WO2014029657A2

WO2014029657A2 - Keratin fibre bleaching composition in compressed form comprising two layers

Info

Publication number: WO2014029657A2
Application number: PCT/EP2013/066834
Authority: WO
Inventors: Isabelle Rollat; Gautier Deconinck; Sylvain Kravtchenko; Claire CORIZIA
Original assignee: L'oreal
Priority date: 2012-08-23
Filing date: 2013-08-12
Publication date: 2014-02-27
Also published as: FR2994648A1; WO2014029657A3; FR2994648B1

Abstract

Keratin fibre bleaching composition in compressed form comprising two layers The subject of the present invention is a composition for bleaching keratin fibres which is in compressed form, comprising at least one first layer comprising at least one persulfate and at least one second layer comprising at least one hydrogen peroxide generator.

Description

Keratin fibre bleaching composition in compressed form comprising two layers

The present invention relates to a composition for bleaching keratin fibres, in particular the hair, in compressed form, comprising two separate layers, one comprising a persulfate and the other layer comprising a hydrogen peroxide generator.

The bleaching of human keratin fibres, and more particularly the hair, is performed by oxidation of the "melanin" pigment resulting in the dissolution and the partial or total removal of this pigment.

To bleach the hair, use is in particular made of bleaching powders containing a peroxygenated reagent, such as ammonium persulfates, perborates and percarbonates or alkali metal persulfates, perborates and percarbonates, which is combined, at the time of use, with an aqueous hydrogen peroxide composition. Since peroxygenated salts and hydrogen peroxide are relatively inefficient in acidic medium, it is often necessary to activate them at basic pH in order to obtain an adequate formation of active oxygen. It is thus common practice to add to the bleaching powders alkaline compounds such as alkali metal or alkaline- earth metal silicates and dibasic or tribasic phosphates, and in particular alkali metal metasilicates, optionally in the presence of ammonia precursors such as ammonium salts.

However, bleaching powders have a tendency to form dust during their handling, transportation and storage.

Now, the products of which they are composed (alkali metal persulfates and silicates) are aggressive and in particular irritant to the eyes, the respiratory pathways and mucous membranes.

To overcome the problem of the volatility of bleaching powders, less volatile powders have been developed by adding additives for reducing the content of fine particles, and pastes have been developed comprising said pulverulent agents (peroxygenated salts, alkaline agents, thickeners) in an organic inert liquid support. However, these less volatile powders and these pastes may prove to be less effective than the simple starting powders. Moreover, pastes, just like powders, nevertheless require certain precautions during their handling, in particular as regards weighing them out in order to mix them with the oxidizing composition, so as to avoid staining clothing.

The aim of the present invention is to provide a composition for bleaching keratin fibres that can solve the problems of the handling of the compositions known in the prior art, in particular a composition for bleaching keratin fibres that is in compressed form comprising at least two separate layers, one comprising a persulfate and the other layer comprising a hydrogen peroxide generator, to be mixed directly at the time of use with water.

This composition makes it possible to avoid the handling problems linked to the volatility of the powders or the weighing-out problems by proposing an all-in-one product in a solid compact and ready-to-use form, without a step of metering out, which contains the persalt and the oxidant within a single product and is employed by simple dissolution in water.

This composition also makes it possible to improve the resistance of the composition for bleaching keratin fibres to temperature variations, and in particular makes it possible to avoid the problem of destabilization on storage at low temperatures and during transportation including temperature cycles. It also makes it possible to avoid losses of lightening power.

These objectives are achieved with the present invention, the subject of which is a composition for bleaching keratin fibres, which is in compressed form, comprising at least one first layer comprising at least one persulfate and at least one second layer comprising at least one hydrogen peroxide generator.

The composition according to the invention is in compressed or compacted form, i.e. it has been obtained via a process of compression (or compacting) of particles, in particular by compression or compacting of a powder or of granules. In particular, the composition is obtained by application of a compression force, which the value may range, for example, from 0.1 to 500 MPa and in particular from 0.2 to 100 MPa. Preferably, the bleaching composition in compressed form according to the invention has at least one dimension greater than 6 mm, preferably greater than or equal to 8 mm and preferably greater than or equal to 10 mm.

In particular, it has at least one smaller dimension and at least one larger dimension, the largest of the dimensions being greater than 6 mm, preferably greater than or equal to 8 mm and preferably greater than or equal to 10 mm.

The composition according to the invention may be in compressed form, in particular in the form of a lozenge, a pastille, a pebble, etc., which may have flat or curved, concave or convex upper and lower faces and of round, oval, square, rectangular, octagonal or polygonal shape.

According to one embodiment, the composition in compressed form may be, for example, in the form of a pastille or tablet of round shape, and may have a diameter ranging from 1 to 5 cm and in particular from 2 to 4 cm and a thickness ranging from 1 to 20 mm and in particular from 3 to 10 mm.

According to one embodiment, the composition in compressed form may be, for example, in the form of a lozenge, and may have a length ranging from 1 to 10 cm, a width ranging from 0.5 to 5 cm and a thickness ranging from 0.5 to 20 mm and in particular from 1 to 10 mm.

The composition in compressed form according to the invention may have a mass ranging from 0.5 to 20 grams and preferably from 5 to 15 grams.

The composition according to the invention in compressed form may also be in the form of a pastille or tablet of round shape, and may then have a diameter ranging from 0.5 to 3 cm and in particular from 1 to 2 cm and a thickness ranging from 1 to 20 mm and in particular from 3 to 10 mm. It may thus have a mass ranging from 0.5 to 10 grams.

A subject of the present invention is also a process for bleaching keratin fibres, which consists in applying to the keratin fibres the bleaching composition defined above, in the presence of an aqueous composition.

Unless otherwise indicated, the limits of the ranges of values that are given in the context of the present invention are included in these ranges. In the text hereinabove or hereinbelow, the term "at least one" is equivalent to "one or more".

Persulfates

The first layer of composition in compressed form according to the invention comprises at least one persulfate as peroxygenated salt. Preferably, the persulfate(s) is (are) chosen from sodium persulfates, potassium persulfates and ammonium persulfates, and mixtures thereof.

The persulfate concentration in the composition in accordance with the invention is generally between 10% and 80% by weight, preferably between 20% and 70% by weight and better still between 40% and 65% by weight relative to the total weight of the composition. Alkaline agents

The first layer of bleaching composition in compressed form according to the invention may advantageously comprise at least one alkaline agent.

The alkaline agent(s) may be chosen, for example, from water-soluble silicates such as alkali metal or alkaline-earth metal silicates, such as the dibasic or tribasic ammonium phosphate, sodium disilicate, sodium metasilicate, dibasic or tribasic alkali metal or alkaline-earth metal phosphates or carbonates of alkali metals or alkaline-earth metals, such as lithium, sodium, potassium, magnesium, calcium and barium, and mixtures thereof. Preferably, the alkaline agent(s) are chosen from water-soluble silicates such as alkali metal or alkaline-earth metal silicates, dibasic or tribasic alkali metal or alkaline-earth metal phosphates, and alkali metal or alkaline-earth metal carbonates, and mixtures thereof.

In the context of the invention, the term "water-soluble silicate" is understood to mean a silicate which has a solubility in water of greater than 0.5% and preferably greater than 1 % by weight at 25°C. These water-soluble silicates differ from aluminium silicates and derivatives thereof, in particular clays, such as mixed silicates of natural or synthetic origin that are insoluble in water. When they are present in the composition in accordance with the invention, the concentration of alkaline agents generally ranges from 0.1 % to 40% by weight, preferably from 0.5% to 30% by weight and better still from 1 % to 25% by weight relative to the total weight of the composition.

Hydrogen peroxide-generating agent

As hydrogen peroxide-generating agent that is present in the second layer of the composition in compressed form according to the invention, mention may be made of

polymeric complexes that can release hydrogen peroxide, such as polyvinylpyrrolidone/H₂02 in particular in the form of powders, and the other polymeric complexes described in the documents US 5 008 093; US 3 376 1 10; US 5 183 901 ,

- urea peroxide,

alkali metal, alkaline-earth metal or ammonium perborates and percarbonates, in particular percarbonates such as sodium percarbonate, and mixtures thereof. A hydrogen peroxide generator chosen from urea peroxide and alkali metal or alkaline-earth metal percarbonates, in particular sodium percarbonate, is preferably used.

It may be noted that alkali metal, alkaline-earth metal or ammonium persulfates are not included in these precursors since, in the redox mechanisms using these persulfates, there is no release of hydrogen peroxide.

The hydrogen peroxide-generating agent(s) may represent from 1 % to 40% by weight, preferably from 5% to 30% by weight and better still from 10% to 20% by weight relative to the total weight of the composition.

According to one embodiment, the second layer of the composition in compressed form according to the invention essentially comprises the hydrogen peroxide-generating agent(s), that is to say that it comprises less than 5%, preferably less than 3%, better still less than 1 %, even better still less than 0.5% of additional compound other than the hydrogen peroxide generators.

Rheology modifiers

According to one embodiment, the bleaching composition according to the invention advantageously comprises at least one rheology modifier chosen from hydrophilic thickeners, amphiphilic polymers comprising at least one hydrophobic chain, and fillers, and mixtures thereof.

The rheology modifier may be present in the first and/or the second layer of composition, preferably in the first layer of composition.

The rheology modifier(s) may be present in a content ranging from 0.01 % to 30% by weight, relative to the total weight of the composition, and preferably from 0.1 % to 10% by weight.

As examples of hydrophilic thickeners, i.e. thickeners not comprising a C₆-C₃₀ hydrocarbon-based fatty chain, which may be used according to the invention, mention may be made in particular of:

- thickening polymers of natural origin such as

a) algal extracts, such as alginates (for instance alginic acid and sodium alginates), carrageenans and agar agars, and mixtures thereof. Examples of carrageenans that may be mentioned include Satiagum UTC30^® and UTC10^® from the company Degussa; an alginate that may be mentioned is the sodium alginate sold under the name Kelcosol^® by the company ISP;

b) gums, such as xanthan gum, guar gum and non-ionic derivatives thereof (hydroxypropyl guar), gum arabic, konjac gum or mannan gum, gum tragacanth, ghatti gum, karaya gum or locust bean gum; agar gum, and scleroglucan gums, and mixtures thereof;

c) starches, preferably modified starches, such as those derived, for example, from cereals such as wheat, corn or rice, from legumes such as yellow peas, from tubers such as potatoes or manioc, and tapioca starches; carboxymethylstarch. Examples of starches that may be mentioned include the corn starch Starx 15003 sold by the company Staley, the pregelatinized starch sold under the name Lycatab PGS by the company Roquette; the sodium carboxymethylstarch sold under the reference Explotab by the company Roquette;

d) dextrins, such as dextrin extracted from corn;

e) celluloses such as microcristalline cellulose, amorphous cellulose, and cellulose derivatives, in particular hydroxy(Ci-C₆)alkylcelluloses and carboxy(Ci-C₆)alkylcelluloses, which are in particular crosslinked; mention may in particular be made of methylcelluloses, hydroxyalkylcelluloses, ethylhydroxyethylcelluloses and carboxymethylcelluloses. As examples, mention may be made of the microcrystalline cellulose sold under the name Avicel PH 100 or PH102 by the company FMC Biopolymers;

f) pectins;

g) chitosan and derivatives thereof;

h) anionic polysaccharides other than starch and cellulose derivatives, in particular of biotechnological origin, such as anionic polysaccharide bearing as repeating unit a tetrasaccharide composed of L-fucose, D- glucose and glucuronic acid, such as the product bearing the INCI name Biosaccharide Gum-4 sold under the reference Glycofilm 1 .5P by the company Solabia;

i) soybean polysaccharides,

and mixtures thereof;

- synthetic polymers, such as crosslinked or non-crosslinked polyvinylpyrrolidone, for instance crosslinked polyvinylpyrrolidone, for instance Kollindon CL sold by the company BASF, acrylic acid polymers and salts thereof, for instance crosslinked polyacrylates, such as the product sold by the company Rohm and Haas under the reference Acusol 772, polyacrylamides, crosslinked or non- crosslinked poly(2-acrylamidopropanesulfonic acid) polymers (in particular homopolymers), for instance non-crosslinked poly(2-acrylamidopropanesulfonic acid) (Simugel® EG from the company Seppic), crosslinked poly(2-acrylamido-2- methylpropanesulfonic acid), which is free or partially neutralized with aqueous ammonia (Hostacerin® AMPS from the company Clariant), blends of non- crosslinked poly(2-acrylamido-2-methylpropanesulfonic acid) with hydroxyalkylcellulose ethers or with poly(ethylene oxide)s, as described in patent US 4 540 510; blends of poly(meth)acrylamido(Ci-C₄alkyl)sulfonic acid, which is preferably crosslinked, with a crosslinked copolymer of maleic anhydride and of a (CrC₅)alkyl vinyl ether (Stabileze QM from the company ISF).

The amount of hydrophilic thickeners present in the composition according to the invention may be between 0.01 % and 30% and preferably between 0.1 % and 15% by weight and better still between 0.1 % and 10% by weight relative to the total weight of the composition.

The composition according to the invention may comprise at least one amphiphilic polymer comprising at least one hydrophobic chain.

More especially, if they are present, these amphiphilic polymers are of non-ionic, anionic, cationic or amphoteric type. They are preferably of non-ionic, anionic or cationic nature.

Said amphiphilic polymers comprise, more particularly, as hydrophobic chain, a saturated or unsaturated, aromatic or non-aromatic, linear or branched C₆-C₃₀ hydrocarbon-based fatty chain, attached to optionally one or more oxyalkylene (oxyethylene and/or oxypropylene) units.

Among the cationic amphiphilic polymers comprising a hydrophobic chain are cationic polyurethanes or cationic copolymers comprising vinyllactam and in particular vinylpyrrolidone units.

Even more preferentially, the amphiphilic polymers comprising a hydrophobic chain are of non-ionic or anionic nature.

Examples of hydrophobic-chain non-ionic amphiphilic polymers that may be mentioned, inter alia, include celluloses comprising a hydrophobic chain (Natrosol Plus Grade 330 CS® from the company Aqualon; Bermocoll EHM 100® from the company Berol Nobel; Amercell Polymer HM-1500® from the company Amerchol); hydroxypropyl guars modified with one or more hydrophobic groups (Jaguar XC-95/3®, RE210-18, RE205-1 from the company Rhodia Chimie; Esaflor HM 22® from the company Lamberti); copolymers of vinylpyrrolidone and of hydrophobic-chain monomers (certain products of the Antaron® and Ganex® ranges from the company ISP); copolymers of CrC₆ alkyl (meth)acrylates and of amphiphilic monomers comprising a hydrophobic chain; copolymers of hydrophilic (meth)acrylates and of monomers comprising at least one hydrophobic chain (polyethylene glycol methacrylate/lauryl methacrylate copolymer); polymers with an aminoplast ether backbone containing at least one fatty chain (Pure Thix® from the company Sud-Chemie); polyether polyurethanes, of linear (block structure), grafted or star form, comprising in their chain at least one hydrophilic block and at least one hydrophobic block (as described in the article by G. Fonnum, J. Bakke and Fk. Hansen - Colloid Polym. Sci 271 , 380.389 (1993J; in particular the polyether polyurethane which can be obtained by polycondensation of at least three compounds comprising (i) at least one polyethylene glycol comprising from 150 to 180 mol of ethylene oxide, (ii) a polyoxyethylented stearyl alcohol comprising 100 mol of ethylene oxide and (iii) a diisocyanate, as sold in particular by the company Elementis under the name Rheolate FX 1 100®, which is a polycondensate of polyethylene glycol comprising 136 mol of ethylene oxide, of polyoxyethylented stearyl alcohol comprising 100 mol of ethylene oxide and of hexamethylene diisocyanate (HDI) having a weight- average molecular weight of 30 000 (INCI name: PEG-136/Steareth-100/SMDI Copolymer). Mention may also be made of Rheolate® 205, 208, 204 or 212 from the company Rheox; Elfacos® T210, T212 from the company Akzo).

As examples of anionic amphiphilic polymers comprising at least one hydrophobic chain that may be used in the context of the present invention, mention may be made of crosslinked or non-crosslinked polymers comprising at least one hydrophilic unit derived from one or more ethylenically unsaturated monomers comprising a carboxylic acid function, which is free or partially or totally neutralized, and at least one hydrophobic unit derived from one or more ethylenically unsaturated monomers bearing a hydrophobic side chain, and optionally at least one crosslinking unit derived from one or more polyunsaturated monomers.

Mention may be made in particular of copolymers of (meth)acrylic acid and of Cio-C₃₀ alkyl (meth)acrylates, which are crosslinked or non-crosslinked, such as those described in US 3 915 921 and US 4 509 949, or copolymers of (meth)acrylic acid and of fatty alcohol allyl ethers such as those described in EP 216 479.

In addition, the products Carbopol ETD-2020® and 1382®, Pemulen TR1® and TR2® from the company Goodrich; the methacrylic acid/ethyl acrylate/oxyethylenated stearyl methacrylate copolymer (55/35/10); the (meth)acrylic acid/ethyl acrylate/oxyethylenated behenyl methacrylate 25 EO copolymer; the methacrylic acid/ethyl acrylate/steareth-10 allyl ether crosslinked copolymer, are polymers that are suitable for use in the invention.

If these amphiphilic polymers are present, their content represents from 0.01 % to 30% by weight and preferably from 0.1 % to 10% by weight relative to the weight of the composition.

"Fillers" should be understood as meaning solid particles which are insoluble in the medium of the composition, whatever the temperature at which the composition is manufactured.

The fillers may be colourless and inorganic or organic, of any physical shape (platelet, spherical or oblong) and of any crystallographic form (for example sheet, cubic, hexagonal, orthorhombic, etc.). The fillers may be porous or non- porous.

Fillers that may be mentioned include inorganic fillers such as hydrophobic or hydrophilic silicas, clays other than those mentioned above, ceramic beads, magnesium oxides, aluminium silicates and derivatives thereof, in particular clays, such as mixed silicates of natural or synthetic origin, in particular magnesium aluminium silicates, which are in particular hydrated, natural hydrated aluminium silicates, such as bentonite or kaolin, talc, organic fillers such as Nylon, microspheres based on a copolymer of vinylidene chloride/acrylonitrile/methacrylonitrile containing isobutane, and expanded, such as those sold under the name Expancel 551 DE® by the company Expancel, micronized plant powder (such as the fruit powders from the company Lessonia) or non-micronized plant powder, or alternatively rice grain husk powder, and mixtures thereof.

Among the silicas, mention may also be made in particular of fumed silicas of hydrophilic nature (in particular Aerosil® 90, 130, 150, 200, 300 and 380 from the company Degussa Huls).

Some of the rheology modifiers mentioned above may also play a role in aiding the disintegration of the bleaching composition in compressed form during its use.

Thus, in one particular embodiment, the composition according to the invention comprises at least one disintegration agent chosen from celluloses, in particular microcrystalline cellulose, and cellulose derivatives, crosslinked polyacrylates, crosslinked polyvinylpyrrolidone, soybean polysaccharides, alginates, aluminium silicates and derivatives thereof, and silicas, in particular hydrophilic silicas, and mixtures thereof. Surfactants

The composition according to the invention may advantageously comprise at least one surfactant.

The surfactant(s) may be present in the first and/or the second layer of composition, preferably in the first layer of composition.

The surfactant(s) may be chosen indiscriminantly, alone or as mixtures, from anionic, amphoteric, non-ionic, zwitterionic and cationic surfactants, in particular from anionic and/or non-ionic surfactants.

The surfactants suitable for implementing the present invention are in particular the following:

Among the non-ionic surfactants, mention may be made of alcohols, alpha-diols and alkyl phenols, each of these compounds being polyethoxylated and/or polypropoxylated, and containing at least one hydrocarbon-based chain comprising, for example, from 8 to 30 carbon atoms and preferably from 8 to 18 carbon atoms, the number of ethylene oxide and/or propylene oxide groups possibly ranging in particular from 2 to 200.

Mention may also be made of copolymers of ethylene oxide and propylene oxide, condensates of ethylene oxide and/or of propylene oxide with fatty alcohols; polyethoxylated fatty amides preferably having from 2 to 30 mol of ethylene oxide; oxyethylenated fatty acid esters of sorbitan containing from 2 to 30 mol of ethylene oxide; fatty acid esters of sucrose, fatty acid esters of polyethylene glycol, alkylpolyglycosides, N-alkylglucamine derivatives, etc.

The term "anionic surfactant" is understood to mean a surfactant comprising, as ionic or ionizable groups, only anionic groups. These anionic groups are preferably chosen from the groups C0₂H, C0₂ ^", S0₃H, S0₃ ^", OS0₃H, OS0₃ ^", 0₂P0₂H, O2PO2H- and O2PO2^2". The anionic surfactant(s) that may be used in the compositions of the invention are chosen in particular from alkyl sulfates, alkyl ether sulfates, alkylamido ether sulfates, alkylaryl polyether sulfates, monoglyceride sulfates, alkylsulfonates, alkylamide sulfonates, alkylarylsulfonates, oolefin sulfonates, paraffin sulfonates, alkylsulfosuccinates, alkyl ether sulfosuccinates, alkylamide sulfosuccinates, alkyl sulfoacetates, acylsarcosinates, acylglutamates, alkylsulfosuccinamat.es, acylisethionates and N-acyltaurates, salts of alkyl monoesters and polyglycoside-polycarboxylic acids, acyllactylates, salts of D- galactoside uronic acids, salts of alkyl ether carboxylic acids, salts of alkyl aryl ether carboxylic acids, and salts of alkylamido ether carboxylic acids; or the non-salified forms of all of these compounds, the alkyl and acyl groups of all of these compounds containing from 6 to 24 carbon atoms and the aryl group denoting a phenyl group.

Some of these compounds may be oxyethylenated and then preferably comprise from 1 to 50 ethylene oxide units.

The salts of C₆-C₂4 alkyl monoesters of polyglycoside-polycarboxylic acids may be chosen from C₆-C₂4 alkyl polyglycoside citrates, C₆-C₂4 alkyl polyglycoside- tartrates and C₆-C₂4 alkyl polyglycoside-sulfosuccinates.

When the anionic surfactant(s) are in salt form, it (they) may be chosen from alkali metal salts such as the sodium or potassium salt and preferably the sodium salt, the ammonium salts, the amine salts and in particular amino alcohol salts or the alkaline-earth metal salts such as the magnesium salt.

Examples of amino alcohol salts that may in particular be mentioned include monoethanolamine, diethanolamine and triethanolamine salts, monoisopropanolamine, diisopropanolamine or triisopropanolamine salts, 2- amino-2-methyl-1 -propanol salts, 2-amino-2-methyl-1 ,3-propanediol salts and tris(hydroxymethyl)aminomethane salts.

Use is preferably made of alkali metal or alkaline-earth metal salts, in particular sodium or magnesium salts.

Use is preferably made of (C₆-C₂₄)alkyl sulfates and (C₆-C₂₄)alkyl ether sulfates, which are optionally oxyethylenated, comprising from 2 to 50 ethylene oxide units, and mixtures thereof, in particular in the form of alkali metal salts, alkaline-earth metal salts, ammonium salts or amino alcohol salts. More preferentially, the anionic surfactant(s) is (are) chosen from (C10-20) alkyl sulfates in the form of alkali metal or alkaline-earth metal salts, and in particular sodium lauryl sulfate and sodium cetostearyl sulfate, and mixtures thereof.

The amphoteric or zwitterionic surfactant(s) that may be used in the present invention may in particular be optionally quaternized secondary or tertiary aliphatic amine derivatives, in which the aliphatic group is a linear or branched chain containing from 8 to 22 carbon atoms, said amine derivatives containing at least one anionic group, for instance a carboxylate, sulfonate, sulfate, phosphate or phosphonate group. In particular, mention may be made of (C₈- C₂o)alkylbetaines, sulfobetaines, (C₈-C₂o alkyl)amido(C₃-C₈ alkyl)betaines or (C₈- C₂o alkyl)amido(C₆-C₈ alkyl)sulfobetaines.

Among the optionally quaternized secondary or tertiary aliphatic amine derivatives that can be used, as defined above, mention may also be made of the compounds of respective structures (B1 ) and (B2) below:

Ra-C(0)-NH-CH₂-CH₂-N+(Rb)(Rc)-CH₂C(0)0-, M+, X- (B1 ) in which formula:

^■ Ra represents a C1₀-C30 alkyl or alkenyl group derived from an acid Ra- COOH preferably present in hydrolysed coconut oil, or a heptyl, nonyl or undecyl group;

■ Rb represents a β-hydroxyethyl group; and

Rc represents a carboxymethyl group;

M+ represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine, and

^■ X- represents an organic or inorganic anionic counterion, such as that chosen from halides, acetates, phosphates, nitrates, (CrC₄)alkyl sulfates, (Ci-C₄)alkyl- or (Ci-C₄)alkylarylsulfonates, in particular methyl

- are absent;

in which formula:

B represents the group -CH₂-CH₂-0-X';

B' represents the group -(CH₂)_ZY', with z ^■ X' represents the group -CH₂-C(0)OH, -CH₂-C(0)OZ\ -CH₂-CH₂-C(0)OH or

-CH₂-CH₂-C(0)OZ\ or a hydrogen atom;

^■ Y' represents the group -C(0)OH, -C(0)OZ', -CH₂-CH(OH)-S0₃H or the group -CH₂-CH(OH)-S0₃-Z';

^■ Z' represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine;

^■ Ra' represents a Ci₀-C₃o alkyl or alkenyl group of an acid Ra'-C(0)OH preferably present in coconut oil or in hydrolysed linseed oil, an alkyl group, in particular of Ci₇ and its iso form, or an unsaturated Ci₇ group. These compounds are classified in the CTFA dictionary, 5th edition, 1993, under the names disodium cocoamphodiacetate, disodium lauroamphodiacetate, disodium caprylamphodiacetate, disodium capryloamphodiacetate, disodium cocoamphodipropionate, disodium lauroamphodipropionate, disodium caprylamphodipropionate, disodium capryloamphodipropionate, lauroamphodipropionic acid and cocoamphodipropionic acid.

By way of example, mention may be made of the cocoamphodiacetate sold by the company Rhodia under the trade name Miranol^® C2M Concentrate.

Use may also be made of compounds of formula (B'2):

Ra"-NH-CH(Y")-(CH₂)n-C(0)-NH-(CH₂)n'-N(Rd)(Re)

(B'2)

in which formula:

^■ Y" represents the group -C(0)OH, -C(0)OZ", -CH₂-CH(OH)-S0₃H or the group -CH₂-CH(OH)-S0₃-Z";

^■ Rd and Re, independently of one another, represent a Ci-C₄ alkyl or hydroxyalkyl radical;

^■ Z" represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine;

^■ Ra" represents a Ci₀-C₃₀ alkyl or alkenyl group of an acid Ra"-C(0)OH preferably present in coconut oil or in hydrolysed linseed oil;

^■ n and n' denote, independently of one another, an integer ranging from 1 to 3. Among the compounds of formula (B'2), mention may be made of the compound classified in the CTFA dictionary under the name sodium diethylaminopropyl cocoaspartamide and sold by the company Chimex under the name Chimexane HB.

Among the amphoteric or zwitterionic surfactants mentioned above, use is preferably made of (C₈-C₂o)alkylbetaines such as cocobetaine, (C₈- C2o)alkylamido(C₃-C₈)alkylbetaines such as cocoamidopropylbetaine, and mixtures thereof, and the compounds of formula (B'2) such as the sodium salt of diethylaminopropyl laurylaminosuccinamate (INCI name: sodium diethylaminopropyl cocoaspartamide).

More preferentially, the amphoteric or zwitterionic surfactant(s) is (are) chosen from cocoamidopropylbetaine and cocobetaine, the sodium salt of diethylaminopropyl laurylaminosuccinamate, or mixtures thereof.

The amounts of surfactants present in the composition according to the invention may range from 0.01 % to 30%, preferably from 0.1 % to 20% by weight and better still from 0.5% to 10% by weight relative to the total weight of the composition. Organic inert phase

The composition in accordance with the invention may comprise at least one organic inert phase.

The organic inert phase may be present in the first and/or the second layer of composition.

The term "inert" is understood to mean not causing a rapid destruction of the persulfates, i.e. not causing a decrease in the persulfate level of more than 50% in 24 hours at ambient temperature. Preferably, the organic inert phase is a fatty phase consisting of one or more fatty substances.

The term "fatty substance" is understood to mean an organic compound that is insoluble in water at ordinary temperature (25°C) and at atmospheric pressure (760 mmHg) (solubility of less than 5%, preferably less than 1 % and even more preferentially less than 0.1 %). The fatty substances have in their structure at least one hydrocarbon-based chain containing at least 6 carbon atoms or a sequence of at least two siloxane groups. In addition, the fatty substances are generally soluble in organic solvents under the same temperature and pressure conditions, for instance chloroform, dichloromethane, carbon tetrachloride, ethanol, benzene, toluene, tetrahydrofuran (THF), liquid petroleum jelly or decamethylcyclopentasiloxane. The fatty substances of the invention do not contain any salified carboxylic acid groups.

In particular, the fatty substances of the invention are also not (poly)oxyalkylenated or (poly)glycerolated ethers.

Preferably, the composition comprises a liquid organic inert phase (liquid fatty phase), comprising oils as fatty substances. For the purposes of the present invention, the term "liquid phase" is understood to mean any phase that is capable of flowing at ambient temperature, generally between 15°C and 40°C, and at atmospheric pressure, under the action of its own weight.

The term "o/7" is understood to mean a "fatty substance" that is liquid at ambient temperature (25°C) and at atmospheric pressure (760 mmHg). The organic inert liquid phase can in particular be chosen from the polydecenes of formula Cio_nH[₍20n)+2] in which n ranges from 3 to 9 and preferably from 3 to 7, liquid fatty alcohols, esters of fatty alcohols or of fatty acids, sugar esters or diesters of C12-C24 fatty acids, cyclic ethers or cyclic esters, silicone oils, mineral oils or plant oils, or mixtures thereof.

The compounds of formula CionH_[(20n)+2] in which n ranges from 3 to 9 correspond to the name "polydecene" of the CTFA dictionary, 7th edition, 1997 of the Cosmetic, Toiletry and Fragrance Association, USA, and also to the same INCI name in the USA and in Europe. These are poly-1 -decene hydrogenation products.

Among these compounds, those for which, in the formula, n ranges from 3 to 7 are preferred.

Examples that may be mentioned include the product sold under the name Silkflo® 366 NF Polydecene by the company Amoco Chemical, and those sold under the name Nexbase® 2002 FG, 2004 FG, 2006 FG and 2008 FG by the company Fortum.

As regards the esters of fatty alcohols or of fatty acids, examples that may be mentioned include:

- esters of saturated, linear or branched C₃-C₆ lower monoalcohols with monofunctional C12-C24 fatty acids, these fatty acids possibly being linear or branched, saturated or unsaturated and chosen in particular from oleates, laurates, palmitates, myristates, behenates, cocoates, stearates, linoleates, linolenates, caprates and arachidonates, or mixtures thereof, and in particular oleo-palmitates, oleo-stea rates and palmito-stearates. Among these esters, it is more particularly preferred to use isopropyl palmitate, isopropyl myristate and octyldodecyl stearate,

- esters of linear or branched C₃-C₈ monoalcohols with difunctional C₈-C₂4 fatty acids, these fatty acids possibly being linear or branched, and saturated or unsaturated, for instance the isopropyl diester of sebacic acid, also known as diisopropyl sebacate,

- esters of linear or branched C₃-C₈ monoalcohols with difunctional C₂-C₈ fatty acids, these fatty acids possibly being linear or branched, and saturated or unsaturated, for instance dioctyl adipate and dicaprylyl maleate,

- the ester of a trifunctional acid, for instance triethyl citrate.

As regards the sugar esters and diesters of C12-C24 fatty acids, the term "sugar" is understood to mean compounds containing several alcohol functions, with or without an aldehyde or ketone function, and which comprise at least 4 carbon atoms. These sugars can be monosaccharides, oligosaccharides or polysaccharides.

As sugars that may be used according to the invention, examples that may be mentioned include sucrose (or saccharose), glucose, galactose, ribose, fucose, maltose, fructose, mannose, arabinose, xylose and lactose, and derivatives thereof, in particular alkyl derivatives such as methyl derivatives, for instance methylglucose.

The esters of sugars and of fatty acids that may be used according to the invention may be chosen in particular from the group comprising esters or mixtures of esters of sugars described above and of linear or branched, saturated or unsaturated C12-C24 fatty acids.

The esters may be chosen from mono-, di-, tri-, tetraesters and polyesters, and mixtures thereof.

These esters may be chosen, for example, from oleates, laurates, palmitates, myristates, behenates, cocoates, stearates, linoleates, linolenates, caprates and arachidonates, or mixtures thereof such as, especially, oleo-palmitate, oleo- stearate and palmito-stearate mixed esters.

It is more particularly preferred to use monoesters and diesters and in particular sucrose, glucose or methyl-glucose mono- or dioleates, stearates, behenates, oleopalmitates, linoleates, linolenates and oleo-stearates.

Mention may be made, by way of example, of the product sold under the name Glucate® DO by Amerchol, which is a methylglucose dioleate.

Examples of esters or mixtures of esters of sugar and of fatty acid that may also be mentioned include:

-the products sold under the names F160, F140, F1 10, F90, F70 and SL40 by the company Crodesta, respectively denoting sucrose palmitostearates formed from 73% monoester and 27% diester and triester, from 61 % monoester and 39% diester, triester and tetraester, from 52% monoester and 48% diester, triester and tetraester, from 45% monoester and 55% diester, triester and tetraester, from 39% monoester and 61 % diester, triester and tetraester, and sucrose monolaurate;

-the products sold under the name Ryoto Sugar Esters, for example referenced B370 and corresponding to sucrose behenate formed from 20% monoester and 80% diester, triester and polyester;

-the sucrose monodipalmitostearate sold by the company Goldschmidt under the name Tegosoft^® PSE.

As regards the cyclic ethers and cyclic esters, γ-butyrolactone, dimethyl isosorbide and diisopropyl isosorbide are in particular suitable.

Silicone oils may also be used as inert organic liquid phase.

More particularly, the silicone oils that are suitable are liquid, non-volatile silicone fluids with a viscosity of less than or equal to 10 000 mPa.s at 25°C, the viscosity of the silicones being measured according to ASTM standard 445 Appendix C. Silicone oils are defined in greater detail in Walter Noll's "Chemistry and Technology of Silicones" (1968) - Academic Press.

Among the silicone oils that may be used according to the invention, mention may be made in particular of the silicone oils sold under the names DC-200 Fluid - 5 mPa.s, DC-200 Fluid - 20 mPa.s, DC-200 Fluid - 350 mPa.s, DC-200 Fluid - 1000 mPa.s and DC-200 Fluid - 10 000 mPa.s by the company Dow Corning. Mineral oils may also be used as inert organic liquid phase, for instance liquid paraffin.

Plant oils may also be suitable for use, and in particular avocado oil, olive oil or liquid jojoba wax.

Preferably, the inert organic liquid phase is chosen from the group formed by polydecenes of formula CionH_[(20n)+2] in which n ranges from 3 to 9 and preferably from 3 to 7, and esters of fatty alcohols or of fatty acids, and mixtures thereof. According to one particular embodiment of the invention, the content of organic inert phase, which is preferably liquid, ranges from 0.1 % to 30% by weight, preferably from 0.5% to 20% by weight and even more preferentially from 1 % to 10% by weight relative to the weight of the composition according to the invention. The bleaching composition according to the invention which is in compressed form is preferably anhydrous.

In the context of the present invention, a composition is anhydrous when it has a water content of less than 1 % by weight and preferably less than 0.5% by weight relative to the total weight of the composition. Preferably, the composition according to the invention is free of water.

The composition in accordance with the present invention may also comprise various additives conventionally used in cosmetics and which may be present in the first and/or the second layer of the composition.

The composition in accordance with the present invention may thus comprise lubricants, for instance polyol stearates or alkali metal or alkaline-earth metal stearates, pigments, colouring agents, additives such as urea, ammonium chloride, antioxidants, penetrants, sequestrants such as EDTA or EDDS, buffers, dispersants, film-forming agents, preservatives, opacifiers, vitamins, fragrances, anionic, non-ionic, amphoteric or zwitterionic polymers other than the rheology modifiers already mentioned, conditioning agents, for instance cationic polymers, ceramides and amino silicones. Needless to say, a person 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 composition in accordance with the invention are not, or are not substantially, adversely affected by the envisaged addition(s). In particular, the composition may comprise at least one colouring agent chosen from oxidation dye precursors, direct dyes or mixtures thereof, which will be detailed below. The colouring agent may be present in the first and/or in the second layer. The oxidation dye precursors are generally chosen from oxidation bases, couplers, and mixtures thereof.

By way of example, the oxidation bases are chosen from para- phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols, ortho- aminophenols, heterocyclic bases, for instance pyridine derivatives, pyrimidine derivatives and pyrazole derivatives, and the addition salts thereof.

The composition according to the invention may optionally comprise one or more couplers advantageously chosen from those conventionally used in the dyeing of keratin fibres.

Mention may in particular be made, among these couplers, of meta- phenylenediamines, meta-aminophenols, meta-diphenols, naphthalene-based couplers and heterocyclic couplers, and also the addition salts thereof.

In general, the addition salts of the oxidation bases and couplers that can be used within the context of the invention are in particular chosen from the addition salts with an acid such as the hydrochlorides, hydrobromides, sulfates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, phosphates and acetates.

The oxidation dye precursor(s) each advantageously represent(s) from 0.0001 % to 10% by weight relative to the total weight of the composition, and preferably from 0.005% to 5% by weight relative to the total weight of the composition. The term "direct dye" is understood to mean natural and/or synthetic dyes, different from oxidation dyes and which therefore have an intrinsic colouring power, i.e. not requiring a chemical conversion in order to colour. The direct dye may be chosen from neutral (non-ionic), acidic (or anionic) and basic (or cationic) dyes, and mixtures thereof.

Examples of suitable direct dyes that may be mentioned include azo direct dyes; methine direct dyes; carbonyl direct dyes; azine direct dyes; nitro(hetero)aryl direct dyes; tri(hetero)arylmethane direct dyes; porphyrin direct dyes; phthalocyanine direct dyes, and natural direct dyes, alone or as mixtures.

The direct dye(s) may represent from 0.0001 % to 10% by weight, relative to the total weight of the composition, and preferably from 0.005% to 5% by weight.

The first and second layers present in the composition in compressed form may have different colours.

The composition in compressed form may be obtained according to known compression or compacting (or pelleting) processes, for instance direct compression. The composition may in particular be provided in the form of a powder that is compacted, for example in a pelletizer, by application of a compression force. The value of the compression force may range, for example, from 0.1 to 500 MPa and in particular from 0.2 to 100 MPa.

Apart from the first and the second layer, the composition in compressed form according to the invention may comprise at least one additional layer distinct from the first and second layers.

Thus, according to one embodiment, it may comprise, between the first layer and the second layer, a separation layer comprising compounds that are chemically inert with respect to the persulfate present in the first layer and with respect to the hydrogen peroxide generator present in the second layer.

Preferably, the first and second layers of the composition in compressed form are outer layers. More preferably, the composition in compressed form does not comprise a separation layer. According to one embodiment, the composition according to the invention may comprise, besides the first and second layers, at least one layer comprising breakdown agents intended to accelerate the disintegration of the tablet, alkaline agents as mentioned above, and cosmetic active agents, and mixtures thereof. Breakdown agents that may in particular be mentioned include celluloses and cellulose derivatives, in particular hydroxyalkylcelluloses, amphiphilic polyurethanes, crosslinked polyacrylates, crosslinked polyvinylpyrrolidone, gums, such as guar gum, soybean polysaccharides, alginates, aluminium silicates and derivatives thereof, and silicas, in particular hydrophilic silicas, and mixtures thereof.

According to one embodiment, the composition in compressed form may comprise at least one inclusion, for example in bead form, comprising a powder or a liquid encapsulated in a water-soluble film. All the optional ingredients mentioned above may be present in the first and/or the second layer and/or the additional layer(s), if present, of the composition in compressed form.

The composition in compressed form according to the invention may be in a ready-to-use single-dose form. According to one embodiment, it may be splittable and may comprise on at least one of its faces at least one splitting bar indicating a division of the tablet into two parts (for example two halves) or several parts, in order to enable metering of the amount of bleaching composition to be used in the process.

The composition in compressed form according to the invention may be conditioned in individual form or grouped in a hermetic, moisture-proof sachet.

The present invention also relates to a process for bleaching keratin fibres, which consists in applying to the keratin fibres a bleaching composition which is in compressed form, comprising at least one first layer comprising at least one persulfate and at least one second layer comprising at least one hydrogen peroxide generator, in the presence of an aqueous composition. The composition in compressed form is generally added to the aqueous composition just at the time of use, i.e. just before application to the keratin fibres. The step of dissolution of the bleaching composition in compressed form may take a few seconds to a few minutes, and may be performed with or without stirring.

The suitable medium for the aqueous composition generally consists of water or a mixture of water and at least one organic solvent to dissolve the compounds that are not sufficiently water-soluble. Examples of organic solvents that may be mentioned include Ci-C₄ lower alkanols, such as ethanol and isopropanol; polyols such as propylene glycol, glycerol, dipropylene glycol and polyol ethers, for instance 2-butoxyethanol, propylene glycol monomethyl ether, and also aromatic alcohols, for instance benzyl alcohol or phenoxyethanol, similar products and mixtures thereof.

The solvents may be present in proportions preferably of between 1 % and 40% by weight and more preferably still between 5% and 30% by weight approximately relative to the total weight of the aqueous composition.

Preferably, the aqueous composition is constituted of water.

The aqueous composition may be in any form suitable to allow good dilution of the composition in compressed form, preferably in liquid form.

The composition may also contain various additives conventionally used in cosmetics, such as those described previously.

It may also comprise agents for controlling the release of oxygen, such as magnesium carbonate or oxide.

The additives and the oxygen-release control agents as defined previously may be present in an amount, for each of them, of between 0.01 % and 40% by weight and preferably between 0.1 % and 30% by weight relative to the total weight of the aqueous composition. The invention will be illustrated more fully with the aid of the non-limiting examples that follow. Unless otherwise mentioned, the amounts indicated are expressed in grams. EXAMPLE

The following bleaching composition in powder form can be prepared:

Lozenges of 10 g each can be prepared from the obtained powder using a Specac compacting machine.

The resulting composition in lozenge form can be mixed with an aqueous composition in a ratio of 1/1 .5 to 1/2, i.e. 4 lozenges (40 g) for 60 to 80 g of water. In contact with water, the urea peroxide generates hydrogen peroxide.

Claims

Composition for bleaching keratin fibres, which is in compressed form, comprising at least one first layer comprising at least one persulfate and at least one second layer comprising at least one hydrogen peroxide generator.

Composition according to Claim 1 , in which the persulfate(s) is (are) chosen from sodium persulfates, potassium persulfates and ammonium persulfates, and mixtures thereof.

Composition according to Claim 1 or 2, characterized in that the persulfate concentration is between 10% and 80% by weight, preferably between 20% and 70% by weight and better still between 40% and 65% by weight relative to the total weight of the composition.

Composition according to any one of the preceding claims, characterized in that the hydrogen peroxide generator is chosen from:

polymeric complexes that can release hydrogen peroxide, such as polyvinylpyrrolidone/H₂0₂,

urea peroxide, alkali metal, alkaline-earth metal or ammonium perborates and percarbonates, in particular the percarbonates, and mixtures thereof.

Composition according to any one of the preceding claims, characterized in that the hydrogen peroxide generator is chosen from alkali metal or alkaline- earth metal percarbonates, in particular sodium percarbonate.

Composition according to any one of the preceding claims, characterized in that the hydrogen peroxide-generating agent(s) represent(s) from 0.1 % to 40% by weight, preferably from 0.5% to 20% by weight and better still from 1 % to 10% by weight relative to the total weight of the composition.

Composition according to any one of the preceding claims, characterized in that it comprises at least one alkaline agent chosen from water-soluble silicates such as alkali metal or alkaline-earth metal silicates, dibasic or tribasic alkali metal or alkaline-earth metal phosphates, and alkali metal or alkaline-earth metal carbonates, and mixtures thereof.

8. Composition according to the preceding claim, characterized in that the alkaline agent(s) is (are) present in an amount ranging from 0.1 % to 40%, preferably from 0.5% to 30% by weight and better still from 1 % to 20% by weight relative to the total weight of the composition.

9. Composition according to any one of the preceding claims, characterized in that it comprises at least one rheology modifier chosen from hydrophilic thickeners, amphiphilic polymers comprising at least one hydrophobic chain, and fillers, and mixtures thereof.

10. Composition according to any one of the preceding claims, characterized in that it comprises at least one disintegration agent chosen from celluloses and cellulose derivatives, crosslinked polyacrylates, crosslinked polyvinylpyrrolidone, soybean polysaccharides, alginates, aluminium silicates and derivatives thereof, and hydrophilic silicas, and mixtures thereof.

1 1 . Composition according to any one of the preceding claims, characterized in that it comprises an organic inert phase, which is preferably liquid, preferably chosen from the group formed by the polydecenes of formula CionH_[(20n)+2] in which n ranges from 3 to 9 and preferably from 3 to 7, and esters of fatty alcohols or of fatty acids, and mixtures thereof.

12. Composition according to any one of the preceding claims, characterized in that it comprises at least one surfactant, preferably an anionic or non-ionic surfactant.

13. Process for bleaching keratin fibres, which consists in applying to the keratin fibres a composition according to one of Claims 1 to 12, in the presence of an aqueous composition.