WO2025242813A1

WO2025242813A1 - Hair treatment process based on a silicate compound and a phosphoric compound

Info

Publication number: WO2025242813A1
Application number: PCT/EP2025/064156
Authority: WO
Inventors: Xavier FROGNEUX-PLE; Chloé SEYRIG; Clément Sanchez
Original assignee: LOreal SA; College de France
Current assignee: LOreal SA; College de France
Priority date: 2024-05-23
Filing date: 2025-05-22
Publication date: 2025-11-27
Anticipated expiration: 2026-11-23
Also published as: FR3162358A1

Abstract

The present invention relates to a hair treatment process using a composition comprising at least one silicate compound, a composition comprising at least one particular phosphoric compound and another composition comprising at least one alkali metal salt and/or at least one alkaline-earth metal salt. The present invention also relates to the use of a composition comprising at least one silicate compound and of another composition comprising at least one particular phosphoric compound, for repairing and/or preventing hair breakage.

Description

HAIR TREATMENT PROCESS BASED ON A SILICATE COMPOUND AND A PHOSPHORIC COMPOUND

The present invention relates to a hair treatment process using a composition comprising at least one silicate compound, a composition comprising at least one particular phosphoric compound and another composition comprising at least one alkali metal salt and/or at least one alkaline-earth metal salt.

The present invention also relates to the use of a composition comprising at least one silicate compound and of another composition comprising at least one particular phosphoric compound, for repairing and/or preventing hair breakage.

The hair may be damaged and made brittle by external atmospheric agents such as pollution and bad weather, and also by mechanical or chemical treatments, or certain routines, such as brushing, combing, dyeing, bleaching, permanent-waving, straightening and/or repeated washing. The hair may then end up damaged and may in the long run become dry, coarse, brittle, dull, split and/or limp.

Thus, to overcome these drawbacks, it is common practice to resort to haircare processes intended for conditioning the hair by giving it satisfactory cosmetic properties, notably smoothness, sheen, a soft feel, suppleness, lightness, and also good disentangling properties leading to easy combing, and good manageability of the hair which is thus easier to style and holds its shape. However, the conditioning effect obtained via these haircare processes fades out rapidly over time, and does not strengthen the hair cortex. Such treatments do not afford a very long-lasting effect over time.

By way of example, shampoos are usually used to clean the hair, affording it satisfactory cosmetic properties, but these compositions do not improve the quality of the fibre. In particular, they do not allow the density of bonds between the proteins present in the cortex of the fibre to be improved, so as to repair it or reduce breakage thereof, for example during combing or disentangling.

There is thus still a real need to develop a process for treating the hair, preferably damaged and/or sensitized hair, which is capable of preserving or even improving the quality of said hair, notably by increasing the density of bonds between the proteins present in the cortex of this hair, thus making it possible to repair it and/or reduce breakage thereof and/or to strengthen it for the purpose of a treatment liable to damage it, for example during bleaching, combing or disentangling. Moreover, the formulation of environmentally-friendly cosmetic products, i.e. products whose design and development take account of environmental issues, is becoming a major preoccupation for contributing toward meeting the global challenges.

It is therefore essential to propose more sustainable compositions and/or preparation processes and/or ingredients, thus enabling these environmental challenges to be met.

In this context, it is important to develop processes for preparing cosmetic products and/or cosmetic ingredients with an improved carbon footprint, that are capable of reducing the generation of carbon dioxide throughout the life of the product and/or that are inexpensive in terms of energy and water and/or use greener solvents and/or have fewer synthetic steps and/or are economical in terms of atoms.

It has now been discovered that the application to the hair of a composition comprising at least one silicate compound and of another composition comprising at least one particular phosphoric compound makes it possible to achieve the objectives set out above, and in particular to repair and/or prevent breakage of said hair, in particular by improving the density of bonds between the proteins present in the cortex of said hair.

The subject of the present invention is notably a process for treating the hair, preferably a cosmetic process, comprising at least the following steps:

(i) a step of applying to the hair a composition (A) comprising at least one silicate compound,

(ii) a step of applying to the hair a composition (B), different from composition (A), comprising at least one phosphoric compound of formula (I) below, and/or at least one salt thereof:

R-[O-P(O)(OH)₂]_n (I) in which R represents a linear or branched, cyclic or non-cyclic, alkyl or alkylene radical comprising from 1 to 12 carbon atoms, and n represents an integer between 1 and 10, and

(iii) a step of applying to the hair a composition (C), different from compositions (A) and (B), comprising at least one alkali metal salt and/or at least one alkaline-earth metal salt; wherein step (iii) of applying composition (C) to the hair is performed before the application steps (i) and (ii). It has been found that the treatment process according to the invention enables the hair, preferably damaged and/or sensitized hair, to be repaired and/or prevented from breaking. Specifically, the process of the invention increases the density of bonds between the proteins present in the cortex of said hair. Said hair is then more resistant to external stresses, notably with regard to dyeing, bleaching, combing and/or disentangling.

These properties are also persistent after several shampoo washes. Hair treated by means of the process of the invention is repaired and/or protected in a lasting manner against external agents and/or against treatments that are liable to impair said hair.

A subject of the invention is also the use of composition (A), composition (B) and composition (C), for repairing and/or preventing hair breakage.

Other subjects, characteristics, aspects and advantages of the invention will emerge even more clearly on reading the description and the example that follows.

In the present description, and unless otherwise indicated:

- the term “at least one” is equivalent to the term “one or more” and can be replaced therewith;

- the term “between... and...” is equivalent to the term “ranging from... to...” and can be replaced therewith, and implies that the limits are included;

- for the purposes of the present invention, the term “greater than” and, respectively, the term “less than” refer to an open range which is strictly greater, or, respectively, strictly less, and thus that the limits are not included;

- according to the present patent application, the term “keratin fibres” particularly means human keratin fibres such as head hair, eyelashes, eyebrows, and bodily hair, preferentially head hair, eyebrows and eyelashes, even more preferentially head hair;

- for the purposes of the present invention, the term “the hair" means head hair. This term does not correspond to bodily hairs, the eyebrows or the eyelashes.

Composition (A):

The process according to the invention comprises step (i) of applying to the hair a composition (A), preferably a cosmetic composition, comprising at least one silicate compound. For the purposes of the present invention, the term “silicate compound” means a silicic acid salt.

Preferably, composition (A) comprises at least one water-soluble silicate.

For the purposes of the present invention, the term “water-soluble silicate” means a silicate which has a solubility in water at ordinary room temperature (25°C) and at atmospheric pressure (1.013 x 10⁵ Pa) of greater than 0.5% by weight (in grams of water-soluble silicate per 100 ml of water), preferably greater than 1% by weight (in grams of water-soluble silicate per 100 ml of water).

More preferentially, the silicate(s) are chosen from alkali metal silicates, alkaline-earth metal silicates and mixtures thereof.

Even more preferentially, the silicate(s) are chosen from sodium silicates, potassium silicates, magnesium silicates, calcium silicates, and mixtures thereof.

Better still, the silicate(s) are chosen from sodium silicates, potassium silicates and mixtures thereof.

Even better still, composition (A) comprises at least one sodium silicate.

Most particularly preferably, composition (A) comprises at least sodium metasilicate.

Preferably, the total content of silicate compound(s) in composition (A) ranges from 0.01% to 20% by weight, more preferentially from 0.05% to 15% by weight, even more preferentially from 0.1% to 15% by weight, better still from 0.5% to 10% by weight, better still from 0.75% to 5% by weight and even better still from 1% to 5% by weight, relative to the total weight of composition (A).

Preferably, the total content of sodium silicate(s) in composition (A) ranges from 0.01% to 20% by weight, more preferentially from 0.05% to 15% by weight, even more preferentially from 0.1% to 15% by weight, better still from 0.5% to 10% by weight, better still from 0.75% to 5% by weight and ever better still from 1% to 5% by weight, relative to the total weight of composition (A).

Preferably, the total content of sodium metasilicate in composition (A) ranges from 0.01% to 20% by weight, more preferentially from 0.05% to 15% by weight, even more preferentially from 0.1% to 15% by weight, better still from 0.5% to 10% by weight, better still from 0.75% to 5% by weight and ever better still from 1% to 5% by weight, relative to the total weight of composition (A). More preferentially, the total content of water in composition (A) ranges from 80% to 99.99% by weight, more preferentially from 85% to 99.95% by weight, even more preferentially from 85% to 99.90% by weight, better still from 90% to 99.50% by weight, better still from 95% to 99.25% by weight and even better still from 95% to 99% by weight, relative to the total weight of composition (A).

The pH of composition (A) according to the invention preferably ranges from 7 to 14, more preferentially from 7.5 to 13.5, more preferentially from 8 to 13.2, better still from 9 to 13 and even better still from 10 to 12.

The pH of composition (A) may be adjusted to the desired value by means of basifying agents or acidifying agents that are customarily used. Among the basifying agents, examples that may be mentioned include aqueous ammonia, alkanolamines, and mineral or organic hydroxides. Among the acidifying agents, examples that may be mentioned include mineral or organic acids, for instance hydrochloric acid, orthophosphoric acid, sulfuric acid, carboxylic acids, for instance acetic acid, tartaric acid, citric acid or lactic acid, and sulfonic acids.

Preferably, composition (A) does not contain a phosphoric compound of formula (I) as described hereinbelow and/or a salt thereof.

Composition (B):

The process according to the invention comprises step (ii) of applying to the hair a composition (B) comprising at least one phosphoric compound of formula (I) below, and/or at least one salt thereof:

R-[O-P(O)(OH)₂]_n (I) in which R represents a linear or branched, cyclic or non-cyclic, alkyl or alkylene radical comprising from 1 to 12 carbon atoms, and n represents an integer between 1 and 10.

The composition (B) is different from composition (A) as described previously.

For the purposes of the present invention, the term “alkyl radical” means a saturated, linear or branched, cyclic or non-cyclic, hydrocarbon-based group comprising from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, more preferentially from 4 to 8 carbon atoms, even more preferentially from 5 to 7 carbon atoms, such as 6 carbon atoms.

For the purposes of the present invention, the term “alkylene radical” means a divalent, linear or branched, cyclic or non-cyclic, hydrocarbon-based group comprising from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, more preferentially from 4 to 8 carbon atoms, even more preferentially from 5 to 7 carbon atoms.

Preferably, n is an integer between 4 and 8, preferably between 5 and 7. More preferentially, n is equal to 6.

Preferably, R represents a linear or branched, cyclic or non-cyclic alkyl radical comprising:

- from 1 to 12 carbon atoms, more preferentially from 1 to 10 carbon atoms, even more preferentially from 4 to 8 carbon atoms, better still from 5 to 7 carbon atoms; and

- n represents an integer between 1 and 10, more preferentially between 4 and 8, even more preferentially between 5 and 7, and better still n is equal to 6.

More preferentially, R represents a linear or branched, cyclic alkyl radical comprising:

- from 1 to 12 carbon atoms, more preferentially from 1 to 10 carbon atoms, even more preferentially from 4 to 8 carbon atoms, better still from 5 to 7 carbon atoms, such as 6 carbon atoms; and

Even more preferentially, R represents a cyclic alkyl radical comprising:

Better still, R represents a cycloalkyl radical, comprising: - from 4 to 8 carbon atoms, better still from 5 to 7 carbon atoms such as 6 carbon atoms; and

Advantageously, R represents a cyclohexyl radical.

Most particularly preferably, the phosphoric compound of formula (I) is phytic acid. By way of example of a commercial phytic acid, mention may be made of the compound sold by the company Tsuno Rice Fine Chemicals under the name “Phytic acid and water”.

Advantageously, the salts of the phosphoric compounds of formula (I) are chosen from alkali metal salts; preferably from the sodium salts and potassium salts. More preferentially, the salts of the phosphoric compounds of formula (I) are sodium salts.

For the purposes of the present invention, the phosphoric compounds of formula (I) and the salts thereof are different from the silicate compounds according to the invention.

Preferably, the total content of phosphoric compound(s) of formula (I) and/or salts thereof in composition (B) is in the range from 0.01% to 20% by weight, more preferentially from 0.05% to 15% by weight, even more preferentially from 0.1% to 15% by weight, better still from 0.5% to 10% by weight, even better still from 0.75% to 5% by weight, better still from 1% to 5% by weight, relative to the total weight of composition (B).

Preferably, the total content of phytic acid and/or salts thereof in composition (B) is in the range from 0.01% to 20% by weight, more preferentially from 0.05% to 15% by weight, even more preferentially from 0.1% to 15% by weight, better still from 0.5% to 10% by weight, even better still from 0.75% to 5% by weight, better still from 1% to 5% by weight, relative to the total weight of composition (B).

Composition (B) is preferably aqueous.

More preferentially, the total content of water in composition (B) ranges from 80% to 99.99% by weight, more preferentially from 85% to 99.95% by weight, even more preferentially from 85% to 99.90% by weight, better still from 90% to 99.50% by weight, better still from 95% to 99.25% by weight and even better still from 95% to 99% by weight, relative to the total weight of composition (B).

The pH of composition (B) according to the invention preferably ranges from 1.5 to 7, more preferentially from 1.5 to 6, more preferentially from 1.5 to 5, better still from 1.5 to 4.

The pH of composition (B) may be adjusted to the desired value by means of the basifying agents or acidifying agents such as those described previously for composition (A).

Preferably, composition (B) does not contain any silicate compound as described above.

Composition (Q:

The process according to the invention comprises a step (iii) of applying to the hair a composition (C) comprising at least one alkali metal salt and/or at least one alkaline-earth metal salt.

Composition (C) is different from compositions (A) and (B) as described previously.

For the purposes of the present invention, the alkali metal and/or alkaline- earth metal salt(s) present in composition (C) are different from the silicate compound(s) present in composition (A) and, when they are present in composition

(B), from the salt(s) of phosphoric compounds of formula (I).

Advantageously, composition (C) does not contain a silicate compound and does not contain a phosphoric compound of formula (I) or a salt thereof.

Preferably, the alkali metal and/or alkaline-earth metal salt(s) of composition

(C) are chosen from the calcium salts, magnesium salts, sodium salts, potassium salts, and mixtures thereof.

More preferentially, the alkali metal and/or alkaline-earth metal salt(s) of composition (C) are calcium salts. Even more preferentially, the alkali metal and/or alkaline-earth metal salt(s) of composition (C) are chosen from calcium hydroxide, calcium oxides, calcium halides, calcium nitrate, calcium hydrogen carbonate, and mixtures thereof.

Most particularly preferably, the alkali metal or alkaline-earth metal salt(s) of composition (C) are chosen from calcium halides, such as calcium chloride.

According to a particular embodiment of the invention, composition (C) comprises:

* at least one calcium salt, and

* at least one alkali metal salt and/or at least one additional alkaline-earth metal salt, other than calcium salts.

Preferably, the total content of alkali metal and/or alkaline-earth metal salt(s) in composition (C) ranges from 0.1% to 40% by weight, more preferentially from 0.5% to 30% by weight, even more preferentially from 1% to 25% by weight, better still from 2% to 20% by weight, even better still from 5% to 15% by weight, relative to the total weight of composition (C).

Preferably, the total content of calcium halide(s) in composition (C) ranges from 0.1% to 40% by weight, more preferentially from 0.5% to 30% by weight, even more preferentially from 1% to 25% by weight, better still from 2% to 20% by weight, even better still from 5% to 15% by weight, such as 10% by weight, relative to the total weight of composition (C).

Preferably, the total content of calcium chloride in composition (C) ranges from 0.1% to 40% by weight, more preferentially from 0.5% to 30% by weight, even more preferentially from 1% to 25% by weight, better still from 2% to 20% by weight, even better still from 5% to 5% by weight, such as 10% by weight, relative to the total weight of composition (C).

More preferentially, the total content of water in composition (C) ranges from 60% to 99.9% by weight, more preferentially from 70% to 99.5% by weight, even more preferentially from 75% to 99% by weight, better still from 80% to 98% by weight, even better still from 85% to 95% by weight, relative to the total weight of composition (C). The pH of composition (C) according to the invention preferably ranges from 7 to 12, more preferentially from 7.5 to 11.5 and even more preferentially from 8 to 11.

The pH of composition (C) may be adjusted to the desired value by means of the basifying agents or acidifying agents such as those described previously for composition (A).

Composition A and/or composition B and/or composition C according to the invention may also contain any adjuvant or additive usually used in cosmetic compositions for treating the hair.

Among the additives that may be contained in the composition, mention may be made of softeners, antifoams, moisturizers, mineral fillers, UV-screening agents, peptizers, fragrances, anionic, cationic, nonionic or amphoteric surfactants, proteins, vitamins, anionic, cationic, nonionic or amphoteric polymers, preserving agents, rheological agents, silicones, and mixtures thereof.

Compositions A, B and C may notably be in the form of a suspension, a dispersion, a gel, an emulsion, notably an oil-in-water (O/W) or water-in-oil (W/O) emulsion, or a multiple emulsion (W/O/W or polyol/O/W or O/W/O), in the form of a cream, a mousse, a milk, a dispersion of vesicles, notably of ionic or nonionic lipids, or a two-phase or multi-phase lotion.

The treatment process

The treatment process, preferably a cosmetic process, according to the invention is a hair treatment process.

Preferably, the treatment process according to the present invention is a process for repairing and/or preventing hair breakage.

According to the invention, steps (i), (ii) and (iii) are different and are performed sequentially.

Preferably, step (i) of applying composition (A) to the hair is performed before step (ii) of applying composition (B) to the hair. According to the invention, step (iii) of applying composition (C) to the hair is performed before the application steps (i) and (ii).

Preferably, step (iii) of applying composition (C) to the hair is performed first, followed by step (i) of applying composition (A), and finally step (ii) of applying composition (B).

The treatment process according to the invention may be applied to dry or damp hair, preferably to damp hair.

The bath ratio of composition (A), (B) and/or (C) applied to the hair may advantageously range from 0.1 to 10, preferably from 0.5 to 5, more preferentially from 0.8 to 2. The term “bath ratio” means the ratio between the total weight of the applied composition and the total weight of hair to be treated.

The treatment process according to the invention may optionally also comprise at least one additional step chosen from steps iv) to vi) below: iv) a step of leaving composition (A), (B) and/or (C) on the hair, advantageously on wet hair, preferably for a period of at least 10 seconds, said leave- on step optionally being performed under an airtight film such as a curlpaper or a plastic film; v) a step of rinsing and/or washing the hair; vi) a step of drying the hair in ambient air or using a heating device.

Said leave-on step may have a duration ranging from 10 seconds to 60 minutes, preferably from 30 seconds to 50 minutes, more preferentially from 5 minutes to 45 minutes.

The washing step may be performed, for example, using a shampoo.

The temperature of said heating device in the drying step may range from 45°C to 230°C, preferably from 45°C to 100°C, more preferentially from 50°C to 80°C. A hairdryer, a heating hood, an iron or a heating brush may be used, for example, as heating device.

The drying step vi) may also be a combination of drying with air or with a heating device at a temperature ranging from 50°C to 80°C, such as a hairdryer or a heating hood, followed by an ironing step, preferably with a straightening iron.

Steps iv), v) and/or vi) may be performed before or after each step i), ii) and/or iii) according to the invention. Steps i) to iii) or steps i) to vi) may be spaced from one step to the next by a few minutes to a few days or weeks; there is preferably less than one hour between each step of the process according to the invention.

According to a preferred embodiment, the process according to the invention comprises the sequential application of composition (A) followed by a leave-on time, followed by the application of composition (B), followed by a leave-on time, the application of composition (A) being preceded by the application of a composition (C) that is left on.

Preferably, the process according to the invention comprises a single washing step performed on conclusion of steps i) and ii) and iii).

Preferably, the hair treated via the process of the invention is damaged and/or sensitized hair.

For the purposes of the present invention, the term “damaged hair” means hair that is dry, rough, brittle, split and/or limp.

For the purposes of the present invention, the term “sensitized hair” means hair that has been bleached, artificially dyed, relaxed and/or permed.

The present invention also relates to the use of composition (A), composition (B) and composition (C), as described previously, for repairing and/or preventing hair breakage.

The examples that follow serve to illustrate the invention without, however, being limiting in nature.

Examples

Example 1: a. Preparation o f the compositions '.

Compositions A, B and C were prepared from the ingredients indicated in the table below, the amounts of which are expressed as weight percentages of active material (AM):

[Table 1] b. Preparation of the locks of hair:

Locks of HT4 Caucasian hair, weighing 1 g and measuring 20 cm in length, are sensitized by a treatment consisting in applying to the locks a mixture of a BlondStudio® 6 persulfate-based bleaching powder from L’Oreal Professionnel with a 40 vol. aqueous hydrogen peroxide-based oxidizing composition in a mass ratio of 4:6, in a bath ratio of 10 g of BlondStudio® 6/H2O2 mixture per gram of hair, at 33°C. After a leave-on time of the bleaching mixture of 50 minutes, the locks of hair are wrung dry between the fingers, and then washed with shampoo. c. Application protocols:

* Two-step process Pl - A+B (comparative '.

Composition A is applied to a lock of wet hair which has been bleached beforehand (see paragraph b. above), in a bath ratio of 1 g of composition A per gram of hair and at 33 °C. After a leave-on time of 30 minutes, the lock is wrung dry between the fingers, and composition B is then applied to the same lock of hair, which is still damp, in a bath ratio of 1 g of composition B per gram of hair and at 33°C.

After a leave-on time of 30 minutes, the lock is wrung dry between the fingers, then washed with shampoo and finally dried with a hairdryer.

* Three-step process P2 - C+A+B (invention)'.

Composition C is first applied to a lock of wet hair that has been bleached beforehand (see paragraph b. above), in a bath ratio of 1 g of composition C per gram of hair and at 33°C.

After a leave-on time of 30 minutes, the lock is wrung dry between the fingers, and composition A is then applied to the same lock of hair, which is still damp, in a bath ratio of 1 g of composition A per gram of hair and at 33°C.

After a leave-on time of 30 minutes, the lock is wrung dry between the fingers, and composition B is then applied to the same lock of hair, which is still damp, in a bath ratio of 1 g of composition B per gram of hair and at 33°C.

A natural, non-sensitized lock of HT4 Caucasian hair weighing 1 g and measuring 20 cm in length and a lock of HT4 Caucasian hair weighing 1 g and measuring 20 cm in length sensitized in accordance with preparation b. above without any other treatment (i.e. not treated using protocols Pl or P2) were used as references. d. Study of hair fibre repair by differential scanning calorimetry

The differential scanning calorimetry technique is known to those skilled in the art as a method for quantifying the strengthening of proteins in the cortex of keratin fibres (Kinetics of the changes imparted to the main structural components of human hair by thermal treatment, https://doi.Org/10.1016/j.tca.2018.01.014 & F.-J. Wortmann and H. Deutz, J. Appl. Polym. Sci., 48, 137 (1993)). The principle of the test is to measure the protein denaturing temperature. It is widely acknowledged that the higher the protein denaturing temperature, the better the integrity of the proteins of the cortex, which reflects the reduction in fibre breakage. The denaturing temperature is directly linked to the bonding density of the keratin proteins present in the cortex. Thus, the lower the denaturing temperature, the lower the bonding density between the proteins: the disulfide bridges break and the cortex is damaged. A difference of 2°C is acknowledged by those skilled in the art as a significant modification.

The apparatus used for performing the measurements is a Mettler DSC 3+ reference machine (temperature range: 30°C-250°C; heating ramp of 10°C/minute). This machine measures the energy flow during heating of the sample. The temperature of maximum energy flow represents the denaturing temperature.

The results of the denaturing temperature measurements for each of the locks are summarized in the table below.

[Table 2]

The above results show that process P2 according to the invention increases the density of bonding of the keratin proteins present in the cortex of the treated hair, thus enabling repair of the sensitized hair.

Specifically, the denaturing temperature of locks treated according to the process P2 of the invention is better than that measured for the non-sensitized hair, thus demonstrating that the hair is repaired.

In addition, the denaturing temperature of locks treated according to the process P2 of the invention is better than that the denaturing temperature of locks treated according to the comparative process Pl . Example 2: a. Preparation o f the compositions '.

Composition D according to the invention was prepared from the ingredients indicated in the table 3 below, the amounts of which are expressed as weight percentages of active material (AM). Compositions A and B correspond to the compositions A and B as used in Example 1.

[Table 3] b. Preparation of the locks of hair:

* Three-step process P3 - D+A+B (invention}'.

Composition D is first applied to a lock of wet hair that has been bleached beforehand (see paragraph b. above), in a bath ratio of 1 g of composition D per gram of hair and at 33°C. After a leave-on time of 30 minutes, the lock is wrung dry between the fingers, and composition A is then applied to the same lock of hair, which is still damp, in a bath ratio of 1 g of composition A per gram of hair and at 33°C.

* Three-step process P4 - A+B+D (comparative .

Composition A is first applied to a lock of wet hair that has been bleached beforehand (see paragraph b. above), in a bath ratio of 1 g of composition A per gram of hair and at 33°C.

After a leave-on time of 30 minutes, the lock is wrung dry between the fingers, and composition D is then applied to the same lock of hair, which is still damp, in a bath ratio of 1 g of composition D per gram of hair and at 33°C.

A natural, non-sensitized lock of HT4 Caucasian hair weighing 1 g and measuring 20 cm in length and a lock of HT4 Caucasian hair weighing 1 g and measuring 20 cm in length sensitized in accordance with preparation b. above without any other treatment (i.e. not treated using protocols P3 or P4) were used as references. d. Study of hair fibre repair by differential scanning calorimetry

The denaturing temperature has been measured for each of the locks according to the method as described in Example 1.

The results are summarized in the table 4 below. [Table 4]

The above results show that process P3 according to the invention increases the density of bonding of the keratin proteins present in the cortex of the treated hair, thus enabling repair of the sensitized hair.

Specifically, the denaturing temperature of locks treated according to the process P3 of the invention is close to that measured for the non-sensitized hair, thus demonstrating that the hair is repaired.

In addition, the denaturing temperature of locks treated according to the process P3 of the invention is better than that the denaturing temperature of locks treated according to the comparative process P4.

Claims

1. Hair treatment process comprising at least the following steps:

(iii) a step of applying to the hair a composition (C), different from compositions (A) and (B), comprising at least one alkali metal salt and/or at least one alkaline-earth metal salt; wherein step (iii) of applying composition (C) to the hair is performed before the application steps (i) and (ii).

2. Process according to the preceding claim, characterized in that the silicate(s) in composition (A) are chosen from alkali metal silicates, alkaline-earth metal silicates and mixtures thereof; preferably from sodium silicates, potassium silicates, magnesium silicates, calcium silicates and mixtures thereof; more preferentially from sodium silicates, potassium silicates and mixtures thereof; even more preferentially sodium silicates.

3. Process according to any one of the preceding claims, characterized in that composition (A) comprises at least sodium metasilicate.

4. Process according to any one of the preceding claims, characterized in that the total content of silicate compound(s) in composition (A) ranges from 0.01% to 20% by weight, preferably from 0.05% to 15% by weight, more preferentially from 0.1% to 15% by weight, even more preferentially from 0.5% to 10% by weight, better still from 0.75% to 5% by weight, and even better still from 1% to 5% by weight, relative to the total weight of composition (A).

5. Process according to any one of the preceding claims, characterized in that, in formula (I) of the phosphoric compounds, R represents a linear or branched, cyclic or non-cyclic, alkyl radical, comprising:

6. Process according to any one of the preceding claims, characterized in that, in formula (I) of the phosphoric compounds, R represents a cyclic alkyl radical, comprising:

- n represents an integer between 1 and 10, more preferentially between 4 and 8, even more preferentially between 5 and 7, and better still n is equal to 6; preferably, R represents a cyclohexyl radical.

7. Process according to any one of the preceding claims, characterized in that composition (B) comprises at least phytic acid.

8. Process according to any one of the preceding claims, characterized in that the total content of phosphoric compound(s) of formula (I) and/or salts thereof in composition (B) is in the range from 0.01% to 20% by weight, preferably from 0.05% to 15% by weight, more preferentially from 0.1% to 15% by weight, even more preferentially from 0.5% to 10% by weight, better still from 0.75% to 5% by weight, and even better still from 1% to 5% by weight, relative to the total weight of composition (B).

9. Process according to any one of the preceding claims, characterized in that step (i) is performed before step (ii).

10. Process according to any one of the preceding claims, characterized in that the alkali metal and/or alkaline-earth metal salt(s) of composition (C) are chosen from the calcium salts, magnesium salts, sodium salts, potassium salts and mixtures thereof; preferably from the calcium salts; more preferentially from calcium hydroxide, calcium oxides, calcium halides, calcium nitrate, calcium hydrogen carbonate, and mixtures thereof; even more preferentially from calcium halides, such as calcium chloride.

11. Process according to any one of the preceding claims, characterized in that the total content of alkali metal and/or alkaline-earth metal salt(s) in composition (C) ranges from 0.1% to 40% by weight, preferably from 0.5% to 30% by weight, more preferentially from 1% to 25% by weight, even more preferentially from 2% to 20% by weight, and better still from 5% to 15% by weight, relative to the total weight of composition (C).

12. Process according to any one of the preceding claims, characterized in that composition (B) is aqueous; preferably, the total content of water in composition (B) ranges from 80% to 99.99% by weight, more preferentially from 85% to 99.95% by weight, even more preferentially from 85% to 99.90% by weight, better still from 90% to 99.50% by weight, better still from 95% to 99.25% by weight and even better still from 95% to 99% by weight, relative to the total weight of composition (B).

13. Process according to any one of the preceding claims, for repairing and/or preventing hair breakage; preferably for repairing and/or preventing the breakage of damaged and/or sensitized hair.