glycol; 
technical oligoglycerol mixtures with a degree of autocondensation of 1.5 
to 10, such as for example technical diglycerol mixtures with a diglycerol 
content of 40 to 50% by weight; 
methylol compounds, such as in particular trimethylol ethane, trimethylol 
propane, trimethylol butane, pentaerythritol and dipentaerythritol; 
hydroxycarboxylic acids, for example glycolic acid, tartaric acid and 
citric acid; 
lower alkyl glucosides, more particularly those containing 1 to 8 carbon 
atoms in the alkyl radical, such as for example methyl and butyl 
glucoside; 
sugar alcohols containing 5 to 12 carbon atoms, for example sorbitol or 
mannitol; 
sugars containing 5 to 12 carbon atoms, for example glucose or sucrose; 
aminosugars, for example glucamine. 
Polyols--more particularly glycerol--are added to the concentrates in 
quantities of preferably 0.5 to 5% by weight and, more preferably, 1 to 3% 
by weight, based on the concentrates. 
The surfactant concentrates may contain small quantities, i.e. 0.5 to 3% by 
weight and preferably 1 to 2% by weight, based on the concentrates, of 
free fatty acids as additional flow promoters. Typical examples of such 
flow promoters are caproic acid, caprylic acid, 2-ethylhexanoic acid, 
capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic 
acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic 
acid, petroselic acid, linoleic acid, linolenic acid, elaeostearic acid, 
arachic acid, gadoleic acid, behenic acid and erucic acid and the 
technical mixtures thereof obtained, for example, in the pressure 
hydrolysis of natural fats and oils, in the reduction of aldehydes from 
Roelen's oxosynthesis or in the dimerization of unsaturated fatty acids. 
Commercial Applications 
The surfactant concentrates according to the invention are distinguished by 
a low viscosity and yield point. They are light-colored, color-stable and 
stable in storage. Accordingly, they are suitable for the production of a 
number of surface-active formulations, for example laundry detergents, 
dishwashing detergents and cleaning formulations, in which they may be 
present in quantities of 0.5 to 50% by weight and preferably in quantities 
of 2 to 35% by weight, based on the particular formulation.