COMPOSITION COMPRISING A SOLID FATTY ETHER, AN ALKALINE HYDROXIDE AND A POLYSACCHARIDE OF MICROBIAL ORIGIN

Abstract

COMPOSITION COMPRISING A SOLID FATTY ETHER, AN ALKALINE HYDROXIDE, AND A POLYSACCHARIDE OF MICROBIAL ORIGIN. The present invention relates to a composition comprising at least one solid fatty ether, at least one alkali hydroxide, and at least one polysaccharide of microbial origin. It also relates to a process for straightening keratin fibers using the composition.

Description

Title of the invention: COMPOSITION COMPRISING A SOLID FATTY ETHER, AN ALKALI HYDROXIDE AND A POLYSACCHARIDE OF MICROBIAL ORIGIN

[0001] The present invention relates to a composition comprising at least one solid fatty ether, at least one alkali hydroxide and at least one polysaccharide of microbial origin.

[0002] Many people are not satisfied with the appearance of their hair, especially people who have curly hair most often seek to achieve straight hair and, conversely, those who have straight hair wish to have curly hair.

[0003] The first of the techniques usually used to obtain permanent deformation of the hair consists, in a first step, in opening the disulfide bonds -SS- of the keratin (keratocystin) using a composition containing a suitable reducing agent (reduction step) then, after rinsing the hair thus treated, generally with water, in reconstituting in a second step said disulfide bonds by applying to the hair previously put under tension (for example by curlers), an oxidizing composition (oxidation step, also called fixing) so as to finally give the hair the desired shape.

[0004] This technique allows you to achieve either wavy hair, straightening it, uncrimping it or smoothing it.

[0005] The second technique for obtaining permanent hair deformation consists of carrying out an operation called lanthionization, using a composition containing a base belonging to the hydroxide family. It leads to replacing disulfide bonds (-CH2-SS-CH2-) with lanthionine bonds (-CH2-S-CH2-).

[0006] The compositions generally used to carry out lanthionization contain as a base an alkali hydroxide such as an alkali or alkaline earth metal hydroxide. Compared to the first technique described previously using a reducing agent, this lanthionization technique does not require a fixing step, since the formation of lanthionine bridges is irreversible. It is therefore carried out in a single step. However, it is customary to carry out a neutralizing shampoo after this type of process to lower the pH of the fiber.

[0007] The hair straightening products may be presented in the form of ready-to-use compositions or in the form of kits of at least two compositions to be mixed at the time of use, one of which comprises hydroxides in high concentration.

[0008] These two techniques allow you to create either wavy hair or straightening, uncrimping or smoothing. However, the lanthionization technique is mainly used for styling naturally frizzy hair.

[0009] These techniques used for straightening are generally implemented on curly or voluminous hair in order to obtain a more or less pronounced straightening and a reduction in the volume and apparent mass of the hair.

[0010] The aim is to obtain compositions which provide a pleasant experience, that is to say, in particular in the form of a creamy texture, which are easily distributed over the entire head of hair, which are easy to apply and which are easy to rinse without compromising on effectiveness, in particular in terms of regular straightening between the root and the tip while respecting as much as possible the integrity of the keratin fibers and giving said fibers the best possible cosmetic properties, in particular in terms of shine.

[0011] These compositions must also be stable during storage and during the pause and application time, in particular stable after 1 week and / or 1 month and / or 4 months, in particular under the effect of heat,

[0012] Furthermore, the formulation of environmentally friendly cosmetic products, i.e. those whose design and development take environmental issues into account, is becoming a major concern to help meet global challenges.

[0013] It is therefore essential to propose more sustainable compositions and / or preparation processes and / or ingredients that can thus respond to these environmental challenges, in particular by promoting the use of renewable raw materials and / or those with a good index of naturalness and / or natural origin. In addition, in order to preserve natural resources and in particular water, it is of interest to propose compositions that make it possible to reduce the quantity of water required, in particular when using the product.

[0014] The applicant discovered that it was possible to achieve the desired properties with a composition comprising at least one solid fatty ether, at least one alkali hydroxide and at least one polysaccharide of microbial origin.

[0015] Such a composition is stable over time and has a homogeneous texture which facilitates the application of the composition to the hair fibers.

[0016] The compositions according to the invention have a smooth, creamy texture, are shiny and very easy to apply. They have an opaque character allowing better localization of the product and therefore greater reliability of the result from the root to the tip or over the entire head of hair.

[0017] The compositions are also very easy to rinse, which limits water consumption.

[0018] In addition, these compositions make it possible to obtain good smoothing / straightening or on- curling / curling hair.

[0019] The compositions according to the invention have a smooth, creamy texture, are shiny and very easy to apply. They have an opaque character allowing the product to be located on the hair.

[0020] The composition of the invention is in particular intended for the treatment of keratin fibers, and in particular human keratin fibers such as hair.

[0021] The composition in accordance with the present invention makes it possible to obtain a good straightening effect on keratin fibers without degrading them and without altering their cosmetic properties.

[0022] In addition, the composition in accordance with the invention has improved stability over time, in particular during storage under the effect of heat, for example at temperatures equal to 45°C.

[0023] The present invention therefore relates in particular to a composition comprising at least one fatty ether, at least one alkali metal hydroxide and at least one polysaccharide of microbial origin.

[0024] The invention also relates to a process for treating keratin fibers, in particular a process for permanently deforming keratin fibers, preferably for straightening keratin fibers, using this composition.

[0025] Another object of the invention is the use of this composition for the treatment of keratin fibers, in particular the permanent deformation of keratin fibers, preferably the straightening of keratin fibers.

[0026] In the following, unless otherwise indicated, the limits of the indicated intervals are included in the invention.

[0027] By “at least one” is meant one or more.

[0028] By "stable" is meant a composition which does not exhibit any significant change in appearance, odor, pH, and / or rheology after storage, in particular after storage for 2 months at 4°C. Among the changes in appearance, mention may in particular be made of phase separation, precipitation, creaming. Solid fatty ether

[0029] The composition according to the invention comprises at least one solid fatty ether.

[0030] Preferably, the solid fatty ethers are of formula (I) RO-R' in which R and R', identical or different, denote a linear or branched alkyl or alkenyl radical, R and R' comprising at least 8 carbon atoms. The fatty ether useful in the present invention is a solid fatty ether.

[0031] By “solid fatty ether” is meant a fatty ether which is solid at room temperature and atmospheric pressure (25°C, 1 atm).

[0032] Preferably, the ether is chosen from the compounds for which the radicals R and R', identical or different, denote a linear or branched, C8-C40, preferably C10-C30, more preferably C14-C24.

[0033] According to a particular embodiment of the invention, the radicals R and R', which may or may not be identical, are radicals derived from oleic (Cl8), caprylic (C8), capric (ClO), lauric (C12), palmitic (C16), myristic (C14), behenic (C22), stearic (Cl8), linoleic (Cl8), linolenic (Cl8), arachidic (C20) alcohols.

[0034] Preferably, R and R' are saturated.

[0035] Preferably, R and R' represent a linear C8-C40, preferably C10-C30, more preferably C14-C24 alkyl radical.

[0036] More particularly R and R' are identical.

[0037] Preferably, R and R' are identical and represent a linear C14-C24 alkyl radical, better still R and R' denote a linear C16-C22 alkyl radical, better still deriving from stearic alcohol (Cl8).

[0038] More preferably, the ethers which can be used according to the invention have a melting point above 50°C.

[0039] The fatty ethers which can be used according to the invention can be soluble or insoluble in the compositions, but preferably they are insoluble.

[0040] These compounds can be prepared according to the process described in patent application DE 41 27 230.

[0041] According to a particular embodiment, the fatty ether is distearyl ether or diactode-cylether, and corresponds to the formula above in which R and R' represent a CH3(CH2)i7 group.

[0042] The total content of solid fatty ether(s) according to the invention can vary from 0.1 to 35% by weight relative to the total weight of the composition.

[0043] According to a preferred embodiment, the solid fatty ether(s) according to the invention are preferably present in a total content ranging from 1 to 30% by weight, preferably from 2.5 to 25% by weight, better still from 5 to 20% by weight, even better still from 7.5 to 15% by weight, relative to the weight of the composition. Alkaline hydroxide

[0044] The composition according to the invention comprises at least one alkali metal hydroxide.

[0045] By alkali hydroxide is meant a mineral, organic or hybrid hydroxide having an alkaline pH in aqueous solution, preferably a pH ranging from 7.5 to 14, preferably from 8 to 13.5, even more preferably pH 11 and 13.

[0046] The alkali hydroxide according to the invention may be chosen from hydroxides of alkali or alkaline earth metals.

[0047] By alkali or alkaline earth metal hydroxide is meant a compound of the following formula:

[0048] M(0H)x

[0049] with M being a metal chosen from alkali metals (group 1 of table pe periodic table of elements) or alkaline earth metals (group 2 of the periodic table of elements), x being a number equal to 1 or 2.

[0050] Preferably, the alkali metal hydroxide(s) are chosen from sodium hydroxide, lithium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide and mixtures thereof, more preferably from sodium hydroxide, lithium hydroxide, calcium hydroxide and mixtures thereof, more preferably chosen from sodium hydroxide, calcium hydroxide and mixtures thereof.

[0051] The alkali hydroxide according to the invention can also be chosen from guanidine hydroxide.

[0052] Preferably, the alkali metal hydroxide(s) according to the invention are chosen from alkali metal or alkaline earth metal hydroxides, preferably from sodium hydroxide, lithium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide and mixtures thereof, more preferably from sodium hydroxide, lithium hydroxide, calcium hydroxide and mixtures thereof, better still from sodium hydroxide, calcium hydroxide and mixtures thereof.

[0053] The alkali metal hydroxide(s) generally represent from 0.1 to 60% by weight, preferably from 0.5 to 55% by weight, better still from 1 to 50% by weight relative to the total weight of the composition.

[0054] Preferably, the alkali or alkaline-earth metal hydroxide(s) represent from 0.1 to 60% by weight, preferably from 0.5 to 55% by weight, better still from 1 to 50% by weight relative to the total weight of the composition.

[0055] According to a particular embodiment, the composition comprising the alkali or alkaline-earth metal hydroxide(s) may also comprise guanidine carbonate.

[0056] In this particular embodiment, the composition comprising the alkali or alkaline earth metal hydroxide(s) and the guanidine carbonate may result from the mixing of at least one composition comprising the alkali or alkaline earth metal hydroxide(s) and at least one composition comprising the guanidine carbonate. The concentration of guanidine carbonate in the composition further comprising the alkali or alkaline earth metal hydroxide(s) may vary from 0.1 to 60% by weight, preferably from 1 to 50% by weight, better still from 2 to 40% by weight relative to the total weight of the composition. Polysaccharide of microbial origin

[0057] The composition according to the invention comprises at least one polysaccharide of microbial origin.

[0058] By polysaccharide of microbial origin is meant a polysaccharide derived from mi microorganism(s), such as bacteria, yeasts, fungi, microalgae.

[0059] The polysaccharides of microbial origin are notably chosen from: - xanthan gum (polymer of glucose, mannose acetate, mannose / pyruvic acid and glucuronic acid); - gellan gum (polymer of partially acylated glucose, rhamnose and glucuronic acid); - scleroglucan gum (glucose polymer); and mixtures thereof.

[0060] Preferably, the polysaccharide(s) of microbial origin useful in the composition according to the invention is (are) chosen from scleroglucan gum, xanthan gum, and mixtures thereof, more preferably scleroglucan gum.

[0061] The polysaccharide(s) useful in the composition of the invention are preferably present in a total content ranging from 0.1 to 20% by weight, preferably ranging from 0.5 to 15% by weight, preferentially from 1 to 10% by weight, relative to the weight of the composition.

[0062] Preferably, the polysaccharides of microbial origin are chosen from scleroglucan gum, xanthan gum, and mixtures thereof and they are present in a total content ranging from 0.1 to 20% by weight, preferably ranging from 0.5 to 15% by weight, preferentially from 0.1 to 10% by weight, relative to the weight of the composition.

[0063] More preferably, the scleroglucan gum is present in a total content ranging from 0.1 to 20% by weight, preferably ranging from 0.5 to 15% by weight, preferably from 0.1 to 10% by weight, relative to the weight of the composition. Cationic surfactant

[0064] The composition according to the invention may further comprise one or more cationic surfactants, preferably chosen from fatty amines, more preferably from fatty amidoamines.

[0065] Fatty amidoamine is understood to mean an amidoamine comprising, in general, at least one C6-C30 hydrocarbon chain. Preferably, the fatty amidoamines useful according to the invention are not quaternized.

[0066] Preferably, the fatty amidoamines useful according to the invention are not (poly)oxyalkylenated.

[0067] Among the fatty amidoamines useful according to the invention, mention may be made of the amidoamines of the following formula (I): RCONHR”N(R')2 (I) in which: - R represents a linear or branched, saturated or monovalent hydrocarbon radical unsaturated and substituted or unsubstituted, having from 5 to 29 carbon atoms, preferably from 7 to 23 carbon atoms, and in particular a linear or branched C5-C29, preferably C7-C23 alkyl radical, or a linear or branched C5-C29, preferably C7-C23 alkenyl radical; - R” represents a divalent hydrocarbon radical having less than 6 carbon atoms, preferably 2 to 4 carbon atoms, better still, 3 carbon atoms; and - R', identical or different, represent a monovalent hydrocarbon radical having less than 6 carbon atoms, preferably from 1 to 4 carbon atoms, linear or branched, saturated or unsaturated and substituted or unsubstituted, preferably a methyl radical.

[0068] The fatty amidoamines of formula (I) are, for example, chosen from oleamidopropyl dimethylamine, stearamidopropyl dimethylamine marketed by the company INOLEX CHEMICAL COMPANY under the name LEXAMINE S13, isostearamidopropyl dimethylamine, stearamidoethyl dimethylamine, laura-midopropyl dimethylamine, myristamidopropyl dimethylamine, behenami-dopropyl dimethylamine, dilinoleamidopropyl dimethylamine, palmitamidopropyl dimethylamine, ricinoleamindopropyl dimethylamine, soyamidopropyl dimethylamine, avocadoamidopropyl dimethylamine, cocamidopropyl dimethylamine, minkamidopropyl dimethylamine, oatamidopropyl dimethylamine, sesami-dopropyl dimethylamine, tallamidopropyl dimethylamine, olivamidopropyl dimethylamine, palmitamidopropyl dimethylamine, stearamidoethyldiethylamine, brassicamidopropyl dimethylamine and mixtures thereof.

[0069] Preferably, the fatty amidoamines are chosen from oleamidopropyl dimethylamine, stearamidopropyl dimethylamine, behenamidopropyl dimethylamine, brassicamidopropyl dimethylamine and mixtures thereof.

[0070] The fatty amidoamine(s) may be present in a total content ranging from 0.1 to 10% by weight, preferably from 0.5 to 5% by weight, preferentially from 1 to 4% by weight relative to the total weight of the composition.

[0071] Fatty amidoamines may also be present in neutralizing shampoos applied after the compositions of the invention containing alkali hydroxide to lower the pH of the fiber. Solvent

[0072] The composition of the invention may comprise water and / or a mixture of water and one or more organic solvent(s).

[0073] Among the suitable organic solvents, mention may be made more particularly of non-aromatic monoalcohols such as ethyl alcohol, isopropyl alcohol, or polyols or polyol ethers such as, for example, monomethyl, monoethyl and monobutyl ethers of ethylene glycol, propylene glycol or its ethers such as, for example, propylene glycol monomethyl ether, butylene glycol, dipropylene glycol and diethylene glycol alkyl ethers such as diethylene glycol monoethyl ether or monobutyl ether, or polyols such as glycerol and / or butanediol. Polyethylene glycols and polypropylene glycols, aromatic alcohols such as benzyl alcohol, and mixtures of all these compounds can also be used as solvents.

[0074] The water and organic solvents described above, if present, usually represent from 30 to 95% by weight, more preferably from 40 to 90% by weight, relative to the total weight of the composition.

[0075] The pH of the composition according to the invention generally varies from 7 to 13.5, better still from 7.5 to 13.

[0076] Preferably, the composition according to the invention is basic, more preferably the pH of the composition according to the invention is greater than 9, better between 12 and 13. Additional cosmetic agent(s)

[0077] The composition in accordance with the invention may also comprise one or more additional cosmetic agent(s).

[0078] The additional cosmetic agent(s) may be chosen from anionic, cationic, non-ionic, amphoteric, zwitterionic polymers or mixtures thereof other than the polysaccharides according to the invention; anionic surfactants, in particular sulfate, sulfonate or carboxylate surfactants, non-ionic surfactants, amphoteric surfactants, fatty substances, in particular fatty alcohols.

[0079] Of course, those skilled in the art will take care to choose this or these possible complementary compounds in such a way that the advantageous properties intrinsically attached to the composition in accordance with the invention are not, or not substantially, altered by the addition(s) envisaged.

[0080] The above additional cosmetic agents are generally present in an amount for each of them of between 0 and 20% by weight relative to the total weight of the composition.

[0081] Preferably, the composition is in the form of a cream or a cream gel.

[0082] The composition according to the invention may advantageously have a viscosity at 25°C ranging from 2 to 20 Pa.s, preferably ranging from 2 to 15 Pa.s and even more preferably ranging from 2.5 to 10 Pa.s.

[0083] The viscosity of the composition can be determined at 25°C using a rotary viscometer of the Rhéomat 180 type (Jean LAMY SA) equipped with a geometer of the anchor / bucket type Mobile 3 (MS-r 3) or Mobile 4 (MS-r4) with a rotation speed of 200 revolutions / minute and use of the calibration curves provided by the viscosimeter supplier. Process

[0084] The subject of the present invention is a method for the permanent deformation of keratin fibers, in particular for hair straightening, comprising the application to the fibers: i) at least one solid fatty ether(s), ii) at least one alkali hydroxide(s), and iii) at least one polysaccharide(s) of microbial origin, said solid fatty ether(s), said alkali hydroxide(s) and the said polysaccharides of microbial origin being applied within a single composition, or in separate compositions.

[0085] The implementation of this process makes it possible to obtain a permanent deformation of the keratin fibers, in particular a straightening, of good quality and lasting several shampoos while preserving the quality and integrity of the keratin fibers.

[0086] In addition, the implementation of this process makes it possible to provide good cosmetic properties, in particular shine and softness to the touch, to the keratin fibers.

[0087] The present invention finally relates to the use of a composition as described above for straightening keratin fibers, and in particular hair.

[0088] The following examples serve to illustrate the invention without, however, being limiting in nature.

[0089] In the following examples, all quantities are indicated as a percentage by mass of active ingredient (AI) relative to the total weight of the composition (unless otherwise stated). EXAMPLES Example 1: Alkaline straightening

[0090] Compositions A1 and B1 were prepared from the ingredients indicated in the table below in grams of active material:

[0091] Composition:

[0092] [Tables 1] Al (invention) B1 (comparative) Sodium hydroxide 2.0 2.0 Scleroglucan gum 1,3 - Hydroxyethyl cellulose - 1,3 Distearyl ether 10 10 Water Qsp 100 Qsp 100 PH 11 11 % naturalness 97.8% 96.5% Appearance after 24 hours Smooth cream gel Smooth cream gel Storage 1 week at 45 °C Smooth cream gel Curdled milk appearance on the surface Storage 2 months 45 °C Thick gel Fluid gel

[0093] The appearance was observed after 24 hours then after 1 week at 45°C then after 2 months at 45°C.

[0094] After 24 hours, compositions Al and B1 have sufficient viscosity to prevent the product from running and to guarantee consistent performance from root to tip.

[0095] After 1 week at 45°C, the composition of the invention remains stable, its appearance is identical. On the other hand, the comparative composition B1 has, after 1 week at 45°C, a curdled milk appearance on the surface leading to a less good distribution of the product and drips on the hair which leads to irregularities in results between the root and the tip in particular when applied under heat (heat of the scalp, under a helmet, heated curler).

[0096] After 2 months at 45°C, the composition A1 according to the invention still has sufficient viscosity which makes it possible to avoid dripping of the product and to guarantee regular performance from root to tip. On the contrary, the comparative composition B1 becomes fluid under the effect of heat which can lead to a less good distribution of the product and dripping on the hair and irregularities of results between the root and the tip in particular during application under heat (heat of the scalp, under a helmet, heated curler).

[0097] Furthermore, the composition Al of the invention has a very smooth, very shiny cream texture that is easy to apply and locate, allowing for even distribution throughout the hair. Furthermore, it is very easy to remove when rinsing.

[0098] The composition according to the invention makes it possible to obtain regular straightening over the entire hair, from root to tip while improving the naturalness of the composition. Example 2: Alkaline straightening

[0099] Compositions A2 and B2 were prepared from the ingredients indicated in the table below in grams of active material:

[0100] Composition:

[0101] [Tables2] A2(invention) B2(comparative) Sodium hydroxide 2.35 2.35 Xanthan gum 1,3 - Hydroxyethyl cellulose - 1,3 Distearyl ether 10 10 Water Qsp 100 Qsp 100 PH 13 13 Appearance after 24h Smooth cream gel Smooth cream gel Storage 2 months 45°C Thick gel Milk (liquid)

[0102] The appearance was observed after 24 hours then after 1 week at 45°C then after 2 months at 45°C.

[0103] After 24 hours, composition A2 has sufficient viscosity to prevent the product from running and to guarantee consistent performance from root to tip.

[0104] After 2 months at 45°C, composition A2 has sufficient viscosity to prevent product drips and to guarantee consistent performance from root to tip. On the contrary, comparative composition B2 becomes fluid under the effect of heat, resulting in poorer distribution of the product and drips on the hair and irregularities in results between the root and the tip, particularly when applied under heat (heat of the scalp, under a helmet, heated curler).

[0105] In other words, composition A2 of the invention has a smooth, very shiny cream texture that is easy to apply and locate, allowing for even distribution throughout the hair. In addition, it is very easy to remove when rinsing.

[0106] The composition according to the invention makes it possible to obtain regular straightening over the entire head of hair, from root to tip, while being more natural. Example 3: Alkaline straightening

[0107] Compositions A3 and A4 were prepared from the ingredients indicated in the table below in grams of active material:

[0108] Composition:

[0109] [Tables3] A3(invention) A4(invention) Sodium hydroxide 2.2 2.2 Benzyl alcohol 4.5 4.5 Denatured absolute ethyl alcohol 8 8 Scleroglucan gum 1.3 1.3 Xanthan gum 0.7 0.7 Distearyl ether 10 10 Butanediol - 1.5 Glycerin - 2 Steaeamidopropyl dimethylamine - 2 Water Qsp 100 Qsp 100

[0110] Compositions A3 and A4 according to the invention have a very smooth, very shiny cream texture that is easy to apply and localize, allowing for even distribution throughout the hair. In addition, it is very easy to remove when rinsing.

[0111] Compositions A3 and A4 according to the invention have sufficient viscosity to prevent the product from running and to guarantee consistent performance from root to tip.

[0112] The compositions according to the invention make it possible to obtain regular straightening throughout the hair, from root to tip.

[0113] Composition A4 makes it possible to obtain better sensory performances, particularly in terms of softness compared to composition A3.

Claims

Claims

1. Composition comprising: a) at least one solid fatty ether; b) at least one alkali hydroxide; c) at least one polysaccharide of microbial origin.

2. Composition according to claim 1, characterized in that the solid fatty ether(s) are of formula (I) RO-R' in which R and R', identical or different, denote a linear or branched alkyl or alkenyl radical, R and R' comprising at least 8 carbon atoms.

3. Composition according to any one of the preceding claims, characterized in that the solid fatty ether(s) are of formula (I) RO-R' in which R and R', identical or not, are radicals derived from oleic (C18), lauric (C12), palmitic (C16), myristic (C14), behenic (C22), stearic (C18), linoleic (C18), linolenic (Cl8), arachidic (C20) alcohols.

4. Composition according to any one of the preceding claims in which the solid fatty ether(s) is (are) of formula RO-R' in which R and R', identical or different, denote a linear or branched alkyl or alkenyl radical, C8-C40, preferably C10-C30, more preferably C14-C24; preferably R and R', identical or different, represent a linear alkyl radical C14-C24, preferably R and R' are identical and represent a linear alkyl radical C14-C24, better still C16-C22, better still R and R' denote a saturated radical, better still deriving from stearic alcohol (Cl8).

5. Composition according to any one of the preceding claims, in which the content of solid fatty ether(s) varies from 0.1 to 35%, preferably from 1 to 30% by weight, preferentially from 2.5 to 25% by weight, better still varies from 5 to 20% by weight and even better still from 7.5 to 15% by weight relative to the total weight of the composition.

6. Composition according to any one of the preceding claims, characterized in that the alkali metal hydroxide(s) are chosen from alkali metal and / or alkaline earth metal hydroxides, preferably chosen from sodium hydroxide, lithium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide and mixtures thereof, more preferably from sodium hydroxide, lithium hydroxide, calcium hydroxide and their mixtures, more preferably chosen from sodium hydroxide, calcium hydroxide and their mixtures.

7. Composition according to any one of the preceding claims, characterized in that the alkali metal hydroxide(s) is (or are) present in a total content ranging from 0.1 to 60% by weight, preferably from 0.5 to 55% by weight, better still from 1 to 50% by weight relative to the total weight of the composition containing them.

8. Composition according to any one of the preceding claims, characterized in that the polysaccharide(s) of microbial origin are chosen from xanthan gum, gellan gum, scleroglucan gum, and mixtures thereof, preferably from xanthan gum, scleroglucan gum, and mixtures thereof, more preferably scleroglucan gum.

9. Composition according to any one of the preceding claims, characterized in that the polysaccharide(s) of microbial origin is (or are) present in a total content ranging from 0.1 to 20% by weight, preferably ranging from 0.5 to 15% by weight, preferentially from 1 to 10% by weight, relative to the weight of the composition.

10. Composition according to any one of the preceding claims, comprising at least one cationic surfactant, preferably chosen from fatty amines, more preferably from fatty ami-domains.

11. Composition according to any one of the preceding claims, characterized in that the composition is basic, preferably with a pH greater than 9, better between 12 and 13.

12. A method of treating keratin fibers, preferably for the permanent deformation of hair, comprising the application to said fibers of the composition as defined in claims 1 to 11.

13. Use for the treatment of keratin fibers, preferably for the permanent deformation of keratin fibers, more preferably for the straightening of keratin fibers, of a composition as defined in any one of claims 1 to 11.