EP0750034A2 - Storage stable, concentrated surfactant composition based on alkylglycosides - Google Patents

Abstract

Storage-stable, conc. aq. surfactant compsn. comprises 40 - 75 wt.% alkyl glucosides of formula R<1>O-(G)p (I); 1 - 15 wt.% fatty acid; 0 - 5 wt.% alkali or alkaline earth halide as electrolyte; and 5 - 59 wt.% water. R<1> = 6-22C (pref. 12 - 18)C alkyl; G = glucoside residue; and p = 1 - 3.

Description

The invention relates to a storage-stable, concentrated surfactant composition based on alkyl glucosides with the addition of fatty acids as a stabilizing agent.

Alkyl glucosides are known substances. They correspond to the general formula

RO- [G] _p

in which R is derived from a fatty alcohol residue and G stands for the glucose residue. One or more glucose residues can be bound to a fatty alcohol residue, which results in an average degree of oligomerization p via the glucose units. In the literature, the terms alkyl polyglucoside and alkyl oligoglucoside are therefore used for this product group.

Alkyl glucosides are important non-ionic surfactants, which have found their way into detergents, dishwashing detergents and cleaning agents due to their good detergent properties and high environmental compatibility.

For this purpose it is necessary to keep alkyl glucosides available for a certain period of time, for example as aqueous solutions or pastes, until they are finished. However, since aqueous alkyl glucosides show a strong tendency to crystallize, water containing crystals form over time when stored under ambient conditions Agglomerates that greatly reduce the pumpability of the products.

These problems occur in particular in the case of alkyl glucosides in which the alkyl radical has 12 or more carbon atoms or in commercially available alkyl glucoside mixtures in which the higher-chain fraction is correspondingly high and has more than 50% alkyl radicals with 12 and more carbon atoms .

Usually, alkyl glucosides are therefore not stored at room temperature, but at temperatures of at least 35 ° C. In this way, crystallization of the preparation can largely be prevented, but storage at elevated temperature is associated with additional effort and can also severely impair the color quality of the products.

Kristallisationsmoderatoren" vorgeschlagen, wie beispielsweise Alkyloligoglykoside auf Basis kurzkettiger Alkohole, Polyethylenglykol oder Eisen-(III)-Ionen, die aber den Nachteil aufweisen, daß sie die Tensideigenschaften bzw. die Farbe beeinträchtigen.According to DE-A-42 25 224, the addition of a number of to improve the crystallization resistance

Crystallization moderators "proposed, such as alkyl oligoglycosides based on short-chain alcohols, polyethylene glycol or iron (III) ions, but which have the disadvantage that they impair the surfactant properties or the color.

The object of the invention was therefore to find a concentrated surfactant composition based on alkyl glucosides, in which the glucosides can be stored at temperatures below 35 ° C. without the pumpability of the products being impaired by the formation of crystalline agglomerates.

• a) 40 bis 75 Gew.-% Alkylglucoside der Formel
  
          R¹O-[G]_p     (I)
  
  wobei

  R¹

  einen Alkylrest mit 6 bis 22 C-Atomen, insbesondere 12 bis 18 C-Atomen, bedeutet,

  G

  der Glucosid-Rest und

  p

  eine Zahl von 1 bis 3 ist,

• b) 1 bis 15 Gew.-% Fettsäure,
• c) 0 bis 5 Gew.-% Elektrolyt aus Alkali- oder Erdalkalihalogeniden sowie
• d) 5 bis 59 Gew.-% Wasser.

The invention thus relates to a storage-stable, concentrated, aqueous surfactant composition containing

• a) 40 to 75 wt .-% alkyl glucosides of the formula
  
  R ¹ O- [G] _p (I)
  
  in which

  R ¹

  is an alkyl radical having 6 to 22 carbon atoms, in particular 12 to 18 carbon atoms,

  G

  the glucoside residue and

  p

  is a number from 1 to 3,

• b) 1 to 15% by weight of fatty acid,
• c) 0 to 5 wt .-% electrolyte from alkali or alkaline earth metal halides and
• d) 5 to 59 wt .-% water.

In a particularly preferred embodiment, at least 50% of the radicals R ^{1 have} 12 or more carbon atoms.

A preferred alkyl residue distribution in the alkyl glucoside is C ₈ <3% C ₁₀ <3% C ₁₂ 50 to 100% C ₁₄ 10 to 40% C ₁₆ 0 to 15% C ₁₈ 0 to 10%

It has now surprisingly been found that in the concentrated surfactant compositions according to the invention the tendency to crystallize of the longer-chain alkyl glucosides is reduced to such an extent that concentrated, aqueous compositions can be produced which show no tendency to crystallize even at temperatures below 35 ° C. and are stable in storage and color for months . These mixtures are therefore also common Ambient temperatures in the range of 10 to 25 ° C stable and storable.

As already stated at the beginning, alkyl glycosides are known substances which can be obtained from fatty alcohols and reducing sugars (see, for example, EP-A1-0 301 298 and WO 90/3977).

The alkyl glycosides can be derived from aldoses or ketoses with 5 or 6 carbon atoms, preferably glucose. Only the alkyl glucosides have gained technical importance.

The index number p in the general formula (I) indicates the degree of oligomerization, i.e. H. the distribution of mono- and oligoglucosides, and stands for a number between 1 and 3. While p must always be an integer in a given compound, the value p for a certain alkyl glucoside is an analytically determined arithmetic quantity, which usually represents a fractional number . Alkyl glucosides with an average degree of oligomerization p of 1.1 to 3.0 are preferably used. From an application point of view, those alkyl glucosides are preferred whose degree of oligomerization is less than 1.7 and in particular between 1.2 and 1.6.

The alkyl radical R ¹ can be derived from primary alcohols having 4 to 22, preferably 12 to 14, carbon atoms. They are typically available as technical mixtures.

Suitable fatty acids are natural or synthetic fatty acids with 8 to 18 carbon atoms, with natural fatty acid compositions such as coconut fatty acid or palm kernel fatty acid being preferred.

A higher proportion with an average chain length of 12 to 14 carbon atoms is preferred. The are preferred Fatty acids in amounts of 2.5 to 10 wt .-%, in particular 5 to 7.5 wt .-% used.

If necessary, alkali metal or alkaline earth metal halides are added to the mixture as electrolyte, sodium chloride usually being used.

As a rule, the electrolyte is added in solid form or from a concentrated aqueous solution. This can be done at any time during the preparation of the mixture, if appropriate preferably before finally adjusting the pH of the preparation.

If necessary, the pH of the preparation is finally adjusted to a pH of ≦ 8, preferably ≦ 6, by adding a mineral acid or an organic acid.

Preferred acids are phosphoric acid, hydrochloric acid, sulfuric acid, tartaric acid, citric acid and lactic acid.

The mixtures according to the invention can be prepared by simply mixing commercially available alkyl glucoside solutions and fatty acids. Mixing can take place at room temperature or, in order to achieve a lower viscosity, at a slightly elevated temperature of 30 to 80 ° C. The mixtures can of course also be prepared from solid starting materials by dissolving them in water.

The preparations according to the invention are generally resistant to microbial attack. This applies in particular at pH values of <6. Their microbiological stability can be further improved by adding alkali or alkaline earth metal halides.

The surfactant compositions according to the invention are stable on storage and show no tendency towards crystallization. They have an excellent surfactant effect and have excellent dirt-removing and skin-friendly properties. They are suitable for the production of detergents, dishwashing detergents and cleaning products, as well as hair and body care products, in which they are usually used in amounts of 3 to 30% (based on the aqueous preparation).

Depending on the intended use, conventional ingredients such as cosurfactants, builders, dyes, viscosity regulators and fragrances can be added.

Examples Comparative example (not according to the invention)

A dry alkyl glucoside, which contains about 4% by weight of water, is dissolved in water, so that a solution with 50% by weight of solids is formed. The pH of the solution is 7.

The alkyl glucoside is identified as follows (% by weight): Composition of the alkyl residues: C ₈ 10% C ₁₀ 10% C ₁₂ 58% C ₁₄ 14% C ₁₆ 6% C ₁₈ 2% Degree of oligomerization: n = 1.26

The solution is divided and stored in closed vessels at temperatures of 20 and 40 ° C. The sample stored at 20 ° C is white and solid after 14 days, while the one at 40 ° C stored sample is still liquid even after 6 months of storage. However, it has turned much darker during storage.

Example 1

A solution is prepared from the dry alkyl glucoside described in the comparative example presented above, coconut fatty acid, water and a little aqueous, concentrated sodium hydroxide solution, which is composed as follows (% by weight): Alkyl glucoside: 60% Water: 35% hardened coconut fatty acid: 5% Sodium hydroxide solution up to pH 7

The solution is divided and stored in closed vessels at temperatures of 20 and 40 ° C for 6 months. After this storage period, the samples are homogeneous and flowable; no crystal formation or precipitation can be seen in any of the samples.

Example 2

Similar to Example 1, a solution is prepared from a dry alkyl glucoside containing about 3% by weight of water, lauric acid, water, aqueous, concentrated hydrochloric acid and sodium chloride, which is composed as follows (% by weight): Alkyl glucoside: 41.8% Water: 49.0% Lauric acid: 7.2% Sodium chloride: 2.0% Hydrochloric acid up to pH 5

The alkyl glucoside is identified as follows (% by weight): Composition of the alkyl residues: C ₈ 1 % C ₁₀ 1 % C ₁₂ 68% C ₁₄ 25% C ₁₆ 5% Degree of oligomerization: n = 1.52

After storage of this solution under the same conditions as in Example 1, these solutions are also homogeneous and flowable. No crystal formation or precipitation can be seen in any of the samples.

The solution is also subjected to a microbiological load test according to DAB 10 (German Pharmacopoeia). In this test, the preparation proves to be microbiologically stable.

Claims (2)

Storage-stable, concentrated, aqueous surfactant composition containing a) 40 to 75 wt .-% alkyl glucosides of the formula

R ¹ O- [G] _p (I)

in which R ^{1 is} an alkyl radical having 6 to 22 carbon atoms, in particular 12 to 18 carbon atoms, and G the glucoside residue and p is a number from 1 to 3, b) 1 to 15% by weight of fatty acid, c) 0 to 5 wt .-% electrolyte from alkali or alkaline earth metal halides and d) 5 to 59 wt .-% water. Surfactant composition according to claim 1, characterized in that at least 50% of the radicals R ^{1 have} 12 or more carbon atoms.