The present invention relates to a method for the treatment, preferably for the styling, of keratin fibres, in particular human keratin fibres, such as the hair, comprising the use, on the said keratin fibres, of at least one calcium salt, of at least one compound which generates phosphate PO ₄ ³ ions and of at least one organic alkaline agent.

The invention also relates to the use of a composition comprising these ingredients in the treatment of keratin fibres and preferably for the styling of keratin fibres, in particular embrittled hair, which is difficult to style and/or the volume of which is difficult to control, in particular under humid conditions

It is well known that hair may be sensitized or embrittled to varying degrees as a result of the action of atmospheric agents, such as light, water and moisture, and also repeated mechanical or chemical treatments, such as brushing, combing, washing, bleaching, permanent waving, relaxing and/or dyeing. These attacks detrimentally affect the hair fibre and reduce the mechanical properties thereof, such as the tensile strength, the breaking load and the elasticity, or its resistance to swelling in an aqueous medium. The hair is dull, coarse and brittle. The hair is difficult to disentangle and to style.

Substances which make it possible to protect the hair from such degradation have been sought for many years in the cosmetics industry; products which improve the cosmetic properties, in particular the disentangling, softness to the touch and volume of the head of hair, and which preserve or reinforce the intrinsic mechanical properties of keratin fibres, such as the tensile strength, the breaking load and the elasticity, are sought in particular.

Thus, shampoos have been proposed, in particular for sensitized hair, which combine a cationic polymer and a silicone, in order to obtain acceptable cosmetic performance qualities. However, there are several disadvantages to these compositions: presence of silicone, the environmental profile (biodegradability, water footprint) of which is not always optimum, rapid re-greasing of the hair accompanied by the hair being rendered lank. In addition, repeated applications of these compositions can sometimes have the effect of giving an unpleasant feel to the hair, a loss of volume and liveliness of the head of hair, and sometimes a lack of sheen. There thus exists a real need to develop methods for the treatment of keratin fibres which are capable of retaining, indeed even of improving, the quality of keratin fibres, in particular in terms of cosmetic properties, such as the feel or the appearance, and/or of mechanical properties, such as fortifying so as to reduce the risks of breaking, and also of making possible the styling of keratin fibres and more particularly of sensitized keratin fibres which are difficult to style and/or the volume of which is difficult to control, in particular under humid conditions.

This aim is achieved by the present invention, a subject-matter of which is in particular a method for the treatment of keratin fibres, in particular human keratin fibres, such as the hair, comprising the application, to the said keratin fibres, of one or more aqueous cosmetic compositions containing, taken together or separately in the said aqueous composition(s), the following ingredients:

(i) at least one alkali metal salt and/or at least one alkaline earth metal salt, preferably at least one calcium salt;

(ii) at least one compound which generates phosphate PC ³ ions; and iii) at least one organic alkaline agent.

It has in particular been discovered, surprisingly, that the calcium salts (i) and the compounds which generate phosphate ions (ii) react together in the presence of water to form an aqueous colloidal composition which makes it possible to obtain a significant improvement in the mechanical properties of keratin fibres, without detrimentally affecting the quality of the fibre. More particularly, this aqueous colloidal composition confers, on keratin fibres, a better flexural resistance, corresponding to an increased perception of the body and of the strength of the hair, indeed even a feeling of sheathed keratin fibres by the user.

The Applicant has thus found that the method according to the invention makes it possible to improve the cosmetic and mechanical properties conferred on keratin fibres, in particular on hair sensitized by the action of external atmospheric agents, such as light and bad weather, and/or the action of mechanical or chemical treatments, such as brushing, combing, dyeing, bleaching, permanent waving and/or relaxing.

It has also been found that the keratin fibres treated according to the method of the invention exhibit a better quality of the fibre. The improvement in the quality of the keratin fibres can be evaluated by a better resistance to breaking, a better texturizing of or provision of body to the hair, a better flexural resistance and also by a perception of body and of strength of the hair, and/or a feeling of sheathed hair, by the user.

In particular, the method according to the invention makes it possible to obtain a better texturizing of keratin fibres and thus to improve the styling of fibres which are difficult to style and/or the volume of which is difficult to control, in particular under humid conditions.

It has also been discovered, surprisingly, that an organic alkaline agent, preferably an amino acid, makes it possible to stabilize a composition comprising the calcium salts (i) and the compounds which generate phosphate ions (ii) according to the invention.

Another subject-matter of the present invention relates to the use of an aqueous composition comprising:

(i) at least one alkali metal salt and/or at least one alkaline earth metal salt, preferably at least one calcium salt,

(ii) at least one compound which generates phosphate PO ₄ ³ ions, and iii) at least one organic alkaline agent,

in the treatment of keratin fibres, in particular human keratin fibres, such as the hair.

Other characteristics, aspects, objects and advantages of the present invention will become even more clearly apparent on reading the following description and examples.

Within the meaning of the invention, unless otherwise indicated:

- the limits of a range of values are included within this range, in particular in the expressions "between ... and ...", "ranging from ... to ..." and "extending from ... to ...";

- the expression "at least one" used in the present description is equivalent to the expression "one or more", and can be substituted for it;

- the term "keratin fibres", according to the present patent application, preferably denotes human keratin fibres and more particularly the hair.

Preferably, the method according to the invention is a method for the styling of keratin fibres, in particular human keratin fibres, such as the hair. According to a preferred embodiment of the invention, the aqueous composition(s) employed in the method according to the invention are devoid of silicone and/or of cationic polymer.

The expression "devoid of silicone" is understood to mean that the composition does not comprise silicone, or that the silicone(s) present in the composition are included in a total content of less than or equal to 0.1% by weight, preferably of less than 0.05% by weight, with respect to the total weight of the composition, better still is free from silicone (0% by weight).

Within the meaning of the present invention, the term "silicone" is understood to mean any organosilicon polymer or oligomer having a linear or cyclic, branched or crosslinked, structure, of variable molecular weight, obtained by polymerization and/or by polycondensation of suitably functionalized silanes and essentially constituted by a repetition of main units in which the silicon atoms are connected to one another by oxygen atoms (siloxane -Si-O-Si- bond), optionally substituted hydrocarbon radicals being directly connected via a carbon atom to the said silicon atoms; and more particularly dialkylsiloxane polymers, aminated silicones or dimethiconols.

The expression "devoid of cationic polymer" is understood to mean that the composition does not comprise cationic polymer, or that the cationic polymer(s) present in the composition are included in a total content of less than or equal to 0.1% by weight, preferably of less than 0.05% by weight, with respect to the total weight of the composition, better still is free from cationic polymer (0% by weight).

Within the meaning of the present invention, the expression "cationic polymer" denotes any non-silicone polymer containing cationic groups and/or groups which can be ionized to give cationic groups and not containing anionic groups and/or groups which can be ionized to give anionic groups.

The alkali metal and/or alkaline earth metal salts

The method according to the invention comprises the application, to keratin fibres, of one or more aqueous cosmetic compositions containing at least one alkali metal salt and/or at least one alkaline earth metal salt.

Preferably, the alkali metal and/or alkaline earth metal salt(s) (i) are chosen from calcium salts, magnesium salts, sodium salts, potassium salts and their mixtures.

More preferentially, the alkali metal and/or alkaline earth metal salt(s) (i) are calcium salts. More preferentially still, the alkali metal and/or alkaline earth metal salt(s) (i) are chosen from calcium hydroxide, calcium oxides, calcium halides, calcium nitrate, calcium hydrogencarbonate and their mixtures.

The compounds which generate phosphate PO ions

The method according to the invention comprises the application, to keratin fibres, of one or more aqueous cosmetic compositions containing at least one compound which generates phosphate PO4 ³ ions.

Within the meaning of the invention, the term "compound which generates phosphate PO4 ³ ions" is understood to mean a compound capable of releasing PO4 ³ ions in aqueous solution.

Preferably, the compound(s) which generates(s) phosphate PO4 ³ ions (ii) are chosen from a) orthophosphoric acid H3PO4, b) salts, for example ammonium or alkali metal, of a PO4 ³ anion, of an HPO4 ² anion, of an H2PO4 anion, or a mixture of these salts, c) salts of an anion of oligomeric phosphate type, such as salts of polyphosphates (or catena-polyphosphate) of following general formula:

[0(P0 )„] ⁽ⁿ⁺²⁾ - in which n varies from 2 to 10 (and in particular salts of tripolyphosphate type), d) salts of a trimetaphosphate (PO3) ³ anion, or a mixture of these compounds.

More preferentially, the compound which generates phosphate PO4 ³ ions (ii) is orthophosphoric acid H3PO4.

Preferably, the ratio of the total molar concentration of alkali metal and/or alkaline earth metal salt(s) (i) employed in the method according to the invention, on the one hand, to the total molar concentration of compound which generates phosphate PO4 ³ ions (ii) employed in the method according to the invention, on the other hand, is between 1 and 8, more preferentially between 1 and 6, more preferentially still between 1 and 5, better still between 1 and 4, even better still between 1 and 3.5, and indeed even between 2 and 3.

Preferably, the ratio of the total molar concentration of calcium salt(s) (i) employed in the method according to the invention, on the one hand, to the total molar concentration of compound which generates phosphate PO4 ³ ions (ii) employed in the method according to the invention, on the other hand, is between 1 and 8, more preferentially between 1 and 6, more preferentially still between 1 and 5, better still between 1 and 4, even better still between 1 and 3.5, and indeed even between 2 and

3.

Preferably, the ratio of the total molar concentration of calcium salt(s) (i) employed in the method according to the invention, on the one hand, to the total molar concentration of orthophosphoric acid H ₃ PO ₄ employed in the method according to the invention, on the other hand, is between 1 and 8, more preferentially between 1 and 6, more preferentially still between 1 and 5, better still between 1 and 4, even better still between 1 and 3.5, and indeed even between 2 and 3.

The organic alkaline agents

The method according to the invention comprises the application, to keratin fibres, of one or more aqueous cosmetic compositions containing at least one organic alkaline agent.

Preferably, the organic alkaline agent(s) are chosen from organic amines, the pK _b of which at 25°C is less than 12, more preferentially less than 10 and more advantageously still less than 6. It should be noted that it is the pK _b corresponding to the functional group of highest basicity. In addition, the organic amines do not comprise an alkyl or alkenyl fatty chain comprising more than ten carbon atoms.

The organic alkaline agent(s) can be chosen from alkanolamines, in particular mono-, di- or trihydroxy(Ci-C ₆ )alkylamines, such as 2-amino-2-methylpropanol, oxyethylenated and/or oxypropylenated ethylenediamines, amino acids, polyamines of following formula (VII), and their mixtures:

in which formula (VII) W is a divalent Ci to Ce alkylene radical optionally substituted by one or more hydroxyl groups or by a Ci to Ce alkyl radical, and/or optionally interrupted by one or more heteroatoms, such as O, or NR _U , and R _x , R _y , R _z , R _t and R _u , which are identical or different, represent a hydrogen atom or a Ci to Ce alkyl, Ci to Ce hydroxyalkyl or Ci to Ce aminoalkyl radical.

Mention may be made, as example of amines of formula (VII), of 1,3- diaminopropane, l,3-diamino-2-propanol, spermine or spermidine.

The term "alkanolamine" is understood to mean an organic amine comprising a primary, secondary or tertiary amine functional group, and one or more linear or branched Ci to Cs alkyl groups carrying one or more hydroxyl radicals. Organic amines chosen from alkanolamines, such as monoalkanolamines, dialkanolamines or trialkanolamines, comprising from one to three identical or different Ci to C4 hydroxy alkyl radicals are in particular suitable for the implementation of the invention.

Mention may be made, among the compounds of this type, of monoethanolamine (MEA), diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, N,N-dimethylethanolamine, 2-amino-2-methyl- 1-propanol, triisopropanolamine, 2-amino-2-methyl- 1,3 -propanediol, 3-amino- 1,2-propanediol, 3- dimethylamino- 1,2-propanediol or tris(hydroxymethyl)aminomethane.

More particularly, the amino acids which can be used as organic alkaline agents are of natural or synthetic origin, in their L, D or racemic form, and comprise at least one acid functional group chosen more particularly from carboxylic acid, sulfonic acid, phosphonic acid or phosphoric acid functional groups. The amino acids can be in neutral or ionic form.

Advantageously, the amino acids are natural or synthetic a-amino acids which comprise a carbon C atom carrying an amino group, a carboxyl group, a hydrogen atom and a side group which can be a hydrogen atom (case of glycine), any other monovalent organic group or a ring comprising the said carbon C atom, the nitrogen atom of the said amino group and several additional carbon atoms, preferably 3 to 4 additional carbon atoms.

The side groups can in particular be alkyl groups (case of alanine, valine, leucine or isoleucine), substituted alkyl groups (case of threonine, serine, methionine, cysteine, asparagine, aspartic acid, glutamic acid, glutamine, arginine and lysine), arylalkyl groups (case of phenylalanine and tryptophan), substituted arylalkyl groups (case of tyrosine) or heteroalkyl groups (case of histidine).

The side group can in particular be a 5-membered ring comprising the said carbon C atom, the nitrogen atom of the said amino group and 3 additional carbon atoms, such as for proline.

These a-amino acids are listed in particular in Harper et al. (1977), Review of Physiological Chemistry, 16th edition, Lange Medical Publications, pages 21-24.

The term "synthetic a-amino acid" is understood to mean an a-amino acid which is not incorporated in a protein under the control of mRNA, such as, for example, a fluorinated a-amino acid, such as fluoroalanine, trimethylsilylalanine or an a-amino acid such as:

where m is an integer from 1 to 6 and m is an integer from 1 to 12.

Synthetic amino acids are, furthermore, described in Williams (Ed.), Synthesis of Optically Active a- Amino Acids, Pergamon Press (1989); Evans el ah, J. Amer. Chem. Soc., 112, 4011-4030 (1990); Pu et ah, J. Amer. Chem. Soc., 56, 1280- 1283 (1991); or Williams et al, J. Amer. Chem. Soc., 113, 9276-9286 (1991).

More generally, the preferred a-amino acids are of the following general formula:

W-NH-CH-COOH

1 L

in which:

L represents an alkyl group optionally interrupted by an oxygen atom and/or a sulfur atom and/or a nitrogen atom, the said nitrogen atom carrying a hydrogen atom or an alkyl, aryl, arylalkyl, alkylaryl, heteroaryl or heteroarylalkyl radical, and the said alkyl group optionally being substituted by one or more radicals chosen from -OH, -Nth, guanidino, carboxyl, carbamoyl, thiol, aryl (itself optionally substituted by one or more identical or different T radicals, as defined below) or heteroaryl (itself optionally substituted by one or more identical or different T radicals, as defined below);

W represents a hydrogen atom or else L and W together represent an optionally substituted alkylene chain;

T represents hydroxyl, amino, guanidino, carboxyl, thiol, alkylthio, alkylamino, carbamoyl, dialkylamino, aryl, arylalkyl, alkylaryl, heteroaryl, alkylheteroaryl or heteroarylalkyl.

The term "alkylene" is understood to mean a linear or branched aliphatic hydrocarbon chain.

The substituents of the alkylene chain are chosen from the T groups defined above.

The term "alkyl" is generally understood to mean a linear or branched aliphatic hydrocarbon chain comprising from 1 to 18 carbon atoms, preferably from 1 to 10 carbon atoms and in particular from 1 to 6 carbon atoms. The term "aryl" generally denotes an aromatic carbocyclic radical comprising from 6 to 18 carbon atoms, preferably from 6 to 10 carbon atoms.

Aryl is mono- or polycyclic and preferably mono-, bi- or tricyclic. When the carbocyclic radical comprises more than one cyclic nucleus, the cyclic nuclei can be condensed in pairs or connected in pairs by s bonds.

The term "heteroaryl" is generally understood to mean heterocyclic radicals comprising one or more heteroatoms chosen from O, S and N.

Within the meaning of the invention, the expression "optionally interrupted by O and/or S and/or N" means that any carbon atom of the hydrocarbon chain can be replaced by an oxygen and/or sulfur and/or nitrogen atom, it not being possible for this carbon atom to be located at one of the ends of the said hydrocarbon chain. The hydrocarbon chain, which can be alkyl, can comprise several oxygen and/or sulfur and/or nitrogen atoms, the heteroatoms preferably being separated from one another by at least one carbon atom, better still by at least two carbon atoms.

The organic amines can also be chosen from organic amines of heterocyclic type. Mention may in particular be made of pyridine, piperidine, imidazole, triazole, tetrazole or benzimidazole

The organic amines can also be chosen from amino acid dipeptides. Mention may in particular be made, as amino acid dipeptides which can be used in the present invention, of carnosine, anserine and balenine.

The organic amine can also be chosen from compounds comprising a guanidine functional group. Mention may in particular be made, as amines of this type which can be used in the present invention, in addition, of creatine, creatinine, 1,1- dimethylguanidine, 1,1-diethylguanidine, glycocy amine, metformin, agmatine, N- amidinoalanine, 3-guanidinopropionic acid, 4-guanidinobutyric acid and 2- ([amino(imino)methyl]amino)ethane- 1 -sulfonic acid.

Very particularly preferably, the organic alkaline agent(s) are chosen from natural amino acids, synthetic amino acids, their salts and their mixtures; more preferentially still from natural amino acids and their salts; and better still from lysine, arginine, histidine, their salts and their mixtures.

Preferably, the ratio of the total molar concentration of organic alkaline agent(s) (iii) employed in the method according to the invention, on the one hand, to the total molar concentration of alkali metal and/or alkaline earth metal salt(s) (i) employed in the method according to the invention, on the other hand, is between 0.1 and 4, preferably between 0.2 and 3 and more preferentially between 0.3 and 2.5.

Preferably, the ratio of the total molar concentration of organic alkaline agent(s) (iii) employed in the method according to the invention, on the one hand, to the total molar concentration of calcium salt(s) employed in the method according to the invention, on the other hand, is between 0.1 and 4, preferably between 0.2 and 3 and more preferentially between 0.3 and 2.5.

Preferably, the ratio of the total molar concentration of organic alkaline agent(s) (iii) chosen from lysine, arginine and/or histidine employed in the method according to the invention, on the one hand, to the total molar concentration of calcium salt(s) employed in the method according to the invention, on the other hand, is between 0.1 and 4, preferably between 0.2 and 3 and more preferentially between 0.3 and 2.5.

The method for the treatment of keratin fibres according to the invention comprises the application, to the said keratin fibres, of one or more aqueous cosmetic compositions containing, taken together or separately in the said aqueous composition(s), the ingredients as described above.

Advantageously, the aqueous composition(s) employed in the method according to the invention have a pH of between 7 and 12, more preferentially of between 7 and 11 and more preferentially still of between 7 and 9.5.

According to a first specific embodiment of the invention:

- the alkali metal and/or alkaline earth metal salt(s) (i) and the organic alkaline agent(s) (iii) are included in an aqueous composition (A), and

- the compound(s) which generate(s) phosphate PO4 ³ ions (ii) is (are) included in an aqueous composition (B), distinct from the composition (A).

According to this first embodiment, the said aqueous composition (A) and the said composition (B) are preferably applied sequentially to said keratin fibres.

Within the meaning of the invention, the term "sequentially" is understood to mean that the said composition (A) is applied to the keratin fibres before the said composition (B), or conversely that the said composition (A) is applied to the keratin fibres before the said composition (B). In other words, the said compositions (A) and (B) are not applied to the keratin fibres simultaneously. According to this first embodiment:

- the total molar concentration of alkali metal and/or alkaline earth metal salt(s) (i), present in the said aqueous composition (A), is preferably between 0.1 and 4 mol/1, better still between 0.5 and 3 mol/1 and even better still between 1 and 2 mol/1;

- the total molar concentration of organic alkaline agent(s) (iii), present in the said aqueous composition (A), is preferably between 0.2 and 8 mol/1, better still between 1 and 6 mol/1 and even better still between 2 and 4 mol/1; and/or

- the total molar concentration of compound which generates phosphate PC ³ ions (ii), present in the said aqueous composition (B), is preferably between 0.03 and 4 mol/1, better still between 0.17 and 3 mol/1 and even better still between 0.33 and 2 mol/1.

More preferentially:

- the total molar concentration of calcium salt(s), present in the said aqueous composition (A), is preferably between 0.1 and 4 mol/1, better still between 0.5 and 3 mol/1 and even better still between 1 and 2 mol/1;

- the total molar concentration of organic alkaline agent(s) (iii) chosen from lysine, arginine and/or histidine, present in the said aqueous composition (A), is preferably between 0.2 and 8 mol/1, better still between 1 and 6 mol/1 and even better still between 2 and 4 mol/1; and/or

- the total molar concentration of orthophosphoric acid H3PO4, present in the said aqueous composition (B), is preferably between 0.03 and 4 mol/1, better still between 0.17 and 3 mol/1 and even better still between 0.33 and 2 mol/1.

According to this first embodiment, the said compositions (A) and (B) employed in the method according to the invention preferably have a pH of between 7 and 12, more preferentially of between 7 and 11 and more preferentially still of between 7 and 9.5.

Still according to this first embodiment of the invention:

- the ratio of the total molar concentration of alkali metal and/or alkaline earth metal salt(s) (i) included in the said composition (A), on the one hand, to the total molar concentration of compound which generates phosphate PO4 ³ ions (ii) included in the said composition (B), on the other hand, preferably ranges from 1 to 8, more preferentially from 1 to 6, more preferentially still from 1 to 5, better still from 1 to 4, even better still from 1 to 3.5, and indeed even from 2 to 3;

- the ratio of the total molar concentration of calcium salt(s) (i) included in the said composition (A), on the one hand, to the total molar concentration of compound which generates phosphate PO4 ³ ions (ii) included in the said composition (B), on the other hand, preferably ranges from 1 to 8, more preferentially from 1 to 6, more preferentially still from 1 to 5, better still from 1 to 4, even better still from 1 to 3.5, and indeed even from 2 to 3;

- the ratio of the total molar concentration of calcium salt(s) (i) included in the said composition (A), on the one hand, to the total molar concentration of orthophosphoric acid H3PO4 included in the said composition (B), on the other hand, preferably ranges from 1 to 8, more preferentially from 1 to 6, more preferentially still from 1 to 5, better still from 1 to 4, even better still from 1 to 3.5, and indeed even from 2 to 3.

According to a second specific embodiment of the invention, the method according to the invention comprises:

- in a first step, the mixing of the aqueous composition (A) with the aqueous composition (B) as are described above in the first specific embodiment of the invention, in order to obtain an aqueous composition (C), then

- in a second step, the application of the said composition (C) to the keratin fibres.

All the characteristics and preferences relating to the aqueous compositions (A) and (B) described above in the first specific embodiment of the invention are respectively applicable to the aqueous compositions (A) and (B) employed in this second specific embodiment.

In addition, according to this second specific embodiment:

- the said composition (C) employed in the method according to the invention preferably has a pH of between 7 and 12, more preferentially of between 7 and 11 and more preferentially still of between 7 and 9.5;

- the ratio of the total molar concentration of alkali metal and/or alkaline earth metal salt(s) (i) included in the said composition (C), on the one hand, to the total molar concentration of compound which generates phosphate PO4 ³ ions (ii) included in the said composition (C), on the other hand, preferably ranges from 1 to 8, more preferentially from 1 to 6, more preferentially still from 1 to 5, better still from 1 to 4, even better still from 1 to 3.5, and indeed even from 2 to 3;

- the ratio of the total molar concentration of calcium salt(s) (i) included in the said composition (C), on the one hand, to the total molar concentration of compound which generates phosphate PO4 ³ ions (ii) included in the said composition (C), on the other hand, preferably ranges from 1 to 8, more preferentially from 1 to 6, more preferentially still from 1 to 5, better still from 1 to 4, even better still from 1 to 3.5, and indeed even from 2 to 3;

- the ratio of the total molar concentration of calcium salt(s) (i) included in the said composition (C), on the one hand, to the total molar concentration of orthophosphoric acid H3PO4 included in the said composition (C), on the other hand, preferably ranges from 1 to 8, more preferentially from 1 to 6, more preferentially still from 1 to 5, better still from 1 to 4, even better still from 1 to 3.5, and indeed even from 2 to 3.

Preferably, during the application of the aqueous composition (A) or of the aqueous composition (B) to the keratin fibres according to the first specific embodiment described above, or during the application of the aqueous composition (C) to the keratin fibres according to the second specific embodiment described above, the ratio by weight of the mass of aqueous composition, on the one hand, to the mass of keratin fibres to be treated, on the other hand, is between 0.1 and 20, more preferentially between 0.5 and 10.

Advantageously, according to the method of the invention, the leave-on time of each aqueous composition on the keratin fibres is preferably between 1 and 40 minutes, more preferentially between 5 and 35 minutes and more preferentially still between 10 and 30 minutes.

Preferentially, after the application of the aqueous composition (A) and/or of the aqueous composition (B) to the keratin fibres according to the first specific embodiment described above, or after the application of the aqueous composition (C) to the keratin fibres according to the second specific embodiment described above, the aqueous composition(s) are respectively left on the said fibres for a leave-on time of between 1 and 40 minutes, more preferentially still between 5 and 35 minutes and even better still between 10 and 30 minutes.

More preferentially still, the keratin fibres are kept, during the leave-on time, at a temperature of between 32°C and 50°C, preferably between 32°C and 45°C.

The method for the treatment of keratin fibres according to the invention can optionally comprise, in addition, after the stage of application, to the said fibres, of one or more aqueous cosmetic compositions containing, taken together or separately in the said aqueous composition(s), the ingredients as described above, a step of rinsing with water and/or a step of drying the said fibres.

A subject-matter of the present invention also relates to the use of an aqueous composition comprising at least one alkali metal salt and/or at least one alkaline earth metal salt, preferably at least one calcium salt, (i), at least one compound which generates phosphate PO4 ³ ions (ii) and at least one organic alkaline agent (iii), all as described above, in the treatment of keratin fibres, in particular human keratin fibres, such as the hair.

Preferably, this aqueous composition is used for the styling of keratin fibres, in particular human keratin fibres, such as the hair.

A subject-matter of the invention also relates to a ready-for-use aqueous composition (M) comprising at least one alkali metal salt and/or at least one alkaline earth metal salt, preferably at least one calcium salt, (i), at least one compound which generates phosphate PO4 ³ ions (ii) and at least one organic alkaline agent (iii), all as described above, for use in the treatment of keratin fibres, in particular human keratin fibres, such as the hair.

Preferably, this aqueous composition (M) is used for the styling of keratin fibres, in particular human keratin fibres, such as the hair.

Another subject-matter relates to a device for the treatment of keratin fibres, in particular human keratin fibres, such as the hair, comprising at least one first compartment containing the composition (A) as described above and at least one second compartment containing the composition (B) as described above.

Preferably, this device is used for the styling of keratin fibres, in particular human keratin fibres, such as the hair.

The examples which follow serve to illustrate the invention without, however, exhibiting a limiting nature.

Examples:

Preparation of the aqueous compositions:

Aqueous composition (A): 0.148 mol of L-lysine and 0.075 mol de calcium nitrate tetrahydrate Ca(N0 ₃ ) ₂ . 4H2O are added to 75 ml of demineralized water. The mixture is subsequently stirred to dissolution in order to obtain an aqueous composition (A) with a total molar concentration of calcium nitrate tetrahydrate of 1 mol/1 and a total molar concentration of L-lysine of 1.973 mol/1, and a pH of 9.92.

Aqueous composition (B): 100 ml of a 1M orthophosphoric acid H3PO4 solution are introduced into a 500 ml beaker (pH = 1.20). Demineralized water and a 20% aqueous ammonia solution were subsequently added in order to obtain an aqueous composition (B) with a pH = 9 and a total molar concentration of orthophosphoric acid of 0.333 mol/1.

Aqueous composition (C): 37.5 ml of the aqueous composition (A) are rapidly added to 37.5 ml of the aqueous composition (B). The mixture is then stirred until an aqueous composition (C) is obtained, in the form of a milk, with a pH of 9.2.

Aqueous composition (A'): 0.751 mol of L-lysine and 0.375 mol of calcium nitrate tetrahydrate Ca(N0 ₃ ) ₂ . 4H2O are added to 188 ml of demineralized water. The mixture is subsequently stirred to dissolution in order to obtain an aqueous composition (A) with a total molar concentration of calcium nitrate tetrahydrate of 1.995 mol/1 and a total molar concentration of L-lysine of 3.995 mol/1, and a pH of 9.8.

Aqueous composition (C): 250 ml of the aqueous composition (A') are rapidly added to 250 ml of the aqueous composition (B). The mixture is then stirred until an aqueous composition (C) is obtained, in the form of a milk, with a pH of 9.34.

Aqueous composition (A"): 0.148 mol of L-arginine and 0.075 mol of calcium nitrate tetrahydrate Ca(N0 ₃ ) ₂ . 4¾0 are added to 75 ml of demineralized water. The mixture is subsequently stirred to dissolution in order to obtain an aqueous composition (A") with a total molar concentration of calcium nitrate tetrahydrate of 1 mol/l and a total molar concentration of L-arginine of 1.973 mol/l, and a pH of 11.30.

Aqueous composition (C"): 37.5 ml of the aqueous composition (A") are rapidly added to 37.5 ml of the aqueous composition (B). The mixture is then stirred until an aqueous composition (C") is obtained, in the form of a milk, with a pH of 9.18.

Aqueous composition (A'"): 0.751 mol of L-arginine and 0.375 mol of calcium nitrate tetrahydrate Ca(N0 ₃ ) ₂ . 4¾0 are added to 188 ml of demineralized water. The mixture is subsequently stirred to dissolution in order to obtain an aqueous composition (A'") with a total molar concentration of calcium nitrate tetrahydrate of 1.995 mol/1 and a total molar concentration of L-arginine of 3.995 mol/1, and a pH of 10.90.

Aqueous composition 250 ml of the aqueous composition (A'") are rapidly added

to 250 ml of the aqueous composition (B). The mixture is then stirred until an aqueous composition (C") is obtained, in the form of a milk, with a pH of 9.39.

Procedure

Locks of sensitized Caucasian hair (bleached hair of alkaline solubility SA16), each of 2.7 grams, were used in the methods according to the invention described below.

Treatment method Ml according to the invention:

A lock of hair was placed in a glass chute. 10 ml of the aqueous composition (C) prepared beforehand are subsequently applied to the lock. The lock is subsequently left standing at 40°C for 30 minutes. The lock is then superficially dried, rinsed with water and finally allowed to dry in the open air for 10 hours.

Treatment method M2 according to the invention:

A lock of hair was placed in a first glass chute. 10 ml of the aqueous composition (B) prepared beforehand are subsequently applied to the lock. The lock is subsequently left standing at 40°C for 30 minutes.

The lock of hair treated with the aqueous composition (B) is subsequently placed in a second glass chute. Then, 10 ml of the aqueous composition (A) prepared beforehand are subsequently applied to the lock. The lock is then left standing at 40°C for 30 minutes.

The lock is subsequently superficially dried, rinsed with water and finally allowed to dry in the open air for 10 hours.

Treatment method M3 according to the invention:

A lock of hair was placed in a first glass chute. 10 ml of the aqueous composition (A) prepared beforehand are subsequently applied to the lock. The lock is subsequently left standing at 40°C for 30 minutes. The lock of hair treated with the aqueous composition (A) is subsequently placed in a second glass chute. Then, 10 ml of the aqueous composition (B) prepared beforehand are subsequently applied to the lock. The lock is then left standing at 40°C for 30 minutes.

The lock is subsequently superficially dried, rinsed with water and finally allowed to dry in the open air for 10 hours.

Flexural test on the treated locks

A flexural test was carried out on each lock of hair used respectively in the treatment methods Ml to M3 according to the invention. For this test, 150 mg of each lock of hair treated according to the various methods Ml to M3 described above are gathered together and then cut into small locks with a length of 3.5 cm. A plastic cable clamp was subsequently attached to the middle of each small lock in order to prevent the hairs from sliding with regard to one another.

Flexural test:

During the flexion of a small lock of hair, each keratin fibre undergoes extension and compression stresses, respectively in the outside and inside of its curve. The measurement of the force required to bend a small lock of fibres can either suggest the presence of a deposit of material at the surface of the fibre (for example the increase in the flexural force after application of a styling polymer) or indicate a loss of structural integrity of the individual hair or a partial decuticulation (decrease in the flexural force observed after the application of a reducing agent, such as thioglycolic acid, or the application of a bleaching treatment). The flexural force may be linked to a perception of the consumer of the body or of the strength of a head of hair or to a feeling of sheathed individual hair.

Consequently, the greater the flexural force of the hair, the greater the texturizing of the individual hair and the more the consumer has the sensation of material between the fingers to the touch. This property is accompanied, generally, by a facilitated styling of the head of hair.

Each small lock with a length of 3.5 cm is fixed in a sample holder attached to the arm of a Zwickiline Z2.5 (Zwick, Germany) mechanical testing device equipped with a cell for measurements of 10 newtons (N). The two parts of the device are brought together at a constant rate of displacement of 10 mm/min, which brings about the flexion of the hair with 3 contact points. The force generated by the resistance of the hair to the bending is measured as a function of the displacement. A force/displacement curve is recorded and makes it possible to determine the maximum flexural force of the hair. The impact of the hair treatments on the flexural properties is obtained by comparing the maximum flexural force of control small locks (untreated small locks of bleached Caucasian hair of alkaline solubility SA16) with that of treated small locks.

For measurements in the dry state (dry flexural force), the small locks of hair are conditioned at 25 °C and 45% relative humidity.

Results:

The results obtained are presented in the table below.

It is found that the flexural force of the hair treated according to a method according to the present invention is greater than the flexural force of the untreated hair.

Styling test

The test was carried out on a malleable head (Suky head, Japanese hair 35/45 cm, reference 772104, of Andrex) according to the procedure described below, in order to demonstrate that the method according to the present invention makes possible form retention of the head of hair over time, in particular under humid conditions. Procedure:

1 g of the aqueous composition (C) and then 10 g of water (pH = 9) are introduced into a first manual spray.

10 g of an aqueous solution comprising 2-amino-2-methylpropanol having an identical pH to the solution included in the first manual spray are introduced into a second manual spray.

While looking at the malleable head from the front, the solution contained in the second spray is sprayed uniformly over the left side of the head of hair and the solution contained in the first spray is sprayed uniformly over the right side of the head of hair. The malleable head is left standing and then a first photo of it is taken after one hour. The malleable head thus treated is subsequently placed for 24 h in a glovebox maintained at a degree of humidity of 80%. A new photo (second photo) of the malleable head is subsequently taken.

Results:

In the first photo, no difference was observed between the left side and the right side of the head of hair. In the second photo, a difference was observed between the left side of the head of hair, where the hair has completely covered the left eye, and the right side of the head of hair, where the right eye is barely masked by the hair.

The method according to the invention thus makes it possible to obtain a good hold of the hairstyle, in particular over time and under humid conditions.