阅读说明：本技术 使用带有至少一种氧化染料的基底、多种防腐剂和氧化水性组合物的氧化染色方法 (Oxidative dyeing process using a substrate carrying at least one oxidation dye, a plurality of preservatives and an oxidizing aqueous composition ) 是由 亨利·萨曼 塞德里克·特鲁什 于 2018-12-21 设计创作，主要内容包括：使用带有至少一种氧化染料的基底、多种防腐剂和氧化水性组合物的氧化染色方法。本发明涉及一种用于氧化染色角蛋白纤维、特别是人角蛋白纤维如头发的方法,包括向所述角蛋白纤维施用i)基底的步骤,该基底在其表面上包含一种或多种氧化染料、一种或多种硫醇化还原剂以及一种或多种还原酮类型的有机还原剂；以及向所述角蛋白纤维施用ii)氧化水性组合物的步骤,该氧化水性组合物包含一种或多种氧化剂。本发明还涉及一种用于制备所述基底的方法。本发明还涉及一种片材形式的元件,该元件通过组合物预处理,该组合物包含一种或多种氧化染料、一种或多种硫醇化还原剂和一种或多种还原酮类型的有机还原剂。(Oxidative dyeing process using a substrate carrying at least one oxidation dye, a plurality of preservatives and an oxidizing aqueous composition. The present invention relates to a process for the oxidation dyeing of keratin fibres, in particular human keratin fibres such as the hair, comprising the step of applying to said keratin fibres i) a substrate comprising, on its surface, one or more oxidation dyes, one or more mercaptanized reducing agents and one or more organic reducing agents of the reducing ketone type; and a step of applying ii) an oxidizing aqueous composition comprising one or more oxidizing agents to the keratin fibers. The invention also relates to a method for preparing said substrate. The invention also relates to an element in sheet form, pretreated by a composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type.)

1. A process for the oxidation dyeing of keratin fibres, in particular human keratin fibres such as the hair, comprising:

i) a step of applying to the keratin fibres a substrate comprising a surface coated with at least one layer constituted by a dye composition comprising:

-one or more oxidation dyes;

one or more thiolating reducing agents, and

-one or more organic reducing agents of the reducing ketone type; and

ii) a step of applying to the keratin fibres an oxidizing aqueous composition comprising one or more chemical oxidizing agents;

it is understood that the total water content of the dye composition is less than 20% by weight relative to the total weight of the dye composition.

2. The method of claim 1, wherein the substrate is an element in the form of a sheet.

3. The method according to claim 2, characterized in that the element in sheet form is made of: plastic material, in particular thermoplastic, paper, metal, in particular aluminum, woven fabric, nonwoven fabric of non-absorbent fibres, in particular of cellulose or derivatives thereof, or polyamide 6, 6.

4. A method according to claim 2 or 3, characterized in that said element in sheet form comprises an adhesive layer on which one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type are deposited.

5. Process according to any one of claims 1 to 4, characterized in that the oxidation dye is chosen from oxidation bases and optionally couplers and preferably comprises at least one oxidation base and at least one coupler.

6. Process according to claim 5, characterized in that the oxidation base is chosen from p-phenylenediamine, bisphenylalkylenediamine, p-aminophenol, o-aminophenol and heterocyclic bases, and addition salts thereof, and in particular from p-phenylenediamine, 1-methyl-2, 5-diaminobenzene, p-aminophenol, 1-hydroxyethyl-4, 5-diaminopyrazole sulphate and 2, 3-diaminodihydroxypyrazolone dimethylsulphonate, and addition salts thereof, and mixtures thereof.

7. Process according to claim 5, characterized in that the couplers are chosen from meta-phenylenediamines, meta-aminophenols, meta-diphenols, naphthalene-based couplers and heterocyclic couplers, and also addition salts thereof, and is in particular selected from resorcinol, 2-methylresorcinol, 5-N- (β -hydroxyethyl) amino-2-methylphenol, 2-methyl-5-aminophenol, 1- β -hydroxyethyloxy-2, 4-diaminobenzene dihydrochloride, 3-aminophenol, (5-N-hydroxyethyl) amino-o-cresol, 5-amino-o-cresol and 1- β -hydroxyethyloxy-2, 4-diaminobenzene dihydrochloride, addition salts thereof and mixtures thereof.

8. The process according to any one of the preceding claims, characterized in that the thiolated reducing agent is selected from those of formula i-1, and also organic or inorganic acid or base salts thereof, optical isomers thereof and tautomers thereof, and solvates such as hydrates; and/or mixtures thereof:

R-SH

i-1

in said formula i-1:

r represents:

-linear or branched (C)₁-C₈) Alkyl, preferably (C)₁-C₆) Alkyl, optionally substituted, preferably by one or more groups selected from carboxyl groups C (O) OH, (di) (C₁-C₄) (alkyl) amino, hydroxy-OH, mercapto-SH; and/or optionally interrupted by one or more heteroatoms or groups selected from: -O-, -S-, -N (R ' "), C (O), or a combination thereof, such as-O-C (O) -, -C (O) -O-, -N (R '") -C (O) -, or-C (O) -N (R ' ") -; wherein R' "represents a hydrogen atom or (C)₁-C₆) An alkyl group; or

- (hetero) aryl optionally substituted, in particular, by one or more hydroxyl, mercapto or carboxyl groups.

9. Process according to any one of the preceding claims, characterized in that the thiolated reducing agent is chosen from those of formula i-1 as defined in the preceding claim, and also organic or inorganic acid or base salts thereof, optical isomers thereof and tautomers thereof, and solvates thereof, such as hydratesAn agent; and/or mixtures thereof, wherein R represents linear or branched (C)₁-C₈) Alkyl, preferably (C)₁-C₆) An alkyl group, a carboxyl group,

-it is substituted with one or more groups selected from: carboxyl C (O) OH, amino, hydroxyl-OH and mercapto-SH; and/or

-it is optionally interrupted by one or more heteroatoms or groups selected from: -O-, -N (R ' "), C (O), or combinations thereof, such as-O-C (O) -, -C (O) -O-, -N (R '") -C (O) -, or-C (O) -N (R ' "), wherein R '" represents a hydrogen atom or (C (R ' "))₁-C₆) Alkyl, preferably R represents straight or branched, non-interrupted (C)₁-C₈) Alkyl, more preferably (C)₁-C₆) An alkyl group.

10. The process according to any one of claims 1 to 8, characterized in that the thiolated reducing agent is selected from those of formula i-1 as defined in claim 8, and also organic or inorganic acid or base salts thereof, optical isomers thereof and tautomers thereof, and solvates thereof, such as hydrates; and/or mixtures thereof, wherein R represents:

-phenyl optionally substituted with one or more hydroxyl, thiol or carboxyl groups; or

-a 5-to 10-membered, preferably 9-or 10-membered bicyclic heteroaryl group comprising 1 to 4 heteroatoms selected from O, S or N, preferably N, optionally substituted with one or more hydroxyl or mercapto groups.

11. The method according to any one of the preceding claims, characterized in that the thiolating reducing agent is selected from thioglycolic acid, thiolactic acid, cysteine, cysteamine, homocysteine, glutathione, thioglycerol, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiodiglycol, 2-mercaptoethanol, dithiothreitol, N-acetylcysteine, esters and amides of thioglycolic acid or thiolactic acid, in particular glycerol monothioglycolate; and also organic or inorganic acid or base salts thereof, optical isomers and tautomers thereof, and solvates such as hydrates; and mixtures of these compounds; preferably selected from thioglycolic acid, thiolactic acid, cysteamine and also organic or inorganic acid or base salts thereof, optical isomers and tautomers thereof, and solvates such as hydrates, and mixtures thereof; preferably selected from thioglycolic acid, thiolactic acid and mixtures thereof.

12. Process according to any one of the preceding claims, characterized in that the thiolated reducing agent is present in a total amount ranging from 0.5% to 60% by weight, preferably from 1% to 50% by weight, more preferably from 4% to 45% by weight and better still from 10% to 40% by weight, relative to the total weight of the dye composition.

13. Process according to any one of the preceding claims, characterized in that the organic reducing agent of the reductone type is chosen from those of general formula (IX) and also salts thereof; and/or mixtures thereof:

in the formula

R₁And R₂Each independently of the others, represents a group containing at least one carbon and/or oxygen atom, R₁And R₂Possibly forming a ring, preferably 5-or 6-membered, with three carbon atoms of the compound of formula (IX), the further constituent atoms of said ring being constituted by carbon and/or oxygen atoms.

14. Process according to any one of the preceding claims, characterized in that the organic reducing agent of the reductone type is chosen from those of formula (IX) as defined in the preceding claim, and also salts thereof and/or mixtures thereof, wherein R₁And R₂With three carbon atoms of the compound of formula (IX) to form a 5-membered ring, the further constituent atoms of which are composed of carbon and/or oxygen atoms; preferably, the compound of formula (IX) is a lactone.

15. The process according to any one of the preceding claims, characterized in that the organic reducing agent of the reducing ketone type is selected from reducing acids, ascorbic acid, erythronic acid or isoascorbic acid, and also salts thereof, such as sodium or potassium salts, ascorbyl palmitate and/or mixtures thereof.

16. Process according to any one of the preceding claims, characterized in that the organic reducing agent of the reductone type is present in a total amount ranging from 0.5% to 50% by weight, preferably from 1% to 45% by weight, more preferably from 4% to 35% by weight and better still from 8% to 30% by weight, relative to the total weight of the dye composition.

17. Method according to any one of the preceding claims, characterized in that the dye composition comprising the oxidation dye, the thiolated reducing agent and the organic reducing agent of the reduced ketone type is present on a portion of the surface of the substrate and exhibits a pattern having a desired shape.

18. Method according to any one of the preceding claims, characterized in that the substrate comprises a copy of the desired pattern on the side opposite to the side carrying the oxidation dye, the thiolated reducing agent and the organic reducing agent of the reduced ketone type.

19. Method according to any one of the preceding claims, characterized in that the surface of the substrate comprises one or more patterns before the deposition of the oxidation dye, the thiolated reducing agent and the organic reducing agent of the reduced ketone type.

20. The method of any of the preceding claims, wherein the substrate is transparent.

21. The method of any one of the preceding claims, wherein the substrate further comprises one or more alkaline agents on its surface.

22. The method according to any of the preceding claims, characterized in that the substrate further comprises on its surface one or more additional antioxidant active agents, preferably selected from sulfites, bisulfites such as ammonium bisulfite and alkali or alkaline earth metal bisulfites such as for example sodium bisulfite, sulfinates; more preferably, the additional antioxidant active is present in an amount ranging from 0.5% to 10% by weight relative to the total weight of the dye composition.

23. The method as claimed in any one of the preceding claims, characterized in that said oxidizing aqueous composition comprises one or more chemical oxidizing agents selected from hydrogen peroxide and/or peroxygenated salts.

24. The method according to any one of the preceding claims, characterized in that the oxidizing aqueous composition further comprises one or more alkaline agents and/or one or more colorants, such as couplers.

25. The method according to any one of the preceding claims, characterized in that it comprises applying the oxidizing aqueous composition as described in any one of claims 1, 23 and 24 to keratin fibres, and then applying the substrate as described in any one of claims 1 to 22 to said fibres.

26. Process for producing a substrate as defined in any one of claims 1 to 22, characterized in that it comprises at least one step of depositing on the surface of the substrate at least one dye formulation composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type; and at least one step of drying said substrate; preferably, the step of depositing on the surface of the substrate comprises depositing said dye formulation composition by a printing process.

27. Method according to the preceding claim, characterized in that the printing method is a screen printing method, a flexographic printing method, an offset printing method, an inkjet printing method or a laser printing method.

28. An element in sheet form, pretreated on its surface by a dye preparation composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the vat ketone type; the oxidation dye, the thiolated reducing agent, and the organic reducing agent of the reduced ketone type are printed on the sheet-form element.

29. Element in sheet form according to the preceding claim, characterized in that it is selected from a plastic sheet covered with a paper layer having a thickness of less than 50 μ ι η or a hydrophilic material layer having a thickness in the range 5 to 200 μ ι η.

30. The sheet-form element of claim 28, wherein the element is selected from a microcellular sheet in which the cells are spaced from one another by a plastic material.

Technical Field

The present invention relates to a process for the oxidation dyeing of keratin fibres, in particular human keratin fibres such as the hair, comprising: applying to the keratin fibres i) a substrate comprising, on its surface, one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type; and a step of applying ii) an oxidizing aqueous composition to the keratin fibres, the oxidizing aqueous composition comprising one or more oxidizing agents.

The invention also relates to a method for preparing said substrate.

The invention also relates to an element in sheet form, pretreated by a composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type.

Background

Standard oxidation dyeing processes generally consist in bringing a mixture comprising an oxidation base or an oxidation base and a coupler with hydrogen peroxide (H)₂O₂Or aqueous hydrogen peroxide) (as oxidizing agent) onto keratin fibres, in that it is allowed to diffuse and then in that the fibres are rinsed. The colourations produced therefrom are generally permanent, vivid and resistant to external agents, in particular to light, inclement weather, washing, perspiration and rubbing.

However, it has been found that it is often difficult or even impossible to obtain colourings with novel visual results by means of "standard" oxidation dyeing techniques. In particular, these methods do not make it possible to satisfactorily obtain coloured patterns which can lead to novel optical effects on the whole head of hair and which are both clear and precise.

These standard oxidation dyeing methods also have the following drawbacks: the hands of the user or colorist are stained during the application of the ready-to-use composition resulting from mixing the dye composition with the oxidizing composition onto the hair. Similarly, this type of method may also cause undesirable stains on the scalp, the contours of the face and/or the clothing of the user, which may be due to application errors and/or flow problems of these compositions.

These standard oxidation dyeing methods also entail the risk of not leading to the final coloration desired by the user, either because of errors during the handling of these dye compositions and oxidizing compositions or because of poor selection of these starting dye compositions.

It has also been found that storage of the dye compositions and oxidizing compositions for obtaining the desired coloration can cause space-occupying problems, especially in hair styling salons.

These oxidation dyeing methods may therefore prove impractical for achieving many different colors depending on the user.

Furthermore, it is known from document FR 3015895 to carry out a dyeing process comprising contacting keratin fibres with a substrate pretreated with one or more oxidation dyes and with an oxidizing aqueous composition. The oxidation dye present on the surface of the substrate dissolves and reacts with the oxidizing agent, contacting the fibers to dye them, which results in a pattern that may be uniform in coloration and/or result in coloration.

However, the dyeing process described in this document is not entirely satisfactory in terms of preserving the substrate. In fact, it has been noted that the dyeing power of the oxidation dyes present on the substrate is greatly reduced within a few days due to the effect of atmospheric oxygen. However, it is very common for a user to wait one or more months before using the coloring product.

Therefore, there is a real need to implement a process for the oxidation dyeing of keratin fibres, in particular human keratin fibres such as the hair, comprising contacting the keratin fibres with a substrate pretreated with one or more oxidation dyes and with an oxidizing aqueous composition, in which the substrate is preserved satisfactorily; that is, effective dyeing power can be retained even when the method is performed several weeks after the substrate is prepared.

This method must also be free from the drawbacks mentioned previously, namely that it is in particular capable of producing colorations on the fibres that may be uniform and/or that may have novel visual results, in particular precise coloration patterns, of reducing the problems of space occupation of the composition used, of minimizing the risks of contact that may occur between the composition used and the hands, scalp and/or clothing of the user, and of minimizing the risks of not obtaining the desired coloration.

Disclosure of Invention

This object is achieved by the present invention, the subject of which is in particular a process for the oxidation dyeing of keratin fibres, in particular human keratin fibres such as the hair, comprising:

i) a step of applying to the keratin fibres a substrate comprising a surface coated with at least one layer constituted by a dye composition comprising:

-one or more oxidation dyes;

one or more thiolating reducing agents, and

-one or more organic reducing agents of the reducing ketone type; and

ii) a step of applying to the keratin fibres an oxidizing aqueous composition comprising one or more chemical oxidizing agents;

it is understood that the total water content of the dye composition is less than 20% by weight relative to the total weight of the dye composition.

It was therefore surprisingly observed that the dyeing process makes it possible to obtain intense colorations even after the dyeing process has been carried out several weeks after the preparation of the substrate.

This is because the process uses a substrate which is easy to store when it is brought into contact with atmospheric oxygen.

The process for dyeing keratin fibres thus uses a substrate on which are deposited one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type. In other words, the substrate has been pretreated at its surface by a dye preparation composition containing one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the vat ketone type.

In particular, the dye composition is present on the surface of the substrate and may be positioned somewhere on said surface so as to represent one or more geometrical forms, so as to produce one or more coloured patterns on said keratin fibres, said pretreated substrate and said oxidizing aqueous composition, after subsequent contact between said fibres. In other words, the substrate may be pretreated in places with a dye formulation composition containing one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reduced ketone type so as to be able to produce one or more coloured patterns on the fibres.

The dyeing process according to the invention thus makes it possible to produce visually sharp coloured patterns on these keratin fibres with good precision. In particular, this method makes it possible to produce millimetre-sized coloured patterns with all types of forms (such as dots or waves) which are easily repeatable. Of course, when these patterns are repeated over the entire head of hair, they can therefore produce novel optical effects.

In other words, the dyeing process according to the invention makes it possible to obtain a pattern, in particular a pattern of millimetre dimensions, uniformly over the whole head of hair or in a localised manner over a portion of said head of hair. These patterns may be imaginative from an aesthetic point of view or may be used to hide irregularities in the colour or appearance of the keratin fibres, especially in the case of regrowth or fading of the ends.

Furthermore, by using a substrate comprising one or more oxidation dyes, i.e. a substrate pretreated with a composition comprising such dyes, this method makes it possible to reduce the risk of staining on the hands, scalp, face and/or clothes of the user. In particular, this method makes it possible to avoid problems of flow and/or application errors of the dye compositions and of the oxidizing compositions.

Similarly, by means of applying such pretreated substrates, this method makes it possible to reduce the storage problems of the dye compositions and oxidizing compositions used in standard methods, and thus makes it possible to reduce the problems of space occupation. In particular, while conserving space in the hair styling salon, the user is free to handle larger amounts of substrate pre-treated with oxidation dyes.

The oxidation dyeing method according to the invention also has the following advantages: the risk of errors that may occur during the treatment of these dye compositions and oxidizing compositions or in the selection of the starting dye composition is minimized to obtain the desired coloration.

The oxidation dyeing process according to the invention also makes it possible to obtain patterns which are bright-colored and/or whose coloration is slightly selective and resistant to external agents, such as shampoos, light, perspiration or bad weather.

In particular, the dyeing process according to the invention leads to the production of patterns whose coloration is vivid and resistant to shampooing.

The present invention also relates to a process for producing a substrate as defined previously, comprising at least one step of depositing on the surface of said substrate at least one dye formulation composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type; and at least one step of drying the substrate.

The invention also relates to an element in the form of a sheet, said element being pretreated on its surface by a dye preparation composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reductone type.

In other words, another subject of the invention relates to an element in sheet form comprising a surface coated with at least one layer consisting of a dye composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the vat ketone type.

In particular, the element in sheet form comprises one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reducing ketone type, which have been deposited on its surface.

The element in sheet form according to the invention has the advantage of being easy to apply to the hair lock. In particular, such an element can be placed horizontally with high precision in a position where it is desired to produce said colored pattern on a lock of hair.

Such an element in sheet form has the advantage of being able to be stored easily in the user's home when compared with the use of dye compositions used in standard oxidation dyeing processes, thus making it possible to reduce the space occupation considerably.

Furthermore, the elements in sheet form may be prepared directly or beforehand in the hair styling salon.

Detailed Description

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

For purposes of the present invention and unless otherwise indicated:

"heteroaryl" denotes a fused or non-fused, optionally cationic, 5-to 22-membered monocyclic or polycyclic group which contains 1 to 6 heteroatoms selected from nitrogen, oxygen, sulfur and selenium atoms, and of which at least one ring is aromatic; preferably, the heteroaryl group is selected from acridinyl, benzimidazolyl, benzoditriazolyl, benzopyrazolyl, pyridazinyl, benzoquinolinyl, benzothiazolyl, benzotriazolyl, benzoxazolyl, pyridyl, tetrazolyl, dihydrothiazolyl, imidazopyridinyl, imidazolyl, indolyl, isoquinolinyl, naphthoimidazolyl, naphthoxazolyl, naphthopyrazolyl, oxadiazolyl, oxazolyl, oxazolopyridinyl, phenazinyl, phenoxazolyl, pyrazinyl, pyrazolyl, pyranyl (pyrilyl), pyrazolyl triazolyl (pyrazolyltriazyl), pyridyl, pyridoimidazolyl, pyrrolyl, quinolinyl, tetrazolyl, thiadiazolyl, thiazolyl, thiazolopyridyl (thiazolylpyridyl), thiazolyl imidazolyl, thiopyranyl (thiopyrryl), triazolyl, xanthinyl or thioxanthyl;

an "aryl" group represents a fused or non-fused, monocyclic or polycyclic, carbon group containing from 6 to 22 carbon atoms, at least one of the rings being aromatic; preferably, aryl is phenyl, biphenyl, naphthyl, indenyl, anthryl or tetrahydronaphthyl;

the "aryl" or "heteroaryl" group or the aryl or heteroaryl part of the group may be substituted by at least one substituent carried by a carbon atom, said substituent being selected from:

-C₁-C₆and is preferably C₁-C₄Alkyl, optionally substituted with one or more groups selected from: hydroxy, C₁-C₂Alkoxy radical, C₂-C₄(poly) hydroxyalkoxy, amido, di-C₁-C₄Alkyl-substituted amino, the two C₁-C₄The alkyl groups may be the same or different, optionally carrying at least one hydroxyl group, or both groups may form, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5-to 7-and preferably 5-or 6-membered heterocyclic ring, optionally containing another nitrogen or non-nitrogen heteroatom;

-a halogen atom;

-a hydroxyl or thiol group;

-C₁-C₆alkoxy or C₁-C₆An alkylthio group;

- (poly) hydroxy (C)₂-C₆) An alkoxy group;

-an amino group;

-a 5-or 6-membered heterocycloalkyl, preferably morpholinyl, piperazinyl, piperidinyl or pyrrolidinyl (pyrolidino), optionally substituted by (C)₁-C₄) Alkyl, preferably methyl;

-a 5-or 6-membered heteroaryl, preferably imidazolyl, optionally substituted by (C)₁-C₄) Alkyl, preferably methyl;

by one or two identical or different C₁-C₆Alkyl-substituted amino, optionally bearing at least:

a hydroxyl group(s),

c optionally substituted by one or two₁-C₃Alkyl-substituted amino, said alkyl possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5-to 7-membered heterocyclic ring, said heterocyclic ring optionally containing at least one other nitrogen or non-nitrogen heteroatom,

quaternary ammonium group-N⁺R'R”R”',M^-Wherein R ', R ' and R ', which may be the same or different, represent a hydrogen atom or C₁-C₄Alkyl radical, and M^-Represents an anionic counter-ion, and is represented by,

or, optionally cationic, 5-or 6-membered heteroaryl, preferably imidazolium, optionally substituted by (C)₁-C₄) Alkyl, preferably methyl;

-amido (-N (R) -C (O) -R'), wherein the R group is a hydrogen atom or C optionally bearing at least one hydroxyl group₁-C₄Alkyl, and the R' group is C₁-C₂An alkyl group;

carbamoyl ((R)₂N-C (O) -, in which the R groups, which may be identical or different, represent a hydrogen atom or a C optionally bearing at least one hydroxyl group₁-C₄An alkyl group;

-alkylsulfonylamino (R' -S (O)₂-N (R) -, in which the R group represents a hydrogen atom or a C optionally bearing at least one hydroxyl group₁-C₄An alkyl group, a carboxyl group,and the radical R' represents C₁-C₄Alkyl or phenyl;

-aminosulfonyl ((R)₂N-S(O)₂-) in which the R groups, which may be identical or different, represent a hydrogen atom or a C optionally bearing at least one hydroxyl group₁-C₄An alkyl group;

-a carboxylic group in acid or salified form (preferably salified with an alkali metal or a substituted or unsubstituted ammonium);

-a cyano group;

-nitro or nitroso;

-polyhaloalkyl, preferably trifluoromethyl;

the nonaromatic part of the cyclic or heterocyclic radical or of the aryl or heteroaryl radical may also be substituted by one or more oxo groups;

the "alkyl radical" being based on a straight-chain or branched C₁-C₁₀In particular C₁-C₈More particularly C₁-C₆And preferably C₁-C₄A hydrocarbon group;

the limits of the ranges of values are included in the range, in particular in the expressions "between" and "ranging from.. to.";

the expression "at least one" is equivalent to and can be replaced by the expression "one or more".

Dyeing method

As indicated previously, the oxidation dyeing process uses, on the keratin fibres, a substrate comprising a surface coated with at least one layer consisting of a dye composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the vat ketone type.

The substrate may be in the form of a sheet or in the form of an element of another implementation.

According to a preferred embodiment, the substrate is an element in the form of a sheet.

The element in sheet form may be made of: plastic material, in particular thermoplastic, paper, metal, in particular aluminum, woven fabric, nonwoven fabric of non-absorbent fibres, in particular of cellulose or derivatives thereof, or polyamide 6, 6.

Preferably, said element in sheet form is a sheet of: plastic materials, in particular thermoplastics, or nonwoven materials of non-absorbent fibres, in particular based on cellulose or derivatives thereof.

In particular, the element in sheet form used in the dyeing process is a plastic sheet.

The element in sheet form may consist of a water-soluble material, which makes it possible to remove it, for example by washing the hair.

Preferably, the element in sheet form comprises an assembly of a layer of water-soluble material and a layer of water-insoluble material (e.g. aluminium foil).

The substrate may be designed to be able to close around a lock of hair. In this case, such a substrate is provided, for example, with a fastening means for holding it in this state, such as an adhesive or a mechanical attachment relief (mechanical attachment relief) disposed near an edge.

Preferably, said element in sheet form has a range of 20g/m²To 300g/m²And even more preferably in the range of 30g/m²To 200g/m²Basis weight of (c).

The elements in sheet form have in particular a thickness ranging from 40 to 1000 microns, preferably ranging from 40 to 400 microns and better still from 60 to 200 microns.

The elements in sheet form may be opaque or transparent. Preferably, said element in sheet form is transparent, which facilitates its positioning on the hair, in particular when it is desired to produce one or more patterns in a precise place on a lock or on the whole hair. In other words, the transparency of the element in sheet form facilitates the implementation of the dyeing process, in particular in the production of coloured patterns, and improves the precision thereof.

The element in sheet form used in the dyeing method according to the invention is preferably flexible and strong. Preferably, the strength of the sheet is greater than 300kPa (Standard TAPPI-T403).

Preferably, said element in sheet form is waterproof. In particular, the water absorption of the element is measured by the COBB60 test, which corresponds to the capacity of the element to absorb water during contact for 60 seconds (the procedure of which is given by the standard ISO 535, TAPPI-T411 measurement).

Thus, the element in sheet form absorbs less than 100g/m²And preferably less than 40g/m²The water of (2).

Preferably, the element in sheet form is of an oil-resistant compound. Thus, a "food" paper may be used, i.e. a complex of paper and a polymeric compound of the polyethylene type or a complex of paper and paraffin, which is able to act as a barrier to water and to oil.

The element in sheet form may optionally be covered with a deposit of adhesive composition. This adhesive layer makes it possible to improve the adhesion of the oxidation dye to the surface of the element in sheet form.

According to a preferred embodiment, said element in sheet form (comprising a surface coated with at least one layer consisting of a dye composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the vat type) can be covered with a protection means for protecting the surface of said element from external elements. Thus, the element in sheet form comprises, on its surface, one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the reduced ketone type (which may be covered by a protective layer). Such a protective layer makes it possible to further minimize the damage of the oxidation dye caused by humidity, light or oxygen in the atmosphere.

Thus, the elements in sheet form can be protected by implementing the methods used in paper painting techniques (clear paints, acrylic varnishes, etc.) and in particular by using water-based or organic acrylic varnish compositions.

In this way, the element in sheet form (comprising a surface coated with at least one layer consisting of a dye composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the vat ketone type) can be protected at the surface with a layer of acrylic varnish.

In other words, the element in sheet form comprises, on its surface, at least one layer consisting of a dye composition comprising one or more oxidation dyes, one or more thiolated reducing agents and one or more organic reducing agents of the vat ketone type, and a layer of acrylic varnish, the two layers being placed one on top of the other.

The mass per unit area of the acrylic varnish layer ranges from 1g/m²To 10g/m²And more particularly from 2g/m²To 5g/m²。

According to a variant, the element in sheet form is covered with a removable protective sheet. For this purpose, the edges of the element in sheet form and the edges of the protective sheet are bonded together by fastening means (in particular an adhesive), which may be produced via any type of method, in particular by heat sealing. Thus, a good bond between the protective sheet and the element in sheet form is ensured.

Advantageously, the protective sheet is UV-opaque to ensure better protection.

According to another variant, the element in sheet form may be covered by another protective means (i.e. a sealed package) defining an oxygen-free space above the element (under vacuum or under an inert atmosphere).

As indicated previously, the substrate comprises a surface coated with at least one layer consisting of a dye composition also comprising one or more oxidation dyes.

These oxidation dyes may be chosen from one or more oxidation bases, optionally in combination with one or more couplers. Preferably, these oxidation dyes comprise at least one oxidation base and at least one coupler.

By way of example, these oxidation bases are chosen from p-phenylenediamine, bisphenylalkylenediamine, p-aminophenol, o-aminophenol and heterocyclic bases and their addition salts.

Among the p-phenylenediamine, examples which may be mentioned include p-phenylenediamine, p-toluenediamine, 2-chloro-p-phenylenediamine, 2, 3-dimethyl-p-phenylenediamine, 2, 6-diethyl-p-phenylenediamine, 2, 5-dimethyl-p-phenylenediamine, N-diethyl-p-phenylenediamine, N-dipropyl-p-phenylenediamine, 4-amino-N, N-diethyl-3-methylaniline, N-bis (. beta. -hydroxyethyl) -p-phenylenediamine, 4-N, n-bis (beta-hydroxyethyl) amino-2-methylaniline, 4-N, N-bis (beta-hydroxyethyl) amino-2-chloroaniline, 2-beta-hydroxyethyl-p-phenylenediamine, 2-fluoro-p-phenylenediamine, 2-isopropyl-p-phenylenediamine, N- (beta-hydroxypropyl) -p-phenylenediamine, 2-hydroxymethyl-p-phenylenediamine, N-dimethyl-3-methyl-p-phenylenediamine, N- (ethyl-beta-hydroxyethyl) -p-phenylenediamine, N- (beta, gamma-dihydroxypropyl) -p-phenylenediamine, N- (4' -aminophenyl) -p-phenylenediamine, N- (beta, gamma-dihydroxypropyl) -p-phenylenediamine, N- (beta-hydroxyethyl) -p-phenylenediamine, N-bis (beta-hydroxyethyl) amino-2-chloroaniline, 2-beta-hydroxyethyl-p-phenylenediamine, 2-isopropyl-p-phenylenediamine, N- (beta-hydroxypropyl) -p-phenylenediamine, N, N-phenyl-p-phenylenediamine, 2-beta-hydroxyethyloxy-p-phenylenediamine, 2-beta-acetylaminoethyloxy-p-phenylenediamine, N- (beta-methoxyethyl) -p-phenylenediamine, 4-aminophenylpyrrolidine, 2-thienyl-p-phenylenediamine, 2-beta-hydroxyethylamino-5-aminotoluene, and 3-hydroxy-1- (4' -aminophenyl) pyrrolidine, and addition salts thereof with an acid.

Among the above-mentioned p-phenylenediamines, 2-isopropyl-p-phenylenediamine, 2-beta-hydroxyethyl-p-phenylenediamine, 2-beta-hydroxyethoxy-p-phenylenediamine, 2, 6-dimethyl-p-phenylenediamine, 2, 6-diethyl-p-phenylenediamine, 2, 3-dimethyl-p-phenylenediamine, N-bis (beta-hydroxyethyl) -p-phenylenediamine, 2-chloro-p-phenylenediamine and 2-beta-acetylaminoethoxy-p-phenylenediamine, and addition salts thereof with an acid are particularly preferred.

Among the bisphenylalkylenediamines, examples which may be mentioned include N, N ' -bis (. beta. -hydroxyethyl) -N, N ' -bis (4' -aminophenyl) -1, 3-diaminopropanol, N ' -bis (. beta. -hydroxyethyl) -N, N ' -bis (4' -aminophenyl) ethylenediamine, N ' -bis (4-aminophenyl) tetramethylenediamine, N ' -bis (. beta. -hydroxyethyl) -N, N ' -bis (4-aminophenyl) tetramethylenediamine, N ' -bis (4-methylaminophenyl) tetramethylenediamine, N ' -bis (ethyl) -N, N ' -bis (4' -amino-3 ' -methylphenyl) ethylenediamine, N ' -bis (4-hydroxyethyl) -N, N ' -bis (4' -aminophenyl) ethylenediamine, N, 1, 8-bis (2, 5-diaminophenoxy) -3, 6-dioxaoctane, and addition salts thereof.

Among p-aminophenols, examples which may be mentioned include p-aminophenol, 4-amino-3-methylphenol, 4-amino-3-fluorophenol, 4-amino-3-chlorophenol, 4-amino-3-hydroxymethylphenol, 4-amino-2-methylphenol, 4-amino-2-hydroxymethylphenol, 4-amino-2-methoxymethylphenol, 4-amino-2-aminomethylphenol, 4-amino-2- (. beta. -hydroxyethylaminomethyl) phenol, and 4-amino-2-fluorophenol, and addition salts thereof with an acid.

Among ortho-aminophenols, examples which may be mentioned include 2-aminophenol, 2-amino-5-methylphenol, 2-amino-6-methylphenol, and 5-acetamido-2-aminophenol, and addition salts thereof.

Among the heterocyclic bases, examples which may be mentioned include pyridine derivatives, pyrimidine derivatives and pyrazole derivatives.

Among the pyridine derivatives, mention may be made of the compounds described, for example, in patents GB 1026978 and GB 1153196, such as 2, 5-diaminopyridine, 2- (4-methoxyphenyl) amino-3-aminopyridine and 3, 4-diaminopyridine, and the addition salts thereof.

Other pyridine oxidation bases useful in the present invention are the 3-aminopyrazolo [1,5-a ] pyridine oxidation bases described, for example, in patent application FR 2801308 or the addition salts thereof. Examples which may be mentioned include pyrazolo [1,5-a ] pyridin-3-ylamine, 2- (acetylamino) pyrazolo [1,5-a ] pyridin-3-ylamine, 2- (morpholin-4-yl) pyrazolo [1,5-a ] pyridin-3-ylamine, 3-aminopyrazolo [1,5-a ] pyridine-2-carboxylic acid, 2-methoxypyrazolo [1,5-a ] pyridin-3-ylamine, (3-aminopyrazolo [1,5-a ] pyridin-7-yl) methanol, 2- (3-aminopyrazolo [1,5-a ] pyridin-5-yl) ethanol, 2- (3-aminopyrazolo [1,5-a ] pyridin-7-yl) ethanol, (3-aminopyrazolo [1,5-a ] pyridin-2-yl) methanol, 3, 6-diaminopyrazolo [1,5-a ] pyridine, 3, 4-diaminopyrazolo [1,5-a ] pyridine, pyrazolo [1,5-a ] pyridine-3, 7-diamine, 7- (morpholin-4-yl) pyrazolo [1,5-a ] pyridin-3-ylamine, pyrazolo [1,5-a ] pyridine-3, 5-diamine, 5- (morpholin-4-yl) pyrazolo [1,5-a ] pyridin-3-ylamine, 2- [ (3-aminopyrazolo [1,5-a ] pyridin-5-yl) (2-hydroxyethyl) amino ] ethanol, a salt thereof, a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable salt thereof, 2- [ (3-aminopyrazolo [1,5-a ] pyridin-7-yl) (2-hydroxyethyl) amino ] ethanol, 3-aminopyrazolo [1,5-a ] pyridin-5-ol, 3-aminopyrazolo [1,5-a ] pyridin-4-ol, 3-aminopyrazolo [1,5-a ] pyridin-6-ol, 3-aminopyrazolo [1,5-a ] pyridin-7-ol, and addition salts thereof.

Among the pyrimidine derivatives, mention may be made of the compounds described, for example, in patent DE 2359399, JP 88-169571, JP05-63124 and EP 0770375 or patent application WO 96/15765, such as 2,4,5, 6-tetraaminopyrimidine, 4-hydroxy-2, 5, 6-triaminopyrimidine, 2-hydroxy-4, 5, 6-triaminopyrimidine, 2, 4-dihydroxy-5, 6-diaminopyrimidine, 2,5, 6-triaminopyrimidine and addition salts thereof and tautomeric forms thereof, where tautomeric equilibrium exists.

Among the pyrazole derivatives, mention may be made of the compounds described in patents DE 3843892, DE 4133957 and patent applications WO 94/08969, WO 94/08970, FR-A-2733749 and DE 19543988, such as 4, 5-diamino-1-methylpyrazole, 4, 5-diamino-1- (. betA. -hydroxyethyl) pyrazole, 3, 4-diaminopyrazole, 4, 5-diamino-1- (4' -chlorobenzyl) pyrazole, 4, 5-diamino-1, 3-dimethylpyrazole, 4, 5-diamino-3-methyl-1-phenylpyrazole, 4, 5-diamino-1-methyl-3-phenylpyrazole, 4-amino-1, 3-dimethyl-5-hydrazinopyrazole, hydrazine derivatives, 1-benzyl-4, 5-diamino-3-methylpyrazole, 4, 5-diamino-3-tert-butyl-1-methylpyrazole, 4, 5-diamino-1-tert-butyl-3-methylpyrazole, 4, 5-diamino-1- (. beta. -hydroxyethyl) -3-methylpyrazole, 4, 5-diamino-1-ethyl-3- (4' -methoxyphenyl) pyrazole, 4, 5-diamino-1-ethyl-3-hydroxymethylpyrazole, 4, 5-diamino-3-hydroxymethyl-1-methylpyrazole, 4, 5-diamino-3-hydroxymethyl-1-isopropylpyrazole, 4, 5-diamino-3-methyl-1-isopropylpyrazole, 4-amino-5- (2' -aminoethyl) amino-1, 3-dimethylpyrazole, 3,4, 5-triaminopyrazole, 1-methyl-3, 4, 5-triaminopyrazole, 3, 5-diamino-1-methyl-4-methylaminopyrazole, 3, 5-diamino-4- (. beta. -hydroxyethyl) amino-1-methylpyrazole, and addition salts thereof. 4, 5-diamino-1- (. beta. -methoxyethyl) pyrazole may also be used.

It will be preferred to use 4, 5-diaminopyrazole and even more preferably 4, 5-diamino-1- (. beta. -hydroxyethyl) pyrazole and/or its salts.

Pyrazole derivatives which may also be mentioned include diamino-N, N-dihydropyrazolopyrazolones, and in particular those described in patent application FR- A-2886136, such as the following compounds and their addition salts: 2, 3-diamino-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one, 2-amino-3-ethylamino-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one, 2-amino-3-isopropylamino-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one, 2-amino-3- (pyrrolidin-1-yl) -6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one, 4, 5-diamino-1, 2-dimethyl-1, 2-dihydropyrazol-3-one, 4, 5-diamino-1, 2-diethyl-1, 2-dihydropyrazol-3-one, 4, 5-diamino-1, 2-bis (2-hydroxyethyl) -1, 2-dihydropyrazol-3-one, 2-amino-3- (2-hydroxyethyl) amino-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one, 2-amino-3-dimethylamino-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one, 2, 3-diamino-5, 6,7, 8-tetrahydro-1H, 6H-pyridazino [1,2-a ] pyrazol-1-one, 4-amino-1, 2-diethyl-5- (pyrrolidin-1-yl) -1, 2-dihydropyrazol-3-one, 4-amino-5- (3-dimethylaminopyrrolidin-1-yl) -1, 2-diethyl-1, 2-dihydropyrazol-3-one, 2, 3-diamino-6-hydroxy-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one.

2, 3-diamino-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one and/or salts thereof will preferably be used.

Heterocyclic color formers which will preferably be used include 4, 5-diamino-1- (. beta. -hydroxyethyl) pyrazole and/or 2, 3-diamino-6, 7-dihydro-1H, 5H-pyrazolo [1,2-a ] pyrazol-1-one and/or salts thereof.

Preferably, these oxidation bases are chosen from p-phenylenediamine, 1-methyl-2, 5-diaminobenzene, p-aminophenol, 1-hydroxyethyl-4, 5-diaminopyrazole sulphate and 2, 3-diaminodihydroxypyrazolone dimethyl sulphonate, and addition salts thereof, and mixtures thereof.

The couplers are advantageously chosen from those conventionally used for dyeing keratin fibres.

Among these couplers, mention may be made in particular of meta-phenylenediamine, meta-aminophenol, meta-diphenol, naphthalene-based couplers and heterocyclic couplers, and also of their addition salts.

Examples which may be mentioned include 2-methyl-5-aminophenol, 5-N- (. beta. -hydroxyethyl) amino-2-methylphenol, 3-aminophenol, 1, 3-dihydroxybenzene, 1, 3-dihydroxy-2-methylbenzene, 4-chloro-1, 3-dihydroxybenzene, 2, 4-diamino-1- (. beta. -hydroxyethyloxy) benzene, 2-amino-4- (. beta. -hydroxyethylamino) -1-methoxybenzene, 1, 3-diaminobenzene, 1, 3-bis (2, 4-diaminophenoxy) propane, 3-ureidoaniline, 3-ureido-1-dimethylaminobenzene, sesamol, 1-. beta. -hydroxyethylamino-3, 4-methylenedioxybenzene, alpha-naphthol, 2-methyl-1-naphthol, 6-hydroxyindole, 4-hydroxy-N-methylindole, 2-amino-3-hydroxypyridine, 6-hydroxybenzomoline, 3, 5-diamino-2, 6-dimethoxypyridine, 1-N- (. beta. -hydroxyethyl) amino-3, 4-methylenedioxybenzene, 2, 6-bis (. beta. -hydroxyethylamino) toluene, 6-hydroxyindoline, 2, 6-dihydroxy-4-methylpyridine, 1-H-3-methylpyrazol-5-one, 1-phenyl-3-methylpyrazol-5-one, 2-hydroxy-3-hydroxypyridine, 6-hydroxy-2, 6-dimethoxy-pyridine, 1-N- (beta. -hydroxyethyl) amino-3-methylenedioxy, 2, 6-dimethylpyrazolo [1,5-b ] -1,2, 4-triazole, 2, 6-dimethyl [3,2-c ] -1,2, 4-triazole and 6-methylpyrazolo [1,5-a ] benzimidazole, addition salts thereof with acids, and mixtures thereof.

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

Preferably, the coupler is selected from the group consisting of resorcinol, 2-methylresorcinol, 5-N- (β -hydroxyethyl) amino-2-methylphenol, 2-methyl-5-aminophenol, 1- β -hydroxyethyloxy-2, 4-diaminobenzene dihydrochloride, 3-aminophenol, (5-N-hydroxyethyl) amino-o-cresol, 5-amino-o-cresol, and 1- β -hydroxyethyloxy-2, 4-diaminobenzene dihydrochloride, addition salts thereof, and mixtures thereof.

As indicated previously, the substrate comprises a surface coated with at least one layer consisting of a dye composition also comprising one or more thiolated reducing agents.

The thiolating reducing agent may be selected from organic compounds containing one or more sulfhydryl (-SH) groups and preferably at least one other functional group selected from carboxylic acid, amine, amide, ester and alcohol functional groups and mixtures thereof.

According to a preferred embodiment of the present invention, the thiolated reducing agent used according to the invention is selected from those having the formula i-1, and also organic or inorganic acid or base salts thereof, optical isomers thereof and tautomers thereof, and solvates thereof, such as hydrates; and/or mixtures thereof:

R-SH

i-1

in said formula i-1:

r represents:

-linear or branched (C)₁-C₈) Alkyl, preferably (C)₁-C₆) Alkyl, optionally substituted, preferably by one or more groups selected from carboxyl groups C (O) OH, (di) (C₁-C₄) (alkyl) amino, hydroxy-OH, mercapto-SH; and/or optionally interrupted by one or more heteroatoms or groups selected from: -O-, -S-, -N (R ' "), C (O), or a combination thereof, such as-O-C (O) -, -C (O) -O-, -N (R '") -C (O) -, or-C (O) -N (R ' ") -; wherein R' "represents a hydrogen atom or (C)₁-C₆) Alkyl, preferably (C)₁-C₄) An alkyl group; or

- (hetero) aryl optionally substituted, in particular, by one or more hydroxyl, mercapto or carboxyl groups.

According to a particular embodiment of the invention, the thiolated reducing agent is chosen from those of formula i-1 as defined previously, and also organic or inorganic acid or base salts thereof, optical isomers thereof and tautomers thereofIsomers, and solvates such as hydrates; and/or mixtures thereof, wherein R represents linear or branched (C)₁-C₈) Alkyl, preferably (C)₁-C₆) An alkyl group, a carboxyl group,

-it is substituted with one or more groups selected from: carboxyl C (O) OH, amino, hydroxyl-OH and mercapto-SH; and/or

-it is optionally interrupted by one or more heteroatoms or groups selected from: -O-, -N (R ' "), C (O), or combinations thereof, such as-O-C (O) -, -C (O) -O-, -N (R '") -C (O) -or-C (O) -N (R ' "), wherein R '" represents a hydrogen atom or (C) R ' "), or₁-C₆) Alkyl, preferably (C)₁-C₄) An alkyl group.

More preferably, R represents a linear or branched, non-intercalated (C)₁-C₈) Alkyl group, still more preferably (C)₁-C₆) An alkyl group.

According to another particular embodiment of the invention, the thiolated reducing agent is selected from those of formula i-1 as defined previously, and also organic or inorganic acid or base salts thereof, optical isomers thereof and tautomers thereof, and solvates thereof, such as hydrates; and/or mixtures thereof, wherein R represents:

-phenyl optionally substituted with one or more hydroxyl, thiol or carboxyl groups; or

-a 5-to 10-membered, preferably 9-or 10-membered bicyclic heteroaryl group comprising 1 to 4 heteroatoms selected from O, S or N, preferably N, optionally substituted with one or more hydroxy or mercapto groups.

Preferably, the thiolating reducing agent is selected from thioglycolic acid, thiolactic acid, cysteine, cysteamine, homocysteine, glutathione, thioglycerol, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiodiglycol, 2-mercaptoethanol, dithiothreitol, N-acetylcysteine, esters and amides of thioglycolic acid or thiolactic acid, especially glycerol monothioglycolate; and also organic or inorganic acid or base salts thereof, optical isomers thereof, tautomers thereof, and solvates thereof such as hydrates; and mixtures of these compounds.

Preferably, the thiolating reducing agent is selected from thioglycolic acid, thiolactic acid, cysteamine, and also organic or inorganic acid or base salts thereof, optical isomers and tautomers thereof, and solvates such as hydrates, and mixtures thereof. Still more preferably, the thiolating reducing agent is selected from thioglycolic acid, thiolactic acid, and mixtures thereof.

As indicated before, the thiolating reducing agent may be used, inter alia, in the form of salts, in particular alkali metal salts (such as sodium and potassium salts), alkaline earth metal salts (such as magnesium and calcium salts), ammonium salts, amine salts and aminoalcohol salts. Ammonium thioglycolate may thus be used as a thiol (thio).

As indicated previously, the substrate comprises a surface coated with at least one layer constituted by a dye composition also comprising one or more organic reducing agents of the vat type.

The term "reductone" denotes a compound comprising an enediol structure- (HO) C ═ C (oh) -adjacent to carbonyl-C (o) -as known per se.

The organic reducing agents of the reductone type used according to the invention therefore preferably have the general formula (IX) and also salts thereof; and/or mixtures thereof:

in the formula

R₁And R₂Each independently of the others, represents a group containing at least one carbon and/or oxygen atom, R₁And R₂Possibly forming a ring, preferably 5-or 6-membered, with three carbon atoms of the compound of formula (IX), the further constituent atoms of the ring being constituted by carbon and/or oxygen atoms.

Preferably, R₁And R₂With the three carbon atoms of the compound of the formula (IX) forming a 5-membered ring, the further constituent atoms of which are composed of carbon and/or oxygen atoms.

As indicated previously, the organic reducing agent of the reductone type of formula (IX) can be in the acid form, or in the form of a salt (in particular in the form of an alkali metal (such as sodium andpotassium) or salts of alkaline earth metals, such as calcium and magnesium), or in the form of esters, in particular C₈To C₃₀Ester forms of fatty acids).

Preferably, the organic reducing agent of the reductone type of formula (IX) is a lactone.

According to a preferred embodiment of the invention, the organic reducing agent of the reducing ketone type is selected from reducing acids, ascorbic acid, erythronic acid or isoascorbic acid, and also salts thereof, such as sodium or potassium salts, ascorbyl palmitate and/or mixtures thereof.

More preferably, the organic reducing agent of the reductone type is selected from ascorbic acid, erythronic acid, and salts of these compounds (especially sodium or potassium salts).

According to a particular embodiment of the invention, the weight ratio of the total weight content of thiolated reducing agent and organic reducing agent of the reductone type present in the dye composition to the total weight content of oxidation dye present in the dye composition is from 0.05 to 40, preferably from 0.1 to 30, preferably from 0.2 to 30.

The dye composition may cover all or a portion of the surface of the substrate. Thus, the substrate surface may be completely or partially covered with one or several layers of the dye composition.

Preferably, the dye preparation composition is deposited on a portion of the surface of the substrate and represents a pattern which, upon contact with the keratin fibres and the oxidizing aqueous composition, will make it possible to produce a coloured pattern on said fibres. In other words, the oxidation dye is deposited on the surface of the substrate in a pattern. Thus, the substrate surface comprises one or more layers of the dye composition arranged in one or more specific geometric forms, called patterns, which, after reaction with the oxidizing aqueous composition, result in a colored pattern on the fibers.

The pattern may have any form, in particular a geometric form.

Thus, the dye composition comprising the oxidation dye, the thiolated reducing agent, and the organic reducing agent of the reduced ketone type is present on a portion of the surface of the substrate, and exhibits a pattern having a desired form.

The substrate may comprise a copy of the desired pattern on the side opposite to the side carrying the oxidation dye, the thiolated reducing agent, and the organic reducing agent of the reduced ketone type. The creation of these patterns on the opposite faces makes it possible to indicate the locations where the oxidation dye, the thiolated reducing agent and the organic reducing agent of the reduced ketone type can then be deposited on the surface of the substrate. This creation facilitates the subsequent placement of the substrate on the keratin fibers at the location where it is desired to create such a pattern.

According to a preferred embodiment of the invention, the surface of the substrate comprises one or more patterns before the deposition of the oxidation dye, the thiolated reducing agent and the organic reducing agent of the reduced ketone type. In other words, the patterns that are desired to be obtained on the keratin fibres can be produced (for example printed) beforehand on the surface of the substrate intended to be pretreated.

According to another preferred embodiment of the invention, the substrate is transparent.

The substrate may optionally include a surface coated with at least one layer comprised of a dye composition further comprising one or more alkaline agents. In other words, the dye composition may optionally comprise one or more oxidation dyes, one or more thiolated reducing agents, one or more organic reducing agents of the reductone type, and one or more alkaline agents.

These alkaline agents may be chosen from carbonates, alkanolamines, such as monoethanolamine, diethanolamine, triethanolamine and derivatives thereof, oxyethylenated and/or oxypropylenated ethylenediamines, inorganic or organic hydroxides, alkali metal silicates, such as sodium metasilicate, amino acids, preferably basic amino acids, such as arginine, lysine, ornithine, citrulline and histidine, and compounds having the following formula (I):

wherein:

w is optionally substituted by, inter alia, hydroxy or C₁-C₄Alkyl substituted divalent (C)₁-C₈) Alkylene, preferably propylene;

-R_a、R_b、R_cand R_dMay be the same or different and represents a hydrogen atom or C₁-C₄Alkyl or C₁-C₄A hydroxyalkyl group.

These inorganic or organic hydroxides are preferably selected from i) hydroxides of alkali metals, ii) hydroxides of alkaline earth metals, such as sodium hydroxide or potassium hydroxide, III) hydroxides of transition metals, such as hydroxides of metals from groups III, IV, V and VI, IV) hydroxides of lanthanides or actinides, quaternary ammonium hydroxides and guanidinium hydroxides.

The hydroxide may be formed in situ, for example, guanidine hydroxide, by reacting calcium hydroxide with guanidine carbonate.

In particular, the alkaline agent used is a solid in the dry state.

In a first variant of the invention, the alkaline agent is solid prior to use in the dye formulation composition for treating the surface of a substrate and is preferably selected from a carbonate, an inorganic hydroxide (such as soluble sodium or potassium hydroxide) or a silicate.

In another variant of the invention, these alkaline agents are chosen from alkanolamines, in particular monoethanolamine, diethanolamine and triethanolamine.

The substrate may optionally comprise a surface coated with at least one layer consisting of a dye composition further comprising one or more additional antioxidant actives, preferably solid, selected from sulfites, bisulfites such as ammonium bisulfite and alkali or alkaline earth bisulfites such as for example sodium bisulfite, sulfinates, before use in the dye formulation composition.

The dye composition may optionally also comprise one or more compounds capable of slowing the oxidative condensation reaction selected from-gluconolactone, sodium gluconate, potassium gluconate, calcium gluconate, potassium bitartrate, sodium acetate, sorbitol, acids such as ethylenediaminetetraacetic acid (EDTA), citric acid, phosphoric acid and tartaric acid.

The dye composition may also optionally comprise one or more organic solvents.

Organic solvents which may be mentioned include linear or branched and preferably saturated monohydric or dihydric alcohols containing from 2 to 6 carbon atoms, such as ethanol, isopropanol, hexanediol (2-methyl-2, 4-pentanediol), neopentyl glycol and 3-methyl-1, 5-pentanediol, butanediol, dipropylene glycol and propylene glycol; aromatic alcohols such as benzyl alcohol or phenethyl alcohol; polyols containing more than 2 hydroxyl functional groups, such as glycerol; polyol ethers, such as ethylene glycol or propylene glycol monomethyl ether, monoethyl ether, monobutyl ether; and also diethylene glycol alkyl ethers, especially C₁-C₄Alkyl ethers, such as diethylene glycol monoethyl ether or monobutyl ether.

The substrate may optionally include a surface coated with at least one layer comprised of a dye composition further comprising one or more activators or catalysts. In particular, the substrate further comprises a layer of one or more metal salts in an amount ranging from 1% to 20% by weight relative to the weight of the oxidation dye present in the dye formulation composition prior to deposition on the substrate surface.

As indicated previously, the oxidation dyeing process uses an oxidizing aqueous composition containing one or more chemical oxidizing agents.

The term "chemical oxidant" means an oxidant other than atmospheric oxygen.

Preferably, the chemical oxidizing agent is selected from hydrogen peroxide, urea peroxide, alkali metal bromates or ferricyanides, peroxygenated salts, such as alkali metal or alkaline earth metal persulfates, perborates and percarbonates, and also peracids and precursors thereof.

Even more preferably, the chemical oxidizing agent is selected from hydrogen peroxide, peroxygenated salts, carbamide peroxide or alkali metal bromates or ferricyanides.

This oxidizing agent advantageously consists of hydrogen peroxide, in particular in the form of an aqueous solution (aqueous hydrogen peroxide), the concentration of which may range more particularly from 0.1% to 50% by weight, even more preferably from 0.5% to 20% by weight and better still from 1% to 15% by weight with respect to the oxidizing composition.

Preferably, the chemical oxidizing agent is selected from hydrogen peroxide and/or peroxygenated salts.

Preferably, the oxidizing aqueous composition further comprises one or more alkaline agents, in particular as described previously.

The use of an oxidizing aqueous composition comprising one or more alkaline agents during the dyeing process according to the invention makes it possible to cause, in particular, a lightening effect on the treated keratin fibres, which enhances the visibility of the pattern obtained with the oxidizing dyes present on the surface of the substrate.

This use is particularly advantageous for dyeing black or chestnut-brown hair.

The oxidizing aqueous composition may also comprise one or more thickeners or viscosity modifiers, such as hydroxyalkyl celluloses, for example hydroxyethyl cellulose, in particularSold under the index Natrosol Plus 330.

The oxidizing aqueous composition may also comprise one or more colorants such as couplers.

In this way, placed in contact with these keratin fibres, the pretreated substrate and the oxidizing aqueous composition containing one or more couplers will make it possible to produce different colourations, given that the couplers present in the oxidizing composition will be able to react with the oxidation bases present on the substrate.

The use of an oxidizing aqueous composition containing one or more couplers is advantageous because it makes it possible to limit the number of substrates used by varying the nature of the oxidizing composition and at the same time increase the possible results as regards the colour.

The use of an oxidizing aqueous composition containing one or more couplers thus makes it possible to obtain a wide range of colours.

According to a preferred embodiment of the present invention, the oxidizing aqueous composition further comprises one or more alkaline agents and/or one or more colorants, such as couplers.

According to another preferred embodiment of the invention, the oxidation dyeing process comprises a step of applying to the keratin fibres a substrate as described previously, followed by a step of applying to the keratin fibres an oxidizing aqueous composition comprising one or more chemical oxidizing agents.

Specifically, keratin fibers are placed on the surface of a substrate carrying the oxidation dye, i.e. where the surface of the substrate is covered with at least one layer consisting of a dye composition comprising the oxidation dye, the thiolated reducing agent and the organic reducing agent of the reduced ketone type; and then applying the oxidizing aqueous composition to the fibers. The oxidation dyes are thereby dissolved, react with the oxidizing agent and dye the keratin fibres.

The oxidizing aqueous composition is applied, in particular, using an applicator, in particular with a brush or by hand.

According to this embodiment, after application of the oxidizing composition, the hair strands thus treated may be protected with paper in order to protect other hair strands that have not been treated.

According to another embodiment, the oxidation dyeing process comprises a step of applying to the keratin fibres an oxidizing aqueous composition comprising one or more chemical oxidizing agents, as previously described, followed by a step of applying to the keratin fibres a substrate as previously defined.

In this example, the order of application between the substrate and the oxidizing aqueous composition is therefore inverted with respect to the previous example.

In this example, keratin fibers are placed, inter alia, on the upper surface of a support, such as a sheet of paper, an oxidizing aqueous composition is applied to the fibers and then a substrate as previously described is applied to the fibers. The oxidation dyes present on the surface of the substrate are thereby dissolved, react with the oxidizing agent and dye the coated keratin fibers.

According to this example, a substrate as described previously is applied to keratin fibres treated with an oxidizing aqueous composition, so that the surface containing the oxidation dye comes into contact with these fibres.

This dyeing process, hereinafter referred to as "counter-dyeing process", has the advantage of minimizing or even eliminating the problem of contamination arising between the applicator for applying the oxidizing composition and the oxidizing dye originating from the substrate.

Specifically, when the keratin fibres are first placed on a substrate as described previously, the applicator for applying the oxidizing composition is then brought into contact with the oxidation dyes originating from said substrate, which react with these chemical oxidizing agents. Once application has been carried out, the applicator thus contains both the oxidation dye and the oxidizing aqueous composition, with the following consequences: causing the risk of contamination of the remaining oxidizing aqueous composition and increasing the risk of damaging the coloration of other keratin fibres.

In particular, when the applicator is a brush, the bristles thereof contain an oxidation dye which has reacted with the oxidizing agent of the oxidizing composition. Thus, the brush may damage the remaining oxidizing composition, given that its bristles contain oxidizing dyes.

The counter-dyeing process thus makes it possible to avoid this contamination problem, since the applicator is not in contact with the oxidation dye originating from the substrate. Thereby, the remaining oxidizing aqueous composition is not contaminated by the applicator and the risk of damaging coloration is minimized.

The counterdyeing process is therefore particularly advantageous.

Preferably, the oxidizing aqueous composition used in the counterdyeing process also contains one or more alkaline agents.

The substrate comprising a surface coated with at least one layer constituted by a dye composition may be applied on the keratin fibres for a period of time ranging from 5 minutes to 60 minutes, and preferably ranging from 10 minutes to 30 minutes.

The oxidizing aqueous composition may be applied on the keratin fibres for a period of time ranging from 5 minutes to 60 minutes, and preferably ranging from 10 minutes to 30 minutes.

The substrate and oxidizing aqueous composition as previously described may be applied at room temperature (25 ℃), optionally with the temperature being raised, which may be up to 60 ℃.

After treatment, the human keratin fibres are optionally rinsed with water, optionally washed with a shampoo and then rinsed with water, and then dried or left to dry.

Preferably, the substrate comprises a surface coated with at least one layer consisting of a dye composition comprising one or more oxidation dyes, one or more thiolated reducing agents, one or more organic reducing agents of the vat type, and one or more alkaline agents, and the oxidizing aqueous composition contains one or more chemical oxidizing agents and optionally one or more alkaline agents.

Method for producing a substrate

The present invention also relates to a process for producing a substrate as defined previously, comprising at least one step of depositing on the surface of the substrate at least one dye formulation composition containing one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the vat ketone type; and at least one step of drying the substrate.

It is understood that for the purposes of the present invention, the dye formulation composition used in the process for producing a substrate comprises one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the vat ketone type, as previously described for the dye composition.

It is also to be understood that for the purposes of the present invention, the dye formulation composition may optionally comprise one or more alkaline agents as previously described for the compounds optionally present in the dye composition, one or more additional antioxidant actives, one or more compounds capable of slowing the oxidative condensation reaction, and/or one or more organic solvents.

The dye formulation composition intended to be deposited on the surface of the substrate may be liquid or in powdered form at room temperature, preferably liquid at room temperature.

Preferably, the substrate is pretreated with at least one dye formulation composition comprising one or more oxidation dyes, one or more thiolated reducing agents, one or more organic reducing agents of the reductone type, and one or more basic agents.

The oxidation bases and optionally couplers as described previously can advantageously represent from 0.01% to 99% by weight, preferably from 1% to 50% by weight and better still from 5% to 40% by weight relative to the total weight of the dye preparation composition before deposition on the surface of the substrate.

The mercaptanizing reducing agent as described previously is preferably present in a total amount ranging from 0.5% to 60% by weight, preferably from 1% to 50% by weight, more particularly from 4% to 45% by weight and better still from 10% to 40% by weight, relative to the total weight of the dye formulation composition before deposition on the surface of the substrate.

The organic reducing agent of the reductone type as described previously is preferably present in a total amount ranging from 0.5% to 50% by weight, preferably from 1% to 45% by weight, more particularly from 4% to 35% by weight and better still from 8% to 30% by weight, relative to the total weight of the dye formulation composition before deposition on the surface of the substrate.

The alkaline agent may preferably be present in a content ranging from 0.01% to 20% by weight relative to the total weight of the dye formulation composition prior to deposition on the surface of the substrate.

The additional antioxidant active may preferably be present in a content ranging from 0.05% to 1% by weight relative to the total weight of the dye formulation composition prior to deposition on the surface of the substrate.

The compound capable of slowing the oxidative condensation reaction may preferably be present in a content of less than or equal to 2% by weight, preferably less than or equal to 1% by weight, even better still ranging from 0.05% to 0.2% by weight, relative to the total weight of the dye formulation composition before deposition on the surface of the substrate.

The dye formulation composition comprising one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the reductone type may be aqueous or anhydrous, preferably aqueous.

When the dye formulation composition is aqueous and contains one or more alkaline agents, the pH of the dye formulation composition preferably ranges from 7.5 to 13, better still from 8 to 12 and even better still from 8 to 11.

Said dye composition present on the surface of the substrate may optionally result from a continuous treatment of the substrate with one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the reductone type on the one hand, optionally one or more alkaline agents, and optionally one or more active agents as previously described on the other hand.

Preferably, the process for producing a substrate as previously described comprises at least one step of depositing on the surface of the substrate at least one dye formulation composition containing one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the vat ketone type; and at least one step of drying said substrate; more preferably, the step of depositing on the surface of the substrate comprises depositing the dye formulation composition by a printing process.

In other words, the dye composition is printed on the surface of the substrate, that is to say using a printing process that enables to obtain a substrate as defined previously.

According to this preference, the printing method for depositing the dye composition onto the surface of the substrate may be a screen printing method, a flexographic printing method, an offset printing method, an inkjet printing method or a laser printing method.

Preferably, at least one dye formulation composition as defined previously is applied to the substrate by screen printing or by means of an ink jet printer.

More preferably, the dye formulation composition as defined previously is printed onto the surface of the substrate by means of an ink jet printer.

When the production process comprises the use of a printing process using a laser printer, then the dye formulation composition containing the oxidation dye, the thiolated reducing agent, and the organic reducing agent of the reduced ketone type is in powder form.

Preferably, the process for producing a substrate corresponds to a process for printing a substrate, wherein at least one layer of the dye formulation composition as defined previously is applied to the substrate by screen printing, flexo printing, offset printing or inkjet printing.

Advantageously, in this embodiment by printing, the substrate is an element in the form of a sheet.

This preferred production method, corresponding to the method for printing a substrate, can be carried out in the hairstyling salon itself, in particular by means of an inkjet printer or laser printer, before the oxidative dyeing method according to the invention is carried out.

Alternatively, this preferred method can also be performed outside of the hair styling salon and as such the user only has to use the substrate to color the hair.

In this case, the pre-treated substrate may be supplied to the user to create a uniform coloration and/or pattern on the hair.

According to a preferred embodiment of the present invention, the method for producing a substrate comprises at least one deposition step comprising depositing at least one dye formulation composition onto the surface of the substrate covered with a layer of adhesive composition. This adhesive layer may cover all or a portion of the substrate. In particular, the adhesive layer may represent a pattern.

According to another preferred embodiment of the invention, the method for producing a substrate as described previously comprises at least one deposition step comprising the partial deposition, via a printing process, of at least one dye formulation composition containing one or more oxidation dyes, one or more mercaptanization reducing agents and one or more organic reducing agents of the vat ketone type onto the surface of a substrate.

According to this further preferred embodiment, the oxidation dye, the thiolated reducing agent, and the organic reducing agent of the reduced ketone type are deposited onto the surface of the substrate in the form of one or more patterns. In particular, the patterns may be square, circular, oval, elliptical or triangular, in the form of filling patterns or in the form of lines surrounding these patterns. They may also be thick or thin, straight or curved, cross-hatched, representative letters, stylized drawings or geometric patterns. They may also be dashed lines or dots.

According to one embodiment of the invention, the method for producing a substrate comprises at least one step of depositing on the surface of the substrate at least one dye formulation composition containing said oxidation dye, said thiolated reducing agent, and said organic reducing agent of the reduced ketone type, followed by a step of heating said surface. Preferably, the surface portion of the substrate is heated to produce one or more patterns on the surface.

According to another embodiment of the invention, the method for producing a substrate comprises at least one step of depositing on the surface of the substrate at least one dye preparation composition containing said oxidation dye, said thiolated reducing agent, and said organic reducing agent of the reduced ketone type, followed by a step of removing or inactivating all or part of the oxidation dye in some areas. In this way, such a method may result in the creation of one or more patterns on the surface of the substrate.

The step of removing all or part of the oxidation dye in some areas may be performed by means of scraping, wiping with a sponge, blowing, sucking or using an adhesive surface or a surface that is wetted at the location where removal of the oxidation dye is desired.

The step of inactivating all or part of the oxidation dye in some areas on the surface of the substrate may be carried out by means of chemical conversion (e.g. oxidation or reduction), or by covering with a protective compound.

Furthermore, the method for producing a substrate may further comprise a step comprising applying a starch film in order to enhance the robustness of the substrate and to improve the deposition of oxidation dyes on the surface of the substrate.

The starch film may be thin, about 2g/m²Or thick, about 70g/m²。

Once the dye formulation composition has been deposited on the surface of the substrate, the substrate is dried.

The substrate thus pretreated according to the production method is preferably dried over a period of time ranging from 5 minutes to 120 minutes, preferably from 5 minutes to 90 minutes, more preferably from 1 minute to 60 minutes and better still from 5 minutes to 60 minutes.

Preferably, the step of drying the substrate comprises drying the substrate in open air.

Once the substrate has been prepared, it comprises a surface coated with at least one layer consisting of a dye composition comprising one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the vat type.

For the purposes of the present invention, the dye composition has a total water content of less than 20% by weight, preferably less than or equal to 15% by weight, more preferably less than or equal to 10% by weight, relative to the total weight of the dye composition.

The oxidation bases and optionally couplers as previously described can advantageously represent from 0.01% to 99% by weight, preferably from 1% to 50% by weight and better still from 5% to 40% by weight relative to the total weight of the dye composition.

Preferably, the dye composition comprises one or more oxidation dyes as previously described in a content ranging from 0.01% to 99% by weight, preferably from 1% to 50% by weight and better still from 5% to 40% by weight, relative to the total weight of the dye composition.

The mercaptanizing reducing agent as described previously is preferably present in a total amount ranging from 0.5% to 60% by weight, preferably from 1% to 50% by weight, more particularly from 4% to 45% by weight and better still from 10% to 40% by weight, relative to the total weight of the dye composition.

The organic reducing agents of the reductone type as described previously are preferably present in a total amount ranging from 0.5% to 50% by weight, preferably from 1% to 45% by weight, more particularly from 4% to 35% by weight and better still from 8% to 30% by weight, relative to the total weight of the dye composition.

The alkaline agent as previously described may preferably be present in a content ranging from 0.01% to 20% by weight relative to the total weight of the dye composition.

The additional antioxidant active may preferably be present in a content ranging from 0.5% to 10% by weight relative to the total weight of the dye composition.

The compound capable of slowing down the oxidative condensation reaction as described previously may preferably be present in a content of less than or equal to 10% by weight, preferably less than or equal to 5% by weight, even better still ranging from 0.5% to 2% by weight, relative to the total weight of the dye composition.

The invention also relates to an element in sheet form as described previously, said element being pretreated on its surface by a dye preparation composition comprising one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the reducing ketone type, as described previously.

The element in sheet form is therefore covered on its surface, in whole or in part, with one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the reduced ketone type.

The element in sheet form comprises at its surface one or more oxidation dyes, one or more thiolated reducing agents, and one or more organic reducing agents of the reduced ketone type.

In particular, the oxidation dye, the thiolated reducing agent and the organic reducing agent of the reduced ketone type have been printed on the element in sheet form.

The element in sheet form may be made of a nonwoven fibrous material, in particular a nonwoven made of cellulose or derivatives thereof. In particular, the element in sheet form may be a paper of the kraft type, which has the advantage of good printing and of producing precise patterns. Specifically, the coloured pattern obtained on the keratin fibres does not flow after application of the oxidizing aqueous composition.

The element in sheet form may be a sheet of plastic material which has, inter alia, the advantage of imparting a very good colouring power, which makes it possible to produce patterns whose colouring is intense. Furthermore, the sheet of plastic material does not absorb the water present in the oxidizing aqueous composition, which makes it possible to avoid the creation of dry zones under the keratin fibres during the application of the composition.

According to a first advantageous embodiment, said element in sheet form is a plastic sheet covered with a thin layer of paper, in particular having a thickness of less than 50 μm and more preferably less than 30 μm, such as a cigarette paper or a paper layer which can be decomposed in the presence of water (such as toilet paper), or a thin layer of hydrophilic material (preferably dissolved, such as cellulose or hydrophilic silica), preferably having a thickness in the range of 5 to 200 μm.

According to this embodiment, the tissue layer allows a fast drying and prevents the coloring from flowing after the application of the oxidizing aqueous composition. Furthermore, the paper layer located below the tissue paper, due to its low thickness, absorbs little or no oxidation dyes originating from the element in sheet form. As a result, the keratin fibers are well imparted with a coloration by the tissue layer, which results in a clear coloration pattern, among other things. Furthermore, said element in sheet form according to this embodiment makes it possible to minimize the dry area under the keratin fibres.

When using a support formed by a paper layer, which is preferably slightly absorbent or non-absorbent, covered with a paper layer capable of degrading on contact with water:

the degradable paper layer (possibly ranging in thickness from 10 to 200 μm) allows for rapid drying and prevents the coloring from flowing after application of the oxidizing aqueous composition. Furthermore, the paper layer located below the degradable paper, due to its low thickness, absorbs little or no oxidation dyes originating from the element in sheet form. As a result, the keratin fibers are well imparted with a coloration by the tissue layer, which results in a clear coloration pattern, among other things. Furthermore, said element in sheet form according to this embodiment makes it possible to minimize the dry area under the keratin fibres.

In the case of using a support formed by a layer of hydrophilic material:

the layer of hydrophilic material is typically 5 to 200 μm thick, which allows for rapid drying and prevents the coloring from flowing after application of the oxidizing aqueous composition. This results in particular in a clear coloured pattern.

According to a second advantageous embodiment, the element in sheet form is a micro-honeycomb (i.e. a sheet perforated with holes, the holes being spaced apart from each other by a plastic material. Thus, the oxidizing aqueous composition becomes housed in the pores of the substrate, which will enable better imparting of the dyeing capacity on the keratin fibres after application of the oxidizing aqueous composition.

The holes are located on the surface of the element in sheet form, within a thickness in the range of 10% to 90% of the thickness of the sheet.

According to this embodiment, the element in sheet form also has the following advantages: good printing, better imparting of coloration, especially producing strongly colored patterns, no excessive absorption of water originating from the oxidizing aqueous composition and minimized risk of colored flow, which produces precisely colored patterns on keratin fibers.

The following examples are intended to illustrate the invention, but are not limiting in nature.