USE OF A CRYSTALLISATION-INHIBITING ADDITIVE FOR SURFACE-ACTIVE NONIONIC GLYCOSIDES

Abstract: Addition of an anionic derivative of a glycoside of formula (I): R(A)s(G)n wherein R is an aliphatic hydrocarbon group having 6-20, preferably 8-16 carbon atoms, G is a saccharide residue, A is an oxyalkylene having 2-4 carbon atoms or 3-oxy-2-hydroxy-propylene, n is a number from 1 to 10, preferably a number from 1 to 4, and s is a number from 0 to 5; or a nonionic alkylene oxide adduct of a glycoside of formula (I), wherein the alkylene oxide contains 2-4 carbon atoms, inhibits or prevents crystallisation of an aqueous concentrate of a glycoside of formula (I). The addition of the derivative or the adduct also yields relatively small changes of the properties of the glycoside mixture.

Description: USE OF A CRYSTALLISATION-INHIBITING ADDITIVE FOR SURFACE- ACTIVE NONIONIC GLYCOSIDES The present invention relates to a concentrated surface-active glycoside composition, which contains an anion- ic derivative of an alkyl glycoside or a nonionic alkylene oxide adduct of an alkyl glycoside as a crystallisation- inhibiting additive. It is well-known that concentrated solutions of alkyl polyglycosides have an undesired tendency to precipitate crystals when stored for a long time. The alkyl glycosides, such as -alkyl glycosides, have a steric appearance, which makes them easily form crystals with crystal water. Since the formation of crystals is disadvantageous in many respects, it is important to reduce the crystallisation as much as possible. From WO 94/03569 it is known that the crystallisation of alkyl or alkylene oligoglycosides can be reduced by adding alkyl glycosides on the basis of short-chain alcohols, oligoglycosides acetalised with guerbet alcohols or polyols, short-chain primary alcohols, fatty alcohol polyglycol ethers, polyethylene glycol, glucose or Fe- (III) -ions . WO 95/04592 suggests the addition of a surface-active amphoteric compound to an alkyl polyglycoside having an alkyl chain of at least 10 carbon atoms for preventing crystallisation, whereas DE 40 33 928 discloses the use of a partially esterified glyceride for the same purpose. Even if the crystallisation-inhibiting additives, which are described in the above-mentioned patent publications, reduce the crystallisation, the effect is in many cases insufficient, especially after a long time of storing. Besides, the additives may change the properties of the glycosides in an undesirable manner. For example, the frothing of the alkyl glycosides may be affected. According to the present invention, it is therefore desired that the crystallisation-reducing additives, besides having a high crystallisation-inhibiting capacity, should also be active in relative small amounts and, in these amounts, have little effect on the properties of the glycosides. According to the present invention, it has now surprisingly been found that a) an anionic derivative of a glycoside of the formula R(A),(G) n (I) wherein R is an aliphatic hydrocarbon group having 6-20, preferably 8-16 carbon atoms, G is a saccharide residue, A is an oxyalkylene having 2-4 carbon atoms or 3-oxy-2-hydroxypropy- lene, n is a number from 1 to 10, preferably a number from 1 to 4, and s is a number from 0 to 5; or b) a nonionic alkylene oxide adduct of a glycoside of formula I, wherein the alkylene oxide contains 2-4 carbon atoms and has an excellent crystallisation-inhibiting effect on an aqueous concentrate of a glycoside of formula I. Owing to the fact that the crystallisation-inhibiting additive is based on a glycoside of the same fundamental structure, it has been found that the changes of the properties of the glycoside, that are caused by the additive, can be reduced to a considerable extent. The group G is suitably a monosaccharide residue, such as pentose or hexose. Specific examples are glucose, mannose, galactose, talose, allose, altrose, idose, arabinose, xylose, ribose and lyxose. For commercial reasons, glucose is preferred. The group R can be a straight or branched, saturated or unsaturated aliphatic group. Examples of suitable aliphatic groups R are obtained by reaction with coconut alcohols, n-hexyl alcohol, n-octanol, n-decyl alcohol, n- dodecyl alcohol, n-tetradecyl alcohol, n-hexadecyl alcohol, ; n- octadecyl alcohol, undecyl alcohol, tridecyl alcohol, oxo and guerbet alcohols, such as 2-ethylhexanol, 2-propylheptanol, 2- butyloctanol and methyl-substituted alcohols containing 2-5 groups of the formula -CH(CH 3 )- in the carbon chain. According to a preferred embodiment, the group R in the additive and the hydrophobic group in the surface-active glycoside are equal. The anionic derivatives are preferably carboxylates, but also sulphonates, phosphates, phosphonates and sulphates can be used. The number of anionic groups is usually 1 or 2. The nonionic, crystallisation-inhibiting alkylene oxide adduct is suitably an adduct, which is obtained by adding 1- 10, preferably 2-6 alkyleneoxy units per mole of alkyl glycoside. By selecting different alkylene oxides or combinations thereof, the frothing can easily be adapted to a glycoside of formula I. For instance, adducts with propylene or butylene oxide, or a combination of ethylene oxide and of higher alkylene oxide in the end position result in lower frothing than an adduct with only ethylene oxide. The additives can be added in amounts of about 0.1-20% by weight, based on the weight of the surface-active alkyl glycoside, which usually is 10-80% of the concentrate. Preferred anionic derivatives are those exhibiting the general formula (ii) wherein R, A, G, s and n are as above, r is a number 0 or 1, the sum of all r being at least 1, preferably 1-2, Y is a group (OR 1 ) p (X) m , wherein Rj . is an aliphatic hydrocarbon group having 1-8, preferably 1-4 carbon atoms, m is a number 1-2, X is a carboxyl-containing group, p is 0 or 1, and m is 1, m 1 is the total charge of the anion and M is a preferably monovalent cation, such as a sodium ion, and z is the charge of the cation. Compounds of formula II can be prepared in the manner stated in WO 88/01640 and DE 40 15 655. Preferred nonionic ethylene oxide adducts are those having the formula (Q) r I R(A) β (G) n (HI) wherein R, A, G, s, n and r are as above and Q is the group (B) V H, wherein B is an alkyleneoxy group and v is a number from 1 to 12, preferably 2 to 6. Compounds of formula III can suitably be prepared in a prior-art manner by alkoxilating a compound of formula I . The present invention also relates to a concentrate containing a) 10-80, preferably 45-70% by weight of an alkyl glycoside of formula I, b) 0.1-20, preferably 0.5-15% by weight, based on the alkyl glycoside, of an anionic derivate of a glycoside or a nonionic alkylene oxide adduct of a glycoside according to the invention, and c) 4-90%, preferably 15-55% by weight of water. If the crystallisation-inhibiting additive is an anionic derivative, the concentrate suitably contains 0.1-8, preferably 0.5-5% by weight, based on the alkyl glycoside, whereas when the crystallisation-inhibiting additive is a nonionic alkylene oxide adduct, the content suitably is 2-20, preferably 3-15% by weight, based on the alkyl glycoside. The concentrate may also contain solubilising agents, for instance propylene glycol, for improving the solubility, especially at low temperatures. The present invention is further illustrated by the following Example. Example Aqueous concentrates designated 1-6 and formulated according to the invention and designated A-D as comparative compositions were prepared by mixing in water the components stated in Table 1. Table 1 10 15 20 The formulations according to 1-6 and A-D where then allowed to stand from 2 to 6 months at 20°C and 6°C and any crystallisations were noted. The formulations were also tested in respect of frothing (Ross-Miles, after 0 min and 5 in at a concentration of 0.05% by weight at 20°C) and surface tension at a concentration of 0.1% by weight at 20 °C. The following results were obtained. Table 2 As appears from the results, the formulations B-D had either a considerably increased degree of frothing (B and C) or a lower reduction of the surface tension (D) . The formulations 1-6 according to the invention have approximately the same degree of frothing and surface tension as the formulation A, which has no addition of a crystallisation-inhibiting compound.

Claims: CLAIMS 1. Use of an anionic derivative of a glycoside of the formula R(A) s (G) n (I) wherein R is an aliphatic hydrocarbon group having 6-20, preferably 8-16 carbon atoms, G is a saccharide residue, A is an oxyalkylene having 2-4 carbon atoms or 3-oxy-2-hydroxy- propylene, n is a number from 1 to 10, preferably a number from 1 to 4 , and s is a number from 0 to 5 ; or a nonionic alkylene oxide adduct of a glycoside of formula I, wherein the alkylene oxide contains 2-4 carbon atoms, for inhibiting or preventing crystallisation of an aqueous concentrate of a glycoside of formula I. 2. Use as claimed in claim 1, wherein the anionic derivative is a carboxylate, sulphonate, phosphate, phos- phonate or sulphate, and the nonionic alkylene oxide adduct is obtained by adding 1-10, preferably 2-6 alkyleneoxy units per mole of alkyl glycoside. 3. Use as claimed in any one of claims 1-2 , wherein the anionic derivative and/or the nonionic alkylene oxide adduct is used in an amount of 0.1-20% by weight, based on the weight of the alkyl glycoside. 4. Use as claimed in any one of claims 1-3, wherein the anionic derivative is of the general formula (II) wherein R, A, G, s and n are as above, r is a number 0 or 1 , the sum of all r being at least 1, preferably 1-2, Y is a group (OR 1 ) p (X) m , wherein Rj. is an aliphatic hydrocarbon group having 1-8, preferably 1-4 carbon atoms, is a number 1-2, X is a carboxyl-containing group, p is 0 or 1, and m is 1, mi is the total charge of the anion and M is a preferably monovalent cation, and z is the charge of the cation. 5. Use as claimed in any one of claims 1-4, characterised in that the ethylene oxide adduct is of formula ( Q) r I R(A) s (G) n (HI) wherein R, A, G, s, n and r are as above and Q is the group (B) V H, wherein B is an alkyleneoxy group and v is a number from 1 to 12, preferably 2 to 6. 6. Use as claimed in any one of claims 1-5, wherein R in the glycoside and the anionic derivative or the nonionic alkylene oxide adduct are equal. 7. A concentrate of an alkyl glycoside, characterised in that it contains a) 10-80, preferably 45-70% by weight of an alkyl glycoside of formula I according to claim 1, b) 0.1-20, preferably 0.5-15% by weight, based on the alkyl glycoside, of an anionic derivate of a glycoside or a nonionic alkylene oxide adduct of a glycoside as defined in claim 1, 2, 4, 5 or 6, and c) 4-90%, preferably 15-55% by weight of water. 8. A concentrate as claimed in claim 7 , characterised in that the crystallisation-inhibiting additive consists of the anionic derivative, which has a content of 0.1-8% by weight, based on the alkyl glycoside. 9. A concentrate as claimed in claim 7, characterised in that the crystallisation-inhibiting derivative consists of the nonionic alkylene oxide adduct, which has a content of 2-20% by weight, based on the alkyl glycoside. 10. A method of preventing or inhibiting the forming of crystallisation in an aqueous concentrate of an alkyl glycoside, characterised in that an anionic derivative of a glycoside of formula R(A).(G) n (I) wherein R is an aliphatic hydrocarbon group having 6-20, preferably 8-16 carbon atoms, G is a saccharide residue, A is an oxyalkylene having 2-4 carbon atoms or 3-oxy-2-hydroxy- propylene, n is a number from 1 to 10, preferably a number from 1 to 4 , and s is a number from 0 to 5 ; or a nonionic alkylene oxide adduct, wherein the alkylene oxide contains 2-4 carbon atoms, of a glycoside of formula I, is added to the concentrate in an amount of 0.1-20% by weight, based on the weight of the alkyl glycoside.

Inventors: JOHANSSON INGEGAERD, KARLSSON BO, JOHANSSON, INGEGAERD, KARLSSON, BO
Applicants: AKZO NOBEL NV, JOHANSSON INGEGAERD, KARLSSON BO, AKZO NOBEL N.V., JOHANSSON, INGEGAERD, KARLSSON, BO
Application year: 1997
Main classification: C07H15
IPC codes: B01F17, C07H15, C11D1