WO2011121226A1

WO2011121226A1 - Ecocompatible microemulsion and process for manufacturing such a microemulsion

Info

Publication number: WO2011121226A1
Application number: PCT/FR2011/050686
Authority: WO
Inventors: Zéphirin Mouloungui; Géraldine GIACINTI; Gérard Vilarem
Original assignee: Institut National Polytechnique De Toulouse - I.N.P. Toulouse; Institut National De La Recherche Agronomique - I.N.R.A.; Lobial
Priority date: 2010-03-29
Filing date: 2011-03-29
Publication date: 2011-10-06
Also published as: FR2957930B1; FR2957930A1

Abstract

The invention relates to a microemulsion comprising: a) at least one ester, referred to as an odd acid ester, of general formula R₁CO‑O‑R₂ (I), in which: • R₁CO- is an acyl group having a main chain comprising an odd number of carbon atoms of less than 19, • R₂ is an alkyl group comprising from 2 to 5 carbon atoms, b) at least one additional fatty substance, different from each odd acid ester (I), and chosen from the group formed: • from monounsaturated aliphatic fatty acids, • from ethyl esters of monounsaturated aliphatic fatty acids, • from glycerol monoesters of monounsaturated aliphatic fatty acids, c) at least one nonionic surfactant chosen from the group formed from alkyl polyglycosides, d) at least one compound, referred to as a multifunctional cosurfactant, of general formula R₆-CHOH-CHR₇-NR₈R₉ (II), e) and water.

Description

ECOCOMPATIBLE MICROEMULSION AND METHOD OF MANUFACTURE

FROM SUCH A MICROEMULSION

The invention relates to a microemulsion of at least one fatty substance in water, said to be ecocompatible, that is to say non-polluting and respectful of the environment and human health, and in particular whose manufacture, use, and possible dissemination in the natural environment are compatible with the constraints now imposed in terms of respect for the environment and sustainable development. The invention also relates to a method of manufacturing such a microemulsion.

Various microemulsion formulations, which can be used in particular as broad-spectrum solvents, capable of solubilising both lipophilic compounds and hydrophilic compounds, are already known. However, known microemulsions necessarily incorporate surfactants formed polluting detergents of petrochemical origin and / or whose manufacture requires the implementation of toxic reagents. In particular, it is considered until now that the use of anionic surfactants is necessary to obtain a microemulsion. In addition, some known microemulsions incorporate solvents or other compounds such as volatile organic compounds, which are themselves toxic and pollutants and / or whose manufacture requires the use of toxic and / or dangerous reagents.

No. 6,821,937 describes, for example, a microemulsion comprising an anionic detergent, a primary solvent formed of a saturated or unsaturated C ₆ -C ₂₂ carboxylic acid ester (in the examples only a mixture of C ₁₀ and C ₁₂ ). and a C ₁ -C ₄ alcohol, a short chain cosurfactant, and water. The anionic surfactant is selected from the group consisting of conventional detergents, including water-soluble salts of sulfonates, water-soluble salts of sulfates, water-soluble salts of sulfosuccinates and water-soluble salts of sulfocarboxylates. Such a microemulsion also contains a foaming anionic detergent which does not respect the environment. The invention aims to overcome the disadvantages mentioned above by proposing an eco-compatible microemulsion, which respects the environment, is non-polluting and is not dangerous for human or animal health.

The invention also aims to provide a microemulsion which is free of compound whose manufacture requires the implementation of compounds and / or polluting and / or dangerous processes.

In particular, the invention aims to provide such a microemulsion which is biodegradable and environmentally friendly throughout its life.

The invention also aims at providing a stable microemulsion adapted to act as a broad-spectrum solvent capable of solubilizing both hydrophilic compounds and lipophilic compounds.

The invention thus aims to propose such a microemulsion for its use, as a solvent, especially in the field of paints, graffiti and dirt, or as a cleaner and stain remover, and in particular for the treatment of soil removal. a solid support.

The invention also aims at providing such a microemulsion with improved stability and effectiveness compared with known microemulsion compositions.

The invention aims in particular to provide a microemulsion having improved stability at room temperature.

The invention also aims to provide such an eco-compatible microemulsion which is non-toxic to the environment, especially for living beings, for air, water and soils.

The invention also aims to provide such a microemulsion mainly comprising compounds derived from the transformation of biomass, in particular plant biomass.

In addition, the aim of the invention is to propose a microemulsion which is almost exclusively composed of natural or naturally occurring basic compounds, and by nature renewable and ecocompatible.

In particular, the invention aims to provide a microemulsion not releasing methanol during its degradation by biological means.

The invention also aims at providing such a stable microemulsion, ready for use, especially as a solvent, or capable of being diluted before use.

In addition, the invention aims to provide such a stable microemulsion having a masking power of odors, including unpleasant and nauseating odors, especially sulfur compounds or mercaptans.

The invention also aims to achieve all these objectives at lower cost, by proposing a composition of low cost, including inexpensive compounds, natural or derived from natural products, easy to obtain.

The invention also aims to provide such a microemulsion that is compatible with the constraints of manufacturing, packaging, storage, transportation and marketing, on an industrial scale.

To this end, the invention relates to a microemulsion comprising:

a) a mass proportion of between 1% and 35%, especially between 4% and 25%, in particular between 10% and 16%, of at least one ester, called odd fatty ester, of general formula (I):

FVCO-OR ₂ (I) wherein, R _f CO- is an acyl group having a main chain comprising an odd number of carbon atoms and less than 19, in particular between 3 and 17,

R ₂ is an alkyl group comprising from 2 to 5 carbon atoms, b) a mass proportion of between 0.1% and 20%, in particular between 5% and 20%, of at least one complementary fatty substance, distinct from each odd acid ester (I), and selected from the group formed:

o monounsaturated aliphatic fatty acids,

o ethyl esters of monounsaturated aliphatic fatty acids, o mono-esters of glycerol and monounsaturated aliphatic fatty acids,

c) a mass proportion of between 0.1% and 15%, especially between 1% and 15%, of at least one nonionic surfactant chosen from the group consisting of alkyl-poly-glycosides and alkenyl-poly-glycosides, d) a mass proportion of between 0.5% and 5% of at least one compound, called multifunctional cosurfactant, of general formula (II):

-CHOH-CH R ₆ R ₇ -NR ₈ R ₉ (II) wherein o R ₆ is selected from the group consisting of H, a hydroxymethyl group and an alkyl group, especially a methyl,

R ₇ is selected from the group consisting of H, the carboxyl group of formula -COOH and an alkyl group, and

R ₈ and R ₉ are chosen from the group consisting of an H, an alkyl group and a hydroxylated alkyl group,

e) and water.

In all the following:

the term "microemulsion" refers to the definition given in the "Techniques of the Engineer, Process Engineering Process", 12 157, and thus designates any monophasic system comprising a surfactant making possible coexistence, on a quasi-molecular scale , an oily phase and an aqueous phase. Such microemulsions have micro domains which are not necessarily spherical, small in size - typically in the order of 10 nm to 50 nm - and fluctuating in time and space. Such microemulsions are thermodynamically stable;

the term "main chain" of an acyl group designates any subset of atoms of said group including the function carbonyl and comprising the largest number of atoms linearly linked to each other by covalent bonds;

the value of Griffin's "Hydrophilic Lipophilic Balance" (HLB) represents the ratio multiplied by 20 of the molar mass of the hydrophilic contribution of the molecule to the total molar mass of the molecule. Thus, a compound whose hydrophilic contribution is negligible has an HLB value tending to 0, whereas a molecule with a negligible lipophilic contribution will be assigned an HLB value close to 20;

the term "alkyl group" (in English "alkyl") denotes any substituent of a compound with which it forms a covalent bond, said substituent being a hydrocarbon group of atoms derived from an alkane.

The inventors have observed, in a totally surprising manner, that an odd acid ester of general formula R 1 -CO-O-R ₂ (I), comprising an ester function formed between an acyl group of formula (R 1 CO 2), acyl group having a main chain comprising an odd number of carbon atoms of less than 19, makes it possible to form in water a stable ecocompatible microemulsion. In particular, the inventors have observed that it is possible to obtain such a stable ecocompatible microemulsion by using at least one odd acid ester (I) in a mass proportion of between 1% and 35%. The mass proportion of the odd acid ester (I) in the microemulsion is in particular chosen as a function of the number of carbon atoms of the main chain of said acyl group (RrCO-).

Advantageously and according to the invention, the number of carbon atoms of the main chain of the acyl group (RrCO-) of at least one odd acid ester (I) is chosen from 7, 9 and 11. odd acids (I) formed from an acyl group comprising between 7 and 11 carbon atoms, are preferably used in a mass proportion of between 4% and 25% to obtain a microemulsion according to the stable and transparent ecocompatible invention.

Advantageously, the number of carbon atoms of the main chain of the acyl group (R 1 -CO-) of at least one odd acid ester (I) is chosen from 15 and 17. Such an odd acid ester (1) is chosen from the group consisting of pentadecanoates of alkyl-especially ethyl pentadecanoate and alkyl heptadecanoates-especially ethyl heptadecanoate.

It is also possible to obtain such a microemulsion according to the stable ecocompatible invention with at least one odd acid ester (I) formed from an acyl group whose main chain comprises an odd number of carbon atoms and greater than 11, for example 17 carbon atoms, especially with an alkyl heptadecanoate, in particular ethyl heptadecanoate. Advantageously and according to the invention, the microemulsion comprises a mass proportion of an alkyl heptadecanoate of between 1% and 5%, in particular of the order of 1%.

In such proportions, an odd acid ester apparently forms a hydrotropic composition capable of allowing the formation in water of an eco-compatible microemulsion of high stability and which is biodegradable.

These odd acid esters are fluid, especially in the temperature range of -56 ° C to room temperature, are ecocompatible and allow the formation of microemulsions ecocompatible with the other components (b) to (e) above, which are themselves as eco-compatible, without the use of polluting and / or toxic components such as anionic detergents. In contrast, the even-acid esters (comprising an acyl group whose main chain is an even number of carbon atoms) are less fluid, especially in solid form at a temperature below 0 ° C, and do not allow the formation of a stable eco-stable microemulsion without the use of anionic detergents.

Advantageously, the odd acid ester and / or the complementary fatty substance and / or the multifunctional cosurfactant is / are "biosourced (s)", that is to say that it has (have) been obtained (s) ) each from a natural resource - especially a plant resource -. Any odd acid ester according to formula (I) may be used, alone or as a mixture in a microemulsion according to the invention. Such odium acid esters (I) having an acyl group whose main chain is an odd number of carbon atoms are for the most part commercially available products and which can also be obtained from renewable plant resources, for example by steam cracking of ricinoleic acid extracted from castor oil.

Such an odd acid ester (I) may be formed by condensation, in particular by esterification, of a fatty acid (RrCOOH) having a main chain with an odd number of carbon atoms and less than 19, and an alcohol organic (R ₂ -OH) comprising between 2 and 5 carbon atoms.

For example, the group R 1 of the fatty acid (R ₁ -COOH) may be chosen so that the fatty acid (R ₉ COOH) has a saturated main chain, which can include 3 (propanoic acid), 5 (pentanoic acid), 7 (heptanoic acid or heptyl acid), 9 (nonanoic acid or pelargonic acid), 11 (undecanoic acid or undecylic acid), 13 (tridecanoic acid), 15 (pentadecanoic acid or pentadecyl acid), or 17 (heptadecanoic acid or margaric acid ) carbon atoms.

Advantageously, the microemulsion according to the invention comprises an odd acid ester (I) in which the group Ri is formed of an aliphatic hydrocarbon chain.

Advantageously in a microemulsion according to the invention, the group of at least one odd acid ester (I) is chosen from:

n-hexyl of formula (CH ₃ - (CH ₂ ) 5-),

the n-octyl of formula (CH ₃ - (CH ₂ ) 7-),

n-deca-2-enyl of formula (CH ₂ = CH- (CH ₂ ) ₈ -),

and n-decyl of formula (CH ₃ - (CH ₂ ) ₉ -).

Such an odd acid ester of general formula (I) is obtained by esterification of a fatty acid (R _R COOH) whose main chain has an odd number of carbon atoms chosen from: heptanoic acid of formula (CH ₃ - (CH ₂ ) ₅ -COOH) (XIII),

the nonanoic acid of formula (CH ₃ - (CH ₂ ) 7 -COOH) (XIV),

undecylenic acid of formula (CH ₂ = CH- (CH ₂ ) ₈ -COOH) (XV),

undecanoic acid of formula (CH ₃ - (CH ₂ ) ₉ -COOH) (XVI).

It is possible for the main chain of the group of at least one odd acid ester (I) of a microemulsion according to the invention to contain at least one heteroatom, in particular a heteroatom chosen from the group consisting of oxygen and nitrogen. In particular, said main chain of the acyl group (RrCO-) of the odd acid ester (I) can have at least one function chosen from a hydroxyl function and an amine function. Be that as it may, the main chain of the acyl group of the odd acid ester (I) comprises an odd number of carbon atoms.

A microemulsion according to the invention may comprise, as odd acid ester (I), at least one ester formed by esterification of an α-hydroxy acid whose main chain comprises an odd number of carbon atoms, for example an alkyl lactate. Thus, in one possible embodiment, a microemulsion according to the invention may incorporate, as odd acid ester (I), an ethyl lactate of formula:

comprising an α-hydroxyl acyl group whose main chain comprises 3 carbon atoms and which is prepared from wheat starch saccharides.

Also, in a microemulsion according to the invention, the acyl group (RrCO-) of at least one odd acid ester (I) can also be chosen so as to have an unsaturated main chain. Preferably, the acyl group (R 1 CO 3) of at least one odd acid ester (I) may be chosen so as to have a monounsaturated main chain which contributes to its fluidity without, however, exhibiting toxicity.

Also, in a microemulsion according to the invention, the acyl group (R ₁ -CO-) of at least one odd acid ester (I) may be chosen so as to have a main chain having at least one branch. In particular, this odd acid ester may have such a branch consisting of a substituent chosen from methyl or ethyl. More particularly, such a branch is carried by the carbon atom at the α position of the carbonyl group of the ester function of the odd acid ester (I). Such branching contributes to the fluidity of the odd acid ester (I) but also to the chemical stability of said ester function of said odd acid ester (I).

In one possible embodiment, a microemulsion according to the invention comprises, as odd acid ester (I), at least one ester (monoester, diester or triester) of citric acid and an alcohol, in particular ethanol, said ester having an acyl group whose main chain has 5 carbon atoms, in particular ethyl citrate of formula:

As a variant or in combination, the branched acyl group of at least one odd acid ester (I) is of the iso series. In particular, at least one odd acid ester (I) is chosen from:

an ester, especially the ethyl ester, of isobutyric acid of formula:

and comprising a main chain with 3 carbon atoms, and;

an ester, especially the ethyl ester, of isopalmitic acid (or methyl-14-pentadecanoic acid) of formula:

(CH ₃ ) ₂ CH- (CH ₂ ) ₁₂ -COOH (VI) and comprising a main chain of 15 carbon atoms, and; an ester, especially the ethyl ester, of isostearic acid (or methyl-16-heptadecanoic acid) of formula:

(CH ₃ ) ₂ CH- (CH ₂ ) ₁₄ -COOH (VII) and comprising a main chain with 17 carbon atoms.

In one possible embodiment, the acyl group of at least one odd acid ester (I) is of the anteiso series.

An odd acid ester (I) of a microemulsion according to the invention also comprises a substituent R ₂ derived from an alcohol (R ₂ -OH) and comprising between 2 and 5 carbon atoms. Said alcohol (R ₂ -OH) is preferably an alcohol of vegetable origin, that is to say an alcohol obtained by transformation of the biomass, in particular by biological transformation of the biomass. Advantageously, it is ethanol obtained by alcoholic fermentation of a carbohydrate resource of vegetable origin. The use of ethanol makes it possible not only to enhance the value of said plant resource for the production of non-toxic ethylic acid esters, instead of the methyl esters requiring esterification with methanol, which is toxic. However, nothing prevents the use of a group R ₂ comprising a number of carbon atoms greater than 2.

Advantageously and according to the invention, the group R ₂ of at least one odd acid ester (I) is an ethyl ((CH ₃ -CH ₂ ) -). Such an odd acid ester (I) is obtained by esterification of a fatty acid having an odd number of carbon atom main chain with ethanol which is derived from the alcoholic fermentation of a natural carbohydrate substrate.

Advantageously and according to the invention, the group R ₂ of at least one odd acid ester (I) is chosen from the group consisting of R radicals of alcohols of general formula (Rn-OH) obtained by alcoholic fermentation from minus a carbohydrate substrate, in particular constitutive alcohols of the fusel oil. The constituent alcohols of the fusel oil are additional compounds produced during the ethanolic fermentation of at least one carbohydrate substrate, in particular apple, molasses, muscatel grapes, sweet potatoes and beet.

Advantageously and according to the invention, the group R ₂ of at least one odd acid ester (I) is chosen from the group formed:

a propyl of formula (CH ₃ -CH ₂ -CH ₂ -) (XVII),

an isobutyl of formula ((CH ₃ ) ₂ CH-CH ₂ -) (XVIII),

a pentyl of formula (CH ₃ -CH ₂ -CH ₂ -CH ₂ -CH ₂ -) (XIX),

and an iso-amyl group of formula ((CH ₃ ) ₂ CH-CH ₂ -CH ₂ -) (XX).

Thus, at least one odd acid ester (I) is formed of an acyl group of formula (R 1 CO 2) whose main chain comprises an odd number of carbon atoms and a group (R ₂ -0 -) whose main chain also includes an odd number of carbon atoms. However, it is also possible for the group R ₂ of at least one odd acid ester (I) to be an iso-amyl group of formula ((CH ₃ ) ₂ CH-CH ₂ -CH ₂ -) (XX) whose main chain comprises an even number of carbon atoms.

Advantageously and according to the invention, at least one odd acid ester (I) is ethyl n-heptanoate, of formula (CH ₃ - (CH ₂ ) ₅ -CO-O-CH ₂ -CH ₃ ) ( XXI). In particular, a microemulsion according to the invention advantageously comprises ethyl n-heptanoate in a mass proportion of between 4% and 25%.

A microemulsion according to the invention further comprises at least one complementary fatty substance comprising an even or odd number of carbon atoms.

Advantageously, a microemulsion according to the invention comprises at least one complementary fatty substance of general formula:

R ₃ -CO-O-R ₄ (VIII)

in which,

R ₃ is a monounsaturated aliphatic hydrocarbon group, comprising an even or odd number of carbon atoms,

R ₄ is selected from the group consisting of hydrogen and an alkyl group, especially an ethyl. Advantageously, the mass proportion of complementary fatty substance (s) in the microemulsion is between 0.1% and 20%, especially between 5% and 20%. The proportion of complementary fatty substance (s) in the microemulsion is chosen, in particular, as a function of the number of carbon atoms of each aliphatic hydrocarbon group R ₃ .

Advantageously, a microemulsion according to the invention comprises at least one complementary fatty substance comprising between 6 and 24 carbon atoms. Preferably, the number of carbon atoms of each complementary fatty substance is even. A fatty substance complementary to a microemulsion according to the invention may comprise an odd number of carbon atoms, but is then different in nature from each odd acid ester according to formula (I). In particular, a microemulsion according to the invention comprises, as complementary fatty substance, at least one monounsaturated fatty acid with 18 carbon atoms (Ci8: i), in particular at least one fatty acid of vegetable origin, in particular oleic acid. More particularly, a microemulsion according to the invention comprises a mass proportion of oleic acid of between 5% and 20%.

Advantageously and according to the invention, the complementary fatty substance is of plant origin.

As a variant or in combination, a microemulsion according to the invention comprises at least one complementary fatty substance of vegetable origin formed of a mono-unsaturated fatty acid ester. Advantageously and according to the invention, at least one complementary fatty substance is an ethyl ester of a fatty acid of plant origin, in particular an ethyl ester of vegetable oleic acid.

As complementary fatty substance, a stable eco-compatible microemulsion according to the invention contains at least one constituent of liquid waxes of vegetable origin and extracted from Jojoba (Simmondsia chinensis). In particular, such a microemulsion according to the invention contains at least one additional fatty substance extracted from Jojoba and chosen from a fatty acid in ⁽ ¾ _: ι, _n -9 _> a fatty acid in C20: i, n-9 _> an acid C22 fatty acid: i, _n -9 _> a C24 _: i fatty acid, _n -9 _> a C20: i fatty alcohol, _n -9 _> a C22: i fatty alcohol, _n -9 _> a fatty alcohol C24 _: i, _n -9 _> a wax formed from an ester of fatty acid _C2o: i, _n -9 ^and fatty alcohol C20: i, _n-9> a formed wax ester of the fatty acid C22: i , n-9 ^and C20: i, n-9 fatty alcohol and a wax consisting of a C20: i, n-9 fatty acid ester ^{and a} fatty alcohol thereof.

¾2: 1, ^η -9 ·

A microemulsion according to the invention also comprises at least one nonionic surfactant, in particular chosen from the group consisting of amphiphilic heterosides comprising a fraction which is osidic and polar in nature and a non-osidic fraction which is lipophilic in nature, in particular formed from a group alkyl or an alkenyl group. By alkenyl group (in English "alkenyl"), denotes any unsaturated hydrocarbon group, that is to say derived from an alkyl group (in English "alkyl") and with at least one nonaromatic unsaturation.

Advantageously, such a microemulsion according to the invention comprises at least one nonionic surfactant chosen from the group consisting of alkyl-poly-glucosides and alkenyl-poly-glucosides, and in which,

the polyglucoside group is a chain of glucose units, comprising between 1 and 10 glucose units,

the alkyl and alkenyl groups have a main chain comprising a number of carbon atoms of between 4 and 20, and optionally at least one unsaturation, and form a covalent bond of glycoside type with the anomeric carbon of at least one glucose.

Advantageously, a microemulsion according to the invention comprises, as nonionic surfactant, at least one butyl-1-glucoside in which the butyl radical forms a bond with the anomeric carbon of glucose and in which the degree of polymerization of glucose is the order of 1.2.

Advantageously, a microemulsion according to the invention comprises the composition of Simulsol SL4 ^® (Seppic, Castres, France) as a nonionic surfactant.

Advantageously and according to the invention, the mass proportion nonionic surfactant is between 1% and 15%, especially between 1% and 10%.

Advantageously and according to the invention, a microemulsion according to the invention comprises at least one nonionic surfactant whose HLB value is greater than 10, in particular between 15 and 20, in particular substantially of the order of 16.

In addition, a microemulsion according to the invention is devoid of poly-ethoxylated compounds which require, for their synthesis, to use toxic reagents. Advantageously, a microemulsion according to the invention comprises a mass proportion of between 0.5% and 5% of at least one multifunctional cosurfactant, according to the general formula (II) comprising a vicamino alcohol in which a hydroxyl function and a nitrogen atom are carried by two vicinal carbons. The inventors have observed that such a multifunctional cosurfactant of formula (II) forms with each complementary fatty substance, a supramolecular complex adapted to form a stable microemulsion.

Advantageously, a microemulsion according to the invention comprises at least one multifunctional cosurfactant (II) selected from the group consisting of N- (monoalkanol) -1-amino-2-hydroxy-alkanes and N, N- (dialkanol) -l- amino-2-hydroxy-alkanes.

In particular, at least one multifunctional cosurfactant (II) is selected from the group consisting of monoethanolamine (1-amino-2-hydroxyethane) of formula (X):

HO

\

H "C- CH

\ ²

NH ₂

(X)

serine of formula (XI)

(XI) threonine of formula (XII)

and 2,3-dihydroxypropylamine of formula (XXII)

^0H (XXII).

The inventors assume that the complexing properties of the multifunctional cosurfactant (II) with respect to the complementary fatty substance and the odd acid esters (I) thus allow the formation of a perfectly clear and stable colloidal suspension.

Advantageously, such a microemulsion according to the invention consists only of at least one odd acid ester (I), at least one complementary fatty substance, at least one nonionic surfactant, at least one alcohol cotensioactif, at least one cotensioactive multifunctional (II) and water, the proportion is then between 30% and 75%.

Such a microemulsion according to the invention is formed from nontoxic reagents, biodegradable and almost exclusively from the recovery of plant biomass.

Advantageously and according to the invention, the complementary fatty substance is of plant origin in that it comes directly, in particular by extraction, from a natural plant resource, or that it comes from a natural plant resource, especially an oil plant, by an ecocompatible treatment of chemical modification of said plant resource.

Advantageously and according to the invention, such a microemulsion is free of anionic surfactant. In contrast to the state of the art which teaches that a stable microemulsion of a fatty substance in water contains necessarily an ionic surfactant, the inventors have found that it is in fact possible to obtain such a microemulsion according to the stable ecocompatible invention, free of ionic surfactant.

In particular, a microemulsion according to the invention is free of anionic surfactants, in particular surfactants chosen from the group consisting of alkyl-sulphates, alkyl-phosphates, alkyl-phosphonates and their mixtures of low biodegradability.

A microemulsion according to the invention may comprise a single odd acid ester (I), the mass proportion of which is then between 1% and 35%. It is also possible that a microemulsion according to the invention comprises several odd acid esters (I), the sum of the masses of which represents between 1% and 35% in the mass of the microemulsion.

A microemulsion according to the invention may comprise a single complementary fatty substance whose mass proportion is then between 0.1% and 20%. However, it is also possible that a microemulsion according to the invention comprises several complementary fatty substances whose sum of the masses represents between 0.1% and 20% of the mass of the microemulsion.

A microemulsion according to the invention further comprises, as a cosurfactant alcohol, at least one alcohol of general formula R ₅ -OH (IX), in which R ₅ is a linear or branched aliphatic hydrocarbon group comprising between 2 and 6 atoms of carbon. The proportion by weight of the cosurfactant alcohol in the microemulsion is between 0.1% and 50%, in particular between 5% and 7.5%.

Advantageously and according to the invention, the microemulsion comprises a mass proportion of between 0.1% and 50% of at least one alcohol, called co-surfactant alcohol, selected from the group consisting of ethanol and propanol, isopropanol, butan-1-ol, isobutanol, amyl alcohol, isoamyl alcohol, hexan-1-ol, propylene glycol, glycerol, furfuryl alcohol , tetra-hydro furfuryl alcohol.

In a microemulsion according to the invention, the proportion of cosurfactant alcohol as a function of the cosurfactant alcohol so that the microemulsion formed is stable and ecocompatible. In general, the mass proportion of the cosurfactant alcohol is between 1% and 15%.

In particular, when the cosurfactant alcohol is butan-1-ol, its proportion in the microemulsion is advantageously between 5% and 7.5%, in particular of the order of 7%. In particular, when the cosurfactant alcohol is ethanol, its proportion in the microemulsion is advantageously between 10% and 50%.

Advantageously, the cosurfactant alcohol is "biobased", that is to say that it has each been obtained from a natural resource - particularly a plant resource -.

A microemulsion according to the invention may comprise a single nonionic surfactant whose mass proportion is then between 0.1% and 15%, especially between 1% and 15%, preferably between 0.1% and 10%. However, it is also possible that a microemulsion according to the invention comprises several nonionic surfactants whose sum of the masses represents between 0.1% and 10% of the mass of the microemulsion.

A microemulsion according to the invention may comprise a single co-surfactant alcohol whose mass proportion is then between 0.1% and 50%. However, it is also possible that a microemulsion according to the invention comprises several cotensioactive alcohols whose sum of the masses represents between 0.1% and 50% of the mass of the microemulsion.

A microemulsion according to the invention may comprise a single multifunctional cosurfactant (II) whose mass proportion is then between 0.5% and 5%. However, it is also possible that a microemulsion according to the invention comprises several multifunctional cosurfactants whose sum of the masses represents between 0.5% and 5% of the mass of the microemulsion.

In a preferred embodiment, a microemulsion according to the invention comprises:

- n-ethyl heptanoate (XXI), in a mass proportion of 14%, - oleic acid, in a mass proportion of 7%,

butan-1-ol, in a mass proportion of 7.5%,

1-amino-2-hydroxy-ethane (X), in a mass proportion of 1.5%,

butyl-1-glucoside with a degree of polymerization substantially equal to 1.2, in a mass proportion of 10% and 60% of water.

Such a microemulsion consists of compounds having an aerobic and anaerobic biodegradability increased and compatible with the constraints of sustainable development.

The invention also extends to a method for manufacturing a microemulsion according to the invention in which:

at room temperature and at atmospheric pressure, an amount of at least one complementary fatty substance, in particular a fatty substance of plant origin, and an amount of at least one multifunctional cosurfactant of general formula (II) are mixed, and then adds to this mixture, an amount of at least one odd acid ester of general formula (I), so as to form a first composition, said lipid composition, homogeneous then,

a quantity of at least one co-surfactant alcohol and water is mixed at room temperature and at atmospheric pressure, so as to obtain a second composition, called an aqueous, homogeneous and translucent composition, then,

said lipid composition is added to the aqueous composition while maintaining the lipid composition with stirring so as to cause an immediate dispersion of the lipid composition in the aqueous composition and this stirring is maintained subsequently to the addition of the lipid composition, so as to obtain a translucent colloidal solution.

In particular, the inventors have observed that the addition of a multifunctional cosurfactant (II), for example mono-ethanolamine (1-amino-2-hydroxyethane), to a lipid composition formed of a complementary fatty substance, especially a monounsaturated fatty acid, and an acid ester odd (I) formed by esterification of a fatty acid with an odd number of carbon atoms makes it possible to produce a preliminary molecular complex of the complementary fatty substance and the odd acid ester (I) in the lipid phase, said organization preliminary being adapted to then allow the formation of a microemulsion having improved stability.

Thus, in such a process, the lipid composition comprising at least one odd acid ester (I), at least one complementary fatty substance and at least one multifunctional cosurfactant (II) is prepared by simply mixing at room temperature and at atmospheric pressure. . On the other hand, the aqueous composition comprising at least one nonionic surfactant and water is prepared. The lipid composition is added gradually, at room temperature and at atmospheric pressure, progressively to the aqueous composition, taking care to form a colloidal solution. Thus this microemulsion is produced without external energy supply, especially without heating.

Fractional addition of the lipid composition is preferably carried out in the aqueous composition so that each lipid composition fraction added to the aqueous composition does not cause the volume of said aqueous composition to increase by more than 5%. However, it is also possible to add the lipid composition continuously in the aqueous composition, but the flow rate of the lipid composition added to the aqueous composition must be of the order of magnitude of the average flow rate considered for fractional addition.

Such a process for obtaining a microemulsion according to the invention is therefore non-polluting. Without energy input, including heating energy, it avoids any vaporization of the constituent components of said microemulsion and thus preserves the environment.

Advantageously and according to the invention, at least one alcohol of general formula R ₅ -OH (IX), in which R ₅ is a linear or branched aliphatic hydrocarbon group comprising between 2 and 6 carbon atoms. The proportion The bulk of the cosurfactant alcohol in the microemulsion is between 0.1% and 50%.

Advantageously and according to the invention, there is added to the aqueous composition a mass proportion of between 0.1% and 50% of at least one alcohol, called co-surfactant alcohol, selected from the group consisting of ethanol, propanol and propanol. -ol, isopropanol, butan-1-ol, isobutanol, amyl alcohol, isoamyl alcohol, hexan-1-ol, propylene glycol, glycerin, furfuryl alcohol, tetrahydro furfuryl alcohol.

In a microemulsion according to the invention, the proportion of cosurfactant alcohol is adjusted according to the cosurfactant alcohol so that the microemulsion formed is stable and ecocompatible. In general, the mass proportion of the cosurfactant alcohol is between 1% and 15%.

The invention also relates to a microemulsion and a process for obtaining such a microemulsion characterized in combination by all or some of the characteristics mentioned above or below.

Other objects, features and advantages of the invention will appear on reading the examples and the following description given solely by way of nonlimiting example and which refers to the appended figures in which:

FIG. 1 represents a block diagram of a preferred embodiment of a method according to the invention,

FIG. 2 illustrates a particular embodiment of a step of a method according to the invention.

In a process for manufacturing a microemulsion shown in FIG. 1, an amount of from about 20.degree. less a multifunctional cosurfactant 3 in a composition, said complementary body composition 2 fat, comprising at least one complementary body 2 fat. In a homogenization step 1, a homogeneous mixture 4 of the multifunctional cosurfactant (s) 3 and of the complementary fatty substance (s) 2 is thus formed. A quantity of at least one odd acid ester is then added, still with stirring, so as to form, by homogenization 6, a clear lipid phase 7.

In addition, a solution comprising at least one cosensitic alcohol 8, at least one nonionic surfactant 9 and water 10 is prepared to form an aqueous preparation 11 which is homogenized in a step 12 by magnetic stirring. A uniform and translucent aqueous phase 13 is obtained. The aqueous phase is kept under stirring, in particular with magnetic stirring capable of forming a vortex in the aqueous phase, and is added in successive stages in the vortex 14 of said aqueous phase, that is to say so to substantially maintain the clarity of said aqueous phase, the lipid phase 7. Stirring is maintained until a preparation is obtained which is a perfectly transparent microemulsion.

EXAMPLE 1 Manufacture of an Eco-compatible Microemulsion Comprising 24% Ethyl Heptanoate (Weight / Weight)

7 g of oleic acid and 1.5 g of monoethanolamine are placed

(1-amino-2-hydroxy-ethane) in a 150 mL beaker at room temperature and atmospheric pressure. A solution is obtained by mixing with magnetic stirring, to which 24 g of ethyl n-heptanoate are added to form, by mixing, a clear and homogeneous lipid composition.

In parallel, is prepared in a second beaker of 150 mL, an aqueous composition comprising 50 ml of water, 7.5 g of butan-l-ol and 10 g of Simulsol SL4 ^® (Seppic, Castres, France) that is homogenized by magnetic stirring.

The lipid composition is then gradually added in small amounts to the aqueous composition while maintaining the composition. aqueous solution with vigorous magnetic stirring, adapted to form a vortex, in the aqueous composition. An eco-compatible microemulsion according to the invention is thus obtained of the type "microemulsion of oil in water", which is perfectly stable over time and which is biodegradable. The average size of the micro-domains of the microemulsion according to the invention, measured by electron microscopy is of the order of ten nanometers. The inventors have thus observed that the oleic acid complementary fatty substance and the multifunctional cotensioactive agent (II) formed from 1-amino-2-hydroxyethane (monoethanolamine) form a homogeneous mixture promoting the dispersion of ethyl n-heptanoate. (XXI) in the aqueous composition.

The inventors have further observed that the use of an ethyl n-heptanoate composition (XXI) comprising of the order of 7% by weight of saturated heptanoic acid (C _{7: 0} ) in place of oleic acid, does not allow the formation of a stable microemulsion. In addition, the use of palmitic acid (Cis _: o) saturated, instead of oleic acid, also does not allow the formation of a stable microemulsion.

EXAMPLE 2 Manufacture of an Eco-compatible Microemulsion Comprising 14.7% Ethyl Heptanoate and 40.0% Ethanol (Weight / Weight)

According to the manufacturing method described in Example 1, a stable and ecocompatible microemulsion is formed from 4.3 g of oleic acid, 0.9 g of monoethanolamine (1-amino-2-hydroxyethane) and 14.7 g of ethyl n-heptanoate. An aqueous composition comprising 38.6 ml of water, 40.0 g of 99% ethanol and 1.5 g of Simulsol SL4 ^® (Seppic, Castres, France).

EXAMPLE 3 Manufacture of an Eco-compatible Microemulsion Comprising 16.6% Ethyl Heptanoate and 38.3% Ethanol (Weight / Weight)

According to the manufacturing method described in Example 1, a stable and ecocompatible microemulsion is formed from 4.7 g of oleic acid, 1.0 g of monoethanolamine (1-amino-2-hydroxy-ethane) and 16.6 g of ethyl n-heptanoate. An aqueous composition comprising 33.3 ml of water, 38.3 g of 99% ethanol and 6.7g of Simulsol SL4 ^® (Seppic, Castres, France).

EXAMPLE 4 Production of an Eco-compatible Microemulsion Comprising 11.3% of Ethyl Undecanoate (Weight / Weight)

According to the manufacturing method described in Example 1, a stable and ecocompatible microemulsion is formed from 16.5 g of oleic acid, 3.5 g of monoethanolamine (1-amino-2-hydroxy-ethane) and 11.3 g of ethyl undecanoate. An aqueous composition comprising 47 ml of water, 12.2 g of 99% ethanol and 9.5 g of Simulsol SL4 ^® (Seppic, Castres, France).

EXAMPLE 5 Production of an Eco-compatible Microemulsion Comprising 11.3% of Ethyl Undecylenate (Weight / Weight)

According to a manufacturing method described in Example 1, a stable and ecocompatible microemulsion is formed from 16.5 g of oleic acid, 3.5 g of monoethanolamine (1-amino-2-hydroxyethane) and 11.3 g of ethyl undecylenate. An aqueous composition comprising 47 ml of water, 12.2 g of 99% ethanol and 9.5 g of Simulsol SL4 ^® (Seppic, Castres, France).

EXAMPLE 6 Visual Evaluation of the Relative Anti-fouling Performance of Microemulsions According to the Invention

The performance of a treatment microemulsion according to the invention is visually evaluated by comparing the anti-fouling results obtained for a microemulsion according to the invention tested with those obtained, under the same conditions, by an EMD8 tanning composition (AMI, Cormery, France). ) reference. According to the Schaeffe scale, a comparative note, called Schaeffe's Note (NS), between -5 and +5, is attributed to the result of the cleaning obtained with the microemulsion according to the invention tested in comparison with the result obtained with the reference dewatering composition. A positive score reflects a result of the microemulsion according to the tested invention which is better than the result obtained with the reference composition, while a negative score reflects a worse result of the microemulsion according to the invention than the result obtained with the reference composition. The average score of five judges, men and women experienced in the field of visual evaluation, is calculated for a product tested on a solid support, as well as the standard deviation of these results.

EXAMPLE 7 Colorimetric Evaluation of the Anti-fouling Performance of Microemulsions According to the Invention

The chromatic coordinates L * a * b * (L * for the brightness constant, a * for the red / green balance and b * for the yellow / blue balance) are measured for the light reflected by each of the treated surfaces before and after anti-fouling treatment using a Chroma Meter tristimulus colorimeter, Minolta CR-310. The difference in color measured between the soiled surface and the cleaned surface is evaluated according to the formula: Δ £ = _Α / ( _Δ ^ ² ) + ( _ΔΩ * ² ) + ( _Δ¾ * ² ),

wherein a high value of ΔΕ indicates effective cleaning of the support, and or a low value of ΔΕ indicates ineffective carrier cleaning. The relative performance (PR) of the test composition is then evaluated with reference to the reference composition according to the formula:

PR (composition tested) ^-

tested) ^~

A positive value of PR indicates that the microemulsion according to the invention tested is more effective than the reference composition, and a negative value of PR indicates that the microemulsion according to the invention tested is less effective than the reference composition.

EXAMPLE 8 Application of the soil on the solid surface

The performance tests of the treatment microemulsions according to the invention and of the reference composition are carried out on seven different types of supports with a homogeneous and delimited solid surface, namely on brick, on concrete, on Trespa brand boards. ^® (Neuilly-sur-Seine, France), on laminate, on 3M adhesive, particularly on colored road sign coatings, on aluminum sheet and on low density polyethylene (LDPE).

The anti-fouling performance tests of the microemulsion treatment according to the invention and the reference to four distinct types of graffiti, namely the indelible marker, the paint, the acrylic glue and the bituminous tar, are carried out. As an indelible marker graffiti, a Sharpie brand blue ink marker is used on Trespa ^® type surfaces and a Pentel ^® brand black ink marker is used for other types of surfaces. As a "paint" type graffiti, a white aerosol paint of the Auto-K brand (Auto-K, France) is used on the surfaces of the Trespa ^® panels type, and a black aerosol paint of Belton brand for the other types of surfaces. As a soiling type "acrylic glue" is used an acrylic adhesive for carpets and floors plastic brand Casto ^® . As tar-like soiling, a Spado ^® brand bituminous tar is used.

Prior to the application of soiling, the solid surfaces are washed with alcohol, then wiped so as to leave no stains or traces on the solid surfaces.

The "indelible marker" type graffiti are produced by successive application of two layers of indelible marker each produced by juxtaposition of two series of lines, the lines of each of the two series being made in two substantially perpendicular directions.

The soiling type "paint" are performed by successive application by aerosol of two layers of paint each made by juxtaposition of two sets of traces, the traces of each of the two series being made in two substantially perpendicular directions.

The so-called "acrylic glue" and "tar bituminous" type stains are produced by brush or brush application of a single homogeneous layer of glue made by juxtaposing glue lines. For all types of soiling on all types of solid surface, a drying period at room temperature of a duration substantially of the order of 24 hours is observed after the application of soiling.

EXAMPLE 9: Treatment of the solid surface

A quantity of a treatment composition is applied to the brush on each soiled surface at the rate of 1.5 g +/- 0.2 g of composition per 100 cm ² of surface to be cleaned. The composition is allowed to act for a period of 5 minutes, then the solid surface is scrubbed according to a procedure described in Table 1 below:

Table 1 above expresses the number of scouring passes that are manually performed on an area of a solid support for the removal of various soils by means, unless otherwise specified, of a 20 cm x cotton cloth. 20 cm folded to form 8 superimposed layers,

⁽¹⁾ a 20 cm x 6 cm natural fiber brush is used for the scrubbing treatment,

⁽²⁾ for the scrubbing treatment, a folded cotton cloth is used to form 32 superimposed layers,

⁽⁾ Two series of 50 scouring passes are made by means of a cotton cloth of dimension 20 cm x 20 cm,

⁽⁴⁾ four series of 50 scouring passages are carried out using a cotton cloth of size 20 cm × 20 cm,

⁽⁵⁾ four sets of 50 scouring passes were made with a 20 cm x 20 cm cotton cloth, folding the cloth between the four sets of

50 passages, then 4 passages with a dry cloth,

⁽⁶⁾ Four passes are made, then four passes after changing the cloth, then four sets of 4 scouring passages by means of a 20 cm x 20 cm cotton cloth, folding the cloth between the four sets of cloths. 4 passage, ⁽⁷⁾ four sets of 4 scouring passes were made with a cotton cloth of size 20 cm x 20 cm, folding the cloth between the four sets of 4 passages and 4 passages with a dry cloth ,

⁽⁸⁾ for this material, a passage represents 10 successive passages applied according to the diagram shown in FIG.

At the end of this treatment, the results obtained are analyzed according to the two visual and colorimetric approaches.

Microemulsion treatment according to the invention and reference composition.

Three microemulsions of treatment according to the invention are prepared as described in Examples 3, 4 and 5, comprising:

for the first time, ethyl heptanoate in a mass proportion of 16.6%, as a single odd acid ester.

for the second, ethyl undecanoate in a weight ratio of 11.3%, as a single odd acid ester,

- For the third, ethyl undecylenate in a mass proportion of 11.3%, as a single odd acid ester.

The reference tinting composition (EMD8, AMI, Cormery, France) comprises isopropyl alcohol and an ethoxylated fatty alcohol. It should be noted that such a composition is toxic to the environment because of the reagents necessarily used for its synthesis. The average NS value represents the average of the scores obtained by a composition for the treatment of the type of soiling on the various substrates tested.

EXAMPLE 10: Soil treatment by application of the microemulsion according to the invention based on ethyl heptanoate according to Example 3.

The results of the microemulsion soil removal tests according to the invention are given in Table 2 below, in comparison with results obtained with the prior reference EMD8 debonding composition.

nd = not determined

It is observed in Table 2 above that a microemulsion according to the invention comprising ethyl heptanoate has improved anti-fouling performance compared with a treatment with the reference templating composition, in particular with respect to paints ( _mean NS = + 2.46 +/- 1.22), glue (NS _average = + 1, 40 +/- 0.95). In addition, the treatment according to the invention with the composition comprising heptanoate has a performance improved vis-à-vis the tar, especially on the concrete support.

EXAMPLE 11: Soil treatment by application of the microemulsion according to the invention based on ethyl undecanoate according to Example 4.

The results of the soil-killing tests by a treatment microemulsion according to the invention are given in Table 3 below by comparison with results obtained with the AMD 8 standard taring composition.

nd = not determined

It is observed in Table 3 above that a treatment microemulsion according to the invention comprising ethyl undecanoate has improved anti-fouling performance compared with a treatment with the standard EMD8 evaporation composition. marker, especially on the concrete support.

EXAMPLE 12: Soil treatment by application of the microemulsion according to the invention based on ethyl undecylenate according to Example 5.

The results of the soil removal tests are shown in Table 4 below by comparison with results obtained with the EMD8 standard tapping composition.

nd = not determined

It is observed in Table 4 above that a treatment microemulsion according to the invention comprising ethyl undecylenate has improved anti-fouling performance compared with the treatment with the reference tinting composition with respect to the marker. and glue, in particular on the concrete support, and vis-à-vis the paint including a support type adhesive support.

Claims

1 / Microemulsion comprising:

a) a mass proportion of between 1% and 35% of at least one ester, called odd acid ester, of general formula (I):

FVCO-O-Rg (I) wherein, o RrCO- is an acyl group having a main chain comprising an odd and a lower carbon number of 19, o R ₂ is an alkyl group comprising from 2 to 5 carbon atoms carbon, b) a mass proportion of between 0.1% and 20% of at least one complementary fatty substance, distinct from each odd acid ester (I), and chosen from the group formed:

o monounsaturated aliphatic fatty acids,

c) a mass proportion of between 0.1% and 10% of at least one nonionic surfactant selected from the group consisting of alkyl-polyglycosides and alkenyl-poly-glycosides,

d) a mass proportion of between 0.5% and 5% of at least one compound, called multifunctional cosurfactant, of general formula (II):

Wherein R ₆ is selected from the group consisting of an H, a hydroxymethyl group and an alkyl group, wherein R ₆ -CHOH-CH R ₇ -NR ₈ R ₉ (II)

e) and water.

Microemulsion according to Claim 1, characterized in that the number of carbon atoms in the main chain of the acyl group (R ₁ -CO-) of the odd acid ester (I) is selected from 7, 9 and 11.

3 / microemulsion according to one of claims 1 and 2, characterized in that the group R 1 of the odd acid ester (I) is chosen from:

n-hexyl of formula CH ₃ - (CH ₂ ) 5-,

the n-octyl of formula CH ₃ - (CH ₂ ) 7-,

n-deca-2-enyl of formula CH ₂ = CH- (CH ₂ ) ₈ -,

and n-decyl of formula CH ₃ - (CH ₂ ) ₉ -.

4 / microemulsion according to one of claims 1 to 3, characterized in that the R ₂ group of the odd acid ester (I) is an ethyl (CH ₃ -CH ₂ -).

5 / microemulsion according to one of claims 1 to 3, characterized in that the group R ₂ of the odd acid ester (I) is selected from the group consisting of Ru radicals of alcohols of general formula Ru -OH, in particular constituent alcohols of the fusel oil obtained by alcoholic fermentation of at least one carbohydrate substrate.

6 / microemulsion according to one of claims 1 to 3 or 5, characterized in that the group R ₂ of the odd acid ester (I) is chosen from the group formed:

a propyl of formula (CH ₃ -CH ₂ -CH ₂ -) (XVII),

an isobutyl of formula ((CH ₃ ) ₂ CH-CH ₂ -) (XVIII), - a pentyl of formula (CH ₃ -CH ₂ -CH ₂ -CH ₂ -CH ₂ -) (XIX) and an iso-amyl group of formula ((CH ₃ ) ₂ CH-CH ₂ -CH ₂ -) (XX).

Microemulsion according to one of claims 1 to 6, characterized in that the odd acid ester (I) is ethyl n-heptanoate of formula (CH ₃ - (CH ₂ ) ₅ -CO-O- CH ₂ -CH ₃ ) (XXI).

8 / microemulsion according to one of claims 1 to 7, characterized in that the mass proportion of the odd acid ester (I) is between 4% and 25%.

Microemulsion according to one of Claims 1 to 8, characterized in that the complementary fatty substance is of plant origin.

10 / microemulsion according to one of claims 1 to 9, characterized in that the mass proportion of the complementary fat is between 5% and 20%.

11 / microemulsion according to one of claims 1 to 10, characterized in that the mass proportion of the cosurfactant alcohol is between 5% and 7.5%.

12 / microemulsion according to one of claims 1 to 11, characterized in that it comprises a mass proportion of between 0.1% and 50% of at least one alcohol, said cotensioactive alcohol, selected from the group consisting of ethanol, propan-1-ol, isopropanol, butan-1-ol, isobutanol, amyl alcohol, isoamyl alcohol, hexan-1-ol, propylene glycol, glycerol, furfuryl alcohol, tetrahydro furfuryl alcohol.

13 / microemulsion according to one of claims 1 to 12, characterized in that the mass proportion of the nonionic surfactant is between 1% and 15%.

14 / microemulsion according to one of claims 1 to 13, characterized in that the value of the HLB of the nonionic surfactant is greater than 10, in particular between 15 and 20, in particular of the order of 16.

15 / microemulsion according to one of claims 1 to 14, characterized in that it is free of anionic surfactant.

16 / Microemulsion according to one of claims 1 to 15, characterized in that it comprises:

n-ethyl heptanoate (XXI), in a mass proportion of 14%, of oleic acid, in a mass proportion of 7%,

butan-1-ol, in a mass proportion of 7.5%,

2% of ramino-2-ethanol-1, in a mass proportion of 1.5%, butyl glucoside degree of polymerization substantially equal to 1.2, in a mass proportion of 10%,

- and water. 17 / A method of manufacturing a stable microemulsion according to one of claims 1 to 16, characterized in that:

a quantity of at least one additional fatty substance and an amount of at least one multifunctional cosurfactant of general formula (II) are mixed at ambient temperature and at atmospheric pressure, and then a quantity of at least less an odd acid ester of general formula (I), so as to form a first composition, called lipid composition, homogeneous then,

at room temperature and at atmospheric pressure, an amount of at least one cosurfactant alcohol and water is mixed so as to obtain a second composition, called an aqueous, homogeneous and translucent composition, and then

said lipid composition is added to the aqueous composition while maintaining the lipid composition with stirring so as to cause an immediate dispersion of the lipid composition in the aqueous composition, and this stirring is maintained subsequently to the addition of the lipid composition, so as to obtain a translucent colloidal solution.

18 / A method according to claim 17, characterized in that is added to the aqueous composition an amount of at least one nonionic surfactant.