WO2018122123A1

WO2018122123A1 - Process for treating keratin fibres using a derivative of butenedioic acid and an amino silicone

Info

Publication number: WO2018122123A1
Application number: PCT/EP2017/084227
Authority: WO
Inventors: Virginie BURCKBUCHLER
Original assignee: L'oreal
Priority date: 2016-12-29
Filing date: 2017-12-21
Publication date: 2018-07-05
Also published as: FR3061431B1; FR3061431A1

Abstract

The present invention relates to a process for treating keratin fibres, in particular human keratin fibres such as the hair, comprising a first step of applying a composition, comprising a derivative of butenedioic acid and an amino silicone, followed by a second step of heat treatment of the keratin fibres. The present invention also relates to the use of said composition for straightening and/or relaxing keratin fibres, in particular human keratin fibres such as the hair.

Description

Process for treating keratin fibres using a derivative of butenedioic acid and an amino silicone

The present invention relates to a process for treating keratin fibres, in particular human keratin fibres such as the hair, comprising a first step o f applying a composition, comprising a derivative o f butenedioic acid and an amino silicone, followed by a second step o f heat treatment of the keratin fibres .

The present invention also relates to the use o f said composition for straightening and/or relaxing keratin fibres, in particular human keratin fibres such as the hair.

Many people are not satisfied with the appearance of their hair. More particularly, people who have curly hair usually seek to obtain straight hair.

The processes for straightening or relaxing the hair generally invo lve reducing agents based on thio l or strong alkaline agents. These techniques are especially based on cleavage o f the disulfide covalent bonds present in the keratin fibres.

A first technique firstly consists in opening the disulfide bonds by means o f a composition comprising a reducing agent. Then, secondly, said disulfide bonds are re-formed by applying to the hair, which has been rinsed and placed under tension beforehand, for example by means o f ro llers, an oxidizing composition, also referred to as "fixative". This fixing step makes it possible to give the head o f hair the desired shape.

A second technique consists in performing a lanthionization operation, using a composition containing a base belonging to the hydroxide family. Contrary to the first technique, this second technique does not require a fixing step, since the formation o f the lanthionine bonds is irreversible. It thus makes it possible, without preference, to perform waving, relaxing, uncurling or straightening o f the hair. This technique is more particularly used for relaxing naturally frizzy hair.

However, these two techniques have numerous drawbacks . They especially lead to unpleasant odours during their use. Moreover, they give rise to a certain scalp discomfort and a significant degradation of the keratin fibres.

A new technique has recently been developed, which consists in combining a heat treatment step and a step o f applying a composition comprising formaldehyde. This technique is particularly effective for imparting a better appearance to damaged hair and/or for treating long hair and curly hair.

Indeed, at a temperature that may be up to 200°C or more, for example by means of an iron, formaldehyde crosslinks the proteins o f the keratin fibres by reaction on their nucleophilic sites . However, this technique is not ideal, since the use of formaldehyde may prove irritating or even toxic for some consumers .

This is why it is sought to avoid the use of substances such as formaldehyde.

Consequently, there is a real need to provide novel so lutions for straightening and/or relaxing keratin fibres, in particular human keratin fibres such as the hair, which do not require the use o f such substances .

These novel so lutions must especially make it possible to obtain good curl relaxation and good control o f vo lume, which last over time. These so lutions must also respect the integrity o f the hair and the scalp , and in particular not irritate the latter.

Moreover, these novel straightening and/or relaxing so lutions must make it possible to preserve the co lour of the hair, in particular if the hair is co loured, and also the cosmetic qualities thereo f, such as sheen, a smooth feel, and easy disentangling both when wet and dry.

The applicant discovered, surprisingly, that a process for treating keratin fibres, comprising a step of applying a composition comprising a particular derivative o f butenedioic acid and an amino silicone, fo llowed by a second step of heat treatment o f the keratin fibres, made it possible to achieve the aims set out above. A subj ect of the present invention is especially a process for treating keratin fibres, in particular human keratin fibres such as the hair, preferably bleached, comprising the fo llowing steps :

l ) a first step o f applying, to said keratin fibres, a composition comprising :

- one or more compounds chosen from derivatives o f the butenedioic acid o f formula (I) below, and also the addition salts thereo f, optical isomers thereof, geometric isomers thereof, tautomers thereof, and mixtures thereof

in which formula (I) Ri and R₂, which are identical or different, independently from one another represent a hydrogen atom, a linear or branched C i to C i o alkyl group, or a linear or branched

C₂ to C i o alkenyl group, said alkyl or alkenyl groups being :

optionally interrupted by one or more heteroatoms such as O, S and N(R₃), with R₃ representing a hydrogen atom or a linear or branched C i to C₆ alkyl group, and/or

- optionally substituted by one or more radicals chosen from hydroxyl, amino, C i to C₆ mono- or dialkylamino , C i to C₆ alkoxy, and carboxyl radicals; and

- one or more amino silicones;

fo llowed by

2) a second step o f heat treatment of said keratin fibres at a temperature greater than or equal to 100°C .

A step o f mechanical treatment for relaxing the keratin fibres, such as brushing, preferably accompanied by heating from a hairdryer, may be carried out between the first and second step of the process . Another subj ect of the present invention relates to a composition as defined in the first step of the process, said composition being aqueous at acid pH.

Another subj ect of the invention is the use of a composition as defined above for straightening and/or relaxing keratin fibres, in particular human keratin fibres such as the hair.

The process according to the invention makes it possible especially to obtain good curl relaxation and better control o f vo lume . Indeed, the process provides a significant reduction in the vo lume o f the keratin fibres, while respecting the integrity thereof.

The process according to the invention also makes it possible to confer a "serpentine" movement to the keratin fibres, which is characteristic of Brazilian hair straightening processes, without however requiring the use o f irritating and/or aggressive substances such as formaldehyde.

The straightening obtained by the process according to the present invention lasts over time and withstands several shampooing operations .

Finally, the process according to the invention makes it possible to preserve the co lour of the keratin fibres, especially if the latter are coloured. The keratin fibres treated by the process according to the invention have good cosmetic qualities such as sheen, a smooth and pleasant feel, and easy disentangling both when wet and dry. The keratin fibres are also more well-behaved and have a decreased risk o f breakage.

Other subj ects, characteristics, aspects and advantages o f the invention will emerge even more clearly on reading the description and the examples that follow.

In the fo llowing text, and unless otherwise indicated, the limits of a range o f values are included in that range, especially in the expressions "between " and " ranging from ... to

Moreover, the expressions "at least one", "at least two" and "at least" used in the present description are equivalent to the expressions "one or more", "two or more" and "greater than or equal to", respectively. "A lkyl" is intended to mean a saturated, linear or branched hydrocarbon-based group comprising from 1 to 10 carbon atoms, in particular from 1 to 6 carbon atoms and preferably from 1 to 4 carbon atoms.

"A lkenyl" is intended to mean an unsaturated, linear or branched hydrocarbon-based group comprising from 2 to 10 carbon atoms, in particular from 2 to 6 carbon atoms, preferably from 2 to 4 carbon atoms, and comprising from 1 to 6 conjugated or unconjugated unsaturations, preferably 1 to 2 unsaturations.

"A lkoxy " is intended to mean an alkyl-oxy group with the alkyl group as defined above.

"Acids" are intended to mean mineral or organic acids such as the salts o f hydrochloric acid HC1; hydrobromic acid HBr; sulfuric acid H2 S O4 ; (C i -C6)alkylsulfonic acids Alk-S(0)₂OH, such as methylsulfonic acid and ethylsulfonic acid; arylsulfonic acids Ar- S(0)₂OH, with Ar representing an aryl group, in particular phenyl, such as the salts derived from benzenesulfonic acid and toluenesulfonic acid; (poly)(hydroxy)(C i -C6)alkylcarboxylic acids, such as the salts o f citric acid; succinic acid; tartaric acid; lactic acid, (C i -C6)alkoxysulfinic acids Alk-0-S(0)OH, such as the salts o f methoxysulfinic acid and ethoxysulfinic acid; aryloxysulfinic acids, such as the salts o f to lueneoxysulfinic acid and phenoxysulfinic acid; phosphorus-based acids, such as phosphoric acid H3PO4 ; (C i - C₆)alkylcarboxylic acids, such as acetic acid CHB C(0)O H; triflic acid CF3 S O3H and tetrafluoroboric acid HBF₄.

"Anionic counterion" is intended to mean an anion or an anionic group derived from an organic or mineral acid salt which counterbalances the cationic charge of the compound; more particularly, the anionic counterion is chosen from: i) halides such as chloride or bromide; ii) nitrates; iii) sulfonates, including C i -C₆ alkylsulfonates : Alk-S(0)₂0^" such as methylsulfonate or mesylate and ethylsulfonate; iv) arylsulfonates : Ar-S(0)₂0^" such as benzenesulfonate and toluenesulfonate or tosylate; v) citrate; vi) succinate; vii) tartrate; viii) lactate; ix) alkyl sulfates : Alk-0-S(0)0^" such as methyl sulfate and ethyl sulfate; x) aryl sulfates : Ar-0-S(0)0^" such as benzene sulfate and toluene sulfate; xi) alkoxy sulfates : Alk- 0-S(0)₂0^~ such as methoxy sulfate and ethoxy sulfate; xii) aryloxy sulfates: Ar-0-S(0)₂0-, xiii) phosphates 0=Ρ(ΟΗ)₂-0^", 0=P(0 )₂-OH, 0=P(0 )₃, HO-[P(0)(0 )]w-P(0)(0 )2 with w being an integer; xiv) acetate; xv) triflate; and xvi) borates such as tetrafluoroborate, xvii) disulfate (0=)₂S(0^")₂ or SC ^2" and monosulfate HSC ^"; the anionic counterion, derived from an organic or mineral acid salt, ensures the electrical neutrality of the molecule; thus, it is understood that when the anion comprises several anionic charges, then the same anion can serve for the electrical neutrality of several cationic groups in the same molecule or else may serve for the electrical neutrality of several molecules; for example, a compound which contains two cationic charges may contain either two "singly charged" anionic counterions or contains a "doubly charged" anionic counterion such as (0=)₂S(0^")₂ or 0=P(0 )₂-OH.

A) Composition

Compounds of formula (I)

The composition applied in the first step of the process for treating keratin fibres according to the present invention comprises one or more compounds chosen from derivatives of the butenedioic acid of formula (I) as defined above.

Preferably, Ri and R₂, which are identical or different, independently from one another represent a hydrogen atom or a linear or branched Ci to Cio alkyl group, optionally interrupted by one or more heteroatoms, such as O, S and N(R₃).

Advantageously, Ri and R₂, which are identical or different, independently from one another represent a hydrogen atom or a linear or branched Ci to C₆ alkyl group, optionally substituted by one or more carboxyl radicals.

According to one advantageous embodiment of the invention, the diacids of formula (I) are such that Ri and R₂ are identical.

Preferably, Ri and R₂ represent a hydrogen atom.

According to another particular embodiment of the invention, Ri represents a hydrogen atom and R₂ represents a linear or branched Ci to C₆ alkyl group, optionally substituted by a carboxyl group. Preferably, the compound(s) which are derivatives o f butenedioic acid of formula (I) are chosen from maleic acid, citraconic acid, aconitic acid, the geometric isomers thereo f, the addition salts thereo f, and the mixtures thereof.

The addition salts o f the compound of formula (I) present in the composition according to the invention are chosen especially from the addition salts with an acid, such as the hydrochlorides, hydrobromides, sulfates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, phosphates and acetates, and the addition salts with a base such as sodium hydroxide, potassium hydroxide, aqueous ammonia, amines or alkanolamines .

The total amount of the compound(s) of formula (I), present in the composition according to the invention, preferably ranges from 1 to 20% by weight and more preferentially from 5 to 15 % by weight relative to the total weight of the composition.

Amino silicones

The composition applied in the first step of the process for treating keratin fibres according to the present invention also comprises one or more amino silicones .

"Amino silicone" is intended to mean any silicone comprising at least one primary, secondary, tertiary amine function, a quaternary ammonium group, or else at least one imine function =N-R_a, with R_a representing a hydrogen atom or a group chosen from (C i -C₆)alkyl groups, aryl groups such as phenyl, and aryl(C i - C4)alkyl groups such as benzyl.

Preferably, the amino silicone(s) used in the composition according to the present invention comprise in their structure at least 4 silicon atoms.

Throughout the text below, the term "silicone" is intended to denote, in accordance with what is generally accepted, any organosilicon-based polymers or oligomers o f linear or cyclic, branched or crosslinked structure, of variable mo lecular weight, obtained by polymerization and/or polycondensation o f suitably functionalized silanes, and constituted essentially o f a repetition o f main units in which the silicon atoms are linked together via oxygen atoms (siloxane bond -Si-O-Si-), optionally substituted hydrocarbon- based groups being directly linked via a carbon atom to said silicon atoms. The most common hydrocarbon-based groups are alkyl groups, especially Ci-Cio alkyl groups and in particular methyl, haloalkyl groups, in particular fluoroalkyls, the alkyl part of which is Ci-Cio, and aryl groups and in particular phenyl.

The amino silicones used in the composition according to the present invention may be chosen from the families of compounds (a) to (e) below: (a) the compounds corresponding to the following formula (II):

(R¹)a(T)₃-a-Si[OSi(T)₂]„-[OSi(T)b(R¹)2-b]_m-OSi(T)₃-a-(R¹)a (II) in which formula (II)

- T is a hydrogen atom or a phenyl, hydroxyl (-OH), or Ci-Cs alkyl, and preferably methyl, or Ci-Cs alkoxy, preferably methoxy, group,

- a denotes the number 0 or an integer from 1 to 3, and preferably 0,

- b denotes 0 or 1, and in particular 1,

- m and n are integers such that the sum (n + m) can range especially from 1 to 2000 and in particular from 50 to 150, n possibly denoting an integer from 0 to 1999 and especially from 49 to 149, and m possibly denoting an integer from 1 to 2000 and especially from 1 to 10,

- R¹ is a monovalent group of formula

i) -CqH_2qL, wherein q is an integer between 2 and 8 inclusive and L is an optionally quaternized amino group chosen from the groups:

-N(R²)-ALK-N(R²)₂,

-N(R²)₂,

-N⁺(R²)₃ Q ,

-N(R²)-ALK-N⁺(R²)₂ Q ,

in which:

* R², which are identical or different, denote a hydrogen atom, a phenyl group, a benzyl group or a Ci-C₂o alkyl group,

* Q^" represents an anionic counterion enabling the electrical neutrality of the polymer, preferably a halide ion such as, for example, fluoride, chloride, bromide or iodide, and * ALK represents a linear or branched (Ci-C₆) alkylene group, such as ethylene -CH2-CH2-; or else

ii) -C_qH2q-iL', wherein q is an integer between 2 and 8 inclusive and L' is an optionally quaternized imino group chosen from the groups:

=N-ALK-N(R²)₂,

=N-R²,

=N⁺(R²)₂ Q ,

=N-ALK-N⁺(R²)₃ Q

with ALK, R² and Q^" as defined for L.

In particular, the amino silicones corresponding to the definition of formula (II) are chosen from the compounds corresponding to the following formula (III) or (III'):

(ΙΙΓ) in which formulae (III) or (ΙΙΓ) :

• R, R' and R" , which are identical or different, denote a C 1 -C4 alkyl group, preferably CH3 , a C 1 -C4 alkoxy group, preferably methoxy, or OH,

• A represents a linear or branched C3 - C 8 and preferably C3 - C6 alkylene group,

• A' represents an alkylene group -(CR^aR^b)_p-C(R^c)= with p representing an integer between 0 and 5 inclusive, and R^a, R^b, and

R^c, which are identical or different, representing a hydrogen atom or a (C 1 -C4) alkyl group, preferably R^a, R^b, and R^c represent a hydrogen atom,

• m and n, which are identical or different, are integers that are dependent on the mo lecular weight and whose sum is between 1 and

2000.

According to a particular embodiment of the invention, the amino silicone(s) are of formula (III) .

According to another preferred embodiment of the invention, the amino silicone(s) are of formula (III ' ) .

According to one possibility, R, R' and R" , which are identical or different, each represent a C 1 -C4 alkyl or hydroxyl group, A represents a C3 alkylene group or A' represents a -CH₂-CH₂-CH= group, and m and n are such that the weight-average mo lecular weight of the compound is between approximately 5000 and 500 000. The compounds o f this type are named "amodimethicone" in the CTFA dictionary.

According to another possibility, R, R' and R", which are identical or different, each represent a C 1 - C4 alkoxy or hydroxyl group, at least one o f the groups R and R" is an alkoxy group and A represents a C 3 alkylene group or A' represents a -CH₂-CH₂-CH= group . The hydroxyl/alkoxy mo le ratio is preferably between 0.2/ 1 and 0.4/ 1 and advantageously equal to 0.3/ 1 . Moreover, m and n are such that the weight-average mo lecular weight of the compound is between 2000 and 10⁶. More particularly, n is between 0 and 999 and m is between 1 and 1000, the sum of n and m being between 1 and 1 000. In this category of compounds, mention may be made, inter alia, of the product Belsil^®ADM 652 sold by Wacker.

According to another possibility, R and R", which are different, each represent a C1-C4 alkoxy or hydroxyl group, at least one of the groups R and R" being an alkoxy group, R' representing a methyl group and A representing a C3 alkylene group or A' represents a -CH₂- CH₂-CH= group. The hydroxyl/alkoxy mole ratio is preferably between 1/0.8 and 1/1.1 and advantageously is equal to 1/0.95. Moreover, m and n are such that the weight-average molecular weight of the compound is between 2000 and 200 000. More particularly, n is between 0 and 999 and m is between 1 and 1000, the sum of n and m being between 1 and 1000.

More particularly, mention may be made of the product FluidWR^® 1300 sold by Wacker.

It should be noted that the molecular weight of these silicones is determined by gel permeation chromatography (room temperature, polystyrene standard, μ styragem columns, eluent THF, flow rate of 1 mm/m, 200 μΐ of a solution containing 0.5% by weight of silicone in THF are injected, and detection is performed by refractometry and UV-metry).

A product corresponding to the definition of formula (II) is in particular the polymer known in the CTFA dictionary as "trimethylsilyl amodimethicone", corresponding to formula (IV) below:

ChL CH,

(CH₃)₃ SiO -SiO - SiO— -Si(CH₃3)/3.

I I

ChL CH,

I

CHChL

I

CH,

I

NH

(CH₂)₂

NH₀

m (IV) in which formula (IV) n and m have the meanings given above in accordance with formula (II).

Such compounds are described, for example, in EP 95238. A compound of formula (II) is sold, for example, under the name Q2- 8220 by OSI.

(b) the compounds corresponding to the following formula (V):

in which formula (V)

- R³ represents a monovalent C1-C18 hydrocarbon-based group, and in particular a C1-C18 alkyl or C2-C18 alkenyl group, for example methyl, - R⁴ represents a divalent hydrocarbon-based group, especially a Ci- Ci8 alkylene group or a divalent C1-C18, for example Ci-Cs, alkyleneoxy group,

- Q^" is an anionic counterion, in particular a halide ion, especially chloride, - r represents a mean statistical value from 2 to 20 and in particular from 2 to 8,

- s represents a mean statistical value from 20 to 200 and in particular from 20 to 50.

Such compounds are described more particularly in patent US 4 185087.

A compound falling within this class is the product sold by Union Carbide under the name Ucar Silicone ALE 56.

(c) the quaternary ammonium silicones especially of formula

(VI):

in which formula (VI)

- R₇, which are identical or different, represent a monovalent hydrocarbon-based group having from 1 to 18 carbon atoms, and in particular a Ci-Cis alkyl group, a C2-C18 alkenyl group or a ring comprising 5 or 6 carbon atoms, for example methyl,

- R₆ represents a divalent hydrocarbon-based group, especially a Ci- Ci8 alkylene group or a divalent C1-C18, for example Ci-Cs, alkyleneoxy group linked to the Si via an Si-C bond,

- R-8, which are identical or different, each represent a hydrogen atom, a monovalent hydrocarbon-based group having from 1 to 18 carbon atoms, and in particular a C1-C18 alkyl group, a C2-C18 alkenyl group or an -R₆-NHCOR₇ group,

- X^" is an anionic counterion such as a halide ion, especially chloride or an organic acid salt (acetate, etc.),

- r represents a mean statistical value from 2 to 200 and in particular from 5 to 100.

These silicones are described, for example, in patent application EP-A 0530974. (d) the amino silicones of formula (VII) or (VIF):

H₂N-(C_mH_2m)-N-(C_nH_2n)-Si O R_c

(VII)

H₂N-(C_mH_2m)-N = (C_nH_2n.1)-Si O R_c

(VIF) in which formulae (VII) and (VIF):

- Ri, R₂, R3 and R₄, which are identical or different, each denote a Ci- C₄ alkyl group or a phenyl group,

- R5 denotes a Ci-C₄ alkyl group or a hydroxyl group,

- n is an integer ranging from 1 to 5,

- m is an integer ranging from 1 to 5, and

- x is chosen such that the amine number is between 0.01 and 1 meq/g.

According to a particular embodiment of the invention, the amino silicone(s) are of formula (VII).

According to another particular embodiment of the invention, the amino silicone(s) are of formula (VIF).

and

(e) mixtures thereof.

When these compounds are used, a particularly advantageous embodiment is the use thereof together with surfactants chosen from cationic surfactants, nonionic surfactants and mixtures thereof; and preferably cationic surfactants.

In other words, according to this particular embodiment, the composition applied in the first step of the process for treating keratin fibres according to the present invention also comprises one or more surfactants chosen from cationic surfactants, nonionic surfactants, and mixtures thereof; and preferably cationic surfactants. By way of example, use may be made of the product sold under the name Cationic Emulsion DC939 by Dow Corning, which comprises, besides amodimethicone, a cationic surfactant, namely trimethylcetylammonium chloride, and a nonionic surfactant of formula Ci3H27-(OC2H4)i2-OH, known under the CTFA name Trideceth-12.

Another commercial product that may be used according to the invention is the product sold under the name Dow Corning Q27224 by Dow Corning, comprising, in combination, the trimethylsilyl amodimethicone of formula (IV) described above, a nonionic surfactant of formula: C8Hi7-C6H4-(OCH2CH2)40-OH, known under the CTFA name Octoxynol-40, a second nonionic surfactant of formula: Ci2H25-(OCH2-CH2)6-OH, known under the CTFA name Isolaureth-6, and propylene glycol.

Another commercial product that may be used according to the invention is the product sold under the name Wacker-Belsil ADM LOG 1 by Wacker, comprising, in microemulsion form, an amodimethicone of formula (III) in combination with Trideceth-5 and Trideceth-10.

It is also possible to use the product sold under the trade name Xiameter MEM 8299 emulsion by Dow Corning.

Other amino silicones may be used within the context of the invention, such as the product which is referenced in the CTFA dictionary under the name Polysilicone-9.

Preferably, the amino silicone(s) are chosen from (i) polydi(Ci- Ce)alkylsiloxanes, in particular polydimethylsiloxanes, containing amino(Ci-C6)alkylamino(Ci-C6)alkyl group(s) and/or amino(Ci- C6)alkylimino(Ci-C6)alkyl group(s), preferably polydimethylsiloxane containing aminoethyliminopropyl and/or aminoethylaminopropyl groups, in particular in cationic emulsion;

(ii) polydi(Ci-C6)alkylsiloxanes, in particular polydimethylsiloxane containing amino(Ci-C6)alkylamino(Ci-C6)alkyl group(s) and/or amino(Ci-C6)alkylimino(Ci-C6)alkyl group(s), preferably polydimethylsiloxane containing aminoethyliminopropyl and/or aminoethylaminopropyl group(s) and containing (Ci-C₆)alkoxy group(s) such as methoxy, and/or containing hydroxyl group(s) and a- ω-silanols, preferably in cationic aqueous emulsion, in particular in cationic emulsion; preferably polydimethylsiloxane containing aminoethylaminopropyl group(s), containing methoxy and/or hydroxyl group(s) and α-ω-silanols in cationic aqueous emulsion; and polydimethylsiloxane containing aminoethyliminopropyl group(s) in nonionic microemulsion (at 17%) protected (to 1%) by phenoxyethanol; and

(iii) mixtures of amodimethicone (amino silicone) and surfactants, in particular nonionic or cationic, preferably chosen from poly(Ci- C₆)alkoxylated, preferably polyethoxylated, alcohols, and aliphatic- chain ammoniums RR'R"R"'N⁺, X^" with X^" representing an anionic counterion, in particular halide, and R, R', R", which are identical or different, represent a (Ci-C₆)alkyl group, R'" represents a (Cio- C3o)alkyl group, such as the following combinations:

- amodimethicone and trideceth-5, and trideceth-10 for example those sold under the name DC(R)2-2899 by Dow Corning;

- amodimethicone and trideceth-6, and cetrimonium salts, for example those sold under the name Belsil ADM by Wacker;

- amodimethicone and trideceth-12, and cetrimonium salts.

Preferably, the amino silicone(s) are chosen from poly(di)(Ci- Ce)alkylsiloxanes containing imino(Ci-Ce)alkyl groups or containing (di)(Ci-C6)(alkyl)amino(Ci-C6)alkylimino(Ci-C6)alkyl groups; more preferentially from polydi(Ci-C4)alkylsiloxanes containing imino(Ci- C₄)alkyl groups or containing (di)(Ci-C₄)(alkyl)amino(Ci- C₄)alkylimino(Ci-C₄)alkyl groups and better still from polydimethylsiloxanes containing imino(Ci-C₄)alkyl groups or containing amino(Ci-C3)alkylimino(Ci-C₄)alkyl groups such as polydimethylsiloxanes containing iminopropyl or aminoethyliminopropyl groups.

The total amount of the amino silicone(s) present in the composition according to the invention preferably ranges from 0.5 to 20% by weight, more preferentially from 1 to 10% by weight, and better still from 2 to 5% by weight, relative to the total weight of the composition.

Preferably, the weight ratio between the total amount of the compound(s) of formula (I) and the total amount of the amino silicone(s), present in the composition according to the invention, ranges from 0. 1 to 10, more preferentially from 0.5 to 5 , better still from 1 to 4 , and more particularly from 1 .5 to 3 , such as 2.8.

A lkaline agents

The composition applied in the first step of the process for treating keratin fibres according to the present invention may optionally also comprise one or more alkaline agents.

According to a particular embodiment, the composition according to the invention also comprises one or more alkaline agents.

The alkaline agent(s) may be chosen especially from mineral, organic or hybrid alkaline agents, and mixtures thereof.

The mineral alkaline agent(s) are preferably chosen from aqueous ammonia, alkali metal carbonates or bicarbonates such as sodium carbonate or bicarbonate, potassium carbonate or bicarbonate, sodium hydroxide or potassium hydroxide or mixtures thereof.

The organic alkaline agent(s) are preferably chosen from organic amines with a pKb at 25 °C o f less than 12, preferably o f less than 10 and more advantageously still of less than 6. It should be noted that this is the pKb corresponding to the function having the highest basicity. In addition, the organic amines do not comprise any alkyl or alkenyl fatty chain comprising more than ten carbon atoms .

The organic alkaline agent(s) are preferably chosen from alkano lamines, in particular mono-, di- or tri- hydroxy(C i - C6)alkylamine, such as triethano lamine, oxyethylenated and/or oxypropylenated ethylenediamines, amino acids, the polyamines o f formula (VIII) below, and mixtures thereof:

in which formula (VIII) W is a divalent C i to C₆ alkylene radical optionally substituted with one or more hydroxyl groups or a C i to C₆ alkyl radical, and/or optionally interrupted with one or more heteroatoms such as O, or NR_U; R_x, R_y, Rz, Rt, and R_u, which are identical or different, represent a hydrogen atom, a C i to C₆ alkyl or C i to C₆ hydroxyalkyl or C i to C₆ amino alkyl radical. Examples of amines of formula (VIII) that may be mentioned include 1 ,3-diaminopropane, 1 ,3-diamino-2-propanol, spermine and spermidine.

The term "alkanolamine" means an organic amine comprising a primary, secondary or tertiary amine function, and one or more linear or branched Ci to Cs alkyl groups bearing one or more hydroxyl radicals.

Organic amines chosen from alkanolamines such as monoalkanolamines, dialkanolamines or trialkanolamines comprising one to three identical or different Ci to C₄ hydroxyalkyl radicals are in particular suitable for carrying out the invention.

Among the compounds of this type, mention may be made 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 and tris(hydroxymethyl)amino methane.

More particularly, the amino acids that may be used are of natural or synthetic origin, in their L, D or racemic form, and comprise at least one acid function chosen more particularly from carboxylic acid, sulfonic acid, phosphonic acid and phosphoric acid functions. The amino acids may be in neutral or ionic form.

As amino acids that may be used in the present invention, mention may especially be made of aspartic acid, glutamic acid, alanine, arginine, ornithine, citrulline, asparagine, carnitine, cysteine, glutamine, glycine, histidine, lysine, isoleucine, leucine, methionine, N-phenylalanine, proline, serine, taurine, threonine, tryptophan, tyrosine and valine.

Advantageously, the amino acids are basic amino acids comprising an additional amine function optionally included in a ring or in a ureido function.

Such basic amino acids are preferably chosen from those corresponding to formula (IX) below, and also the salts thereof

R-CH₂-CH(NH₂)-C(0)-OH (IX) in which formula (IX) R represents a group chosen from imidazolyl, preferably imidazolyl-4-yl; aminopropyl; aminoethyl;

-(CH₂)₂N(H)-C(0)-NH₂; and -(CH₂)₂-N(H)-C(NH)-NH₂.

The compounds corresponding to formula (IX) are histidine, lysine, arginine, ornithine and citrulline.

The organic amine may also be chosen from organic amines of heterocyclic type. Besides histidine that has already been mentioned in the amino acids, mention may in particular be made of pyridine, piperidine, imidazole, triazole, tetrazole and benzimidazole.

The organic amine may also be chosen from amino acid dipeptides. As amino acid dipeptides that may be used in the present invention, mention may be made especially of carnosine, anserine and balenine.

The organic amine may also be chosen from compounds comprising a guanidine function. As amines of this type that may be used in the present invention, besides arginine, which has already been mentioned as an amino acid, mention may especially be made of creatine, creatinine, 1 , 1 -dimethylguanidine, 1 , 1 -diethylguanidine, glycocyamine, metformin, agmatine, n-amidinoalanine, 3- guanidinopropionic acid, 4-guanidinobutyric acid and 2- ([ amino (imino)methyl] amino) ethane- 1 - sulfonic acid.

Hybrid compounds that may be mentioned include the salts of the amines mentioned previously with acids such as carbonic acid or hydrochloric acid.

Guanidine carbonate or monoethanolamine hydrochloride may be used in particular.

Preferably, the alkaline agent(s) present in the composition according to the invention are chosen from aqueous ammonia, alkanolamines, amino acids in neutral or ionic form, in particular basic amino acids, and preferably corresponding to those of formula (IX).

More preferentially, the alkaline agent(s) present in the composition according to the invention are chosen from aqueous ammonia, alkanolamines and mixtures thereof, and better still from aqueous ammonia, mono-, di- or tri- hydroxy(Ci-C6)alkylamines, such as triethanolamine, and mixtures thereof. The total amount o f the alkaline agent(s), when it(they) is(are) present in the composition according to the invention, preferably ranges from 0.5 to 1 0% by weight, more preferentially from 1 to 7% by weight, and better still from 3 to 6% by weight, relative to the total weight o f the composition.

Preferably, the weight ratio between the total amount of the compound(s) o f formula (I) and the total amount o f the alkaline agent(s), when they are present in the composition according to the invention, ranges from 1 to 5 , more preferentially from 1 .5 to 3 , and better still from 1 .5 to 2.5.

The pH of the composition applied in the first step of the process for treating keratin fibres according to the present invention preferably ranges from 0.5 to 5 , more preferentially from 1 to 4, and better still from 1 to 1 .5. It may be adjusted to the desired value by means o f acidifying or alkaline agents usually used in the treatment of keratin fibres, or else using standard buffer systems .

Among the acidifying agents, mention may be made, for example, o f mineral or organic acids, such as hydrochloric acid, orthophosphoric acid, sulfuric acid, carboxylic acids, such as acetic acid, tartaric acid, citric acid or lactic acid, and sulfonic acids.

The alkaline agents are such as those defined previously.

According to a particular embodiment, the composition applied in the first step of the process according to the invention comprises : one or more compounds chosen from derivatives of the butenedio ic acid o f formula (I), as defined above, and also the addition salts thereo f, optical isomers thereof, geometric isomers thereo f, tautomers thereof, and mixtures thereof,

one or more amino silicones, as defined above, and

one or more alkaline agents;

said alkaline agents being in an amount such that the pH o f said composition ranges from 0.5 to 5 , more preferentially from 1 to 4 , and better still from 1 to 1 .5.

Solvents

The composition applied in the first step of the process for treating keratin fibres according to the present invention may optionally also comprise water, an organic so lvent, or mixtures thereo f.

Examples o f organic so lvents that may be mentioned include linear or branched C₂ to C₄ alkano ls, such as ethanol and isopropano l; glycerol; polyo ls and polyol ethers, for instance 2-butoxyethanol, propylene glyco l, hexylene glyco l, dipropylene glyco l, propylene glyco l monomethyl ether, diethylene glyco l monomethyl ether and monoethyl ether, and also aromatic alcohols or ethers, such as benzyl alcoho l or phenoxyethanol, and mixtures thereof.

Non-silicone fatty substances

The composition applied in the first step of the process for treating keratin fibres according to the present invention may optionally also comprise one or more non-silicone fatty substances .

The term "fatty substance" means an organic compound that is inso luble in water at ordinary room temperature (25 °C) and at atmospheric pressure (760 mmHg), with a so lubility in water of less than 5 %, preferably less than 1 % and even more preferentially less than 0. 1 % . Non-silicone fatty substances generally have in their structure a hydrocarbon-based chain comprising at least 6 carbon atoms. In addition, the fatty substances are generally so luble in organic so lvents under the same temperature and pressure conditions, such as, for example, chloroform, ethanol, benzene, liquid petroleum j elly or decamethylcyclopentasiloxane .

The non-silicone fatty substances o f the invention are moreover non-polyoxyethylenated and non-polyglycerolated.

The term "non-silicone fatty substance" means a fatty substance not comprising in its structure any Si-O-Si sequences .

The fatty substance(s) may be liquid or non-liquid at room temperature and at atmospheric pressure. The liquid fatty substances of the invention preferably have a viscosity o f less than or equal to 2 Pa. s, better still less than or equal to 1 Pa. s and even better still less than or equal to 0. 1 Pa.s at a temperature of 25 ° C and at a shear rate of 1 s-¹ .

Advantageously, the non-silicone fatty substance(s) are chosen from C₆ to C _{1 6} hydrocarbons, hydrocarbons containing more than 1 6 carbon atoms, oils o f plant or animal origin, triglycerides o f plant or synthetic origin, fluoro oils, fatty alcoho ls, esters of fatty acids and/or of fatty alcoho ls other than triglycerides, non-silicone waxes other than so lid fatty alcoho ls and so lid synthetic esters, ceramides, and mixtures thereof.

Fatty acid and fatty alcoho l denote an acid and an alcoho l, respectively, containing from 6 to 30 carbon atoms, and preferably from 8 to 22 carbon atoms .

Plant oils that may especially be mentioned include sweet almond oil, avocado oil, castor oil, o live oil, liquid jojoba wax, sunflower oil, wheatgerm oil, sesame oil, groundnut oil, grapeseed oil, soybean oil, rapeseed oil, safflower oil, coconut oil, corn oil, hazelnut oil, palm oil, apricot kernel oil, beauty-leaf oil, evening primrose oil, shea butter, rice bran oil, corn germ oil, passion flower oil and rye oil.

An animal oil that may especially be mentioned is perhydrosqualene.

Liquid paraffin or liquid petroleum jelly may especially be mentioned as mineral oil.

Synthetic oils that may especially be mentioned include squalane, poly(a-o lefins), for instance isododecane or isohexadecane, transesterified plant oils, fluoro oils and fatty esters .

The term " fatty esters" denotes compounds o f formula RaCO ORb in which R_a represents a linear or branched, hydroxylated or non-hydroxylated, saturated or unsaturated higher acid residue, comprising from 4 to 29 carbon atoms, and Rb represents a linear or branched, saturated or unsaturated hydrocarbon-based chain containing from 3 to 30 carbon atoms, the total number o f carbon atoms in the ester being greater than 10. Non-limiting examples that may especially be mentioned include Purcellin oil (stearyl octanoate), isopropyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, isononyl isononanoate, 2-ethylhexyl palmitate, 2-hexyldecyl laurate, 2- octyldecyl palmitate, 2-octyldodecyl myristate, isostearyl neopentanoate and tridecyl neopentanoate.

The fluoro oils may be partially hydrocarbon-based and/or silicone-based fluoro oils, for instance those described in document JP-A-2-295 912. The fatty alcohols may be chosen from fatty alcohols that are solid at room temperature and at atmospheric pressure (25°C, 1 atm) and fatty alcohols that are liquid at room temperature and at atmospheric pressure (25°C, 1 atm) and mixtures thereof.

The term "fatty alcohol" means a long-chain aliphatic alcohol comprising from 8 to 40 carbon atoms and comprising at least one hydroxyl group OH. These fatty alcohols are neither oxyalkylenated nor glycerolated.

Preferably, the solid fatty alcohols have the structure R-OH with R denoting a linear alkyl group, optionally substituted with one or more hydroxyl groups, comprising from 8 to 40, better still from 10 to 30, or even from 12 to 24 and even better still from 14 to 22 carbon atoms.

The solid fatty alcohols that may be used may be chosen, alone or as a mixture, from:

- lauryl alcohol (1-dodecanol);

- myristyl alcohol (1-tetradecanol);

- cetyl alcohol (1-hexadecanol);

- stearyl alcohol (1-octadecanol);

- arachidyl alcohol (1-eicosanol);

- behenyl alcohol (1-docosanol);

- lignoceryl alcohol (1-tetracosanol);

- ceryl alcohol (1-hexacosanol);

- montanyl alcohol (1-octacosanol);

- myricyl alcohol (1-triacontanol).

Preferentially, the solid fatty alcohol is chosen from cetyl alcohol, stearyl alcohol, behenyl alcohol and mixtures thereof such as cetylstearyl alcohol or cetearyl alcohol.

The liquid fatty alcohols, in particular the Cio to C34 alcohols, preferably have branched carbon-based chains or have one or more, preferably 1 to 3, unsaturations. They are more preferentially branched and/or unsaturated, and comprise from 12 to 40 carbon atoms, and are non-oxyalkylenated and non-glycerolated.

They preferably have the structure R-OH, in which R preferably denotes a branched C₁₂ to C24 alkyl or C₁₂ to C24 alkenyl group, R possibly being substituted with one or more hydroxyl groups. Preferably, the liquid fatty alcoho l o f the invention is a branched saturated alcoho l. More preferentially, R does not contain any hydroxyl groups.

Mention may especially be made o f o leyl alcoho l, lino leyl alcoho l, lino lenyl alcohol, isocetyl alcohol, isostearyl alcoho l, 2-octyl- 1 -dodecanol, 2-butyloctanol, 2-hexyl- 1 -decanol, 2-decyl- l - tetradecanol and 2-tetradecyl- 1 -cetanol, and mixtures thereof.

Preferentially, the liquid fatty alcohol is 2-octyl- 1 -dodecanol.

For the purposes o f the present invention, a wax is a lipophilic compound, which is so lid at room temperature (about 25 °C), with a reversible so lid/liquid change o f state, having a melting point greater than about 40°C , which may be up to 200°C , and having in the so lid state an anisotropic crystal organization. Animal and plant waxes comprise, as essential constituents, long-chain esters o f carboxylic acids and o f alcoho ls. In general, the size o f the wax crystals is such that the crystals diffract and/or scatter light, giving the composition that comprises them a more or less opaque cloudy appearance. By bringing the wax to its melting point, it is possible to make it miscible with oils and to form a microscopically homogeneous mixture.

As waxes o f use in the composition according to the present invention, mention may be made of waxes o f animal origin such as beeswax, spermaceti, lano lin wax and lanolin derivatives; plant waxes such as sunflower wax, rice wax, apple wax, carnauba wax, candelilla wax, ouricury wax, Japan wax, cocoa butter, cork fibre wax or sugar cane wax; mineral waxes, for example paraffin wax, petroleum jelly wax, lignite wax, microcrystalline waxes, ceresin or ozokerite; synthetic waxes such as polyethylene waxes and Fischer-Tropsch waxes, and mixtures thereof.

Additional non-amino silicones

The composition applied in the first step of the process for treating keratin fibres according to the present invention may optionally also comprise one or more additional non-amino silicone(s) .

The term "non-amino silicone" means any silicone which does not comprise any primary, secondary, tertiary or quaternary amine group, namely any silicone other than the amino silicones mentioned above. The additional non-amino silicones of use in the composition according to the invention are in particular polyorganosiloxanes, which may be in the form of aqueous solutions, i.e. dissolved, or optionally in the form of dispersions or microdispersions, or of aqueous emulsions. The polyorganosiloxanes may also be in the form of oils, waxes, resins or gums.

Organopolysiloxanes are defined in greater detail in Walter Noll's "Chemistry and Technology of Silicones", (1968), Academic Press.

The additional non-amino silicones may be volatile or nonvolatile.

When they are volatile, the non-amino silicones are more particularly chosen from those having a boiling point between 60°C and 260°C, and more particularly still from:

(i) cyclic silicones comprising from 3 to 7 and preferably 4 to 5 silicon atoms.

These are, for example, octamethylcyclotetrasiloxane sold especially under the name Volatile Silicone 7207 by Union Carbide or Silbione 70045 V 2 by Rhodia, decamethylcyclopentasiloxane sold under the name Volatile Silicone 7158 by Union Carbide, and Silbione 70045 V 5 by Rhodia, and mixtures thereof.

Mention may also be made of cyclocopolymers of the dimethylsiloxane/methylalkylsiloxane type, such as Volatile Silicone FZ 3109 sold by Union Carbide of chemical structure:

with D" — Si- O- with D' -Si-O- I I

17

Mention may also be made of mixtures of cyclic silicones with organosilicon compounds, such as the mixture of octamethylcyclotetrasiloxane and tetratrimethylsilylpentaerythritol (50/50) and the mixture of octamethylcyclotetrasiloxane and oxy-1,1'- bis(2,2,2',2',3,3 '-hexatrimethylsilyloxy)neopentane; (ii) linear volatile silicones having 2 to 9 silicon atoms and having a viscosity of less than or equal to 5 * 10^"6 m²/s at 25°C. An example is decamethyltetrasiloxane sold especially under the name SH 200 by Toray Silicone. Silicones belonging to this category are also described in the article published in Cosmetics and Toiletries, Vol. 91, Jan. 76, pp. 27-32, Todd & Byers "Volatile Silicone Fluids for Cosmetics".

When the non-amino silicones are non- volatile, use is preferably made of polyalkylsiloxanes, polyarylsiloxanes, polyalkylarylsiloxanes, silicone gums and resins, and polyorganosiloxanes modified with organofunctional groups, and mixtures thereof.

These non-amino silicones are more particularly chosen from polyalkylsiloxanes, among which mention may be made mainly of polydimethylsiloxanes containing trimethylsilyl end groups (Dimethicone according to the CTFA name) having a viscosity of from 5*10^"6 to 2.5 m²/s at 25°C and preferably 1*10^"5 to 1 m²/s. The viscosity of the silicones is measured, for example, at 25°C according to standard ASTM 445 Appendix C.

Among these polyalkylsiloxanes, mention may be made, in a non-limiting manner, of the following commercial products:

- the Silbione oils of the 47 and 70 047 series or the Mirasil oils sold by Rhodia, for instance the oil 70047 V 500000,

- the oils of the Mirasil series sold by Rhodia,

- the oils of the 200 series from Dow Corning, such as, more particularly, DC200 with a viscosity of 60 000 cSt,

- the Viscasil oils from General Electric and certain oils of the SF series (SF 96, SF 18) from General Electric.

Mention may also be made of polydimethylsiloxanes containing alpha-omega silanol groups (Dimethiconol according to the CTFA name) such as the oils of the 48 series from Rhodia.

In this category of polyalkylsiloxanes, mention may also be made of the products sold under the names Abil Wax 9800 and 9801 by Goldschmidt, which are poly(Ci-C2o)alkylsiloxanes.

The polyalkylarylsiloxanes are particularly chosen from linear and/or branched polydimethylmethylphenylsiloxanes and polydimethyldiphenylsiloxanes with a viscosity o f from 1 * 10^~5 to 5 * 10^"2 m²/s at 25 °C .

Among these polyalkylarylsiloxanes, examples that may be mentioned include the products sold under the following names :

- Silbione oils o f the 70 64 1 series from Rhodia,

- the oils o f the Rhodorsil 70 633 and 763 series from Rhodia,

- the oil Dow Corning 556 Cosmetic Grade Fluid from Dow Corning,

- the silicones of the PK series from Bayer, such as the product PK20,

- the silicones o f the PN and PH series from Bayer, such as the products PN 1000 and PH 1000,

- certain oils o f the SF series from General Electric, such as SF 1 023 , SF 1 154, SF 1250 and SF 1265.

The silicone gums that may be present in the composition according to the invention are especially polydiorganosiloxanes having high number-average mo lecular weights o f between 200 000 and 1 000 000, used alone or as a mixture in a so lvent. This so lvent may be chosen from vo latile silicones, polydimethylsiloxane (PDMS) oils, polyphenylmethylsiloxane (PPMS) oils, isoparaffins, polyisobutylenes, methylene chloride, pentane, dodecane and tridecane, or mixtures thereof.

Mention may be made more particularly o f the fo llowing products :

- polydimethylsiloxane gums,

- polydimethylsiloxane/methylvinylsiloxane gums,

- polydimethylsiloxane/diphenylsiloxane gums,

- polydimethylsiloxane/phenylmethylsiloxane gums,

- polydimethylsiloxane/diphenylsiloxane/methylvinylsiloxane gums.

Products that may be used more particularly are the fo llowing mixtures :

- mixtures formed from a polydimethylsiloxane hydroxylated at the end o f the chain (known as dimethicono l according to the nomenclature o f the CTFA dictionary) and from a cyclic polydimethylsiloxane (known as cyclomethicone according to the nomenclature o f the CTFA dictionary), such as the product Q2 140 1 so ld by Dow Corning, - mixtures formed from a polydimethylsiloxane gum with a cyclic silicone, such as the product SF 1214 Silicone Fluid from General Electric, this product being an SF 30 gum corresponding to a dimethicone, having a number-average molecular weight of 500 000, dissolved in the oil SF 1202 Silicone Fluid corresponding to decamethy Icy clop entasiloxane,

- mixtures of two PDMSs with different viscosities, and more particularly of a PDMS gum and a PDMS oil, such as the product SF 1236 from General Electric. The product SF 1236 is the mixture of a gum SE 30 defined above, with a viscosity of 20 m²/s and of an oil SF 96 with a viscosity of 5*10^~6m²/s. This product preferably includes 15% of gum SE 30 and 85% of an oil SF 96.

The organopolysiloxane resins that may be present in the composition according to the invention are crosslinked siloxane systems containing the following units: R2S1O2/2, R3S1O1/2, RS1O3/2 and S1O4/2 in which R represents a hydrocarbon-based group containing 1 to 16 carbon atoms or a phenyl group. Among these products, those that are particularly preferred are those in which R denotes a Ci to C₄ alkyl group, more particularly methyl, or a phenyl group.

Among these resins, mention may be made of the product sold under the name Dow Corning 593 or those sold under the names Silicone Fluid SS 4230 and SS 4267 by General Electric, which are silicones of dimethyl/trimethylsiloxane structure.

Mention may also be made of the trimethyl siloxysilicate-type resins sold especially under the names X22-4914, X21-5034 and X21- 5037 by Shin-Etsu.

The organomodified non-amino silicones optionally present in the composition according to the invention are non-amino silicones as defined above and comprising in their structure one or more organofunctional groups attached via a hydrocarbon-based group.

Among the organomodified non-amino silicones, mention may be made of polyorganosiloxanes comprising:

polyethyleneoxy and/or polypropyleneoxy groups optionally comprising C₆ to C24 alkyl groups, such as the products known as dimethicone copolyol sold by Dow Corning under the name DC 1248 or the oils Silwet L 722, L 7500, L 77 and L 71 1 by Union Carbide, and the ( C i 2)alkylmethicone copolyo l so ld by Dow Corning under the name Q2 5200,

- thio l groups, such as the products so ld under the names GP 72 A and GP 7 1 from Genesee,

- alkoxylated groups, such as the product sold under the name Silicone Copolymer F-755 by SWS Silicones and Abil Wax 2428 , 2434 and 2440 by Goldschmidt,

- hydroxylated groups, such as the polyorganosiloxanes containing a hydroxyalkyl function, described in French patent application

FR 2 589 476,

- acyloxyalkyl groups, for instance the polyorganosiloxanes described in patent US-A-4 957 732,

- anionic groups of the carboxylic type, for instance in the products described in patent EP 1 86 507 from Chisso Corporation, or of the alkylcarboxylic type, such as those present in the product X-22-3701 E from Shin-Etsu; 2-hydroxyalkyl sulfonate; 2-hydroxyalkyl thio sulfate such as the products so ld by Go ldschmidt under the names Abil S201 and Abil S255 ,

- hydroxyacylamino groups, for instance the polyorganosiloxanes described in patent application EP 342 834. Mention may be made, for example, of the product Q2-84 13 from Dow Corning.

The composition applied in the first step of the process for treating keratin fibres according to the present invention may also optionally comprise one or more additives, different from the compounds o f the invention, and among which mention may be made of cationic, anionic, nonionic, amphoteric or zwitterionic surfactants, cationic, anionic, nonionic or amphoteric polymers or mixtures thereo f, antidandruff agents, anti-seborrhoea agents, agents for preventing hair lo ss and/or for promoting hair regrowth, vitamins and provitamins including panthenol, sunscreens, mineral or organic pigments, sequestrants, plasticizers, so lubilizers, acidifying agents, mineral or organic thickeners, especially polymeric thickeners, opacifiers or nacreous agents, antioxidants, hydroxy acids, fragrances, preserving agents, pigments and ceramides . Of course, those skilled in the art will take care to select this or these optional additional compound(s) such that the advantageous properties intrinsically associated with the compositions according to the invention are not, or are not substantially, adversely affected by the envisaged addition(s) .

The above additives may generally be present in an amount, for each o f them, o f between 0 and 20% by weight relative to the total weight of the composition.

The composition applied in the first step of the process according to the invention may be in the form o f a wax, a paste, a cream, a gel, a foam, a spray or a lotion.

B) Heat treatment

The process for treating keratin fibres according to the present invention also comprises a second step of heat treatment of the keratin fibres at a temperature greater than or equal to 100°C .

The second step fo llows the first step . In other words, the composition as defined above is applied before the heat treatment o f the keratin fibres.

This step o f heat treatment of the keratin fibres is preferably performed at a temperature ranging from 100°C to 250°C , and better still from 1 80°C to 230°C .

Preferably, the heat treatment step is performed for a duration ranging from 2 seconds to 1 hour, preferably ranging from 5 seconds to 1 minute, per lock of hair.

This step of heat treatment is generally carried out by means o f a heating tool which may in particular be chosen from irons and steam irons.

For the purposes o f the present invention, the term " iron" means a device for heating keratin fibres by placing said fibres in contact with the heating device. The end of the iron which comes into contact with the keratin fibres generally has two flat surfaces. These two surfaces may be made o f metal or o f ceramic. In particular, these two surfaces may be smooth or crimped or curved.

For the purposes o f the present invention, the term "steam irons" means irons which comprise a device which emits steam and which applies this steam before, during or after the straightening/relaxing.

As examples o f irons that may be used in the straightening process according to the invention, mention may be made o f any type of flat iron with steam, and in particular, in a non-limiting manner, those described in patents US 5 957 140 and US 5 046 5 16.

The steam iron may be app lied by successive separate strokes lasting a few seconds or by gradual movement or sliding along the lo cks o f keratin fibres, especially of hair.

Preferably, the steam iron is applied in the process according to the invention by a continuous movement from the root to the end o f the hair, in one or more passes, in particular in two to twenty passes . The duration o f each pass o f the steam iron may range from 2 seconds to 1 minute.

Advantageously, steam is applied to the keratin fibres, especially the hair, at a flow rate of less than 5 g/min, in particular o f between 1 and 4 g/min.

Steam may be applied using any device known per se for generating the amount of steam o f use in the process o f the invention. According to a particular embodiment, this machine is portable, i. e . the tank for generating steam is in contact with the part o f the device comprising the steam-dispensing orifices .

The steam application step may be performed before, during or after the heating step , and preferably before .

Preferably, said second step of the process according to the invention is performed with a steampod steam straightening device.

Preferably, the second step o f heat treatment also comprises a mechanical treatment, performed for example by means o f a straightening iron.

Advantageously, the second step o f heat treatment o f the keratin fibres is carried out directly after application o f the composition, without an intermediate rinsing step .

Preferably, the second step o f heat treatment is carried out after a leave-on time of the composition applied in the first step which ranges from 5 minutes to 1 hour. In a first embodiment of the process according to the invention, the composition is applied to a wet or dry head of hair, preferably dry, with or without a leave-on time.

According to this first embo diment, the bath ratio of the formulation applied may range from 0. 1 to 10, more particularly from 0.2 to 5. For the purposes o f the present invention, the term "bath ratio" means the ratio between the total weight of the applied composition and the total weight of keratin fibres to be treated.

The keratin fibres are then optionally rubbed dry, preferably rubbed dry. One or more heating means are applied once or in succession to the keratin fibres at a temperature advantageously greater than or equal to 100°C , preferably ranging from 100° C to 250°C, and more preferentially from 1 80° C to 230°C, for a time ranging from 5 seconds to one hour and preferably from 5 seconds to one minute, per lock of hair.

The hair then optionally undergoes one or more of the fo llowing operations : rinsing, shampooing and treatment with a rinse- out conditioner, drying, preferably using a hood or a hairdryer.

In general and preferably in the process according to the invention, the step o f application o f the composition to the keratin fibres is performed on dry keratin fibres .

In a second embodiment, the process according to the invention is performed one or more times, optionally spaced apart by one or more cosmetic treatments, preferably spaced apart by one or more shampooing operations, to treat hair that has regrown or that has undergone other treatments liable to cause changes in the curliness, or to obtain the desired shape or the desired shape intensity.

Preferably, the process according to the invention does not comprise the application of a reducing composition either before or during or after the application of the composition of use in the process according to the invention.

This is particularly advantageous in the context of the present invention since it makes it possible to perform a process that is sparingly aggressive to the hair.

Another subj ect of the present invention is a suitable composition for carrying out the process o f the invention, this composition being as defined above; said composition being aqueous and having an acid pH.

The term "aqueous composition" means a composition comprising at least 5 % by weight of water, relative to the weight o f this composition.

Preferably, the aqueous composition according to the invention comprises more than 10% by weight of water and even more advantageously more than 20% by weight of water, relative to the total weight thereof.

The present invention also relates to the use o f a composition as defined above for straightening and/or relaxing keratin fibres, in particular human keratin fibres such as the hair.

This composition may mo st particularly be used for straightening and/or relaxing hair which has undergone a bleaching treatment.

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

EXAMPLES

I . Example 1 : in vivo tests on models a) Preparation o f the compositions

The composition according to the invention (A l ) and the comparative composition (B l ) were prepared from the ingredients, the amounts of which are indicated, as percentage by weight relative to the total weight of each of the compositions, in the table below.

Al B l

(invention) (comparative)

Maleic acid 10 10

Amo dimethicone ^ 10 -

Distilled water qs 100 qs 100

pH 1 1 ^{( >} Polydimethylsiloxane containing aminoethyliminopropyl groups in cationic emulsion at 60% by weight in water (Dow Corning 2-8299 Cationic Emulsion from Dow Corning) b) Protocol

The compositions (Al ) and (B l ) obtained in this way were applied to models at an amount of 20 grams o f composition per half head of natural grey hair of Caucasian type.

The locks were then subj ected to 5 successive blow drying passes, at position 2 (80° C) of the hairdryer, with a medium-diameter round brush. Each o f the locks was then separated in 2, and each part underwent 10 passes o f the straightening iron using a comb, at a temperature of 190°C for the bleached locks or of 210°C for the natural lo cks. The lo cks then underwent 3 passes using this same straightening iron.

The locks were then rinsed with water, then washed with a conventional commercially available shampoo (Ultra-Doux^® type) .

Each lock was then pressed at various points so as not to interfere with the curl, then dried flat.

This straightening protocol was also carried out on control lo cks, to which neither o f the compositions (A l ) or (B l ) had been applied.

The cosmetic properties and also the immediate straightening and the respect for the co lour of the locks o f hair were then evaluated by an expert in sensorial terms (visual and touch) and a grade was assigned according to the fo llowing criteria : no effect (-), slight effect (+), pronounced effect (++), significant effect (+++) or very significant effect (++++) . c) Results

The results o f the cosmetic properties obtained for the natural hair are given in the fo llowing table (mean value for 10 different half heads) . Respect

Immediate Cosmetic

for the

straightening appearance

co lour

Al

++++ ++++ ++++

(invention)

B l

+++ +++ +++

(comparative)

The results obtained above show that the process according to the invention using the composition (Al ) makes it possible to obtain immediate straightening and provides better cosmetic properties than the comparative process using the composition (B l ) .

In addition, the process according to the invention better respects the colour of the treated hair than the comparative process .

II .Example 2 : in vitro tests on locks of hair a) Preparation o f the compositions

The composition according to the invention (A l ) and the comparative composition (B2) were prepared from the ingredients, the amounts of which are indicated, as percentage by weight relative to the total weight of each of the compositions, in the table below.

^{( >} Polydimethylsiloxane containing aminoethyliminopropyl groups in cationic emulsion at 60% by weight in water (Dow Corning 2-8299 Cationic Emulsion from Dow Corning) b) Protocol

The compositions (Al ) and (B2) obtained in this way were applied to wet BRAZ (Brazilian) type IV locks (natural and/or bleached lo cks) according to a bath ratio of 2 g/ 1 g o f lo ck, in order for the locks to be thoroughly impregnated.

The locks were then subj ected to 5 successive blow drying passes, at position 2 (80° C) of the hairdryer, with a medium-diameter round brush. Each o f the locks was then separated in 2, and each part underwent 10 passes o f the straightening iron using a comb, at a temperature of 190° C for the bleached locks or of 210°C for the natural lo cks. The lo cks then underwent 3 passes using this same straightening iron.

This straightening protocol was also carried out on control lo cks, to which neither o f the compositions (A l ) or (B2) had been applied.

The immediate straightening and also the properties o f touch and manageability o f the lo cks o f hair were then evaluated by an expert in sensorial terms (touch and visual) and a grade was assigned according to the fo llowing criteria : no effect (-), slight effect (+), pronounced effect (++), significant effect (+++) or very significant effect (++++) .

The durability (or persistence) o f these properties was then evaluated after a cycle o f 10 shampooing operations carried out for each o f the locks tested. An overall grade was assigned for durability, according to the same criteria as above. c) Results

The results obtained for the bleached and natural lo cks are given in the fo llowing tables 1 and 2 (mean value for 4 different lo cks) . Table 1: bleached locks

Table 2: natural locks

The above results show that the process according to the invention using the composition (Al) provides better straightening of the hair than the comparative process using the composition (B2). The straightening with the process according to the invention is immediate and lasts longer than that obtained with the comparative process. The hair is also more well-behaved.

III. Example 3: evaluation of friction and suppleness of the locks a) Compositions

The compositions used are the compositions (Al), (Bl) and (B2) described in examples 1 and 2 above. b) Protocol

The compositions (A l ), (B l ) and (B2) obtained in this way were applied to wet bleached Caucasian type II locks of hair according to a bath ratio of 2 g/ 1 g o f lock, in order for the locks to be thoroughly impregnated.

This straightening protocol was also carried out on control lo cks, to which none of the compositions (A l ), (B l ) and (B2) had been applied. c) Friction evaluation

The lo cks of hair obtained above were fixed to the samp le ho lder of a Zwickiline Z2.5 materials testing machine (ZWICK, Germany) . A normal force of 0.5 N was applied to each of the locks by grasping them in a clamp covered with strips o f disposable fo am. The foam was removed and replaced after each measurement. A constant displacement speed of 100 mm/min was set by the machine.

The force was recorded over time and represented in the form of a force-displacement curve reaching a plateau after a few seconds, then the mean friction force at the plateau was recorded.

The impact o f the application o f the compositions (A l ) and (B l ) to the friction o f the hair was obtained by comparing the mean friction force o f the untreated locks o f hair (control locks) with the friction force of the locks treated by said compositions . For the wet measurements (wet friction force), the locks of hair were submerged beforehand in distilled water for one minute before carrying out the friction measurement as described above. The dry and wet friction values obtained for the process according to the invention using the composition (Al ) and the comparative process using the composition (B l ) are given in figure 1 .

These results show that the process according to the invention, i.e . using a composition comprising both maleic acid and amodimethicone, leads to a significant reduction in the friction o f the lo ck, both wet and dry, compared to the comparative process in which only maleic acid is used. d) Evaluation o f suppleness

The locks o f hair obtained above were subj ected to flexural stress at a constant rate. The force (in newtons) applied to each o f the lo cks as a function o f their disp lacement was then measured, thereby making it possible to determine the maximum flexural force for each of the locks .

The higher the value o f the force applied, the stiffer the lo cks; that is to say the less supple the locks . Conversely, the lower the value of the force applied, the more supple the locks.

The suppleness values obtained for the process according to the invention using the composition (A l ) and the comparative processes using the compositions (B l ) and (B2) are given in figure 2.

These results show that the process according to the invention, using the combination o f maleic acid and amodimethicone (Al ), provides significantly more suppleness to the hair (both wet and dry) than the comparative processes in which maleic acid (B l ) or amodimethicone (B2) are used alone . Indeed, the value o f the maximum flexural force obtained for the locks treated with the composition according to the invention (A l ) is lower than that obtained for the locks treated with the comparative compositions (B l ) and (B2). e) Evaluation o f the hydrophilic-hydrophobic balance

The lo cks of hair obtained above were submerged in water. The energy o f penetration o f the locks in the water was then measured, thereby making it possible to determine the degree o f hydrophobicity of the locks .

Figure 3 presents the results obtained for the process according to the invention using the composition (A l ), and the comparative process using the composition (B l ), in terms o f energy o f penetration of the locks in the water. Figure 3 also presents the ranges within which the locks are considered to be hydrophilic or hydrophobic.

These results show that the combination o f maleic acid and amodimethicone makes it possible to restore a hydrophobic surface to the hair, and especially to bleached hair.

IV. Example 4 : in vitro evaluation on locks of hair a) Preparation o f the compositions

The composition according to the invention (A2) and the comparative composition (B3) were prepared from the ingredients, the amounts of which are indicated, as percentage by weight relative to the total weight of each of the compositions, in the table below.

(ⁱ > Polydimethylsiloxane containing aminoethyliminopropyl groups in cationic emulsion at 60% by weight in water (Dow Corning 2-8299 Cationic Emulsion from Dow Corning) b) Protocol

The compositions A2 and B3 obtained in this way were applied to wet BRAZ type IV locks (natural locks) according to a bath ratio of 2 g/ 1 g of lock, in order for the locks to be thoroughly impregnated. The locks were then subj ected to 5 successive blow drying passes, at position 2 (80° C) of the hairdryer, with a medium-diameter round brush. Each of the locks was then separated in 2, and each part underwent 10 passes o f the straightening iron using a comb, at a temperature o f 210°C for the natural locks. The locks then underwent 3 passes using this same straightening iron.

This straightening protocol was also carried out on control lo cks, to which neither of the compositions A2 or B3 had been applied.

The durability (or persistence) of these properties was then evaluated after a cycle o f 10 shampooing operations carried out for each o f the locks tested. An overall grade was assigned for durability, according to the same criteria as above. c) Results

The results obtained for the natural lo cks are given in the fo llowing table (mean value for 4 different locks) . Immediate

Feel Manageability Durability straightening

A2

+++ +++ +++ +++

(invention)

B3

++ ++ ++ ++

(comparative)

Control

- - - - (water)

The above results show that the process according to the invention using the composition (A2) provides better straightening o f the hair than the comparative process using the composition (B3) . The straightening with the process according to the invention is immediate and lasts longer than that obtained with the comparative process. The hair is also more well-behaved and has a better feel. V. Example 5 a) Preparation o f the compositions

The composition according to the invention (A3) and the comparative composition (B4) were prepared from the ingredients, the amounts o f which are indicated, as percentage by weight relative to the total weight of each of the compositions, in the table below.

^{( >} Polydimethylsiloxane containing aminoethylaminopropyl groups containing methoxy and/or hydroxyl and α- ω silano l functions in cationic emulsion at 60% by weight in water b) Protocol

2.7g BRAZ (Brazilian) type IV natural locks were placed flat on a sheet of aluminium foil on a plate at 37°C . 5.4g o f each compositions (A3) and (B4) obtained here above were app lied to the lo cks with a staining brush in order to have a homogeneous treatment.

After a leave-on time of 30 minutes, the locks were wrung with a paper and rinsed with water ( 10 passes between the fingers) .

The lo cks were then subj ected to 10 successive blow drying passes, at position 2 (80° C) of the hairdryer, with a medium-diameter round brush, and they underwent 10 passes of the straightening iron in 6 seconds, at a temperature of 230°C .

The locks were then washed with a shampoo .

For each lo ck, the length and the diameter at mid-length have been measured with a graduated ruler of 30cm. c) Results

The results thus obtained are given in the table below.

The above results show that the process according to the invention using the composition (A3), which comprises maleic acid, provides a better straightening o f the hair than the comparative process using the comparative composition (B4), which comprises lactic acid. The lock o f hair treated with the process of the present invention is indeed longer and thinner than the lock of hair treated with the comparative process .

Claims

1 . Process for treating keratin fibres, in particular human keratin fibres such as the hair, preferably bleached, comprising the fo llowing steps :

in which formula (I) Ri and R₂, which are identical or different, independently from one another represent a hydrogen atom, a linear or branched C i to C i o alkyl group, or a linear or branched C₂ to C i o alkenyl group, said alkyl or alkenyl groups being :

optionally substituted by one or more radicals chosen from hydroxyl, amino, C i to C₆ mono- or dialkylamino , C i to C₆ alkoxy, and carboxyl radicals; and

- one or more amino silicones;

fo llowed by

2) a second step of heat treatment of said keratin fibres at a temperature greater than or equal to 100°C .

2. Process according to Claim 1 , characterized in that Ri and Pv2 , which are identical or different, independently from one another represent a hydrogen atom or a linear or branched C i to C₆ alkyl group, optionally substituted by one or more carboxyl radicals.

3. Process according to either one o f the preceding claims, characterized in that the compound(s) o f formula (I) are chosen from maleic acid, citraconic acid, aconitic acid, the geometric isomers thereo f, the addition salts thereof, and the mixtures thereof.

4. Process according to any one of the preceding claims, characterized in that the total amount o f the compound(s) o f formula (I) ranges from 1 to 20% by weight and preferably from 5 to 15 % by weight relative to the total weight of the composition.

5. Process according to any one of the preceding claims, characterized in that the amino silicone(s) are chosen from the families o f compounds (a) to (e) below: (a) the compounds corresponding to the following formula (II) :

(R¹ ) a(T) ₃ -a-Si[OSi(T)₂]„- [O Si(T)b(R¹ ) 2-b] _m-OSi(T) ₃ -a-(R¹ ) a (II) in which formula (II)

- T is a hydrogen atom or a phenyl, hydroxyl (-OH), or C i -Cs alkyl, and preferably methyl, or C i -Cs alkoxy, preferably methoxy, group,

- a denotes the number 0 or an integer from 1 to 3 , and preferably 0,

- b denotes 0 or 1 , and in particular 1 ,

- R¹ is a monovalent group of formula

i) -CqH_{2 q}L, wherein q is an integer between 2 and 8 inclusive and L is an optionally quaternized amino group chosen from the groups : -N(R²)-ALK-N(R²)₂,

-N(R²)₂,

-N⁺(R²)₃ Q-,

-N(R²)-ALK-N⁺(R²)₂ Q ,

in which:

* R², which are identical or different, denote a hydrogen atom, a phenyl group, a benzyl group or a C i -C₂o alkyl group,

* Q^" represents an anionic counterion enabling the electrical neutrality of the polymer, preferably a halide ion such as, for example, fluoride, chloride, bromide or iodide, and

* ALK represents a linear or branched (C i -C₆) alkylene group, such as ethylene -CH₂-CH₂-; or else

ii) -CqH_{2 q}-i L', wherein q is an integer between 2 and 8 inclusive and L ' is an optionally quaternized imino group chosen from the groups :

=N-ALK-N(R²)₂,

=N-R²,

=N⁺(R²)₂ Q ,

=N-ALK-N⁺(R²)₃ Q

with ALK, R² and Q^" as defined for L;

in particular, the amino silicones corresponding to the definition o f formula (II) are chosen from the compounds corresponding to the fo llowing formula (III) or (III ' ) :

(III)

in which formulae (III) or (ΙΙΓ):

• R, R' and R", which are identical or different, denote a C1-C4 alkyl group, preferably CH3, a C1-C4 alkoxy group, preferably methoxy, or OH,

• A represents a linear or branched C3-C8 and preferably C3-C6 alkylene group,

• A' represents an alkylene group -(CR^aR^b)_p-C(R^c)= with p representing an integer between 0 and 5 inclusive, and R^a, R^b, and R^c, which are identical or different, representing a hydrogen atom or a (C1-C4) alkyl group, preferably R^a, R^b, and R^c represent a hydrogen atom,

• m and n, which are identical or different, are integers that are dependent on the molecular weight and whose sum is between 1 and 2000;

(b) the compounds corresponding to the following formula (V)

(V) in which formula (V)

- R³ represents a monovalent Ci-Cis hydrocarbon-based group, and in particular a Ci-Cis alkyl or C2-C18 alkenyl group, for example methyl,

- R⁴ represents a divalent hydrocarbon-based group, especially a Ci- Ci8 alkylene group or a divalent Ci-Cis, for example Ci-Cs, alkyleneoxy group,

- Q^" is an anionic counterion, in particular halide, especially chloride,

- r represents a mean statistical value from 2 to 20 and in particular from 2 to 8,

- s represents a mean statistical value from 20 to 200 and in particular from 20 to 50;

(c) the quaternary ammonium silicones of formula (VI)

in which formula (VI)

- R7, which are identical or different, represent a monovalent hydrocarbon-based group having from 1 to 18 carbon atoms, and in particular a Ci-Cis alkyl group, a C2-C18 alkenyl group or a ring comprising 5 or 6 carbon atoms, for example methyl,

- R₆ represents a divalent hydrocarbon-based group, especially a Ci- Ci8 alkylene group or a divalent Ci-Cis, for example Ci-Cs, alkyleneoxy group linked to the Si via an Si-C bond, - R-8, which are identical or different, each represent a hydrogen atom, a monovalent hydrocarbon-based group having from 1 to 18 carbon atoms, and in particular a Ci-Cis alkyl group, a C2-C18 alkenyl group or an -R6-NHCOR7 group,

- X^" is an anionic counterion such as a halide ion, especially chloride or an organic acid salt,

- r represents a mean statistical value from 2 to 200 and in particular from 5 to 100;

(d) the amino silicones of formula (VII) or (VIF):

H₂N-(C_mH_2m)-N-(C_nH_2n)-Si O R_c

(VII)

H₂N-(C_mH_2m)-N = (C_nH_2n.1)-Si O Si O Si R.

FL R,

(VIF)

in which formulae (VII) and (VIF):

- R5 denotes a Ci-C₄ alkyl group or a hydroxyl group,

- n is an integer ranging from 1 to 5,

- m is an integer ranging from 1 to 5, and

- x is chosen such that the amine number is between 0.01 and 1 meq/g; and

(e) mixtures thereof.

6. Process according to any one of the preceding claims, characterized in that the amino silicone(s) are chosen from poly(di)(Ci-C6)alkylsiloxanes containing imino(Ci-C6)alkyl groups or containing (di)(Ci-C6)(alkyl)amino(Ci-C6)alkylimino(Ci-C6)alkyl groups; preferably from polydi(Ci-C4)alkylsiloxanes containing imino(Ci-C4)alkyl groups or containing (di)(C₁-C₄)(alkyl)amino(C₁- C4)alkylimino(Ci-C4)alkyl groups and more preferentially from polydimethylsiloxanes containing imino(Ci-C4)alkyl groups or containing amino(Ci-C3)alkylimino(Ci-C4)alkyl groups such as polydimethylsiloxanes containing iminopropyl or aminoethyliminopropyl groups.

7. Process according to any one of the preceding claims, characterized in that the composition applied in the first step of the process also comprises one or more surfactants chosen from cationic surfactants, nonionic surfactants, and mixtures thereof; and preferably cationic surfactants.

8. Process according to any one of the preceding claims, characterized in that the total amount of the amino silicone(s) ranges from 0.5 to 20% by weight, preferably from 1 to 10% by weight and more preferentially from 2 to 5% by weight, relative to the total weight of the composition.

9. Process according to any one of the preceding claims, characterized in that the weight ratio between the total amount of the compound(s) of formula (I) and the total amount of the amino silicone(s) ranges from 0.1 to 10, preferably from 0.5 to 5, more preferentially from 1 to 4 and better still from 1.5 to 3.

10. Process according to any one of the preceding claims, characterized in that the composition applied in the first step of the process also comprises one or more alkaline agents.

11. Process according to Claim 10, characterized in that the alkaline agents are chosen from mineral, organic or hybrid alkaline agents, and mixtures thereof, and more preferentially from aqueous ammonia, alkali metal carbonates or bicarbonates such as sodium carbonate or bicarbonate, potassium carbonate or bicarbonate, sodium hydroxide or potassium hydroxide, organic amines chosen from alkano lamines, oxyethylenated and/or oxypropylenated ethylenediamines, amino acids and the polyamines o f formula (VIII), and mixtures thereof:

N - W - N

y ^Kt (vill)

in which formula (VIII) W is a divalent C i to C₆ alkylene radical optionally substituted with one or more hydroxyl groups or a C i to C₆ alkyl radical, and/or optionally interrupted with one or more heteroatoms such as O , or NR_U ; R_x, R_y , Rz, Rt, and R_u which are identical or different, represent a hydrogen atom, a C i to C₆ alkyl or C i to C₆ hydroxyalkyl or C i to C₆ amino alkyl radical.

12. Process according to Claim 10 or 1 1 , characterized in that the alkaline agent(s) are chosen from aqueous ammonia, alkanolamines and mixtures thereof, and preferably from aqueous ammonia, mono-, di- or tri- hydroxy(C i -C6)alkylamines, such as triethanolamine, and mixtures thereof.

13. Process according to any one o f Claims 10 to 12, characterized in that the weight ratio between the total amount of the compound(s) o f formula (I) and the total amount o f the alkaline agent(s) ranges from 1 to 5 , preferably from 1 .5 to 3 and more preferentially from 1 .5 to 2.5.

14. Process according to any one o f the preceding claims, characterized in that the pH of the composition ranges from 0.5 to 5 , preferably from 1 to 4 and more preferentially from 1 to 1 .5.

15. Process according to any one o f the preceding claims, characterized in that the step of heat treatment o f the keratin fibres is performed at a temperature ranging from 100° C to 250°C , and more preferentially from 1 80°C to 230°C .

16. Process according to any one o f the preceding claims, characterized in that a step of mechanical treatment for relaxing the keratin fibres, such as brushing, preferably accompanied by heating from a hairdryer, is carried out between the first and second step o f the process .

17. Process according to any one o f Claims 1 to 15 , characterized in that the step of heat treatment o f the keratin fibres is carried out directly after application o f the composition, without an intermediate rinsing step .

1 8. Composition as defined in the first step of the process in any one o f Claims 1 to 14, characterized in that said composition is aqueous and has an acid pH.

19. Use of the composition as defined in Claim 1 8 , for straightening and/or relaxing keratin fibres, in particular human keratin fibres such as the hair.